Vacuum Radiance-Temperature Standard Facility for Infrared Remote Sensing at NIM

NASA Astrophysics Data System (ADS)

Hao, X. P.; Song, J.; Xu, M.; Sun, J. P.; Gong, L. Y.; Yuan, Z. D.; Lu, X. F.

2018-06-01

As infrared remote sensors are very important parts of Earth observation satellites, they must be calibrated based on the radiance temperature of a blackbody in a vacuum chamber prior to launch. The uncertainty of such temperature is thus an essential component of the sensors' uncertainty. This paper describes the vacuum radiance-temperature standard facility (VRTSF) at the National Institute of Metrology of China, which will serve to calibrate infrared remote sensors on Chinese meteorological satellites. The VRTSF can be used to calibrate vacuum blackbody radiance temperature, including those used to calibrate infrared remote sensors. The components of the VRTSF are described in this paper, including the VMTBB, the LNBB, the FTIR spectrometer, the reduced-background optical system, the vacuum chamber used to calibrate customers' blackbody, the vacuum-pumping system and the liquid-nitrogen-support system. The experimental methods and results are expounded. The uncertainty of the radiance temperature of VMTBB is 0.026 °C at 30 °C over 10 μm.

High pressure and temperature optical flow cell for near-infra-red spectroscopic analysis of gas mixtures.

PubMed

Norton, C G; Suedmeyer, J; Oderkerk, B; Fieback, T M

2014-05-01

A new optical flow cell with a new optical arrangement adapted for high pressures and temperatures using glass fibres to connect light source, cell, and spectrometer has been developed, as part of a larger project comprising new methods for in situ analysis of bio and hydrogen gas mixtures in high pressure and temperature applications. The analysis is based on measurements of optical, thermo-physical, and electromagnetic properties in gas mixtures with newly developed high pressure property sensors, which are mounted in a new apparatus which can generate gas mixtures with up to six components with an uncertainty of composition of as little as 0.1 mol. %. Measurements of several pure components of natural gases and biogases to a pressure of 20 MPa were performed on two isotherms, and with binary mixtures of the same pure gases at pressures to 17.5 MPa. Thereby a new method of analyzing the obtained spectra based on the partial density of methane was investigated.

a Brief Climatology of Cirrus LIDAR Ratios Measured by High Spectral Resolution LIDAR

NASA Astrophysics Data System (ADS)

Kuehn, R.; Holz, R.; Hair, J. W.; Vaughan, M. A.; Eloranta, E. W.

2015-12-01

Our ability to detect and probe the vertical extent of cirrus was hugely improved with the launch of the NASA-CNES CALIPSO mission in April 2006. However, our skill at retrieving the optical properties of the cirrus detected by the CALIPSO lidar is not yet commensurate with our detection abilities. As with any new observing system, CALIPSO faces challenges and uncertainties in the retrieval of the geophysical parameters from its fundamental measurements. Specifically, extinction and optical depth retrievals for elastic backscatter lidars like CALIPSO typically rely on a priori assumptions about layer-mean extinction-to-backscatter ratios (AKA lidar ratios), which can vary regionally and for which uncertainties are high. To improve CALIPSO optical properties retrievals, we show High Spectral Resolution Lidar (HSRL) measurements acquired with systems from the University of Wisconsin and NASA Langley. HSRLs can directly determine ice cloud extinction and lidar ratio by separately measuring the molecular and particulate components of the total backscattered signal, thus largely eliminating many of the uncertainties inherent in elastic backscatter retrievals. These measurements were acquired during the SEAC4RS (Huntsville, AL, USA and Singapore), and FRAPPE/DISCOVER-AQ 2014 (BAO tower near Boulder, CO, USA) field campaigns, and an intensive operations period in Hampton, VA, USA.

Hierarchical multi-scale approach to validation and uncertainty quantification of hyper-spectral image modeling

NASA Astrophysics Data System (ADS)

Engel, Dave W.; Reichardt, Thomas A.; Kulp, Thomas J.; Graff, David L.; Thompson, Sandra E.

2016-05-01

Validating predictive models and quantifying uncertainties inherent in the modeling process is a critical component of the HARD Solids Venture program [1]. Our current research focuses on validating physics-based models predicting the optical properties of solid materials for arbitrary surface morphologies and characterizing the uncertainties in these models. We employ a systematic and hierarchical approach by designing physical experiments and comparing the experimental results with the outputs of computational predictive models. We illustrate this approach through an example comparing a micro-scale forward model to an idealized solid-material system and then propagating the results through a system model to the sensor level. Our efforts should enhance detection reliability of the hyper-spectral imaging technique and the confidence in model utilization and model outputs by users and stakeholders.

Defining the measurand in radius of curvature measurements

NASA Astrophysics Data System (ADS)

Davies, Angela; Schmitz, Tony L.

2003-11-01

Traceable radius of curvature measurements are critical for precision optics manufacture. An optical bench measurement of radius is very repeatable and is the preferred method for low-uncertainty applications. On an optical bench, the displacement of the optic is measured as it is moved between the cat's eye and confocal positions, each identified using a figure measuring interferometer. Traceability requires connection to a basic unit (the meter, here) in addition to a defensible uncertainty analysis, and the identification and proper propagation of all uncertainty sources in this measurement is challenging. Recent work has focused on identifying all uncertainty contributions; measurement biases have been approximately taken into account and uncertainties combined in an RSS sense for a final measurement estimate and uncertainty. In this paper we report on a new mathematical definition of the radius measurand, which is a single function that depends on all uncertainty sources, such as error motions, alignment uncertainty, displacement gauge uncertainty, etc. The method is based on a homogeneous transformation matrix (HTM) formalism, and intrinsically defines an unbiased estimate for radius, providing a single mathematical expression for uncertainty propagation through a Taylor-series expansion.

Uncertainty in cloud optical depth estimates made from satellite radiance measurements

NASA Technical Reports Server (NTRS)

Pincus, Robert; Szczodrak, Malgorzata; Gu, Jiujing; Austin, Philip

1995-01-01

The uncertainty in optical depths retrieved from satellite measurements of visible wavelength radiance at the top of the atmosphere is quantified. Techniques are briefly reviewed for the estimation of optical depth from measurements of radiance, and it is noted that these estimates are always more uncertain at greater optical depths and larger solar zenith angles. The lack of radiometric calibration for visible wavelength imagers on operational satellites dominates the uncertainty retrievals of optical depth. This is true for both single-pixel retrievals and for statistics calculated from a population of individual retrievals. For individual estimates or small samples, sensor discretization can also be significant, but the sensitivity of the retrieval to the specification of the model atmosphere is less important. The relative uncertainty in calibration affects the accuracy with which optical depth distributions measured by different sensors may be quantitatively compared, while the absolute calibration uncertainty, acting through the nonlinear mapping of radiance to optical depth, limits the degree to which distributions measured by the same sensor may be distinguished.

Optical calibration of the Auger fluorescence telescopes

NASA Astrophysics Data System (ADS)

Matthews, John A. J.

2003-02-01

The Pierre Auger Observatory is optimized to study the cosmic ray spectrum in the region of the Greisen-Zatsepin-Kuz'min (GZK) cutoff, i.e.cosmic rays with energies of ~1020eV. Cosmic rays are detected as extensive air showers. To measure these showers each Auger site combines a 3000sq-km ground array with air fluorescence telescopes into a hybrid detector. Our design choice is motivated by the heightened importance of the energy scale, and related systematic uncertainties in shower energies, for experiments investigating the GZK cutoff. This paper focuses on the optical calibration of the Auger fluorescence telescopes. The optical calibration is done three independent ways: an absolute end-to-end calibration using a uniform, calibrated intensity, light-source at the telescope entrance aperture, a component by component calibration using both laboratory and in-situ measurements, and Rayleigh scattered light from external laser beams. The calibration concepts and related instrumentation are summarized. Results from the 5-month engineering array test are presented.

Hierarchical Multi-Scale Approach To Validation and Uncertainty Quantification of Hyper-Spectral Image Modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Engel, David W.; Reichardt, Thomas A.; Kulp, Thomas J.

Validating predictive models and quantifying uncertainties inherent in the modeling process is a critical component of the HARD Solids Venture program [1]. Our current research focuses on validating physics-based models predicting the optical properties of solid materials for arbitrary surface morphologies and characterizing the uncertainties in these models. We employ a systematic and hierarchical approach by designing physical experiments and comparing the experimental results with the outputs of computational predictive models. We illustrate this approach through an example comparing a micro-scale forward model to an idealized solid-material system and then propagating the results through a system model to the sensormore » level. Our efforts should enhance detection reliability of the hyper-spectral imaging technique and the confidence in model utilization and model outputs by users and stakeholders.« less

Cheap and fast measuring roughness on big surfaces with an imprint method

NASA Astrophysics Data System (ADS)

Schopf, C.; Liebl, J.; Rascher, R.

2017-10-01

Roughness, shape and structure of a surface offer information on the state, shape and surface characteristics of a component. Particularly the roughness of the surface dictates the subsequent polishing of the optical surface. The roughness is usually measured by a white light interferometer, which is limited by the size of the components. Using a moulding method of surfaces that are difficult to reach, an imprint is taken and analysed regarding to roughness and structure. This moulding compound method is successfully used in dental technology. In optical production, the moulding compound method is advantageous in roughness determination in inaccessible spots or on large components (astrological optics). The "replica method" has been around in metal analysis and processing. Film is used in order to take an impression of a surface. Then, it is analysed for structures. In optical production, compound moulding seems advantageous in roughness determination in inaccessible spots or on large components (astrological optics). In preliminary trials, different glass samples with different roughness levels were manufactured. Imprints were taken from these samples (based on DIN 54150 "Abdruckverfahren für die Oberflächenprüfung"). The objective of these feasibility tests was to determine the limits of this method (smallest roughness determinable / highest roughness). The roughness of the imprint was compared with the roughness of the glass samples. By comparing the results, the uncertainty of the measuring method was determined. The spectrum for the trials ranged from rough grind (0.8 μm rms), over finishing grind (0.6 μm rms) to polishing (0.1 μm rms).

Partial polarization: a comprehensive student exercise

NASA Astrophysics Data System (ADS)

Topasna, Gregory A.; Topasna, Daniela M.

2015-10-01

We present a comprehensive student exercise in partial polarization. Students are first introduced to the concept of partial polarization using Fresnel Equations. Next, MATHCAD is used to compute and graph the reflectance for dielectrics materials. The students then design and construct a simple, easy to use collimated light source for their experiment, which is performed on an optical breadboard using optical components typically found in an optics lab above the introductory level. The students obtain reflection data that is compared with their model by a nonlinear least square fit using EXCEL. Sources of error and uncertainty are discussed and students present a final written report. In this one exercise students learn how an experiment is constructed "from the ground up". They gain practical experience on data modeling and analysis, working with optical equipment, machining and construction, and preparing a final presentation.

Estimate of the Aerosol Anthropogenic Component and Focusing from Satellite Data

NASA Technical Reports Server (NTRS)

Kaufman, Yoram; Remer, Lorraine A.; Chin, Mian

2004-01-01

Satellite measurements of aerosol do not contain information on the chemical composition needed to resolve anthropogenic vs. natural aerosol components. Besides, the same chemical species can have natural and anthropogenic origins. However the ability of the new satellite instruments (MODIS, MISR, POLDER) to distinguish fine from coarse aerosols over the oceans, can be used as a signature of the presence of anthropogenic component and used to measure the fraction of the aerosol originating from anthropogenic activity with an uncertainty of 10 percent for aerosol optical thickness larger than 0.1. We develop the methods and investigated it using model calculations (GOCART) and satellite data (MODIS). Preliminary application to 2 years of global MODIS data shows that 0.200.08 of the aerosol optical thickness and radiative effect has anthropogenic origin. The resultant aerosol forcing over cloud free oceans is 1.30.6 W/sq m, larger than model simulations. Further research until the presentation will probably modify these values.

Sensitivity of a radiative transfer model to the uncertainty in the aerosol optical depth used as input

NASA Astrophysics Data System (ADS)

Román, Roberto; Bilbao, Julia; de Miguel, Argimiro; Pérez-Burgos, Ana

2014-05-01

The radiative transfer models can be used to obtain solar radiative quantities in the Earth surface as the erythemal ultraviolet (UVER) irradiance, which is the spectral irradiance weighted with the erythemal (sunburn) action spectrum, and the total shortwave irradiance (SW; 305-2,8000 nm). Aerosol and atmospheric properties are necessary as inputs in the model in order to calculate the UVER and SW irradiances under cloudless conditions, however the uncertainty in these inputs causes another uncertainty in the simulations. The objective of this work is to quantify the uncertainty in UVER and SW simulations generated by the aerosol optical depth (AOD) uncertainty. The data from different satellite retrievals were downloaded at nine Spanish places located in the Iberian Peninsula: Total ozone column from different databases, spectral surface albedo and water vapour column from MODIS instrument, AOD at 443 nm and Angström Exponent (between 443 nm and 670 nm) from MISR instrument onboard Terra satellite, single scattering albedo from OMI instrument onboard Aura satellite. The obtained AOD at 443 nm data from MISR were compared with AERONET measurements in six Spanish sites finding an uncertainty in the AOD from MISR of 0.074. In this work the radiative transfer model UVSPEC/Libradtran (1.7 version) was used to obtain the SW and UVER irradiance under cloudless conditions for each month and for different solar zenith angles (SZA) in the nine mentioned locations. The inputs used for these simulations were monthly climatology tables obtained with the available data in each location. Once obtained the UVER and SW simulations, they were repeated twice but changing the AOD monthly values by the same AOD plus/minus its uncertainty. The maximum difference between the irradiance run with AOD and the irradiance run with AOD plus/minus its uncertainty was calculated for each month, SZA, and location. This difference was considered as the uncertainty on the model caused by the AOD uncertainty. The uncertainty in the simulated global SW and UVER varies with the location, but the behaviour is similar: high uncertainty in specific months. The averages of the uncertainty at the nine locations were calculated. Uncertainty in the global SW is lower than 5% for SZA values lower than 70º, and the uncertainty in global UVER is between 2 and 6%. The uncertainty in the direct and diffuse components is higher than in the global case for both SW and UVER irradiances, but a balance between the changes with AOD in direct and diffuse components provide a lower uncertainty in global SW and UVER irradiance. References Bilbao, J., Román, R., de Miguel, A., Mateos, D.: Long-term solar erythemal UV irradiance data reconstruction in Spain using a semiempirical method, J. Geophys. Res., 116, D22211, 2011. Kylling, A., Stamnes, K., Tsay, S. C.: A reliable and efficient two-stream algorithm for spherical radiative transfer: Documentation of acciracy in realistic layered media, J. Atmos. Chem, 21, 115-150, 1995. Ricchiazzi, P., Yang, S., Gautier, C., Sowle, D.: SBDART: A research and Teaching software tool for plane-parallel radiative transfer in the Earth's atmosphere, Bulletin of the American Meteorological

Measurement of optical to electrical and electrical to optical delays with ps-level uncertainty.

PubMed

Peek, H Z; Pinkert, T J; Jansweijer, P P M; Koelemeij, J C J

2018-05-28

We present a new measurement principle to determine the absolute time delay of a waveform from an optical reference plane to an electrical reference plane and vice versa. We demonstrate a method based on this principle with 2 ps uncertainty. This method can be used to perform accurate time delay determinations of optical transceivers used in fiber-optic time-dissemination equipment. As a result the time scales in optical and electrical domain can be related to each other with the same uncertainty. We expect this method will be a new breakthrough in high-accuracy time transfer and absolute calibration of time-transfer equipment.

Frequency accurate coherent electro-optic dual-comb spectroscopy in real-time.

PubMed

Martín-Mateos, Pedro; Jerez, Borja; Largo-Izquierdo, Pedro; Acedo, Pablo

2018-04-16

Electro-optic dual-comb spectrometers have proved to be a promising technology for sensitive, high-resolution and rapid spectral measurements. Electro-optic combs possess very attractive features like simplicity, reliability, bright optical teeth, and typically moderate but quickly tunable optical spans. Furthermore, in a dual-comb arrangement, narrowband electro-optic combs are generated with a level of mutual coherence that is sufficiently high to enable optical multiheterodyning without inter-comb stabilization or signal processing systems. However, this valuable tool still presents several limitations; for instance, on most systems, absolute frequency accuracy and long-term stability cannot be guaranteed; likewise, interferometer-induced phase noise restricts coherence time and limits the attainable signal-to-noise ratio. In this paper, we address these drawbacks and demonstrate a cost-efficient absolute electro-optic dual-comb instrument based on a frequency stabilization mechanism and a novel adaptive interferogram acquisition approach devised for electro-optic dual-combs capable of operating in real-time. The spectrometer, completely built from commercial components, provides sub-ppm frequency uncertainties and enables a signal-to-noise ratio of 10000 (intensity noise) in 30 seconds of integration time.

Optical Frequency Metrology of an Iodine-Stabilized He-Ne Laser Using the Frequency Comb of a Quantum-Interference-Stabilized Mode-Locked Laser

PubMed Central

Smith, Ryan P.; Roos, Peter A.; Wahlstrand, Jared K.; Pipis, Jessica A.; Rivas, Maria Belmonte; Cundiff, Steven T.

2007-01-01

We perform optical frequency metrology of an iodine-stabilized He-Ne laser using a mode-locked Ti:sapphire laser frequency comb that is stabilized using quantum interference of photocurrents in a semiconductor. Using this technique, we demonstrate carrier-envelope offset frequency fluctuations of less than 5 mHz using a 1 s gate time. With the resulting stable frequency comb, we measure the optical frequency of the iodine transition [127I2 R(127) 11-5 i component] to be 473 612 214 712.96 ± 0.66 kHz, well within the uncertainty of the CIPM recommended value. The stability of the quantum interference technique is high enough such that it does not limit the measurements. PMID:27110472

Single-ion, transportable optical atomic clocks

NASA Astrophysics Data System (ADS)

Delehaye, Marion; Lacroûte, Clément

2018-03-01

For the past 15 years, tremendous progress within the fields of laser stabilization, optical frequency combs and atom cooling and trapping have allowed the realization of optical atomic clocks with unrivaled performances. These instruments can perform frequency comparisons with fractional uncertainties well below ?, finding applications in fundamental physics tests, relativistic geodesy and time and frequency metrology. Even though most optical clocks are currently laboratory setups, several proposals for using these clocks for field measurements or within an optical clock network have been published, and most of time and frequency metrology institutes have started to develop transportable optical clocks. For the purpose of this special issue, we chose to focus on trapped-ion optical clocks. Even though their short-term fractional frequency stability is impaired by a lower signal-to-noise ratio, they offer a high potential for compactness: trapped ions demand low optical powers and simple loading schemes, and can be trapped in small vacuum chambers. We review recent advances on the clock key components, including ion trap and ultra-stable optical cavity, as well as existing projects and experiments which draw the picture of what future transportable, single-ion optical clocks may resemble.

Honing the accuracy of extreme-ultraviolet optical system testing: at-wavelength and visible-light measurements of the ETS Set-2 projection optic

NASA Astrophysics Data System (ADS)

Goldberg, Kenneth A.; Naulleau, Patrick P.; Bokor, Jeffrey; Chapman, Henry N.

2002-07-01

As the quality of optical systems for extreme ultraviolet lithography improves, high-accuracy wavefront metrology for alignment and qualification becomes ever more important. To enable the development of diffraction-limited EUV projection optics, visible-light and EUV interferometries must work in close collaboration. We present a detailed comparison of EUV and visible-light wavefront measurements performed across the field of view of a lithographic-quality EUV projection optical system designed for use in the Engineering Test Stand developed by the Virtual National Laboratory and the EUV Limited Liability Company. The comparisons reveal that the present level of RMS agreement lies in the 0.3-0.4-nm range. Astigmatism is the most significant aberration component for the alignment of this optical system; it is also the dominant term in the discrepancy, and the aberration with the highest measurement uncertainty. With EUV optical systems requiring total wavefront quality in the (lambda) EUV/50 range, and even higher surface-figure quality for the individual mirror elements, improved accuracy through future comparisons, and additional studies, are required.

Ocean color modeling: Parameterization and interpretation

NASA Astrophysics Data System (ADS)

Feng, Hui

The ocean color as observed near the water surface is determined mainly by dissolved and particulate substances, known as "optically-active constituents," in the upper water column. The goal of ocean color modeling is to interpret an ocean color spectrum quantitatively to estimate the suite of optically-active constituents near the surface. In recent years, ocean color modeling efforts have been centering upon three major optically-active constituents: chlorophyll concentration, colored dissolved organic matter, and scattering particulates. Many challenges are still being faced in this arena. This thesis generally addresses and deals with some critical issues in ocean color modeling. In chapter one, an extensive literature survey on ocean color modeling is given. A general ocean color model is presented to identify critical candidate uncertainty sources in modeling the ocean color. The goal for this thesis study is then defined as well as some specific objectives. Finally, a general overview of the dissertation is portrayed, defining each of the follow-up chapters to target some relevant objectives. In chapter two, a general approach is presented to quantify constituent concentration retrieval errors induced by uncertainties in inherent optical property (IOP) submodels of a semi-analytical forward model. Chlorophyll concentrations are retrieved by inverting a forward model with nonlinear IOPs. The study demonstrates how uncertainties in individual IOP submodels influence the accuracy of the chlorophyll concentration retrieval at different chlorophyll concentration levels. The important finding for this study shows that precise knowledge of spectral shapes of IOP submodels is critical for accurate chlorophyll retrieval, suggesting an improvement in retrieval accuracy requires precise spectral IOP measurements. In chapter three, three distinct inversion techniques, namely, nonlinear optimization (NLO), principal component analysis (PCA) and artificial neural network (ANN) are compared to assess their inversion performances to retrieve optically-active constituents for a complex nonlinear bio-optical system simulated by a semi-analytical ocean color model. A well-designed simulation scheme was implemented to simulate waters of different bio-optical complexity, and then the three inversion methods were applied to these simulated datasets for performance evaluation. In chapter four, an approach is presented for optimally parameterizing an irradiance reflectance model on the basis of a bio-optical dataset made at 45 stations in the Tokyo Bay and nearby regions between 1982 and 1984. (Abstract shortened by UMI.)

Simulating return signals of a spaceborne high-spectral resolution lidar channel at 532 nm

NASA Astrophysics Data System (ADS)

Xiao, Yu; Binglong, Chen; Min, Min; Xingying, Zhang; Lilin, Yao; Yiming, Zhao; Lidong, Wang; Fu, Wang; Xiaobo, Deng

2018-06-01

High spectral resolution lidar (HSRL) system employs a narrow spectral filter to separate the particulate (cloud/aerosol) and molecular scattering components in lidar return signals, which improves the quality of the retrieved cloud/aerosol optical properties. To better develop a future spaceborne HSRL system, a novel simulation technique was developed to simulate spaceborne HSRL return signals at 532 nm using the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) cloud/aerosol extinction coefficients product and numerical weather prediction data. For validating simulated data, a mathematical particulate extinction coefficient retrieval method for spaceborne HSRL return signals is described here. We compare particulate extinction coefficient profiles from the CALIPSO operational product with simulated spaceborne HSRL data. Further uncertainty analysis shows that relative uncertainties are acceptable for retrieving the optical properties of cloud and aerosol. The final results demonstrate that they agree well with each other. It indicates that the return signals of the spaceborne HSRL molecular channel at 532 nm will be suitable for developing operational algorithms supporting a future spaceborne HSRL system.

Critical dimensional linewidth calibration using UV microscope and laser interferometry

NASA Astrophysics Data System (ADS)

Li, Qi; Gao, Si-tian; Li, Wei; Lu, Ming-zhen; Zhang, Ming-kai

2013-10-01

In order to calibrate the critical dimensional (CD) uncertainty of lithography masks in semiconductor manufacturing, NIM is building a two dimensional metrological UV microscope which has traceable measurement ability for nanometer linewidths and pitches. The microscope mainly consists of UV light receiving components, piezoelectric ceramics (PZT) driven stage and interferometer calibration framework. In UV light receiving components they include all optical elements on optical path. The UV light originates from Köhler high aperture transmit/reflect illumination sources; then goes through objective lens to UV splitting optical elements; after that, one part of light attains UV camera for large range calibration, the other part of light passes through a three dimensional adjusted pinhole and is collected by PMT for nanoscale scanning. In PZT driven stage, PZT stick actuators with closed loop control are equipped to push/pull a flexural hinge based platform. The platform has a novel designed compound flexural hinges which nest separate X, Y direction moving mechanisms within one layer but avoiding from mutual cross talk, besides this, the hinges also contain leverage structures to amplify moving distance. With these designs, the platform can attain 100 μm displacement ranges as well as 1 nm resolution. In interferometer framework a heterodyne multi-pass interferometer is mounted on the platform, which measures X-Y plane movement and Z axis rotation, through reference mirror mounted on objective lens tube and Zerodur mirror mounted on PZT platform, the displacement is traced back to laser wavelength. When development is finished, the apparatus can offer the capability to calibrate one dimensional linewidths and two dimensional pitches ranging from 200nm to 50μm with expanded uncertainty below 20nm.

A Case For Free-free Absorption In The GPS Sources 1321+410 And 0026+346

NASA Astrophysics Data System (ADS)

Marr, Jonathan M.; Perry, T. M.; Read, J. W.; Taylor, G. B.

2010-05-01

We report on the results of VLBI observations of two gigahertz-peaked spectrum sources, 1321+410 and 0026+346, at five frequencies bracketing the spectral peaks. By comparing the three lower-frequency flux-density maps with extrapolations of the high frequency spectra we obtained maps of the optical depths as a function of frequency. The morphologies of the optical depth maps of 1321+410, at all frequencies, are strikingly uniform, consistent with there being a foreground screen of absorbing gas. We also find that the flux densities across the map fit free-free absorption spectra within the uncertainties. The required free-free optical depths are satisfied with reasonable gas parameters (ne 4000 cm-3, T 104 K, and L 1 pc). We conclude that the case for free-free absorption in 1321+410 is strong. In 0026+346, there is a compact feature with an inverted spectrum at the highest frequencies which we take to be the core. The optical depth maps, even excluding the possible core component, exhibit a noticeable amount of structure, but the morphology does not correlate with that in the flux-density maps, as would be expected if the absorption was due to synchrotron self-absorption. Additionally, the spectra (except at the core component) are consistent with free-free absorption, to within the uncertainties, and require column depths about one half of that in 1321+410. We conclude that free-free absorption by a relatively thin amount of gas with structure apparent on the scale of our maps in 0026+346 is likely, although the case is weaker than in 1321+410. This research was supported by an award from the Research Corporation, a NASA NY Space Grant, and by a Booth-Ferris Research Fellowship. The VLBA is operated by the National Radio Astronomy Observatory, a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

Modeling and Experimental Study of Fracture-Based Wellbore Strengthening

NASA Astrophysics Data System (ADS)

Zhong, Ruizhi

Measuring physical dimensions has always been one of the challenges for optical metrology. Specifically, the thickness is often a prerequisite piece of information for other optical properties when characterizing components and materials. For example, when measuring the index of refraction of materials using interferometric methods, the direct measurement is optical path length difference. To acquire index of refraction with high accuracy, the thickness must be predetermined with correspondingly high accuracy as well. In this dissertation, a prototype low-coherence interferometer system is developed through several design iterations to measure the absolute thickness map of a plane-parallel samples in a nondestructive manner. The prototype system is built with all off-the-shelf components in a configuration that combines a Twyman-Green interferometer and a Sagnac interferometer. The repeatability and accuracy of the measured thickness are characterized to be less than one micrometer. Based on the information acquired from the development of the prototype system, a permanent low-coherence interferometer system is designed and built to achieve a higher accuracy in thickness measurements, on the level of a hundred nanometers. A comprehensive uncertainty model is established for the thickness measurement using the low-coherence interferometer system. Additionally, this system is also capable of measuring the topography of both surfaces of the sample, as well as the wedge of the sample. This low-coherence dimensional metrology uses only the reflection signals from the sample surfaces. Thus, the measured physical dimensions are independent of the index of refraction, transparency, transmission, or homogeneity of the sample. In addition, a laser Sagnac interferometer is designed and built by repurposing the test arm of the low-coherence interferometer. The laser Sagnac interferometer provides a non-contact bulk index of refraction metrology for solid materials. The uncertainty model for the index of refraction measurement is detailed with analytical solutions. The laser Sagnac interferometer requires relatively simple sample preparation and fast turn-around time, which is suitable for applications in optical material research.

Frequency Comparison of [Formula: see text] Ion Optical Clocks at PTB and NPL via GPS PPP.

PubMed

Leute, J; Huntemann, N; Lipphardt, B; Tamm, Christian; Nisbet-Jones, P B R; King, S A; Godun, R M; Jones, J M; Margolis, H S; Whibberley, P B; Wallin, A; Merimaa, M; Gill, P; Peik, E

2016-07-01

We used precise point positioning, a well-established GPS carrier-phase frequency transfer method to perform a direct remote comparison of two optical frequency standards based on single laser-cooled [Formula: see text] ions operated at the National Physical Laboratory (NPL), U.K. and the Physikalisch-Technische Bundesanstalt (PTB), Germany. At both institutes, an active hydrogen maser serves as a flywheel oscillator which is connected to a GPS receiver as an external frequency reference and compared simultaneously to a realization of the unperturbed frequency of the (2)S1/2(F=0)-(2)D3/2(F=2) electric quadrupole transition in [Formula: see text] via an optical femtosecond frequency comb. To profit from long coherent GPS-link measurements, we extrapolate the fractional frequency difference over the various data gaps in the optical clock to maser comparisons which introduces maser noise to the frequency comparison but improves the uncertainty from the GPS-link instability. We determined the total statistical uncertainty consisting of the GPS-link uncertainty and the extrapolation uncertainties for several extrapolation schemes. Using the extrapolation scheme with the smallest combined uncertainty, we find a fractional frequency difference [Formula: see text] of -1.3×10(-15) with a combined uncertainty of 1.2×10(-15) for a total measurement time of 67 h. This result is consistent with an agreement of the frequencies realized by both optical clocks and with recent absolute frequency measurements against caesium fountain clocks within the corresponding uncertainties.

Robustness of Flexible Systems With Component-Level Uncertainties

NASA Technical Reports Server (NTRS)

Maghami, Peiman G.

2000-01-01

Robustness of flexible systems in the presence of model uncertainties at the component level is considered. Specifically, an approach for formulating robustness of flexible systems in the presence of frequency and damping uncertainties at the component level is presented. The synthesis of the components is based on a modifications of a controls-based algorithm for component mode synthesis. The formulation deals first with robustness of synthesized flexible systems. It is then extended to deal with global (non-synthesized ) dynamic models with component-level uncertainties by projecting uncertainties from component levels to system level. A numerical example involving a two-dimensional simulated docking problem is worked out to demonstrate the feasibility of the proposed approach.

Design and Characterization of the 4STAR Sun-Sky Spectrometer with Results from 4- Way Intercomparison of 4STAR, AATS-14, Prede, and Cimel Photometers at Mauna Loa Observatory.

NASA Astrophysics Data System (ADS)

Flynn, C. J.; Dunagan, S. E.; Johnson, R. R.; Schmid, B.; Shinozuka, Y.; Ramachandran, S.; Livingston, J. M.; Russell, P. B.; Redemann, J.; Tran, A. K.; Holben, B. N.

2008-12-01

Uncertainties in radiative forcing of climate are still dominated by uncertainties in forcing by aerosols. Aerosols impact the radiation balance in three primary ways: the direct effect through scattering and absorption of radiation, the indirect effect by acting as cloud condensation nuclei affecting cloud optical depth and longevity, and the semi-direct effect affecting cloud formation and longevity through heating and thermodynamics. An active collaboration between the Pacific Northwest National Laboratory (PNNL), National Aeronautics and Space Administration (NASA) Ames Research Center (ARC), and NASA Goddard Space Flight Center (GSFC) is advancing new instrument concepts with application to reducing these aerosol uncertainties. The concept of 4STAR (Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research) combines airborne sun tracking capabilities of the Ames Airborne Tracking Sun Photometer (AATS-14) and Aeronet-like sky scanning capability with state-of-the-art monolithic spectrometry. The overall science goal for the new instruments is to improve knowledge of atmospheric constituents and their links to climate. The high-resolution spectral capability will improve retrievals of gas constituents (e.g., H2O, O3, and NO2) and thereby improve determination of aerosol properties as residual components of the total optical depth. The sky scanning capability will enable retrievals of aerosol type (via complex refractive index and shape) and aerosol size distribution extending to larger sizes than attainable by direct-beam sun photometry alone. Additional technical goals are to reduce instrument size, weight, and power requirements while increasing autonomy and component modularity to permit operation on a wide range of aircraft including unmanned aerial vehicles (UAVs). To investigate techniques to accomplish these goals, we developed a ground-based prototype, 4STAR-Ground. The 4STAR-Ground operating performance has been characterized in many tests including field of view (FOV) scans, repeatability testing of the fiber optic coupler, calibration of diffuse sky radiance with integrating sphere, and calibration of solar irradiance via Langley retrievals. Recent results from an intercomparison on Mauna Loa Observatory involving 4STAR, AATS-14, AERONET Cimel sun-sky photometers, and a Prede sun-sky photometer will be presented.

The Near-Earth Meteoroid Flux, Speed Distribution, and Uncertainty

NASA Technical Reports Server (NTRS)

Moorhead, Althea; Cooke, William J.; Brown, Peter G.; Campbell-Brown, Margaret; Moser, Danielle E.

2016-01-01

Meteoroids are known to pose a threat to spacecraft; they can puncture components, disturb spacecraft attitude, and possibly create secondary electrical effects. Accurate environment models are therefore critical for mitigating meteoroid-related risks. While there are several meteoroid environment models available for assessing spacecraft risk, the uncertainties associated with these models are not well understood. Because meteoroid properties are derived from indirect observations such as meteors and impact craters, the uncertainty in the meteoroid flux is potentially quite large. We combine existing meteoroid flux measurements with new radar and optical meteor data to improve our characterization of the meteoroid flux onto the Earth and its velocity distribution. We use data extracted from the NASA all-sky network, the Canadian Automated Meteor Observatory, and the Canadian Meteor Orbit Radar. We improve our characterization of the observed meteoroid speed distribution by incorporating modern descriptions of the ionization efficiency (e.g., Thomas et al., 2016). We also present estimates of the uncertainties associated with our meteoroid flux distribution. Finally, we discuss the implications for spacecraft. Our model is constrained by the cratering rate on the space-facing surface of LDEF, and thus the risk posed to spacecraft by meteoroid-induced physical damage is the least uncertain component of our model. Other sources of risk, however, may vary. For instance, a lower average meteoroid speed would require a higher meteoroid mass flux in order to match the LDEF crater counts, leading to higher predicted rates of attitude disturbances.

Disturbance, the uncertainty principle and quantum optics

NASA Technical Reports Server (NTRS)

Martens, Hans; Demuynck, Willem M.

1993-01-01

It is shown how a disturbance-type uncertainty principle can be derived from an uncertainty principle for joint measurements. To achieve this, we first clarify the meaning of 'inaccuracy' and 'disturbance' in quantum mechanical measurements. The case of photon number and phase is treated as an example, and it is applied to a quantum non-demolition measurement using the optical Kerr effect.

A methodology for calibration of hyperspectral and multispectral satellite data in coastal areas

NASA Astrophysics Data System (ADS)

Pennucci, Giuliana; Fargion, Giulietta; Alvarez, Alberto; Trees, Charles; Arnone, Robert

2012-06-01

The objective of this work is to determine the location(s) in any given oceanic area during different temporal periods where in situ sampling for Calibration/Validation (Cal/Val) provides the best capability to retrieve accurate radiometric and derived product data (lowest uncertainties). We present a method to merge satellite imagery with in situ measurements, to determine the best in situ sampling strategy suitable for satellite Cal/Val and to evaluate the present in situ locations through uncertainty indices. This analysis is required to determine if the present in situ sites are adequate for assessing uncertainty and where additional sites and ship programs should be located to improve Calibration/Validation (Cal/Val) procedures. Our methodology uses satellite acquisitions to build a covariance matrix encoding the spatial-temporal variability of the area of interest. The covariance matrix is used in a Bayesian framework to merge satellite and in situ data providing a product with lower uncertainty. The best in situ location for Cal/Val is then identified by using a design principle (A-optimum design) that looks for minimizing the estimated variance of the merged products. Satellite products investigated in this study include Ocean Color water leaving radiance, chlorophyll, and inherent and apparent optical properties (retrieved from MODIS and VIIRS). In situ measurements are obtained from systems operated on fixed deployment platforms (e.g., sites of the Ocean Color component of the AErosol RObotic NETwork- AERONET-OC), moorings (e.g, Marine Optical Buoy-MOBY), ships or autonomous vehicles (such as Autonomous Underwater Vehicles and/or Gliders).

Maritime Aerosol Network as a Component of AERONET - a Useful Tool for Evaluation of the Global Sea-Salt Aerosol Distribution

NASA Astrophysics Data System (ADS)

Smirnov, A.; Holben, B. N.; Kinne, S.; Nelson, N. B.; Stenchikov, G. L.; Broccardo, S. P.; Sowers, D.; Lobecker, E.; Ondrusek, M.; Zielinski, T. P.; Gray, L. M.; Frouin, R.; Radionov, V. F.; Smyth, T. J.; Zibordi, G.; Heller, M. I.; Slabakova, V.; Krüger, K.; Reid, E. A.; Istomina, L.; Vandermeulen, R. A.; O'Neill, N. T.; Levy, G.; Giles, D. M.; Slutsker, I.; Sorokin, M. G.; Eck, T. F.

2016-02-01

Sea-salt aerosol plays an important role in radiation balance and chemistry of marine atmosphere. Sea-salt production depends on various factors. There is a significant uncertainty in the parametrization of the sea-salt production and budget. Ship-based aerosol optical depth (AOD) measurements can be used as an important validation tool for various global models and in-situ measurements. The paper presents the current status of the Maritime Aerosol Network (MAN) which is a component of Aerosol Robotic Network. Since 2006 over 300 cruises were completed and data archive of more than 5500 measurement days is accessible at http://aeronet.gsfc.nasa.gov/new_web/maritime_aerosol_network.html . AOD measurements from ships of opportunity complemented island-based AERONET measurements and provided important reference points for satellite retrieved and modelled AOD climatology over the oceans. The program exemplifies mutually beneficial international, multi-agency effort in atmospheric aerosol optical studies over the oceans.

Development of automated endoscopes for dimensional micro-measurements

NASA Astrophysics Data System (ADS)

Hrebabetzky, Frank

2013-04-01

Increasing demands for product quality and outsourcing of production in the automobile industry lead to in­ creasingly tight tolerances for the components. In the area of metal-mechanics these are largely dimensional and require frequently uncertainties in the micron region. For optical instruments this means microscopical resolu­ tion. Dimensional measurement with uncertainties of some microns is nothing new, state of the art equipment in fact goes far below. The task becomes difficult if the measurements have to be carried out in an industrial production environment - and deep inside a bore hole. This paper describes the development of an automatic measurement system for internal dimensions of brake master cylinders, specifically the development of endoscopes, illuminations for edge detection, and integration with other sensors, actuators and controllers. The most demanding part was the endoscope development, because, surprisingly, no commercial product for microscopic view and precision measurements was found on the market. As the market for such measurement machines is very small, and as the requirements were different for each endoscope, the budget allowed only the development of prototypes, using readily available optical components. Borders between faces with different orientation of metallic structures can be difficult do detect. A satisfactory metrological performance can be achieved only with carefully shaped illumination, even if the source is a simple LED (light emitting diode). The automation was responsible for the largest part of the overall cost, coming from the desire for a high throughput of the measurement machine, even when operated by not highly qualified personnel. With the safety requirements satisfied, such a device ends up as a pretty complex equipment. Nevertheless, these aspects will be mentioned only for completeness, because standard components and methods were applied.

Accuracy assessment for a multi-parameter optical calliper in on line automotive applications

NASA Astrophysics Data System (ADS)

D'Emilia, G.; Di Gasbarro, D.; Gaspari, A.; Natale, E.

2017-08-01

In this work, a methodological approach based on the evaluation of the measurement uncertainty is applied to an experimental test case, related to the automotive sector. The uncertainty model for different measurement procedures of a high-accuracy optical gauge is discussed in order to individuate the best measuring performances of the system for on-line applications and when the measurement requirements are becoming more stringent. In particular, with reference to the industrial production and control strategies of high-performing turbochargers, two uncertainty models are proposed, discussed and compared, to be used by the optical calliper. Models are based on an integrated approach between measurement methods and production best practices to emphasize their mutual coherence. The paper shows the possible advantages deriving from the considerations that the measurement uncertainty modelling provides, in order to keep control of the uncertainty propagation on all the indirect measurements useful for production statistical control, on which basing further improvements.

Parameter Uncertainties for a 10-Meter Ground-Based Optical Reception Station

NASA Technical Reports Server (NTRS)

Shaik, K.

1990-01-01

Performance uncertainties for a 10-m optical reception station may arise from the nature of the communications channel or from a specific technology choice. Both types of uncertainties are described in this article to develop an understanding of the limitations imposed by them and to provide a rational basis for making technical decisions. The performance at night will be considerably higher than for daytime reception.

Advances in radiometry for ocean color

USGS Publications Warehouse

Brown, S.W.; Clark, D.K.; Johnson, B.C.; Yoon, H.; Lykke, K.R.; Flora, S.J.; Feinholz, M.E.; Souaidia, N.; Pietras, C.; Stone, T.C.; Yarbrough, M.A.; Kim, Y.S.; Barnes, R.A.; Mueller, J.L.

2004-01-01

We have presented a number of recent developments in radiometry that directly impact the uncertainties achievable in ocean-color research. Specifically, a new (2000) U. S. national irradiance scale, a new LASER-based facility for irradiance and radiance responsivity calibrations, and applications of the LASER facility for the calibration of sun photometers and characterization of spectrographs were discussed. For meaningful long-time-series global chlorophyll-a measurements, all instruments involved in radiometric measurements, including satellite sensors, vicarious calibration sensors, sensors used in the development of bio-optical algorithms and atmospheric characterization need to be fully characterized and corrected for systematic errors, including, but not limited to, stray light. A unique, solid-state calibration source is under development to reduce the radiometric uncertainties in ocean color instruments, in particular below 400 nm. Lunar measurements for trending of on-orbit sensor channel degradation were described. Unprecedented assessments, within 0.1 %, of temporal stability and drift in a satellite sensor's radiance responsivity are achievable with this approach. These developments advance the field of ocean color closer to the desired goal of reducing the uncertainty in the fundamental radiometry to a small component of the overall uncertainty in the derivation of remotely sensed ocean-color data products such as chlorophyll a.

The Community Cloud retrieval for CLimate (CC4CL) - Part 2: The optimal estimation approach

NASA Astrophysics Data System (ADS)

McGarragh, Gregory R.; Poulsen, Caroline A.; Thomas, Gareth E.; Povey, Adam C.; Sus, Oliver; Stapelberg, Stefan; Schlundt, Cornelia; Proud, Simon; Christensen, Matthew W.; Stengel, Martin; Hollmann, Rainer; Grainger, Roy G.

2018-06-01

The Community Cloud retrieval for Climate (CC4CL) is a cloud property retrieval system for satellite-based multispectral imagers and is an important component of the Cloud Climate Change Initiative (Cloud_cci) project. In this paper we discuss the optimal estimation retrieval of cloud optical thickness, effective radius and cloud top pressure based on the Optimal Retrieval of Aerosol and Cloud (ORAC) algorithm. Key to this method is the forward model, which includes the clear-sky model, the liquid water and ice cloud models, the surface model including a bidirectional reflectance distribution function (BRDF), and the "fast" radiative transfer solution (which includes a multiple scattering treatment). All of these components and their assumptions and limitations will be discussed in detail. The forward model provides the accuracy appropriate for our retrieval method. The errors are comparable to the instrument noise for cloud optical thicknesses greater than 10. At optical thicknesses less than 10 modeling errors become more significant. The retrieval method is then presented describing optimal estimation in general, the nonlinear inversion method employed, measurement and a priori inputs, the propagation of input uncertainties and the calculation of subsidiary quantities that are derived from the retrieval results. An evaluation of the retrieval was performed using measurements simulated with noise levels appropriate for the MODIS instrument. Results show errors less than 10 % for cloud optical thicknesses greater than 10. Results for clouds of optical thicknesses less than 10 have errors up to 20 %.

Pilot, a balloon borne experiment underground tests

NASA Astrophysics Data System (ADS)

Engel, C.; Marty, C.; Mot, B.; Bernard, J.-Ph.; Ristorcelli, I.; Otrio, G.; Leriche, B.; Longval, Y.; Pajot, F.; Roudil, G.; Caillat, A.; Dubois, J. P.; Bouzit, M.; Buttice, V.; Camus, T.

2017-11-01

PILOT is a balloon borne experiment, which will measure the polarized emission of dust grains, in the interstellar medium, in the sub millimeter range (with two photometric channels centered at 240 and 550 μm). The primary and secondary mirror must be positioned with accuracies better than 0.6 mm and 0.06°. These tolerances include environmental conditions (mainly gravity and thermo-elastic effects), uncertainties on alignments, and uncertainties on the dilatation coefficient. In order to respect these tolerances, we need precise characterization of each optical component. The characterization of the primary mirror and the integrated instrument is performed using a dedicated submillimeter test bench. A brief description of the scientific objectives and instrumental concept is given in the first part. We present, in the second and in the third part, the status of these ground tests, first results and planned tests.

Mid-frequency Band Dynamics of Large Space Structures

NASA Technical Reports Server (NTRS)

Coppolino, Robert N.; Adams, Douglas S.

2004-01-01

High and low intensity dynamic environments experienced by a spacecraft during launch and on-orbit operations, respectively, induce structural loads and motions, which are difficult to reliably predict. Structural dynamics in low- and mid-frequency bands are sensitive to component interface uncertainty and non-linearity as evidenced in laboratory testing and flight operations. Analytical tools for prediction of linear system response are not necessarily adequate for reliable prediction of mid-frequency band dynamics and analysis of measured laboratory and flight data. A new MATLAB toolbox, designed to address the key challenges of mid-frequency band dynamics, is introduced in this paper. Finite-element models of major subassemblies are defined following rational frequency-wavelength guidelines. For computational efficiency, these subassemblies are described as linear, component mode models. The complete structural system model is composed of component mode subassemblies and linear or non-linear joint descriptions. Computation and display of structural dynamic responses are accomplished employing well-established, stable numerical methods, modern signal processing procedures and descriptive graphical tools. Parametric sensitivity and Monte-Carlo based system identification tools are used to reconcile models with experimental data and investigate the effects of uncertainties. Models and dynamic responses are exported for employment in applications, such as detailed structural integrity and mechanical-optical-control performance analyses.

Helium Mass Spectrometer Leak Detection: A Method to Quantify Total Measurement Uncertainty

NASA Technical Reports Server (NTRS)

Mather, Janice L.; Taylor, Shawn C.

2015-01-01

In applications where leak rates of components or systems are evaluated against a leak rate requirement, the uncertainty of the measured leak rate must be included in the reported result. However, in the helium mass spectrometer leak detection method, the sensitivity, or resolution, of the instrument is often the only component of the total measurement uncertainty noted when reporting results. To address this shortfall, a measurement uncertainty analysis method was developed that includes the leak detector unit's resolution, repeatability, hysteresis, and drift, along with the uncertainty associated with the calibration standard. In a step-wise process, the method identifies the bias and precision components of the calibration standard, the measurement correction factor (K-factor), and the leak detector unit. Together these individual contributions to error are combined and the total measurement uncertainty is determined using the root-sum-square method. It was found that the precision component contributes more to the total uncertainty than the bias component, but the bias component is not insignificant. For helium mass spectrometer leak rate tests where unit sensitivity alone is not enough, a thorough evaluation of the measurement uncertainty such as the one presented herein should be performed and reported along with the leak rate value.

A fast high-precision six-degree-of-freedom relative position sensor

NASA Astrophysics Data System (ADS)

Hughes, Gary B.; Macasaet, Van P.; Griswold, Janelle; Sison, Claudia A.; Lubin, Philip; Meinhold, Peter; Suen, Jonathan; Brashears, Travis; Zhang, Qicheng; Madajian, Jonathan

2016-03-01

Lasers are commonly used in high-precision measurement and profiling systems. Some laser measurement systems are based on interferometry principles, and others are based on active triangulation, depending on requirements of the application. This paper describes an active triangulation laser measurement system for a specific application wherein the relative position of two fixed, rigid mechanical components is to be measured dynamically with high precision in six degrees of freedom (DOF). Potential applications include optical systems with feedback to control for mechanical vibration, such as target acquisition devices with multiple focal planes. The method uses an array of several laser emitters mounted on one component. The lasers are directed at a reflective surface on the second component. The reflective surface consists of a piecewise-planar pattern such as a pyramid, or more generally a curved reflective surface such as a hyperbolic paraboloid. The reflected spots are sensed at 2-dimensional photodiode arrays on the emitter component. Changes in the relative position of the emitter component and reflective surface will shift the location of the reflected spots within photodiode arrays. Relative motion in any degree of freedom produces independent shifts in the reflected spot locations, allowing full six-DOF relative position determination between the two component positions. Response time of the sensor is limited by the read-out rate of the photodiode arrays. Algorithms are given for position determination with limits on uncertainty and sensitivity, based on laser and spot-sensor characteristics, and assuming regular surfaces. Additional uncertainty analysis is achievable for surface irregularities based on calibration data.

Precision alignment and calibration of optical systems using computer generated holograms

NASA Astrophysics Data System (ADS)

Coyle, Laura Elizabeth

As techniques for manufacturing and metrology advance, optical systems are being designed with more complexity than ever before. Given these prescriptions, alignment and calibration can be a limiting factor in their final performance. Computer generated holograms (CGHs) have several unique properties that make them powerful tools for meeting these demanding tolerances. This work will present three novel methods for alignment and calibration of optical systems using computer generated holograms. Alignment methods using CGHs require that the optical wavefront created by the CGH be related to a mechanical datum to locate it space. An overview of existing methods is provided as background, then two new alignment methods are discussed in detail. In the first method, the CGH contact Ball Alignment Tool (CBAT) is used to align a ball or sphere mounted retroreflector (SMR) to a Fresnel zone plate pattern with micron level accuracy. The ball is bonded directly onto the CGH substrate and provides permanent, accurate registration between the optical wavefront and a mechanical reference to locate the CGH in space. A prototype CBAT was built and used to align and bond an SMR to a CGH. In the second method, CGH references are used to align axi-symmetric optics in four degrees of freedom with low uncertainty and real time feedback. The CGHs create simultaneous 3D optical references where the zero order reflection sets tilt and the first diffracted order sets centration. The flexibility of the CGH design can be used to accommodate a wide variety of optical systems and maximize sensitivity to misalignments. A 2-CGH prototype system was aligned multiplied times and the alignment uncertainty was quantified and compared to an error model. Finally, an enhanced calibration method is presented. It uses multiple perturbed measurements of a master sphere to improve the calibration of CGH-based Fizeau interferometers ultimately measuring aspheric test surfaces. The improvement in the calibration is a function of the interferometer error and the aspheric departure of the desired test surface. This calibration is most effective at reducing coma and trefoil from figure error or misalignments of the interferometer components. The enhanced calibration can reduce overall measurement uncertainty or allow the budgeted error contribution from another source to be increased. A single set of sphere measurements can be used to calculate calibration maps for closely related aspheres, including segmented primary mirrors for telescopes. A parametric model is developed and compared to the simulated calibration of a case study interferometer.

Estimates of the Spectral Aerosol Single Sea Scattering Albedo and Aerosol Radiative Effects during SAFARI 2000

NASA Technical Reports Server (NTRS)

Bergstrom, Robert W.; Pilewskie, Peter; Schmid, Beat; Russell, Philip B.

2003-01-01

Using measurements of the spectral solar radiative flux and optical depth for 2 days (24 August and 6 September 2000) during the SAFARI 2000 intensive field experiment and a detailed radiative transfer model, we estimate the spectral single scattering albedo of the aerosol layer. The single scattering albedo is similar on the 2 days even though the optical depth for the aerosol layer was quite different. The aerosol single scattering albedo was between 0.85 and 0.90 at 350 nm, decreasing to 0.6 in the near infrared. The magnitude and decrease with wavelength of the single scattering albedo are consistent with the absorption properties of small black carbon particles. We estimate the uncertainty in the single scattering albedo due to the uncertainty in the measured fractional absorption and optical depths. The uncertainty in the single scattering albedo is significantly less on the high-optical-depth day (6 September) than on the low-optical-depth day (24 August). On the high-optical-depth day, the uncertainty in the single scattering albedo is 0.02 in the midvisible whereas on the low-optical-depth day the uncertainty is 0.08 in the midvisible. On both days, the uncertainty becomes larger in the near infrared. We compute the radiative effect of the aerosol by comparing calculations with and without the aerosol. The effect at the top of the atmosphere (TOA) is to cool the atmosphere by 13 W/sq m on 24 August and 17 W/sq m on 6 September. The effect on the downward flux at the surface is a reduction of 57 W/sq m on 24 August and 200 W/sq m on 6 September. The aerosol effect on the downward flux at the surface is in good agreement with the results reported from the Indian Ocean Experiment (INDOEX).

A Bayesian Network Based Global Sensitivity Analysis Method for Identifying Dominant Processes in a Multi-physics Model

NASA Astrophysics Data System (ADS)

Dai, H.; Chen, X.; Ye, M.; Song, X.; Zachara, J. M.

2016-12-01

Sensitivity analysis has been an important tool in groundwater modeling to identify the influential parameters. Among various sensitivity analysis methods, the variance-based global sensitivity analysis has gained popularity for its model independence characteristic and capability of providing accurate sensitivity measurements. However, the conventional variance-based method only considers uncertainty contribution of single model parameters. In this research, we extended the variance-based method to consider more uncertainty sources and developed a new framework to allow flexible combinations of different uncertainty components. We decompose the uncertainty sources into a hierarchical three-layer structure: scenario, model and parametric. Furthermore, each layer of uncertainty source is capable of containing multiple components. An uncertainty and sensitivity analysis framework was then constructed following this three-layer structure using Bayesian network. Different uncertainty components are represented as uncertain nodes in this network. Through the framework, variance-based sensitivity analysis can be implemented with great flexibility of using different grouping strategies for uncertainty components. The variance-based sensitivity analysis thus is improved to be able to investigate the importance of an extended range of uncertainty sources: scenario, model, and other different combinations of uncertainty components which can represent certain key model system processes (e.g., groundwater recharge process, flow reactive transport process). For test and demonstration purposes, the developed methodology was implemented into a test case of real-world groundwater reactive transport modeling with various uncertainty sources. The results demonstrate that the new sensitivity analysis method is able to estimate accurate importance measurements for any uncertainty sources which were formed by different combinations of uncertainty components. The new methodology can provide useful information for environmental management and decision-makers to formulate policies and strategies.

Theoferometer for the Construction of Precision Optomechanical Assemblies

NASA Technical Reports Server (NTRS)

Korzun, Ashley M.

2006-01-01

The increasing difficulty of metrology requirements on projects involving optics and the alignment of instrumentation on spacecraft has reached a turning point. Requirements as low as 0.1 arcseconds for the static, rotational alignment of components within a coordinate system cannot be met with a theodolite, the alignment tool currently in use. A "theoferometer" is an interferometer mounted on a rotation stage with degrees of freedom in azimuth and elevation for metrology and alignment applications. The success of a prototype theoferometer in approaching these metrology requirements led to a redesign stressing mechanical, optical, and software changes to increase the sensitivity and portability of the unit. This paper covers the improvements made to the first prototype theoferometer, characteristic testing, and demonstration of the redesigned theoferometer s capabilities as a "theodolite replacement" and low-uncertainty metrology tool.

Uncertainties of optical parameters and their propagations in an analytical ocean color inversion algorithm.

PubMed

Lee, ZhongPing; Arnone, Robert; Hu, Chuanmin; Werdell, P Jeremy; Lubac, Bertrand

2010-01-20

Following the theory of error propagation, we developed analytical functions to illustrate and evaluate the uncertainties of inherent optical properties (IOPs) derived by the quasi-analytical algorithm (QAA). In particular, we evaluated the effects of uncertainties of these optical parameters on the inverted IOPs: the absorption coefficient at the reference wavelength, the extrapolation of particle backscattering coefficient, and the spectral ratios of absorption coefficients of phytoplankton and detritus/gelbstoff, respectively. With a systematically simulated data set (46,200 points), we found that the relative uncertainty of QAA-derived total absorption coefficients in the blue-green wavelengths is generally within +/-10% for oceanic waters. The results of this study not only establish theoretical bases to evaluate and understand the effects of the various variables on IOPs derived from remote-sensing reflectance, but also lay the groundwork to analytically estimate uncertainties of these IOPs for each pixel. These are required and important steps for the generation of quality maps of IOP products derived from satellite ocean color remote sensing.

Statistics Analysis of the Uncertainties in Cloud Optical Depth Retrievals Caused by Three-Dimensional Radiative Effects

NASA Technical Reports Server (NTRS)

Varnai, Tamas; Marshak, Alexander

2000-01-01

This paper presents a simple approach to estimate the uncertainties that arise in satellite retrievals of cloud optical depth when the retrievals use one-dimensional radiative transfer theory for heterogeneous clouds that have variations in all three dimensions. For the first time, preliminary error bounds are set to estimate the uncertainty of cloud optical depth retrievals. These estimates can help us better understand the nature of uncertainties that three-dimensional effects can introduce into retrievals of this important product of the MODIS instrument. The probability distribution of resulting retrieval errors is examined through theoretical simulations of shortwave cloud reflection for a wide variety of cloud fields. The results are used to illustrate how retrieval uncertainties change with observable and known parameters, such as solar elevation or cloud brightness. Furthermore, the results indicate that a tendency observed in an earlier study, clouds appearing thicker for oblique sun, is indeed caused by three-dimensional radiative effects.

Potential improvements aimed at high precision δ13C isotopic ratio determinations in CO2 mixtures using optical absorption spectrometry.

PubMed

Koulikov, Serguei; Assonov, Sergey; Fajgelj, Ales; Tans, Pieter

2018-07-01

The manuscript explores some advantages and limitations of laser based optical spectroscopy, aimed at achieving robust, high-reproducibility 13 C 16 O 2 and 12 C 16 O 2 ratio determinations on the VPDB-CO 2 δ 13 C scale by measuring the absorbance of line pairs of 13 C 16 O 2 and 12 C 16 O 2 . In particular, the sensitivities of spectroscopic lines to both pressure (P) and temperature (T) are discussed. Based on the considerations and estimations presented, a level of reproducibility of the 13 C 16 O 2 / 12 C 16 O 2 ratio determinations may be achieved of about 10 -6 . Thus one may establish an optical spectroscopic measurement technique for robust, high-precision 13 C 16 O 2 and 12 C 16 O 2 ratio measurements aimed at very low uncertainty. (Notably, creating such an optical instrument and developing technical solutions is beyond the scope of this paper.) The total combined uncertainty will also include the uncertainty component(s) related to the accuracy of calibration on the VPDB-CO 2 δ 13 C scale. Addressing high-accuracy calibrations is presently not straightforward - absolute numerical values of 13 C/ 12 C for the VPDB-CO 2 scale are not well known. Traditional stable isotope mass-spectrometry uses calibrations vs CO 2 evolved from the primary carbonate reference materials; which can hardly be used for calibrating commercial optical stable isotope analysers. In contrast to mass-spectrometry, the major advantage of the laser-based spectrometric technique detailed in this paper is its high robustness. Therefore one can introduce a new spectrometric δ 13 C characterisation method which, being once well-calibrated on the VPDB-CO 2 scale, may not require any further (re-)calibrations. This can be used for characterisation of δ 13 C in CO 2 -in-air mixtures with high precision and also with high accuracy. If this technique can be realised with the estimated long-term reproducibility (order of 10 -6 ), it could potentially serve as a more convenient Optical Transfer Standard (OTS), characterising large amounts of CO 2 gas mixtures on the VPDB-CO 2 δ 13 C scale without having to compare to carbonate-evolved CO 2 . Furthermore, if the OTS method proves to be successful, it might be considered for re-defining the VPDB-CO 2 δ 13 C-scale as the ratio of selected CO 2 spectroscopic absorbance lines measured at pre-defined T & P conditions. The approach can also be expanded to δ 18 O characterisation (using 16 O 12 C 18 O and 16 O 12 C 16 O absorbance lines) of CO 2 gas mixtures and potentially to other isotope ratios of other gases. Copyright © 2018 Elsevier B.V. All rights reserved.

Recent Surface Reflectance Measurement Campaigns with Emphasis on Best Practices, SI Traceability and Uncertainty Estimation

NASA Technical Reports Server (NTRS)

Helder, Dennis; Thome, Kurtis John; Aaron, Dave; Leigh, Larry; Czapla-Myers, Jeff; Leisso, Nathan; Biggar, Stuart; Anderson, Nik

2012-01-01

A significant problem facing the optical satellite calibration community is limited knowledge of the uncertainties associated with fundamental measurements, such as surface reflectance, used to derive satellite radiometric calibration estimates. In addition, it is difficult to compare the capabilities of calibration teams around the globe, which leads to differences in the estimated calibration of optical satellite sensors. This paper reports on two recent field campaigns that were designed to isolate common uncertainties within and across calibration groups, particularly with respect to ground-based surface reflectance measurements. Initial results from these efforts suggest the uncertainties can be as low as 1.5% to 2.5%. In addition, methods for improving the cross-comparison of calibration teams are suggested that can potentially reduce the differences in the calibration estimates of optical satellite sensors.

Optical Model and Cross Section Uncertainties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herman,M.W.; Pigni, M.T.; Dietrich, F.S.

2009-10-05

Distinct minima and maxima in the neutron total cross section uncertainties were observed in model calculations using spherical optical potential. We found this oscillating structure to be a general feature of quantum mechanical wave scattering. Specifically, we analyzed neutron interaction with 56Fe from 1 keV up to 65 MeV, and investigated physical origin of the minima.We discuss their potential importance for practical applications as well as the implications for the uncertainties in total and absorption cross sections.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carvalho, N. C., E-mail: natalia.docarmocarvalho@research.uwa.edu.au; Le Floch, J-M.; Tobar, M. E.

The Y{sub 2}SiO{sub 5} (YSO) crystal is a dielectric material with biaxial anisotropy with known values of refractive index at optical frequencies. It is a well-known rare-earth (RE) host material for optical research and more recently has shown promising performance for quantum-engineered devices. In this paper, we report the first microwave characterization of the real permittivity tensor of a bulk YSO sample, as well as an investigation of the temperature dependence of the tensor components from 296 K down to 6 K. Estimated uncertainties were below 0.26%, limited by the precision of machining the cylindrical dielectric. Also, the electrical Q-factors of amore » few electromagnetic modes were recorded as a way to provide some information about the crystal losses over the temperature range. To solve the tensor components necessary for a biaxial crystal, we developed the multi-mode technique, which uses simultaneous measurement of low order whispering gallery modes. Knowledge of the permittivity tensor offers important data, essential for the design of technologies involving YSO, such as microwave coupling to electron and hyperfine transitions in RE doped samples at low temperatures.« less

Uncertainties of simulated aerosol optical properties induced by assumptions on aerosol physical and chemical properties: an AQMEII-2 perspective

EPA Science Inventory

The calculation of aerosol optical properties from aerosol mass is a process subject to uncertainty related to necessary assumptions on the treatment of the chemical species mixing state, density, refractive index, and hygroscopic growth. In the framework of the AQMEII-2 model in...

Transportable Optical Lattice Clock with 7×10^{-17} Uncertainty.

PubMed

Koller, S B; Grotti, J; Vogt, St; Al-Masoudi, A; Dörscher, S; Häfner, S; Sterr, U; Lisdat, Ch

2017-02-17

We present a transportable optical clock (TOC) with ^{87}Sr. Its complete characterization against a stationary lattice clock resulted in a systematic uncertainty of 7.4×10^{-17}, which is currently limited by the statistics of the determination of the residual lattice light shift, and an instability of 1.3×10^{-15}/sqrt[τ] with an averaging time τ in seconds. Measurements confirm that the systematic uncertainty can be reduced to below the design goal of 1×10^{-17}. To our knowledge, these are the best uncertainties and instabilities reported for any transportable clock to date. For autonomous operation, the TOC has been installed in an air-conditioned car trailer. It is suitable for chronometric leveling with submeter resolution as well as for intercontinental cross-linking of optical clocks, which is essential for a redefinition of the International System of Units (SI) second. In addition, the TOC will be used for high precision experiments for fundamental science that are commonly tied to precise frequency measurements and its development is an important step to space-borne optical clocks.

Transportable Optical Lattice Clock with 7 ×10-17 Uncertainty

NASA Astrophysics Data System (ADS)

Koller, S. B.; Grotti, J.; Vogt, St.; Al-Masoudi, A.; Dörscher, S.; Häfner, S.; Sterr, U.; Lisdat, Ch.

2017-02-01

We present a transportable optical clock (TOC) with Sr 87 . Its complete characterization against a stationary lattice clock resulted in a systematic uncertainty of 7.4 ×10-17, which is currently limited by the statistics of the determination of the residual lattice light shift, and an instability of 1.3 ×10-15/√{τ } with an averaging time τ in seconds. Measurements confirm that the systematic uncertainty can be reduced to below the design goal of 1 ×10-17. To our knowledge, these are the best uncertainties and instabilities reported for any transportable clock to date. For autonomous operation, the TOC has been installed in an air-conditioned car trailer. It is suitable for chronometric leveling with submeter resolution as well as for intercontinental cross-linking of optical clocks, which is essential for a redefinition of the International System of Units (SI) second. In addition, the TOC will be used for high precision experiments for fundamental science that are commonly tied to precise frequency measurements and its development is an important step to space-borne optical clocks.

Bi-Directional Brillouin Optical Time Domain Analyzer System for Long Range Distributed Sensing.

PubMed

Guo, Nan; Wang, Liang; Wang, Jie; Jin, Chao; Tam, Hwa-Yaw; Zhang, A Ping; Lu, Chao

2016-12-16

We propose and experimentally demonstrate a novel scheme of bi-directional Brillouin time domain analyzer (BD-BOTDA) to extend the sensing range. By deploying two pump-probe pairs at two different wavelengths, the Brillouin frequency shift (BFS) distribution over each half of the whole fiber can be obtained with the simultaneous detection of Brillouin signals in both channels. Compared to the conventional unidirectional BOTDA system of the same sensing range, the proposed BD-BOTDA scheme enables distributed sensing with a performance level comparable to the conventional one with half of the sensing range and a spatial resolution of 2 m, while maintaining the Brillouin signal-to-noise ratio (SNR) and the BFS uncertainty. Based on this technique, we have achieved distributed temperature sensing with a measurement range of 81.9 km fiber at a spatial resolution of 2 m and BFS uncertainty of ~0.44 MHz without introducing any complicated components or schemes.

Measurement-based climatology of aerosol direct radiative effect, its sensitivities, and uncertainties from a background southeast US site

NASA Astrophysics Data System (ADS)

Sherman, James P.; McComiskey, Allison

2018-03-01

Aerosol optical properties measured at Appalachian State University's co-located NASA AERONET and NOAA ESRL aerosol network monitoring sites over a nearly four-year period (June 2012-Feb 2016) are used, along with satellite-based surface reflectance measurements, to study the seasonal variability of diurnally averaged clear sky aerosol direct radiative effect (DRE) and radiative efficiency (RE) at the top-of-atmosphere (TOA) and at the surface. Aerosol chemistry and loading at the Appalachian State site are likely representative of the background southeast US (SE US), home to high summertime aerosol loading and one of only a few regions not to have warmed during the 20th century. This study is the first multi-year ground truth DRE study in the SE US, using aerosol network data products that are often used to validate satellite-based aerosol retrievals. The study is also the first in the SE US to quantify DRE uncertainties and sensitivities to aerosol optical properties and surface reflectance, including their seasonal dependence.Median DRE for the study period is -2.9 W m-2 at the TOA and -6.1 W m-2 at the surface. Monthly median and monthly mean DRE at the TOA (surface) are -1 to -2 W m-2 (-2 to -3 W m-2) during winter months and -5 to -6 W m-2 (-10 W m-2) during summer months. The DRE cycles follow the annual cycle of aerosol optical depth (AOD), which is 9 to 10 times larger in summer than in winter. Aerosol RE is anti-correlated with DRE, with winter values 1.5 to 2 times more negative than summer values. Due to the large seasonal dependence of aerosol DRE and RE, we quantify the sensitivity of DRE to aerosol optical properties and surface reflectance, using a calendar day representative of each season (21 December for winter; 21 March for spring, 21 June for summer, and 21 September for fall). We use these sensitivities along with measurement uncertainties of aerosol optical properties and surface reflectance to calculate DRE uncertainties. We also estimate uncertainty in calculated diurnally-averaged DRE due to diurnal aerosol variability. Aerosol DRE at both the TOA and surface is most sensitive to changes in AOD, followed by single-scattering albedo (ω0). One exception is under the high summertime aerosol loading conditions (AOD ≥ 0.15 at 550 nm), when sensitivity of TOA DRE to ω0 is comparable to that of AOD. Aerosol DRE is less sensitive to changes in scattering asymmetry parameter (g) and surface reflectance (R). While DRE sensitivity to AOD varies by only ˜ 25 to 30 % with season, DRE sensitivity to ω0, g, and R largely follow the annual AOD cycle at APP, varying by factors of 8 to 15 with season. Since the measurement uncertainties of AOD, ω0, g, and R are comparable at Appalachian State, their relative contributions to DRE uncertainty are largely influenced by their (seasonally dependent) DRE sensitivity values, which suggests that the seasonal dependence of DRE uncertainty must be accounted for. Clear sky aerosol DRE uncertainty at the TOA (surface) due to measurement uncertainties ranges from 0.45 (0.75 W m-2) for December to 1.1 (1.6 W m-2) for June. Expressed as a fraction of DRE computed using monthly median aerosol optical properties and surface reflectance, the DRE uncertainties at TOA (surface) are 20 to 24 % (15 to 22 %) for March, June, and September and 49 (50 %) for DEC. The relatively low DRE uncertainties are largely due to the low uncertainty in AOD measured by AERONET. Use of satellite-based AOD measurements by MODIS in the DRE calculations increases DRE uncertainties by a factor of 2 to 5 and DRE uncertainties are dominated by AOD uncertainty for all seasons. Diurnal variability in AOD (and to a lesser extent g) contributes to uncertainties in DRE calculated using daily-averaged aerosol optical properties that are slightly larger (by ˜ 20 to 30 %) than DRE uncertainties due to measurement uncertainties during summer and fall, with comparable uncertainties during winter and spring.

Temporal variability in SeaWiFS derived apparent optical properties in European seas

NASA Astrophysics Data System (ADS)

Vantrepotte, V.; Mélin, F.

2010-02-01

The 10-year record of ocean color data provided by the SeaWiFS mission is an important asset for monitoring and research activities conducted on the optically complex European seas. This study makes use of the SeaWiFS data set of normalized water leaving radiances LWN to study the major characteristics of temporal variability associated with optical properties across the entire European domain. Specifically, the time series of LWN and associated band ratios are decomposed into terms representing a fixed seasonal cycle, irregular variations and trends, and the contribution of these components to the total variance is described for the various basins. The diversity of the European waters is fully reflected by the range of results varying with regions and wavelengths. Generally, the Mediterranean and Baltic seas appear as two end-members with, respectively, high and low contributions of the seasonal component to the total variance. The existence of linear trends affecting the satellite products is also explored for each basin. By focusing the analysis on LWN and band ratios, the validity of the results is not limited by the varying levels of uncertainty that characterize derived products such as the concentration of chlorophyll a in optically complex waters. Statistically significant, and in some cases large, trends are detected in the Atlantic Ocean west of the European western shelf, the central North Sea, the English Channel, the Black Sea, the northern Adriatic, and various regions of the Mediterranean Sea and the northern Baltic Sea, revealing changes in the concentrations of optically significant constituents in these regions.

Integrated Modeling Activities for the James Webb Space Telescope (JWST): Structural-Thermal-Optical Analysis

NASA Technical Reports Server (NTRS)

Johnston, John D.; Parrish, Keith; Howard, Joseph M.; Mosier, Gary E.; McGinnis, Mark; Bluth, Marcel; Kim, Kevin; Ha, Hong Q.

2004-01-01

This is a continuation of a series of papers on modeling activities for JWST. The structural-thermal- optical, often referred to as "STOP", analysis process is used to predict the effect of thermal distortion on optical performance. The benchmark STOP analysis for JWST assesses the effect of an observatory slew on wavefront error. The paper begins an overview of multi-disciplinary engineering analysis, or integrated modeling, which is a critical element of the JWST mission. The STOP analysis process is then described. This process consists of the following steps: thermal analysis, structural analysis, and optical analysis. Temperatures predicted using geometric and thermal math models are mapped to the structural finite element model in order to predict thermally-induced deformations. Motions and deformations at optical surfaces are input to optical models and optical performance is predicted using either an optical ray trace or WFE estimation techniques based on prior ray traces or first order optics. Following the discussion of the analysis process, results based on models representing the design at the time of the System Requirements Review. In addition to baseline performance predictions, sensitivity studies are performed to assess modeling uncertainties. Of particular interest is the sensitivity of optical performance to uncertainties in temperature predictions and variations in metal properties. The paper concludes with a discussion of modeling uncertainty as it pertains to STOP analysis.

Measuring the photodetector frequency response for ultrasonic applications by a heterodyne system with difference- frequency servo control.

PubMed

Koch, Christian

2010-05-01

A technique for the calibration of photodiodes in ultrasonic measurement systems using standard and cost-effective optical and electronic components is presented. A heterodyne system was realized using two commercially available distributed feedback lasers, and the required frequency stability and resolution were ensured by a difference-frequency servo control scheme. The frequency-sensitive element generating the error signal for the servo loop comprised a delay-line discriminator constructed from electronic elements. Measurements were carried out at up to 450 MHz, and the uncertainties of about 5% (k = 2) can be further reduced by improved radio frequency power measurement without losing the feature of using only simple elements. The technique initially dedicated to the determination of the frequency response of photodetectors applied in ultrasonic applications can be transferred to other application fields of optical measurements.

Quantum issues in optical communication. [noise reduction in signal reception

NASA Technical Reports Server (NTRS)

Kennedy, R. S.

1973-01-01

Various approaches to the problem of controlling quantum noise, the dominant noise in an optical communications system, are discussed. It is shown that, no matter which way the problem is approached, there always remain uncertainties. These uncertainties exist because, to date, only very few communication problems have been solved in their full quantum form.

Defining the uncertainty of electro-optical identification system performance estimates using a 3D optical environment derived from satellite

NASA Astrophysics Data System (ADS)

Ladner, S. D.; Arnone, R.; Casey, B.; Weidemann, A.; Gray, D.; Shulman, I.; Mahoney, K.; Giddings, T.; Shirron, J.

2009-05-01

Current United States Navy Mine-Counter-Measure (MCM) operations primarily use electro-optical identification (EOID) sensors to identify underwater targets after detection via acoustic sensors. These EOID sensors which are based on laser underwater imaging by design work best in "clear" waters and are limited in coastal waters especially with strong optical layers. Optical properties and in particular scattering and absorption play an important role on systems performance. Surface optical properties alone from satellite are not adequate to determine how well a system will perform at depth due to the existence of optical layers. The spatial and temporal characteristics of the 3d optical variability of the coastal waters along with strength and location of subsurface optical layers maximize chances of identifying underwater targets by exploiting optimum sensor deployment. Advanced methods have been developed to fuse the optical measurements from gliders, optical properties from "surface" satellite snapshot and 3-D ocean circulation models to extend the two-dimensional (2-D) surface satellite optical image into a three-dimensional (3-D) optical volume with subsurface optical layers. Modifications were made to an EOID performance model to integrate a 3-D optical volume covering an entire region of interest as input and derive system performance field. These enhancements extend present capability based on glider optics and EOID sensor models to estimate the system's "image quality". This only yields system performance information for a single glider profile location in a very large operational region. Finally, we define the uncertainty of the system performance by coupling the EOID performance model with the 3-D optical volume uncertainties. Knowing the ensemble spread of EOID performance field provides a new and unique capability for tactical decision makers and Navy Operations.

Synthesis and Control of Flexible Systems with Component-Level Uncertainties

NASA Technical Reports Server (NTRS)

Maghami, Peiman G.; Lim, Kyong B.

2009-01-01

An efficient and computationally robust method for synthesis of component dynamics is developed. The method defines the interface forces/moments as feasible vectors in transformed coordinates to ensure that connectivity requirements of the combined structure are met. The synthesized system is then defined in a transformed set of feasible coordinates. The simplicity of form is exploited to effectively deal with modeling parametric and non-parametric uncertainties at the substructure level. Uncertainty models of reasonable size and complexity are synthesized for the combined structure from those in the substructure models. In particular, we address frequency and damping uncertainties at the component level. The approach first considers the robustness of synthesized flexible systems. It is then extended to deal with non-synthesized dynamic models with component-level uncertainties by projecting uncertainties to the system level. A numerical example is given to demonstrate the feasibility of the proposed approach.

A multi-spectral approach to simultaneously retrieve above-cloud smoke optical depth and the optical and microphysical properties of underlying marine stratocumulus clouds using MODIS

NASA Astrophysics Data System (ADS)

Meyer, K.; Platnick, S. E.; Zhang, Z.

2013-12-01

Clouds, aerosols, and their interactions are widely considered to be key uncertainty components in our current understanding of the Earth's atmosphere and radiation budget. The work presented here is focused on the quasi-permanent marine boundary layer (MBL) clouds over the southeastern Atlantic Ocean, which underlie a near-persistent smoke layer produced from extensive biomass burning throughout the southern African savanna during austral winter. The absorption of the above-cloud smoke layer, which increases with decreasing wavelength, can introduce biases into the standard MODIS cloud optical and microphysical property retrievals of the underlying MBL clouds. This effect is more pronounced in the cloud optical thickness retrievals, which over ocean are derived from the wavelength channel centered near 0.86 μm (effective particle size retrievals are derived from the short and mid-wave IR channels at 1.6, 2.1, and 3.7 μm). Here, a new method is introduced to simultaneously retrieve the above-cloud smoke aerosol optical depth (AOD) and the unbiased cloud optical thickness (COT) and effective radius (CER) using multiple MODIS spectral channels in the visible and near- and shortwave-infrared. Preliminary retrieval results are shown, as are comparisons with other A-Train sensors.

An imager-based multispectral retrieval of above-cloud absorbing aerosol optical depth and the optical and microphysical properties of underlying marine stratocumulus clouds

NASA Astrophysics Data System (ADS)

Meyer, K.; Platnick, S. E.; Zhang, Z.

2014-12-01

Clouds, aerosols, and their interactions are widely considered to be key uncertainty components in our current understanding of the Earth's atmosphere and radiation budget. The work presented here is focused on the quasi-permanent marine boundary layer (MBL) clouds over the southeastern Atlantic Ocean, which underlie a near-persistent smoke layer produced from extensive biomass burning throughout the southern African savanna during austral winter. The absorption of the above-cloud smoke layer, which increases with decreasing wavelength, can introduce biases into imager-based cloud optical and microphysical property retrievals of the underlying MBL clouds. This effect is more pronounced for cloud optical thickness retrievals, which are typically derived from the visible or near-IR wavelength channels (effective particle size retrievals are derived from short and mid-wave IR channels that are less affected by aerosol absorption). Here, a new method is introduced to simultaneously retrieve the above-cloud smoke aerosol optical depth (AOD) and the unbiased cloud optical thickness (COT) and effective radius (CER) using multiple spectral channels in the visible and near- and shortwave-IR. The technique has been applied to MODIS, and retrieval results and statistics, as well as comparisons with other A-Train sensors, are shown.

Cosmic ray energy spectrum measurement with the Antarctic Muon and Neutrino Detector Array (AMANDA)

NASA Astrophysics Data System (ADS)

Chirkin, Dmitry Aleksandrovich

AMANDA-II is a neutrino telescope composed of 677 optical sensors organized along 19 strings buried deep in the Antarctic ice cap. It is designed to detect Cherenkov light produced by cosmic-ray- and neutrino-induced charged leptons. The majority of events recorded by AMANDA-II are caused by muons which are produced in the atmosphere by high-energy cosmic rays. The leading uncertainties in simulating such events come from the choice of the high-energy model used to describe the first interaction of the cosmic rays, uncertainties in our knowledge and implementation of the ice properties at the depth of the detector, and individual optical module sensitivities. Contributions from uncertainties in the atmospheric conditions and muon cross sections in ice are smaller. The downgoing muon simulation was substantially improved by using the extensive air shower generator CORSIKA to describe the shower development in the atmosphere, and by writing a new software package for the muon propagation (MMC), which reduced computational and algorithm errors below the level of uncertainties of the muon cross sections in ice. A method was developed that resulted in a flux measurement of cosmic rays with energies 1.5--200 TeV per nucleon (95% of primaries causing low-multiplicity events in AMANDA-II have energies in this range) independent of ice model and optical module sensitivities. Predictions of six commonly used high-energy interaction models (QGSJET, VENUS, NEXUS, DPMJET, HDPM, and SIBYLL) are compared to data. The best agreement with direct measurements is achieved with QGSJET, VENUS, and NEXUS. Assuming a power-law energy spectrum (phi0,i · E -gammai) for cosmic-ray components from hydrogen to iron (i = H,..., Fe) and their mass distribution according to Wiebel-South (Wiebel-South & Biermann, 1999), phi 0,i and gammai were corrected to achieve the best description of the data. For the hydrogen component, values of phi0,H = 0.106 +/- 0.007 m-2 sr-1s-1TeV-1 , gammaH = 2.70 +/- 0.02 are obtained. For the South Pole, a vertical muon flux at 1 TeV of (1.05 +/- 0.07) · 10 -10 cm-2 sr-1s -1GeV-1 is obtained (for all interaction models), and the fitted spectral index is 2.66 +/- 0.02 (for QGSJET, VENUS, and NEXUS). The difference in the predicted value of the spectral index gamma between high-energy interaction models is as much as 0.1, which is explained by the difference in the observed muon multiplicity at the depth of the detector in data simulated with different interaction models.

FIBER OPTICS: Schrödinger soliton in a fiber waveguide exhibiting both gain and losses: squeezed states and growth of noise in the linear approximation

NASA Astrophysics Data System (ADS)

Belinskiĭ, A. V.

1992-09-01

An investigation is made of the evolution of quantum fluctuations of a fundamental soliton in the course of its propagation in a nonlinear fiber waveguide characterized by losses and compensated by amplification. Simple relationships are obtained for the amplitude and phase noise, quantum uncertainty of the position and momentum, and also fluctuations of the quadrature components of the radiation field. Numerical estimates are obtained. It is shown that loss-compensating amplification is unnecessary for efficient formation of squeezed states of a soliton.

Multimode squeezing, biphotons and uncertainty relations in polarization quantum optics

NASA Technical Reports Server (NTRS)

Karassiov, V. P.

1994-01-01

The concept of squeezing and uncertainty relations are discussed for multimode quantum light with the consideration of polarization. Using the polarization gauge SU(2) invariance of free electromagnetic fields, we separate the polarization and biphoton degrees of freedom from other ones, and consider uncertainty relations characterizing polarization and biphoton observables. As a consequence, we obtain a new classification of states of unpolarized (and partially polarized) light within quantum optics. We also discuss briefly some interrelations of our analysis with experiments connected with solving some fundamental problems of physics.

Flowing-water optical power meter for primary-standard, multi-kilowatt laser power measurements

NASA Astrophysics Data System (ADS)

Williams, P. A.; Hadler, J. A.; Cromer, C.; West, J.; Li, X.; Lehman, J. H.

2018-06-01

A primary-standard flowing-water optical power meter for measuring multi-kilowatt laser emission has been built and operated. The design and operational details of this primary standard are described, and a full uncertainty analysis is provided covering the measurement range from 1–10 kW with an expanded uncertainty of 1.2%. Validating measurements at 5 kW and 10 kW show agreement with other measurement techniques to within the measurement uncertainty. This work of the U.S. Government is not subject to U.S. copyright.

Inverse kinematic problem for a random gradient medium in geometric optics approximation

NASA Astrophysics Data System (ADS)

Petersen, N. V.

1990-03-01

Scattering at random inhomogeneities in a gradient medium results in systematic deviations of the rays and travel times of refracted body waves from those corresponding to the deterministic velocity component. The character of the difference depends on the parameters of the deterministic and random velocity component. However, at great distances to the source, independently of the velocity parameters (weakly or strongly inhomogeneous medium), the most probable depth of the ray turning point is smaller than that corresponding to the deterministic velocity component, the most probable travel times also being lower. The relative uncertainty in the deterministic velocity component, derived from the mean travel times using methods developed for laterally homogeneous media (for instance, the Herglotz-Wiechert method), is systematic in character, but does not exceed the contrast of velocity inhomogeneities by magnitude. The gradient of the deterministic velocity component has a significant effect on the travel-time fluctuations. The variance at great distances to the source is mainly controlled by shallow inhomogeneities. The travel-time flucutations are studied only for weakly inhomogeneous media.

Current Research In The Institut D'optique - Orsay

NASA Astrophysics Data System (ADS)

Marechal, A.

1985-01-01

I - FUNDAMENTAL PROBLEMS A. ASPECT : Non locality in wave mechanics. The Einstein-Bohr dispute and the optical test of Bell's inequalities. A. Einstein and N. Bohr had a discussion about the role of probabilities in microphysics; as is well known the location and momentum of particles cannot be known precisely but only through probabilistic expressions. Einstein thought that complementary variables (hidden variables) are unknown at the present time and that the knowledge of those variables would suppress the actual uncertainty "God does not play random games". On the contrary, Bohr advocated the fundamental role of probabilities. During the sixties J. Bell established inequalities supporting the Einstein point of view. These inequalities are in contradiction with the predictions of quantum mechanics in some very rare situations. A.Aspect designed and realised an optical experiment where the correlation of polarisation of photons emitted by a single atom was measured with a very good signal to noise ratio. Moreover the orientation of the polarisation analyser was changed during the time of flight of photons. The experimental result is in full agreement with the point of view of N. Bohr : the uncertainty on the movement of particles is a fundamental component of the laws of nature and Bell's inequalities do not hold.

Quantification of uncertainty in aerosol optical thickness retrieval arising from aerosol microphysical model and other sources, applied to Ozone Monitoring Instrument (OMI) measurements

NASA Astrophysics Data System (ADS)

Määttä, A.; Laine, M.; Tamminen, J.; Veefkind, J. P.

2014-05-01

Satellite instruments are nowadays successfully utilised for measuring atmospheric aerosol in many applications as well as in research. Therefore, there is a growing need for rigorous error characterisation of the measurements. Here, we introduce a methodology for quantifying the uncertainty in the retrieval of aerosol optical thickness (AOT). In particular, we concentrate on two aspects: uncertainty due to aerosol microphysical model selection and uncertainty due to imperfect forward modelling. We apply the introduced methodology for aerosol optical thickness retrieval of the Ozone Monitoring Instrument (OMI) on board NASA's Earth Observing System (EOS) Aura satellite, launched in 2004. We apply statistical methodologies that improve the uncertainty estimates of the aerosol optical thickness retrieval by propagating aerosol microphysical model selection and forward model error more realistically. For the microphysical model selection problem, we utilise Bayesian model selection and model averaging methods. Gaussian processes are utilised to characterise the smooth systematic discrepancies between the measured and modelled reflectances (i.e. residuals). The spectral correlation is composed empirically by exploring a set of residuals. The operational OMI multi-wavelength aerosol retrieval algorithm OMAERO is used for cloud-free, over-land pixels of the OMI instrument with the additional Bayesian model selection and model discrepancy techniques introduced here. The method and improved uncertainty characterisation is demonstrated by several examples with different aerosol properties: weakly absorbing aerosols, forest fires over Greece and Russia, and Sahara desert dust. The statistical methodology presented is general; it is not restricted to this particular satellite retrieval application.

Proposed standardized definitions for vertical resolution and uncertainty in the NDACC lidar ozone and temperature algorithms - Part 3: Temperature uncertainty budget

NASA Astrophysics Data System (ADS)

Leblanc, Thierry; Sica, Robert J.; van Gijsel, Joanna A. E.; Haefele, Alexander; Payen, Guillaume; Liberti, Gianluigi

2016-08-01

A standardized approach for the definition, propagation, and reporting of uncertainty in the temperature lidar data products contributing to the Network for the Detection for Atmospheric Composition Change (NDACC) database is proposed. One important aspect of the proposed approach is the ability to propagate all independent uncertainty components in parallel through the data processing chain. The individual uncertainty components are then combined together at the very last stage of processing to form the temperature combined standard uncertainty. The identified uncertainty sources comprise major components such as signal detection, saturation correction, background noise extraction, temperature tie-on at the top of the profile, and absorption by ozone if working in the visible spectrum, as well as other components such as molecular extinction, the acceleration of gravity, and the molecular mass of air, whose magnitudes depend on the instrument, data processing algorithm, and altitude range of interest. The expression of the individual uncertainty components and their step-by-step propagation through the temperature data processing chain are thoroughly estimated, taking into account the effect of vertical filtering and the merging of multiple channels. All sources of uncertainty except detection noise imply correlated terms in the vertical dimension, which means that covariance terms must be taken into account when vertical filtering is applied and when temperature is integrated from the top of the profile. Quantitatively, the uncertainty budget is presented in a generic form (i.e., as a function of instrument performance and wavelength), so that any NDACC temperature lidar investigator can easily estimate the expected impact of individual uncertainty components in the case of their own instrument. Using this standardized approach, an example of uncertainty budget is provided for the Jet Propulsion Laboratory (JPL) lidar at Mauna Loa Observatory, Hawai'i, which is typical of the NDACC temperature lidars transmitting at 355 nm. The combined temperature uncertainty ranges between 0.1 and 1 K below 60 km, with detection noise, saturation correction, and molecular extinction correction being the three dominant sources of uncertainty. Above 60 km and up to 10 km below the top of the profile, the total uncertainty increases exponentially from 1 to 10 K due to the combined effect of random noise and temperature tie-on. In the top 10 km of the profile, the accuracy of the profile mainly depends on that of the tie-on temperature. All other uncertainty components remain below 0.1 K throughout the entire profile (15-90 km), except the background noise correction uncertainty, which peaks around 0.3-0.5 K. It should be kept in mind that these quantitative estimates may be very different for other lidar instruments, depending on their altitude range and the wavelengths used.

Useful optical density range in film dosimetry: limitations due to noise and saturation.

PubMed

González-López, Antonio

2007-08-07

The optical density (OD) range for the scanners used in film dosimetry is limited due to saturation and noise. As the OD increases, saturation causes the rate of change of the output with respect to the input to become smaller, while at the same time noise remains fairly constant or increases. The combined effect leads to a degradation of the signal-to-noise ratio (SNR) at high optical densities. In this study, the uncertainty in the OD measurement, d(m), is expressed as a function of the optical density d. The functional relationship obtained gives the amplitude w of an interval around d in which d(m) will be found with a given probability p. The relationship w = w(d, p) is later used to determine which OD ranges fulfil a set of requirements on w and p. As an application of the procedure, the noise and saturation characteristics of a commercial film digitizer system are measured. Their contribution to the uncertainties of the dosimetric procedure is reported, and the data are used to provide an optical density range for a given uncertainty and confidence level associated with the digitizer. These data can be further combined with the data from other sources of noise such as film noise in order to estimate the final uncertainty of the dosimetric process.

Modified thermal-optical analysis using spectral absorption selectivity to distinguish black carbon from pyrolized organic carbon.

PubMed

Hadley, Odelle L; Corrigan, Craig E; Kirchstetter, Thomas W

2008-11-15

This study presents a method for analyzing the black carbon (BC) mass loading on a quartz fiber filter using a modified thermal-optical analysis method, wherein light transmitted through the sample is measured over a spectral region instead of at a single wavelength. Evolution of the spectral light transmission signal depends on the relative amounts of light-absorbing BC and char, the latter of which forms when organic carbon in the sample pyrolyzes during heating. Absorption selectivities of BC and char are found to be distinct and are used to apportion the amount of light attenuated by each component in the sample. Light attenuation is converted to mass concentration on the basis of derived mass attenuation efficiencies (MAEs) of BC and char. The fractions of attenuation due to each component are scaled by their individual MAE values and added together as the total mass of light absorbing carbon (LAC). An iterative algorithm is used to find the MAE values for both BC and char that provide the best fit to the carbon mass remaining on the filter (derived from direct measurements of thermally evolved CO2) at temperatures higher than 480 degrees C. This method was applied to measure the BC concentration in precipitation samples collected in northern California. The uncertainty in the measured BC concentration of samples that contained a high concentration of organics susceptible to char ranged from 12% to 100%, depending on the mass loading of BC on the filter. The lower detection limit for this method was approximately 0.35 microg of BC, and the uncertainty approached 20% for BC mass loading greater than 1.0 microg of BC.

Improved entrance optic for global irradiance measurements with a Brewer spectrophotometer.

PubMed

Gröbner, Julian

2003-06-20

A new entrance optic for a Brewer spectrophotometer has been designed and tested both in the laboratory and during solar measurements. The integrated cosine response deviates by 2.4% from the ideal, with an uncertainty of +/- 1%. The systematic uncertainties of global solar irradiance measurements with this new entrance optic are considerably reduced compared with measurements with the traditional design. Simultaneous solar irradiance measurements between the Brewer spectrophotometer and a spectroradiometer equipped with a state-of-the-art shaped diffuser agreed to within +/- 2% during a five-day measurement period.

Bayesian assessment of uncertainty in aerosol size distributions and index of refraction retrieved from multiwavelength lidar measurements.

PubMed

Herman, Benjamin R; Gross, Barry; Moshary, Fred; Ahmed, Samir

2008-04-01

We investigate the assessment of uncertainty in the inference of aerosol size distributions from backscatter and extinction measurements that can be obtained from a modern elastic/Raman lidar system with a Nd:YAG laser transmitter. To calculate the uncertainty, an analytic formula for the correlated probability density function (PDF) describing the error for an optical coefficient ratio is derived based on a normally distributed fractional error in the optical coefficients. Assuming a monomodal lognormal particle size distribution of spherical, homogeneous particles with a known index of refraction, we compare the assessment of uncertainty using a more conventional forward Monte Carlo method with that obtained from a Bayesian posterior PDF assuming a uniform prior PDF and show that substantial differences between the two methods exist. In addition, we use the posterior PDF formalism, which was extended to include an unknown refractive index, to find credible sets for a variety of optical measurement scenarios. We find the uncertainty is greatly reduced with the addition of suitable extinction measurements in contrast to the inclusion of extra backscatter coefficients, which we show to have a minimal effect and strengthens similar observations based on numerical regularization methods.

Visible and infrared optical properties of stacked cone graphite microtubes.

PubMed

Bruce, Charles W; Alyones, Sharhabeel

2012-06-01

The absorptive and scattering optical properties of heat-treated, vapor-grown, graphite microtubes consisting of nanotubes in a "stacked cone" configuration were investigated through the visible and infrared wavelengths using photoacoustic and other spectrometric techniques. However, computations of these properties involved uncertainties that were not easily resolved; the appropriate dielectric coefficients were presumed to be a combination of the published values for the distinct orientations of graphite, but the correct proportions are not evident and none of the reasonable choices produced satisfactory agreement (within the measurement limits of error). Since both of the primary components of the extinction were measured, the appropriate computational codes were employed in reverse to compute the dielectric coefficients for the graphite microtubes. Differences, primarily for the imaginary index, are most distinct for visible and near infrared wavelengths; in this wavelength region, the imaginary index falls progressively to less than half that for the computed mixture.

A model-averaging method for assessing groundwater conceptual model uncertainty.

PubMed

Ye, Ming; Pohlmann, Karl F; Chapman, Jenny B; Pohll, Greg M; Reeves, Donald M

2010-01-01

This study evaluates alternative groundwater models with different recharge and geologic components at the northern Yucca Flat area of the Death Valley Regional Flow System (DVRFS), USA. Recharge over the DVRFS has been estimated using five methods, and five geological interpretations are available at the northern Yucca Flat area. Combining the recharge and geological components together with additional modeling components that represent other hydrogeological conditions yields a total of 25 groundwater flow models. As all the models are plausible given available data and information, evaluating model uncertainty becomes inevitable. On the other hand, hydraulic parameters (e.g., hydraulic conductivity) are uncertain in each model, giving rise to parametric uncertainty. Propagation of the uncertainty in the models and model parameters through groundwater modeling causes predictive uncertainty in model predictions (e.g., hydraulic head and flow). Parametric uncertainty within each model is assessed using Monte Carlo simulation, and model uncertainty is evaluated using the model averaging method. Two model-averaging techniques (on the basis of information criteria and GLUE) are discussed. This study shows that contribution of model uncertainty to predictive uncertainty is significantly larger than that of parametric uncertainty. For the recharge and geological components, uncertainty in the geological interpretations has more significant effect on model predictions than uncertainty in the recharge estimates. In addition, weighted residuals vary more for the different geological models than for different recharge models. Most of the calibrated observations are not important for discriminating between the alternative models, because their weighted residuals vary only slightly from one model to another.

Validation of aerosol optical depth uncertainties within the ESA Climate Change Initiative

NASA Astrophysics Data System (ADS)

Stebel, Kerstin; Povey, Adam; Popp, Thomas; Capelle, Virginie; Clarisse, Lieven; Heckel, Andreas; Kinne, Stefan; Klueser, Lars; Kolmonen, Pekka; de Leeuw, Gerrit; North, Peter R. J.; Pinnock, Simon; Sogacheva, Larisa; Thomas, Gareth; Vandenbussche, Sophie

2017-04-01

Uncertainty is a vital component of any climate data record as it provides the context with which to understand the quality of the data and compare it to other measurements. Therefore, pixel-level uncertainties are provided for all aerosol products that have been developed in the framework of the Aerosol_cci project within ESA's Climate Change Initiative (CCI). Validation of these estimated uncertainties is necessary to demonstrate that they provide a useful representation of the distribution of error. We propose a technique for the statistical validation of AOD (aerosol optical depth) uncertainty by comparison to high-quality ground-based observations and present results for ATSR (Along Track Scanning Radiometer) and IASI (Infrared Atmospheric Sounding Interferometer) data records. AOD at 0.55 µm and its uncertainty was calculated with three AOD retrieval algorithms using data from the ATSR instruments (ATSR-2 (1995-2002) and AATSR (2002-2012)). Pixel-level uncertainties were calculated through error propagation (ADV/ASV, ORAC algorithms) or parameterization of the error's dependence on the geophysical retrieval conditions (SU algorithm). Level 2 data are given as super-pixels of 10 km x 10 km. As validation data, we use direct-sun observations of AOD from the AERONET (AErosol RObotic NETwork) and MAN (Maritime Aerosol Network) sun-photometer networks, which are substantially more accurate than satellite retrievals. Neglecting the uncertainty in AERONET observations and possible issues with their ability to represent a satellite pixel area, the error in the retrieval can be approximated by the difference between the satellite and AERONET retrievals (herein referred to as "error"). To evaluate how well the pixel-level uncertainty represents the observed distribution of error, we look at the distribution of the ratio D between the "error" and the ATSR uncertainty. If uncertainties are well represented, D should be normally distributed and 68.3% of values should fall within the range [-1, +1]. A non-zero mean of D indicates the presence of residual systematic errors. If the fraction is smaller than 68%, uncertainties are underestimated; if it is larger, uncertainties are overestimated. For the three ATSR algorithms, we provide statistics and an evaluation at a global scale (separately for land and ocean/coastal regions), for high/low AOD regimes, and seasonal and regional statistics (e.g. Europe, N-Africa, East-Asia, N-America). We assess the long-term stability of the uncertainty estimates over the 17-year time series, and the consistency between ATSR-2 and AATSR results (during their period of overlap). Furthermore, we exploit the possibility to adapt the uncertainty validation concept to the IASI datasets. Ten-year data records (2007-2016) of dust AOD have been generated with four algorithms using IASI observations over the greater Sahara region [80°W - 120°E, 0°N - 40°N]. For validation, the coarse mode AOD at 0.55 μm from the AERONET direct-sun spectral deconvolution algorithm (SDA) product may be used as a proxy for desert dust. The uncertainty validation results for IASI are still tentative, as larger IASI pixel sizes and the conversion of the IASI AOD values from infrared to visible wavelengths for comparison to ground-based observations introduces large uncertainties.

Optimizations for optical velocity measurements in narrow gaps

NASA Astrophysics Data System (ADS)

Schlüßler, Raimund; Blechschmidt, Christian; Czarske, Jürgen; Fischer, Andreas

2013-09-01

Measuring the flow velocity in small gaps or near a surface with a nonintrusive optical measurement technique is a challenging measurement task, as disturbing light reflections from the surface appear. However, these measurements are important, e.g., in order to understand and to design the leakage flow in the tip gap between the rotor blade end face and the housing of a turbomachine. Hence, methods to reduce the interfering light power and to correct measurement errors caused by it need to be developed and verified. Different alternatives of minimizing the interfering light power for optical flow measurements in small gaps are presented. By optimizing the beam shape of the applied illumination beam using a numerical diffraction simulation, the interfering light power is reduced by up to a factor of 100. In combination with a decrease of the reflection coefficient of the rotor blade surface, an additional reduction of the interfering light power below the used scattered light power is possible. Furthermore, a correction algorithm to decrease the measurement uncertainty of disturbed measurements is derived. These improvements enable optical three-dimensional three-component flow velocity measurements in submillimeter gaps or near a surface.

Low cost ellipsometer using a standard commercial polarimeter

NASA Astrophysics Data System (ADS)

Velosa, F.; Abreu, M.

2017-08-01

Ellipsometry is an optical technique to characterize materials or phenomena that occurs at an interface or thin film between two different media. In this paper, we present an experimental low-cost version of a photometric ellipsometer, assembled with commonly found material at every Optics laboratory. The polarization parameters measurement was performed using a Thorlabs PAX5710 polarimeter. The uncertainty computed using the Guide to the Expression of Uncertainty in Measurement (GUM) procedures. With the assembled ellipsometer we were able to measure the thickness of a 10 nm thick SiO2 thin film deposited upon Si, and the complex refractive index of Gold and Tantalum samples. The SiO2 thickness we achieved had an experimental deviation of 4.5% with 2.00 nm uncertainty. The value complex refractive index of Gold and Tantalum measured agrees with the different values found in several references. The uncertainty values were found to be mostly limited by the polarimeter's uncertainty.

Measurements of the force fields within an acoustic standing wave using holographic optical tweezers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bassindale, P. G.; Drinkwater, B. W.; Phillips, D. B.

2014-04-21

Direct measurement of the forces experienced by micro-spheres in an acoustic standing wave device have been obtained using calibrated optical traps generated with holographic optical tweezers. A micro-sphere, which is optically trapped in three dimensions, can be moved through the acoustic device to measure forces acting upon it. When the micro-sphere is subjected to acoustic forces, it's equilibrium position is displaced to a position where the acoustic forces and optical forces are balanced. Once the optical trapping stiffness has been calibrated, observation of this displacement enables a direct measurement of the forces acting upon the micro-sphere. The measured forces aremore » separated into a spatially oscillating component, attributed to the acoustic radiation force, and a constant force, attributed to fluid streaming. As the drive conditions of the acoustic device were varied, oscillating forces (>2.5 pN{sub pp}) and streaming forces (<0.2 pN) were measured. A 5 μm silica micro-sphere was used to characterise a 6.8 MHz standing wave, λ = 220 μm, to a spatial resolution limited by the uncertainty in the positioning of the micro-sphere (here to within 2 nm) and with a force resolution on the order of 10 fN. The results have application in the design and testing of acoustic manipulation devices.« less

Bias and robustness of uncertainty components estimates in transient climate projections

NASA Astrophysics Data System (ADS)

Hingray, Benoit; Blanchet, Juliette; Jean-Philippe, Vidal

2016-04-01

A critical issue in climate change studies is the estimation of uncertainties in projections along with the contribution of the different uncertainty sources, including scenario uncertainty, the different components of model uncertainty and internal variability. Quantifying the different uncertainty sources faces actually different problems. For instance and for the sake of simplicity, an estimate of model uncertainty is classically obtained from the empirical variance of the climate responses obtained for the different modeling chains. These estimates are however biased. Another difficulty arises from the limited number of members that are classically available for most modeling chains. In this case, the climate response of one given chain and the effect of its internal variability may be actually difficult if not impossible to separate. The estimate of scenario uncertainty, model uncertainty and internal variability components are thus likely to be not really robust. We explore the importance of the bias and the robustness of the estimates for two classical Analysis of Variance (ANOVA) approaches: a Single Time approach (STANOVA), based on the only data available for the considered projection lead time and a time series based approach (QEANOVA), which assumes quasi-ergodicity of climate outputs over the whole available climate simulation period (Hingray and Saïd, 2014). We explore both issues for a simple but classical configuration where uncertainties in projections are composed of two single sources: model uncertainty and internal climate variability. The bias in model uncertainty estimates is explored from theoretical expressions of unbiased estimators developed for both ANOVA approaches. The robustness of uncertainty estimates is explored for multiple synthetic ensembles of time series projections generated with MonteCarlo simulations. For both ANOVA approaches, when the empirical variance of climate responses is used to estimate model uncertainty, the bias is always positive. It can be especially high with STANOVA. In the most critical configurations, when the number of members available for each modeling chain is small (< 3) and when internal variability explains most of total uncertainty variance (75% or more), the overestimation is higher than 100% of the true model uncertainty variance. The bias can be considerably reduced with a time series ANOVA approach, owing to the multiple time steps accounted for. The longer the transient time period used for the analysis, the larger the reduction. When a quasi-ergodic ANOVA approach is applied to decadal data for the whole 1980-2100 period, the bias is reduced by a factor 2.5 to 20 depending on the projection lead time. In all cases, the bias is likely to be not negligible for a large number of climate impact studies resulting in a likely large overestimation of the contribution of model uncertainty to total variance. For both approaches, the robustness of all uncertainty estimates is higher when more members are available, when internal variability is smaller and/or the response-to-uncertainty ratio is higher. QEANOVA estimates are much more robust than STANOVA ones: QEANOVA simulated confidence intervals are roughly 3 to 5 times smaller than STANOVA ones. Excepted for STANOVA when less than 3 members is available, the robustness is rather high for total uncertainty and moderate for internal variability estimates. For model uncertainty or response-to-uncertainty ratio estimates, the robustness is conversely low for QEANOVA to very low for STANOVA. In the most critical configurations (small number of member, large internal variability), large over- or underestimation of uncertainty components is very thus likely. To propose relevant uncertainty analyses and avoid misleading interpretations, estimates of uncertainty components should be therefore bias corrected and ideally come with estimates of their robustness. This work is part of the COMPLEX Project (European Collaborative Project FP7-ENV-2012 number: 308601; http://www.complex.ac.uk/). Hingray, B., Saïd, M., 2014. Partitioning internal variability and model uncertainty components in a multimodel multireplicate ensemble of climate projections. J.Climate. doi:10.1175/JCLI-D-13-00629.1 Hingray, B., Blanchet, J. (revision) Unbiased estimators for uncertainty components in transient climate projections. J. Climate Hingray, B., Blanchet, J., Vidal, J.P. (revision) Robustness of uncertainty components estimates in climate projections. J.Climate

Development and validation of a multilateration test bench for particle accelerator pre-alignment

NASA Astrophysics Data System (ADS)

Kamugasa, Solomon William; Rothacher, Markus; Gayde, Jean-Christophe; Mainaud Durand, Helene

2018-03-01

The development and validation of a portable coordinate measurement solution for fiducialization of compact linear collider (CLIC) components is presented. This new solution addresses two limitations of high-accuracy state-of-the-art coordinate measuring machines, i.e. lack of portability and limited measurement volume. The solution is based on frequency scanning interferometry (FSI) distances and the multilateration coordinate measurement technique. The developments include a reference sphere for localizing the FSI optical fiber tip and a kinematic mount for repositioning the reference sphere with sub-micrometric repeatability. This design enables absolute distance measurements in different directions from the same point, which is essential for multilateration. A multilateration test bench built using these prototypes has been used to fiducialize a CLIC cavity beam position monitor and 420 mm-long main beam quadrupole magnet. The combined fiducialization uncertainty achieved is 3.5 μm (k  =  1), which is better than the CLIC 5 μm (k  =  1) uncertainty specification.

Bi-Directional Brillouin Optical Time Domain Analyzer System for Long Range Distributed Sensing

PubMed Central

Guo, Nan; Wang, Liang; Wang, Jie; Jin, Chao; Tam, Hwa-Yaw; Zhang, A. Ping; Lu, Chao

2016-01-01

We propose and experimentally demonstrate a novel scheme of bi-directional Brillouin time domain analyzer (BD-BOTDA) to extend the sensing range. By deploying two pump-probe pairs at two different wavelengths, the Brillouin frequency shift (BFS) distribution over each half of the whole fiber can be obtained with the simultaneous detection of Brillouin signals in both channels. Compared to the conventional unidirectional BOTDA system of the same sensing range, the proposed BD-BOTDA scheme enables distributed sensing with a performance level comparable to the conventional one with half of the sensing range and a spatial resolution of 2 m, while maintaining the Brillouin signal-to-noise ratio (SNR) and the BFS uncertainty. Based on this technique, we have achieved distributed temperature sensing with a measurement range of 81.9 km fiber at a spatial resolution of 2 m and BFS uncertainty of ~0.44 MHz without introducing any complicated components or schemes. PMID:27999250

When 1+1 can be >2: Uncertainties compound when simulating climate, fisheries and marine ecosystems

NASA Astrophysics Data System (ADS)

Evans, Karen; Brown, Jaclyn N.; Sen Gupta, Alex; Nicol, Simon J.; Hoyle, Simon; Matear, Richard; Arrizabalaga, Haritz

2015-03-01

Multi-disciplinary approaches that combine oceanographic, biogeochemical, ecosystem, fisheries population and socio-economic models are vital tools for modelling whole ecosystems. Interpreting the outputs from such complex models requires an appreciation of the many different types of modelling frameworks being used and their associated limitations and uncertainties. Both users and developers of particular model components will often have little involvement or understanding of other components within such modelling frameworks. Failure to recognise limitations and uncertainties associated with components and how these uncertainties might propagate throughout modelling frameworks can potentially result in poor advice for resource management. Unfortunately, many of the current integrative frameworks do not propagate the uncertainties of their constituent parts. In this review, we outline the major components of a generic whole of ecosystem modelling framework incorporating the external pressures of climate and fishing. We discuss the limitations and uncertainties associated with each component of such a modelling system, along with key research gaps. Major uncertainties in modelling frameworks are broadly categorised into those associated with (i) deficient knowledge in the interactions of climate and ocean dynamics with marine organisms and ecosystems; (ii) lack of observations to assess and advance modelling efforts and (iii) an inability to predict with confidence natural ecosystem variability and longer term changes as a result of external drivers (e.g. greenhouse gases, fishing effort) and the consequences for marine ecosystems. As a result of these uncertainties and intrinsic differences in the structure and parameterisation of models, users are faced with considerable challenges associated with making appropriate choices on which models to use. We suggest research directions required to address these uncertainties, and caution against overconfident predictions. Understanding the full impact of uncertainty makes it clear that full comprehension and robust certainty about the systems themselves are not feasible. A key research direction is the development of management systems that are robust to this unavoidable uncertainty.

National Institute of Standards and Technology measurement service of the optical properties of biomedical phantoms: Current status.

PubMed

Lemaillet, Paul; Cooksey, Catherine C; Levine, Zachary H; Pintar, Adam L; Hwang, Jeeseong; Allen, David W

2016-03-24

The National Institute of Standards and Technology (NIST) has maintained scales for reflectance and transmittance over several decades. The scales are primarily intended for regular transmittance, mirrors, and solid surface scattering diffusers. The rapidly growing area of optical medical imaging needs a scale for volume scattering of diffuse materials that are used to mimic the optical properties of tissue. Such materials are used as phantoms to evaluate and validate instruments under development intended for clinical use. To address this need, a double-integrating sphere based instrument has been installed to measure the optical properties of tissue-mimicking phantoms. The basic system and methods have been described in previous papers. An important attribute in establishing a viable calibration service is the estimation of measurement uncertainties. The use of custom models and comparisons with other established scales enabled uncertainty measurements. Here, we describe the continuation of those efforts to advance the understanding of the uncertainties through two independent measurements: the bidirectional reflectance distribution function and the bidirectional transmittance distribution function of a commercially available solid biomedical phantom. A Monte Carlo-based model is used and the resulting optical properties are compared to the values provided by the phantom manufacturer.

Assessment of the Accuracy of the Conventional Ray-Tracing Technique: Implications in Remote Sensing and Radiative Transfer Involving Ice Clouds.

NASA Technical Reports Server (NTRS)

Bi, Lei; Yang, Ping; Liu, Chao; Yi, Bingqi; Baum, Bryan A.; Van Diedenhoven, Bastiaan; Iwabuchi, Hironobu

2014-01-01

A fundamental problem in remote sensing and radiative transfer simulations involving ice clouds is the ability to compute accurate optical properties for individual ice particles. While relatively simple and intuitively appealing, the conventional geometric-optics method (CGOM) is used frequently for the solution of light scattering by ice crystals. Due to the approximations in the ray-tracing technique, the CGOM accuracy is not well quantified. The result is that the uncertainties are introduced that can impact many applications. Improvements in the Invariant Imbedding T-matrix method (II-TM) and the Improved Geometric-Optics Method (IGOM) provide a mechanism to assess the aforementioned uncertainties. The results computed by the II-TMþIGOM are considered as a benchmark because the IITM solves Maxwell's equations from first principles and is applicable to particle size parameters ranging into the domain at which the IGOM has reasonable accuracy. To assess the uncertainties with the CGOM in remote sensing and radiative transfer simulations, two independent optical property datasets of hexagonal columns are developed for sensitivity studies by using the CGOM and the II-TMþIGOM, respectively. Ice cloud bulk optical properties obtained from the two datasets are compared and subsequently applied to retrieve the optical thickness and effective diameter from Moderate Resolution Imaging Spectroradiometer (MODIS) measurements. Additionally, the bulk optical properties are tested in broadband radiative transfer (RT) simulations using the general circulation model (GCM) version of the Rapid Radiative Transfer Model (RRTMG) that is adopted in the National Center for Atmospheric Research (NCAR) Community Atmosphere Model (CAM, version 5.1). For MODIS retrievals, the mean bias of uncertainties of applying the CGOM in shortwave bands (0.86 and 2.13 micrometers) can be up to 5% in the optical thickness and as high as 20% in the effective diameter, depending on cloud optical thickness and effective diameter. In the MODIS infrared window bands centered at 8.5, 11, and 12 micrometers biases in the optical thickness and effective diameter are up to 12% and 10%, respectively. The CGOM-based simulation errors in ice cloud radiative forcing calculations are on the order of 10Wm(exp 2).

A Hierarchical Multi-Model Approach for Uncertainty Segregation, Prioritization and Comparative Evaluation of Competing Modeling Propositions

NASA Astrophysics Data System (ADS)

Tsai, F. T.; Elshall, A. S.; Hanor, J. S.

2012-12-01

Subsurface modeling is challenging because of many possible competing propositions for each uncertain model component. How can we judge that we are selecting the correct proposition for an uncertain model component out of numerous competing propositions? How can we bridge the gap between synthetic mental principles such as mathematical expressions on one hand, and empirical observation such as observation data on the other hand when uncertainty exists on both sides? In this study, we introduce hierarchical Bayesian model averaging (HBMA) as a multi-model (multi-proposition) framework to represent our current state of knowledge and decision for hydrogeological structure modeling. The HBMA framework allows for segregating and prioritizing different sources of uncertainty, and for comparative evaluation of competing propositions for each source of uncertainty. We applied the HBMA to a study of hydrostratigraphy and uncertainty propagation of the Southern Hills aquifer system in the Baton Rouge area, Louisiana. We used geophysical data for hydrogeological structure construction through indictor hydrostratigraphy method and used lithologic data from drillers' logs for model structure calibration. However, due to uncertainty in model data, structure and parameters, multiple possible hydrostratigraphic models were produced and calibrated. The study considered four sources of uncertainties. To evaluate mathematical structure uncertainty, the study considered three different variogram models and two geological stationarity assumptions. With respect to geological structure uncertainty, the study considered two geological structures with respect to the Denham Springs-Scotlandville fault. With respect to data uncertainty, the study considered two calibration data sets. These four sources of uncertainty with their corresponding competing modeling propositions resulted in 24 calibrated models. The results showed that by segregating different sources of uncertainty, HBMA analysis provided insights on uncertainty priorities and propagation. In addition, it assisted in evaluating the relative importance of competing modeling propositions for each uncertain model component. By being able to dissect the uncertain model components and provide weighted representation of the competing propositions for each uncertain model component based on the background knowledge, the HBMA functions as an epistemic framework for advancing knowledge about the system under study.

Fundamental uncertainty limit of optical flow velocimetry according to Heisenberg's uncertainty principle.

PubMed

Fischer, Andreas

2016-11-01

Optical flow velocity measurements are important for understanding the complex behavior of flows. Although a huge variety of methods exist, they are either based on a Doppler or a time-of-flight measurement principle. Doppler velocimetry evaluates the velocity-dependent frequency shift of light scattered at a moving particle, whereas time-of-flight velocimetry evaluates the traveled distance of a scattering particle per time interval. Regarding the aim of achieving a minimal measurement uncertainty, it is unclear if one principle allows to achieve lower uncertainties or if both principles can achieve equal uncertainties. For this reason, the natural, fundamental uncertainty limit according to Heisenberg's uncertainty principle is derived for Doppler and time-of-flight measurement principles, respectively. The obtained limits of the velocity uncertainty are qualitatively identical showing, e.g., a direct proportionality for the absolute value of the velocity to the power of 32 and an indirect proportionality to the square root of the scattered light power. Hence, both measurement principles have identical potentials regarding the fundamental uncertainty limit due to the quantum mechanical behavior of photons. This fundamental limit can be attained (at least asymptotically) in reality either with Doppler or time-of-flight methods, because the respective Cramér-Rao bounds for dominating photon shot noise, which is modeled as white Poissonian noise, are identical with the conclusions from Heisenberg's uncertainty principle.

Optical Sensors for Planetary Radiant Energy (OSPREy): Calibration and Validation of Current and Next-Generation NASA Missions

NASA Technical Reports Server (NTRS)

Hooker, Stanford B.; Bernhard, Germar; Morrow, John H.; Booth, Charles R.; Comer, Thomas; Lind, Randall N.; Quang, Vi

2012-01-01

A principal objective of the Optical Sensors for Planetary Radiance Energy (OSPREy) activity is to establish an above-water radiometer system as a lower-cost alternative to existing in-water systems for the collection of ground-truth observations. The goal is to be able to make high-quality measurements satisfying the accuracy requirements for the vicarious calibration and algorithm validation of next-generation satellites that make ocean color and atmospheric measurements. This means the measurements will have a documented uncertainty satisfying the established performance metrics for producing climate-quality data records. The OSPREy approach is based on enhancing commercial-off-the-shelf fixed-wavelength and hyperspectral sensors to create hybridspectral instruments with an improved accuracy and spectral resolution, as well as a dynamic range permitting sea, Sun, sky, and Moon observations. Greater spectral diversity in the ultraviolet (UV) will be exploited to separate the living and nonliving components of marine ecosystems; UV bands will also be used to flag and improve atmospheric correction algorithms in the presence of absorbing aerosols. The short-wave infrared (SWIR) is expected to improve atmospheric correction, because the ocean is radiometrically blacker at these wavelengths. This report describes the development of the sensors, including unique capabilities like three-axis polarimetry; the documented uncertainty will be presented in a subsequent report.

Development of traceable measurement of the diffuse optical properties of solid reference standards for biomedical optics at National Institute of Standards and Technology.

PubMed

Lemaillet, Paul; Bouchard, Jean-Pierre; Allen, David W

2015-07-01

The development of a national reference instrument dedicated to the measurement of the scattering and absorption properties of solid tissue-mimicking phantoms used as reference standards is presented. The optical properties of the phantoms are measured with a double-integrating sphere setup in the steady-state domain, coupled with an inversion routine of the adding-doubling procedure that allows for the computation of the uncertainty budget for the measurements. The results are compared to the phantom manufacturer's values obtained by a time-resolved approach. The results suggest that the agreement between these two independent methods is within the estimated uncertainties. This new reference instrument will provide optical biomedical research laboratories with reference values for absolute diffuse optical properties of phantom materials.

Combining external and internal mixing representation of atmospheric aerosol for optical properties calculations: focus on absorption properties over Europe and North America using AERONET observations and AQMEII simulations

NASA Astrophysics Data System (ADS)

Curci, Gabriele

2017-04-01

The calculation of optical properties from knowledge of the composition and abundance of atmospheric aerosol implies a certain number of assumptions. First and if not known or explicitly simulated, a size distribution must be assigned to each aerosol component (e.g. sulfate-like inorganic ions, organic and back carbon, soil dust, sea salt). Second, physical-chemical properties such as the shape, density, complex refractive index, and hygroscopic factors must be associated to each aerosol species. Third, a representation of how the aerosol species combine together must be made: among those, the most popular are the assumptions of external mixing, in which each particle is assumed to be formed of a single compound and the optical properties may be calculated separately for each species, or of internal core-shell arrangement, in which each particle consists of a water-insoluble core coated with a water-soluble shell and that requires more elaborate calculations for optical properties. Previous work found that the assumption on the mixing state (external or core-shell internal) is the one that introduces the highest uncertainty, quantified in about 30% uncertainty on the calculation of monthly mean aerosol optical depth (AOD) and single-scattering albedo (SSA). The external mixing assumption is generally more reasonable for freshly emitted aerosol, while the internal mixing case is associated with aged aerosol that had the time to form the coating around the core. Both approximations are thus regarded as valid, but in general a combination of the two mixing states may be expected in a given air mass. In this work, we test a simple empirical parameterization of the fraction of internally mixed particles (F_in) in a generic air mass. The F_in fraction is calculated in two alternative ways, one exploiting the NOz to NOx ratio (proxy of the photochemical aging), and the other using the relative abundance of black carbon with respect to other aerosol components (proxy of the coating formation). We compare sunphotometer observations from the AERosol RObotic NETwork (AERONET, http://aeronet.gsfc.nasa.gov/) across Europe and North America for the year 2010 with simulations from the Air Quality Modeling Evaluation International Initiative (AQMEII, http://aqmeii.jrc.ec.europa.eu/). The calculation of optical properties from simulated aerosol profiles is carried out using a single post-processing tool (FlexAOD, http://pumpkin.aquila.infn.it/flexaod/) that allows explicit and flexible assignment of the underlying assumptions mentioned above. We found that the combination of externally and internally mixed particles weighted through the F_in fraction gives the best agreement between models and observations, in particular regarding the single-scattering albedo.

Metrology for the manufacturing of freeform optics

NASA Astrophysics Data System (ADS)

Blalock, Todd; Myer, Brian; Ferralli, Ian; Brunelle, Matt; Lynch, Tim

2017-10-01

Recently the use of freeform surfaces have become a realization for optical designers. These non-symmetrical optical surfaces have allowed unique solutions to optical design problems. The implementation of freeform optical surfaces has been limited by manufacturing capabilities and quality. However over the past several years freeform fabrication processes have improved in capability and precision. But as with any manufacturing, proper metrology is required to monitor and verify the process. Typical optics metrology such as interferometry has its challenges and limitations with the unique shapes of freeform optics. Two contact metrology methods for freeform metrology are presented; a Leitz coordinate measurement machine (CMM) with an uncertainty of +/- 0.5 μm and a high resolution profilometer (Panasonic UA3P) with a measurement uncertainty of +/- 0.05 μm. We are also developing a non-contact high resolution technique based on the fringe reflection technique known as deflectometry. This fast non-contact metrology has the potential to compete with accuracies of the contact methods but also can acquire data in seconds rather than minutes or hours.

Extending "Deep Blue" aerosol retrieval coverage to cases of absorbing aerosols above clouds: Sensitivity analysis and first case studies

NASA Astrophysics Data System (ADS)

Sayer, A. M.; Hsu, N. C.; Bettenhausen, C.; Lee, J.; Redemann, J.; Schmid, B.; Shinozuka, Y.

2016-05-01

Cases of absorbing aerosols above clouds (AACs), such as smoke or mineral dust, are omitted from most routinely processed space-based aerosol optical depth (AOD) data products, including those from the Moderate Resolution Imaging Spectroradiometer (MODIS). This study presents a sensitivity analysis and preliminary algorithm to retrieve above-cloud AOD and liquid cloud optical depth (COD) for AAC cases from MODIS or similar sensors, for incorporation into a future version of the "Deep Blue" AOD data product. Detailed retrieval simulations suggest that these sensors should be able to determine AAC AOD with a typical level of uncertainty ˜25-50% (with lower uncertainties for more strongly absorbing aerosol types) and COD with an uncertainty ˜10-20%, if an appropriate aerosol optical model is known beforehand. Errors are larger, particularly if the aerosols are only weakly absorbing, if the aerosol optical properties are not known, and the appropriate model to use must also be retrieved. Actual retrieval errors are also compared to uncertainty envelopes obtained through the optimal estimation (OE) technique; OE-based uncertainties are found to be generally reasonable for COD but larger than actual retrieval errors for AOD, due in part to difficulties in quantifying the degree of spectral correlation of forward model error. The algorithm is also applied to two MODIS scenes (one smoke and one dust) for which near-coincident NASA Ames Airborne Tracking Sun photometer (AATS) data were available to use as a ground truth AOD data source, and found to be in good agreement, demonstrating the validity of the technique with real observations.

What is the Uncertainty in MODIS Aerosol Optical Depth in the Vicinity of Clouds?

NASA Technical Reports Server (NTRS)

Patadia, Falguni; Levy, Rob; Mattoo, Shana

2017-01-01

MODIS dark-target (DT) algorithm retrieves aerosol optical depth (AOD) using a Look Up Table (LUT) approach. Global comparison of AOD (Collection 6 ) with ground-based sun photometer gives an Estimated Error (EE) of +/-(0.04 + 10%) over ocean. However, EE does not represent per-retrieval uncertainty. For retrievals that are biased high compared to AERONET, here we aim to closely examine the contribution of biases due to presence of clouds and per-pixel retrieval uncertainty. We have characterized AOD uncertainty at 550 nm, due to standard deviation of reflectance in 10 km retrieval region, uncertainty related to gas (H2O, O3) absorption, surface albedo, and aerosol models. The uncertainty in retrieved AOD seems to lie within the estimated over ocean error envelope of +/-(0.03+10%). Regions between broken clouds tend to have higher uncertainty. Compared to C6 AOD, a retrieval omitting observations in the vicinity of clouds (< or = 1 km) is biased by about +/- 0.05. For homogeneous aerosol distribution, clear sky retrievals show near zero bias. Close look at per-pixel reflectance histograms suggests retrieval possibility using median reflectance values.

Calibrated intercepts for solar radiometers used in remote sensor calibration

NASA Technical Reports Server (NTRS)

Gellman, David I.; Biggar, Stuart F.; Slater, Philip N.; Bruegge, Carol J.

1991-01-01

Calibrated solar radiometer intercepts allow spectral optical depths to be determined for days with intermittently clear skies. This is of particular importance on satellite sensor calibration days that are cloudy except at the time of image acquisition. This paper describes the calibration of four solar radiometers using the Langley-Bouguer technique for data collected on days with a clear, stable atmosphere. Intercepts are determined with an uncertainty of less than six percent, corresponding to a maximum uncertainty of 0.06 in optical depth. The spread of voltage intercepts calculated in this process is carried through three methods of radiometric calibration of satellite sensors to yield an uncertainty in radiance at the top of the atmosphere of less than one percent associated with the uncertainty in solar radiometer intercepts for a range of ground reflectances.

Absolute frequency list of the ν3-band transitions of methane at a relative uncertainty level of 10(-11).

PubMed

Okubo, Sho; Nakayama, Hirotaka; Iwakuni, Kana; Inaba, Hajime; Sasada, Hiroyuki

2011-11-21

We determine the absolute frequencies of 56 rotation-vibration transitions of the ν(3) band of CH(4) from 88.2 to 90.5 THz with a typical uncertainty of 2 kHz corresponding to a relative uncertainty of 2.2 × 10(-11) over an average time of a few hundred seconds. Saturated absorption lines are observed using a difference-frequency-generation source and a cavity-enhanced absorption cell, and the transition frequencies are measured with a fiber-laser-based optical frequency comb referenced to a rubidium atomic clock linked to the international atomic time. The determined value of the P(7) F(2)((2)) line is consistent with the International Committee for Weights and Measures recommendation within the uncertainty. © 2011 Optical Society of America

Direct Aerosol Radiative Forcing: Calculations and Measurements from the Tropospheric

NASA Technical Reports Server (NTRS)

Russell, P. B.; Hignett, P.; Stowe, L. L.; Livingston, J. M.; Kinne, S.; Wong, J.; Chan, K. Roland (Technical Monitor)

1997-01-01

Radiative forcing is defined as the change in the net (downwelling minus upwelling) radiative flux at a given level in the atmosphere. This net flux is the radiative power density available to drive climatic processes in the earth-atmosphere system below that level. Recent research shows that radiative forcing by aerosol particles is a major source of uncertainty in climate predictions. To reduce those uncertainties, TARFOX was designed to determine direct (cloud-free) radiative forcing by the aerosols in one of the world's major industrial pollution plumes--that flowing from the east coast of the US over the Atlantic Ocean. TARFOX measured a variety of aerosol radiative effects (including direct forcing) while simultaneously measuring the chemical, physical, and optical properties of the aerosol particles causing those effects. The resulting data sets permit a wide variety of tests of the consistency, or closure, among the measurements and the models that link them. Because climate predictions use the same or similar model components, closure tests help to assess and reduce prediction uncertainties. In this work we use the TARFOX-determined aerosol, gas, and surface properties to compute radiative forcing for a variety of aerosol episodes, with inadvisable optical depths ranging from 0.07 to 0.6. We calculate forcing by several techniques with varying degrees of sophistication, in part to test the range of applicability of simplified techniques--which are often the only ones feasible in climate predictions by general circulation models (GCMs). We then compare computed forcing to that determined from: (1) Upwelling and downwelling fluxes (0.3-0.7 mm and 0.7-3.0 mm) measured by radiometers on the UK MRF C-130. and (2) Daily average cloud-free absorbed solar and emitted thermal radiative flux at the top of the atmosphere derived from the AVHRR radiometer on the NOAA- 14 satellite. The calculations and measurements all yield aerosol direct radiative forcing in the range -50 to -190 W sq m per unit inadvisable optical depth. The magnitudes are about 15 to 100 times larger than the global-average direct forcing expected for the global-average sulfate aerosol optical depth of 0.04. The reasons for the larger forcing in TARFOX include the relatively large optical depths and the focus on cloud-free, daytime conditions over the dark ocean surface. These are the conditions that produce the actual major radiative forcing events that contribute to any global-average climate effect. Detailed comparisons of calculated and measured forcings for specific events are used for more refined tests of closure.

A Bayes network approach to uncertainty quantification in hierarchically developed computational models

DOE PAGES

Urbina, Angel; Mahadevan, Sankaran; Paez, Thomas L.

2012-03-01

Here, performance assessment of complex systems is ideally accomplished through system-level testing, but because they are expensive, such tests are seldom performed. On the other hand, for economic reasons, data from tests on individual components that are parts of complex systems are more readily available. The lack of system-level data leads to a need to build computational models of systems and use them for performance prediction in lieu of experiments. Because their complexity, models are sometimes built in a hierarchical manner, starting with simple components, progressing to collections of components, and finally, to the full system. Quantification of uncertainty inmore » the predicted response of a system model is required in order to establish confidence in the representation of actual system behavior. This paper proposes a framework for the complex, but very practical problem of quantification of uncertainty in system-level model predictions. It is based on Bayes networks and uses the available data at multiple levels of complexity (i.e., components, subsystem, etc.). Because epistemic sources of uncertainty were shown to be secondary, in this application, aleatoric only uncertainty is included in the present uncertainty quantification. An example showing application of the techniques to uncertainty quantification of measures of response of a real, complex aerospace system is included.« less

Uncertainty in recharge estimation: impact on groundwater vulnerability assessments for the Pearl Harbor Basin, O'ahu, Hawai'i, U.S.A.

NASA Astrophysics Data System (ADS)

Giambelluca, Thomas W.; Loague, Keith; Green, Richard E.; Nullet, Michael A.

1996-06-01

In this paper, uncertainty in recharge estimates is investigated relative to its impact on assessments of groundwater contamination vulnerability using a relatively simple pesticide mobility index, attenuation factor (AF). We employ a combination of first-order uncertainty analysis (FOUA) and sensitivity analysis to investigate recharge uncertainties for agricultural land on the island of O'ahu, Hawai'i, that is currently, or has been in the past, under sugarcane or pineapple cultivation. Uncertainty in recharge due to recharge component uncertainties is 49% of the mean for sugarcane and 58% of the mean for pineapple. The components contributing the largest amounts of uncertainty to the recharge estimate are irrigation in the case of sugarcane and precipitation in the case of pineapple. For a suite of pesticides formerly or currently used in the region, the contribution to AF uncertainty of recharge uncertainty was compared with the contributions of other AF components: retardation factor (RF), a measure of the effects of sorption; soil-water content at field capacity (ΘFC); and pesticide half-life (t1/2). Depending upon the pesticide, the contribution of recharge to uncertainty ranks second or third among the four AF components tested. The natural temporal variability of recharge is another source of uncertainty in AF, because the index is calculated using the time-averaged recharge rate. Relative to the mean, recharge variability is 10%, 44%, and 176% for the annual, monthly, and daily time scales, respectively, under sugarcane, and 31%, 112%, and 344%, respectively, under pineapple. In general, uncertainty in AF associated with temporal variability in recharge at all time scales exceeds AF. For chemicals such as atrazine or diuron under sugarcane, and atrazine or bromacil under pineapple, the range of AF uncertainty due to temporal variability in recharge encompasses significantly higher levels of leaching potential at some locations than that indicated by the AF estimate.

Uncertainty of Passive Imager Cloud Optical Property Retrievals to Instrument Radiometry and Model Assumptions: Examples from MODIS

NASA Technical Reports Server (NTRS)

Platnick, Steven; Wind, Galina; Meyer, Kerry; Amarasinghe, Nandana; Arnold, G. Thomas; Zhang, Zhibo; King, Michael D.

2013-01-01

The optical and microphysical structure of clouds is of fundamental importance for understanding a variety of cloud radiation and precipitation processes. With the advent of MODIS on the NASA EOS Terra and Aqua platforms, simultaneous global-daily 1 km retrievals of cloud optical thickness (COT) and effective particle radius (CER) are provided, as well as the derived water path (WP). The cloud product (MOD06/MYD06 for MODIS Terra and Aqua, respectively) provides separate retrieval datasets for various two-channel retrievals, typically a VISNIR channel paired with a 1.6, 2.1, and 3.7 m spectral channel. The MOD06 forward model is derived from on a homogeneous plane-parallel cloud. In Collection 5 processing (completed in 2007 with a modified Collection 5.1 completed in 2010), pixel-level retrieval uncertainties were calculated for the following non-3-D error sources: radiometry, surface spectral albedo, and atmospheric corrections associated with model analysis uncertainties (water vapor only). The latter error source includes error correlation across the retrieval spectral channels. Estimates of uncertainty in 1 aggregated (Level-3) means were also provided assuming unity correlation between error sources for all pixels in a grid for a single day, and zero correlation of error sources from one day to the next. I n Collection 6 (expected to begin in late summer 2013) we expanded the uncertainty analysis to include: (a) scene-dependent calibration uncertainty that depends on new band and detector-specific Level 1B uncertainties, (b) new model error sources derived from the look-up tables which includes sensitivities associated with wind direction over the ocean and uncertainties in liquid water and ice effective variance, (c) thermal emission uncertainties in the 3.7 m band associated with cloud and surface temperatures that are needed to extract reflected solar radiation from the total radiance signal, (d) uncertainty in the solar spectral irradiance at 3.7 m, and (e) addition of stratospheric ozone uncertainty in visible atmospheric corrections. A summary of the approach and example Collection 6 results will be shown.

Determination of the fine structure constant based on BLOCH oscillations of ultracold atoms in a vertical optical lattice.

PubMed

Cladé, Pierre; de Mirandes, Estefania; Cadoret, Malo; Guellati-Khélifa, Saïda; Schwob, Catherine; Nez, François; Julien, Lucile; Biraben, François

2006-01-27

We report an accurate measurement of the recoil velocity of 87Rb atoms based on Bloch oscillations in a vertical accelerated optical lattice. We transfer about 900 recoil momenta with an efficiency of 99.97% per recoil. A set of 72 measurements of the recoil velocity, each one with a relative uncertainty of about 33 ppb in 20 min integration time, leads to a determination of the fine structure constant with a statistical relative uncertainty of 4.4 ppb. The detailed analysis of the different systematic errors yields to a relative uncertainty of 6.7 ppb. The deduced value of alpha-1 is 137.035 998 78(91).

Host Model Uncertainty in Aerosol Radiative Effects: the AeroCom Prescribed Experiment and Beyond

NASA Astrophysics Data System (ADS)

Stier, Philip; Schutgens, Nick; Bian, Huisheng; Boucher, Olivier; Chin, Mian; Ghan, Steven; Huneeus, Nicolas; Kinne, Stefan; Lin, Guangxing; Myhre, Gunnar; Penner, Joyce; Randles, Cynthia; Samset, Bjorn; Schulz, Michael; Yu, Hongbin; Zhou, Cheng; Bellouin, Nicolas; Ma, Xiaoyan; Yu, Fangqun; Takemura, Toshihiko

2013-04-01

Anthropogenic and natural aerosol radiative effects are recognized to affect global and regional climate. Multi-model "diversity" in estimates of the aerosol radiative effect is often perceived as a measure of the uncertainty in modelling aerosol itself. However, current aerosol models vary considerably in model components relevant for the calculation of aerosol radiative forcings and feedbacks and the associated "host-model uncertainties" are generally convoluted with the actual uncertainty in aerosol modelling. In the AeroCom Prescribed intercomparison study we systematically isolate and quantify host model uncertainties on aerosol forcing experiments through prescription of identical aerosol radiative properties in eleven participating models. Host model errors in aerosol radiative forcing are largest in regions of uncertain host model components, such as stratocumulus cloud decks or areas with poorly constrained surface albedos, such as sea ice. Our results demonstrate that host model uncertainties are an important component of aerosol forcing uncertainty that require further attention. However, uncertainties in aerosol radiative effects also include short-term and long-term feedback processes that will be systematically explored in future intercomparison studies. Here we will present an overview of the proposals for discussion and results from early scoping studies.

Interstellar matter in Shapley-Ames elliptical galaxies. IV. A diffusely distributed component of dust and its effect on colour gradients.

NASA Astrophysics Data System (ADS)

Goudfrooij, P.; de Jong, T.

1995-06-01

We have investigated IRAS far-infrared observations of a complete, blue magnitude limited sample of 56 elliptical galaxies selected from the Revised Shapley-Ames Catalog. Data from a homogeneous optical CCD imaging survey as well as published X-ray data from the EINSTEIN satellite are used to constrain the infrared data. Dust masses as determined from the IRAS flux densities are found to be roughly an order of magnitude higher than those determined from optical extinction values of dust lanes and patches, in strong contrast with the situation in spiral galaxies. This "mass discrepancy" is found to be independent of the (apparent) inclination of the dust lanes. To resolve this dilemma we postulate that the majority of the dust in elliptical galaxies exists as a diffusely distributed component of dust which is undetectable at optical wavelengths. Using observed radial optical surface brightness profiles, we have systematically investigated possible heating mechanisms for the dust within elliptical galaxies. We find that heating of the dust in elliptical galaxies by the interstellar radiation field is generally sufficient to account for the dust temperatures as indicated by the IRAS flux densities. Collisions of dust grains with hot electrons in elliptical galaxies which are embedded in a hot, X-ray-emitting gas is found to be another effective heating mechanism for the dust. Employing model calculations which involve the transfer of stellar radiation in a spherical distribution of stars mixed with a diffuse distribution of dust, we show that the observed infrared luminosities imply total dust optical depths of the postulated diffusely distributed dust component in the range 0.1<~τ_V_<~0.7 and radial colour gradients 0.03<~{DELTA}(B-I)/{DELTA}log r<~0.25. The observed IRAS flux densities can be reproduced within the 1σ uncertainties in virtually all ellipticals in this sample by this newly postulated dust component, diffusely distributed over the inner few kpc of the galaxies, and heated by optical photons and/or hot electrons. The radial colour gradients implied by the diffuse dust component are found to be smaller than or equal to the observed colour gradients. Thus, we argue that the effect of dust extinction should be taken seriously in the interpretation of colour gradients in elliptical galaxies. We show that the amount of dust observed in luminous elliptical galaxies is generally higher than that expected from production by mass loss of stars within elliptical galaxies and destruction by sputtering in hot gas. This suggests that most of the dust in elliptical galaxies generally has an external origin.

Quantifying the sensitivity of aerosol optical depths retrieved from MSG SEVIRI to a priori data

NASA Astrophysics Data System (ADS)

Bulgin, C. E.; Palmer, P. I.; Merchant, C. J.; Siddans, R.; Poulsen, C.; Grainger, R. G.; Thomas, G.; Carboni, E.; McConnell, C.; Highwood, E.

2009-12-01

Radiative forcing contributions from aerosol direct and indirect effects remain one of the most uncertain components of the climate system. Satellite observations of aerosol optical properties offer important constraints on atmospheric aerosols but their sensitivity to prior assumptions must be better characterized before they are used effectively to reduce uncertainty in aerosol radiative forcing. We assess the sensitivity of the Oxford-RAL Aerosol and Cloud (ORAC) optimal estimation retrieval of aerosol optical depth (AOD) from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) to a priori aerosol data. SEVIRI is a geostationary satellite instrument centred over Africa and the neighbouring Atlantic Ocean, routinely sampling desert dust and biomass burning outflow from Africa. We quantify the uncertainty in SEVIRI AOD retrievals in the presence of desert dust by comparing retrievals that use prior information from the Optical Properties of Aerosol and Cloud (OPAC) database, with those that use measured aerosol properties during the Dust Outflow and Deposition to the Ocean (DODO) aircraft campaign (August, 2006). We also assess the sensitivity of retrieved AODs to changes in solar zenith angle, and the vertical profile of aerosol effective radius and extinction coefficient input into the retrieval forward model. Currently the ORAC retrieval scheme retrieves AODs for five aerosol types (desert dust, biomass burning, maritime, urban and continental) and chooses the most appropriate AOD based on the cost functions. We generate an improved prior aerosol speciation database for SEVIRI based on a statistical analysis of a Saharan Dust Index (SDI) determined using variances of different brightness temperatures, and organic and black carbon tracers from the GEOS-Chem chemistry transport model. This database is described as a function of season and time of day. We quantify the difference in AODs between those chosen based on prior information from the SDI and GEOS-Chem and those chosen based on the smallest cost function.

Leaf area index uncertainty estimates for model-data fusion applications

Treesearch

Andrew D. Richardson; D. Bryan Dail; D.Y. Hollinger

2011-01-01

Estimates of data uncertainties are required to integrate different observational data streams as model constraints using model-data fusion. We describe an approach with which random and systematic uncertainties in optical measurements of leaf area index [LAI] can be quantified. We use data from a measurement campaign at the spruce-dominated Howland Forest AmeriFlux...

National Institute of Standards and Technology measurement service of the optical properties of biomedical phantoms: Current status

PubMed Central

Lemaillet, Paul; Cooksey, Catherine C.; Levine, Zachary H.; Pintar, Adam L.; Hwang, Jeeseong; Allen, David W.

2016-01-01

The National Institute of Standards and Technology (NIST) has maintained scales for reflectance and transmittance over several decades. The scales are primarily intended for regular transmittance, mirrors, and solid surface scattering diffusers. The rapidly growing area of optical medical imaging needs a scale for volume scattering of diffuse materials that are used to mimic the optical properties of tissue. Such materials are used as phantoms to evaluate and validate instruments under development intended for clinical use. To address this need, a double-integrating sphere based instrument has been installed to measure the optical properties of tissue-mimicking phantoms. The basic system and methods have been described in previous papers. An important attribute in establishing a viable calibration service is the estimation of measurement uncertainties. The use of custom models and comparisons with other established scales enabled uncertainty measurements. Here, we describe the continuation of those efforts to advance the understanding of the uncertainties through two independent measurements: the bidirectional reflectance distribution function and the bidirectional transmittance distribution function of a commercially available solid biomedical phantom. A Monte Carlo-based model is used and the resulting optical properties are compared to the values provided by the phantom manufacturer. PMID:27453623

Proposed standardized definitions for vertical resolution and uncertainty in the NDACC lidar ozone and temperature algorithms - Part 2: Ozone DIAL uncertainty budget

NASA Astrophysics Data System (ADS)

Leblanc, Thierry; Sica, Robert J.; van Gijsel, Joanna A. E.; Godin-Beekmann, Sophie; Haefele, Alexander; Trickl, Thomas; Payen, Guillaume; Liberti, Gianluigi

2016-08-01

A standardized approach for the definition, propagation, and reporting of uncertainty in the ozone differential absorption lidar data products contributing to the Network for the Detection for Atmospheric Composition Change (NDACC) database is proposed. One essential aspect of the proposed approach is the propagation in parallel of all independent uncertainty components through the data processing chain before they are combined together to form the ozone combined standard uncertainty. The independent uncertainty components contributing to the overall budget include random noise associated with signal detection, uncertainty due to saturation correction, background noise extraction, the absorption cross sections of O3, NO2, SO2, and O2, the molecular extinction cross sections, and the number densities of the air, NO2, and SO2. The expression of the individual uncertainty components and their step-by-step propagation through the ozone differential absorption lidar (DIAL) processing chain are thoroughly estimated. All sources of uncertainty except detection noise imply correlated terms in the vertical dimension, which requires knowledge of the covariance matrix when the lidar signal is vertically filtered. In addition, the covariance terms must be taken into account if the same detection hardware is shared by the lidar receiver channels at the absorbed and non-absorbed wavelengths. The ozone uncertainty budget is presented as much as possible in a generic form (i.e., as a function of instrument performance and wavelength) so that all NDACC ozone DIAL investigators across the network can estimate, for their own instrument and in a straightforward manner, the expected impact of each reviewed uncertainty component. In addition, two actual examples of full uncertainty budget are provided, using nighttime measurements from the tropospheric ozone DIAL located at the Jet Propulsion Laboratory (JPL) Table Mountain Facility, California, and nighttime measurements from the JPL stratospheric ozone DIAL located at Mauna Loa Observatory, Hawai'i.

Many Point Optical Velocimetry for Gas Gun Applications

NASA Astrophysics Data System (ADS)

Pena, Michael; Becker, Steven; Garza, Anselmo; Hanache, Michael; Hixson, Robert; Jennings, Richard; Matthes, Melissa; O'Toole, Brendan; Roy, Shawoon; Trabia, Mohamed

2015-06-01

With the emergence of the multiplexed photonic Doppler velocimeter (MPDV), it is now practical to record many velocity traces simultaneously on shock physics experiments. Optical measurements of plastic deformation during high velocity impact have historically been constrained to a few measurement points. We have applied a 32-channel MPDV system to gas gun experiments in order to measure plastic deformation of a steel plate. A two dimensional array of measurement points allowed for diagnostic coverage over a large surface area of the target plate. This provided experimental flexibility to accommodate platform uncertainties as well as provide for a wealth of data from a given experiment. The two dimensional array of measurement points was imaged from an MT fiber-optic connector using off-the-shelf optical components to allow for an economical and easy-to-assemble, many-fiber probe. A two-stage, light gas gun was used to launch a Lexan projectile at velocities ranging from 4 to 6 km/s at a 12.7 mm thick A36 steel plate. Plastic deformation of the back surface was measured and compared with simulations from two different models: LS-DYNA and CTH. Comparison of results indicates that the computational analysis using both codes can reasonably simulate experiments of this type.

Extending "Deep Blue" Aerosol Retrieval Coverage to Cases of Absorbing Aerosols Above Clouds: Sensitivity Analysis and First Case Studies

NASA Technical Reports Server (NTRS)

Sayer, A. M.; Hsu, N. C.; Bettenhausen, C.; Lee, J.; Redemann, J.; Schmid, B.; Shinozuka, Y.

2016-01-01

Cases of absorbing aerosols above clouds (AACs), such as smoke or mineral dust, are omitted from most routinely processed space-based aerosol optical depth (AOD) data products, including those from the Moderate Resolution Imaging Spectroradiometer (MODIS). This study presents a sensitivity analysis and preliminary algorithm to retrieve above-cloud AOD and liquid cloud optical depth (COD) for AAC cases from MODIS or similar sensors, for incorporation into a future version of the "Deep Blue" AOD data product. Detailed retrieval simulations suggest that these sensors should be able to determine AAC AOD with a typical level of uncertainty approximately 25-50 percent (with lower uncertainties for more strongly absorbing aerosol types) and COD with an uncertainty approximately10-20 percent, if an appropriate aerosol optical model is known beforehand. Errors are larger, particularly if the aerosols are only weakly absorbing, if the aerosol optical properties are not known, and the appropriate model to use must also be retrieved. Actual retrieval errors are also compared to uncertainty envelopes obtained through the optimal estimation (OE) technique; OE-based uncertainties are found to be generally reasonable for COD but larger than actual retrieval errors for AOD, due in part to difficulties in quantifying the degree of spectral correlation of forward model error. The algorithm is also applied to two MODIS scenes (one smoke and one dust) for which near-coincident NASA Ames Airborne Tracking Sun photometer (AATS) data were available to use as a ground truth AOD data source, and found to be in good agreement, demonstrating the validity of the technique with real observations.

Assessment of the uncertainties in the Radiological Protection Institute of Ireland (RPII) radon measurements service.

PubMed

Hanley, O; Gutiérrez-Villanueva, J L; Currivan, L; Pollard, D

2008-10-01

The RPII radon (Rn) laboratory holds accreditation for the International Standard ISO/IEC 17025. A requirement of this standard is an estimate of the uncertainty of measurement. This work shows two approaches to estimate the uncertainty. The bottom-up approach involved identifying the components that were found to contribute to the uncertainty. Estimates were made for each of these components, which were combined to give a combined uncertainty of 13.5% at a Rn concentration of approximately 2500 Bq m(-3) at the 68% confidence level. By applying a coverage factor of k=2, the expanded uncertainty is +/-27% at the 95% confidence level. The top-down approach used information previously gathered from intercomparison exercises to estimate the uncertainty. This investigation found an expanded uncertainty of +/-22% at approximately 95% confidence level. This is good agreement for such independent estimates.

Wave-optics uncertainty propagation and regression-based bias model in GNSS radio occultation bending angle retrievals

NASA Astrophysics Data System (ADS)

Gorbunov, Michael E.; Kirchengast, Gottfried

2018-01-01

A new reference occultation processing system (rOPS) will include a Global Navigation Satellite System (GNSS) radio occultation (RO) retrieval chain with integrated uncertainty propagation. In this paper, we focus on wave-optics bending angle (BA) retrieval in the lower troposphere and introduce (1) an empirically estimated boundary layer bias (BLB) model then employed to reduce the systematic uncertainty of excess phases and bending angles in about the lowest 2 km of the troposphere and (2) the estimation of (residual) systematic uncertainties and their propagation together with random uncertainties from excess phase to bending angle profiles. Our BLB model describes the estimated bias of the excess phase transferred from the estimated bias of the bending angle, for which the model is built, informed by analyzing refractivity fluctuation statistics shown to induce such biases. The model is derived from regression analysis using a large ensemble of Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) RO observations and concurrent European Centre for Medium-Range Weather Forecasts (ECMWF) analysis fields. It is formulated in terms of predictors and adaptive functions (powers and cross products of predictors), where we use six main predictors derived from observations: impact altitude, latitude, bending angle and its standard deviation, canonical transform (CT) amplitude, and its fluctuation index. Based on an ensemble of test days, independent of the days of data used for the regression analysis to establish the BLB model, we find the model very effective for bias reduction and capable of reducing bending angle and corresponding refractivity biases by about a factor of 5. The estimated residual systematic uncertainty, after the BLB profile subtraction, is lower bounded by the uncertainty from the (indirect) use of ECMWF analysis fields but is significantly lower than the systematic uncertainty without BLB correction. The systematic and random uncertainties are propagated from excess phase to bending angle profiles, using a perturbation approach and the wave-optical method recently introduced by Gorbunov and Kirchengast (2015), starting with estimated excess phase uncertainties. The results are encouraging and this uncertainty propagation approach combined with BLB correction enables a robust reduction and quantification of the uncertainties of excess phases and bending angles in the lower troposphere.

Global statistics of microphysical properties of cloud-top ice crystals

NASA Astrophysics Data System (ADS)

van Diedenhoven, B.; Fridlind, A. M.; Cairns, B.; Ackerman, A. S.; Riedi, J.

2017-12-01

Ice crystals in clouds are highly complex. Their sizes, macroscale shape (i.e., habit), mesoscale shape (i.e., aspect ratio of components) and microscale shape (i.e., surface roughness) determine optical properties and affect physical properties such as fall speeds, growth rates and aggregation efficiency. Our current understanding on the formation and evolution of ice crystals under various conditions can be considered poor. Commonly, ice crystal size and shape are related to ambient temperature and humidity, but global observational statistics on the variation of ice crystal size and particularly shape have not been available. Here we show results of a project aiming to infer ice crystal size, shape and scattering properties from a combination of MODIS measurements and POLDER-PARASOL multi-angle polarimetry. The shape retrieval procedure infers the mean aspect ratios of components of ice crystals and the mean microscale surface roughness levels, which are quantifiable parameters that mostly affect the scattering properties, in contrast to "habit". We present global statistics on the variation of ice effective radius, component aspect ratio, microscale surface roughness and scattering asymmetry parameter as a function of cloud top temperature, latitude, location, cloud type, season, etc. Generally, with increasing height, sizes decrease, roughness increases, asymmetry parameters decrease and aspect ratios increase towards unity. Some systematic differences are observed for clouds warmer and colder than the homogeneous freezing level. Uncertainties in the retrievals will be discussed. These statistics can be used as observational targets for modeling efforts and to better constrain other satellite remote sensing applications and their uncertainties.

Global Statistics of Microphysical Properties of Cloud-Top Ice Crystals

NASA Technical Reports Server (NTRS)

Van Diedenhoven, Bastiaan; Fridlind, Ann; Cairns, Brian; Ackerman, Andrew; Riedl, Jerome

2017-01-01

Ice crystals in clouds are highly complex. Their sizes, macroscale shape (i.e., habit), mesoscale shape (i.e., aspect ratio of components) and microscale shape (i.e., surface roughness) determine optical properties and affect physical properties such as fall speeds, growth rates and aggregation efficiency. Our current understanding on the formation and evolution of ice crystals under various conditions can be considered poor. Commonly, ice crystal size and shape are related to ambient temperature and humidity, but global observational statistics on the variation of ice crystal size and particularly shape have not been available. Here we show results of a project aiming to infer ice crystal size, shape and scattering properties from a combination of MODIS measurements and POLDER-PARASOL multi-angle polarimetry. The shape retrieval procedure infers the mean aspect ratios of components of ice crystals and the mean microscale surface roughness levels, which are quantifiable parameters that mostly affect the scattering properties, in contrast to a habit. We present global statistics on the variation of ice effective radius, component aspect ratio, microscale surface roughness and scattering asymmetry parameter as a function of cloud top temperature, latitude, location, cloud type, season, etc. Generally, with increasing height, sizes decrease, roughness increases, asymmetry parameters decrease and aspect ratios increase towards unity. Some systematic differences are observed for clouds warmer and colder than the homogeneous freezing level. Uncertainties in the retrievals will be discussed. These statistics can be used as observational targets for modeling efforts and to better constrain other satellite remote sensing applications and their uncertainties.

Generalized Entropic Uncertainty Relations with Tsallis' Entropy

NASA Technical Reports Server (NTRS)

Portesi, M.; Plastino, A.

1996-01-01

A generalization of the entropic formulation of the Uncertainty Principle of Quantum Mechanics is considered with the introduction of the q-entropies recently proposed by Tsallis. The concomitant generalized measure is illustrated for the case of phase and number operators in quantum optics. Interesting results are obtained when making use of q-entropies as the basis for constructing generalized entropic uncertainty measures.

Wavelength-encoded optical psychrometer for relative humidity measurement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Montanini, Roberto

2007-02-15

In this article an optical psychrometer, in which temperature measurements are performed by means of two fiber Bragg grating sensors used as dry-bulb and wet-bulb thermometers, is introduced. The adopted design exploits both the high accuracy of psychrometric-based relative humidity measurements with acknowledged advantages of wavelength-encoded fiber optic sensing. Important metrological issues that have been addressed in the experimental work include calibration of the fiber Bragg grating temperature sensors, evaluation of response time, sensitivity, hysteresis, linearity, and accuracy. The calibration results give confidence that, with the current experimental setup, measurement of temperature can be done with an uncertainty of {+-}0.2more » deg. C and a resolution of 0.1 deg. C. A detailed uncertainty analysis is also presented in the article to investigate the effects produced by different sources of error on the combined standard uncertainty u{sub c}(U) of the relative humidity measurement, which has been estimated to be roughly within {+-}2% in the range close to saturation.« less

Wavelength-encoded optical psychrometer for relative humidity measurement.

PubMed

Montanini, Roberto

2007-02-01

In this article an optical psychrometer, in which temperature measurements are performed by means of two fiber Bragg grating sensors used as dry-bulb and wet-bulb thermometers, is introduced. The adopted design exploits both the high accuracy of psychrometric-based relative humidity measurements with acknowledged advantages of wavelength-encoded fiber optic sensing. Important metrological issues that have been addressed in the experimental work include calibration of the fiber Bragg grating temperature sensors, evaluation of response time, sensitivity, hysteresis, linearity, and accuracy. The calibration results give confidence that, with the current experimental setup, measurement of temperature can be done with an uncertainty of +/- 0.2 degrees C and a resolution of 0.1 degrees C. A detailed uncertainty analysis is also presented in the article to investigate the effects produced by different sources of error on the combined standard uncertainty uc(U) of the relative humidity measurement, which has been estimated to be roughly within +/-2% in the range close to saturation.

Absolute frequency measurement of the ? optical clock transition in ? with an uncertainty of ? using a frequency link to international atomic time

NASA Astrophysics Data System (ADS)

Baynham, Charles F. A.; Godun, Rachel M.; Jones, Jonathan M.; King, Steven A.; Nisbet-Jones, Peter B. R.; Baynes, Fred; Rolland, Antoine; Baird, Patrick E. G.; Bongs, Kai; Gill, Patrick; Margolis, Helen S.

2018-03-01

The highly forbidden ? electric octupole transition in ? is a potential candidate for a redefinition of the SI second. We present a measurement of the absolute frequency of this optical transition, performed using a frequency link to International Atomic Time to provide traceability to the SI second. The ? optical frequency standard was operated for 76% of a 25-day period, with the absolute frequency measured to be 642 121 496 772 645.14(26) Hz. The fractional uncertainty of ? is comparable to that of the best previously reported measurement, which was made by a direct comparison to local caesium primary frequency standards.

Selected highly charged ions as prospective candidates for optical clocks with quality factors larger than 1015

NASA Astrophysics Data System (ADS)

Yu, Yan-mei; Sahoo, B. K.

2018-04-01

The Ni12 +, Cu13 +, Pd12 +, and Ag13 + highly charged ions (HCIs) are proposed for making very accurate optical clocks with the fractional uncertainties below 10-19 level. These HCIs have simple atomic energy levels, clock transitions with quality factors larger than 1015, and optical magnetic-dipole (M 1 ) transitions that can be used for laser cooling and detecting quantum jumps on the clock transitions by the shelving method. To demonstrate the projected fractional uncertainties, we estimate orders of magnitude of the Zeeman, Stark, blackbody radiation, and electric quadrupole shifts of the clock transitions by performing calculations of the relevant atomic properties in the above HCIs.

Optical Characterization of Component Wear and Near-Field Plasma of the Hermes Thruster

NASA Technical Reports Server (NTRS)

Williams, George J., Jr.; Kamhawi, Hani

2015-01-01

Optical emission spectral (OES) data are presented which correlate trends in sputtered species and the near-field plasma with the Hall-Effect Rocket with Magnetic Shielding (HERMeS) thruster operating condition. The relative density of singly-ionized xenon (Xe II) is estimated using a collisional-radiative model. OES data were collected at three radial and several axial locations downstream of the thruster's exit plane. These data were deconvolved to show the structure for the near-field plasma as a function of thruster operating condition. The magnetic field is shown to have a much greater affect on plasma structure than the discharge voltage with the primary ionization/acceleration zone boundary being similar for all nominal operating voltages at constant power. OES measurement of sputtered boron shows that the HERMeS thruster is magnetically shielded across its operating envelope. Preliminary assessment of carbon sputtered from the keeper face suggest it increases significantly with operating voltage, but the uncertainty associated with these measurements is very high.

30 Doradus - Ultraviolet and optical stellar photometry

NASA Technical Reports Server (NTRS)

Hill, Jesse K.; Bohlin, Ralph C.; Cheng, Kwang-Ping; Fanelli, Michael N.; Hintzen, Paul; O'Connell, Robert W.; Roberts, Morton S.; Smith, Andrew M.; Smith, Eric P.; Stecher, Theodore P.

1993-01-01

Ultraviolet Imaging Telescope (UIT) UV magnitudes in four bands, together with optical B magnitudes, are presented for up to 314 early-type stars located in a 9.7 x 9.7 arcmin field centered on R136. The magnitudes have an rms uncertainty estimated at 0.10 mag from a comparison between the UIT magnitudes and the IUE spectra. Spectral types and E(B-V) color excesses are estimated. The mean color excesses following the two extinction curves agree well with the predictions of the two-component extinction model of Fitzpatrick and Savage (1984). However, the degree of nebular extinction is found to vary systematically by large amounts over the 30 Dor field. The minimum of nebular extinction in the central parts of the nebula suggests that dust has been expelled from this region by stellar winds. It is suggested that the form of the UV extinction curve can be understood as a consequence of the evolutionary state of the stellar population responsible for making the dust grains.

Investigations on Size Effects of Zerodur®

NASA Astrophysics Data System (ADS)

Behar-Lafenetre, S.; Cornillon, L.; Ait-Zaid, S.; Rancurel, M.

2014-06-01

Zerodur® is a well-known glass-ceramic used for optical components because of its unequalled stability under thermal environment (due to its extremely low Coefficient of Thermal Expansion). In particular it has been used since decades in Thales Alenia Space's optical payloads for space telescopes, especially for primary mirrors.The drawback of Zerodur® however is its quite low strength: 10 MPa is historically used as a rule of thumb. However, as performance of space telescopes is increasing, an optimization of the design is necessary and therefore an increase of the strength limit taken into account in the calculations.Thales Alenia Space is therefore currently investigating the so-called "size effect" on Zerodur® (see Weibull theory), under CNES funding, with the aim of re- estimating the lower bound of Zerodur® strength.For this, a complete test campaign has been defined with a high number of samples in order to reduce uncertainties. This article presents the first results obtained.

Development of probabilistic internal dosimetry computer code

NASA Astrophysics Data System (ADS)

Noh, Siwan; Kwon, Tae-Eun; Lee, Jai-Ki

2017-02-01

Internal radiation dose assessment involves biokinetic models, the corresponding parameters, measured data, and many assumptions. Every component considered in the internal dose assessment has its own uncertainty, which is propagated in the intake activity and internal dose estimates. For research or scientific purposes, and for retrospective dose reconstruction for accident scenarios occurring in workplaces having a large quantity of unsealed radionuclides, such as nuclear power plants, nuclear fuel cycle facilities, and facilities in which nuclear medicine is practiced, a quantitative uncertainty assessment of the internal dose is often required. However, no calculation tools or computer codes that incorporate all the relevant processes and their corresponding uncertainties, i.e., from the measured data to the committed dose, are available. Thus, the objective of the present study is to develop an integrated probabilistic internal-dose-assessment computer code. First, the uncertainty components in internal dosimetry are identified, and quantitative uncertainty data are collected. Then, an uncertainty database is established for each component. In order to propagate these uncertainties in an internal dose assessment, a probabilistic internal-dose-assessment system that employs the Bayesian and Monte Carlo methods. Based on the developed system, we developed a probabilistic internal-dose-assessment code by using MATLAB so as to estimate the dose distributions from the measured data with uncertainty. Using the developed code, we calculated the internal dose distribution and statistical values ( e.g. the 2.5th, 5th, median, 95th, and 97.5th percentiles) for three sample scenarios. On the basis of the distributions, we performed a sensitivity analysis to determine the influence of each component on the resulting dose in order to identify the major component of the uncertainty in a bioassay. The results of this study can be applied to various situations. In cases of severe internal exposure, the causation probability of a deterministic health effect can be derived from the dose distribution, and a high statistical value ( e.g., the 95th percentile of the distribution) can be used to determine the appropriate intervention. The distribution-based sensitivity analysis can also be used to quantify the contribution of each factor to the dose uncertainty, which is essential information for reducing and optimizing the uncertainty in the internal dose assessment. Therefore, the present study can contribute to retrospective dose assessment for accidental internal exposure scenarios, as well as to internal dose monitoring optimization and uncertainty reduction.

Quantifying catchment water balances and their uncertainties by expert elicitation

NASA Astrophysics Data System (ADS)

Sebok, Eva; Refsgaard, Jens Christian; Warmink, Jord J.; Stisen, Simon; Høgh Jensen, Karsten

2017-04-01

The increasing demand on water resources necessitates a more responsible and sustainable water management requiring a thorough understanding of hydrological processes both on small scale and on catchment scale. On catchment scale, the characterization of hydrological processes is often carried out by calculating a water balance based on the principle of mass conservation in hydrological fluxes. Assuming a perfect water balance closure and estimating one of these fluxes as a residual of the water balance is a common practice although this estimate will contain uncertainties related to uncertainties in the other components. Water balance closure on the catchment scale is also an issue in Denmark, thus, it was one of the research objectives of the HOBE hydrological observatory, that has been collecting data in the Skjern river catchment since 2008. Water balance components in the 1050 km2 Ahlergaarde catchment and the nested 120 km2 Holtum catchment, located in the glacial outwash plan of the Skjern catchment, were estimated using a multitude of methods. As the collected data enables the complex assessment of uncertainty of both the individual water balance components and catchment-scale water balances, the expert elicitation approach was chosen to integrate the results of the hydrological observatory. This approach relies on the subjective opinion of experts whose available knowledge and experience about the subject allows to integrate complex information from multiple sources. In this study 35 experts were involved in a multi-step elicitation process with the aim of (1) eliciting average annual values of water balance components for two nested catchments and quantifying the contribution of different sources of uncertainties to the total uncertainty in these average annual estimates; (2) calculating water balances for two catchments by reaching consensus among experts interacting in form of group discussions. To address the complex problem of water balance closure, the water balance was separated into five components: precipitation, evapotranspiration, surface runoff, recharge and subsurface outflow. During the study, experts first participated in individual interviews where they gave their opinion on the probability distribution of their water balance component of interest. The average annual values and uncertainty of water balance components and catchment-scale water balances were obtained at a later stage by reaching consensus during group discussions. The obtained water balance errors for the Ahlergaarde catchment and the Holtum catchment were -5 and -62 mm/yr, respectively, with an uncertainty of 66 and 86 mm/yr, respectively. As an advantage of the expert elicitation, drawing on the intuitive experience and capabilities of experts to assess complex, site-specific problems, not only the uncertainty of the water balance error was quantified, but the uncertainty of individual water balance components as well.

Optical and Radar Measurements of the Meteor Speed Distribution

NASA Technical Reports Server (NTRS)

Moorhead, A. V.; Brown, P. G.; Campbell-Brown, M. D.; Kingery, A.; Cooke, W. J.

2016-01-01

The observed meteor speed distribution provides information on the underlying orbital distribution of Earth-intersecting meteoroids. It also affects spacecraft risk assessments; faster meteors do greater damage to spacecraft surfaces. Although radar meteor networks have measured the meteor speed distribution numerous times, the shape of the de-biased speed distribution varies widely from study to study. Optical characterizations of the meteoroid speed distribution are fewer in number, and in some cases the original data is no longer available. Finally, the level of uncertainty in these speed distributions is rarely addressed. In this work, we present the optical meteor speed distribution extracted from the NASA and SOMN allsky networks [1, 2] and from the Canadian Automated Meteor Observatory (CAMO) [3]. We also revisit the radar meteor speed distribution observed by the Canadian Meteor Orbit Radar (CMOR) [4]. Together, these data span the range of meteoroid sizes that can pose a threat to spacecraft. In all cases, we present our bias corrections and incorporate the uncertainty in these corrections into uncertainties in our de-biased speed distribution. Finally, we compare the optical and radar meteor speed distributions and discuss the implications for meteoroid environment models.

A Precise Physical Orbit for the M-dwarf Binary Gliese 268

NASA Astrophysics Data System (ADS)

Barry, R. K.; Demory, B.-O.; Ségransan, D.; Forveille, T.; Danchi, W. C.; Di Folco, E.; Queloz, D.; Spooner, H. R.; Torres, G.; Traub, W. A.; Delfosse, X.; Mayor, M.; Perrier, C.; Udry, S.

2012-11-01

We report high-precision interferometric and radial velocity (RV) observations of the M-dwarf binary Gl 268. Combining measurements conducted using the IOTA interferometer and the ELODIE and Harvard Center for Astrophysics RV instruments leads to a mass of 0.22596 ± 0.00084 M ⊙ for component A and 0.19230 ± 0.00071 M ⊙ for component B. The system parallax as determined by these observations is 0.1560 ± 0.0030 arcsec—a measurement with 1.9% uncertainty in excellent agreement with Hipparcos (0.1572 ± 0.0033). The absolute H-band magnitudes of the component stars are not well constrained by these measurements; however, we can place an approximate upper limit of 7.95 and 8.1 for Gl 268A and B, respectively. We test these physical parameters against the predictions of theoretical models that combine stellar evolution with high fidelity, non-gray atmospheric models. Measured and predicted values are compatible within 2σ. These results are among the most precise masses measured for visual binaries and compete with the best adaptive optics and eclipsing binary results.

Variability of ICA decomposition may impact EEG signals when used to remove eyeblink artifacts

PubMed Central

PONTIFEX, MATTHEW B.; GWIZDALA, KATHRYN L.; PARKS, ANDREW C.; BILLINGER, MARTIN; BRUNNER, CLEMENS

2017-01-01

Despite the growing use of independent component analysis (ICA) algorithms for isolating and removing eyeblink-related activity from EEG data, we have limited understanding of how variability associated with ICA uncertainty may be influencing the reconstructed EEG signal after removing the eyeblink artifact components. To characterize the magnitude of this ICA uncertainty and to understand the extent to which it may influence findings within ERP and EEG investigations, ICA decompositions of EEG data from 32 college-aged young adults were repeated 30 times for three popular ICA algorithms. Following each decomposition, eyeblink components were identified and removed. The remaining components were back-projected, and the resulting clean EEG data were further used to analyze ERPs. Findings revealed that ICA uncertainty results in variation in P3 amplitude as well as variation across all EEG sampling points, but differs across ICA algorithms as a function of the spatial location of the EEG channel. This investigation highlights the potential of ICA uncertainty to introduce additional sources of variance when the data are back-projected without artifact components. Careful selection of ICA algorithms and parameters can reduce the extent to which ICA uncertainty may introduce an additional source of variance within ERP/EEG studies. PMID:28026876

Optical components damage parameters database system

NASA Astrophysics Data System (ADS)

Tao, Yizheng; Li, Xinglan; Jin, Yuquan; Xie, Dongmei; Tang, Dingyong

2012-10-01

Optical component is the key to large-scale laser device developed by one of its load capacity is directly related to the device output capacity indicators, load capacity depends on many factors. Through the optical components will damage parameters database load capacity factors of various digital, information technology, for the load capacity of optical components to provide a scientific basis for data support; use of business processes and model-driven approach, the establishment of component damage parameter information model and database systems, system application results that meet the injury test optical components business processes and data management requirements of damage parameters, component parameters of flexible, configurable system is simple, easy to use, improve the efficiency of the optical component damage test.

Planck 2015 results. III. LFI systematic uncertainties

NASA Astrophysics Data System (ADS)

Planck Collaboration; Ade, P. A. R.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Bartolo, N.; Basak, S.; Battaglia, P.; Battaner, E.; Benabed, K.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bonaldi, A.; Bonavera, L.; Bond, J. R.; Borrill, J.; Burigana, C.; Butler, R. C.; Calabrese, E.; Catalano, A.; Christensen, P. R.; Colombo, L. P. L.; Cruz, M.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Dickinson, C.; Diego, J. M.; Doré, O.; Ducout, A.; Dupac, X.; Elsner, F.; Enßlin, T. A.; Eriksen, H. K.; Finelli, F.; Frailis, M.; Franceschet, C.; Franceschi, E.; Galeotta, S.; Galli, S.; Ganga, K.; Ghosh, T.; Giard, M.; Giraud-Héraud, Y.; Gjerløw, E.; González-Nuevo, J.; Górski, K. M.; Gregorio, A.; Gruppuso, A.; Hansen, F. K.; Harrison, D. L.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Hornstrup, A.; Hovest, W.; Huffenberger, K. M.; Hurier, G.; Jaffe, A. H.; Jaffe, T. R.; Keihänen, E.; Keskitalo, R.; Kiiveri, K.; Kisner, T. S.; Knoche, J.; Krachmalnicoff, N.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Leahy, J. P.; Leonardi, R.; Levrier, F.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; Lindholm, V.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maffei, B.; Maggio, G.; Maino, D.; Mandolesi, N.; Mangilli, A.; Maris, M.; Martin, P. G.; Martínez-González, E.; Masi, S.; Matarrese, S.; Meinhold, P. R.; Mennella, A.; Migliaccio, M.; Mitra, S.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, J. A.; Nati, F.; Natoli, P.; Noviello, F.; Paci, F.; Pagano, L.; Pajot, F.; Paoletti, D.; Partridge, B.; Pasian, F.; Pearson, T. J.; Perdereau, O.; Pettorino, V.; Piacentini, F.; Pointecouteau, E.; Polenta, G.; Pratt, G. W.; Puget, J.-L.; Rachen, J. P.; Reinecke, M.; Remazeilles, M.; Renzi, A.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rossetti, M.; Roudier, G.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Santos, D.; Savelainen, M.; Scott, D.; Stolyarov, V.; Stompor, R.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Tavagnacco, D.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vassallo, T.; Vielva, P.; Villa, F.; Wade, L. A.; Wandelt, B. D.; Watson, R.; Wehus, I. K.; Yvon, D.; Zacchei, A.; Zibin, J. P.; Zonca, A.

2016-09-01

We present the current accounting of systematic effect uncertainties for the Low Frequency Instrument (LFI) that are relevant to the 2015 release of the Planck cosmological results, showing the robustness and consistency of our data set, especially for polarization analysis. We use two complementary approaches: (I) simulations based on measured data and physical models of the known systematic effects; and (II) analysis of difference maps containing the same sky signal ("null-maps"). The LFI temperature data are limited by instrumental noise. At large angular scales the systematic effects are below the cosmic microwave background (CMB) temperature power spectrum by several orders of magnitude. In polarization the systematic uncertainties are dominated by calibration uncertainties and compete with the CMB E-modes in the multipole range 10-20. Based on our model of all known systematic effects, we show that these effects introduce a slight bias of around 0.2σ on the reionization optical depth derived from the 70GHz EE spectrum using the 30 and 353GHz channels as foreground templates. At 30GHz the systematic effects are smaller than the Galactic foreground at all scales in temperature and polarization, which allows us to consider this channel as a reliable template of synchrotron emission. We assess the residual uncertainties due to LFI effects on CMB maps and power spectra after component separation and show that these effects are smaller than the CMB amplitude at all scales. We also assess the impact on non-Gaussianity studies and find it to be negligible. Some residuals still appear in null maps from particular sky survey pairs, particularly at 30 GHz, suggesting possible straylight contamination due to an imperfect knowledge of the beam far sidelobes.

Planck 2015 results: III. LFI systematic uncertainties

DOE PAGES

Ade, P. A. R.; Aumont, J.; Baccigalupi, C.; ...

2016-09-20

In this paper, we present the current accounting of systematic effect uncertainties for the Low Frequency Instrument (LFI) that are relevant to the 2015 release of the Planck cosmological results, showing the robustness and consistency of our data set, especially for polarization analysis. We use two complementary approaches: (i) simulations based on measured data and physical models of the known systematic effects; and (ii) analysis of difference maps containing the same sky signal (“null-maps”). The LFI temperature data are limited by instrumental noise. At large angular scales the systematic effects are below the cosmic microwave background (CMB) temperature power spectrummore » by several orders of magnitude. In polarization the systematic uncertainties are dominated by calibration uncertainties and compete with the CMB E-modes in the multipole range 10–20. Based on our model of all known systematic effects, we show that these effects introduce a slight bias of around 0.2σ on the reionization optical depth derived from the 70GHz EE spectrum using the 30 and 353GHz channels as foreground templates. At 30GHz the systematic effects are smaller than the Galactic foreground at all scales in temperature and polarization, which allows us to consider this channel as a reliable template of synchrotron emission. We assess the residual uncertainties due to LFI effects on CMB maps and power spectra after component separation and show that these effects are smaller than the CMB amplitude at all scales. We also assess the impact on non-Gaussianity studies and find it to be negligible. Finally, some residuals still appear in null maps from particular sky survey pairs, particularly at 30 GHz, suggesting possible straylight contamination due to an imperfect knowledge of the beam far sidelobes.« less

Planck 2015 results: III. LFI systematic uncertainties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ade, P. A. R.; Aumont, J.; Baccigalupi, C.

In this paper, we present the current accounting of systematic effect uncertainties for the Low Frequency Instrument (LFI) that are relevant to the 2015 release of the Planck cosmological results, showing the robustness and consistency of our data set, especially for polarization analysis. We use two complementary approaches: (i) simulations based on measured data and physical models of the known systematic effects; and (ii) analysis of difference maps containing the same sky signal (“null-maps”). The LFI temperature data are limited by instrumental noise. At large angular scales the systematic effects are below the cosmic microwave background (CMB) temperature power spectrummore » by several orders of magnitude. In polarization the systematic uncertainties are dominated by calibration uncertainties and compete with the CMB E-modes in the multipole range 10–20. Based on our model of all known systematic effects, we show that these effects introduce a slight bias of around 0.2σ on the reionization optical depth derived from the 70GHz EE spectrum using the 30 and 353GHz channels as foreground templates. At 30GHz the systematic effects are smaller than the Galactic foreground at all scales in temperature and polarization, which allows us to consider this channel as a reliable template of synchrotron emission. We assess the residual uncertainties due to LFI effects on CMB maps and power spectra after component separation and show that these effects are smaller than the CMB amplitude at all scales. We also assess the impact on non-Gaussianity studies and find it to be negligible. Finally, some residuals still appear in null maps from particular sky survey pairs, particularly at 30 GHz, suggesting possible straylight contamination due to an imperfect knowledge of the beam far sidelobes.« less

Detailed Analysis of the Asteroid Pair (6070) Rheinland and (54827) 2001 NQ8

NASA Astrophysics Data System (ADS)

Vokrouhlický, David; Pravec, Petr; Ďurech, Josef; Hornoch, Kamil; Kušnirák, Peter; Galád, Adrián; Vraštil, Jan; Kučáková, Hana; Pollock, Joseph T.; Ortiz, Jose Luis; Morales, Nicolas; Gaftonyuk, Ninel M.; Pray, Donald P.; Krugly, Yurij N.; Inasaridze, Raguli Ya.; Ayvazian, Vova R.; Molotov, Igor E.; Colazo, Carlos A.

2017-06-01

The existence of asteroid pairs, two bodies on similar heliocentric orbits, reveals an ongoing process of rotational fission among asteroids. This newly found class of objects has not been studied in detail yet. Here we choose asteroids (6070) Rheinland and (54827) 2001 NQ8, the most suitable pair for an in-depth analysis. First, we use available optical photometry to determine their rotational state and convex shapes. Rotational pole of Rheinland is very near the south ecliptic pole with a latitude uncertainty of about 10°. There are two equivalent solutions for the pole of 2001 NQ8, either (72°, -49°) or (242°, -46°) (ecliptic longitude and latitude). In both cases, the longitude values have about 10° uncertainty and the latitude values have about 15° uncertainty (both 3σ uncertainties). The sidereal rotation period of 2001 NQ8 is 5.877186 ± 0.000002 hr. Second, we construct a precise numerical integrator to determine the past state vectors of the pair’s components, namely their heliocentric positions and velocities, and orientation of their spin vectors. Using this new tool, we investigate the origin of the (6070) Rheinland and (54827) 2001 NQ8 pair. We find a formal age solution of 16.34 ± 0.04 kyr. This includes effects of the most massive objects in the asteroid belt (Ceres, Pallas, and Vesta), but the unaccounted gravitational perturbations from other asteroids may imply that the realistic age uncertainty is slightly larger than its formal value. Analyzing results from our numerical simulation to 250 kya, we argue against a possibility that this pair would allow an older age. Initial spin vectors of the two asteroids, at the moment of their separation, were not collinear, but tilted by 38^\\circ +/- 12^\\circ .

Optoelectronics components and technology for optical networking in China: recent progress and future trends

NASA Astrophysics Data System (ADS)

Jiang, Shan; Liu, Shuihua

2004-04-01

Current optical communication systems are more and more relying on the advanced opto-electronic components. A series of revolutionary optical and optoelectronics components technology accounts for the fast progress and field deployment of high-capacity telecommunication and data-transmission systems. Since 1990s, the optical communication industry in China entered a high-speed development period and its wide deployment had already established the solid base for China information infrastructure. In this presentation, the main progress of optoelectronics components and technology in China are reviewed, which includes semiconductor laser diode/photo receiver, fiber optical amplifier, DWDM multiplexer/de-multiplexer, dispersion compensation components and all optical network node components, such as optical switch, OADM, tunable optical filters and variable optical attenuators, etc. Integration discrete components into monolithic/hybrid platform component is an inevitable choice for the consideration of performance, mass production and cost reduction. The current status and the future trends of OEIC and PIC components technology in China will also be discuss mainly on the monolithic integration DFB LD + EA modulator, and planar light-wave circuit (PLC) technology, etc.

Methods for globally treating silica optics to reduce optical damage

DOEpatents

Miller, Philip Edward; Suratwala, Tayyab Ishaq; Bude, Jeffrey Devin; Shen, Nan; Steele, William Augustus; Laurence, Ted Alfred; Feit, Michael Dennis; Wong, Lana Louie

2012-11-20

A method for preventing damage caused by high intensity light sources to optical components includes annealing the optical component for a predetermined period. Another method includes etching the optical component in an etchant including fluoride and bi-fluoride ions. The method also includes ultrasonically agitating the etching solution during the process followed by rinsing of the optical component in a rinse bath.

The Effects of an Absorbing Smoke Layer on MODIS Marine Boundary Layer Cloud Optical Property Retrievals and Radiative Forcing

NASA Technical Reports Server (NTRS)

Meyer, Kerry; Platnick, Steven

2012-01-01

Clouds, aerosols, and their interactions are widely considered to be key uncertainty components in our current understanding of the Earth's atmosphere and radiation budget. The work presented here is focused on the quasi-permanent marine boundary layer . (MBL) clouds off the southern Atlantic coast of Africa and the effects on MODIS cloud optical property retrievals (MOD06) of an overlying absorbing smoke layer. During much of August and September, a persistent smoke layer resides over this region, produced from extensive biomass burning throughout the southern African savanna. The resulting absorption, which increases with decreasing wavelength, potentially introduces biases into the MODIS cloud optical property retrievals of the underlying MBL clouds. This effect is more pronounced in the cloud optical thickness retrievals, which over ocean are derived from the wavelength channel centered near 0.86 micron (effective particle size retrievals are derived from the longer-wavelength near-IR channels at 1.6, 2.1, and 3.7 microns). Here, the spatial distributions of the scalar statistics of both the cloud and aerosol layers are first determined from the CALIOP 5 km layer products. Next, the MOD06 look-up tables (LUTs) are adjusted by inserting an absorbing smoke layer of varying optical thickness over the cloud. Retrievals are subsequently performed for a subset of MODIS pixels collocated with the CALIOP ground track, using smoke optical thickness from the CALIOP 5km aerosol layer product to select the appropriate LUT. The resulting differences in cloud optical property retrievals due to the inclusion of the smoke layer in the LUTs will be examined. In addition, the direct radiative forcing of this smoke layer will be investigated from the perspective of the cloud optical property retrieval differences.

Uncertainty in Reference and Information Service

ERIC Educational Resources Information Center

VanScoy, Amy

2015-01-01

Introduction: Uncertainty is understood as an important component of the information seeking process, but it has not been explored as a component of reference and information service. Method: Interpretative phenomenological analysis was used to examine the practitioner perspective of reference and information service for eight academic research…

A clock network for geodesy and fundamental science

PubMed Central

Lisdat, C.; Grosche, G.; Quintin, N.; Shi, C.; Raupach, S.M.F.; Grebing, C.; Nicolodi, D.; Stefani, F.; Al-Masoudi, A.; Dörscher, S.; Häfner, S.; Robyr, J.-L.; Chiodo, N.; Bilicki, S.; Bookjans, E.; Koczwara, A.; Koke, S.; Kuhl, A.; Wiotte, F.; Meynadier, F.; Camisard, E.; Abgrall, M.; Lours, M.; Legero, T.; Schnatz, H.; Sterr, U.; Denker, H.; Chardonnet, C.; Le Coq, Y.; Santarelli, G.; Amy-Klein, A.; Le Targat, R.; Lodewyck, J.; Lopez, O; Pottie, P.-E.

2016-01-01

Leveraging the unrivalled performance of optical clocks as key tools for geo-science, for astronomy and for fundamental physics beyond the standard model requires comparing the frequency of distant optical clocks faithfully. Here, we report on the comparison and agreement of two strontium optical clocks at an uncertainty of 5 × 10−17 via a newly established phase-coherent frequency link connecting Paris and Braunschweig using 1,415 km of telecom fibre. The remote comparison is limited only by the instability and uncertainty of the strontium lattice clocks themselves, with negligible contributions from the optical frequency transfer. A fractional precision of 3 × 10−17 is reached after only 1,000 s averaging time, which is already 10 times better and more than four orders of magnitude faster than any previous long-distance clock comparison. The capability of performing high resolution international clock comparisons paves the way for a redefinition of the unit of time and an all-optical dissemination of the SI-second. PMID:27503795

A clock network for geodesy and fundamental science.

PubMed

Lisdat, C; Grosche, G; Quintin, N; Shi, C; Raupach, S M F; Grebing, C; Nicolodi, D; Stefani, F; Al-Masoudi, A; Dörscher, S; Häfner, S; Robyr, J-L; Chiodo, N; Bilicki, S; Bookjans, E; Koczwara, A; Koke, S; Kuhl, A; Wiotte, F; Meynadier, F; Camisard, E; Abgrall, M; Lours, M; Legero, T; Schnatz, H; Sterr, U; Denker, H; Chardonnet, C; Le Coq, Y; Santarelli, G; Amy-Klein, A; Le Targat, R; Lodewyck, J; Lopez, O; Pottie, P-E

2016-08-09

Leveraging the unrivalled performance of optical clocks as key tools for geo-science, for astronomy and for fundamental physics beyond the standard model requires comparing the frequency of distant optical clocks faithfully. Here, we report on the comparison and agreement of two strontium optical clocks at an uncertainty of 5 × 10(-17) via a newly established phase-coherent frequency link connecting Paris and Braunschweig using 1,415 km of telecom fibre. The remote comparison is limited only by the instability and uncertainty of the strontium lattice clocks themselves, with negligible contributions from the optical frequency transfer. A fractional precision of 3 × 10(-17) is reached after only 1,000 s averaging time, which is already 10 times better and more than four orders of magnitude faster than any previous long-distance clock comparison. The capability of performing high resolution international clock comparisons paves the way for a redefinition of the unit of time and an all-optical dissemination of the SI-second.

Method for the continuous processing of hermetic fiber optic components and the resultant fiber optic-to-metal components

DOEpatents

Kramer, D.P.

1994-08-09

Hermetic fiber optic-to-metal components and method for making hermetic fiber optic-to-metal components by assembling and fixturing elements comprising a metal shell, a glass preform, and a metal-coated fiber optic into desired relative positions and then sealing said fixtured elements preferably using a continuous heating process is disclosed. The resultant hermetic fiber optic-to-metal components exhibit high hermeticity and durability despite the large differences in thermal coefficients of expansion among the various elements. 3 figs.

A review of recent work in sub-nanometre displacement measurement using optical and X-ray interferometry.

PubMed

Peggs, G N; Yacoot, A

2002-05-15

This paper reviews recent work in the field of displacement measurement using optical and X-ray interferometry at the sub-nanometre level of accuracy. The major sources of uncertainty in optical interferometry are discussed and a selection of recent designs of ultra-precise, optical-interferometer-based, displacement measuring transducers presented. The use of X-ray interferometry and its combination with optical interferometry is discussed.

Asteroid approach covariance analysis for the Clementine mission

NASA Technical Reports Server (NTRS)

Ionasescu, Rodica; Sonnabend, David

1993-01-01

The Clementine mission is designed to test Strategic Defense Initiative Organization (SDIO) technology, the Brilliant Pebbles and Brilliant Eyes sensors, by mapping the moon surface and flying by the asteroid Geographos. The capability of two of the instruments available on board the spacecraft, the lidar (laser radar) and the UV/Visible camera is used in the covariance analysis to obtain the spacecraft delivery uncertainties at the asteroid. These uncertainties are due primarily to asteroid ephemeris uncertainties. On board optical navigation reduces the uncertainty in the knowledge of the spacecraft position in the direction perpendicular to the incoming asymptote to a one-sigma value of under 1 km, at the closest approach distance of 100 km. The uncertainty in the knowledge of the encounter time is about 0.1 seconds for a flyby velocity of 10.85 km/s. The magnitude of these uncertainties is due largely to Center Finding Errors (CFE). These systematic errors represent the accuracy expected in locating the center of the asteroid in the optical navigation images, in the absence of a topographic model for the asteroid. The direction of the incoming asymptote cannot be estimated accurately until minutes before the asteroid flyby, and correcting for it would require autonomous navigation. Orbit determination errors dominate over maneuver execution errors, and the final delivery accuracy attained is basically the orbit determination uncertainty before the final maneuver.

Comparison of Carbon Dioxide Airborne Measurement over Land and Ocean using 2-μm Double-Pulse Integrated Path Differential Absorption Lidar

NASA Astrophysics Data System (ADS)

Refaat, T. F.; Singh, U. N.; Petros, M.; Yu, J.; Remus, R.; Ismail, S.

2017-12-01

An airborne Integrated Path Differential Absorption (IPDA) lidar has been developed and validated at NASA Langley Research Center for atmospheric carbon dioxide column measurements. The instrument consists of a tunable, high-energy 2-μm double pulse laser transmitter and 0.4 m telescope receiver coupled to an InGaAs pin detection system. The instrument was validated for carbon dioxide (CO2) measurements from ground and airborne platforms, using a movable lidar trailer and the NASA B-200 aircraft. Airborne validation was conducted over the ocean by comparing the IPDA CO2 optical depth measurement to optical depth model derived using NOAA airborne CO2 air-sampling. Another airborne validation was conducted over land vegetation by comparing the IPDA measurement to a model derived using on-board in-situ measurements using an absolute, non-dispersive infrared gas analyzer (LiCor 840A). IPDA range measurements were also compared to rangefinder and Global Positioning System (GPS) records during ground and airborne validation, respectively. Range measurements from the ground indicated a 0.93 m IPDA range measurement uncertainty, which is limited by the transmitted laser pulse and detection system properties. This uncertainty increased to 2.80 and 7.40 m over ocean and land, due to fluctuations in ocean surface and ground elevations, respectively. IPDA CO2 differential optical depth measurements agree with both models. Consistent CO2 optical depth biases were well correlated with the digitizer full scale input range settings. CO2 optical depth measurements over ocean from 3.1 and 6.1 km altitudes indicated 0.95% and 0.83% uncertainty, respectively, using 10 second (100 shots) averaging. Using the same averaging 0.40% uncertainty was observed over land, from 3.4 km altitude, due to higher surface reflectivity, which increases the return signal power and enhances the signal-to-noise ratio. However, less uncertainty is observed at higher altitudes due to reduced signal shot noise, indicating that detection system noise-equivalent-power dominates the error. These results show that the IPDA technique is well suited for space-based platforms, which includes larger column content integration that enhances the measurement sensitivity.

Traceable X,Y self-calibration at single nm level of an optical microscope used for coherence scanning interferometry

NASA Astrophysics Data System (ADS)

Ekberg, Peter; Mattsson, Lars

2018-03-01

Coherence scanning interferometry used in optical profilers are typically good for Z-calibration at nm-levels, but the X,Y accuracy is often left without further notice than typical resolution limits of the optics, i.e. of the order of ~1 µm. For the calibration of metrology tools we rely on traceable artefacts, e.g. gauge blocks for traditional coordinate measurement machines, and lithographically mask made artefacts for microscope calibrations. In situations where the repeatability and accuracy of the measurement tool is much better than the uncertainty of the traceable artefact, we are bound to specify the uncertainty based on the calibration artefact rather than on the measurement tool. This is a big drawback as the specified uncertainty of a calibrated measurement may shrink the available manufacturing tolerance. To improve the uncertainty in X,Y we can use self-calibration. Then, we do not need to know anything more than that the artefact contains a pattern with some nominal grid. This also gives the opportunity to manufacture the artefact in-house, rather than buying a calibrated and expensive artefact. The self-calibration approach we present here is based on an iteration algorithm, rather than the traditional mathematical inversion, and it leads to much more relaxed constrains on the input measurements. In this paper we show how the X,Y errors, primarily optical distortions, within the field of view (FOV) of an optical coherence scanning interferometry microscope, can be reduced with a large factor. By self-calibration we achieve an X,Y consistency in the 175  ×  175 µm2 FOV of ~2.3 nm (1σ) using the 50×  objective. Besides the calibrated coordinate X,Y system of the microscope we also receive, as a bonus, the absolute positions of the pattern in the artefact with a combined uncertainty of 6 nm (1σ) by relying on a traceable 1D linear measurement of a twin artefact at NIST.

A broadband chip-scale optical frequency synthesizer at 2.7 × 10−16 relative uncertainty

PubMed Central

Huang, Shu-Wei; Yang, Jinghui; Yu, Mingbin; McGuyer, Bart H.; Kwong, Dim-Lee; Zelevinsky, Tanya; Wong, Chee Wei

2016-01-01

Optical frequency combs—coherent light sources that connect optical frequencies with microwave oscillations—have become the enabling tool for precision spectroscopy, optical clockwork, and attosecond physics over the past decades. Current benchmark systems are self-referenced femtosecond mode-locked lasers, but Kerr nonlinear dynamics in high-Q solid-state microresonators has recently demonstrated promising features as alternative platforms. The advance not only fosters studies of chip-scale frequency metrology but also extends the realm of optical frequency combs. We report the full stabilization of chip-scale optical frequency combs. The microcomb’s two degrees of freedom, one of the comb lines and the native 18-GHz comb spacing, are simultaneously phase-locked to known optical and microwave references. Active comb spacing stabilization improves long-term stability by six orders of magnitude, reaching a record instrument-limited residual instability of 3.6mHz/τ. Comparing 46 nitride frequency comb lines with a fiber laser frequency comb, we demonstrate the unprecedented microcomb tooth-to-tooth relative frequency uncertainty down to 50 mHz and 2.7 × 10−16, heralding novel solid-state applications in precision spectroscopy, coherent communications, and astronomical spectrography. PMID:27152341

The research on surface characteristics of optical lens by 3D printing technique and precise diamond turning technique

NASA Astrophysics Data System (ADS)

Huang, Chien-Yao; Chang, Chun-Ming; Ho, Cheng-Fong; Lee, Tai-Wen; Lin, Ping-Hung; Hsu, Wei-Yao

2017-06-01

The advantage of 3D printing technique is flexible in design and fabrication. Using 3D printing technique, the traditional manufacturing limitations are not considered. The optical lens is the key component in an optical system. The traditional process to manufacture optical plastic lens is injection molding. However injection molding is only suitable for plastics lens, it cannot fabricate optical and mechanical components at same time. The assembly error of optical system can be reduced effectively with fabricating optical and mechanical components at same time. The process of printing optical and mechanical components simultaneously is proposed in previous papers, but the optical surface of printing components is not transparent. If we increase the transmittance of the optical surface, the printing components which fabricated by 3D printing process could be high transmission. Therefore, precise diamond turning technique has been used to turning the surface of 3D printing optical lens in this paper. The precise diamond turning techniques could process surfaces of components to meet the requirements of optical system. A 3D printing machine, Stratasys Connex 500, and a precise diamond turning machine, Precitech Freeform705XG, have been used in this paper, respectively. The dimension, roughness, transmission and printing types of 3D printing components have been discussed in this paper. After turning and polishing process, the roughness of 3D printing component is below 0.05 μm and the transmittance increase above 80 %. This optical module can be used in hand-held telescope and other system which need lens and special mechanical structure fabricated simultaneously.

First international comparison of fountain primary frequency standards via a long distance optical fiber link

NASA Astrophysics Data System (ADS)

Guéna, J.; Weyers, S.; Abgrall, M.; Grebing, C.; Gerginov, V.; Rosenbusch, P.; Bize, S.; Lipphardt, B.; Denker, H.; Quintin, N.; Raupach, S. M. F.; Nicolodi, D.; Stefani, F.; Chiodo, N.; Koke, S.; Kuhl, A.; Wiotte, F.; Meynadier, F.; Camisard, E.; Chardonnet, C.; Le Coq, Y.; Lours, M.; Santarelli, G.; Amy-Klein, A.; Le Targat, R.; Lopez, O.; Pottie, P. E.; Grosche, G.

2017-06-01

We report on the first comparison of distant caesium fountain primary frequency standards (PFSs) via an optical fiber link. The 1415 km long optical link connects two PFSs at LNE-SYRTE (Laboratoire National de métrologie et d’Essais—SYstème de Références Temps-Espace) in Paris (France) with two at PTB (Physikalisch-Technische Bundesanstalt) in Braunschweig (Germany). For a long time, these PFSs have been major contributors to accuracy of the International Atomic Time (TAI), with stated accuracies of around 3× {{10}-16} . They have also been the references for a number of absolute measurements of clock transition frequencies in various optical frequency standards in view of a future redefinition of the second. The phase coherent optical frequency transfer via a stabilized telecom fiber link enables far better resolution than any other means of frequency transfer based on satellite links. The agreement for each pair of distant fountains compared is well within the combined uncertainty of a few 10-16 for all the comparisons, which fully supports the stated PFSs’ uncertainties. The comparison also includes a rubidium fountain frequency standard participating in the steering of TAI and enables a new absolute determination of the 87Rb ground state hyperfine transition frequency with an uncertainty of 3.1× {{10}-16} . This paper is dedicated to the memory of André Clairon, who passed away on 24 December 2015, for his pioneering and long-lasting efforts in atomic fountains. He also pioneered optical links from as early as 1997.

Comparison of Aerosol Classification Results from Airborne High Spectral Resolution Lidar (HSRL) Measurements and the Calipso Vertical Feature Mask

NASA Technical Reports Server (NTRS)

Burton, S. P.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Rogers, R. R.; Obland, M. D.; Butler, C. F.; Cook, A. L.; Harper, D. B.; Froyd, K. D.;

Determining an empirical estimate of the tracking inconsistency component for true astrometric uncertainties

NASA Astrophysics Data System (ADS)

Ramanjooloo, Yudish; Tholen, David J.; Fohring, Dora; Claytor, Zach; Hung, Denise

2017-10-01

The asteroid community is moving towards the implementation of a new astrometric reporting format. This new format will finally include of complementary astrometric uncertainties in the reported observations. The availability of uncertainties will allow ephemeris predictions and orbit solutions to be constrained with greater reliability, thereby improving the efficiency of the community's follow-up and recovery efforts.Our current uncertainty model involves our uncertainties in centroiding on the trailed stars and asteroid and the uncertainty due to the astrometric solution. The accuracy of our astrometric measurements are reliant on how well we can minimise the offset between the spatial and temporal centroids of the stars and the asteroid. This offset is currently unmodelled and can be caused by variations in the cloud transparency, the seeing and tracking inconsistencies. The magnitude zero point of the image, which is affected by fluctuating weather conditions and the catalog bias in the photometric magnitudes, can serve as an indicator of the presence and thickness of clouds. Through comparison of the astrometric uncertainties to the orbit solution residuals, it was apparent that a component of the error analysis remained unaccounted for, as a result of cloud coverage and thickness, telescope tracking inconsistencies and variable seeing. This work will attempt to quantify the tracking inconsistency component. We have acquired a rich dataset with the University of Hawaii 2.24 metre telescope (UH-88 inch) that is well positioned to construct an empirical estimate of the tracking inconsistency component. This work is funded by NASA grant NXX13AI64G.

PROBING X-RAY ABSORPTION AND OPTICAL EXTINCTION IN THE INTERSTELLAR MEDIUM USING CHANDRA OBSERVATIONS OF SUPERNOVA REMNANTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Foight, Dillon R.; Slane, Patrick O.; Güver, Tolga

We present a comprehensive study of interstellar X-ray extinction using the extensive Chandra supernova remnant (SNR) archive and use our results to refine the empirical relation between the hydrogen column density and optical extinction. In our analysis, we make use of the large, uniform data sample to assess various systematic uncertainties in the measurement of the interstellar X-ray absorption. Specifically, we address systematic uncertainties that originate from (i) the emission models used to fit SNR spectra; (ii) the spatial variations within individual remnants; (iii) the physical conditions of the remnant such as composition, temperature, and non-equilibrium regions; and (iv) themore » model used for the absorption of X-rays in the interstellar medium. Using a Bayesian framework to quantify these systematic uncertainties, and combining the resulting hydrogen column density measurements with the measurements of optical extinction toward the same remnants, we find the empirical relation N {sub H} = (2.87 ± 0.12) × 10{sup 21} A {sub V} cm{sup 2}, which is significantly higher than the previous measurements.« less

Quantifying sampling noise and parametric uncertainty in atomistic-to-continuum simulations using surrogate models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Salloum, Maher N.; Sargsyan, Khachik; Jones, Reese E.

2015-08-11

We present a methodology to assess the predictive fidelity of multiscale simulations by incorporating uncertainty in the information exchanged between the components of an atomistic-to-continuum simulation. We account for both the uncertainty due to finite sampling in molecular dynamics (MD) simulations and the uncertainty in the physical parameters of the model. Using Bayesian inference, we represent the expensive atomistic component by a surrogate model that relates the long-term output of the atomistic simulation to its uncertain inputs. We then present algorithms to solve for the variables exchanged across the atomistic-continuum interface in terms of polynomial chaos expansions (PCEs). We alsomore » consider a simple Couette flow where velocities are exchanged between the atomistic and continuum components, while accounting for uncertainty in the atomistic model parameters and the continuum boundary conditions. Results show convergence of the coupling algorithm at a reasonable number of iterations. As a result, the uncertainty in the obtained variables significantly depends on the amount of data sampled from the MD simulations and on the width of the time averaging window used in the MD simulations.« less

Uncertainty estimation in the determination of metals in superficial water by ICP-OES

NASA Astrophysics Data System (ADS)

Faustino, Mainara G.; Marques, Joyce R.; Monteiro, Lucilena R.; Stellato, Thamiris B.; Soares, Sabrina M. V.; Silva, Tatiane B. S. C.; da Silva, Douglas B.; Pires, Maria Aparecida F.; Cotrim, Marycel E. B.

2016-07-01

From validation studies, it was possible to estimate a measurement uncertainty of several elements such as Al, Ba, Ca, Cu, Cr, Cd, Fe, Mg, Mn, Ni and K in water samples from Guarapiranga Dam. These elements were analyzed by optical emission spectrometry with inductively coupled plasma (ICP-OES). The value of relative estimated uncertainties were between 3% and 15%. The greatest uncertainty contributions were analytical curve, and the recovery method, which were related with elements concentrations and the equipment response. Water samples analyzed were compared with CONAMA Resolution #357/2005.

Quantification of model uncertainty in aerosol optical thickness retrieval from Ozone Monitoring Instrument (OMI) measurements

NASA Astrophysics Data System (ADS)

Määttä, A.; Laine, M.; Tamminen, J.; Veefkind, J. P.

2013-09-01

We study uncertainty quantification in remote sensing of aerosols in the atmosphere with top of the atmosphere reflectance measurements from the nadir-viewing Ozone Monitoring Instrument (OMI). Focus is on the uncertainty in aerosol model selection of pre-calculated aerosol models and on the statistical modelling of the model inadequacies. The aim is to apply statistical methodologies that improve the uncertainty estimates of the aerosol optical thickness (AOT) retrieval by propagating model selection and model error related uncertainties more realistically. We utilise Bayesian model selection and model averaging methods for the model selection problem and use Gaussian processes to model the smooth systematic discrepancies from the modelled to observed reflectance. The systematic model error is learned from an ensemble of operational retrievals. The operational OMI multi-wavelength aerosol retrieval algorithm OMAERO is used for cloud free, over land pixels of the OMI instrument with the additional Bayesian model selection and model discrepancy techniques. The method is demonstrated with four examples with different aerosol properties: weakly absorbing aerosols, forest fires over Greece and Russia, and Sahara dessert dust. The presented statistical methodology is general; it is not restricted to this particular satellite retrieval application.

Fifth International Conference on Squeezed States and Uncertainty Relations

NASA Technical Reports Server (NTRS)

Han, D. (Editor); Janszky, J. (Editor); Kim, Y. S. (Editor); Man'ko, V. I. (Editor)

1998-01-01

The Fifth International Conference on Squeezed States and Uncertainty Relations was held at Balatonfured, Hungary, on 27-31 May 1997. This series was initiated in 1991 at the College Park Campus of the University of Maryland as the Workshop on Squeezed States and Uncertainty Relations. The scientific purpose of this series was to discuss squeezed states of light, but in recent years the scope is becoming broad enough to include studies of uncertainty relations and squeeze transformations in all branches of physics including quantum optics and foundations of quantum mechanics. Quantum optics will continue playing the pivotal role in the future, but the future meetings will include all branches of physics where squeeze transformations are basic. As the meeting attracted more participants and started covering more diversified subjects, the fourth meeting was called an international conference. The Fourth International Conference on Squeezed States and Uncertainty Relations was held in 1995 was hosted by Shanxi University in Taiyuan, China. The fifth meeting of this series, which was held at Balatonfured, Hungary, was also supported by the IUPAP. In 1999, the Sixth International Conference will be hosted by the University of Naples in 1999. The meeting will take place in Ravello near Naples.

Uncertainty Quantification in Remaining Useful Life of Aerospace Components using State Space Models and Inverse FORM

NASA Technical Reports Server (NTRS)

Sankararaman, Shankar; Goebel, Kai

2013-01-01

This paper investigates the use of the inverse first-order reliability method (inverse- FORM) to quantify the uncertainty in the remaining useful life (RUL) of aerospace components. The prediction of remaining useful life is an integral part of system health prognosis, and directly helps in online health monitoring and decision-making. However, the prediction of remaining useful life is affected by several sources of uncertainty, and therefore it is necessary to quantify the uncertainty in the remaining useful life prediction. While system parameter uncertainty and physical variability can be easily included in inverse-FORM, this paper extends the methodology to include: (1) future loading uncertainty, (2) process noise; and (3) uncertainty in the state estimate. The inverse-FORM method has been used in this paper to (1) quickly obtain probability bounds on the remaining useful life prediction; and (2) calculate the entire probability distribution of remaining useful life prediction, and the results are verified against Monte Carlo sampling. The proposed methodology is illustrated using a numerical example.

Deriving the concentration of airborne ash with a CAS-DPOL instrument: assessing uncertainties introduced by the instrument design

NASA Astrophysics Data System (ADS)

Spanu, Antonio; Weinzierl, Bernadett; Freudenthaler, Volker; Sauer, Daniel; Gasteiger, Josef

2016-04-01

Explosive volcanic eruptions inject large amounts of gas and particles into the atmosphere resulting in strong impacts on anthropic systems and climate. Fine ash particles in suspension, even if at low concentrations, are a serious aviation safety hazard. A key point to predict the dispersion and deposition of volcanic ash is the knowledge of emitted mass and its particle size distribution. Usually the deposit is used to characterize the source but a large uncertainty is present for fine and very fine ash particles which are usually not well preserved. Conversely, satellite observations provide only column-integrated information and are strongly sensitive to cloud conditions above the ash plumes. Consequently, in situ measurements are fundamental to extend our knowledge on ash clouds, their properties, and interactions over the vertical extent of the atmosphere. Different in-situ instruments are available covering different particle size ranges using a variety of measurement techniques. Depending on the measurement technique, artefacts due to instrument setup and ambient conditions can strongly modify the measured number concentration and size distribution of the airborne particles. It is fundamental to correct for those effects to quantify the uncertainty associated with the measurement. Here we evaluate the potential of our optical light-scattering spectrometer CAS-DPOL to detect airborne mineral dust and volcanic ash (in the size range between 0.7μm and 50μm) and to provide a reliable estimation of the mass concentration, investigating the associate uncertainty. The CAS-DPOL instrument sizes particles by detecting the light scattered off the particle into a defined angle. The associated uncertainty depends on the optical instrument design and on unknown particles characteristics such as shape and material. Indirect measurements of mass concentrations are statistically reconstructed using the air flow velocity. Therefore, the detected concentration is strongly sensitive to the sample flow and on the mechanical instrument design. Using a fluid dynamics model coupled with an optical model we analyze the effects of instrument design on the measurement, identify measurement uncertainties and recommend strategies to reduce the uncertainties. The two main results are that the optical design of the CAS-DPOL aerosol spectrometer can lead to an under-counting bias of up to 40% for larger particles and an over-counting bias of 20%-30% for smaller particles. Secondly, depending on how the instrument is mounted on the plane, the sampling can be subject to a significantly larger size selection bias than typically recognized, especially if the mounting leads to irregular sampling conditions. To correct both problems a new correction algorithm is described generalizing the results also to other optical particle counters. Finally, a comparison study is presented showing the effects on mass estimation and radiative forcing for uncorrected and corrected data also stating the resulting uncertainty.

Is the aerosol emission detectable in the thermal infrared?

NASA Astrophysics Data System (ADS)

Hollweg, H.-D.; Bakan, S.; Taylor, J. P.

2006-08-01

The impact of aerosols on the thermal infrared radiation can be assessed by combining observations and radiative transfer calculations. Both have uncertainties, which are discussed in this paper. Observational uncertainties are obtained for two FTIR instruments operated side by side on the ground during the LACE 1998 field campaign. Radiative transfer uncertainties are assessed using a line-by-line model taking into account the uncertainties of the HITRAN 2004 spectroscopic database, uncertainties in the determination of the atmospheric profiles of water vapor and ozone, and differences in the treatment of the water vapor continuum absorption by the CKD 2.4.1 and MT_CKD 1.0 algorithms. The software package OPAC was used to describe the optical properties of aerosols for climate modeling. The corresponding radiative signature is a guideline to the assessment of the uncertainty ranges of observations and models. We found that the detection of aerosols depends strongly on the measurement accuracy of atmospheric profiles of water vapor and ozone and is easier for drier conditions. Within the atmospheric window, only the forcing of downward radiation at the surface by desert aerosol emerges clearly from the uncertainties of modeling and FTIR measurement. Urban and polluted continental aerosols are only partially detectable depending on the wave number and on the atmospheric water vapor amount. Simulations for the space-borne interferometer IASI show that only upward radiation above transported mineral dust aloft emerges out of the uncertainties. The detection of aerosols with weak radiative impact by FTIR instruments like ARIES and OASIS is made difficult by noise as demonstrated by the signal to noise ratio for clean continental aerosols. Altogether, the uncertainties found suggest that it is difficult to detect the optical depths of nonmineral and unpolluted aerosols.

Visualizing Java uncertainty

NASA Astrophysics Data System (ADS)

Knight, Claire; Munro, Malcolm

2001-07-01

Distributed component based systems seem to be the immediate future for software development. The use of such techniques, object oriented languages, and the combination with ever more powerful higher-level frameworks has led to the rapid creation and deployment of such systems to cater for the demand of internet and service driven business systems. This diversity of solution through both components utilised and the physical/virtual locations of those components can provide powerful resolutions to the new demand. The problem lies in the comprehension and maintenance of such systems because they then have inherent uncertainty. The components combined at any given time for a solution may differ, the messages generated, sent, and/or received may differ, and the physical/virtual locations cannot be guaranteed. Trying to account for this uncertainty and to build in into analysis and comprehension tools is important for both development and maintenance activities.

Reconstructing the stellar mass distributions of galaxies using S{sup 4}G IRAC 3.6 and 4.5 μm images. II. The conversion from light to mass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meidt, Sharon E.; Schinnerer, Eva; Van de Ven, Glenn

2014-06-20

We present a new approach for estimating the 3.6 μm stellar mass-to-light (M/L) ratio Y{sub 3.6} in terms of the [3.6]-[4.5] colors of old stellar populations. Our approach avoids several of the largest sources of uncertainty in existing techniques using population synthesis models. By focusing on mid-IR wavelengths, we gain a virtually dust extinction-free tracer of the old stars, avoiding the need to adopt a dust model to correctly interpret optical or optical/near-IR colors normally leveraged to assign the mass-to-light ratio Y. By calibrating a new relation between near-IR and mid-IR colors of giant stars observed in GLIMPSE we alsomore » avoid the discrepancies in model predictions for the [3.6]-[4.5] colors of old stellar populations due to uncertainties in the molecular line opacities assumed in template spectra. We find that the [3.6]-[4.5] color, which is driven primarily by metallicity, provides a tight constraint on Y{sub 3.6}, which varies intrinsically less than at optical wavelengths. The uncertainty on Y{sub 3.6} of ∼0.07 dex due to unconstrained age variations marks a significant improvement on existing techniques for estimating the stellar M/L with shorter wavelength data. A single Y{sub 3.6} = 0.6 (assuming a Chabrier initial mass function (IMF)), independent of [3.6]-[4.5] color, is also feasible because it can be applied simultaneously to old, metal-rich and young, metal-poor populations, and still with comparable (or better) accuracy (∼0.1 dex) than alternatives. We expect our Y{sub 3.6} to be optimal for mapping the stellar mass distributions in S{sup 4}G galaxies, for which we have developed an independent component analysis technique to first isolate the old stellar light at 3.6 μm from nonstellar emission (e.g., hot dust and the 3.3 polycyclic aromatic hydrocarbon feature). Our estimate can also be used to determine the fractional contribution of nonstellar emission to global (rest-frame) 3.6 μm fluxes, e.g., in WISE imaging, and establishes a reliable basis for exploring variations in the stellar IMF.« less

Characterizing Epistemic Uncertainty for Launch Vehicle Designs

NASA Technical Reports Server (NTRS)

Novack, Steven D.; Rogers, Jim; Al Hassan, Mohammad; Hark, Frank

2016-01-01

NASA Probabilistic Risk Assessment (PRA) has the task of estimating the aleatory (randomness) and epistemic (lack of knowledge) uncertainty of launch vehicle loss of mission and crew risk, and communicating the results. Launch vehicles are complex engineered systems designed with sophisticated subsystems that are built to work together to accomplish mission success. Some of these systems or subsystems are in the form of heritage equipment, while some have never been previously launched. For these cases, characterizing the epistemic uncertainty is of foremost importance, and it is anticipated that the epistemic uncertainty of a modified launch vehicle design versus a design of well understood heritage equipment would be greater. For reasons that will be discussed, standard uncertainty propagation methods using Monte Carlo simulation produce counter intuitive results, and significantly underestimate epistemic uncertainty for launch vehicle models. Furthermore, standard PRA methods, such as Uncertainty-Importance analyses used to identify components that are significant contributors to uncertainty, are rendered obsolete, since sensitivity to uncertainty changes are not reflected in propagation of uncertainty using Monte Carlo methods. This paper provides a basis of the uncertainty underestimation for complex systems and especially, due to nuances of launch vehicle logic, for launch vehicles. It then suggests several alternative methods for estimating uncertainty and provides examples of estimation results. Lastly, the paper describes how to implement an Uncertainty-Importance analysis using one alternative approach, describes the results, and suggests ways to reduce epistemic uncertainty by focusing on additional data or testing of selected components.

Characterizing Epistemic Uncertainty for Launch Vehicle Designs

NASA Technical Reports Server (NTRS)

Novack, Steven D.; Rogers, Jim; Hark, Frank; Al Hassan, Mohammad

2016-01-01

NASA Probabilistic Risk Assessment (PRA) has the task of estimating the aleatory (randomness) and epistemic (lack of knowledge) uncertainty of launch vehicle loss of mission and crew risk and communicating the results. Launch vehicles are complex engineered systems designed with sophisticated subsystems that are built to work together to accomplish mission success. Some of these systems or subsystems are in the form of heritage equipment, while some have never been previously launched. For these cases, characterizing the epistemic uncertainty is of foremost importance, and it is anticipated that the epistemic uncertainty of a modified launch vehicle design versus a design of well understood heritage equipment would be greater. For reasons that will be discussed, standard uncertainty propagation methods using Monte Carlo simulation produce counter intuitive results and significantly underestimate epistemic uncertainty for launch vehicle models. Furthermore, standard PRA methods such as Uncertainty-Importance analyses used to identify components that are significant contributors to uncertainty are rendered obsolete since sensitivity to uncertainty changes are not reflected in propagation of uncertainty using Monte Carlo methods.This paper provides a basis of the uncertainty underestimation for complex systems and especially, due to nuances of launch vehicle logic, for launch vehicles. It then suggests several alternative methods for estimating uncertainty and provides examples of estimation results. Lastly, the paper shows how to implement an Uncertainty-Importance analysis using one alternative approach, describes the results, and suggests ways to reduce epistemic uncertainty by focusing on additional data or testing of selected components.

Modelling the optical properties of aerosols in a chemical transport model

NASA Astrophysics Data System (ADS)

Andersson, E.; Kahnert, M.

2015-12-01

According to the IPCC fifth assessment report (2013), clouds and aerosols still contribute to the largest uncertainty when estimating and interpreting changes to the Earth's energy budget. Therefore, understanding the interaction between radiation and aerosols is both crucial for remote sensing observations and modelling the climate forcing arising from aerosols. Carbon particles are the largest contributor to the aerosol absorption of solar radiation, thereby enhancing the warming of the planet. Modelling the radiative properties of carbon particles is a hard task and involves many uncertainties arising from the difficulties of accounting for the morphologies and heterogeneous chemical composition of the particles. This study aims to compare two ways of modelling the optical properties of aerosols simulated by a chemical transport model. The first method models particle optical properties as homogeneous spheres and are externally mixed. This is a simple model that is particularly easy to use in data assimilation methods, since the optics model is linear. The second method involves a core-shell internal mixture of soot, where sulphate, nitrate, ammonia, organic carbon, sea salt, and water are contained in the shell. However, by contrast to previously used core-shell models, only part of the carbon is concentrated in the core, while the remaining part is homogeneously mixed with the shell. The chemical transport model (CTM) simulations are done regionally over Europe with the Multiple-scale Atmospheric Transport and CHemistry (MATCH) model, developed by the Swedish Meteorological and Hydrological Institute (SMHI). The MATCH model was run with both an aerosol dynamics module, called SALSA, and with a regular "bulk" approach, i.e., a mass transport model without aerosol dynamics. Two events from 2007 are used in the analysis, one with high (22/12-2007) and one with low (22/6-2007) levels of elemental carbon (EC) over Europe. The results of the study help to assess the significance of aerosol morphology for modelling radiative forcing and aerosol optical properties relevant to interpreting remote sensing observations. The uncertainties introduced by the optics model are gauged by comparing them to model uncertainties related to the inclusion or omission of aerosol dynamic processes.

Global observations of aerosol-cloud-precipitation-climate interactions

NASA Astrophysics Data System (ADS)

Rosenfeld, Daniel; Andreae, Meinrat O.; Asmi, Ari; Chin, Mian; de Leeuw, Gerrit; Donovan, David P.; Kahn, Ralph; Kinne, Stefan; Kivekäs, Niku; Kulmala, Markku; Lau, William; Schmidt, K. Sebastian; Suni, Tanja; Wagner, Thomas; Wild, Martin; Quaas, Johannes

2014-12-01

Cloud drop condensation nuclei (CCN) and ice nuclei (IN) particles determine to a large extent cloud microstructure and, consequently, cloud albedo and the dynamic response of clouds to aerosol-induced changes to precipitation. This can modify the reflected solar radiation and the thermal radiation emitted to space. Measurements of tropospheric CCN and IN over large areas have not been possible and can be only roughly approximated from satellite-sensor-based estimates of optical properties of aerosols. Our lack of ability to measure both CCN and cloud updrafts precludes disentangling the effects of meteorology from those of aerosols and represents the largest component in our uncertainty in anthropogenic climate forcing. Ways to improve the retrieval accuracy include multiangle and multipolarimetric passive measurements of the optical signal and multispectral lidar polarimetric measurements. Indirect methods include proxies of trace gases, as retrieved by hyperspectral sensors. Perhaps the most promising emerging direction is retrieving the CCN properties by simultaneously retrieving convective cloud drop number concentrations and updraft speeds, which amounts to using clouds as natural CCN chambers. These satellite observations have to be constrained by in situ observations of aerosol-cloud-precipitation-climate (ACPC) interactions, which in turn constrain a hierarchy of model simulations of ACPC. Since the essence of a general circulation model is an accurate quantification of the energy and mass fluxes in all forms between the surface, atmosphere and outer space, a route to progress is proposed here in the form of a series of box flux closure experiments in the various climate regimes. A roadmap is provided for quantifying the ACPC interactions and thereby reducing the uncertainty in anthropogenic climate forcing.

Assessment of Satellite Ocean Colour Radiometry and Derived Geophysical Products. Chapter 6.1

NASA Technical Reports Server (NTRS)

Melin, Frederic; Franz, Bryan A.

2014-01-01

Standardization of methods to assess and assign quality metrics to satellite ocean color radiometry and derived geophysical products has become paramount with the inclusion of the marine reflectance and chlorophyll-a concentration (Chla) as essential climate variables (ECV; [1]) and the recognition that optical remote sensing of the oceans can only contribute to climate research if and when a continuous succession of satellite missions can be shown to collectively provide a consistent, long-term record with known uncertainties. In 20 years, the community has made significant advancements toward that objective, but providing a complete uncertainty budget for all products and for all conditions remains a daunting task. In the retrieval of marine water-leaving radiance from observed top-of-atmosphere radiance, the sources of uncertainties include those associated with propagation of sensor noise and radiometric calibration and characterization errors, as well as a multitude of uncertainties associated with the modeling and removal of effects from the atmosphere and sea surface. This chapter describes some common approaches used to assess quality and consistency of ocean color satellite products and reviews the current status of uncertainty quantification in the field. Its focus is on the primary ocean color product, the spectrum of marine reflectance Rrs, but uncertainties in some derived products such as the Chla or inherent optical properties (IOPs) will also be considered.

High-precision diode-laser-based temperature measurement for air refractive index compensation.

PubMed

Hieta, Tuomas; Merimaa, Mikko; Vainio, Markku; Seppä, Jeremias; Lassila, Antti

2011-11-01

We present a laser-based system to measure the refractive index of air over a long path length. In optical distance measurements, it is essential to know the refractive index of air with high accuracy. Commonly, the refractive index of air is calculated from the properties of the ambient air using either Ciddor or Edlén equations, where the dominant uncertainty component is in most cases the air temperature. The method developed in this work utilizes direct absorption spectroscopy of oxygen to measure the average temperature of air and of water vapor to measure relative humidity. The method allows measurement of temperature and humidity over the same beam path as in optical distance measurement, providing spatially well-matching data. Indoor and outdoor measurements demonstrate the effectiveness of the method. In particular, we demonstrate an effective compensation of the refractive index of air in an interferometric length measurement at a time-variant and spatially nonhomogeneous temperature over a long time period. Further, we were able to demonstrate 7 mK RMS noise over a 67 m path length using a 120 s sample time. To our knowledge, this is the best temperature precision reported for a spectroscopic temperature measurement. © 2011 Optical Society of America

Optics Program Simplifies Analysis and Design

NASA Technical Reports Server (NTRS)

2007-01-01

Engineers at Goddard Space Flight Center partnered with software experts at Mide Technology Corporation, of Medford, Massachusetts, through a Small Business Innovation Research (SBIR) contract to design the Disturbance-Optics-Controls-Structures (DOCS) Toolbox, a software suite for performing integrated modeling for multidisciplinary analysis and design. The DOCS Toolbox integrates various discipline models into a coupled process math model that can then predict system performance as a function of subsystem design parameters. The system can be optimized for performance; design parameters can be traded; parameter uncertainties can be propagated through the math model to develop error bounds on system predictions; and the model can be updated, based on component, subsystem, or system level data. The Toolbox also allows the definition of process parameters as explicit functions of the coupled model and includes a number of functions that analyze the coupled system model and provide for redesign. The product is being sold commercially by Nightsky Systems Inc., of Raleigh, North Carolina, a spinoff company that was formed by Mide specifically to market the DOCS Toolbox. Commercial applications include use by any contractors developing large space-based optical systems, including Lockheed Martin Corporation, The Boeing Company, and Northrup Grumman Corporation, as well as companies providing technical audit services, like General Dynamics Corporation

FIBER AND INTEGRATED OPTICS, LASER APPLICATIONS, AND OTHER PROBLEMS IN QUANTUM ELECTRONICS: Optical components for the analysis and formation of the transverse mode composition

NASA Astrophysics Data System (ADS)

Golub, M. A.; Sisakyan, I. N.; Soĭfer, V. A.; Uvarov, G. V.

1989-04-01

Theoretical and experimental investigations are reported of new mode optical components (elements) which are analogs of sinusoidal phase diffraction gratings with a variable modulation depth. Expressions are derived for nonlinear predistortion and depth of modulation, which are essential for effective operation of amplitude and phase mode optical components in devices used for analysis and formation of the transverse mode composition of coherent radiation. An estimate is obtained of the energy efficiency of phase and amplitude mode optical components, and a comparison is made with the results of an experimental investigation of a set of phase optical components matched to Gauss-Laguerre modes. It is shown that the improvement in the energy efficiency of phase mode components, compared with amplitude components, is the same as the improvement achieved using a phase diifraction grating, compared with amplitude grating with the same depth of modulation.

A Precise Physical Orbit For The M-Dwarf Binary Gliese 268

NASA Technical Reports Server (NTRS)

Barry, R. K.; Demory, B. -O.; Segransan, D.; Forveille, T.; Danchi, W. C.; Di Folco, E.; Queloz, D.; Spooner, H. R.; Torres, G.; Traub, W. A.;

Hybrid optical (freeform) components--functionalization of nonplanar optical surfaces by direct picosecond laser ablation.

PubMed

Kleindienst, Roman; Kampmann, Ronald; Stoebenau, Sebastian; Sinzinger, Stefan

2011-07-01

The performance of optical systems is typically improved by increasing the number of conventionally fabricated optical components (spheres, aspheres, and gratings). This approach is automatically connected to a system enlargement, as well as potentially higher assembly and maintenance costs. Hybrid optical freeform components can help to overcome this trade-off. They merge several optical functions within fewer but more complex optical surfaces, e.g., elements comprising shallow refractive/reflective and high-frequency diffractive structures. However, providing the flexibility and precision essential for their realization is one of the major challenges in the field of optical component fabrication. In this article we present tailored integrated machining techniques suitable for rapid prototyping as well as the fabrication of molding tools for low-cost mass replication of hybrid optical freeform components. To produce the different feature sizes with optical surface quality, we successively combine mechanical machining modes (ultraprecision micromilling and fly cutting) with precisely aligned direct picosecond laser ablation in an integrated fabrication approach. The fabrication accuracy and surface quality achieved by our integrated fabrication approach are demonstrated with profilometric measurements and experimental investigations of the optical performance.

Uncertainty of Videogrammetric Techniques used for Aerodynamic Testing

NASA Technical Reports Server (NTRS)

Burner, A. W.; Liu, Tianshu; DeLoach, Richard

2002-01-01

The uncertainty of videogrammetric techniques used for the measurement of static aeroelastic wind tunnel model deformation and wind tunnel model pitch angle is discussed. Sensitivity analyses and geometrical considerations of uncertainty are augmented by analyses of experimental data in which videogrammetric angle measurements were taken simultaneously with precision servo accelerometers corrected for dynamics. An analysis of variance (ANOVA) to examine error dependence on angle of attack, sensor used (inertial or optical). and on tunnel state variables such as Mach number is presented. Experimental comparisons with a high-accuracy indexing table are presented. Small roll angles are found to introduce a zero-shift in the measured angles. It is shown experimentally that. provided the proper constraints necessary for a solution are met, a single- camera solution can he comparable to a 2-camera intersection result. The relative immunity of optical techniques to dynamics is illustrated.

Surface Figure Measurement of Silicon Carbide Mirrors at Cryogenic Temperatures

NASA Technical Reports Server (NTRS)

Blake, Peter; Mink, Ronald G.; Chambers, John; Robinson, F. David; Content, David; Davila, Pamela

2005-01-01

The surface figure of a developmental silicon carbide mirror, cooled to 87 K and then 20 K within a cryostat, was measured with unusually high precision at the Goddard Space Flight Center (GSFC). The concave spherical mirror, with a radius of 600 mm and a clear aperture of 150 mm, was fabricated of sintered silicon carbide. The mirror was mounted to an interface plate representative of an optical bench, made of the material Cesic@, a composite of silicon, carbon, and silicon carbide. The change in optical surface figure as the mirror and interface plate cooled from room temperature to 20 K was 3.7 nm rms, with a standard uncertainty of 0.23 nm in the rms statistic. Both the cryo-change figure and the uncertainty are among the lowest such figures yet published. This report describes the facilities, experimental methods, and uncertainty analysis of the measurements.

an aerosol climatology optical properties and its associated direct radiative forcing

NASA Astrophysics Data System (ADS)

Kinne, Stefan

2010-05-01

Aerosol particles are quite complex in nature. Aerosol impacts on the distribution of radiative energy and on cloud microphysics have been debated climate impact issues. Here, a new aerosol-climatology is presented, combining the consistency and completeness of global modelling with quality data by ground-monitoring. It provides global monthly maps for spectral aerosol optical properties and for concentrations of CCN and IN. Based on the optical properties the aerosol direct forcing is determined. And with environmental data for clouds and estimates on the anthropogenic fraction from emission experiments with global modelling even the climate relevant aerosol direct forcing at the top of the atmosphere (ToA) is determined. This value is rather small near -0.2W/m2 with limited uncertainty estimated at (+/-0.3) due to uncertainties in aerosol absorption and underlying surface conditions or clouds.

Specimen illumination apparatus with optical cavity for dark field illumination

DOEpatents

Pinkel, Daniel; Sudar, Damir; Albertson, Donna

1999-01-01

An illumination apparatus with a specimen slide holder, an illumination source, an optical cavity producing multiple reflection of illumination light to a specimen comprising a first and a second reflective surface arranged to achieve multiple reflections of light to a specimen is provided. The apparatus can further include additional reflective surfaces to achieve the optical cavity, a slide for mounting the specimen, a coverslip which is a reflective component of the optical cavity, one or more prisms for directing light within the optical cavity, antifading solutions for improving the viewing properties of the specimen, an array of materials for analysis, fluorescent components, curved reflective surfaces as components of the optical cavity, specimen detection apparatus, optical detection equipment, computers for analysis of optical images, a plane polarizer, fiberoptics, light transmission apertures, microscopic components, lenses for viewing the specimen, and upper and lower mirrors above and below the specimen slide as components of the optical cavity. Methods of using the apparatus are also provided.

Hydrogeologic setting and preliminary estimates of hydrologic components for Bull Run Lake and the Bull Run Lake drainage basin, Multnomah and Clackamas counties, Oregon

USGS Publications Warehouse

Snyder, Daniel T.; Brownell, Dorie L.

1996-01-01

Suggestions for further study include (1) evaluation of the surface-runoff component of inflow to the lake; (2) use of a cross-sectional ground-water flow model to estimate ground-water inflow, outflow, and storage; (3) additional data collection to reduce the uncertainties of the hydrologic components that have large relative uncertainties; and (4) determination of long-term trends for a wide range of climatic and hydrologic conditions.

Optical CDMA components requirements

NASA Astrophysics Data System (ADS)

Chan, James K.

1998-08-01

Optical CDMA is a complementary multiple access technology to WDMA. Optical CDMA potentially provides a large number of virtual optical channels for IXC, LEC and CLEC or supports a large number of high-speed users in LAN. In a network, it provides asynchronous, multi-rate, multi-user communication with network scalability, re-configurability (bandwidth on demand), and network security (provided by inherent CDMA coding). However, optical CDMA technology is less mature in comparison to WDMA. The components requirements are also different from WDMA. We have demonstrated a video transport/switching system over a distance of 40 Km using discrete optical components in our laboratory. We are currently pursuing PIC implementation. In this paper, we will describe the optical CDMA concept/features, the demonstration system, and the requirements of some critical optical components such as broadband optical source, broadband optical amplifier, spectral spreading/de- spreading, and fixed/programmable mask.

Aerosol optical depth (AOD) and Angstrom exponent of aerosols observed by the Chinese Sun Hazemeter Network from August 2004 to September 2005

Treesearch

Jinyuan Xin; Yuesi Wang; Zhanqing Li; Pucai Wang; Wei Min Hao; Bryce L. Nordgren; Shigong Wang; Guangren Lui; Lili Wang; Tianxue Wen; Yang Sun; Bo Hu

2007-01-01

To reduce uncertainties in the quantitative assessment of aerosol effects on regional climate and environmental changes, extensive measurements of aerosol optical properties were made with handheld Sun photometers in the Chinese Sun Hazemeter Network (CSHNET) starting in August 2004. Regional characteristics of the aerosol optical depth (AOD) at 500 nm and Angstrom...

INSPECTION SHOP: PLAN TO PROVIDE UNCERTAINTY ANALYSIS WITH MEASUREMENTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nederbragt, W W

The LLNL inspection shop is chartered to make dimensional measurements of components for critical programmatic experiments. These measurements ensure that components are within tolerance and provide geometric details that can be used to further refine simulations. For these measurements to be useful, they must be significantly more accurate than the tolerances that are being checked. For example, if a part has a specified dimension of 100 millimeters and a tolerance of 1 millimeter, then the precision and/or accuracy of the measurement should be less than 1 millimeter. Using the ''10-to-1 gaugemaker's rule of thumb'', the desired precision of the measurementmore » should be less than 100 micrometers. Currently, the process for associating measurement uncertainty with data is not standardized, nor is the uncertainty based on a thorough uncertainty analysis. The goal of this project is to begin providing measurement uncertainty statements with critical measurements performed in the inspection shop. To accomplish this task, comprehensive knowledge about the underlying sources of uncertainty for measurement instruments need to be understood and quantified. Moreover, measurements of elemental uncertainties for each physical source need to be combined in a meaningful way to obtain an overall measurement uncertainty.« less

Quantification of uncertainty in flood risk assessment for flood protection planning: a Bayesian approach

NASA Astrophysics Data System (ADS)

Dittes, Beatrice; Špačková, Olga; Ebrahimian, Negin; Kaiser, Maria; Rieger, Wolfgang; Disse, Markus; Straub, Daniel

2017-04-01

Flood risk estimates are subject to significant uncertainties, e.g. due to limited records of historic flood events, uncertainty in flood modeling, uncertain impact of climate change or uncertainty in the exposure and loss estimates. In traditional design of flood protection systems, these uncertainties are typically just accounted for implicitly, based on engineering judgment. In the AdaptRisk project, we develop a fully quantitative framework for planning of flood protection systems under current and future uncertainties using quantitative pre-posterior Bayesian decision analysis. In this contribution, we focus on the quantification of the uncertainties and study their relative influence on the flood risk estimate and on the planning of flood protection systems. The following uncertainty components are included using a Bayesian approach: 1) inherent and statistical (i.e. limited record length) uncertainty; 2) climate uncertainty that can be learned from an ensemble of GCM-RCM models; 3) estimates of climate uncertainty components not covered in 2), such as bias correction, incomplete ensemble, local specifics not captured by the GCM-RCM models; 4) uncertainty in the inundation modelling; 5) uncertainty in damage estimation. We also investigate how these uncertainties are possibly reduced in the future when new evidence - such as new climate models, observed extreme events, and socio-economic data - becomes available. Finally, we look into how this new evidence influences the risk assessment and effectivity of flood protection systems. We demonstrate our methodology for a pre-alpine catchment in southern Germany: the Mangfall catchment in Bavaria that includes the city of Rosenheim, which suffered significant losses during the 2013 flood event.

High-efficiency high-reliability optical components for a large, high-average-power visible laser system

NASA Astrophysics Data System (ADS)

Taylor, John R.; Stolz, Christopher J.

1993-08-01

Laser system performance and reliability depends on the related performance and reliability of the optical components which define the cavity and transport subsystems. High-average-power and long transport lengths impose specific requirements on component performance. The complexity of the manufacturing process for optical components requires a high degree of process control and verification. Qualification has proven effective in ensuring confidence in the procurement process for these optical components. Issues related to component reliability have been studied and provide useful information to better understand the long term performance and reliability of the laser system.

High-efficiency high-reliability optical components for a large, high-average-power visible laser system

NASA Astrophysics Data System (ADS)

Taylor, J. R.; Stolz, C. J.

1992-12-01

Laser system performance and reliability depends on the related performance and reliability of the optical components which define the cavity and transport subsystems. High-average-power and long transport lengths impose specific requirements on component performance. The complexity of the manufacturing process for optical components requires a high degree of process control and verification. Qualification has proven effective in ensuring confidence in the procurement process for these optical components. Issues related to component reliability have been studied and provide useful information to better understand the long term performance and reliability of the laser system.

Conceptual design of an on-board optical processor with components

NASA Technical Reports Server (NTRS)

Walsh, J. R.; Shackelford, R. G.

1977-01-01

The specification of components for a spacecraft on-board optical processor was investigated. A space oriented application of optical data processing and the investigation of certain aspects of optical correlators were examined. The investigation confirmed that real-time optical processing has made significant advances over the past few years, but that there are still critical components which will require further development for use in an on-board optical processor. The devices evaluated were the coherent light valve, the readout optical modulator, the liquid crystal modulator, and the image forming light modulator.

Optical path switching based differential absorption radiometry for substance detection

NASA Technical Reports Server (NTRS)

Sachse, Glen W. (Inventor)

2005-01-01

An optical path switch divides sample path radiation into a time series of alternating first polarized components and second polarized components. The first polarized components are transmitted along a first optical path and the second polarized components along a second optical path. A first gasless optical filter train filters the first polarized components to isolate at least a first wavelength band thereby generating first filtered radiation. A second gasless optical filter train filters the second polarized components to isolate at least a second wavelength band thereby generating second filtered radiation. A beam combiner combines the first and second filtered radiation to form a combined beam of radiation. A detector is disposed to monitor magnitude of at least a portion of the combined beam alternately at the first wavelength band and the second wavelength band as an indication of the concentration of the substance in the sample path.

Optical path switching based differential absorption radiometry for substance detection

NASA Technical Reports Server (NTRS)

Sachse, Glen W. (Inventor)

2003-01-01

An optical path switch divides sample path radiation into a time series of alternating first polarized components and second polarized components. The first polarized components are transmitted along a first optical path and the second polarized components along a second optical path. A first gasless optical filter train filters the first polarized components to isolate at least a first wavelength band thereby generating first filtered radiation. A second gasless optical filter train filters the second polarized components to isolate at least a second wavelength band thereby generating second filtered radiation. A beam combiner combines the first and second filtered radiation to form a combined beam of radiation. A detector is disposed to monitor magnitude of at least a portion of the combined beam alternately at the first wavelength band and the second wavelength band as an indication of the concentration of the substance in the sample path.

Sensitivity of Multiangle Imaging to the Optical and Microphysical Properties of Biomass Burning Aerosols

NASA Technical Reports Server (NTRS)

Chen, Wei-Ting; Kahn, Ralph A.; Nelson, David; Yau, Kevin; Seinfeld, John H.

2008-01-01

The treatment of biomass burning (BB) carbonaceous particles in the Multiangle Imaging SpectroRadiometer (MISR) Standard Aerosol Retrieval Algorithm is assessed, and algorithm refinements are suggested, based on a theoretical sensitivity analysis and comparisons with near-coincident AERONET measurements at representative BB sites. Over the natural ranges of BB aerosol microphysical and optical properties observed in past field campaigns, patterns of retrieved Aerosol Optical Depth (AOD), particle size, and single scattering albedo (SSA) are evaluated. On the basis of the theoretical analysis, assuming total column AOD of 0.2, over a dark, uniform surface, MISR can distinguish two to three groups in each of size and SSA, except when the assumed atmospheric particles are significantly absorbing (mid-visible SSA approx.0.84), or of medium sizes (mean radius approx.0.13 pin); sensitivity to absorbing, medium-large size particles increases considerably when the assumed column AOD is raised to 0.5. MISR Research Aerosol Retrievals confirm the theoretical results, based on coincident AERONET inversions under BB-dominated conditions. When BB is externally mixed with dust in the atmosphere, dust optical model and surface reflection uncertainties, along with spatial variability, contribute to differences between the Research Retrievals and AERONET. These results suggest specific refinements to the MISR Standard Aerosol Algorithm complement of component particles and mixtures. They also highlight the importance for satellite aerosol retrievals of surface reflectance characterization, with accuracies that can be difficult to achieve with coupled surface-aerosol algorithms in some higher AOD situations.

A comparison of uncertainties in the aerosol direct radiative effect in the SE U.S. calculated using satellite-based and ground-based aerosol properties

NASA Astrophysics Data System (ADS)

Sherman, J. P.

2017-12-01

Satellite-retrieved aerosol optical depth is typically used for measurement-based estimates of the aerosol direct radiative effect (DRE) on solar radiation, on both global and regional scales. The SE U.S. is one of only a few regions not to have warmed during the 20th century and is home to some of the highest summertime levels of biogenic and sulfate aerosols in the U.S. While decreases in aerosol optical depth over the past few decades have likely reduced the cooling effect of aerosols in the region, satellite-derived estimates of aerosol DRE alone may not be sufficient to study long-term DRE trends and the roles played by changing AOD and aerosol optical properties. Appalachian State University (APP) in Boone, NC is home to the only co-located NASA AERONET, NOAA ESRL, and (active) NASA MPLNET sites in the U.S. and is well-positioned to validate satellite-based aerosol retrievals and better constrain background aerosol DRE in regional climate models. As part of the first multi-year `ground truth' DRE study in the SE U.S., Sherman and McComiskey (2017) applied nearly four years of spectral AOD from the APP AERONET site, along with single-scattering albedo(SSA) and asymmetry parameter from the APP NOAA ESRL site, as inputs to the SBDART Radiative Transfer model to calculate seasonal dependence of aerosol DRE and DRE uncertainties at the top-of-atmosphere and at the surface. Clear sky aerosol DRE uncertainty at the TOA (surface) above APP ranges from 0.44 Wm-2 (0.73 Wm-2) for DEC to 0.90 Wm-2 (1.3 Wm-2) for JUN. Expressed as a fraction of seasonal-mean DRE, these uncertainties are 12-20% for all seasons except winter, when they are close to 50%. Use of MODIS or MISR AOD in place of AERONET increases these uncertainties by factors of 2.5 to 5 and DRE uncertainties are dominated by AOD uncertainty for all seasons. The use of SSA from OMI or MISR further increases the DRE uncertainties, especially during the higher AOD summer months, when DRE sensitivity to aerosol type (SSA, g) is highest. Seasonally-dependent sensitivities of aerosol DRE to AOD, SSA, and g above the regionally-representative APP site will be presented, along with current measurement uncertainties from MODIS, MISR, and OMI, to estimate uncertainties in satellite-based estimates of DRE and the degree to which they must be reduced if DRE uncertainty of 1 Wm-2 is to be achieved.

Precision Cleaning and Protection of Coated Optical Components for NIF Small Optics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phelps, Jim

The purpose of this procedure shall be to define the precision cleaning of finished, coated, small optical components for NIF at Lawrence Livermore National Laboratories. The term “small optical components” includes coated optics that are set into simple mounts, as well as coated, un-mounted optics.

Active-optical reflectance sensing evaluated for red and red-edge waveband sensitivity

USDA-ARS?s Scientific Manuscript database

Uncertainty exists with corn (Zea mays L.) N management due to year-to-year variation in crop N need, soil N supply, and N loss from leaching, volatilization, and denitrification. Active-optical reflectance sensing (AORS) has proven effective in some fields for generating N fertilizer recommendation...

Optical radiation measurements: instrumentation and sources of error.

PubMed

Landry, R J; Andersen, F A

1982-07-01

Accurate measurement of optical radiation is required when sources of this radiation are used in biological research. The most difficult measurements of broadband noncoherent optical radiations usually must be performed by a highly trained specialist using sophisticated, complex, and expensive instruments. Presentation of the results of such measurement requires correct use of quantities and units with which many biological researchers are unfamiliar. The measurement process, physical quantities and units, measurement systems with instruments, and sources of error and uncertainties associated with optical radiation measurements are reviewed.

Microscope collision protection apparatus

DOEpatents

DeNure, Charles R.

2001-10-23

A microscope collision protection apparatus for a remote control microscope which protects the optical and associated components from damage in the event of an uncontrolled collision with a specimen, regardless of the specimen size or shape. In a preferred embodiment, the apparatus includes a counterbalanced slide for mounting the microscope's optical components. This slide replaces the rigid mounts on conventional upright microscopes with a precision ball bearing slide. As the specimen contacts an optical component, the contacting force will move the slide and the optical components mounted thereon. This movement will protect the optical and associated components from damage as the movement causes a limit switch to be actuated, thereby stopping all motors responsible for the collision.

Oscillator strengths of the Si II 181 nanometer resonance multiplet

NASA Technical Reports Server (NTRS)

Bergeson, S. D.; Lawler, J. E.

1993-01-01

We report Si II experimental log (gf)-values of -2.38(4) for the 180.801 nm line, of -2.18(4) for the 181.693 nm line, and of -3.29(5) for the 181.745 nm line, where the number in parentheses is the uncertainty in the last digit. The overall uncertainties (about 10 percent) include the 1 sigma random uncertainty (about 6 percent) and an estimate of the systematic uncertainty. The oscillator strengths are determined by combining branching fractions and radiative lifetimes. The branching fractions are measured using standard spectroradiometry on an optically thin source; the radiative lifetimes are measured using time-resolved laser-induced fluorescence.

Exploiting diurnal variations to evaluate the ISCCP-FD flux calculations and radiative-flux-analysis-processed surface observations from BSRN, ARM, and SURFRAD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yuanchong; Long, Charles N.; Rossow, William B.

2010-01-01

Based on monthly-3-hourly and 3-hourly mean surface radiative fluxes and their associated meteorological parameters for 2004 from the International Satellite Cloud Climatology Project-FD (ISCCP-FD) and the Radiative Flux Analysis method-Produced Surface Observations (RFA-PSO) for 15 high-quality-controlled surface stations, operated by the Baseline Surface Radiation Network (BSRN), the Atmospheric Radiation Measurement (ARM) and the National Oceanic and Atmospheric Administration's Surface Radiation budget network (SURFRAD), this work, goes beyond the previous validation for FD against surface observation by introducing the Meteorological Similarity Comparison Method (MSCM) to make a more precise, mutual evaluation of both FD and PSO products. The comparison results inmore » substantial uncertainty reduction and provides reasonable physical explanations for the flux differences. This approach compares fluxes for cases where the atmospheric and surface physical properties (specifically, the input parameters for radiative transfer model) are as close as possible to the values determined at the observational sites by matching the RFA-produced cloud fraction (CF) and/or optical thickness (Tau), etc., or alternatively, by directly changing the model input variables for FD to match PSO values, and using such-produced matched sub-datasets to make more accurate comparisons based on more similar meteorological environments between FD and PSO. The crucial part is the availability of flux-associated meteorological parameters from RFA-PSO, which was only recently made available that makes this work possible. For surface downwelling shortwave(SW) flux (SWdn) and its two components, diffuse (Dif) and direct (Dir), uncertainty for monthly mean is 15, 15 and 17 W/m 2, respectively, smaller than the separately estimated uncertainty values from both FD and PSO. When applying MSCM by reducing their CF difference, the differences can be reduced by a factor of 2. The strength of MSCM is particularly shown in the comparisons of diurnal variations. For clear sky, reducing the FD values of aerosol optical depth (AOD) by 50% to approximately match the PSO values brings all downward SW flux components into substantial agreement. For cloudy scenes, when both CF and Tau are matched to within 0.1 – 0.25 and ~10, respectively, the majority of the SW flux components have nearly-perfect agreement between FD and PSO. The best restriction differences are not zero indicates the influence of other parameters that are not accounted for yet. For longwave (LW) fluxes, general evaluation also confirms uncertainty values for FD and PSO less than separately estimated. When applying MSCM to CF and surface air temperature, the agreement is substantially improved. For downwelling LW diurnal variation comparison, FD shows good agreement with PSO for both RFA-defined or true clear sky but overestimates the amplitude for cloudy sky by 3-7 W/m 2, which may be caused by different sensitivities to cirrus clouds. For upwelling LW diurnal cycle, the situation is reversed; FD now underestimates the diurnal amplitude for all and clear sky but generally agrees for overcast (CF > 0.7). The combined effect of downwelling and upwelling LW fluxes results in FD's underestimates of the diurnal variation of the net-LW-loss for all the scenes by up to 10 W/m 2, although the daily mean net loss is more accurate. Therefore, in terms of amplitude and phase, both FD and PSO seem to have caught correct diurnal variations.« less

Section summary: Uncertainty and design considerations

Treesearch

Stephen Hagen

2013-01-01

Well planned sampling designs and robust approaches to estimating uncertainty are critical components of forest monitoring. The importance of uncertainty estimation increases as deforestation and degradation issues become more closely tied to financing incentives for reducing greenhouse gas emissions in the forest sector. Investors like to know risk and risk is tightly...

Infrared-fiber-optic fire sensor developments - Role of measurement uncertainty in evaluation of background limited range. [in spacecraft safety

NASA Technical Reports Server (NTRS)

Tapphorn, Ralph M.; Kays, Randy; Porter, Alan

1989-01-01

Fire-detector systems based on distributed infrared fiber-sensors have been investigated for potential applications in the aerospace industry. Responsivities to blackbody and flame radiations were measured with various design configurations of an infrared fiber-optic sensor. Signal processing techniques were also investigated, and the results show significant differences in the fire-sensor performance depending on the design configuration. Measurement uncertainties were used to determine the background-limited ranges for the various fire-sensor concepts, and the probability of producing false alarms caused by fluctuations in the background signals were determined using extreme probability theory. The results of the research show that infrared fiber-optic fire sensors are feasible for application on manned spacecraft; however, additional development work will be required to eliminate false alarms caused by high temperature objects such as incandescent lamps.

Accurately Measuring the Color of the Ocean on Earth and from Space: Uncertainties Revisited and A Report from the Community-Led Spectral Absorption Workshop to Update and Revise the NASA Inherent Optical Properties Protocol

NASA Technical Reports Server (NTRS)

Neeley, Aimee Renee

2014-01-01

The color of the ocean (apparent optical properties or AOPs) is determined by the spectral scattering and absorption of light by its dissolved and particulate constituents.The absorption and scattering properties of the water column are the so-called inherent optical properties.

Building Quantitative Hydrologic Storylines from Process-based Models for Managing Water Resources in the U.S. Under Climate-changed Futures

NASA Astrophysics Data System (ADS)

Arnold, J.; Gutmann, E. D.; Clark, M. P.; Nijssen, B.; Vano, J. A.; Addor, N.; Wood, A.; Newman, A. J.; Mizukami, N.; Brekke, L. D.; Rasmussen, R.; Mendoza, P. A.

2016-12-01

Climate change narratives for water-resource applications must represent the change signals contextualized by hydroclimatic process variability and uncertainty at multiple scales. Building narratives of plausible change includes assessing uncertainties across GCM structure, internal climate variability, climate downscaling methods, and hydrologic models. Work with this linked modeling chain has dealt mostly with GCM sampling directed separately to either model fidelity (does the model correctly reproduce the physical processes in the world?) or sensitivity (of different model responses to CO2 forcings) or diversity (of model type, structure, and complexity). This leaves unaddressed any interactions among those measures and with other components in the modeling chain used to identify water-resource vulnerabilities to specific climate threats. However, time-sensitive, real-world vulnerability studies typically cannot accommodate a full uncertainty ensemble across the whole modeling chain, so a gap has opened between current scientific knowledge and most routine applications for climate-changed hydrology. To close that gap, the US Army Corps of Engineers, the Bureau of Reclamation, and the National Center for Atmospheric Research are working on techniques to subsample uncertainties objectively across modeling chain components and to integrate results into quantitative hydrologic storylines of climate-changed futures. Importantly, these quantitative storylines are not drawn from a small sample of models or components. Rather, they stem from the more comprehensive characterization of the full uncertainty space for each component. Equally important from the perspective of water-resource practitioners, these quantitative hydrologic storylines are anchored in actual design and operations decisions potentially affected by climate change. This talk will describe part of our work characterizing variability and uncertainty across modeling chain components and their interactions using newly developed observational data, models and model outputs, and post-processing tools for making the resulting quantitative storylines most useful in practical hydrology applications.

Design of a multi-channel free space optical interconnection component

NASA Astrophysics Data System (ADS)

Jia, Da-Gong; Zhang, Pei-Song; Jing, Wen-Cai; Tan, Jun; Zhang, Hong-Xia; Zhang, Yi-Mo

2008-11-01

A multi-channel free space optical interconnection component, fiber optic rotary joint, was designed using a Dove prism. When the Dove prism is rotated an angle of α around the longitudinal axis, the image rotates an angle of 2 α. The optical interconnection component consists of the signal transmission system, Dove prim and driving mechanism. The planetary gears are used to achieve the speed ratio of 2:1 between the total optical interconnection component and the Dove prism. The C-lenses are employed to couple different optical signals in the signal transmission system. The coupling loss between the receiving fiber of stationary part and the transmitting fiber of rotary part is measured.

The replacement of dry heat in generic reliability assurance requirements for passive optical components

NASA Astrophysics Data System (ADS)

Ren, Xusheng; Qian, Longsheng; Zhang, Guiyan

2005-12-01

According to Generic Reliability Assurance Requirements for Passive Optical Components GR-1221-CORE (Issue 2, January 1999), reliability determination test of different kinds of passive optical components which using in uncontrolled environments is taken. The test condition of High Temperature Storage Test (Dry Test) and Damp Test is in below sheet. Except for humidity condition, all is same. In order to save test time and cost, after a sires of contrast tests, the replacement of Dry Heat is discussed. Controlling the Failure mechanism of dry heat and damp heat of passive optical components, the contrast test of dry heat and damp heat for passive optical components (include DWDM, CWDM, Coupler, Isolator, mini Isolator) is taken. The test result of isolator is listed. Telcordia test not only test the reliability of the passive optical components, but also test the patience of the experimenter. The cost of Telcordia test in money, manpower and material resources, especially in time is heavy burden for the company. After a series of tests, we can find that Damp heat could factually test the reliability of passive optical components, and equipment manufacturer in accord with component manufacture could omit the dry heat test if damp heat test is taken first and passed.

Developing Hydrogeological Site Characterization Strategies based on Human Health Risk

NASA Astrophysics Data System (ADS)

de Barros, F.; Rubin, Y.; Maxwell, R. M.

2013-12-01

In order to provide better sustainable groundwater quality management and minimize the impact of contamination in humans, improved understanding and quantification of the interaction between hydrogeological models, geological site information and human health are needed. Considering the joint influence of these components in the overall human health risk assessment and the corresponding sources of uncertainty aid decision makers to better allocate resources in data acquisition campaigns. This is important to (1) achieve remediation goals in a cost-effective manner, (2) protect human health and (3) keep water supplies clean in order to keep with quality standards. Such task is challenging since a full characterization of the subsurface is unfeasible due to financial and technological constraints. In addition, human exposure and physiological response to contamination are subject to uncertainty and variability. Normally, sampling strategies are developed with the goal of reducing uncertainty, but less often they are developed in the context of their impacts on the overall system uncertainty. Therefore, quantifying the impact from each of these components (hydrogeological, behavioral and physiological) in final human health risk prediction can provide guidance for decision makers to best allocate resources towards minimal prediction uncertainty. In this presentation, a multi-component human health risk-based framework is presented which allows decision makers to set priorities through an information entropy-based visualization tool. Results highlight the role of characteristic length-scales characterizing flow and transport in determining data needs within an integrated hydrogeological-health framework. Conditions where uncertainty reduction in human health risk predictions may benefit from better understanding of the health component, as opposed to a more detailed hydrogeological characterization, are also discussed. Finally, results illustrate how different dose-response models can impact the probability of human health risk exceeding a regulatory threshold.

Erratum: Evidence of b -jet quenching in PbPb collisions at s N N = 2.76 TeV [Phys. Rev. Lett. 113 , 132301 (2014)

DOE PAGES

Chatrchyan, S.

2015-07-10

In our Letter, there was a component of the statistical uncertainty from the simulated PbPb Monte Carlo samples. This uncertainty was not propagated to all of the results. Figures 3 and 4 have been updated to reflect this source of uncertainty. In this case, the statistical uncertainties remain smaller than the systematic uncertainties in all cases such that the conclusions of the Letter are unaltered.

Experiments on Frequency Dependence of the Deflection of Light in Yang-Mills Gravity

NASA Astrophysics Data System (ADS)

Hao, Yun; Zhu, Yiyi; Hsu, Jong-Ping

2018-01-01

In Yang-Mills gravity based on flat space-time, the eikonal equation for a light ray is derived from the modified Maxwell's wave equations in the geometric-optics limit. One obtains a Hamilton-Jacobi type equation, GLµv∂µΨ∂vΨ = 0 with an effective Riemannian metric tensor GLµv. According to Yang-Mills gravity, light rays (and macroscopic objects) move as if they were in an effective curved space-time with a metric tensor. The deflection angle of a light ray by the sun is about 1.53″ for experiments with optical frequencies ≈ 1014Hz. It is roughly 12% smaller than the usual value 1.75″. However, the experimental data in the past 100 years for the deflection of light by the sun in optical frequencies have uncertainties of (10-20)% due to large systematic errors. If one does not take the geometric-optics limit, one has the equation, GLµv[∂µΨ∂vΨcosΨ+ (∂µ∂vΨ)sinΨ] = 0, which suggests that the deflection angle could be frequency-dependent, according to Yang-Mills gravity. Nowadays, one has very accurate data in the radio frequencies ≈ 109Hz with uncertainties less than 0.1%. Thus, one can test this suggestion by using frequencies ≈ 1012 Hz, which could have a small uncertainty 0.1% due to the absence of systematic errors in the very long baseline interferometry.

Temperature effects on wavelength calibration of the optical spectrum analyzer

NASA Astrophysics Data System (ADS)

Mongkonsatit, Kittiphong; Ranusawud, Monludee; Srikham, Sitthichai; Bhatranand, Apichai; Jiraraksopakun, Yuttapong

2018-03-01

This paper presents the investigation of the temperature effects on wavelength calibration of an optical spectrum analyzer or OSA. The characteristics of wavelength dependence on temperatures are described and demonstrated under the guidance of the IEC 62129-1:2006, the international standard for the Calibration of wavelength/optical frequency measurement instruments - Part 1: Optical spectrum analyzer. Three distributed-feedback lasers emit lights with wavelengths of 1310 nm, 1550 nm, and 1600 nm were used as light sources in this work. Each light was split by a 1 x 2 fiber splitter whereas one end was connected to a standard wavelength meter and the other to an under-test OSA. Two Experiment setups were arranged for the analysis of the wavelength reading deviations between a standard wavelength meter and an OSA under a variety of circumstances of different temperatures and humidity conditions. The experimental results showed that, for wavelengths of 1550 nm and 1600 nm, the wavelength deviations were proportional to the value of temperature with the minimum and maximum of -0.015 and 0.030 nm, respectively. While the deviations of 1310 nm wavelength did not change much with the temperature as they were in the range of -0.003 nm to 0.010 nm. The measurement uncertainty was also evaluated according to the IEC 62129-1:2006. The main contribution of measurement uncertainty was caused by the wavelength deviation. The uncertainty of measurement in this study is 0.023 nm with coverage factor, k = 2.

Light fluence dosimetry in lung-simulating cavities

NASA Astrophysics Data System (ADS)

Zhu, Timothy C.; Kim, Michele M.; Padawer, Jonah; Dimofte, Andreea; Potasek, Mary; Beeson, Karl; Parilov, Evgueni

2018-02-01

Accurate light dosimery is critical to ensure consistent outcome for pleural photodynamic therapy (pPDT). Ellipsoid shaped cavities with different sizes surrounded by turbid medium are used to simulate the intracavity lung geometry. An isotropic light source is introduced and surrounded by turbid media. Direct measurements of light fluence rate were compared to Monte Carlo simulated values on the surface of the cavities for various optical properties. The primary component of the light was determined by measurements performed in air in the same geometry. The scattered component was found by submerging the air-filled cavity in scattering media (Intralipid) and absorbent media (ink). The light source was located centrally with the azimuthal angle, but placed in two locations (vertically centered and 2 cm below the center) for measurements. Light fluence rate was measured using isotropic detectors placed at various angles on the ellipsoid surface. The measurements and simulations show that the scattered dose is uniform along the surface of the intracavity ellipsoid geometries in turbid media. One can express the light fluence rate empirically as φ =4S/As*Rd/(1- Rd), where Rd is the diffuse reflectance, As is the surface area, and S is the source power. The measurements agree with this empirical formula to within an uncertainty of 10% for the range of optical properties studied. GPU voxel-based Monte-Carlo simulation is performed to compare with measured results. This empirical formula can be applied to arbitrary geometries, such as the pleural or intraperitoneal cavity.

Accounting for Epistemic Uncertainty in Mission Supportability Assessment: A Necessary Step in Understanding Risk and Logistics Requirements

NASA Technical Reports Server (NTRS)

Owens, Andrew; De Weck, Olivier L.; Stromgren, Chel; Goodliff, Kandyce; Cirillo, William

2017-01-01

Future crewed missions to Mars present a maintenance logistics challenge that is unprecedented in human spaceflight. Mission endurance – defined as the time between resupply opportunities – will be significantly longer than previous missions, and therefore logistics planning horizons are longer and the impact of uncertainty is magnified. Maintenance logistics forecasting typically assumes that component failure rates are deterministically known and uses them to represent aleatory uncertainty, or uncertainty that is inherent to the process being examined. However, failure rates cannot be directly measured; rather, they are estimated based on similarity to other components or statistical analysis of observed failures. As a result, epistemic uncertainty – that is, uncertainty in knowledge of the process – exists in failure rate estimates that must be accounted for. Analyses that neglect epistemic uncertainty tend to significantly underestimate risk. Epistemic uncertainty can be reduced via operational experience; for example, the International Space Station (ISS) failure rate estimates are refined using a Bayesian update process. However, design changes may re-introduce epistemic uncertainty. Thus, there is a tradeoff between changing a design to reduce failure rates and operating a fixed design to reduce uncertainty. This paper examines the impact of epistemic uncertainty on maintenance logistics requirements for future Mars missions, using data from the ISS Environmental Control and Life Support System (ECLS) as a baseline for a case study. Sensitivity analyses are performed to investigate the impact of variations in failure rate estimates and epistemic uncertainty on spares mass. The results of these analyses and their implications for future system design and mission planning are discussed.

Evaluation of the uncertainty in an EBT3 film dosimetry system utilizing net optical density.

PubMed

Marroquin, Elsa Y León; Herrera González, José A; Camacho López, Miguel A; Barajas, José E Villarreal; García-Garduño, Olivia A

2016-09-08

Radiochromic film has become an important tool to verify dose distributions for intensity-modulated radiotherapy (IMRT) and quality assurance (QA) procedures. A new radiochromic film model, EBT3, has recently become available, whose composition and thickness of the sensitive layer are the same as those of previous EBT2 films. However, a matte polyester layer was added to EBT3 to prevent the formation of Newton's rings. Furthermore, the symmetrical design of EBT3 allows the user to eliminate side-orientation dependence. This film and the flatbed scanner, Epson Perfection V750, form a dosimetry system whose intrinsic characteristics were studied in this work. In addition, uncertainties associated with these intrinsic characteristics and the total uncertainty of the dosimetry system were determined. The analysis of the response of the radiochromic film (net optical density) and the fitting of the experimental data to a potential function yielded an uncertainty of 2.6%, 4.3%, and 4.1% for the red, green, and blue channels, respectively. In this work, the dosimetry system presents an uncertainty in resolving the dose of 1.8% for doses greater than 0.8 Gy and less than 6 Gy for red channel. The films irradiated between 0 and 120 Gy show differences in the response when scanned in portrait or landscape mode; less uncertainty was found when using the portrait mode. The response of the film depended on the position on the bed of the scanner, contributing an uncertainty of 2% for the red, 3% for the green, and 4.5% for the blue when placing the film around the center of the bed of scanner. Furthermore, the uniformity and reproducibility radiochromic film and reproducibility of the response of the scanner contribute less than 1% to the overall uncertainty in dose. Finally, the total dose uncertainty was 3.2%, 4.9%, and 5.2% for red, green, and blue channels, respectively. The above uncertainty values were obtained by mini-mizing the contribution to the total dose uncertainty of the film orientation and film homogeneity. © 2016 The Authors.

Evaluation of the uncertainty in an EBT3 film dosimetry system utilizing net optical density

PubMed Central

Marroquin, Elsa Y. León; Herrera González, José A.; Camacho López, Miguel A.; Barajas, José E. Villarreal

2016-01-01

Radiochromic film has become an important tool to verify dose distributions for intensity‐modulated radiotherapy (IMRT) and quality assurance (QA) procedures. A new radiochromic film model, EBT3, has recently become available, whose composition and thickness of the sensitive layer are the same as those of previous EBT2 films. However, a matte polyester layer was added to EBT3 to prevent the formation of Newton's rings. Furthermore, the symmetrical design of EBT3 allows the user to eliminate side‐orientation dependence. This film and the flatbed scanner, Epson Perfection V750, form a dosimetry system whose intrinsic characteristics were studied in this work. In addition, uncertainties associated with these intrinsic characteristics and the total uncertainty of the dosimetry system were determined. The analysis of the response of the radiochromic film (net optical density) and the fitting of the experimental data to a potential function yielded an uncertainty of 2.6%, 4.3%, and 4.1% for the red, green, and blue channels, respectively. In this work, the dosimetry system presents an uncertainty in resolving the dose of 1.8% for doses greater than 0.8 Gy and less than 6 Gy for red channel. The films irradiated between 0 and 120 Gy show differences in the response when scanned in portrait or landscape mode; less uncertainty was found when using the portrait mode. The response of the film depended on the position on the bed of the scanner, contributing an uncertainty of 2% for the red, 3% for the green, and 4.5% for the blue when placing the film around the center of the bed of scanner. Furthermore, the uniformity and reproducibility radiochromic film and reproducibility of the response of the scanner contribute less than 1% to the overall uncertainty in dose. Finally, the total dose uncertainty was 3.2%, 4.9%, and 5.2% for red, green, and blue channels, respectively. The above uncertainty values were obtained by minimizing the contribution to the total dose uncertainty of the film orientation and film homogeneity. PACS number(s): 87.53.Bn PMID:27685125

Uncertainty of passive imager cloud retrievals to instrument radiometry and model assumptions: Examples from MODIS Collection 6

NASA Astrophysics Data System (ADS)

Platnick, S.; Wind, G.; Amarasinghe, N.; Arnold, G. T.; Zhang, Z.; Meyer, K.; King, M. D.

2013-12-01

The optical and microphysical structure of clouds is of fundamental importance for understanding a variety of cloud radiation and precipitation processes. With the advent of MODIS on the NASA EOS Terra and Aqua platforms, simultaneous global/daily 1km retrievals of cloud optical thickness (COT) and effective particle radius (CER) are provided, as well as the derived water path (WP). The cloud product (MOD06/MYD06 for MODIS Terra and Aqua, respectively) provides separate retrieval datasets for various two-channel retrievals, typically a VIS/NIR channel paired with a 1.6, 2.1, and 3.7 μm spectral channel. The MOD06 forward model is derived from a homogeneous plane-parallel cloud. In Collection 5 processing (completed in 2007 with a modified Collection 5.1 completed in 2010), pixel-level retrieval uncertainties were calculated for the following non-3-D error sources: radiometry, surface spectral albedo, and atmospheric corrections associated with model analysis uncertainties (water vapor only). The latter error source includes error correlation across the retrieval spectral channels. Estimates of uncertainty in 1° aggregated (Level-3) means were also provided assuming unity correlation between error sources for all pixels in a grid for a single day, and zero correlation of error sources from one day to the next. In Collection 6 (expected to begin in late summer 2013) we expanded the uncertainty analysis to include: (a) scene-dependent calibration uncertainty that depends on new band and detector-specific Level 1B uncertainties, (b) new model error sources derived from the look-up tables which includes sensitivities associated with wind direction over the ocean and uncertainties in liquid water and ice effective variance, (c) thermal emission uncertainties in the 3.7 μm band associated with cloud and surface temperatures that are needed to extract reflected solar radiation from the total radiance signal, (d) uncertainty in the solar spectral irradiance at 3.7 μm, and (e) addition of stratospheric ozone uncertainty in visible atmospheric corrections. A summary of the approach and example Collection 6 results will be shown.

An overview of methods to identify and manage uncertainty for modelling problems in the water-environment-agriculture cross-sector

DOE PAGES

Jakeman, Anthony J.; Jakeman, John Davis

2018-03-14

Uncertainty pervades the representation of systems in the water–environment–agriculture cross-sector. Successful methods to address uncertainties have largely focused on standard mathematical formulations of biophysical processes in a single sector, such as partial or ordinary differential equations. More attention to integrated models of such systems is warranted. Model components representing the different sectors of an integrated model can have less standard, and different, formulations to one another, as well as different levels of epistemic knowledge and data informativeness. Thus, uncertainty is not only pervasive but also crosses boundaries and propagates between system components. Uncertainty assessment (UA) cries out for more eclecticmore » treatment in these circumstances, some of it being more qualitative and empirical. Here in this paper, we discuss the various sources of uncertainty in such a cross-sectoral setting and ways to assess and manage them. We have outlined a fast-growing set of methodologies, particularly in the computational mathematics literature on uncertainty quantification (UQ), that seem highly pertinent for uncertainty assessment. There appears to be considerable scope for advancing UA by integrating relevant UQ techniques into cross-sectoral problem applications. Of course this will entail considerable collaboration between domain specialists who often take first ownership of the problem and computational methods experts.« less

An overview of methods to identify and manage uncertainty for modelling problems in the water-environment-agriculture cross-sector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jakeman, Anthony J.; Jakeman, John Davis

Uncertainty pervades the representation of systems in the water–environment–agriculture cross-sector. Successful methods to address uncertainties have largely focused on standard mathematical formulations of biophysical processes in a single sector, such as partial or ordinary differential equations. More attention to integrated models of such systems is warranted. Model components representing the different sectors of an integrated model can have less standard, and different, formulations to one another, as well as different levels of epistemic knowledge and data informativeness. Thus, uncertainty is not only pervasive but also crosses boundaries and propagates between system components. Uncertainty assessment (UA) cries out for more eclecticmore » treatment in these circumstances, some of it being more qualitative and empirical. Here in this paper, we discuss the various sources of uncertainty in such a cross-sectoral setting and ways to assess and manage them. We have outlined a fast-growing set of methodologies, particularly in the computational mathematics literature on uncertainty quantification (UQ), that seem highly pertinent for uncertainty assessment. There appears to be considerable scope for advancing UA by integrating relevant UQ techniques into cross-sectoral problem applications. Of course this will entail considerable collaboration between domain specialists who often take first ownership of the problem and computational methods experts.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grantham, K; Santanam, L; Goddu, S

Purpose: We retrospectively evaluate the dosimetric impact of a 3.5% range uncertainty on CTV coverage and normal organ toxicity for a cohort of brain patients. Methods: Twenty treatment plans involving 20 brain cancer patients treated with Mevions S250 were reviewed. Forty uncertain plans were made by changing the ranges in original plans by ±3.5% while keeping all devices unchanged. Fidelity to the original plans was evaluated with gamma index. Changes in generalized equivalent uniform dose (gEUD) were reported for the following structures: CTV coverage, brainstem, optic chiasm, and optic nerves. Comparisons were made by plotting the relevant endpoints from themore » uncertain plans as a function of the same endpoints from the original clinical plan. Results: Gamma-index analysis resulted in a 50% pass rate of the uncertain plans using a 90% passing rate and 3%/3mm criterion. A 9.5% decrease in the slope of gEUD plot for the CTV was observed for the 3.5% downward range shift. However, the change in slope did not result in a gEUD change greater than 1.1% for the CTV. The slopes of the gEUD plots for normal structures increased by 3.1% 3.9% 2.4% and 0.2% for the chiasm, brainstem, left optic nerve and right optic nerve respectively. The maximum deviation from the gEUD of the clinical plan for normal structures was: 64% in the chiasm, 31% for the brainstem, and 19% for both optic nerves. Conclusion: A retrospective review shows moderate radiobiological impact of range uncertainty in passively scattered proton therapy with sporadic catastrophe. The linear regression analysis on the statistical data indicates a systematic deviation of gEUD from treatment planning in the light of range uncertainty.« less

Experimental uncertainty survey and assessment. [Space Shuttle Main Engine testing

NASA Technical Reports Server (NTRS)

Coleman, Hugh W.

1992-01-01

An uncertainty analysis and assessment of the specific impulse determination during Space Shuttle Main Engine testing is reported. It is concluded that in planning and designing tests and in interpreting the results of tests, the bias and precision components of experimental uncertainty should be considered separately. Recommendations for future research efforts are presented.

Laser beam soldering of micro-optical components

NASA Astrophysics Data System (ADS)

Eberhardt, R.

2003-05-01

MOTIVATION Ongoing miniaturisation and higher requirements within optical assemblies and the processing of temperature sensitive components demands for innovative selective joining techniques. So far adhesive bonding has primarily been used to assemble and adjust hybrid micro optical systems. However, the properties of the organic polymers used for the adhesives limit the application of these systems. In fields of telecommunication and lithography, an enhancement of existing joining techniques is necessary to improve properties like humidity resistance, laserstability, UV-stability, thermal cycle reliability and life time reliability. Against this background laser beam soldering of optical components is a reasonable joining technology alternative. Properties like: - time and area restricted energy input - energy input can be controlled by the process temperature - direct and indirect heating of the components is possible - no mechanical contact between joining tool and components give good conditions to meet the requirements on a joining technology for sensitive optical components. Additionally to the laser soldering head, for the assembly of optical components it is necessary to include positioning units to adjust the position of the components with high accuracy before joining. Furthermore, suitable measurement methods to characterize the soldered assemblies (for instance in terms of position tolerances) need to be developed.

Indexing Mount For Rotation Of Optical Component

NASA Technical Reports Server (NTRS)

Reichle, Donald J., Jr.; Barnes, Norman P.

1993-01-01

Indexing mount for polarizer, wave plate, birefringent plate, or other optical component facilitates rotation of component to one or more preset angles. Includes hexagonal nut holding polarizer or other optical component. Ball bearing loaded by screw engages notch on cylindrical extension of nut engaging bracket. Time-consuming and tedious angular adjustment unnecessary: component turned quickly and easily, by hand or by use of wrench, to preset angular positions maintained by simple ball-detent mechanism.

A final look at LDEF electro-optic systems components

NASA Technical Reports Server (NTRS)

Blue, M. D.

1995-01-01

Postrecovery characteristics of LDEF electro-optic components from the GTRI tray are compared with their prelaunch characteristics and with the characteristics of similar components from related experiments. Components considered here include lasers, light-emitting diodes, semiconducting radiation detectors and arrays, optical substrates, filters, and mirrors, and specialized coatings. Our understanding of the physical effects resulting from low earth orbit are described, and guidelines and recommendations for component and materials choices are presented.

Repeated decompositions reveal the stability of infomax decomposition of fMRI data

PubMed Central

Duann, Jeng-Ren; Jung, Tzyy-Ping; Sejnowski, Terrence J.; Makeig, Scott

2010-01-01

In this study, we decomposed 12 fMRI data sets from six subjects each 101 times using the infomax algorithm. The first decomposition was taken as a reference decomposition; the others were used to form a component matrix of 100 by 100 components. Equivalence relations between components in this matrix, defined as maximum spatial correlations to the components of the reference decomposition, were found by the Hungarian sorting method and used to form 100 equivalence classes for each data set. We then tested the reproducibility of the matched components in the equivalence classes using uncertainty measures based on component distributions, time courses, and ROC curves. Infomax ICA rarely failed to derive nearly the same components in different decompositions. Very few components per data set were poorly reproduced, even using vector angle uncertainty measures stricter than correlation and detection theory measures. PMID:17281453

A Peep into the Uncertainty-Complexity-Relevance Modeling Trilemma through Global Sensitivity and Uncertainty Analysis

NASA Astrophysics Data System (ADS)

Munoz-Carpena, R.; Muller, S. J.; Chu, M.; Kiker, G. A.; Perz, S. G.

2014-12-01

Model Model complexity resulting from the need to integrate environmental system components cannot be understated. In particular, additional emphasis is urgently needed on rational approaches to guide decision making through uncertainties surrounding the integrated system across decision-relevant scales. However, in spite of the difficulties that the consideration of modeling uncertainty represent for the decision process, it should not be avoided or the value and science behind the models will be undermined. These two issues; i.e., the need for coupled models that can answer the pertinent questions and the need for models that do so with sufficient certainty, are the key indicators of a model's relevance. Model relevance is inextricably linked with model complexity. Although model complexity has advanced greatly in recent years there has been little work to rigorously characterize the threshold of relevance in integrated and complex models. Formally assessing the relevance of the model in the face of increasing complexity would be valuable because there is growing unease among developers and users of complex models about the cumulative effects of various sources of uncertainty on model outputs. In particular, this issue has prompted doubt over whether the considerable effort going into further elaborating complex models will in fact yield the expected payback. New approaches have been proposed recently to evaluate the uncertainty-complexity-relevance modeling trilemma (Muller, Muñoz-Carpena and Kiker, 2011) by incorporating state-of-the-art global sensitivity and uncertainty analysis (GSA/UA) in every step of the model development so as to quantify not only the uncertainty introduced by the addition of new environmental components, but the effect that these new components have over existing components (interactions, non-linear responses). Outputs from the analysis can also be used to quantify system resilience (stability, alternative states, thresholds or tipping points) in the face of environmental and anthropogenic change (Perz, Muñoz-Carpena, Kiker and Holt, 2013), and through MonteCarlo mapping potential management activities over the most important factors or processes to influence the system towards behavioral (desirable) outcomes (Chu-Agor, Muñoz-Carpena et al., 2012).

Optical Distance Measurement Device And Method Thereof

DOEpatents

Bowers, Mark W.

2004-06-15

A system and method of efficiently obtaining distance measurements of a target by scanning the target. An optical beam is provided by a light source and modulated by a frequency source. The modulated optical beam is transmitted to an acousto-optical deflector capable of changing the angle of the optical beam in a predetermined manner to produce an output for scanning the target. In operation, reflected or diffused light from the target may be received by a detector and transmitted to a controller configured to calculate the distance to the target as well as the measurement uncertainty in calculating the distance to the target.

Characterization of transimpedance amplifier as optical to electrical converter on designing optical instrumentation

NASA Astrophysics Data System (ADS)

Hanto, D.; Ula, R. K.

2017-05-01

Optical to electrical converter is the main components for designing of the optical instrumentations. In addition, this component is also used as signal conditioning. This component usually consists of a photo detector and amplifier. In this paper, characteristics of commercial amplifiers from Thorlabs PDA50B-EC has been observed. The experiment was conducted by diode laser with power of -5 dBm and wavelength 1310 nm; the optical attenuator to vary optical power from 0 to 60 dB, optical to electrical converter from Thorlabs Amplifier PDA50B-EC; multimode optical fiber to guide the laser; and digital voltmeter to measure the output of converter. The results of the characterization indicate that each channel amplification has a non-linear correlation between optical and electrical parameter; optical conversion measurement range of 20-23 dB to full scale; and different measurement coverage area. If this converter will be used as a part component of optical instrumentation so it should be adjusted suitably with the optical power source. Then, because of the correlation equation is not linear so calculation to determine the interpretation also should be considered in addition to the transfer function of the optical sensor.

Temperature-strain discrimination in distributed optical fiber sensing using phase-sensitive optical time-domain reflectometry.

PubMed

Lu, Xin; Soto, Marcelo A; Thévenaz, Luc

2017-07-10

A method based on coherent Rayleigh scattering distinctly evaluating temperature and strain is proposed and experimentally demonstrated for distributed optical fiber sensing. Combining conventional phase-sensitive optical time-domain domain reflectometry (ϕOTDR) and ϕOTDR-based birefringence measurements, independent distributed temperature and strain profiles are obtained along a polarization-maintaining fiber. A theoretical analysis, supported by experimental data, indicates that the proposed system for temperature-strain discrimination is intrinsically better conditioned than an equivalent existing approach that combines classical Brillouin sensing with Brillouin dynamic gratings. This is due to the higher sensitivity of coherent Rayleigh scatting compared to Brillouin scattering, thus offering better performance and lower temperature-strain uncertainties in the discrimination. Compared to the Brillouin-based approach, the ϕOTDR-based system here proposed requires access to only one fiber-end, and a much simpler experimental layout. Experimental results validate the full discrimination of temperature and strain along a 100 m-long elliptical-core polarization-maintaining fiber with measurement uncertainties of ~40 mK and ~0.5 με, respectively. These values agree very well with the theoretically expected measurand resolutions.

Ozone Observations by the Gas and Aerosol Measurement Sensor during SOLVE II

NASA Technical Reports Server (NTRS)

Pitts, M. C.; Thomason, L. W.; Zawodny, J. M.; Wenny, B. N.; Livingston, J. M.; Russell, P. B.; Yee, J.-H.; Swartz, W. H.; Shetter, R. E.

2006-01-01

The Gas and Aerosol Measurement Sensor (GAMS) was deployed aboard the NASA DC-8 aircraft during the second SAGE III Ozone Loss and Validation Experiment (SOLVE II). GAMS acquired line-of-sight (LOS) direct solar irradiance spectra during the sunlit portions of ten science flights of the DC-8 between 12 January and 4 February 2003. Differential line-of-sight (DLOS) optical depth spectra are produced from the GAMS raw solar irradiance spectra. Then, DLOS ozone number densities are retrieved from the GAMS spectra using a multiple linear regression spectral fitting technique. Both the DLOS optical depth spectra and retrieved ozone data are compared with coincident measurements from two other solar instruments aboard the DC-8 platform to demonstrate the robustness and stability of the GAMS data. The GAMS ozone measurements are then utilized to evaluate the quality of the Wulf band ozone cross sections, a critical component of the SAGE III aerosol, water vapor, and temperature/pressure retrievals. Results suggest the ozone cross section compilation of Shettle and Anderson currently used operationally in SAGE III data processing may be in error by as much as 10-20% in theWulf bands, and their lack of reported temperature dependence is a significant deficiency. A second, more recent, cross section database compiled for the SCIAMACHY satellite mission appears to be of much better quality in the Wulf bands, but still may have errors as large as 5% near the Wulf band absorption peaks, which is slightly larger than their stated uncertainty. Additional laboratory measurements of the Wulf band cross sections should be pursued to further reduce their uncertainty and better quantify their temperature dependence.

Prism Window for Optical Alignment

NASA Technical Reports Server (NTRS)

Tang, Hong

2008-01-01

A prism window has been devised for use, with an autocollimator, in aligning optical components that are (1) required to be oriented parallel to each other and/or at a specified angle of incidence with respect to a common optical path and (2) mounted at different positions along the common optical path. The prism window can also be used to align a single optical component at a specified angle of incidence. Prism windows could be generally useful for orienting optical components in manufacture of optical instruments. "Prism window" denotes an application-specific unit comprising two beam-splitter windows that are bonded together at an angle chosen to obtain the specified angle of incidence.

International Instrumentation Symposium, 34th, Albuquerque, NM, May 2-6, 1988, Proceedings

NASA Astrophysics Data System (ADS)

Various papers on aerospace instrumentation are presented. The general topics addressed include: blast and shock, wind tunnel instrumentations and controls, digital/optical sensors, software design/development, special test facilities, fiber optic techniques, electro/fiber optical measurement systems, measurement uncertainty, real time systems, pressure. Also discussed are: flight test and avionics instrumentation, data acquisition techniques, computer applications, thermal force and displacement, science and government, modeling techniques, reentry vehicle testing, strain and pressure.

Probabilistic evaluation of uncertainties and risks in aerospace components

NASA Technical Reports Server (NTRS)

Shah, A. R.; Shiao, M. C.; Nagpal, V. K.; Chamis, C. C.

1992-01-01

A methodology is presented for the computational simulation of primitive variable uncertainties, and attention is given to the simulation of specific aerospace components. Specific examples treated encompass a probabilistic material behavior model, as well as static, dynamic, and fatigue/damage analyses of a turbine blade in a mistuned bladed rotor in the SSME turbopumps. An account is given of the use of the NESSES probabilistic FEM analysis CFD code.

Multiple Damage Progression Paths in Model-Based Prognostics

NASA Technical Reports Server (NTRS)

Daigle, Matthew; Goebel, Kai Frank

2011-01-01

Model-based prognostics approaches employ domain knowledge about a system, its components, and how they fail through the use of physics-based models. Component wear is driven by several different degradation phenomena, each resulting in their own damage progression path, overlapping to contribute to the overall degradation of the component. We develop a model-based prognostics methodology using particle filters, in which the problem of characterizing multiple damage progression paths is cast as a joint state-parameter estimation problem. The estimate is represented as a probability distribution, allowing the prediction of end of life and remaining useful life within a probabilistic framework that supports uncertainty management. We also develop a novel variance control mechanism that maintains an uncertainty bound around the hidden parameters to limit the amount of estimation uncertainty and, consequently, reduce prediction uncertainty. We construct a detailed physics-based model of a centrifugal pump, to which we apply our model-based prognostics algorithms. We illustrate the operation of the prognostic solution with a number of simulation-based experiments and demonstrate the performance of the chosen approach when multiple damage mechanisms are active

Systematic evaluation of an atomic clock at 2 × 10−18 total uncertainty

PubMed Central

Nicholson, T.L.; Campbell, S.L.; Hutson, R.B.; Marti, G.E.; Bloom, B.J.; McNally, R.L.; Zhang, W.; Barrett, M.D.; Safronova, M.S.; Strouse, G.F.; Tew, W.L.; Ye, J.

2015-01-01

The pursuit of better atomic clocks has advanced many research areas, providing better quantum state control, new insights in quantum science, tighter limits on fundamental constant variation and improved tests of relativity. The record for the best stability and accuracy is currently held by optical lattice clocks. Here we take an important step towards realizing the full potential of a many-particle clock with a state-of-the-art stable laser. Our 87Sr optical lattice clock now achieves fractional stability of 2.2 × 10−16 at 1 s. With this improved stability, we perform a new accuracy evaluation of our clock, reducing many systematic uncertainties that limited our previous measurements, such as those in the lattice ac Stark shift, the atoms' thermal environment and the atomic response to room-temperature blackbody radiation. Our combined measurements have reduced the total uncertainty of the JILA Sr clock to 2.1 × 10−18 in fractional frequency units. PMID:25898253

Wavelength modulation diode laser absorption spectroscopy for high-pressure gas sensing

NASA Astrophysics Data System (ADS)

Sun, K.; Chao, X.; Sur, R.; Jeffries, J. B.; Hanson, R. K.

2013-03-01

A general model for 1 f-normalized wavelength modulation absorption spectroscopy with nf detection (i.e., WMS- nf) is presented that considers the performance of injection-current-tuned diode lasers and the reflective interference produced by other optical components on the line-of-sight (LOS) transmission intensity. This model explores the optimization of sensitive detection of optical absorption by species with structured spectra at elevated pressures. Predictions have been validated by comparison with measurements of the 1 f-normalized WMS- nf (for n = 2-6) lineshape of the R(11) transition in the 1st overtone band of CO near 2.3 μm at four different pressures ranging from 5 to 20 atm, all at room temperature. The CO mole fractions measured by 1 f-normalized WMS-2 f, 3 f, and 4 f techniques agree with calibrated mixtures within 2.0 %. At conditions where absorption features are significantly broadened and large modulation depths are required, uncertainties in the WMS background signals due to reflective interference in the optical path can produce significant error in gas mole fraction measurements by 1 f-normalized WMS-2 f. However, such potential errors can be greatly reduced by using the higher harmonics, i.e., 1 f-normalized WMS- nf with n > 2. In addition, less interference from pressure-broadened neighboring transitions has been observed for WMS with higher harmonics than for WMS-2 f.

Number-phase minimum-uncertainty state with reduced number uncertainty in a Kerr nonlinear interferometer

NASA Astrophysics Data System (ADS)

Kitagawa, M.; Yamamoto, Y.

1987-11-01

An alternative scheme for generating amplitude-squeezed states of photons based on unitary evolution which can properly be described by quantum mechanics is presented. This scheme is a nonlinear Mach-Zehnder interferometer containing an optical Kerr medium. The quasi-probability density (QPD) and photon-number distribution of the output field are calculated, and it is demonstrated that the reduced photon-number uncertainty and enhanced phase uncertainty maintain the minimum-uncertainty product. A self-phase-modulation of the single-mode quantized field in the Kerr medium is described based on localized operators. The spatial evolution of the state is demonstrated by QPD in the Schroedinger picture. It is shown that photon-number variance can be reduced to a level far below the limit for an ordinary squeezed state, and that the state prepared using this scheme remains a number-phase minimum-uncertainty state until the maximum reduction of number fluctuations is surpassed.

The current development status of the Orbiting Carbon Observatory (OCO) instrument optical design

NASA Technical Reports Server (NTRS)

Haring, Robert; Sutin, Brian; Crisp, David; Pollock, Randy; Sundstrand, Hamilton

2005-01-01

The status of the OCO instrument optical design is presented in this paper. The optical bench assembly comprises three cooled grating spectrometers coupled to an all-reflective telescope/relay system. Dichroic beam splitters are used to separate the light from a common telescope into the three spectral bands. The three bore sighted spectrometers allow the total column CO2 absorption path to be corrected for optical path and surface pressure uncertainties, aerosols, and water vapor. The design of the instrument is based on classic flight proven technologies.

Optical Frequency Synthesizer for Precision Spectroscopy

NASA Astrophysics Data System (ADS)

Holzwarth, R.; Udem, Th.; Hänsch, T. W.; Knight, J. C.; Wadsworth, W. J.; Russell, P. St. J.

2000-09-01

We have used the frequency comb generated by a femtosecond mode-locked laser and broadened to more than an optical octave in a photonic crystal fiber to realize a frequency chain that links a 10 MHz radio frequency reference phase-coherently in one step to the optical region. By comparison with a similar frequency chain we set an upper limit for the uncertainty of this new approach to 5.1×10-16. This opens the door for measurement and synthesis of virtually any optical frequency and is ready to revolutionize frequency metrology.

Overview of microoptics: Past, present, and future

NASA Technical Reports Server (NTRS)

Veldkamp, Wilfrid B.

1993-01-01

Through advances in semiconductor miniaturization technology, microrelief patterns, with characteristic dimensions as small as the wavelength of light, can now be mass reproduced to form high-quality and low-cost optical components. In a unique example of technology transfer, from electronics to optics, this capability is allowing optics designers to create innovative optical components that promise to solve key problems in optical sensors, optical communication channels, and optical processors.

A method to estimate the effect of deformable image registration uncertainties on daily dose mapping

PubMed Central

Murphy, Martin J.; Salguero, Francisco J.; Siebers, Jeffrey V.; Staub, David; Vaman, Constantin

2012-01-01

Purpose: To develop a statistical sampling procedure for spatially-correlated uncertainties in deformable image registration and then use it to demonstrate their effect on daily dose mapping. Methods: Sequential daily CT studies are acquired to map anatomical variations prior to fractionated external beam radiotherapy. The CTs are deformably registered to the planning CT to obtain displacement vector fields (DVFs). The DVFs are used to accumulate the dose delivered each day onto the planning CT. Each DVF has spatially-correlated uncertainties associated with it. Principal components analysis (PCA) is applied to measured DVF error maps to produce decorrelated principal component modes of the errors. The modes are sampled independently and reconstructed to produce synthetic registration error maps. The synthetic error maps are convolved with dose mapped via deformable registration to model the resulting uncertainty in the dose mapping. The results are compared to the dose mapping uncertainty that would result from uncorrelated DVF errors that vary randomly from voxel to voxel. Results: The error sampling method is shown to produce synthetic DVF error maps that are statistically indistinguishable from the observed error maps. Spatially-correlated DVF uncertainties modeled by our procedure produce patterns of dose mapping error that are different from that due to randomly distributed uncertainties. Conclusions: Deformable image registration uncertainties have complex spatial distributions. The authors have developed and tested a method to decorrelate the spatial uncertainties and make statistical samples of highly correlated error maps. The sample error maps can be used to investigate the effect of DVF uncertainties on daily dose mapping via deformable image registration. An initial demonstration of this methodology shows that dose mapping uncertainties can be sensitive to spatial patterns in the DVF uncertainties. PMID:22320766

Additive manufacturing of optical components

NASA Astrophysics Data System (ADS)

Heinrich, Andreas; Rank, Manuel; Maillard, Philippe; Suckow, Anne; Bauckhage, Yannick; Rößler, Patrick; Lang, Johannes; Shariff, Fatin; Pekrul, Sven

2016-08-01

The development of additive manufacturing methods has enlarged rapidly in recent years. Thereby, the work mainly focuses on the realization of mechanical components, but the additive manufacturing technology offers a high potential in the field of optics as well. Owing to new design possibilities, completely new solutions are possible. This article briefly reviews and compares the most important additive manufacturing methods for polymer optics. Additionally, it points out the characteristics of additive manufactured polymer optics. Thereby, surface quality is of crucial importance. In order to improve it, appropriate post-processing steps are necessary (e.g. robot polishing or coating), which will be discussed. An essential part of this paper deals with various additive manufactured optical components and their use, especially in optical systems for shape metrology (e.g. borehole sensor, tilt sensor, freeform surface sensor, fisheye lens). The examples should demonstrate the potentials and limitations of optical components produced by additive manufacturing.

The design of red-blue 3D video fusion system based on DM642

NASA Astrophysics Data System (ADS)

Fu, Rongguo; Luo, Hao; Lv, Jin; Feng, Shu; Wei, Yifang; Zhang, Hao

2016-10-01

Aiming at the uncertainty of traditional 3D video capturing including camera focal lengths, distance and angle parameters between two cameras, a red-blue 3D video fusion system based on DM642 hardware processing platform is designed with the parallel optical axis. In view of the brightness reduction of traditional 3D video, the brightness enhancement algorithm based on human visual characteristics is proposed and the luminance component processing method based on YCbCr color space is also proposed. The BIOS real-time operating system is used to improve the real-time performance. The video processing circuit with the core of DM642 enhances the brightness of the images, then converts the video signals of YCbCr to RGB and extracts the R component from one camera, so does the other video and G, B component are extracted synchronously, outputs 3D fusion images finally. The real-time adjustments such as translation and scaling of the two color components are realized through the serial communication between the VC software and BIOS. The system with the method of adding red-blue components reduces the lost of the chrominance components and makes the picture color saturation reduce to more than 95% of the original. Enhancement algorithm after optimization to reduce the amount of data fusion in the processing of video is used to reduce the fusion time and watching effect is improved. Experimental results show that the system can capture images in near distance, output red-blue 3D video and presents the nice experiences to the audience wearing red-blue glasses.

Principles of Quantum Mechanics

NASA Astrophysics Data System (ADS)

Landé, Alfred

2013-10-01

Preface; Introduction: 1. Observation and interpretation; 2. Difficulties of the classical theories; 3. The purpose of quantum theory; Part I. Elementary Theory of Observation (Principle of Complementarity): 4. Refraction in inhomogeneous media (force fields); 5. Scattering of charged rays; 6. Refraction and reflection at a plane; 7. Absolute values of momentum and wave length; 8. Double ray of matter diffracting light waves; 9. Double ray of matter diffracting photons; 10. Microscopic observation of ρ (x) and σ (p); 11. Complementarity; 12. Mathematical relation between ρ (x) and σ (p) for free particles; 13. General relation between ρ (q) and σ (p); 14. Crystals; 15. Transition density and transition probability; 16. Resultant values of physical functions; matrix elements; 17. Pulsating density; 18. General relation between ρ (t) and σ (є); 19. Transition density; matrix elements; Part II. The Principle of Uncertainty: 20. Optical observation of density in matter packets; 21. Distribution of momenta in matter packets; 22. Mathematical relation between ρ and σ; 23. Causality; 24. Uncertainty; 25. Uncertainty due to optical observation; 26. Dissipation of matter packets; rays in Wilson Chamber; 27. Density maximum in time; 28. Uncertainty of energy and time; 29. Compton effect; 30. Bothe-Geiger and Compton-Simon experiments; 31. Doppler effect; Raman effect; 32. Elementary bundles of rays; 33. Jeans' number of degrees of freedom; 34. Uncertainty of electromagnetic field components; Part III. The Principle of Interference and Schrödinger's equation: 35. Physical functions; 36. Interference of probabilities for p and q; 37. General interference of probabilities; 38. Differential equations for Ψp (q) and Xq (p); 39. Differential equation for фβ (q); 40. The general probability amplitude Φβ' (Q); 41. Point transformations; 42. General theorem of interference; 43. Conjugate variables; 44. Schrödinger's equation for conservative systems; 45. Schrödinger's equation for non-conservative systems; 46. Pertubation theory; 47. Orthogonality, normalization and Hermitian conjugacy; 48. General matrix elements; Part IV. The Principle of Correspondence: 49. Contact transformations in classical mechanics; 50. Point transformations; 51. Contact transformations in quantum mechanics; 52. Constants of motion and angular co-ordinates; 53. Periodic orbits; 54. De Broglie and Schrödinger function; correspondence to classical mechanics; 55. Packets of probability; 56. Correspondence to hydrodynamics; 57. Motion and scattering of wave packets; 58. Formal correspondence between classical and quantum mechanics; Part V. Mathematical Appendix: Principle of Invariance: 59. The general theorem of transformation; 60. Operator calculus; 61. Exchange relations; three criteria for conjugacy; 62. First method of canonical transformation; 63. Second method of canonical transformation; 64. Proof of the transformation theorem; 65. Invariance of the matrix elements against unitary transformations; 66. Matrix mechanics; Index of literature; Index of names and subjects.

Mid-Infrared Photoacoustic Detection of Glucose in Human Skin: Towards Non-Invasive Diagnostics

PubMed Central

Kottmann, Jonas; Rey, Julien M.; Sigrist, Markus W.

2016-01-01

Diabetes mellitus is a widespread metabolic disease without cure. Great efforts are being made to develop a non-invasive monitoring of the blood glucose level. Various attempts have been made, including a number of non-optical approaches as well as optical techniques involving visible, near- and mid-infrared light. However, no true breakthrough has been achieved so far, i.e., there is no fully non-invasive monitoring device available. Here we present a new study based on mid-infrared spectroscopy and photoacoustic detection. We employ two setups, one with a fiber-coupled photoacoustic (PA) cell and a tunable quantum cascade laser (QCL), and a second setup with two QCLs at different wavelengths combined with PA detection. In both cases, the PA cells are in direct skin contact. The performance is tested with an oral glucose tolerance test. While the first setup often gives reasonable qualitative agreement with ordinary invasive blood glucose measurements, the dual-wavelength approach yields a considerably improved stability and an uncertainty of only ±30 mg/dL of the blood glucose concentration level at a confidence level of 90%. This result is achieved without advanced data treatment such as principal component analysis involving extended wavelength ranges. PMID:27735878

THE IDENTIFICATION OF THE X-RAY COUNTERPART TO PSR J2021+4026

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weisskopf, Martin C.; Elsner, Ronald F.; O'Dell, Stephen L.

2011-12-10

We report the probable identification of the X-ray counterpart to the {gamma}-ray pulsar PSR J2021+4026 using imaging with the Chandra X-ray Observatory Advanced CCD Imaging Spectrometer and timing analysis with the Fermi satellite. Given the statistical and systematic errors, the positions determined by both satellites are coincident. The X-ray source position is R.A. 20{sup h}21{sup m}30.{sup s}733, decl. +40 Degree-Sign 26'46.''04 (J2000) with an estimated uncertainty of 1.''3 combined statistical and systematic error. Moreover, both the X-ray to {gamma}-ray and the X-ray to optical flux ratios are sensible assuming a neutron star origin for the X-ray flux. The X-ray sourcemore » has no cataloged infrared-to-visible counterpart and, through new observations, we set upper limits to its optical emission of i' > 23.0 mag and r' > 25.2 mag. The source exhibits an X-ray spectrum with most likely both a power law and a thermal component. We also report on the X-ray and visible light properties of the 43 other sources detected in our Chandra observation.« less

The Identification Of The X-Ray Counterpart To PSR J2021+4026

DOE PAGES

Weisskopf, Martin C.; Romani, Roger W.; Razzano, Massimiliano; ...

2011-11-23

We report the probable identification of the X-ray counterpart to the γ-ray pulsar PSR J2021+4026 using imaging with the Chandra X-ray Observatory ACIS and timing analysis with the Fermi satellite. Given the statistical and systematic errors, the positions determined by both satellites are coincident. The X-ray source position is R.A. 20h21m30s.733, Decl. +40°26'46.04" (J2000) with an estimated uncertainty of 1."3 combined statistical and systematic error. Moreover, both the X-ray to γ-ray and the X-ray to optical flux ratios are sensible assuming a neutron star origin for the X-ray flux. The X-ray source has no cataloged infrared-to-visible counterpart and, through newmore » observations, we set upper limits to its optical emission of i' > 23.0 mag and r' > 25.2 mag. The source exhibits an X-ray spectrum with most likely both a powerlaw and a thermal component. We also report on the X-ray and visible light properties of the 43 other sources detected in our Chandra observation.« less

Decomposing Trends in Inequality in Earnings into Forecastable and Uncertain Components

PubMed Central

Cunha, Flavio; Heckman, James

2015-01-01

A substantial empirical literature documents the rise in wage inequality in the American economy. It is silent on whether the increase in inequality is due to components of earnings that are predictable by agents or whether it is due to greater uncertainty facing them. These two sources of variability have different consequences for both aggregate and individual welfare. Using data on two cohorts of American males we find that a large component of the rise in inequality for less skilled workers is due to uncertainty. For skilled workers, the rise is less pronounced. PMID:27087741

Improved evaluation of optical depth components from Langley plot data

NASA Technical Reports Server (NTRS)

Biggar, S. F.; Gellman, D. I.; Slater, P. N.

1990-01-01

A simple, iterative procedure to determine the optical depth components of the extinction optical depth measured by a solar radiometer is presented. Simulated data show that the iterative procedure improves the determination of the exponent of a Junge law particle size distribution. The determination of the optical depth due to aerosol scattering is improved as compared to a method which uses only two points from the extinction data. The iterative method was used to determine spectral optical depth components for June 11-13, 1988 during the MAC III experiment.

Determination of reference values for optical properties of liquid phantoms based on Intralipid and India ink

PubMed Central

Spinelli, L.; Botwicz, M.; Zolek, N.; Kacprzak, M.; Milej, D.; Sawosz, P.; Liebert, A.; Weigel, U.; Durduran, T.; Foschum, F.; Kienle, A.; Baribeau, F.; Leclair, S.; Bouchard, J.-P.; Noiseux, I.; Gallant, P.; Mermut, O.; Farina, A.; Pifferi, A.; Torricelli, A.; Cubeddu, R.; Ho, H.-C.; Mazurenka, M.; Wabnitz, H.; Klauenberg, K.; Bodnar, O.; Elster, C.; Bénazech-Lavoué, M.; Bérubé-Lauzière, Y.; Lesage, F.; Khoptyar, D.; Subash, A. A.; Andersson-Engels, S.; Di Ninni, P.; Martelli, F.; Zaccanti, G.

2014-01-01

A multi-center study has been set up to accurately characterize the optical properties of diffusive liquid phantoms based on Intralipid and India ink at near-infrared (NIR) wavelengths. Nine research laboratories from six countries adopting different measurement techniques, instrumental set-ups, and data analysis methods determined at their best the optical properties and relative uncertainties of diffusive dilutions prepared with common samples of the two compounds. By exploiting a suitable statistical model, comprehensive reference values at three NIR wavelengths for the intrinsic absorption coefficient of India ink and the intrinsic reduced scattering coefficient of Intralipid-20% were determined with an uncertainty of about 2% or better, depending on the wavelength considered, and 1%, respectively. Even if in this study we focused on particular batches of India ink and Intralipid, the reference values determined here represent a solid and useful starting point for preparing diffusive liquid phantoms with accurately defined optical properties. Furthermore, due to the ready availability, low cost, long-term stability and batch-to-batch reproducibility of these compounds, they provide a unique fundamental tool for the calibration and performance assessment of diffuse optical spectroscopy instrumentation intended to be used in laboratory or clinical environment. Finally, the collaborative work presented here demonstrates that the accuracy level attained in this work for optical properties of diffusive phantoms is reliable. PMID:25071947

Integrated optics technology study

NASA Technical Reports Server (NTRS)

Chen, B.; Findakly, T.; Innarella, R.

1982-01-01

The status and near term potential of materials and processes available for the fabrication of single mode integrated electro-optical components are discussed. Issues discussed are host material and orientation, waveguide formation, optical loss mechanisms, wavelength selection, polarization effects and control, laser to integrated optics coupling fiber optic waveguides to integrated optics coupling, sources, and detectors. Recommendations of the best materials, technology, and processes for fabrication of integrated optical components for communications and fiber gyro applications are given.

WE-E-18A-04: Precision In-Vivo Dosimetry Using Optically Stimulated Luminescence Dosimeters and a Pulsed-Stimulating Dose Reader

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Q; Herrick, A; Hoke, S

Purpose: A new readout technology based on pulsed optically stimulating luminescence is introduced (microSTARii, Landauer, Inc, Glenwood, IL60425). This investigation searches for approaches that maximizes the dosimetry accuracy in clinical applications. Methods: The sensitivity of each optically stimulated luminescence dosimeter (OSLD) was initially characterized by exposing it to a given radiation beam. After readout, the luminescence signal stored in the OSLD was erased by exposing its sensing area to a 21W white LED light for 24 hours. A set of OSLDs with consistent sensitivities was selected to calibrate the dose reader. Higher order nonlinear curves were also derived from themore » calibration readings. OSLDs with cumulative doses below 15 Gy were reused. Before an in-vivo dosimetry, the OSLD luminescence signal was erased with the white LED light. Results: For a set of 68 manufacturer-screened OSLDs, the measured sensitivities vary in a range of 17.3%. A sub-set of the OSLDs with sensitivities within ±1% was selected for the reader calibration. Three OSLDs in a group were exposed to a given radiation. Nine groups were exposed to radiation doses ranging from 0 to 13 Gy. Additional verifications demonstrated that the reader uncertainty is about 3%. With an external calibration function derived by fitting the OSLD readings to a 3rd-order polynomial, the dosimetry uncertainty dropped to 0.5%. The dose-luminescence response curves of individual OSLDs were characterized. All curves converge within 1% after the sensitivity correction. With all uncertainties considered, the systematic uncertainty is about 2%. Additional tests emulating in-vivo dosimetry by exposing the OSLDs under different radiation sources confirmed the claim. Conclusion: The sensitivity of individual OSLD should be characterized initially. A 3rd-order polynomial function is a more accurate representation of the dose-luminescence response curve. The dosimetry uncertainty specified by the manufacturer is 4%. Following the proposed approach, it can be controlled to 2%.« less

Predicting the Earth encounters of (99942) Apophis

NASA Technical Reports Server (NTRS)

Giorgini, Jon D.; Benner, Lance A. M.; Ostro, Steven J.; Nolan, Michael C.; Busch, Michael W.

2007-01-01

Arecibo delay-Doppler measurements of (99942) Apophis in 2005 and 2006 resulted in a five standard-deviation trajectory correction to the optically predicted close approach distance to Earth in 2029. The radar measurements reduced the volume of the statistical uncertainty region entering the encounter to 7.3% of the pre-radar solution, but increased the trajectory uncertainty growth rate across the encounter by 800% due to the closer predicted approach to the Earth. A small estimated Earth impact probability remained for 2036. With standard-deviation plane-of-sky position uncertainties for 2007-2010 already less than 0.2 arcsec, the best near-term ground-based optical astrometry can only weakly affect the trajectory estimate. While the potential for impact in 2036 will likely be excluded in 2013 (if not 2011) using ground-based optical measurements, approximations within the Standard Dynamical Model (SDM) used to estimate and predict the trajectory from the current era are sufficient to obscure the difference between a predicted impact and a miss in 2036 by altering the dynamics leading into the 2029 encounter. Normal impact probability assessments based on the SDM become problematic without knowledge of the object's physical properties; impact could be excluded while the actual dynamics still permit it. Calibrated position uncertainty intervals are developed to compensate for this by characterizing the minimum and maximum effect of physical parameters on the trajectory. Uncertainty in accelerations related to solar radiation can cause between 82 and 4720 Earth-radii of trajectory change relative to the SDM by 2036. If an actionable hazard exists, alteration by 2-10% of Apophis' total absorption of solar radiation in 2018 could be sufficient to produce a six standard-deviation trajectory change by 2036 given physical characterization; even a 0.5% change could produce a trajectory shift of one Earth-radius by 2036 for all possible spin-poles and likely masses. Planetary ephemeris uncertainties are the next greatest source of systematic error, causing up to 23 Earth-radii of uncertainty. The SDM Earth point-mass assumption introduces an additional 2.9 Earth-radii of prediction error by 2036. Unmodeled asteroid perturbations produce as much as 2.3 Earth-radii of error. We find no future small-body encounters likely to yield an Apophis mass determination prior to 2029. However, asteroid (144898) 2004 VD17, itself having a statistical Earth impact in 2102, will probably encounter Apophis at 6.7 lunar distances in 2034, their uncertainty regions coming as close as 1.6 lunar distances near the center of both SDM probability distributions.

All-optical nanoscale thermometry with silicon-vacancy centers in diamond

NASA Astrophysics Data System (ADS)

Nguyen, Christian T.; Evans, Ruffin E.; Sipahigil, Alp; Bhaskar, Mihir K.; Sukachev, Denis D.; Agafonov, Viatcheslav N.; Davydov, Valery A.; Kulikova, Liudmila F.; Jelezko, Fedor; Lukin, Mikhail D.

2018-05-01

We demonstrate an all-optical thermometer based on an ensemble of silicon-vacancy centers (SiVs) in diamond by utilizing the sensitivity of the zero-phonon line wavelength to temperature, Δλ/ΔT =0.0124 (2 ) nm K-1 [6.8(1) GHz K-1]. Using SiVs in bulk diamond, we achieve 70 mK precision at room temperature with a temperature uncertainty σT=360 mK/√{H z } . Finally, we use SiVs in 200 nm nanodiamonds as local temperature probes with 521 mK/ √{H z } uncertainty and achieve sub-Kelvin precision. These properties deviate by less than 1% between nanodiamonds, enabling calibration-free thermometry for sensing and control of complex nanoscale systems.

Uncertainty assessment method for the Cs-137 fallout inventory and penetration depth.

PubMed

Papadakos, G N; Karangelos, D J; Petropoulos, N P; Anagnostakis, M J; Hinis, E P; Simopoulos, S E

2017-05-01

Within the presented study, soil samples were collected in year 2007 at 20 different locations of the Greek terrain, both from the surface and also from depths down to 26 cm. Sampling locations were selected primarily from areas where high levels of 137 Cs deposition after the Chernobyl accident had already been identified by the Nuclear Engineering Laboratory of the National Technical University of Athens during and after the year of 1986. At one location of relatively higher deposition, soil core samples were collected following a 60 m by 60 m Cartesian grid with a 20 m node-to-node distance. Single or pair core samples were also collected from the remaining 19 locations. Sample measurements and analysis were used to estimate 137 Cs inventory and the corresponding depth migration, twenty years after the deposition on Greek terrain. Based on these data, the uncertainty components of the whole sampling-to-results procedure were investigated. A cause-and-effect assessment process was used to apply the law of error propagation and demonstrate that the dominating significant component of the combined uncertainty is that due to the spatial variability of the contemporary (2007) 137 Cs inventory. A secondary, yet also significant component was identified to be the activity measurement process itself. Other less-significant uncertainty parameters were sampling methods, the variation in the soil field density with depth and the preparation of samples for measurement. The sampling grid experiment allowed for the quantitative evaluation of the uncertainty due to spatial variability, also by the assistance of the semivariance analysis. Denser, optimized grid could return more accurate values for this component but with a significantly elevated laboratory cost, in terms of both, human and material resources. Using the hereby collected data and for the case of a single core soil sampling using a well-defined sampling methodology quality assurance, the uncertainty component due to spatial variability was evaluated to about 19% for the 137 Cs inventory and up to 34% for the 137 Cs penetration depth. Based on the presented results and also on related literature, it is argued that such high uncertainties should be anticipated for single core samplings conducted using similar methodology and employed as 137 Cs inventory and penetration depth estimators. Copyright © 2017 Elsevier Ltd. All rights reserved.

Assessment of Uncertainties for the NIST 1016 mm Guarded-Hot-Plate Apparatus: Extended Analysis for Low-Density Fibrous-Glass Thermal Insulation.

PubMed

Zarr, Robert R

2010-01-01

An assessment of uncertainties for the National Institute of Standards and Technology (NIST) 1016 mm Guarded-Hot-Plate apparatus is presented. The uncertainties are reported in a format consistent with current NIST policy on the expression of measurement uncertainty. The report describes a procedure for determination of component uncertainties for thermal conductivity and thermal resistance for the apparatus under operation in either the double-sided or single-sided mode of operation. An extensive example for computation of uncertainties for the single-sided mode of operation is provided for a low-density fibrous-glass blanket thermal insulation. For this material, the relative expanded uncertainty for thermal resistance increases from 1 % for a thickness of 25.4 mm to 3 % for a thickness of 228.6 mm. Although these uncertainties have been developed for a particular insulation material, the procedure and, to a lesser extent, the results are applicable to other insulation materials measured at a mean temperature close to 297 K (23.9 °C, 75 °F). The analysis identifies dominant components of uncertainty and, thus, potential areas for future improvement in the measurement process. For the NIST 1016 mm Guarded-Hot-Plate apparatus, considerable improvement, especially at higher values of thermal resistance, may be realized by developing better control strategies for guarding that include better measurement techniques for the guard gap thermopile voltage and the temperature sensors.

Assessment of Uncertainties for the NIST 1016 mm Guarded-Hot-Plate Apparatus: Extended Analysis for Low-Density Fibrous-Glass Thermal Insulation

PubMed Central

Zarr, Robert R.

2010-01-01

An assessment of uncertainties for the National Institute of Standards and Technology (NIST) 1016 mm Guarded-Hot-Plate apparatus is presented. The uncertainties are reported in a format consistent with current NIST policy on the expression of measurement uncertainty. The report describes a procedure for determination of component uncertainties for thermal conductivity and thermal resistance for the apparatus under operation in either the double-sided or single-sided mode of operation. An extensive example for computation of uncertainties for the single-sided mode of operation is provided for a low-density fibrous-glass blanket thermal insulation. For this material, the relative expanded uncertainty for thermal resistance increases from 1 % for a thickness of 25.4 mm to 3 % for a thickness of 228.6 mm. Although these uncertainties have been developed for a particular insulation material, the procedure and, to a lesser extent, the results are applicable to other insulation materials measured at a mean temperature close to 297 K (23.9 °C, 75 °F). The analysis identifies dominant components of uncertainty and, thus, potential areas for future improvement in the measurement process. For the NIST 1016 mm Guarded-Hot-Plate apparatus, considerable improvement, especially at higher values of thermal resistance, may be realized by developing better control strategies for guarding that include better measurement techniques for the guard gap thermopile voltage and the temperature sensors. PMID:27134779

Routine internal- and external-quality control data in clinical laboratories for estimating measurement and diagnostic uncertainty using GUM principles.

PubMed

Magnusson, Bertil; Ossowicki, Haakan; Rienitz, Olaf; Theodorsson, Elvar

2012-05-01

Healthcare laboratories are increasingly joining into larger laboratory organizations encompassing several physical laboratories. This caters for important new opportunities for re-defining the concept of a 'laboratory' to encompass all laboratories and measurement methods measuring the same measurand for a population of patients. In order to make measurement results, comparable bias should be minimized or eliminated and measurement uncertainty properly evaluated for all methods used for a particular patient population. The measurement as well as diagnostic uncertainty can be evaluated from internal and external quality control results using GUM principles. In this paper the uncertainty evaluations are described in detail using only two main components, within-laboratory reproducibility and uncertainty of the bias component according to a Nordtest guideline. The evaluation is exemplified for the determination of creatinine in serum for a conglomerate of laboratories both expressed in absolute units (μmol/L) and relative (%). An expanded measurement uncertainty of 12 μmol/L associated with concentrations of creatinine below 120 μmol/L and of 10% associated with concentrations above 120 μmol/L was estimated. The diagnostic uncertainty encompasses both measurement uncertainty and biological variation, and can be estimated for a single value and for a difference. This diagnostic uncertainty for the difference for two samples from the same patient was determined to be 14 μmol/L associated with concentrations of creatinine below 100 μmol/L and 14 % associated with concentrations above 100 μmol/L.

Impact of Measurement Uncertainties on Receptor Modeling of Speciated Atmospheric Mercury.

PubMed

Cheng, I; Zhang, L; Xu, X

2016-02-09

Gaseous oxidized mercury (GOM) and particle-bound mercury (PBM) measurement uncertainties could potentially affect the analysis and modeling of atmospheric mercury. This study investigated the impact of GOM measurement uncertainties on Principal Components Analysis (PCA), Absolute Principal Component Scores (APCS), and Concentration-Weighted Trajectory (CWT) receptor modeling results. The atmospheric mercury data input into these receptor models were modified by combining GOM and PBM into a single reactive mercury (RM) parameter and excluding low GOM measurements to improve the data quality. PCA and APCS results derived from RM or excluding low GOM measurements were similar to those in previous studies, except for a non-unique component and an additional component extracted from the RM dataset. The percent variance explained by the major components from a previous study differed slightly compared to RM and excluding low GOM measurements. CWT results were more sensitive to the input of RM than GOM excluding low measurements. Larger discrepancies were found between RM and GOM source regions than those between RM and PBM. Depending on the season, CWT source regions of RM differed by 40-61% compared to GOM from a previous study. No improvement in correlations between CWT results and anthropogenic mercury emissions were found.

Impact of Measurement Uncertainties on Receptor Modeling of Speciated Atmospheric Mercury

PubMed Central

Cheng, I.; Zhang, L.; Xu, X.

2016-01-01

Gaseous oxidized mercury (GOM) and particle-bound mercury (PBM) measurement uncertainties could potentially affect the analysis and modeling of atmospheric mercury. This study investigated the impact of GOM measurement uncertainties on Principal Components Analysis (PCA), Absolute Principal Component Scores (APCS), and Concentration-Weighted Trajectory (CWT) receptor modeling results. The atmospheric mercury data input into these receptor models were modified by combining GOM and PBM into a single reactive mercury (RM) parameter and excluding low GOM measurements to improve the data quality. PCA and APCS results derived from RM or excluding low GOM measurements were similar to those in previous studies, except for a non-unique component and an additional component extracted from the RM dataset. The percent variance explained by the major components from a previous study differed slightly compared to RM and excluding low GOM measurements. CWT results were more sensitive to the input of RM than GOM excluding low measurements. Larger discrepancies were found between RM and GOM source regions than those between RM and PBM. Depending on the season, CWT source regions of RM differed by 40–61% compared to GOM from a previous study. No improvement in correlations between CWT results and anthropogenic mercury emissions were found. PMID:26857835

Sixth International Conference on Squeezed States and Uncertainty Relations

NASA Technical Reports Server (NTRS)

Han, D. (Editor); Kim, Y. S. (Editor); Solimento, S. (Editor)

2000-01-01

These proceedings contain contributions from about 200 participants to the 6th International Conference on Squeezed States and Uncertainty Relations (ICSSUR'99) held in Naples May 24-29, 1999, and organized jointly by the University of Naples "Federico II," the University of Maryland at College Park, and the Lebedev Institute, Moscow. This was the sixth of a series of very successful meetings started in 1990 at the College Park Campus of the University of Maryland. The other meetings in the series were held in Moscow (1992), Baltimore (1993), Taiyuan P.R.C. (1995) and Balatonfuered, Hungary (1997). The present one was held at the campus Monte Sant'Angelo of the University "Federico II" of Naples. The meeting sought to provide a forum for updating and reviewing a wide range of quantum optics disciplines, including device developments and applications, and related areas of quantum measurements and quantum noise. Over the years, the ICSSUR Conference evolved from a meeting on quantum measurement sector of quantum optics, to a wide range of quantum optics themes, including multifacet aspects of generation, measurement, and applications of nonclassical light (squeezed and Schrodinger cat radiation fields, etc.), and encompassing several related areas, ranging from quantum measurement to quantum noise. ICSSUR'99 brought together about 250 people active in the field of quantum optics, with special emphasis on nonclassical light sources and related areas. The Conference was organized in 8 Sections: Squeezed states and uncertainty relations; Harmonic oscillators and squeeze transformations; Methods of quantum interference and correlations; Quantum measurements; Generation and characterisation of non-classical light; Quantum noise; Quantum communication and information; and Quantum-like systems.

Constraints on the optical depth of galaxy groups and clusters

DOE PAGES

Flender, Samuel; Nagai, Daisuke; McDonald, Michael

2017-03-10

Here, future data from galaxy redshift surveys, combined with high-resolutions maps of the cosmic microwave background, will enable measurements of the pairwise kinematic Sunyaev–Zel'dovich (kSZ) signal with unprecedented statistical significance. This signal probes the matter-velocity correlation function, scaled by the average optical depth (τ) of the galaxy groups and clusters in the sample, and is thus of fundamental importance for cosmology. However, in order to translate pairwise kSZ measurements into cosmological constraints, external constraints on τ are necessary. In this work, we present a new model for the intracluster medium, which takes into account star formation, feedback, non-thermal pressure, and gas cooling. Our semi-analytic model is computationally efficient and can reproduce results of recent hydrodynamical simulations of galaxy cluster formation. We calibrate the free parameters in the model using recent X-ray measurements of gas density profiles of clusters, and gas masses of groups and clusters. Our observationally calibrated model predicts the averagemore » $${\\tau }_{500}$$ (i.e., the integrated τ within a disk of size R 500) to better than 6% modeling uncertainty (at 95% confidence level). If the remaining uncertainties associated with other astrophysical uncertainties and X-ray selection effects can be better understood, our model for the optical depth should break the degeneracy between optical depth and cluster velocity in the analysis of future pairwise kSZ measurements and improve cosmological constraints with the combination of upcoming galaxy and CMB surveys, including the nature of dark energy, modified gravity, and neutrino mass.« less

Constraints on the optical depth of galaxy groups and clusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flender, Samuel; Nagai, Daisuke; McDonald, Michael

Here, future data from galaxy redshift surveys, combined with high-resolutions maps of the cosmic microwave background, will enable measurements of the pairwise kinematic Sunyaev–Zel'dovich (kSZ) signal with unprecedented statistical significance. This signal probes the matter-velocity correlation function, scaled by the average optical depth (τ) of the galaxy groups and clusters in the sample, and is thus of fundamental importance for cosmology. However, in order to translate pairwise kSZ measurements into cosmological constraints, external constraints on τ are necessary. In this work, we present a new model for the intracluster medium, which takes into account star formation, feedback, non-thermal pressure, and gas cooling. Our semi-analytic model is computationally efficient and can reproduce results of recent hydrodynamical simulations of galaxy cluster formation. We calibrate the free parameters in the model using recent X-ray measurements of gas density profiles of clusters, and gas masses of groups and clusters. Our observationally calibrated model predicts the averagemore » $${\\tau }_{500}$$ (i.e., the integrated τ within a disk of size R 500) to better than 6% modeling uncertainty (at 95% confidence level). If the remaining uncertainties associated with other astrophysical uncertainties and X-ray selection effects can be better understood, our model for the optical depth should break the degeneracy between optical depth and cluster velocity in the analysis of future pairwise kSZ measurements and improve cosmological constraints with the combination of upcoming galaxy and CMB surveys, including the nature of dark energy, modified gravity, and neutrino mass.« less

Development and Validation of a Lifecycle-based Prognostics Architecture with Test Bed Validation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hines, J. Wesley; Upadhyaya, Belle; Sharp, Michael

On-line monitoring and tracking of nuclear plant system and component degradation is being investigated as a method for improving the safety, reliability, and maintainability of aging nuclear power plants. Accurate prediction of the current degradation state of system components and structures is important for accurate estimates of their remaining useful life (RUL). The correct quantification and propagation of both the measurement uncertainty and model uncertainty is necessary for quantifying the uncertainty of the RUL prediction. This research project developed and validated methods to perform RUL estimation throughout the lifecycle of plant components. Prognostic methods should seamlessly operate from beginning ofmore » component life (BOL) to end of component life (EOL). We term this "Lifecycle Prognostics." When a component is put into use, the only information available may be past failure times of similar components used in similar conditions, and the predicted failure distribution can be estimated with reliability methods such as Weibull Analysis (Type I Prognostics). As the component operates, it begins to degrade and consume its available life. This life consumption may be a function of system stresses, and the failure distribution should be updated to account for the system operational stress levels (Type II Prognostics). When degradation becomes apparent, this information can be used to again improve the RUL estimate (Type III Prognostics). This research focused on developing prognostics algorithms for the three types of prognostics, developing uncertainty quantification methods for each of the algorithms, and, most importantly, developing a framework using Bayesian methods to transition between prognostic model types and update failure distribution estimates as new information becomes available. The developed methods were then validated on a range of accelerated degradation test beds. The ultimate goal of prognostics is to provide an accurate assessment for RUL predictions, with as little uncertainty as possible. From a reliability and maintenance standpoint, there would be improved safety by avoiding all failures. Calculated risk would decrease, saving money by avoiding unnecessary maintenance. One major bottleneck for data-driven prognostics is the availability of run-to-failure degradation data. Without enough degradation data leading to failure, prognostic models can yield RUL distributions with large uncertainty or mathematically unsound predictions. To address these issues a "Lifecycle Prognostics" method was developed to create RUL distributions from Beginning of Life (BOL) to End of Life (EOL). This employs established Type I, II, and III prognostic methods, and Bayesian transitioning between each Type. Bayesian methods, as opposed to classical frequency statistics, show how an expected value, a priori, changes with new data to form a posterior distribution. For example, when you purchase a component you have a prior belief, or estimation, of how long it will operate before failing. As you operate it, you may collect information related to its condition that will allow you to update your estimated failure time. Bayesian methods are best used when limited data are available. The use of a prior also means that information is conserved when new data are available. The weightings of the prior belief and information contained in the sampled data are dependent on the variance (uncertainty) of the prior, the variance (uncertainty) of the data, and the amount of measured data (number of samples). If the variance of the prior is small compared to the uncertainty of the data, the prior will be weighed more heavily. However, as more data are collected, the data will be weighted more heavily and will eventually swamp out the prior in calculating the posterior distribution of model parameters. Fundamentally Bayesian analysis updates a prior belief with new data to get a posterior belief. The general approach to applying the Bayesian method to lifecycle prognostics consisted of identifying the prior, which is the RUL estimate and uncertainty from the previous prognostics type, and combining it with observational data related to the newer prognostics type. The resulting lifecycle prognostics algorithm uses all available information throughout the component lifecycle.« less

Seasonal Bias of Retrieved Ice Cloud Optical Properties Based on MISR and MODIS Measurements

NASA Astrophysics Data System (ADS)

Wang, Y.; Hioki, S.; Yang, P.; Di Girolamo, L.; Fu, D.

2017-12-01

The precise estimation of two important cloud optical and microphysical properties, cloud particle optical thickness and cloud particle effective radius, is fundamental in the study of radiative energy budget and hydrological cycle. In retrieving these two properties, an appropriate selection of ice particle surface roughness is important because it substantially affects the single-scattering properties. At present, using a predetermined ice particle shape without spatial and temporal variations is a common practice in satellite-based retrieval. This approach leads to substantial uncertainties in retrievals. The cloud radiances measured by each of the cameras of the Multi-angle Imaging SpectroRadiometer (MISR) instrument are used to estimate spherical albedo values at different scattering angles. By analyzing the directional distribution of estimated spherical albedo values, the degree of ice particle surface roughness is estimated. With an optimal degree of ice particle roughness, cloud optical thickness and effective radius are retrieved based on a bi-spectral shortwave technique in conjunction with two Moderate Resolution Imaging Spectroradiometer (MODIS) bands centered at 0.86 and 2.13 μm. The seasonal biases of retrieved cloud optical and microphysical properties, caused by the uncertainties in ice particle roughness, are investigated by using one year of MISR-MODIS fused data.

Precision measurement of the nuclear polarization in laser-cooled, optically pumped 37 K

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fenker, B.; Behr, J. A.; Melconian, D.

We report a measurement of the nuclear polarization of laser-cooled, optically pumped 37K atoms which will allow us to precisely measure angular correlation parameters in themore » $${\\beta }^{+}$$-decay of the same atoms. These results will be used to test the V ₋ A framework of the weak interaction at high precision. At the Triumf neutral atom trap (Trinat), a magneto-optical trap confines and cools neutral 37K atoms and optical pumping spin-polarizes them. We monitor the nuclear polarization of the same atoms that are decaying in situ by photoionizing a small fraction of the partially polarized atoms and then use the standard optical Bloch equations to model their population distribution. We obtain an average nuclear polarization of $$\\bar{P}=0.9913\\pm 0.0009$$, which is significantly more precise than previous measurements with this technique. Since our current measurement of the β-asymmetry has $$0.2 \\% $$ statistical uncertainty, the polarization measurement reported here will not limit its overall uncertainty. This result also demonstrates the capability to measure the polarization to $$\\lt 0.1 \\% $$, allowing for a measurement of angular correlation parameters to this level of precision, which would be competitive in searches for new physics.« less

Precision measurement of the nuclear polarization in laser-cooled, optically pumped 37 K

DOE PAGES

Fenker, B.; Behr, J. A.; Melconian, D.; ...

2016-07-13

We report a measurement of the nuclear polarization of laser-cooled, optically pumped 37K atoms which will allow us to precisely measure angular correlation parameters in themore » $${\\beta }^{+}$$-decay of the same atoms. These results will be used to test the V ₋ A framework of the weak interaction at high precision. At the Triumf neutral atom trap (Trinat), a magneto-optical trap confines and cools neutral 37K atoms and optical pumping spin-polarizes them. We monitor the nuclear polarization of the same atoms that are decaying in situ by photoionizing a small fraction of the partially polarized atoms and then use the standard optical Bloch equations to model their population distribution. We obtain an average nuclear polarization of $$\\bar{P}=0.9913\\pm 0.0009$$, which is significantly more precise than previous measurements with this technique. Since our current measurement of the β-asymmetry has $$0.2 \\% $$ statistical uncertainty, the polarization measurement reported here will not limit its overall uncertainty. This result also demonstrates the capability to measure the polarization to $$\\lt 0.1 \\% $$, allowing for a measurement of angular correlation parameters to this level of precision, which would be competitive in searches for new physics.« less

Scattering and Absorption Properties of Biomaterials for Dental Restorative Applications

NASA Astrophysics Data System (ADS)

Fernandez-Oliveras, A.; Rubiño, M.; Pérez, M. M.

2013-08-01

The physical understanding of the optical properties of dental biomaterials is mandatory for their final success in restorative applications.Light propagation in biological media is characterized by the absorption coefficient, the scattering coefficient, the scattering phase function,the refractive index, and the surface conditions (roughness). We have employed the inverse adding-doubling (IAD) method to combine transmittance and reflectance measurements performed using an integrating-sphere setup with the results of the previous scattering-anisotropygoniometric measurements. This has led to the determination of the absorption and the scattering coefficients. The aim was to optically characterize two different dental-resin composites (nanocomposite and hybrid) and one type of zirconia ceramic, and comparatively study them. The experimental procedure was conducted under repeatability conditions of measurement in order to determine the uncertainty associated to the optical properties of the biomaterials. Spectral variations of the refraction index and the scattering anisotropy factor were also considered. The whole experimental procedure fulfilled all the necessary requirements to provide optical-property values with lower associated uncertainties. The effective transport coefficient presented a similar spectral behavior for the two composites but completely different for the zirconia ceramic. The results demonstrated that the scattering anisotropy exerted a clearly distinct impact on the optical properties of the zirconia ceramic compared with those of the dental-resin composites.

LDEF active optical system components experiment

NASA Technical Reports Server (NTRS)

Blue, M. D.

1992-01-01

A preliminary report on the Active Optical System Components Experiment is presented. This experiment contained 136 components in a six inch deep tray including lasers, infrared detectors and arrays, ultraviolet light detectors, light-emitting diodes, a light modulator, flash lamps, optical filters, glasses, and samples of surface finishes. Thermal, mechanical, and structural considerations leading to the design of the tray hardware are discussed. In general, changes in the retested component characteristics appear as much related to the passage of time as to the effects of the space environment, but organic materials, multilayer optical interference filters, and extreme-infrared reflectivity of black paints show unexpected changes.

System for generating shaped optical pulses and measuring optical pulses using spectral beam deflection (SBD)

DOEpatents

Skupsky, Stanley; Kessler, Terrance J.; Letzring, Samuel A.

1993-01-01

A temporally shaped or modified optical output pulse is generated from a bandwidth-encoded optical input pulse in a system in which the input pulse is in the form of a beam which is spectrally spread into components contained within the bandwidth, followed by deflection of the spectrally spread beam (SBD) thereby spatially mapping the components in correspondence with the temporal input pulse profile in the focal plane of a lens, and by spatially selective attenuation of selected components in that focal plane. The shaped or modified optical output pulse is then reconstructed from the attenuated spectral components. The pulse-shaping system is particularly useful for generating optical pulses of selected temporal shape over a wide range of pulse duration, such pulses finding application in the fields of optical communication, optical recording and data storage, atomic and molecular spectroscopy and laser fusion. An optical streak camera is also provided which uses SBD to display the beam intensity in the focal plane as a function of time during the input pulse.

System for generating shaped optical pulses and measuring optical pulses using spectral beam deflection (SBD)

DOEpatents

Skupsky, S.; Kessler, T.J.; Letzring, S.A.

1993-11-16

A temporally shaped or modified optical output pulse is generated from a bandwidth-encoded optical input pulse in a system in which the input pulse is in the form of a beam which is spectrally spread into components contained within the bandwidth, followed by deflection of the spectrally spread beam (SBD) thereby spatially mapping the components in correspondence with the temporal input pulse profile in the focal plane of a lens, and by spatially selective attenuation of selected components in that focal plane. The shaped or modified optical output pulse is then reconstructed from the attenuated spectral components. The pulse-shaping system is particularly useful for generating optical pulses of selected temporal shape over a wide range of pulse duration, such pulses finding application in the fields of optical communication, optical recording and data storage, atomic and molecular spectroscopy and laser fusion. An optical streak camera is also provided which uses SBD to display the beam intensity in the focal plane as a function of time during the input pulse. 10 figures.

Strain Gauge Balance Uncertainty Analysis at NASA Langley: A Technical Review

NASA Technical Reports Server (NTRS)

Tripp, John S.

1999-01-01

This paper describes a method to determine the uncertainties of measured forces and moments from multi-component force balances used in wind tunnel tests. A multivariate regression technique is first employed to estimate the uncertainties of the six balance sensitivities and 156 interaction coefficients derived from established balance calibration procedures. These uncertainties are then employed to calculate the uncertainties of force-moment values computed from observed balance output readings obtained during tests. Confidence and prediction intervals are obtained for each computed force and moment as functions of the actual measurands. Techniques are discussed for separate estimation of balance bias and precision uncertainties.

Space shuttle launch vehicle aerodynamic uncertainties: Lessons learned

NASA Technical Reports Server (NTRS)

Hamilton, J. T.

1983-01-01

The chronological development and evolution of an uncertainties model which defines the complex interdependency and interaction of the individual Space Shuttle element and component uncertainties for the launch vehicle are presented. Emphasis is placed on user requirements which dictated certain concessions, simplifications, and assumptions in the analytical model. The use of the uncertainty model in the vehicle design process and flight planning support is discussed. The terminology and justification associated with tolerances as opposed to variations are also presented. Comparisons of and conclusions drawn from flight minus predicted data and uncertainties are given. Lessons learned from the Space Shuttle program concerning aerodynamic uncertainties are examined.

A Discussion on Uncertainty Representation and Interpretation in Model-Based Prognostics Algorithms based on Kalman Filter Estimation Applied to Prognostics of Electronics Components

NASA Technical Reports Server (NTRS)

Celaya, Jose R.; Saxen, Abhinav; Goebel, Kai

2012-01-01

This article discusses several aspects of uncertainty representation and management for model-based prognostics methodologies based on our experience with Kalman Filters when applied to prognostics for electronics components. In particular, it explores the implications of modeling remaining useful life prediction as a stochastic process and how it relates to uncertainty representation, management, and the role of prognostics in decision-making. A distinction between the interpretations of estimated remaining useful life probability density function and the true remaining useful life probability density function is explained and a cautionary argument is provided against mixing interpretations for the two while considering prognostics in making critical decisions.

Revealing Optical Components

NASA Technical Reports Server (NTRS)

2002-01-01

The Optical Vector Analyzer (OVA) 1550 significantly reduces the time and cost of testing sophisticated optical components. The technology grew from the research Luna Technologies' Dr. Mark Froggatt conducted on optical fiber strain measurement while working at Langley Research Center. Dr. Froggatt originally developed the technology for non- destructive evaluation testing at Langley. The new technique can provide 10,000 independent strain measurements while adding less than 10 grams to the weight of the vehicle. The OVA is capable of complete linear characterization of single-mode optical components used in high- bit-rate applications. The device can test most components over their full range in less than 30 seconds, compared to the more than 20 minutes required by other testing methods. The dramatically shortened measurement time results in increased efficiency in final acceptance tests of optical devices, and the comprehensive data produced by the instrument adds considerable value for component consumers. The device eliminates manufacturing bottlenecks, while reducing labor costs and wasted materials during production.

Constraining the instantaneous aerosol influence on cloud albedo

DOE PAGES

Gryspeerdt, Edward; Quaas, Johannes; Ferrachat, Sylvaine; ...

2017-04-26

Much of the uncertainty in estimates of the anthropogenic forcing of climate change comes from uncertainties in the instantaneous effect of aerosols on cloud albedo, known as the Twomey effect or the radiative forcing from aerosol–cloud interactions (RFaci), a component of the total or effective radiative forcing. Because aerosols serving as cloud condensation nuclei can have a strong influence on the cloud droplet number concentration ( N d), previous studies have used the sensitivity of the N d to aerosol properties as a constraint on the strength of the RFaci. However, recent studies have suggested that relationships between aerosol andmore » cloud properties in the present-day climate may not be suitable for determining the sensitivity of the N d to anthropogenic aerosol perturbations. Using an ensemble of global aerosol–climate models, this study demonstrates how joint histograms between N d and aerosol properties can account for many of the issues raised by previous studies. It shows that if the anthropogenic contribution to the aerosol is known, the RFaci can be diagnosed to within 20% of its actual value. Furthermore, the accuracy of different aerosol proxies for diagnosing the RFaci is investigated, confirming that using the aerosol optical depth significantly underestimates the strength of the aerosol–cloud interactions in satellite data.« less

Constraining the instantaneous aerosol influence on cloud albedo

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gryspeerdt, Edward; Quaas, Johannes; Ferrachat, Sylvaine

Much of the uncertainty in estimates of the anthropogenic forcing of climate change comes from uncertainties in the instantaneous effect of aerosols on cloud albedo, known as the Twomey effect or the radiative forcing from aerosol–cloud interactions (RFaci), a component of the total or effective radiative forcing. Because aerosols serving as cloud condensation nuclei can have a strong influence on the cloud droplet number concentration ( N d), previous studies have used the sensitivity of the N d to aerosol properties as a constraint on the strength of the RFaci. However, recent studies have suggested that relationships between aerosol andmore » cloud properties in the present-day climate may not be suitable for determining the sensitivity of the N d to anthropogenic aerosol perturbations. Using an ensemble of global aerosol–climate models, this study demonstrates how joint histograms between N d and aerosol properties can account for many of the issues raised by previous studies. It shows that if the anthropogenic contribution to the aerosol is known, the RFaci can be diagnosed to within 20% of its actual value. Furthermore, the accuracy of different aerosol proxies for diagnosing the RFaci is investigated, confirming that using the aerosol optical depth significantly underestimates the strength of the aerosol–cloud interactions in satellite data.« less

Measurement system for diffraction efficiency of convex gratings

NASA Astrophysics Data System (ADS)

Liu, Peng; Chen, Xin-hua; Zhou, Jian-kang; Zhao, Zhi-cheng; Liu, Quan; Luo, Chao; Wang, Xiao-feng; Tang, Min-xue; Shen, Wei-min

2017-08-01

A measurement system for diffraction efficiency of convex gratings is designed. The measurement system mainly includes four components as a light source, a front system, a dispersing system that contains a convex grating, and a detector. Based on the definition and measuring principle of diffraction efficiency, the optical scheme of the measurement system is analyzed and the design result is given. Then, in order to validate the feasibility of the designed system, the measurement system is set up and the diffraction efficiency of a convex grating with the aperture of 35 mm, the curvature-radius of 72mm, the blazed angle of 6.4°, the grating period of 2.5μm and the working waveband of 400nm-900nm is tested. Based on GUM (Guide to the Expression of Uncertainty in Measurement), the uncertainties in the measuring results are evaluated. The measured diffraction efficiency data are compared to the theoretical ones, which are calculated based on the grating groove parameters got by an atomic force microscope and Rigorous Couple Wave Analysis, and the reliability of the measurement system is illustrated. Finally, the measurement performance of the system is analyzed and tested. The results show that, the testing accuracy, the testing stability and the testing repeatability are 2.5%, 0.085% and 3.5% , respectively.

The Solar X-Ray Limb

NASA Astrophysics Data System (ADS)

Battaglia, Marina; Hudson, Hugh S.; Hurford, Gordon J.; Krucker, Säm; Schwartz, Richard A.

2017-07-01

We describe a new technique to measure the height of the X-ray limb with observations from occulted X-ray flare sources as observed by the RHESSI (the Reuven Ramaty High-Energy Spectroscopic Imager) satellite. This method has model dependencies different from those present in traditional observations at optical wavelengths, which depend upon detailed modeling involving radiative transfer in a medium with complicated geometry and flows. It thus provides an independent and more rigorous measurement of the “true” solar radius, which means that of the mass distribution. RHESSI’s measurement makes use of the flare X-ray source’s spatial Fourier components (the visibilities), which are sensitive to the presence of the sharp edge at the lower boundary of the occulted source. We have found a suitable flare event for analysis, SOL2011-10-20T03:25 (M1.7), and report a first result from this novel technique here. Using a four-minute integration over the 3-25 keV photon energy range, we find {R}{{X} - {ray}}=960.11+/- 0.15+/- 0.29 arcsec, at 1 au, where the uncertainties include statistical uncertainties from the method and a systematic error. The standard VAL-C model predicts a value of 959.94 arcsec, which is about 1σ below our value.

Constraining the instantaneous aerosol influence on cloud albedo

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gryspeerdt, Edward; Quaas, Johannes; Ferrachat, Sylvaine

2017-04-26

Much of the uncertainty in estimates of the anthropogenic forcing of climate change comes from uncertainties in the instantaneous effect of aerosols on cloud albedo, known as the Twomey effect or the radiative forcing from aerosol–cloud interactions (RFaci), a component of the total or effective radiative forcing. Because aerosols serving as cloud condensation nuclei can have a strong influence on the cloud droplet number concentration (Nd), previous studies have used the sensitivity of the Nd to aerosol properties as a constraint on the strength of the RFaci. However, recent studies have suggested that relationships between aerosol and cloud properties inmore » the present-day climate may not be suitable for determining the sensitivity of the Nd to anthropogenic aerosol perturbations. Using an ensemble of global aerosol–climate models, this study demonstrates how joint histograms between Nd and aerosol properties can account for many of the issues raised by previous studies. It shows that if the anthropogenic contribution to the aerosol is known, the RFaci can be diagnosed to within 20% of its actual value. The accuracy of different aerosol proxies for diagnosing the RFaci is investigated, confirming that using the aerosol optical depth significantly underestimates the strength of the aerosol–cloud interactions in satellite data.« less

How accurately can the instantaneous aerosol effect on cloud albedo be constrained?

NASA Astrophysics Data System (ADS)

Gryspeerdt, E.; Quaas, J.; Ferrachat, S.; Gettelman, A.; Ghan, S. J.; Lohmann, U.; Neubauer, D.; Morrison, H.; Partridge, D.; Stier, P.; Takemura, T.; Wang, H.; Wang, M.; Zhang, K.

2017-12-01

Aerosol-cloud interactions are the most uncertain component of the anthropogenic radiative forcing, with a significant fraction of this uncertainty coming from uncertainty in the radiative forcing due to instantaneous changes in cloud albedo (the RFaci). Aerosols can have a strong influence on the cloud droplet number concentration (CDNC), so previous studies have used the sensitivity of CDNC to aerosol properties as a method of estimating the RFaci. However, recent studies have suggested that this sensitivity is unsuitable as a constraint on the RFaci, as it differs in the present day and pre-industrial atmosphere. This would place significant limits on our ability to constrain the RFaci from satellite observations. In this study, a selection of global aerosol-climate models are used to investigate the suitability of various aerosol proxies and methods for calculating the RFaci from present day data. A linear-regression based sensitivity of CDNC to aerosol perturbations can lead to large errors in the diagnosed RFaci, as can the use of the aerosol optical depth (AOD) as an aerosol proxy. However, we show that if suitable choices of aerosol proxy are made and the anthropogenic aerosol contribution is known, it is possible to diagnose the anthropogenic change in CDNC, and so the RFaci, using present day aerosol-cloud relationships.

Constraining the instantaneous aerosol influence on cloud albedo.

PubMed

Gryspeerdt, Edward; Quaas, Johannes; Ferrachat, Sylvaine; Gettelman, Andrew; Ghan, Steven; Lohmann, Ulrike; Morrison, Hugh; Neubauer, David; Partridge, Daniel G; Stier, Philip; Takemura, Toshihiko; Wang, Hailong; Wang, Minghuai; Zhang, Kai

2017-05-09

Much of the uncertainty in estimates of the anthropogenic forcing of climate change comes from uncertainties in the instantaneous effect of aerosols on cloud albedo, known as the Twomey effect or the radiative forcing from aerosol-cloud interactions (RFaci), a component of the total or effective radiative forcing. Because aerosols serving as cloud condensation nuclei can have a strong influence on the cloud droplet number concentration ( N d ), previous studies have used the sensitivity of the N d to aerosol properties as a constraint on the strength of the RFaci. However, recent studies have suggested that relationships between aerosol and cloud properties in the present-day climate may not be suitable for determining the sensitivity of the N d to anthropogenic aerosol perturbations. Using an ensemble of global aerosol-climate models, this study demonstrates how joint histograms between N d and aerosol properties can account for many of the issues raised by previous studies. It shows that if the anthropogenic contribution to the aerosol is known, the RFaci can be diagnosed to within 20% of its actual value. The accuracy of different aerosol proxies for diagnosing the RFaci is investigated, confirming that using the aerosol optical depth significantly underestimates the strength of the aerosol-cloud interactions in satellite data.

Measuring centimeter-resolution air temperature profiles above land and water using fiber-optic Distributed Temperature Sensing

NASA Astrophysics Data System (ADS)

Sigmund, Armin; Pfister, Lena; Olesch, Johannes; Thomas, Christoph K.

2016-04-01

The precise determination of near-surface air temperature profiles is of special importance for the characterization of airflows (e.g. cold air) and the quantification of sensible heat fluxes according to the flux-gradient similarity approach. In contrast to conventional multi-sensor techniques, measuring temperature profiles using fiber-optic Distributed Temperature Sensing (DTS) provides thousands of measurements referenced to a single calibration standard at much reduced costs. The aim of this work was to enhance the vertical resolution of Raman scatter DTS measurements up to the centimeter-scale using a novel approach for atmospheric applications: the optical fiber was helically coiled around a meshed fabric. In addition to testing the new fiber geometry, we quantified the measurement uncertainty and demonstrated the benefits of the enhanced-resolution profiles. The fiber-optic cable was coiled around a hollow column consisting of white reinforcing fabric supported by plexiglass rings every meter. Data from two columns of this type were collected for 47 days to measure air temperature vertically over 3.0 and 5.1 m over a gently inclined meadow and over and in a small lake, respectively. Both profiles had a vertical resolution of 1 cm in the lower section near the surface and 5 cm in the upper section with an along-fiber instrument-specific averaging of 1.0 m and a temporal resolution of 30 s. Measurement uncertainties, especially from conduction between reinforcing fabric and fiber-optic cable, were estimated by modeling the fiber temperature via a detailed energy balance approach. Air temperature, wind velocity and radiation components were needed as input data and measured separately. The temperature profiles revealed valuable details, especially in the lowest 1 m above surface. This was best demonstrated for nighttime observations when artefacts due to solar heating did not occur. For example, the dynamics of a cold air layer was detected in a clear night with weak wind. In the same night temperature gradients up to 30 K m-1 were determined above the meadow. The water was up to 13 K warmer than the air in this night resulting in a sharp and strong temperature decrease at the water surface and a moderate decrease with gradients up to -9 K m-1 in the air above. The plexiglass rings caused some obvious artefacts and affected data was removed and replaced by linear interpolation. According to the uncertainty estimation performed to date, conduction between fabric and fiber increased fiber temperatures by approximately 0.005 K at 2 m height on a sunny day with weak wind. This effect was deemed negligible as it reflected less than 1 % of the total heating compared to that in the air. The maximum absolute error was approximately 0.9 K at 2 m height on the same day. Ongoing work will demonstrate potential benefits of the enhanced-resolution profiles by quantitatively comparing measured and interpolated temperature profiles with varying resolution (as well as sensible heat fluxes computed according to flux-gradient-similarity).

Computational Fluid Dynamics Uncertainty Analysis for Payload Fairing Spacecraft Environmental Control Systems

NASA Technical Reports Server (NTRS)

Groves, Curtis; Ilie, Marcel; Schallhorn, Paul

2014-01-01

Spacecraft components may be damaged due to airflow produced by Environmental Control Systems (ECS). There are uncertainties and errors associated with using Computational Fluid Dynamics (CFD) to predict the flow field around a spacecraft from the ECS System. This paper describes an approach to estimate the uncertainty in using CFD to predict the airflow speeds around an encapsulated spacecraft.

DRAINMOD-GIS: a lumped parameter watershed scale drainage and water quality model

Treesearch

G.P. Fernandez; G.M. Chescheir; R.W. Skaggs; D.M. Amatya

2006-01-01

A watershed scale lumped parameter hydrology and water quality model that includes an uncertainty analysis component was developed and tested on a lower coastal plain watershed in North Carolina. Uncertainty analysis was used to determine the impacts of uncertainty in field and network parameters of the model on the predicted outflows and nitrate-nitrogen loads at the...

Evaluating critical uncertainty thresholds in a spatial model of forest pest invasion risk

Treesearch

Frank H. Koch; Denys Yemshanov; Daniel W. McKenney; William D. Smith

2009-01-01

Pest risk maps can provide useful decision support in invasive species management, but most do not adequately consider the uncertainty associated with predicted risk values. This study explores how increased uncertainty in a risk model’s numeric assumptions might affect the resultant risk map. We used a spatial stochastic model, integrating components for...

Dispelling urban myths about default uncertainty factors in chemical risk assessment – sufficient protection against mixture effects?

PubMed Central

2013-01-01

Assessing the detrimental health effects of chemicals requires the extrapolation of experimental data in animals to human populations. This is achieved by applying a default uncertainty factor of 100 to doses not found to be associated with observable effects in laboratory animals. It is commonly assumed that the toxicokinetic and toxicodynamic sub-components of this default uncertainty factor represent worst-case scenarios and that the multiplication of those components yields conservative estimates of safe levels for humans. It is sometimes claimed that this conservatism also offers adequate protection from mixture effects. By analysing the evolution of uncertainty factors from a historical perspective, we expose that the default factor and its sub-components are intended to represent adequate rather than worst-case scenarios. The intention of using assessment factors for mixture effects was abandoned thirty years ago. It is also often ignored that the conservatism (or otherwise) of uncertainty factors can only be considered in relation to a defined level of protection. A protection equivalent to an effect magnitude of 0.001-0.0001% over background incidence is generally considered acceptable. However, it is impossible to say whether this level of protection is in fact realised with the tolerable doses that are derived by employing uncertainty factors. Accordingly, it is difficult to assess whether uncertainty factors overestimate or underestimate the sensitivity differences in human populations. It is also often not appreciated that the outcome of probabilistic approaches to the multiplication of sub-factors is dependent on the choice of probability distributions. Therefore, the idea that default uncertainty factors are overly conservative worst-case scenarios which can account both for the lack of statistical power in animal experiments and protect against potential mixture effects is ill-founded. We contend that precautionary regulation should provide an incentive to generate better data and recommend adopting a pragmatic, but scientifically better founded approach to mixture risk assessment. PMID:23816180

Dispelling urban myths about default uncertainty factors in chemical risk assessment--sufficient protection against mixture effects?

PubMed

Martin, Olwenn V; Martin, Scholze; Kortenkamp, Andreas

2013-07-01

Assessing the detrimental health effects of chemicals requires the extrapolation of experimental data in animals to human populations. This is achieved by applying a default uncertainty factor of 100 to doses not found to be associated with observable effects in laboratory animals. It is commonly assumed that the toxicokinetic and toxicodynamic sub-components of this default uncertainty factor represent worst-case scenarios and that the multiplication of those components yields conservative estimates of safe levels for humans. It is sometimes claimed that this conservatism also offers adequate protection from mixture effects. By analysing the evolution of uncertainty factors from a historical perspective, we expose that the default factor and its sub-components are intended to represent adequate rather than worst-case scenarios. The intention of using assessment factors for mixture effects was abandoned thirty years ago. It is also often ignored that the conservatism (or otherwise) of uncertainty factors can only be considered in relation to a defined level of protection. A protection equivalent to an effect magnitude of 0.001-0.0001% over background incidence is generally considered acceptable. However, it is impossible to say whether this level of protection is in fact realised with the tolerable doses that are derived by employing uncertainty factors. Accordingly, it is difficult to assess whether uncertainty factors overestimate or underestimate the sensitivity differences in human populations. It is also often not appreciated that the outcome of probabilistic approaches to the multiplication of sub-factors is dependent on the choice of probability distributions. Therefore, the idea that default uncertainty factors are overly conservative worst-case scenarios which can account both for the lack of statistical power in animal experiments and protect against potential mixture effects is ill-founded. We contend that precautionary regulation should provide an incentive to generate better data and recommend adopting a pragmatic, but scientifically better founded approach to mixture risk assessment.

Thermospheric mass density model error variance as a function of time scale

NASA Astrophysics Data System (ADS)

Emmert, J. T.; Sutton, E. K.

2017-12-01

In the increasingly crowded low-Earth orbit environment, accurate estimation of orbit prediction uncertainties is essential for collision avoidance. Poor characterization of such uncertainty can result in unnecessary and costly avoidance maneuvers (false positives) or disregard of a collision risk (false negatives). Atmospheric drag is a major source of orbit prediction uncertainty, and is particularly challenging to account for because it exerts a cumulative influence on orbital trajectories and is therefore not amenable to representation by a single uncertainty parameter. To address this challenge, we examine the variance of measured accelerometer-derived and orbit-derived mass densities with respect to predictions by thermospheric empirical models, using the data-minus-model variance as a proxy for model uncertainty. Our analysis focuses mainly on the power spectrum of the residuals, and we construct an empirical model of the variance as a function of time scale (from 1 hour to 10 years), altitude, and solar activity. We find that the power spectral density approximately follows a power-law process but with an enhancement near the 27-day solar rotation period. The residual variance increases monotonically with altitude between 250 and 550 km. There are two components to the variance dependence on solar activity: one component is 180 degrees out of phase (largest variance at solar minimum), and the other component lags 2 years behind solar maximum (largest variance in the descending phase of the solar cycle).

Flowers help bees cope with uncertainty: signal detection and the function of floral complexity

PubMed Central

Leonard, Anne S.; Dornhaus, Anna; Papaj, Daniel R.

2011-01-01

Plants often attract pollinators with floral displays composed of visual, olfactory, tactile and gustatory stimuli. Since pollinators' responses to each of these stimuli are usually studied independently, the question of why plants produce multi-component floral displays remains relatively unexplored. Here we used signal detection theory to test the hypothesis that complex displays reduce a pollinator's uncertainty about the floral signal. Specifically, we asked whether one component of the floral display, scent, improved a bee's certainty about the value of another component, color hue. We first trained two groups of bumble bees (Bombus impatiens Cresson) to discriminate between rewarding and unrewarding artificial flowers of slightly different hues in the presence vs absence of scent. In a test phase, we presented these bees with a gradient of floral hues and assessed their ability to identify the hue rewarded during training. We interpreted the extent to which bees' preferences were biased away from the unrewarding hue (‘peak shift’) as an indicator of uncertainty in color discrimination. Our data show that the presence of an olfactory signal reduces uncertainty regarding color: not only was color learning facilitated on scented flowers but also bees showed a lower amount of peak shift in the presence of scent. We explore potential mechanisms by which scent might reduce uncertainty about color, and discuss the broader significance of our results for our understanding of signal evolution. PMID:21147975

An uncertainty analysis for satellite-based estimates of cloud condensation nuclei number concentrations

NASA Astrophysics Data System (ADS)

Shinozuka, Y.; Clarke, A. D.; Nenes, A.; Jefferson, A.; Wood, R.; McNaughton, C. S.; Ström, J.; Tunved, P.; Redemann, J.; Thornhill, K. L., II; Moore, R.; Lathem, T. L.; Lin, J.; Yoon, Y. J.

2017-12-01

Aerosol-cloud interactions (ACI) are the largest source of uncertainty in estimates of anthropogenic radiative forcing responsible for the on-going climate change. ACI for warm clouds depend on the number concentration of cloud condensation nuclei (CCN), not on aerosol optical properties. Yet, aerosol optical depth (AOD) and its variants weighted by the spectral dependence over visible and near infrared wavelengths are commonly substituted for CCN in ACI studies. The substitution is motivated by the wide availability in space and time of satellite retrievals, an advantage over the sparse CCN measurements. If satellite-based CCN estimates are to continue to complement purely model-based ones, what CCN-AOD relationship should we assume and how large is the associated uncertainty? Our 2015 paper examines airborne and ground-based observations of aerosols to address these questions, focusing on the relationship between CCN and light extinction, σ, of dried particles averaged over one-kilometer horizontal distance. That paper discusses the way the CCN-AOD relationship is influenced not only by the CCN-σ relationship but also by the humidity response of light extinction, the vertical profile, the horizontal-temporal variability and the AOD measurement error. In this presentation, we apply these findings to passive satellite data to analyze the uncertainty in satellite-based CCN estimates.

Optical Fiber Power Meter Comparison Between NIST and NIM.

PubMed

Vayshenker, I; Livigni, D J; Li, X; Lehman, J H; Li, J; Xiong, L M; Zhang, Z X

2010-01-01

We describe the results of a comparison of reference standards between the National Institute of Standards and Technology (NIST-USA) and National Institute of Metrology (NIM-China). We report optical fiber-based power measurements at nominal wavelengths of 1310 nm and 1550 nm. We compare the laboratories' reference standards by means of a commercial optical power meter. Measurement results showed the largest difference of less than 2.6 parts in 10(3), which is within the combined standard (k = 1) uncertainty for the laboratories' reference standards.

Reducing Multisensor Satellite Monthly Mean Aerosol Optical Depth Uncertainty: 1. Objective Assessment of Current AERONET Locations

NASA Technical Reports Server (NTRS)

Li, Jing; Li, Xichen; Carlson, Barbara E.; Kahn, Ralph A.; Lacis, Andrew A.; Dubovik, Oleg; Nakajima, Teruyuki

2016-01-01

Various space-based sensors have been designed and corresponding algorithms developed to retrieve aerosol optical depth (AOD), the very basic aerosol optical property, yet considerable disagreement still exists across these different satellite data sets. Surface-based observations aim to provide ground truth for validating satellite data; hence, their deployment locations should preferably contain as much spatial information as possible, i.e., high spatial representativeness. Using a novel Ensemble Kalman Filter (EnKF)- based approach, we objectively evaluate the spatial representativeness of current Aerosol Robotic Network (AERONET) sites. Multisensor monthly mean AOD data sets from Moderate Resolution Imaging Spectroradiometer, Multiangle Imaging Spectroradiometer, Sea-viewing Wide Field-of-view Sensor, Ozone Monitoring Instrument, and Polarization and Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar are combined into a 605-member ensemble, and AERONET data are considered as the observations to be assimilated into this ensemble using the EnKF. The assessment is made by comparing the analysis error variance (that has been constrained by ground-based measurements), with the background error variance (based on satellite data alone). Results show that the total uncertainty is reduced by approximately 27% on average and could reach above 50% over certain places. The uncertainty reduction pattern also has distinct seasonal patterns, corresponding to the spatial distribution of seasonally varying aerosol types, such as dust in the spring for Northern Hemisphere and biomass burning in the fall for Southern Hemisphere. Dust and biomass burning sites have the highest spatial representativeness, rural and oceanic sites can also represent moderate spatial information, whereas the representativeness of urban sites is relatively localized. A spatial score ranging from 1 to 3 is assigned to each AERONET site based on the uncertainty reduction, indicating its representativeness level.

Multimode fiber optic wavelength division multiplexing

NASA Technical Reports Server (NTRS)

Spencer, J. L.

1982-01-01

Optical wavelength division multiplexing (WDM) systems, with signals transmitted on different wavelengths through a single optical fiber, can have increased bandwidth and fault isolation properties over single wavelength optical systems. Two WDM system designs that might be used with multimode fibers are considered and a general description of the components which could be used to implement the system are given. The components described are sources, multiplexers, demultiplexers, and detectors. Emphasis is given to the demultiplexer technique which is the major developmental component in the WDM system.

Modeling uncertainty: quicksand for water temperature modeling

USGS Publications Warehouse

Bartholow, John M.

2003-01-01

Uncertainty has been a hot topic relative to science generally, and modeling specifically. Modeling uncertainty comes in various forms: measured data, limited model domain, model parameter estimation, model structure, sensitivity to inputs, modelers themselves, and users of the results. This paper will address important components of uncertainty in modeling water temperatures, and discuss several areas that need attention as the modeling community grapples with how to incorporate uncertainty into modeling without getting stuck in the quicksand that prevents constructive contributions to policy making. The material, and in particular the reference, are meant to supplement the presentation given at this conference.

Visual Semiotics & Uncertainty Visualization: An Empirical Study.

PubMed

MacEachren, A M; Roth, R E; O'Brien, J; Li, B; Swingley, D; Gahegan, M

2012-12-01

This paper presents two linked empirical studies focused on uncertainty visualization. The experiments are framed from two conceptual perspectives. First, a typology of uncertainty is used to delineate kinds of uncertainty matched with space, time, and attribute components of data. Second, concepts from visual semiotics are applied to characterize the kind of visual signification that is appropriate for representing those different categories of uncertainty. This framework guided the two experiments reported here. The first addresses representation intuitiveness, considering both visual variables and iconicity of representation. The second addresses relative performance of the most intuitive abstract and iconic representations of uncertainty on a map reading task. Combined results suggest initial guidelines for representing uncertainty and discussion focuses on practical applicability of results.

Electro-optical equivalent calibration technology for high-energy laser energy meters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wei, Ji Feng, E-mail: wjfcom2000@163.com; Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900; Graduate School of China Academy of Engineering Physics, Beijing 100088

Electro-optical equivalent calibration with high calibration power and high equivalence is particularly well-suited to the calibration of high-energy laser energy meters. A large amount of energy is reserved during this process, however, which continues to radiate after power-off. This study measured the radiation efficiency of a halogen tungsten lamp during power-on and after power-off in order to calculate the total energy irradiated by a lamp until the high-energy laser energy meter reaches thermal equilibrium. A calibration system was designed based on the measurement results, and the calibration equivalence of the system was analyzed in detail. Results show that measurement precisionmore » is significantly affected by the absorption factor of the absorption chamber and by heat loss in the energy meter. Calibration precision is successfully improved by enhancing the equivalent power and reducing power-on time. The electro-optical equivalent calibration system, measurement uncertainty of which was evaluated as 2.4% (k = 2), was used to calibrate a graphite-cone-absorption-cavity absolute energy meter, yielding a calibration coefficient of 1.009 and measurement uncertainty of 3.5% (k = 2). A water-absorption-type high-energy laser energy meter with measurement uncertainty of 4.8% (k = 2) was considered the reference standard, and compared to the energy meter calibrated in this study, yielded a correction factor of 0.995 (standard deviation of 1.4%).« less

Expected Improvements in the Quantitative Remote Sensing of Optically Complex Waters with the Use of an Optically Fast Hyperspectral Spectrometer—A Modeling Study

PubMed Central

Moses, Wesley J.; Bowles, Jeffrey H.; Corson, Michael R.

2015-01-01

Using simulated data, we investigated the effect of noise in a spaceborne hyperspectral sensor on the accuracy of the atmospheric correction of at-sensor radiances and the consequent uncertainties in retrieved water quality parameters. Specifically, we investigated the improvement expected as the F-number of the sensor is changed from 3.5, which is the smallest among existing operational spaceborne hyperspectral sensors, to 1.0, which is foreseeable in the near future. With the change in F-number, the uncertainties in the atmospherically corrected reflectance decreased by more than 90% across the visible-near-infrared spectrum, the number of pixels with negative reflectance (caused by over-correction) decreased to almost one-third, and the uncertainties in the retrieved water quality parameters decreased by more than 50% and up to 92%. The analysis was based on the sensor model of the Hyperspectral Imager for the Coastal Ocean (HICO) but using a 30-m spatial resolution instead of HICO’s 96 m. Atmospheric correction was performed using Tafkaa. Water quality parameters were retrieved using a numerical method and a semi-analytical algorithm. The results emphasize the effect of sensor noise on water quality parameter retrieval and the need for sensors with high Signal-to-Noise Ratio for quantitative remote sensing of optically complex waters. PMID:25781507

Airborne Sun Photometer Measurements of Aerosol Optical Depth during SOLVE II: Comparison with SAGE III and POAM III Measurements

NASA Technical Reports Server (NTRS)

Russell, P.; Livingston, J.; Schmid, B.; Eilers, J.; Kolyer, R.; Redemann, J.; Yee, J.-H.; Trepte, C.; Thomason, L.; Zawodny, J.

2003-01-01

The 14-channel NASA Ames Airborne Tracking Sunphotometer (AATS-14) was operated aboard the NASA DC-8 during the Second SAGE III Ozone Loss and Validation Experiment (SOLVE II) and obtained successful measurements during the sunlit segments of eight science flights. These included six flights out of Kiruna, Sweden, one flight out of NASA Dryden Flight Research Center (DFRC), and the Kiruna-DFRC return transit flight. Values of spectral aerosol optical depth (AOD), columnar ozone and columnar water vapor have been derived from the AATS-14 measurements. In this paper, we focus on AATS-14 AOD data. In particular, we compare AATS-14 AOD spectra with temporally and spatially near-coincident measurements by the Stratospheric Aerosol and Gas Experiment III (SAGE III) and the Polar Ozone and Aerosol Measurement III (POAM III) satellite sensors. We examine the effect on retrieved AOD of uncertainties in relative optical airmass (the ratio of AOD along the instrument-to-sun slant path to that along the vertical path) at large solar zenith angles. Airmass uncertainties result fiom uncertainties in requisite assumed vertical profiles of aerosol extinction due to inhomogeneity along the viewing path or simply to lack of available data. We also compare AATS-14 slant path solar transmission measurements with coincident measurements acquired from the DC-8 by the NASA Langley Research Center Gas and Aerosol Measurement Sensor (GAMS).

The Surface Brightness-color Relations Based on Eclipsing Binary Stars: Toward Precision Better than 1% in Angular Diameter Predictions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graczyk, Dariusz; Gieren, Wolfgang; Konorski, Piotr

In this study we investigate the calibration of surface brightness–color (SBC) relations based solely on eclipsing binary stars. We selected a sample of 35 detached eclipsing binaries with trigonometric parallaxes from Gaia DR1 or Hipparcos whose absolute dimensions are known with an accuracy better than 3% and that lie within 0.3 kpc from the Sun. For the purpose of this study, we used mostly homogeneous optical and near-infrared photometry based on the Tycho-2 and 2MASS catalogs. We derived geometric angular diameters for all stars in our sample with a precision better than 10%, and for 11 of them with amore » precision better than 2%. The precision of individual angular diameters of the eclipsing binary components is currently limited by the precision of the geometric distances (∼5% on average). However, by using a subsample of systems with the best agreement between their geometric and photometric distances, we derived the precise SBC relations based only on eclipsing binary stars. These relations have precisions that are comparable to the best available SBC relations based on interferometric angular diameters, and they are fully consistent with them. With very precise Gaia parallaxes becoming available in the near future, angular diameters with a precision better than 1% will be abundant. At that point, the main uncertainty in the total error budget of the SBC relations will come from transformations between different photometric systems, disentangling of component magnitudes, and for hot OB stars, the main uncertainty will come from the interstellar extinction determination. We argue that all these issues can be overcome with modern high-quality data and conclude that a precision better than 1% is entirely feasible.« less

Optical Path Switching Based Differential Absorption Radiometry for Substance Detection

NASA Technical Reports Server (NTRS)

Sachse, Glen W. (Inventor)

2000-01-01

A system and method are provided for detecting one or more substances. An optical path switch divides sample path radiation into a time series of alternating first polarized components and second polarized components. The first polarized components are transmitted along a first optical path and the second polarized components along a second optical path. A first gasless optical filter train filters the first polarized components to isolate at least a first wavelength band thereby generating first filtered radiation. A second gasless optical filter train filters the second polarized components to isolate at least a second wavelength band thereby generating second filtered radiation. The first wavelength band and second wavelength band are unique. Further, spectral absorption of a substance of interest is different at the first wavelength band as compared to the second wavelength band. A beam combiner combines the first and second filtered radiation to form a combined beam of radiation. A detector is disposed to monitor magnitude of at least a portion of the combined beam alternately at the first wavelength band and the second wavelength band as an indication of the concentration of the substance in the sample path.

Embedding Optical Fibers In Cast Metal Parts

NASA Technical Reports Server (NTRS)

Gibler, William N.; Atkins, Robert A.; Lee, Chung E.; Taylor, Henry F.

1995-01-01

Use of metal strain reliefs eliminates breakage of fibers during casting process. Technique for embedding fused silica optical fibers in cast metal parts devised. Optical fiber embedded in flange, fitting, or wall of vacuum or pressure chamber, to provide hermetically sealed feedthrough for optical transmission of measurement or control signals. Another example, optical-fiber temperature sensor embedded in metal structural component to measure strain or temperature inside component.

Performance Characterization of Digital Optical Data Transfer Systems for Use in the Space Radiation Environment

NASA Technical Reports Server (NTRS)

Reed, Robert A.; Ladbury, Ray L.; Day, John H. (Technical Monitor)

2000-01-01

Radiation effects in photonic and microelectronic components can impact the performance of high-speed digital optical data link in a variety of ways. This segment of the short course focuses on radiation effects in digital optical data links operating in the MHz to GHz regime. (Some of the information is applicable to frequencies above and below this regime) The three basic component level effects that should be considered are Total Ionizing Dose (TID), Displacement Damage Dose (DDD) and Single Event Effects (SEE). In some cases the system performance degradation can be quantified from component level tests, while in others a more holistic characterization approach must be taken. In Section 2.0 of this segment of the Short Course we will give a brief overview of the space radiation environment follow by a summary of the basic space radiation effects important for microelectronics and photonics listed above. The last part of this section will give an example of a typical mission radiation environment requirements. Section 3.0 gives an overview of intra-satellite digital optical data link systems. It contains a discussion of the digital optical data link and it's components. Also, we discuss some of the important system performance metrics that are impacted by radiation effects degradation of optical and optoelectronic component performance. Section 4.0 discusses radiation effects in optical and optoelectronic components. While each component effect will be discussed, the focus of this section is on degradation of passive optical components and SEE in photodiodes (other mechanisms are covered in segment II of this short course entitled "Photonic Devices with Complex and Multiple Failure Modes"). Section 5.0 will focus on optical data link system response to the space radiation environment. System level SEE ground testing will be discussed. Then we give a discussion of system level assessment of data link performance when operating in the space radiation environment.

Integration of Component Knowledge in Penalized-Likelihood Reconstruction with Morphological and Spectral Uncertainties.

PubMed

Stayman, J Webster; Tilley, Steven; Siewerdsen, Jeffrey H

2014-01-01

Previous investigations [1-3] have demonstrated that integrating specific knowledge of the structure and composition of components like surgical implants, devices, and tools into a model-based reconstruction framework can improve image quality and allow for potential exposure reductions in CT. Using device knowledge in practice is complicated by uncertainties in the exact shape of components and their particular material composition. Such unknowns in the morphology and attenuation properties lead to errors in the forward model that limit the utility of component integration. In this work, a methodology is presented to accommodate both uncertainties in shape as well as unknown energy-dependent attenuation properties of the surgical devices. This work leverages the so-called known-component reconstruction (KCR) framework [1] with a generalized deformable registration operator and modifications to accommodate a spectral transfer function in the component model. Moreover, since this framework decomposes the object into separate background anatomy and "known" component factors, a mixed fidelity forward model can be adopted so that measurements associated with projections through the surgical devices can be modeled with much greater accuracy. A deformable KCR (dKCR) approach using the mixed fidelity model is introduced and applied to a flexible wire component with unknown structure and composition. Image quality advantages of dKCR over traditional reconstruction methods are illustrated in cone-beam CT (CBCT) data acquired on a testbench emulating a 3D-guided needle biopsy procedure - i.e., a deformable component (needle) with strong energy-dependent attenuation characteristics (steel) within a complex soft-tissue background.

The Dependence of Cloud Property Trend Detection on Absolute Calibration Accuracy of Passive Satellite Sensors

NASA Astrophysics Data System (ADS)

Shea, Y.; Wielicki, B. A.; Sun-Mack, S.; Minnis, P.; Zelinka, M. D.

2016-12-01

Detecting trends in climate variables on global, decadal scales requires highly accurate, stable measurements and retrieval algorithms. Trend uncertainty depends on its magnitude, natural variability, and instrument and retrieval algorithm accuracy and stability. We applied a climate accuracy framework to quantify the impact of absolute calibration on cloud property trend uncertainty. The cloud properties studied were cloud fraction, effective temperature, optical thickness, and effective radius retrieved using the Clouds and the Earth's Radiant Energy System (CERES) Cloud Property Retrieval System, which uses Moderate-resolution Imaging Spectroradiometer measurements (MODIS). Modeling experiments from the fifth phase of the Climate Model Intercomparison Project (CMIP5) agree that net cloud feedback is likely positive but disagree regarding its magnitude, mainly due to uncertainty in shortwave cloud feedback. With the climate accuracy framework we determined the time to detect trends for instruments with various calibration accuracies. We estimated a relationship between cloud property trend uncertainty, cloud feedback, and Equilibrium Climate Sensitivity and also between effective radius trend uncertainty and aerosol indirect effect trends. The direct relationship between instrument accuracy requirements and climate model output provides the level of instrument absolute accuracy needed to reduce climate model projection uncertainty. Different cloud types have varied radiative impacts on the climate system depending on several attributes, such as their thermodynamic phase, altitude, and optical thickness. Therefore, we also conducted these studies by cloud types for a clearer understanding of instrument accuracy requirements needed to detect changes in their cloud properties. Combining this information with the radiative impact of different cloud types helps to prioritize among requirements for future satellite sensors and understanding the climate detection capabilities of existing sensors.

AEROFROSH: a shock condition calculator for multi-component fuel aerosol-laden flows

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campbell, Matthew Frederick; Haylett, D. R.; Davidson, D. F.

Here, this paper introduces an algorithm that determines the thermodynamic conditions behind incident and reflectedshocksinaerosol-ladenflows.Importantly,the algorithm accounts for the effects of droplet evaporation on post-shock properties. Additionally, this article describes an algorithm for resolving the effects of multiple-component- fuel droplets. This article presents the solution methodology and compares the results to those of another similar shock calculator. It also provides examples to show the impact of droplets on post-shock properties and the impact that multi-component fuel droplets have on shock experimental parameters. Finally, this paper presents a detailed uncertainty analysis of this algorithm’s calculations given typical exper- imental uncertainties

AEROFROSH: a shock condition calculator for multi-component fuel aerosol-laden flows

DOE PAGES

Campbell, Matthew Frederick; Haylett, D. R.; Davidson, D. F.; ...

2015-08-18

Here, this paper introduces an algorithm that determines the thermodynamic conditions behind incident and reflectedshocksinaerosol-ladenflows.Importantly,the algorithm accounts for the effects of droplet evaporation on post-shock properties. Additionally, this article describes an algorithm for resolving the effects of multiple-component- fuel droplets. This article presents the solution methodology and compares the results to those of another similar shock calculator. It also provides examples to show the impact of droplets on post-shock properties and the impact that multi-component fuel droplets have on shock experimental parameters. Finally, this paper presents a detailed uncertainty analysis of this algorithm’s calculations given typical exper- imental uncertainties

Contributions of late-type dwarf stars to the soft X-ray diffuse background

NASA Technical Reports Server (NTRS)

Schmitt, J. H. M. M.; Snowden, S. L.

1990-01-01

Comprehensive calculations of the contribution of late-type dwarf stars to the soft X-ray diffuse background are presented. The mean X-ray luminosity as derived from optically and X-ray selected samples is examined, using the Bahcall-Soneira Galaxy model to describe the spatial distribution of stars and recent results on the X-ray spectra. The model calculations are compared with the Wisconsin sky maps in the C, M1, M2, I and J bands to assess the uncertainties of the calculations. Contributions of up to 10 percent to the M2 and I band background at high Galactic latitudes are found, while at low Galactic latitudes late-type stars contribute up to 40 percent of the background. However, a Galactic ridge as well as a relatively isotropic component still remains unexplained, even with the added contribution of the extrapolated high-energy power law.

Composition measurements of binary mixture droplets by rainbow refractometry.

PubMed

Wilms, J; Weigand, B

2007-04-10

So far, refractive index measurements by rainbow refractometry have been used to determine the temperature of single droplets and ensembles of droplets. Rainbow refractometry is, for the first time, to the best of our knowledge, applied to measure composition histories of evaporating, binary mixture droplets. An evaluation method is presented that makes use of Airy theory and the simultaneous size measurement by Mie scattering imaging. The method further includes an empirical correction function for a certain diameter and refractive index range. The measurement uncertainty was investigated by numerical simulations with Lorenz-Mie theory. For the experiments, an optical levitation setup was used allowing for long measurement periods. Temperature measurements of single-component droplets at different temperature levels are shown to demonstrate the accuracy of rainbow refractometry. Measurements of size and composition histories of binary mixture droplets are presented for two different mixtures. Experimental results show good agreement with numerical results using a rapid-mixing model.

[The uncertainty evaluation of analytical results of 27 elements in geological samples by X-ray fluorescence spectrometry].

PubMed

Wang, Yi-Ya; Zhan, Xiu-Chun

2014-04-01

Evaluating uncertainty of analytical results with 165 geological samples by polarized dispersive X-ray fluorescence spectrometry (P-EDXRF) has been reported according to the internationally accepted guidelines. One hundred sixty five pressed pellets of similar matrix geological samples with reliable values were analyzed by P-EDXRF. These samples were divided into several different concentration sections in the concentration ranges of every component. The relative uncertainties caused by precision and accuracy of 27 components were evaluated respectively. For one element in one concentration, the relative uncertainty caused by precision can be calculated according to the average value of relative standard deviation with different concentration level in one concentration section, n = 6 stands for the 6 results of one concentration level. The relative uncertainty caused by accuracy in one concentration section can be evaluated by the relative standard deviation of relative deviation with different concentration level in one concentration section. According to the error propagation theory, combining the precision uncertainty and the accuracy uncertainty into a global uncertainty, this global uncertainty acted as method uncertainty. This model of evaluating uncertainty can solve a series of difficult questions in the process of evaluating uncertainty, such as uncertainties caused by complex matrix of geological samples, calibration procedure, standard samples, unknown samples, matrix correction, overlap correction, sample preparation, instrument condition and mathematics model. The uncertainty of analytical results in this method can act as the uncertainty of the results of the similar matrix unknown sample in one concentration section. This evaluation model is a basic statistical method owning the practical application value, which can provide a strong base for the building of model of the following uncertainty evaluation function. However, this model used a lot of samples which cannot simply be applied to other types of samples with different matrix samples. The number of samples is too large to adapt to other type's samples. We will strive for using this study as a basis to establish a reasonable basis of mathematical statistics function mode to be applied to different types of samples.

Inference of Ice Cloud Properties from High-spectral Resolution Infrared Observations. Appendix 4

NASA Technical Reports Server (NTRS)

Huang, Hung-Lung; Yang, Ping; Wei, Heli; Baum, Bryan A.; Hu, Yongxiang; Antonelli, Paolo; Ackerman, Steven A.

2005-01-01

The theoretical basis is explored for inferring the microphysical properties of ice crystal from high-spectral resolution infrared observations. A radiative transfer model is employed to simulate spectral radiances to address relevant issues. The extinction and absorption efficiencies of individual ice crystals, assumed as hexagonal columns for large particles and droxtals for small particles, are computed from a combination of the finite- difference time-domain (FDTD) technique and a composite method. The corresponding phase functions are computed from a combination of FDTD and an improved geometric optics method (IGOM). Bulk scattering properties are derived by averaging the single- scattering properties of individual particles for 30 particle size distributions developed from in situ measurements and for additional four analytical Gamma size distributions for small particles. The non-sphericity of ice crystals is shown to have a significant impact on the radiative signatures in the infrared (IR) spectrum; the spherical particle approximation for inferring ice cloud properties may result in an overest&ation of the optical thickness and an inaccurate retrieval of effective particle size. Furthermore, we show that the error associated with the use of the Henyey-Greenstein phase function can be as larger as 1 K in terms of brightness temperature for larger particle effective size at some strong scattering wavenumbers. For small particles, the difference between the two phase functions is much less, with brightness temperatures generally differing by less than 0.4 K. The simulations undertaken in this study show that the slope of the IR brightness temperature spectrum between 790-960/cm is sensitive to the effective particle size. Furthermore, a strong sensitivity of IR brightness temperature to cloud optical thickness is noted within the l050-1250/cm region. Based on this spectral feature, a technique is presented for the simultaneous retrieval of the visible optical thickness and effective particle size from high spectral resolution infrared data under ice cloudy con&tion. The error analysis shows that the uncertainty of the retrieved optical thickness and effective particle size has a small range of variation. The error for retrieving particle size in conjunction with an uncertainty of 5 K in cloud'temperature, or a surface temperature uncertainty of 2.5 K, is less than 15%. The corresponding e m r in the uncertainty of optical thickness is within 5-2096, depending on the value of cloud optical thickness. The applicability of the technique is demonstrated using the aircraft-based High- resolution Interferometer Sounder (HIS) data from the Subsonic Aircraft: Contrail and Cloud Effects Special Study (SUCCESS) in 1996 and the First ISCCP Regional Experiment - Arctic Clouds Experiment (FIRE-ACE) in 1998.

Nonproliferation Uncertainties, a Major Barrier to Used Nuclear Fuel Recycle in the United States

DOE Office of Scientific and Technical Information (OSTI.GOV)

Collins, Emory D; Ehinger, Michael H

2011-01-01

A study and comparison of the goals and understandings of nonproliferation authorities with those of used nuclear fuel (UNF) recycle advocates have uncovered (1) some of the basic reasons for the creation of uncertainties by each of the parties, (2) why these uncertainties have become a major barrier to a decision to recycle UNF components in the United States, and (3) what steps can be taken to clarify these uncertainties. Recent papers and viewpoints expressed by nonproliferation authorities and technical consultants were reviewed, summarized, and compared with results of recent fuel cycle systems analyses made at Oak Ridge National Laboratory.more » 1 Similarities and differences were identified, including both technical and policy factors. Nonproliferation authorities and a few UNF recycle advocates have recognized that the reprocessing technologies used for UNF component recycle do not offer significant nonproliferation differences; thus, the methods used can be chosen on some other basis, such as process efficiency, maturity, and/or economics. This paper reviews the safeguards implications beyond the simple assessment of UNF recycle technology selection. Differences in understanding that led to uncertainty barriers to UNF recycle include (1) the vulnerability of unseparated UNF, (2) the effects of time factors on production and accumulation of fissile plutonium isotopes and decay of the ?self-protecting radiation barrier,? (3) the chemistry of UNF components and relative ease of separation, and (4) the significant differences in commercialscale ?safeguards-by-design? UNF recycle facilities and smaller-scale covert operations. Application of safeguards-by-design and engineered safeguards can provide the defense-in-depth necessary for sufficient safeguards. Establishing these requirements for governing acceptable commercial UNF component recycle is essential.« less

"Maybe the Algae Was from the Filter": Maybe and Similar Modifiers as Mediational Tools and Indicators of Uncertainty and Possibility in Children's Science Talk

ERIC Educational Resources Information Center

Kirch, Susan A.; Siry, Christina A.

2012-01-01

Uncertainty is an essential component of scientific inquiry and it also permeates our daily lives. Understanding how to identify, evaluate, resolve and live in the presence of uncertainty is important for decision-making strategies and engaging in transformative actions. In contrast, confidence and certainty are prized in elementary school…

Two different ways for waveguides and optoelectronics components on top of C-MOS

NASA Astrophysics Data System (ADS)

Fedeli, J. M.; Jeannot, S.; Kostrzewa, M.; Di Cioccio, L.; Jousseaume, V.; Orobtchouk, R.; Maury, P.; Zussy, M.

2006-02-01

While fabrication of photonic components at the wafer level is a long standing goal of integrated optics, new applications such as optical interconnects are introducing new challenges for waveguides and optoelectronic component fabrication. Indeed, global interconnects are expected to face severe limitations in the near future. To face this problem, optical links on top of a CMOS circuits could be an alternative. The critical points to perform an optical link on a chip are firstly the realization of compact passive optical distribution and secondly the report of optoelectronic components for the sources and detectors. This paper presents two different approaches for the integration of both waveguides and optoelectronic components. In a first "total bonding" approach, waveguides have been elaborated using classical "Silicon On Insulators" technology and then reported using molecular bonding on top off Si wafers. The S0I substrate was then chemically etched, after what InP dies were moleculary bonded on top of the waveguides. With this approach, optical components with low loses and a good equilibrium are demonsrated. Using molecular bonding, InP dies were reported with no degradation of the optoelectronic properties of the films. In a second approach, using PECVD silicon nitride or amorphous silicon coupled to PECVD silicon oxide, basic optical components are demonstrated. This low temperature technology is compatible with a microelectronic Back End process, allowing an integration of the waveguides directly on top of CMOS circuits. InP dies can then be bonded on top of the waveguides.

Design, fabrication and testing of hierarchical micro-optical structures and systems

NASA Astrophysics Data System (ADS)

Cannistra, Aaron Thomas

Micro-optical systems are becoming essential components in imaging, sensing, communications, computing, and other applications. Optically based designs are replacing electronic, chemical and mechanical systems for a variety of reasons, including low power consumption, reduced maintenance, and faster operation. However, as the number and variety of applications increases, micro-optical system designs are becoming smaller, more integrated, and more complicated. Micro and nano-optical systems found in nature, such as the imaging systems found in many insects and crustaceans, can have highly integrated optical structures that vary in size by orders of magnitude. These systems incorporate components such as compound lenses, anti-reflective lens surface structuring, spectral filters, and polarization selective elements. For animals, these hybrid optical systems capable of many optical functions in a compact package have been repeatedly selected during the evolutionary process. Understanding the advantages of these designs gives motivation for synthetic optical systems with comparable functionality. However, alternative fabrication methods that deviate from conventional processes are needed to create such systems. Further complicating the issue, the resulting device geometry may not be readily compatible with existing measurement techniques. This dissertation explores several nontraditional fabrication techniques for optical components with hierarchical geometries and measurement techniques to evaluate performance of such components. A micro-transfer molding process is found to produce high-fidelity micro-optical structures and is used to fabricate a spectral filter on a curved surface. By using a custom measurement setup we demonstrate that the spectral filter retains functionality despite the nontraditional geometry. A compound lens is fabricated using similar fabrication techniques and the imaging performance is analyzed. A spray coating technique for photoresist application to curved surfaces combined with interference lithography is also investigated. Using this technique, we generate polarizers on curved surfaces and measure their performance. This work furthers an understanding of how combining multiple optical components affects the performance of each component, the final integrated devices, and leads towards realization of biomimetically inspired imaging systems.

Uncertainties and applications of satellite-derived coastal water quality products

NASA Astrophysics Data System (ADS)

Zheng, Guangming; DiGiacomo, Paul M.

2017-12-01

Recent and forthcoming launches of a plethora of ocean color radiometry sensors, coupled with increasingly adopted free and open data policies are expected to boost usage of satellite ocean color data and drive the demand to use these data in a quantitative and routine manner. Here we review factors that introduce uncertainties to various satellite-derived water quality products and recommend approaches to minimize the uncertainty of a specific product. We show that the regression relationships between remote-sensing reflectance and water turbidity (in terms of nephelometric units) established for different regions tend to converge and therefore it is plausible to develop a global satellite water turbidity product derived using a single algorithm. In contrast, solutions to derive suspended particulate matter concentration are much less generalizable; in one case it might be more accurate to estimate this parameter based on satellite-derived particulate backscattering coefficient, whereas in another the nonagal particulate absorption coefficient might be a better proxy. Regarding satellite-derived chlorophyll concentration, known to be subject to large uncertainties in coastal waters, studies summarized here clearly indicate that the accuracy of classical reflectance band-ratio algorithms depends largely on the contribution of phytoplankton to total light absorption coefficient as well as the degree of correlation between phytoplankton and the dominant nonalgal contributions. Our review also indicates that currently available satellite-derived water quality products are restricted to optically significant materials, whereas many users are interested in toxins, nutrients, pollutants, and pathogens. Presently, proxies or indicators for these constituents are inconsistently (and often incorrectly) developed and applied. Progress in this general direction will remain slow unless, (i) optical oceanographers and environmental scientists start collaborating more closely and make optical and environmental measurements in parallel, (ii) more efforts are devoted to identifying optical, ecological, and environmental forerunners of autochthonous water quality issues (e.g., onsite growth of pathogens), and, (iii) environmental processes associated with the source, transport, and transformation of allochthonous issues (e.g., transport of nutrients) are better understood. Accompanying these challenges, the need still exists to conduct fundamental research in satellite ocean color radiometry, including development of more robust atmospheric correction methods as well as inverse models for coastal regions where optical properties of both aerosols and hydrosols are complex.

Integrated optics technology study

NASA Technical Reports Server (NTRS)

Chen, B.

1982-01-01

The materials and processes available for the fabrication of single mode integrated electrooptical components are described. Issues included in the study are: (1) host material and orientation, (2) waveguide formation, (3) optical loss mechanisms, (4) wavelength selection, (5) polarization effects and control, (6) laser to integrated optics coupling,(7) fiber optic waveguides to integrated optics coupling, (8) souces, (9) detectors. The best materials, technology and processes for fabrication of integrated optical components for communications and fiber gyro applications are recommended.

Multiple wavelength interferometry for distance measurements of moving objects with nanometer uncertainty

NASA Astrophysics Data System (ADS)

Kuschmierz, R.; Czarske, J.; Fischer, A.

2014-08-01

Optical measurement techniques offer great opportunities in diverse applications, such as lathe monitoring and microfluidics. Doppler-based interferometric techniques enable simultaneous measurement of the lateral velocity and axial distance of a moving object. However, there is a complementarity between the unambiguous axial measurement range and the uncertainty of the distance. Therefore, we present an extended sensor setup, which provides an unambiguous axial measurement range of 1 mm while achieving uncertainties below 100 nm. Measurements at a calibration system are performed. When using a pinhole for emulating a single scattering particle, the tumbling motion of the rotating object is resolved with a distance uncertainty of 50 nm. For measurements at the rough surface, the distance uncertainty amounts to 280 nm due to a lower signal-to-noise ratio. Both experimental results are close to the respective Cramér-Rao bound, which is derived analytically for both surface and single particle measurements.

A Review On Accuracy and Uncertainty of Spatial Data and Analyses with special reference to Urban and Hydrological Modelling

NASA Astrophysics Data System (ADS)

Devendran, A. A.; Lakshmanan, G.

2014-11-01

Data quality for GIS processing and analysis is becoming an increased concern due to the accelerated application of GIS technology for problem solving and decision making roles. Uncertainty in the geographic representation of the real world arises as these representations are incomplete. Identification of the sources of these uncertainties and the ways in which they operate in GIS based representations become crucial in any spatial data representation and geospatial analysis applied to any field of application. This paper reviews the articles on the various components of spatial data quality and various uncertainties inherent in them and special focus is paid to two fields of application such as Urban Simulation and Hydrological Modelling. Urban growth is a complicated process involving the spatio-temporal changes of all socio-economic and physical components at different scales. Cellular Automata (CA) model is one of the simulation models, which randomly selects potential cells for urbanisation and the transition rules evaluate the properties of the cell and its neighbour. Uncertainty arising from CA modelling is assessed mainly using sensitivity analysis including Monte Carlo simulation method. Likewise, the importance of hydrological uncertainty analysis has been emphasized in recent years and there is an urgent need to incorporate uncertainty estimation into water resources assessment procedures. The Soil and Water Assessment Tool (SWAT) is a continuous time watershed model to evaluate various impacts of land use management and climate on hydrology and water quality. Hydrological model uncertainties using SWAT model are dealt primarily by Generalized Likelihood Uncertainty Estimation (GLUE) method.

Precision pointing compensation for DSN antennas with optical distance measuring sensors

NASA Technical Reports Server (NTRS)

Scheid, R. E.

1989-01-01

The pointing control loops of Deep Space Network (DSN) antennas do not account for unmodeled deflections of the primary and secondary reflectors. As a result, structural distortions due to unpredictable environmental loads can result in uncompensated boresight shifts which degrade pointing accuracy. The design proposed here can provide real-time bias commands to the pointing control system to compensate for environmental effects on pointing performance. The bias commands can be computed in real time from optically measured deflections at a number of points on the primary and secondary reflectors. Computer simulations with a reduced-order finite-element model of a DSN antenna validate the concept and lead to a proposed design by which a ten-to-one reduction in pointing uncertainty can be achieved under nominal uncertainty conditions.

Aerosol Absorption in the Atmosphere: Perspectives from Global Model, Ground-Based Measurements, and Field Observations

NASA Technical Reports Server (NTRS)

Chin, Mian; Dubovik, Oleg; Holben, Brent; Torres, Omar; Anderson, Tad; Quinn, Patricia; Ginoux, Paul

2004-01-01

Aerosol absorption in the atmosphere poses a major uncertainty in assessing the aerosol climate effects. This uncertainty arises from the poorly quantified aerosol sources, especially black carbon emissions, and our limited knowledge of aerosol mixing state and optical properties. Here we use a global model GOCART to simulate atmospheric aerosols, including sulfate, black carbon, organic carbon, dust, and sea salt. We compare the model calculated total aerosol optical thickness, extinction, and absorption with those quantities from the ground-based sun photometer measurements from AERONET, satellite retrievals from the TOMS instrument, and field observations from ACE-Asia. We will examine the most sensitive factors in determining the aerosol absorption. and the consequences of assessing the aerosol radiative forcing and atmospheric heating associated with those factors.

Aerosol Absorption in the Atmosphere: Perspectives from Global Model, Ground-Based Measurements, and Field Observations

NASA Technical Reports Server (NTRS)

Chin, Mian; Dubovik, Oleg; Holben, Brent; Anderson, Tad; Quinn, Patricia; Duncan, Bryan; Ginoux, Paul

2003-01-01

Aerosol absorption in the atmosphere poses a major uncertainty in assessing the aerosol climate effects. This uncertainty arises from the poorly quantified aerosol sources, especially black carbon emissions, and our limited knowledge of aerosol mixing state and optical properties. Here we use a global model GOCART to simulate atmospheric aerosols, including sulfate, black carbon, organic carbon, dust, and sea salt. We compare the model calculated total aerosol optical thickness, extinction, and absorption with those quantities from the ground-based sun photometer measurements from AERONET at several different wavelengths and the field observations from ACE-Asia. We will examine what are the most sensitive factors in determining the aerosol absorption, and the consequences of assessing the aerosol radiative forcing and atmospheric heating associated with those factors.

Aerosol Absorption in the Atmosphere: Perspectives from Global Model, Ground-Based Measurements, and Field Observations

NASA Technical Reports Server (NTRS)

Chin, Main; Dubovik, Oleg; Holben, Brent; Anderson, Tad; Quinn, Patricia; Duncan, Bryan; Ginoux, Paul

2004-01-01

Aerosol absorption in the atmosphere poses a major uncertainty in assessing the aerosol climate effects. This uncertainty arises from the poorly quantified aerosol sources, especially black carbon emissions, and our limited knowledge of aerosol mixing state and optical properties. Here we use a global model GOCART to simulate atmospheric aerosols, including sulfate, black carbon, organic carbon, dust, and sea salt. We compare the model calculated total aerosol optical thickness, extinction, and absorption with those quantities from the ground-based sun photometer measurements from AERONET at several different wavelengths and the field observations from ACE-Asia. We will examine the most sensitive factors in determining the aerosol absorption, and the consequences of assessing the aerosol radiative forcing and atmospheric heating associated with those factors.

Tests and comparisons of gravity models.

NASA Technical Reports Server (NTRS)

Marsh, J. G.; Douglas, B. C.

1971-01-01

Optical observations of the GEOS satellites were used to obtain orbital solutions with different sets of geopotential coefficients. The solutions were compared before and after modification to high order terms (necessary because of resonance) and were then analyzed by comparing subsequent observations with predicted trajectories. The most important source of error in orbit determination and prediction for the GEOS satellites is the effect of resonance found in most published sets of geopotential coefficients. Modifications to the sets yield greatly improved orbits in most cases. The results of these comparisons suggest that with the best optical tracking systems and gravity models, satellite position error due to gravity model uncertainty can reach 50-100 m during a heavily observed 5-6 day orbital arc. If resonant coefficients are estimated, the uncertainty is reduced considerably.

Satellite lidar and radar: Key components of the future climate observing system

NASA Astrophysics Data System (ADS)

Winker, D. M.

2017-12-01

Cloud feedbacks represent the dominant source of uncertainties in estimates of climate sensitivity and aerosols represent the largest source of uncertainty in climate forcing. Both observation of long-term changes and observational constraints on the processes responsible for those changes are necessary. The existing 30-year record of passive satellite observations has not yet provided constraints to significantly reduce these uncertainties, though. We now have more than a decade of experience with active sensors flying in the A-Train. These new observations have demonstrated the strengths of active sensors and the benefits of continued and more advanced active sensors. This talk will discuss the multiple roles for active sensors as an essential component of a global climate observing system.

Observability considerations for multi-sensor and product fusion: Bias, information content, and validation (Invited)

NASA Astrophysics Data System (ADS)

Reid, J. S.; Zhang, J.; Hyer, E. J.; Campbell, J. R.; Christopher, S. A.; Ferrare, R. A.; Leptoukh, G. G.; Stackhouse, P. W.

2009-12-01

With the successful development of many aerosol products from the NASA A-train as well as new operational geostationary and polar orbiting sensors, the scientific community now has a host of new parameters to use in their analyses. The variety and quality of products has reached a point where the community has moved from basic observation-based science to sophisticated multi-component research that addresses the complex atmospheric environment. In order for these satellite data contribute to the science their uncertainty levels must move from semi-quantitative to quantitative. Initial attempts to quantify uncertainties have led to some recent debate in the community as to the efficacy of aerosol products from current and future NASA satellite sensors. In an effort to understand the state of satellite product fidelity, the Naval Research Laboratory and a newly reformed Global Energy and Water Cycle Experiment (GEWEX) aerosol panel have both initiated assessments of the nature of aerosol remote sensing uncertainty and bias. In this talk we go over areas of specific concern based on the authors’ experiences with the data, emphasizing the multi-sensor problem. We first enumerate potential biases, including retrieval, sampling/contextual, and cognitive bias. We show examples of how these biases can subsequently lead to the pitfalls of correlated/compensating errors, tautology, and confounding. The nature of bias is closely related to the information content of the sensor signal and its subsequent application to the derived aerosol quantity of interest (e.g., optical depth, flux, index of refraction, etc.). Consequently, purpose-specific validation methods must be employed, especially when generating multi-sensor products. Indeed, cloud and lower boundary condition biases in particular complicate the more typical methods of regressional bias elimination and histogram matching. We close with a discussion of sequestration of uncertainty in multi-sensor applications of these products in both pair-wise and fused fashions.

Transmitter And Receiver Design For Microwave Fiber Optic Links

NASA Astrophysics Data System (ADS)

Blauvelt, H.; Yen, H.

1984-11-01

Optical fibers are an attractive media for transmitting microwave signals due to their low attenuation, light weight, immunity from electromagnetic interference and large bandwidth capabilities. In this paper, transmitter and receiver components for microwave fiber optic links are reviewed. Current limitations to link signal to noise imposed by the performance of these components are analyzed and promising trends in component development are discussed.

Automatic quadrature control and measuring system. [using optical coupling circuitry

NASA Technical Reports Server (NTRS)

Hamlet, J. F. (Inventor)

1974-01-01

A quadrature component cancellation and measuring system comprising a detection system for detecting the quadrature component from a primary signal, including reference circuitry to define the phase of the quadrature component for detection is described. A Raysistor optical coupling control device connects an output from the detection system to a circuit driven by a signal based upon the primary signal. Combining circuitry connects the primary signal and the circuit controlled by the Raysistor device to subtract quadrature components. A known current through the optically sensitive element produces a signal defining the magnitude of the quadrature component.

Remote sensing of atmospheric optical depth using a smartphone sun photometer.

PubMed

Cao, Tingting; Thompson, Jonathan E

2014-01-01

In recent years, smart phones have been explored for making a variety of mobile measurements. Smart phones feature many advanced sensors such as cameras, GPS capability, and accelerometers within a handheld device that is portable, inexpensive, and consistently located with an end user. In this work, a smartphone was used as a sun photometer for the remote sensing of atmospheric optical depth. The top-of-the-atmosphere (TOA) irradiance was estimated through the construction of Langley plots on days when the sky was cloudless and clear. Changes in optical depth were monitored on a different day when clouds intermittently blocked the sun. The device demonstrated a measurement precision of 1.2% relative standard deviation for replicate photograph measurements (38 trials, 134 datum). However, when the accuracy of the method was assessed through using optical filters of known transmittance, a more substantial uncertainty was apparent in the data. Roughly 95% of replicate smart phone measured transmittances are expected to lie within ±11.6% of the true transmittance value. This uncertainty in transmission corresponds to an optical depth of approx. ±0.12-0.13 suggesting the smartphone sun photometer would be useful only in polluted areas that experience significant optical depths. The device can be used as a tool in the classroom to present how aerosols and gases effect atmospheric transmission. If improvements in measurement precision can be achieved, future work may allow monitoring networks to be developed in which citizen scientists submit acquired data from a variety of locations.

Holographic data storage crystals for LDEF (A0044)

NASA Technical Reports Server (NTRS)

Callen, W. R.; Gaylord, T. K.

1984-01-01

Electro-optic holographic recording systems were developed. The spaceworthiness of electro-optic crystals for use in ultrahigh capacity space data storage and retrieval systems are examined. The crystals for this experiment are included with the various electro-optical components of LDEF experiment. The effects of long-duration exposure on active optical system components is investigated. The concept of data storage in an optical-phase holographic memory is illustrated.

Uncertainty representation of grey numbers and grey sets.

PubMed

Yang, Yingjie; Liu, Sifeng; John, Robert

2014-09-01

In the literature, there is a presumption that a grey set and an interval-valued fuzzy set are equivalent. This presumption ignores the existence of discrete components in a grey number. In this paper, new measurements of uncertainties of grey numbers and grey sets, consisting of both absolute and relative uncertainties, are defined to give a comprehensive representation of uncertainties in a grey number and a grey set. Some simple examples are provided to illustrate that the proposed uncertainty measurement can give an effective representation of both absolute and relative uncertainties in a grey number and a grey set. The relationships between grey sets and interval-valued fuzzy sets are also analyzed from the point of view of the proposed uncertainty representation. The analysis demonstrates that grey sets and interval-valued fuzzy sets provide different but overlapping models for uncertainty representation in sets.

Uncertainty after treatment for prostate cancer: definition, assessment, and management.

PubMed

Yu Ko, Wellam F; Degner, Lesley F

2008-10-01

Prostate cancer is the second most common type of cancer in men living in the United States and the most common type of malignancy in Canadian men, accounting for 186,320 new cases in the United States and 24,700 in Canada in 2008. Uncertainty, a component of all illness experiences, influences how men perceive the processes of treatment and adaptation. The Reconceptualized Uncertainty in Illness Theory explains the chronic nature of uncertainty in cancer survivorship by describing a shift from an emergent acute phase of uncertainty in survivors to a new level of uncertainty that is no longer acute and becomes a part of daily life. Proper assessment of certainty and uncertainty may allow nurses to maximize the effectiveness of patient-provider communication, cognitive reframing, and problem-solving interventions to reduce uncertainty after cancer treatment.

Monthly Fossil-Fuel CO2 Emissions: Uncertainty of Emissions Gridded by On Degree Latitude by One Degree Longitude (Uncertainties, V.2016)

DOE Data Explorer

Andres, J.A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Boden, T.A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2016-01-01

The monthly, gridded fossil-fuel CO2 emissions uncertainty estimates from 1950-2013 provided in this database are derived from time series of global, regional, and national fossil-fuel CO2 emissions (Boden et al. 2016). Andres et al. (2016) describes the basic methodology in estimating the uncertainty in the (gridded fossil fuel data product ). This uncertainty is gridded at the same spatial and temporal scales as the mass magnitude maps. This gridded uncertainty includes uncertainty contributions from the spatial, temporal, proxy, and magnitude components used to create the magnitude map of FFCO2 emissions. Throughout this process, when assumptions had to be made or expert judgment employed, the general tendency in most cases was toward overestimating or increasing the magnitude of uncertainty.

Parasitic light scattered by complex optical coatings: modelization and metrology

NASA Astrophysics Data System (ADS)

Zerrad, Myriam; Lequime, Michel; Liukaityte, Simona; Amra, Claude

2017-12-01

Optical components realized for space applications have to be mastered in term of parasitic light. This paper present the last improvements performed at the Institute Fresnel to predict and measure scattering losses of optical components with a special care to complex optical coatings. Agreement between numerical models and metrology is now excellent. Some examples will be presented.

Dose evaluation of an NIPAM polymer gel dosimeter using gamma index

NASA Astrophysics Data System (ADS)

Chang, Yuan-Jen; Lin, Jing-Quan; Hsieh, Bor-Tsung; Yao, Chun-Hsu; Chen, Chin-Hsing

2014-11-01

An N-isopropylacrylamide (NIPAM) polymer gel dosimeter has great potential in clinical applications. However, its three-dimensional dose distribution must be assessed. In this work, a quantitative evaluation of dose distributions was performed to evaluate the NIPAM polymer gel dosimeter using gamma analysis. A cylindrical acrylic phantom filled with NIPAM gel measuring 10 cm (diameter) by 10 cm (height) by 3 mm (thickness) was irradiated by a 4×4 cm2 square light field. The irradiated gel phantom was scanned using an optical computed tomography (optical CT) scanner (OCTOPUS™, MGS Research, Inc., Madison, CT, USA) at 1 mm resolution. The projection data were transferred to an image reconstruction program, which was written using MATLAB (The MathWorks, Natick, MA, USA). The program reconstructed the image of the optical density distribution using the algorithm of a filter back-projection. Three batches of replicated gel phantoms were independently measured. The average uncertainty of the measurements was less than 1%. The gel was found to have a high degree of spatial uniformity throughout the dosimeter and good temporal stability. A comparison of the line profiles of the treatment planning system and of the data measured by optical CT showed that the dose was overestimated in the penumbra region because of two factors. The first is light scattering due to changes in the refractive index at the edge of the irradiated field. The second is the edge enhancement caused by free radical diffusion. However, the effect of edge enhancement on the NIPAM gel dosimeter is not as significant as that on the BANG gel dosimeter. Moreover, the dose uncertainty is affected by the inaccuracy of the gel container positioning process. To reduce the uncertainty of 3D dose distribution, improvements in the gel container holder must be developed.

Innovative hybrid optics: combining the thermal stability of glass with low manufacturing cost of polymers

NASA Astrophysics Data System (ADS)

Doushkina, Valentina

2010-08-01

Innovative hybrid glass-polymer optical solutions on a component, module, or system level offer thermal stability of glass with low manufacturing cost of polymers reducing component weight, enhancing the safety and appeal of the products. Narrow choice of polymer materials is compensated by utilizing sophisticated optical surfaces such as refractive, reflective, and diffractive substrates with spherical, aspherical, cylindrical, and freeform prescriptions. Current advancements in polymer technology and injection molding capabilities placed polymer optics in the heart of many high tech devices and applications including Automotive Industry, Defense & Aerospace; Medical/Bio Science; Projection Displays, Sensors, Information Technology, Commercial and Industrial. This paper is about integration of polymer and glass optics for enhanced optical performance with reduced number of components, thermal stability, and low manufacturing cost. The listed advantages are not achievable when polymers or glass optics are used as stand-alone. The author demonstrates that integration of polymer and glass on component or optical system level on one hand offers high resolution and diffraction limited image quality, similar to the glass optics with stable refractive index and stable thermal performance when design is athermalized within the temperature range. On the other hand, the integrated hybrid solution significantly reduces cost, weight, and complexity, just like the polymer optics. The author will describe the design and analyzes process of combining glass and polymer optics for variety of challenging applications such as fast optics with low F/#, wide field of view lenses or systems, free form optics, etc.

State-of-the-art survey of multimode fiber optic wavelength division multiplexing

NASA Astrophysics Data System (ADS)

Spencer, J. L.

1983-05-01

Optical wavelength division multiplexing (WDM) systems, with signals transmitted on different wavelengths through a single fiber, can have increased information capacity and fault isolation properties over single wavelength optical systems. This paper describes a typical WDM system. Also, a state-of-the-art survey of optical multimode components which could be used to implement the system is made. The components to be surveyed are sources, multiplexers, and detectors. Emphasis is given to the demultiplexer techniques which are the major development components in the WDM system.

10 CFR 50.48 - Fire protection.

Code of Federal Regulations, 2011 CFR

2011-01-01

... suppression systems; and (iii) The means to limit fire damage to structures, systems, or components important...) Standard 805, “Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating... pressurized-water reactors (PWRs) is not permitted. (iv) Uncertainty analysis. An uncertainty analysis...

10 CFR 50.48 - Fire protection.

Code of Federal Regulations, 2010 CFR

2010-01-01

... suppression systems; and (iii) The means to limit fire damage to structures, systems, or components important...) Standard 805, “Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating... pressurized-water reactors (PWRs) is not permitted. (iv) Uncertainty analysis. An uncertainty analysis...

Biochemical component identification by plasmonic improved whispering gallery mode optical resonance based sensor

NASA Astrophysics Data System (ADS)

Saetchnikov, Vladimir A.; Tcherniavskaia, Elina A.; Saetchnikov, Anton V.; Schweiger, Gustav; Ostendorf, Andreas

2014-05-01

Experimental data on detection and identification of variety of biochemical agents, such as proteins, microelements, antibiotic of different generation etc. in both single and multi component solutions under varied in wide range concentration analyzed on the light scattering parameters of whispering gallery mode optical resonance based sensor are represented. Multiplexing on parameters and components has been realized using developed fluidic sensor cell with fixed in adhesive layer dielectric microspheres and data processing. Biochemical component identification has been performed by developed network analysis techniques. Developed approach is demonstrated to be applicable both for single agent and for multi component biochemical analysis. Novel technique based on optical resonance on microring structures, plasmon resonance and identification tools has been developed. To improve a sensitivity of microring structures microspheres fixed by adhesive had been treated previously by gold nanoparticle solution. Another technique used thin film gold layers deposited on the substrate below adhesive. Both biomolecule and nanoparticle injections caused considerable changes of optical resonance spectra. Plasmonic gold layers under optimized thickness also improve parameters of optical resonance spectra. Biochemical component identification has been also performed by developed network analysis techniques both for single and for multi component solution. So advantages of plasmon enhancing optical microcavity resonance with multiparameter identification tools is used for development of a new platform for ultra sensitive label-free biomedical sensor.

Use of meteorological information in the risk analysis of a mixed wind farm and solar

NASA Astrophysics Data System (ADS)

Mengelkamp, H.-T.; Bendel, D.

2010-09-01

Use of meteorological information in the risk analysis of a mixed wind farm and solar power plant portfolio H.-T. Mengelkamp*,** , D. Bendel** *GKSS Research Center Geesthacht GmbH **anemos Gesellschaft für Umweltmeteorologie mbH The renewable energy industry has rapidly developed during the last two decades and so have the needs for high quality comprehensive meteorological services. It is, however, only recently that international financial institutions bundle wind farms and solar power plants and offer shares in these aggregate portfolios. The monetary value of a mixed wind farm and solar power plant portfolio is determined by legal and technical aspects, the expected annual energy production of each wind farm and solar power plant and the associated uncertainty of the energy yield estimation or the investment risk. Building an aggregate portfolio will reduce the overall uncertainty through diversification in contrast to the single wind farm/solar power plant energy yield uncertainty. This is similar to equity funds based on a variety of companies or products. Meteorological aspects contribute to the diversification in various ways. There is the uncertainty in the estimation of the expected long-term mean energy production of the wind and solar power plants. Different components of uncertainty have to be considered depending on whether the power plant is already in operation or in the planning phase. The uncertainty related to a wind farm in the planning phase comprises the methodology of the wind potential estimation and the uncertainty of the site specific wind turbine power curve as well as the uncertainty of the wind farm effect calculation. The uncertainty related to a solar power plant in the pre-operational phase comprises the uncertainty of the radiation data base and that of the performance curve. The long-term mean annual energy yield of operational wind farms and solar power plants is estimated on the basis of the actual energy production and it's relation to a climatologically stable long-term reference period. These components of uncertainty are of technical nature and based on subjective estimations rather than on a statistically sound data analysis. And then there is the temporal and spatial variability of the wind speed and radiation. Their influence on the overall risk is determined by the regional distribution of the power plants. These uncertainty components are calculated on the basis of wind speed observations and simulations and satellite derived radiation data. The respective volatility (temporal variability) is calculated from the site specific time series and the influence on the portfolio through regional correlation. For an exemplary portfolio comprising fourteen wind farms and eight solar power plants the annual mean energy production to be expected is calculated, the different components of uncertainty are estimated for each single wind farm and solar power plant and for the portfolio as a whole. The reduction in uncertainty (or risk) through bundling the wind farms and the solar power plants (the portfolio effect) is calculated by Markowitz' Modern Portfolio Theory. This theory is applied separately for the wind farm and the solar power plant bundle and for the combination of both. The combination of wind and photovoltaic assets clearly shows potential for a risk reduction. Even assets with a comparably low expected return can lead to a significant risk reduction depending on their individual characteristics.

Measurement of picometre non-linearity in an optical grating encoder using x-ray interferometry

NASA Astrophysics Data System (ADS)

Yacoot, Andrew; Cross, Nigel

2003-01-01

X-ray interferometry has been used to characterize the non-linearity in an optical encoder displacement measuring system. Traceable measurements of the non-linearity have been made and an estimation of the uncertainty associated with the measurements is given. Cyclic errors with a magnitude of up to 50 pm and periodicity of the encoder system (128 nm) have been recorded.

76 FR 66750 - Certain Projectors With Controlled-Angle Optical Retarders, Components Thereof, and Products...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-27

... INTERNATIONAL TRADE COMMISSION [DN 2849] Certain Projectors With Controlled-Angle Optical... Re Certain Projectors with Controlled-Angle Optical Retarders, Components Thereof, And Products... complaint. FOR FURTHER INFORMATION CONTACT: James R. Holbein, Secretary to the Commission, U.S...

Formation of C3 and C2 in Cometary Comae

NASA Astrophysics Data System (ADS)

Hölscher, Alexander

2015-03-01

Comets are remnants from the Solar System formation. They reside at large distances from the Sun and are believed to store deep freeze imprints of the chemical and physical conditions at the time the Solar System formed. The main ice component of a comet is H2O followed by CO and CO2 with additional small amounts of molecules with varying complexity. Comets also contain large amounts of dust. If a comet approaches the Sun the ices begin to sublimate giving rise to the cometary coma. The molecules producing the coma can be observed in the infrared, the radio wavelength range and at optical wavelengths. To constrain the formation of the Solar System, models require knowledge of the composition for a statistically significant number of comets. This favors optical observations of e.g. C3 (tricarbon) and C2 (dicarbon) since these species allow observations even of relatively faint comets and do not require space missions (infrared observations). However, one has to link these observed photodissociation product species (daughter species) to the molecules that originally sublimated from the comet nucleus surface, i.e. the so-called parent molecules, as e.g. C2H2 (acetylene) for C2. However, for C3 no parent molecules have been identified so far. This thesis investigates the formation of C3 and C2 radicals in cometary comae due to photodissociation of observed and in the literature proposed hydrocarbon parent molecules. For this purpose a one-dimensional multi-fluid coma chemistry model has been improved and applied. This work added new photo reactions to the model, updated the hydrocarbon photo rate coefficients and quantified their uncertainty. A sensitivity analysis has been carried out to determine the reactions whose uncertainty most affect the model output uncertainty. Special attention should be paid to these so-called key reactions in future laboratory experiments and quantum chemical computations to reduce the model output uncertainty more effectively. This will allow to better constrain which parent molecules are responsible for the observational C3 and C2 column densities. Based on observations of the four sample comets C/2001 Q4 (NEAT), C/2002 T7 (LINEAR), 9P (Tempel 1) and C/1995 O1 (Hale-Bopp), this work investigates which combination of the following proposed parent molecules C4H2 (diacetylene), CH2C2H2 (allene), CH3C2H (propyne), C2H4 (ethene) and observed parent molecules C2H2 and HC3N (cyanoacetylene) can best reproduce the observational C3 and C2 column densities in cometary comae, taking into account the uncertainties in photodissociation rate coefficients. It was found that the investigated photodissociation rate coefficients have large uncertainties and also a significant effect on the C3 and C2 model column densities. The responsible key reactions were determined with the sensitivity analysis. The important result of this thesis is that one can reasonably well reproduce the observations of comets with the improved model at rh = 1.00 AU (NEAT) and rh = 3.78 AU (Hale-Bopp), within the photodissociation uncertainties using realistic parent molecule production rate ratios and by various combinations of the investigated parent molecules. To confirm the agreement (NEAT, Hale-Bopp) and to clearify remaining discrepancies (LINEAR, Tempel 1) between model and observations requires additional observations of parent and daughter molecules in the coma of comets as well as in situ measurements of cometary ices (Rosetta).zeige weniger

Influence of Population Variation of Physiological Parameters in Computational Models of Space Physiology

NASA Technical Reports Server (NTRS)

Myers, J. G.; Feola, A.; Werner, C.; Nelson, E. S.; Raykin, J.; Samuels, B.; Ethier, C. R.

2016-01-01

The earliest manifestations of Visual Impairment and Intracranial Pressure (VIIP) syndrome become evident after months of spaceflight and include a variety of ophthalmic changes, including posterior globe flattening and distension of the optic nerve sheath. Prevailing evidence links the occurrence of VIIP to the cephalic fluid shift induced by microgravity and the subsequent pressure changes around the optic nerve and eye. Deducing the etiology of VIIP is challenging due to the wide range of physiological parameters that may be influenced by spaceflight and are required to address a realistic spectrum of physiological responses. Here, we report on the application of an efficient approach to interrogating physiological parameter space through computational modeling. Specifically, we assess the influence of uncertainty in input parameters for two models of VIIP syndrome: a lumped-parameter model (LPM) of the cardiovascular and central nervous systems, and a finite-element model (FEM) of the posterior eye, optic nerve head (ONH) and optic nerve sheath. Methods: To investigate the parameter space in each model, we employed Latin hypercube sampling partial rank correlation coefficient (LHSPRCC) strategies. LHS techniques outperform Monte Carlo approaches by enforcing efficient sampling across the entire range of all parameters. The PRCC method estimates the sensitivity of model outputs to these parameters while adjusting for the linear effects of all other inputs. The LPM analysis addressed uncertainties in 42 physiological parameters, such as initial compartmental volume and nominal compartment percentage of total cardiac output in the supine state, while the FEM evaluated the effects on biomechanical strain from uncertainties in 23 material and pressure parameters for the ocular anatomy. Results and Conclusion: The LPM analysis identified several key factors including high sensitivity to the initial fluid distribution. The FEM study found that intraocular pressure and intracranial pressure had dominant impact on the peak strains in the ONH and retro-laminar optic nerve, respectively; optic nerve and lamina cribrosa stiffness were also important. This investigation illustrates the ability of LHSPRCC to identify the most influential physiological parameters, which must therefore be well-characterized to produce the most accurate numerical results.

Optoelectronic system for the determination of blood volume in pneumatic heart assist devices.

PubMed

Konieczny, Grzegorz; Pustelny, Tadeusz; Setkiewicz, Maciej; Gawlikowski, Maciej

2015-12-10

The following article describes the concept of optical measurement of blood volume in ventricular assist devices (VAD's) of the pulsatile type. The paper presents the current state of art in blood volume measurements of such devices and introduces a newly developed solution in the optic domain. The objective of the research is to overcome the disadvantages of the previously developed acoustic method-the requirement of additional sensor chamber. The idea of a compact measurement system has been introduced, followed by laboratory measurements. Static tests of the system have been presented, followed by dynamic measurements on a physical model of the human ventricular system. The results involving the measurements of blood chamber volume acquired by means of an optical system have been compared with the results acquired by means of the Transonic T410 ultrasound flow rate sensor (11PLX transducer, uncertainty ±5 %). Preliminary dynamic measurements conducted on the physical model of the human cardiovascular system show that the proposed optical measurement system may be used to measure the transient blood chamber volumes of pulsatile VAD's with the uncertainties (standard mean deviation) lower than 10 %. The results show that the noninvasive measurements of the temporary blood chamber volume in the POLVAD prosthesis with the use of the developed optical system allows us to carry out accurate static and dynamic measurements.

Evaluation of Uncertainty in Constituent Input Parameters for Modeling the Fate of IMX 101 Components

DTIC Science & Technology

2017-05-01

ER D C/ EL T R- 17 -7 Environmental Security Technology Certification Program (ESTCP) Evaluation of Uncertainty in Constituent Input...Environmental Security Technology Certification Program (ESTCP) ERDC/EL TR-17-7 May 2017 Evaluation of Uncertainty in Constituent Input Parameters...Environmental Evaluation and Characterization Sys- tem (TREECS™) was applied to a groundwater site and a surface water site to evaluate the sensitivity

Soft optics in intelligent optical networks

NASA Astrophysics Data System (ADS)

Shue, Chikong; Cao, Yang

2001-10-01

In addition to the recent advances in Hard-optics that pushes the optical transmission speed, distance, wave density and optical switching capacity, Soft-optics provides the necessary intelligence and control software that reduces operational costs, increase efficiency, and enhances revenue generating services by automating optimal optical circuit placement and restoration, and enabling value-added new services like Optical VPN. This paper describes the advances in 1) Overall Hard-optics and Soft-optics 2) Layered hierarchy of Soft-optics 3) Component of Soft-optics, including hard-optics drivers, Management Soft-optics, Routing Soft-optics and System Soft-optics 4) Key component of Routing and System Soft-optics, namely optical routing and signaling (including UNI/NNI and GMPLS signaling). In summary, the soft-optics on a new generation of OXC's enables Intelligent Optical Networks to provide just-in-time service delivery and fast restoration, and real-time capacity management that eliminates stranded bandwidth. It reduces operational costs and provides new revenue opportunities.

Robustness analysis of bogie suspension components Pareto optimised values

NASA Astrophysics Data System (ADS)

Mousavi Bideleh, Seyed Milad

2017-08-01

Bogie suspension system of high speed trains can significantly affect vehicle performance. Multiobjective optimisation problems are often formulated and solved to find the Pareto optimised values of the suspension components and improve cost efficiency in railway operations from different perspectives. Uncertainties in the design parameters of suspension system can negatively influence the dynamics behaviour of railway vehicles. In this regard, robustness analysis of a bogie dynamics response with respect to uncertainties in the suspension design parameters is considered. A one-car railway vehicle model with 50 degrees of freedom and wear/comfort Pareto optimised values of bogie suspension components is chosen for the analysis. Longitudinal and lateral primary stiffnesses, longitudinal and vertical secondary stiffnesses, as well as yaw damping are considered as five design parameters. The effects of parameter uncertainties on wear, ride comfort, track shift force, stability, and risk of derailment are studied by varying the design parameters around their respective Pareto optimised values according to a lognormal distribution with different coefficient of variations (COVs). The robustness analysis is carried out based on the maximum entropy concept. The multiplicative dimensional reduction method is utilised to simplify the calculation of fractional moments and improve the computational efficiency. The results showed that the dynamics response of the vehicle with wear/comfort Pareto optimised values of bogie suspension is robust against uncertainties in the design parameters and the probability of failure is small for parameter uncertainties with COV up to 0.1.

Digital polarization holography advancing geometrical phase optics.

PubMed

De Sio, Luciano; Roberts, David E; Liao, Zhi; Nersisyan, Sarik; Uskova, Olena; Wickboldt, Lloyd; Tabiryan, Nelson; Steeves, Diane M; Kimball, Brian R

2016-08-08

Geometrical phase or the fourth generation (4G) optics enables realization of optical components (lenses, prisms, gratings, spiral phase plates, etc.) by patterning the optical axis orientation in the plane of thin anisotropic films. Such components exhibit near 100% diffraction efficiency over a broadband of wavelengths. The films are obtained by coating liquid crystalline (LC) materials over substrates with patterned alignment conditions. Photo-anisotropic materials are used for producing desired alignment conditions at the substrate surface. We present and discuss here an opportunity of producing the widest variety of "free-form" 4G optical components with arbitrary spatial patterns of the optical anisotropy axis orientation with the aid of a digital spatial light polarization converter (DSLPC). The DSLPC is based on a reflective, high resolution spatial light modulator (SLM) combined with an "ad hoc" optical setup. The most attractive feature of the use of a DSLPC for photoalignment of nanometer thin photo-anisotropic coatings is that the orientation of the alignment layer, and therefore of the fabricated LC or LC polymer (LCP) components can be specified on a pixel-by-pixel basis with high spatial resolution. By varying the optical magnification or de-magnification the spatial resolution of the photoaligned layer can be adjusted to an optimum for each application. With a simple "click" it is possible to record different optical components as well as arbitrary patterns ranging from lenses to invisible labels and other transparent labels that reveal different images depending on the side from which they are viewed.

A Simple Model Framework to Explore the Deeply Uncertain, Local Sea Level Response to Climate Change. A Case Study on New Orleans, Louisiana

NASA Astrophysics Data System (ADS)

Bakker, Alexander; Louchard, Domitille; Keller, Klaus

2016-04-01

Sea-level rise threatens many coastal areas around the world. The integrated assessment of potential adaptation and mitigation strategies requires a sound understanding of the upper tails and the major drivers of the uncertainties. Global warming causes sea-level to rise, primarily due to thermal expansion of the oceans and mass loss of the major ice sheets, smaller ice caps and glaciers. These components show distinctly different responses to temperature changes with respect to response time, threshold behavior, and local fingerprints. Projections of these different components are deeply uncertain. Projected uncertainty ranges strongly depend on (necessary) pragmatic choices and assumptions; e.g. on the applied climate scenarios, which processes to include and how to parameterize them, and on error structure of the observations. Competing assumptions are very hard to objectively weigh. Hence, uncertainties of sea-level response are hard to grasp in a single distribution function. The deep uncertainty can be better understood by making clear the key assumptions. Here we demonstrate this approach using a relatively simple model framework. We present a mechanistically motivated, but simple model framework that is intended to efficiently explore the deeply uncertain sea-level response to anthropogenic climate change. The model consists of 'building blocks' that represent the major components of sea-level response and its uncertainties, including threshold behavior. The framework's simplicity enables the simulation of large ensembles allowing for an efficient exploration of parameter uncertainty and for the simulation of multiple combined adaptation and mitigation strategies. The model framework can skilfully reproduce earlier major sea level assessments, but due to the modular setup it can also be easily utilized to explore high-end scenarios and the effect of competing assumptions and parameterizations.

3D-printed optical active components

NASA Astrophysics Data System (ADS)

Suresh Nair, S.; Nuding, J.; Heinrich, A.

2018-02-01

Additive Manufacturing (AM) has the potential to become a powerful tool in the realization of complex optical components. The primary advantage that meets the eye, is that fabrication of geometrically complicated optical structures is made easier in AM as compared to the conventional fabrication methods (using molds for instance). But this is not the only degree of freedom that AM has to offer. With the multitude of materials suitable for AM in the market, it is possible to introduce functionality into the components one step before fabrication: by altering the raw material. A passive example would be to use materials with varying properties together, in a single manufacturing step, constructing samples with localized refractive indices for instance. An active approach is to blend in materials with distinct properties into the photopolymer resin and manufacturing with this composite material. Our research is currently focused in this direction, with the desired optical property to be introduced being Photoluminescence. Formation of nanocomposite mixtures to produce samples is the current approach. With this endeavor, new sensor systems can be realized, which may be used to measure the absorption spectra of biological samples. Thereby the sample compartment, the optics and the spectral light source (different quantum dots) are 3D-printed in one run. This component can be individually adapted to the biological sample with respect to wavelength, optical and mechanical properties. Here we would like to present our work on the additive manufacturing of an active optical component. Based on the stereolithography method, a monolithic optical component was 3D-printed, showing light emission at different defined wavelengths due to UV excited quantum dots inside the 3D-printed optics.

Global Coordinates and Exact Aberration Calculations Applied to Physical Optics Modeling of Complex Optical Systems

NASA Astrophysics Data System (ADS)

Lawrence, G.; Barnard, C.; Viswanathan, V.

1986-11-01

Historically, wave optics computer codes have been paraxial in nature. Folded systems could be modeled by "unfolding" the optical system. Calculation of optical aberrations is, in general, left for the analyst to do with off-line codes. While such paraxial codes were adequate for the simpler systems being studied 10 years ago, current problems such as phased arrays, ring resonators, coupled resonators, and grazing incidence optics require a major advance in analytical capability. This paper describes extension of the physical optics codes GLAD and GLAD V to include a global coordinate system and exact ray aberration calculations. The global coordinate system allows components to be positioned and rotated arbitrarily. Exact aberrations are calculated for components in aligned or misaligned configurations by using ray tracing to compute optical path differences and diffraction propagation. Optical path lengths between components and beam rotations in complex mirror systems are calculated accurately so that coherent interactions in phased arrays and coupled devices may be treated correctly.

State-of-the-art fiber optics for short distance frequency reference distribution

NASA Astrophysics Data System (ADS)

Lutes, G. F.; Primas, L. E.

1989-05-01

A number of recently developed fiber-optic components that hold the promise of unprecedented stability for passively stabilized frequency distribution links are characterized. These components include a fiber-optic transmitter, an optical isolator, and a new type of fiber-optic cable. A novel laser transmitter exhibits extremely low sensitivity to intensity and polarization changes of reflected light due to cable flexure. This virtually eliminates one of the shortcomings in previous laser transmitters. A high-isolation, low-loss optical isolator has been developed which also virtually eliminates laser sensitivity to changes in intensity and polarization of reflected light. A newly developed fiber has been tested. This fiber has a thermal coefficient of delay of less than 0.5 parts per million per deg C, nearly 20 times lower than the best coaxial hardline cable and 10 times lower than any previous fiber-optic cable. These components are highly suitable for distribution systems with short extent, such as within a Deep Space Communications Complex. Here, these new components are described and the test results presented.

State-of-the-art fiber optics for short distance frequency reference distribution

NASA Technical Reports Server (NTRS)

Lutes, G. F.; Primas, L. E.

1989-01-01

A number of recently developed fiber-optic components that hold the promise of unprecedented stability for passively stabilized frequency distribution links are characterized. These components include a fiber-optic transmitter, an optical isolator, and a new type of fiber-optic cable. A novel laser transmitter exhibits extremely low sensitivity to intensity and polarization changes of reflected light due to cable flexure. This virtually eliminates one of the shortcomings in previous laser transmitters. A high-isolation, low-loss optical isolator has been developed which also virtually eliminates laser sensitivity to changes in intensity and polarization of reflected light. A newly developed fiber has been tested. This fiber has a thermal coefficient of delay of less than 0.5 parts per million per deg C, nearly 20 times lower than the best coaxial hardline cable and 10 times lower than any previous fiber-optic cable. These components are highly suitable for distribution systems with short extent, such as within a Deep Space Communications Complex. Here, these new components are described and the test results presented.

Using a two-lens afocal compensator for thermal defocus correction of catadioptric system

NASA Astrophysics Data System (ADS)

Ivanov, S. E.; Romanova, G. E.; Bakholdin, A. V.

2017-08-01

The work associates with the catadioptric systems with two-component afocal achromatic compensator. The most catadioptric systems with afocal compensator have the power mirror part and the correctional lens part. The correctional lens part can be in parallel, in convergent beam or in both. One of the problems of such systems design is the thermal defocus by reason of the thermal aberration and the housing thermal expansion. We introduce the technique of thermal defocus compensation by choosing the optical material of the afocal compensator components. The components should be made from the optical materials with thermo-optical characteristics so after temperature changing the compensator should become non-afocal with the optical power enough to compensate the image plane thermal shift. Abbe numbers of the components should also have certain values for correction chromatic aberrations that reduces essentially the applicable optical materials quantity. The catalogues of the most vendors of optical materials in visible spectral range are studied for the purpose of finding the suitable couples for the technique. As a result, the advantages and possibilities of the plastic materials application in combination with optical glasses are shown. The examples of the optical design are given.

Virtual commissioning of automated micro-optical assembly

NASA Astrophysics Data System (ADS)

Schlette, Christian; Losch, Daniel; Haag, Sebastian; Zontar, Daniel; Roßmann, Jürgen; Brecher, Christian

2015-02-01

In this contribution, we present a novel approach to enable virtual commissioning for process developers in micro-optical assembly. Our approach aims at supporting micro-optics experts to effectively develop assisted or fully automated assembly solutions without detailed prior experience in programming while at the same time enabling them to easily implement their own libraries of expert schemes and algorithms for handling optical components. Virtual commissioning is enabled by a 3D simulation and visualization system in which the functionalities and properties of automated systems are modeled, simulated and controlled based on multi-agent systems. For process development, our approach supports event-, state- and time-based visual programming techniques for the agents and allows for their kinematic motion simulation in combination with looped-in simulation results for the optical components. First results have been achieved for simply switching the agents to command the real hardware setup after successful process implementation and validation in the virtual environment. We evaluated and adapted our system to meet the requirements set by industrial partners-- laser manufacturers as well as hardware suppliers of assembly platforms. The concept is applied to the automated assembly of optical components for optically pumped semiconductor lasers and positioning of optical components for beam-shaping

Ion beam machining error control and correction for small scale optics.

PubMed

Xie, Xuhui; Zhou, Lin; Dai, Yifan; Li, Shengyi

2011-09-20

Ion beam figuring (IBF) technology for small scale optical components is discussed. Since the small removal function can be obtained in IBF, it makes computer-controlled optical surfacing technology possible to machine precision centimeter- or millimeter-scale optical components deterministically. Using a small ion beam to machine small optical components, there are some key problems, such as small ion beam positioning on the optical surface, material removal rate, ion beam scanning pitch control on the optical surface, and so on, that must be seriously considered. The main reasons for the problems are that it is more sensitive to the above problems than a big ion beam because of its small beam diameter and lower material ratio. In this paper, we discuss these problems and their influences in machining small optical components in detail. Based on the identification-compensation principle, an iterative machining compensation method is deduced for correcting the positioning error of an ion beam with the material removal rate estimated by a selected optimal scanning pitch. Experiments on ϕ10 mm Zerodur planar and spherical samples are made, and the final surface errors are both smaller than λ/100 measured by a Zygo GPI interferometer.

Advanced optical components for next-generation photonic networks

NASA Astrophysics Data System (ADS)

Yoo, S. J. B.

2003-08-01

Future networks will require very high throughput, carrying dominantly data-centric traffic. The role of Photonic Networks employing all-optical systems will become increasingly important in providing scalable bandwidth, agile reconfigurability, and low-power consumptions in the future. In particular, the self-similar nature of data traffic indicates that packet switching and burst switching will be beneficial in the Next Generation Photonic Networks. While the natural conclusion is to pursue Photonic Packet Switching and Photonic Burst Switching systems, there are significant challenges in realizing such a system due to practical limitations in optical component technologies. Lack of a viable all-optical memory technology will continue to drive us towards exploring rapid reconfigurability in the wavelength domain. We will introduce and discuss the advanced optical component technologies behind the Photonic Packet Routing system designed and demonstrated at UC Davis. The system is capable of packet switching and burst switching, as well as circuit switching with 600 psec switching speed and scalability to 42 petabit/sec aggregated switching capacity. By utilizing a combination of rapidly tunable wavelength conversion and a uniform-loss cyclic frequency (ULCF) arrayed waveguide grating router (AWGR), the system is capable of rapidly switching the packets in wavelength, time, and space domains. The label swapping module inside the Photonic Packet Routing system containing a Mach-Zehnder wavelength converter and a narrow-band fiber Bragg-grating achieves all-optical label swapping with optical 2R (potentially 3R) regeneration while maintaining optical transparency for the data payload. By utilizing the advanced optical component technologies, the Photonic Packet Routing system successfully demonstrated error-free, cascaded, multi-hop photonic packet switching and routing with optical-label swapping. This paper will review the advanced optical component technologies and their role in the Next Generation Photonic Networks.

MERIS Retrieval of Water Quality Components in the Turbid Albemarle-Pamlico Sound Estuary, USA

EPA Science Inventory

Biological, geophysical and optical field observations carried out in the Neuse River Estuary, North Carolina, USA were used to develop a semi-empirical optical algorithm for assessing inherent optical properties associated with water quality components (WQCs). Three wavelengths ...

Process for sensing defects on a smooth cylindrical interior surface in tubing

DOEpatents

Dutton, G. Wayne

1987-11-17

The cylindrical interior surface of small diameter metal tubing is optically inspected to determine surface roughness by passing a slightly divergent light beam to illuminate the entire interior surface of the tubing. Impingement of the input light beam components on any rough spots on the interior surface generates forward and backward scattered radiation components. The forward scattered components can be measured by blocking direct and specular radiation components exiting the tubing while allowing the forward scattered radiation to travel past the blocking location. Collecting optics are employed to converge the forward scattered radiation onto a photodetector generating a signal indicative of surface roughness. In the back scattered mode, back scattered radiation exiting the tubing through the entrance opening is reflected 90.degree. by a beam splitter towards collecting optics and a photodetector. Alternatively, back scattered radiation can be transmitted through a fiber optic bundle towards the collecting optics. The input light beam can be supplied through a white light fiber optic bundle mounted coaxial with the first bundle.

Process for sensing defects on a smooth cylindrical interior surface in tubing

DOEpatents

Dutton, G.W.

1987-11-17

The cylindrical interior surface of small diameter metal tubing is optically inspected to determine surface roughness by passing a slightly divergent light beam to illuminate the entire interior surface of the tubing. Impingement of the input light beam components on any rough spots on the interior surface generates forward and backward scattered radiation components. The forward scattered components can be measured by blocking direct and specular radiation components exiting the tubing while allowing the forward scattered radiation to travel past the blocking location. Collecting optics are employed to converge the forward scattered radiation onto a photodetector generating a signal indicative of surface roughness. In the back scattered mode, back scattered radiation exiting the tubing through the entrance opening is reflected 90[degree] by a beam splitter towards collecting optics and a photodetector. Alternatively, back scattered radiation can be transmitted through a fiber optic bundle towards the collecting optics. The input light beam can be supplied through a white light fiber optic bundle mounted coaxial with the first bundle. 6 figs.

Process and apparatus for sensing defects on a smooth cylindrical surface in tubing

DOEpatents

Dutton, G.W.

1985-08-05

The cylindrical interior surface of small diameter metal tubing is optically inspected to determine surface roughness by passing a slightly divergent light beam to illuminate the entire interior surface of the tubing. Impingement of the input light beam components on any rough spots on the interior surface generates forward and backward scattered radiation components. The forward scattered components can be measured by blocking direct and specular radiation components exiting the tubing while allowing the forward scattered radiation to travel past the blocking location. Collecting optics are employed to converge the forward scattered radiation onto a photodetector generating a signal indicative of surface roughness. In the back scattered mode, back scattered radiation exiting the tubing through the entrance opening is reflected 90/sup 0/ by a beam splitter towards collecting optics and a photodetector. Alternatively, back scattered radiation can be transmitted through a fiber optic bundle towards the collecting optics. The input light beam can be supplied through a white light fiber optic bundle mounted coaxial with the first bundle.

Covariance propagation in spectral indices

DOE PAGES

Griffin, P. J.

2015-01-09

In this study, the dosimetry community has a history of using spectral indices to support neutron spectrum characterization and cross section validation efforts. An important aspect to this type of analysis is the proper consideration of the contribution of the spectrum uncertainty to the total uncertainty in calculated spectral indices (SIs). This study identifies deficiencies in the traditional treatment of the SI uncertainty, provides simple bounds to the spectral component in the SI uncertainty estimates, verifies that these estimates are reflected in actual applications, details a methodology that rigorously captures the spectral contribution to the uncertainty in the SI, andmore » provides quantified examples that demonstrate the importance of the proper treatment the spectral contribution to the uncertainty in the SI.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Attota, Ravikiran, E-mail: Ravikiran.attota@nist.gov; Dixson, Ronald G.

We experimentally demonstrate that the three-dimensional (3-D) shape variations of nanometer-scale objects can be resolved and measured with sub-nanometer scale sensitivity using conventional optical microscopes by analyzing 4-D optical data using the through-focus scanning optical microscopy (TSOM) method. These initial results show that TSOM-determined cross-sectional (3-D) shape differences of 30 nm–40 nm wide lines agree well with critical-dimension atomic force microscope measurements. The TSOM method showed a linewidth uncertainty of 1.22 nm (k = 2). Complex optical simulations are not needed for analysis using the TSOM method, making the process simple, economical, fast, and ideally suited for high volume nanomanufacturing process monitoring.

Design of forging process variables under uncertainties

NASA Astrophysics Data System (ADS)

Repalle, Jalaja; Grandhi, Ramana V.

2005-02-01

Forging is a complex nonlinear process that is vulnerable to various manufacturing anomalies, such as variations in billet geometry, billet/die temperatures, material properties, and workpiece and forging equipment positional errors. A combination of these uncertainties could induce heavy manufacturing losses through premature die failure, final part geometric distortion, and reduced productivity. Identifying, quantifying, and controlling the uncertainties will reduce variability risk in a manufacturing environment, which will minimize the overall production cost. In this article, various uncertainties that affect the forging process are identified, and their cumulative effect on the forging tool life is evaluated. Because the forging process simulation is time-consuming, a response surface model is used to reduce computation time by establishing a relationship between the process performance and the critical process variables. A robust design methodology is developed by incorporating reliability-based optimization techniques to obtain sound forging components. A case study of an automotive-component forging-process design is presented to demonstrate the applicability of the method.

Common but unappreciated sources of error in one, two, and multiple-color pyrometry

NASA Technical Reports Server (NTRS)

Spjut, R. Erik

1988-01-01

The most common sources of error in optical pyrometry are examined. They can be classified as either noise and uncertainty errors, stray radiation errors, or speed-of-response errors. Through judicious choice of detectors and optical wavelengths the effect of noise errors can be minimized, but one should strive to determine as many of the system properties as possible. Careful consideration of the optical-collection system can minimize stray radiation errors. Careful consideration must also be given to the slowest elements in a pyrometer when measuring rapid phenomena.

Optical-Fiber Power Meter Comparison between NIST and KRISS.

PubMed

Vayshenker, I; Kim, S K; Hong, K; Lee, D-H; Livigni, D J; Li, X; Lehman, J H

2012-01-01

We describe the results of a comparison of reference standards between the National Institute of Standards and Technology (NIST-USA) and Korea Research Institute of Standards and Science (KRISS-R.O. Korea) for optical fiber-based power measurements at wavelengths of 1302 nm and 1546 nm. We compare the laboratories' reference standards by means of a temperature-controlled optical trap detector. Measurement results showed the largest difference of less than 2.5 parts in 10(3), which is within the combined standard (k=1) uncertainty for the two laboratories' reference standards.

Optical-Fiber Power Meter Comparison Between NIST and PTB.

PubMed

Vayshenker, I; Haars, H; Li, X; Lehman, J H; Livigni, D J

2003-01-01

We describe the results of a comparison of reference standards between the National Institute of Standards and Technology (NIST-USA) and Physikalisch-Technische Bundesanstalt (PTB-Germany) at nominal wavelengths of 1300 nm and 1550 nm using an optical-fiber cable. Both laboratories used thermal detectors as reference standards. A novel temperature-controlled, optical-trap detector was used as a transfer standard to compare two reference standards. Measurement results showed differences of less than 1.5 × 10(-3), which is within the combined uncertainty for both laboratories.

Multiwavelength observations of a VHE gamma-ray flare from PKS 1510-089 in 2015

NASA Astrophysics Data System (ADS)

Ahnen, M. L.; Ansoldi, S.; Antonelli, L. A.; Arcaro, C.; Babić, A.; Banerjee, B.; Bangale, P.; Barres de Almeida, U.; Barrio, J. A.; Bednarek, W.; Bernardini, E.; Berti, A.; Biasuzzi, B.; Biland, A.; Blanch, O.; Bonnefoy, S.; Bonnoli, G.; Borracci, F.; Bretz, T.; Carosi, R.; Carosi, A.; Chatterjee, A.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; Cumani, P.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Lotto, B.; de Oña Wilhelmi, E.; Di Pierro, F.; Doert, M.; Domínguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Einecke, S.; Eisenacher Glawion, D.; Elsaesser, D.; Engelkemeier, M.; Fallah Ramazani, V.; Fernández-Barral, A.; Fidalgo, D.; Fonseca, M. V.; Font, L.; Fruck, C.; Galindo, D.; García López, R. J.; Garczarczyk, M.; Gaug, M.; Giammaria, P.; Godinović, N.; Gora, D.; Guberman, D.; Hadasch, D.; Hahn, A.; Hassan, T.; Hayashida, M.; Herrera, J.; Hose, J.; Hrupec, D.; Hughes, G.; Ishio, K.; Konno, Y.; Kubo, H.; Kushida, J.; Kuveždić, D.; Lelas, D.; Lindfors, E.; Lombardi, S.; Longo, F.; López, M.; Majumdar, P.; Makariev, M.; Maneva, G.; Manganaro, M.; Mannheim, K.; Maraschi, L.; Mariotti, M.; Martínez, M.; Mazin, D.; Menzel, U.; Mirzoyan, R.; Moralejo, A.; Moretti, E.; Nakajima, D.; Neustroev, V.; Niedzwiecki, A.; Nievas Rosillo, M.; Nilsson, K.; Nishijima, K.; Noda, K.; Nogués, L.; Paiano, S.; Palacio, J.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Paredes-Fortuny, X.; Pedaletti, G.; Peresano, M.; Perri, L.; Persic, M.; Poutanen, J.; Prada Moroni, P. G.; Prandini, E.; Puljak, I.; Garcia, J. R.; Reichardt, I.; Rhode, W.; Ribó, M.; Rico, J.; Saito, T.; Satalecka, K.; Schroeder, S.; Schweizer, T.; Shore, S. N.; Sillanpää, A.; Sitarek, J.; Šnidarić, I.; Sobczynska, D.; Stamerra, A.; Strzys, M.; Surić, T.; Takalo, L.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Torres, D. F.; Torres-Albà, N.; Toyama, T.; Treves, A.; Vanzo, G.; Vazquez Acosta, M.; Vovk, I.; Ward, J. E.; Will, M.; Wu, M. H.; Zarić, D.; Desiante, R.; Becerra González, J.; D'Ammando, F.; Larsson, S.; Raiteri, C. M.; Reinthal, R.; Lähteenmäki, A.; Järvelä, E.; Tornikoski, M.; Ramakrishnan, V.; Jorstad, S. G.; Marscher, A. P.; Bala, V.; MacDonald, N. R.; Kaur, N.; Sameer; Baliyan, K.; Acosta-Pulido, J. A.; Lazaro, C.; Martí-nez-Lombilla, C.; Grinon-Marin, A. B.; Pastor Yabar, A.; Protasio, C.; Carnerero, M. I.; Jermak, H.; Steele, I. A.; Larionov, V. M.; Borman, G. A.; Grishina, T. S.

2017-07-01

Context. PKS 1510-089 is one of only a few flat spectrum radio quasars detected in the very-high-energy (VHE, > 100 GeV) gamma-ray band. Aims: We study the broadband spectral and temporal properties of the PKS 1510-089 emission during a high gamma-ray state. Methods: We performed VHE gamma-ray observations of PKS 1510-089 with the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescopes during a long, high gamma-ray state in May 2015. In order to perform broadband modeling of the source, we have also gathered contemporaneous multiwavelength data in radio, IR, optical photometry and polarization, UV, X-ray, and GeV gamma-ray ranges. We construct a broadband spectral energy distribution (SED) in two periods, selected according to VHE gamma-ray state. Results: PKS 1510-089 was detected by MAGIC during a few day-long observations performed in the middle of a long, high optical and gamma-ray state, showing for the first time a significant VHE gamma-ray variability. Similarly to the optical and gamma-ray high state of the source detected in 2012, it was accompanied by a rotation of the optical polarization angle and the emission of a new jet component observed in radio. However, owing to large uncertainty on the knot separation time, the association with the VHE gamma-ray emission cannot be firmly established. The spectral shape in the VHE band during the flare is similar to those obtained during previous measurements of the source. The observed flux variability sets constraints for the first time on the size of the region from which VHE gamma rays are emitted. We model the broadband SED in the framework of the external Compton scenario and discuss the possible emission site in view of multiwavelength data and alternative emission models.

Modification, calibration, and performance of the Ultra-High Sensitivity Aerosol Spectrometer for particle size distribution and volatility measurements during the Atmospheric Tomography Mission (ATom) airborne campaign

NASA Astrophysics Data System (ADS)

Kupc, Agnieszka; Williamson, Christina; Wagner, Nicholas L.; Richardson, Mathews; Brock, Charles A.

2018-01-01

Atmospheric aerosol is a key component of the chemistry and climate of the Earth's atmosphere. Accurate measurement of the concentration of atmospheric particles as a function of their size is fundamental to investigations of particle microphysics, optical characteristics, and chemical processes. We describe the modification, calibration, and performance of two commercially available, Ultra-High Sensitivity Aerosol Spectrometers (UHSASs) as used on the NASA DC-8 aircraft during the Atmospheric Tomography Mission (ATom). To avoid sample flow issues related to pressure variations during aircraft altitude changes, we installed a laminar flow meter on each instrument to measure sample flow directly at the inlet as well as flow controllers to maintain constant volumetric sheath flows. In addition, we added a compact thermodenuder operating at 300 °C to the inlet line of one of the instruments. With these modifications, the instruments are capable of making accurate (ranging from 7 % for Dp < 0.07 µm to 1 % for Dp > 0.13 µm), precise (< ±1.2 %), and continuous (1 Hz) measurements of size-resolved particle number concentration over the diameter range of 0.063-1.0 µm at ambient pressures of > 1000 to 225 hPa, while simultaneously providing information on particle volatility.We assessed the effect of uncertainty in the refractive index (n) of ambient particles that are sized by the UHSAS assuming the refractive index of ammonium sulfate (n = 1.52). For calibration particles with n between 1.44 and 1.58, the UHSAS diameter varies by +4/-10 % relative to ammonium sulfate. This diameter uncertainty associated with the range of refractive indices (i.e., particle composition) translates to aerosol surface area and volume uncertainties of +8.4/-17.8 and +12.4/-27.5 %, respectively. In addition to sizing uncertainty, low counting statistics can lead to uncertainties of < 20 % for aerosol surface area and < 30 % for volume with 10 s time resolution. The UHSAS reduction in counting efficiency was corrected for concentrations > 1000 cm-3.Examples of thermodenuded and non-thermodenuded aerosol number and volume size distributions as well as propagated uncertainties are shown for several cases encountered during the ATom project. Uncertainties in particle number concentration were limited by counting statistics, especially in the tropical upper troposphere where accumulation-mode concentrations were sometimes < 20 cm-3 (counting rates ˜ 5 Hz) at standard temperature and pressure.

Fourth International Conference on Squeezed States and Uncertainty Relations

NASA Technical Reports Server (NTRS)

Han, D. (Editor); Peng, Kunchi (Editor); Kim, Y. S. (Editor); Manko, V. I. (Editor)

1996-01-01

The fourth International Conference on Squeezed States and Uncertainty Relations was held at Shanxi University, Taiyuan, Shanxi, China, on June 5 - 9, 1995. This conference was jointly organized by Shanxi University, the University of Maryland (U.S.A.), and the Lebedev Physical Institute (Russia). The first meeting of this series was called the Workshop on Squeezed States and Uncertainty Relations, and was held in 1991 at College Park, Maryland. The second and third meetings in this series were hosted in 1992 by the Lebedev Institute in Moscow, and in 1993 by the University of Maryland Baltimore County, respectively. The scientific purpose of this series was initially to discuss squeezed states of light, but in recent years, the scope is becoming broad enough to include studies of uncertainty relations and squeeze transformations in all branches of physics, including, of course, quantum optics and foundations of quantum mechanics. Quantum optics will continue playing the pivotal role in the future, but the future meetings will include all branches of physics where squeeze transformations are basic transformation. This transition took place at the fourth meeting of this series held at Shanxi University in 1995. The fifth meeting in this series will be held in Budapest (Hungary) in 1997, and the principal organizer will be Jozsef Janszky of the Laboratory of Crystal Physics, P.O. Box 132, H-1052. Budapest, Hungary.

Non-intrusive torque measurement for rotating shafts using optical sensing of zebra-tapes

NASA Astrophysics Data System (ADS)

Zappalá, D.; Bezziccheri, M.; Crabtree, C. J.; Paone, N.

2018-06-01

Non-intrusive, reliable and precise torque measurement is critical to dynamic performance monitoring, control and condition monitoring of rotating mechanical systems. This paper presents a novel, contactless torque measurement system consisting of two shaft-mounted zebra tapes and two optical sensors mounted on stationary rigid supports. Unlike conventional torque measurement methods, the proposed system does not require costly embedded sensors or shaft-mounted electronics. Moreover, its non-intrusive nature, adaptable design, simple installation and low cost make it suitable for a large variety of advanced engineering applications. Torque measurement is achieved by estimating the shaft twist angle through analysis of zebra tape pulse train time shifts. This paper presents and compares two signal processing methods for torque measurement: rising edge detection and cross-correlation. The performance of the proposed system has been proven experimentally under both static and variable conditions and both processing approaches show good agreement with reference measurements from an in-line, invasive torque transducer. Measurement uncertainty has been estimated according to the ISO GUM (Guide to the expression of uncertainty in measurement). Type A analysis of experimental data has provided an expanded uncertainty relative to the system full-scale torque of  ±0.30% and  ±0.86% for the rising edge and cross-correlation approaches, respectively. Statistical simulations performed by the Monte Carlo method have provided, in the worst case, an expanded uncertainty of  ±1.19%.

Laser Resonator

NASA Technical Reports Server (NTRS)

Harper, L. L. (Inventor)

1983-01-01

An optical resonator cavity configuration has a unitary mirror with oppositely directed convex and concave reflective surfaces disposed into one fold and concertedly reversing both ends of a beam propagating from a laser rod disposed between two total internal reflection prisms. The optical components are rigidly positioned with perpendicularly crossed virtual rooflines by a compact optical bed. The rooflines of the internal reflection prisms, are arranged perpendicularly to the axis of the laser beam and to the optical axes of the optical resonator components.

Automatic assembly of micro-optical components

NASA Astrophysics Data System (ADS)

Gengenbach, Ulrich K.

1996-12-01

Automatic assembly becomes an important issue as hybrid micro systems enter industrial fabrication. Moving from a laboratory scale production with manual assembly and bonding processes to automatic assembly requires a thorough re- evaluation of the design, the characteristics of the individual components and of the processes involved. Parts supply for automatic operation, sensitive and intelligent grippers adapted to size, surface and material properties of the microcomponents gain importance when the superior sensory and handling skills of a human are to be replaced by a machine. This holds in particular for the automatic assembly of micro-optical components. The paper outlines these issues exemplified at the automatic assembly of a micro-optical duplexer consisting of a micro-optical bench fabricated by the LIGA technique, two spherical lenses, a wavelength filter and an optical fiber. Spherical lenses, wavelength filter and optical fiber are supplied by third party vendors, which raises the question of parts supply for automatic assembly. The bonding processes for these components include press fit and adhesive bonding. The prototype assembly system with all relevant components e.g. handling system, parts supply, grippers and control is described. Results of first automatic assembly tests are presented.

Integrated Modeling Activities for the James Webb Space Telescope: Structural-Thermal-Optical Analysis

NASA Technical Reports Server (NTRS)

Johnston, John D.; Howard, Joseph M.; Mosier, Gary E.; Parrish, Keith A.; McGinnis, Mark A.; Bluth, Marcel; Kim, Kevin; Ha, Kong Q.

2004-01-01

The James Web Space Telescope (JWST) is a large, infrared-optimized space telescope scheduled for launch in 2011. This is a continuation of a series of papers on modeling activities for JWST. The structural-thermal-optical, often referred to as STOP, analysis process is used to predict the effect of thermal distortion on optical performance. The benchmark STOP analysis for JWST assesses the effect of an observatory slew on wavefront error. Temperatures predicted using geometric and thermal math models are mapped to a structural finite element model in order to predict thermally induced deformations. Motions and deformations at optical surfaces are then input to optical models, and optical performance is predicted using either an optical ray trace or a linear optical analysis tool. In addition to baseline performance predictions, a process for performing sensitivity studies to assess modeling uncertainties is described.

Direct comparison of the hygroscopic properties of ammonium sulfate and sodium chloride aerosol at relative humidities approaching saturation.

PubMed

Walker, Jim S; Wills, Jon B; Reid, Jonathan P; Wang, Liangyu; Topping, David O; Butler, Jason R; Zhang, Yun-Hong

2010-12-09

Holographic optical tweezers are used to make comparative measurements of the hygroscopic properties of single component aqueous aerosol containing sodium chloride and ammonium sulfate over a range of relative humidity from 84% to 96%. The change in RH over the course of the experiment is monitored precisely using a sodium chloride probe droplet with accuracy better than ±0.09%. The measurements are used to assess the accuracy of thermodynamic treatments of the relationship between water activity and solute mass fraction with particular attention focused on the dilute solute limit approaching saturation vapor pressure. The consistency of the frequently used Clegg-Brimblecombe-Wexler (CBW) treatment for predicting the hygroscopic properties of sodium chloride and ammonium sulfate aerosol is confirmed. Measurements of the equilibrium size of ammonium sulfate aerosol are found to agree with predictions to within an uncertainty of ±0.2%. Given the accuracy of treating equilibrium composition, the inconsistencies highlighted in recent calibration measurements of critical supersaturations of sodium chloride and ammonium sulfate aerosol cannot be attributed to uncertainties associated with the thermodynamic predictions and must have an alternative origin. It is concluded that the CBW treatment can allow the critical supersaturation to be estimated for sodium chloride and ammonium sulfate aerosol with an accuracy of better than ±0.002% in RH. This corresponds to an uncertainty of ≤1% in the critical supersaturation for typical supersaturations of 0.2% and above. This supports the view that these systems can be used to accurately calibrate instruments that measure cloud condensation nuclei concentrations at selected supersaturations. These measurements represent the first study in which the equilibrium properties of two particles of chemically distinct composition have been compared simultaneously and directly alongside each other in the same environment.

Optical systems fabricated by printing-based assembly

DOEpatents

Rogers, John; Nuzzo, Ralph; Meitl, Matthew; Menard, Etienne; Baca, Alfred J; Motala, Michael; Ahn, Jong-Hyun; Park, Sang-Il; Yu, Chang-Jae; Ko, Heung Cho; Stoykovich, Mark; Yoon, Jongseung

2014-05-13

Provided are optical devices and systems fabricated, at least in part, via printing-based assembly and integration of device components. In specific embodiments the present invention provides light emitting systems, light collecting systems, light sensing systems and photovoltaic systems comprising printable semiconductor elements, including large area, high performance macroelectronic devices. Optical systems of the present invention comprise semiconductor elements assembled, organized and/or integrated with other device components via printing techniques that exhibit performance characteristics and functionality comparable to single crystalline semiconductor based devices fabricated using conventional high temperature processing methods. Optical systems of the present invention have device geometries and configurations, such as form factors, component densities, and component positions, accessed by printing that provide a range of useful device functionalities. Optical systems of the present invention include devices and device arrays exhibiting a range of useful physical and mechanical properties including flexibility, shapeability, conformability and stretchablity.

Optical systems fabricated by printing-based assembly

DOEpatents

Rogers, John [Champaign, IL; Nuzzo, Ralph [Champaign, IL; Meitl, Matthew [Durham, NC; Menard, Etienne [Durham, NC; Baca, Alfred J [Urbana, IL; Motala, Michael [Champaign, IL; Ahn, Jong-Hyun [Suwon, KR; Park, Sang-II [Savoy, IL; Yu,; Chang-Jae, [Urbana, IL; Ko, Heung-Cho [Gwangju, KR; Stoykovich,; Mark, [Dover, NH; Yoon, Jongseung [Urbana, IL

2011-07-05

Provided are optical devices and systems fabricated, at least in part, via printing-based assembly and integration of device components. In specific embodiments the present invention provides light emitting systems, light collecting systems, light sensing systems and photovoltaic systems comprising printable semiconductor elements, including large area, high performance macroelectronic devices. Optical systems of the present invention comprise semiconductor elements assembled, organized and/or integrated with other device components via printing techniques that exhibit performance characteristics and functionality comparable to single crystalline semiconductor based devices fabricated using conventional high temperature processing methods. Optical systems of the present invention have device geometries and configurations, such as form factors, component densities, and component positions, accessed by printing that provide a range of useful device functionalities. Optical systems of the present invention include devices and device arrays exhibiting a range of useful physical and mechanical properties including flexibility, shapeability, conformability and stretchablity.

Optical systems fabricated by printing-based assembly

DOEpatents

Rogers, John; Nuzzo, Ralph; Meitl, Matthew; Menard, Etienne; Baca, Alfred; Motala, Michael; Ahn, Jong -Hyun; Park, Sang -Il; Yu, Chang -Jae; Ko, Heung Cho; Stoykovich, Mark; Yoon, Jongseung

2015-08-25

Provided are optical devices and systems fabricated, at least in part, via printing-based assembly and integration of device components. In specific embodiments the present invention provides light emitting systems, light collecting systems, light sensing systems and photovoltaic systems comprising printable semiconductor elements, including large area, high performance macroelectronic devices. Optical systems of the present invention comprise semiconductor elements assembled, organized and/or integrated with other device components via printing techniques that exhibit performance characteristics and functionality comparable to single crystalline semiconductor based devices fabricated using conventional high temperature processing methods. Optical systems of the present invention have device geometries and configurations, such as form factors, component densities, and component positions, accessed by printing that provide a range of useful device functionalities. Optical systems of the present invention include devices and device arrays exhibiting a range of useful physical and mechanical properties including flexibility, shapeability, conformability and stretchablity.

Optical systems fabricated by printing-based assembly

DOEpatents

Rogers, John; Nuzzo, Ralph; Meitl, Matthew; Menard, Etienne; Baca, Alfred; Motala, Michael; Ahn, Jong-Hyun; Park, Sang-Il; Yu, Chang-Jae; Ko, Heung Cho; Stoykovich, Mark; Yoon, Jongseung

2017-03-21

Provided are optical devices and systems fabricated, at least in part, via printing-based assembly and integration of device components. In specific embodiments the present invention provides light emitting systems, light collecting systems, light sensing systems and photovoltaic systems comprising printable semiconductor elements, including large area, high performance macroelectronic devices. Optical systems of the present invention comprise semiconductor elements assembled, organized and/or integrated with other device components via printing techniques that exhibit performance characteristics and functionality comparable to single crystalline semiconductor based devices fabricated using conventional high temperature processing methods. Optical systems of the present invention have device geometries and configurations, such as form factors, component densities, and component positions, accessed by printing that provide a range of useful device functionalities. Optical systems of the present invention include devices and device arrays exhibiting a range of useful physical and mechanical properties including flexibility, shapeability, conformability and stretchablity.

Initial uncertainty in Pavlovian reward prediction persistently elevates incentive salience and extends sign-tracking to normally unattractive cues.

PubMed

Robinson, Mike J F; Anselme, Patrick; Fischer, Adam M; Berridge, Kent C

2014-06-01

Uncertainty is a component of many gambling games and may play a role in incentive motivation and cue attraction. Uncertainty can increase the attractiveness for predictors of reward in the Pavlovian procedure of autoshaping, visible as enhanced sign-tracking (or approach and nibbles) by rats of a metal lever whose sudden appearance acts as a conditioned stimulus (CS+) to predict sucrose pellets as an unconditioned stimulus (UCS). Here we examined how reward uncertainty might enhance incentive salience as sign-tracking both in intensity and by broadening the range of attractive CS+s. We also examined whether initially induced uncertainty enhancements of CS+ attraction can endure beyond uncertainty itself, and persist even when Pavlovian prediction becomes 100% certain. Our results show that uncertainty can broaden incentive salience attribution to make CS cues attractive that would otherwise not be (either because they are too distal from reward or too risky to normally attract sign-tracking). In addition, uncertainty enhancement of CS+ incentive salience, once induced by initial exposure, persisted even when Pavlovian CS-UCS correlations later rose toward 100% certainty in prediction. Persistence suggests an enduring incentive motivation enhancement potentially relevant to gambling, which in some ways resembles incentive-sensitization. Higher motivation to uncertain CS+s leads to more potent attraction to these cues when they predict the delivery of uncertain rewards. In humans, those cues might possibly include the sights and sounds associated with gambling, which contribute a major component of the play immersion experienced by problematic gamblers. Copyright © 2014 Elsevier B.V. All rights reserved.

Initial uncertainty in Pavlovian reward prediction persistently elevates incentive salience and extends sign-tracking to normally unattractive cues

PubMed Central

Robinson, Mike J. F.; Anselme, Patrick; Fischer, Adam M.; Berridge, Kent C.

2014-01-01

Uncertainty is a component of many gambling games and may play a role in incentive motivation and cue attraction. Uncertainty can increase the attractiveness for predictors of reward in the Pavlovian procedure of autoshaping, visible as enhanced sign-tracking (or approach and nibbles) by rats of a metal lever whose sudden appearance acts as a conditioned stimulus (CS+) to predict sucrose pellets as an unconditioned stimulus (UCS). Here we examined how reward uncertainty might enhance incentive salience as sign-tracking both in intensity and by broadening the range of attractive CS+s. We also examined whether initially-induced uncertainty enhancements of CS+ attraction can endure beyond uncertainty itself, and persist even when Pavlovian prediction becomes 100% certain. Our results show that uncertainty can broaden incentive salience attribution to make CS cues attractive that would otherwise not be (either because they are too distal from reward or too risky to normally attract sign-tracking). In addition, uncertainty enhancement of CS+ incentive salience, once induced by initial exposure, persisted even when Pavlovian CS-UCS correlations later rose toward 100% certainty in prediction. Persistence suggests an enduring incentive motivation enhancement potentially relevant to gambling, which in some ways resembles incentive-sensitization. Higher motivation to uncertain CS+s leads to more potent attraction to these cues when they predict the delivery of uncertain rewards. In humans, those cues might possibly include the sights and sounds associated with gambling, which contribute a major component of the play immersion experienced by problematic gamblers. PMID:24631397

Fiber optics for the future - wavelength division multiplexing

NASA Technical Reports Server (NTRS)

Spencer, J. L.

1982-01-01

Optical wavelength division multiplexing (WDM) systems, with signals transmitted on different wavelengths through a single fiber, can have increased information capacity and fault isolation properties over single wavelength optical systems. This paper describes a typical WDM system. The applicability of future standards to such a system are discussed. Also, a state-of-the-art survey of optical multimode components which could be used to implement the system are made. The components to be surveyed are sources, multiplexers, and detectors. Emphasis is given to the demultiplexer techniques which are the major developmental components in the WDM system.

Elliptical concentrators.

PubMed

Garcia-Botella, Angel; Fernandez-Balbuena, Antonio Alvarez; Bernabeu, Eusebio

2006-10-10

Nonimaging optics is a field devoted to the design of optical components for applications such as solar concentration or illumination. In this field, many different techniques have been used to produce optical devices, including the use of reflective and refractive components or inverse engineering techniques. However, many of these optical components are based on translational symmetries, rotational symmetries, or free-form surfaces. We study a new family of nonimaging concentrators called elliptical concentrators. This new family of concentrators provides new capabilities and can have different configurations, either homofocal or nonhomofocal. Translational and rotational concentrators can be considered as particular cases of elliptical concentrators.

Improving solar ultraviolet irradiance measurements by applying a temperature correction method for Teflon diffusers.

PubMed

Jäkel, Evelyn; den Outer, Peter N; Tax, Rick B; Görts, Peter C; Reinen, Henk A J M

2007-07-10

To establish trends in surface ultraviolet radiation levels, accurate and stable long-term measurements are required. The accuracy level of today's measurements has become high enough to notice even smaller effects that influence instrument sensitivity. Laboratory measurements of the sensitivity of the entrance optics have shown a decrease of as much as 0.07-0.1%/deg temperature increase. Since the entrance optics can heat to greater than 45 degrees C in Dutch summers, corrections are necessary. A method is developed to estimate the entrance optics temperatures from pyranometer measurements and meteorological data. The method enables us to correct historic data records for which temperature information is not available. The temperature retrieval method has an uncertainty of less than 2.5 degrees C, resulting in a 0.3% uncertainty in the correction to be performed. The temperature correction improves the agreement between modeled and measured doses and instrument intercomparison as performed within the Quality Assurance of Spectral Ultraviolet Measurements in Europe project. The retrieval method is easily transferable to other instruments.

Optical methods for the optimization of system SWaP-C using aspheric components and advanced optical polymers

NASA Astrophysics Data System (ADS)

Zelazny, Amy; Benson, Robert; Deegan, John; Walsh, Ken; Schmidt, W. David; Howe, Russell

2013-06-01

We describe the benefits to camera system SWaP-C associated with the use of aspheric molded glasses and optical polymers in the design and manufacture of optical components and elements. Both camera objectives and display eyepieces, typical for night vision man-portable EO/IR systems, are explored. We discuss optical trade-offs, system performance, and cost reductions associated with this approach in both visible and non-visible wavebands, specifically NIR and LWIR. Example optical models are presented, studied, and traded using this approach.

Beam-guidance optics for high-power fiber laser systems

NASA Astrophysics Data System (ADS)

Mohring, Bernd; Tassini, Leonardo; Protz, Rudolf; Zoz, Jürgen

2013-05-01

The realization of a high-energy laser weapon system by coupling a large number of industrial high-power fiber lasers is investigated. To perform the combination of the individual beams of the different fiber lasers within the optical path of the laser weapon, a special optical set-up is used. Each optical component is realized either as reflective component oras refractive optics. Both possibilities were investigated by simulations and experiments. From the results, the general aspects for the layout of the beam-guidance optics for a high-power fiber laser system are derived.

Optical probe

DOEpatents

Hencken, Kenneth; Flower, William L.

1999-01-01

A compact optical probe is disclosed particularly useful for analysis of emissions in industrial environments. The instant invention provides a geometry for optically-based measurements that allows all optical components (source, detector, rely optics, etc.) to be located in proximity to one another. The geometry of the probe disclosed herein provides a means for making optical measurements in environments where it is difficult and/or expensive to gain access to the vicinity of a flow stream to be measured. Significantly, the lens geometry of the optical probe allows the analysis location within a flow stream being monitored to be moved while maintaining optical alignment of all components even when the optical probe is focused on a plurality of different analysis points within the flow stream.

Annual Fossil-Fuel CO2 Emissions: Uncertainty of Emissions Gridded by On Degree Latitude by One Degree Longitude (1950-2013) (V. 2016)

DOE Data Explorer

Andres, R. J. [CDIAC; Boden, T. A. [CDIAC

2016-01-01

The annual, gridded fossil-fuel CO2 emissions uncertainty estimates from 1950-2013 provided in this database are derived from time series of global, regional, and national fossil-fuel CO2 emissions (Boden et al. 2016). Andres et al. (2016) describes the basic methodology in estimating the uncertainty in the (gridded fossil fuel data product ). This uncertainty is gridded at the same spatial and temporal scales as the mass magnitude maps. This gridded uncertainty includes uncertainty contributions from the spatial, temporal, proxy, and magnitude components used to create the magnitude map of FFCO2 emissions. Throughout this process, when assumptions had to be made or expert judgment employed, the general tendency in most cases was toward overestimating or increasing the magnitude of uncertainty.

Modeling, Simulation, and Analysis of a Decoy State Enabled Quantum Key Distribution System

DTIC Science & Technology

2015-03-26

through the fiber , we assume Alice and Bob have correct basis alignment and timing control for reference frame correction and precise photon detection...optical components ( laser , polarization modulator, electronic variable optical attenuator, fixed optical attenuator, fiber channel, beamsplitter...generated by the laser in the CPG propagate through multiple optical components, each with a unique propagation delay before reaching the OPM. Timing

Line-averaging measurement methods to estimate the gap in the CO2 balance closure - possibilities, challenges, and uncertainties

NASA Astrophysics Data System (ADS)

Ziemann, Astrid; Starke, Manuela; Schütze, Claudia

2017-11-01

An imbalance of surface energy fluxes using the eddy covariance (EC) method is observed in global measurement networks although all necessary corrections and conversions are applied to the raw data. Mainly during nighttime, advection can occur, resulting in a closing gap that consequently should also affect the CO2 balances. There is the crucial need for representative concentration and wind data to measure advective fluxes. Ground-based remote sensing techniques are an ideal tool as they provide the spatially representative CO2 concentration together with wind components within the same voxel structure. For this purpose, the presented SQuAd (Spatially resolved Quantification of the Advection influence on the balance closure of greenhouse gases) approach applies an integrated method combination of acoustic and optical remote sensing. The innovative combination of acoustic travel-time tomography (A-TOM) and open-path Fourier-transform infrared spectroscopy (OP-FTIR) will enable an upscaling and enhancement of EC measurements. OP-FTIR instrumentation offers the significant advantage of real-time simultaneous measurements of line-averaged concentrations for CO2 and other greenhouse gases (GHGs). A-TOM is a scalable method to remotely resolve 3-D wind and temperature fields. The paper will give an overview about the proposed SQuAd approach and first results of experimental tests at the FLUXNET site Grillenburg in Germany. Preliminary results of the comprehensive experiments reveal a mean nighttime horizontal advection of CO2 of about 10 µmol m-2 s-1 estimated by the spatially integrating and representative SQuAd method. Additionally, uncertainties in determining CO2 concentrations using passive OP-FTIR and wind speed applying A-TOM are systematically quantified. The maximum uncertainty for CO2 concentration was estimated due to environmental parameters, instrumental characteristics, and retrieval procedure with a total amount of approximately 30 % for a single measurement. Instantaneous wind components can be derived with a maximum uncertainty of 0.3 m s-1 depending on sampling, signal analysis, and environmental influences on sound propagation. Averaging over a period of 30 min, the standard error of the mean values can be decreased by a factor of at least 0.5 for OP-FTIR and 0.1 for A-TOM depending on the required spatial resolution. The presented validation of the joint application of the two independent, nonintrusive methods is in the focus of attention concerning their ability to quantify advective fluxes.

Advanced Small Modular Reactor Economics Model Development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harrison, Thomas J.

2014-10-01

The US Department of Energy Office of Nuclear Energy’s Advanced Small Modular Reactor (SMR) research and development activities focus on four key areas: Developing assessment methods for evaluating advanced SMR technologies and characteristics; and Developing and testing of materials, fuels and fabrication techniques; and Resolving key regulatory issues identified by US Nuclear Regulatory Commission and industry; and Developing advanced instrumentation and controls and human-machine interfaces. This report focuses on development of assessment methods to evaluate advanced SMR technologies and characteristics. Specifically, this report describes the expansion and application of the economic modeling effort at Oak Ridge National Laboratory. Analysis ofmore » the current modeling methods shows that one of the primary concerns for the modeling effort is the handling of uncertainty in cost estimates. Monte Carlo–based methods are commonly used to handle uncertainty, especially when implemented by a stand-alone script within a program such as Python or MATLAB. However, a script-based model requires each potential user to have access to a compiler and an executable capable of handling the script. Making the model accessible to multiple independent analysts is best accomplished by implementing the model in a common computing tool such as Microsoft Excel. Excel is readily available and accessible to most system analysts, but it is not designed for straightforward implementation of a Monte Carlo–based method. Using a Monte Carlo algorithm requires in-spreadsheet scripting and statistical analyses or the use of add-ons such as Crystal Ball. An alternative method uses propagation of error calculations in the existing Excel-based system to estimate system cost uncertainty. This method has the advantage of using Microsoft Excel as is, but it requires the use of simplifying assumptions. These assumptions do not necessarily bring into question the analytical results. In fact, the analysis shows that the propagation of error method introduces essentially negligible error, especially when compared to the uncertainty associated with some of the estimates themselves. The results of these uncertainty analyses generally quantify and identify the sources of uncertainty in the overall cost estimation. The obvious generalization—that capital cost uncertainty is the main driver—can be shown to be an accurate generalization for the current state of reactor cost analysis. However, the detailed analysis on a component-by-component basis helps to demonstrate which components would benefit most from research and development to decrease the uncertainty, as well as which components would benefit from research and development to decrease the absolute cost.« less

Non-Bayesian Optical Inference Machines

NASA Astrophysics Data System (ADS)

Kadar, Ivan; Eichmann, George

1987-01-01

In a recent paper, Eichmann and Caulfield) presented a preliminary exposition of optical learning machines suited for use in expert systems. In this paper, we extend the previous ideas by introducing learning as a means of reinforcement by information gathering and reasoning with uncertainty in a non-Bayesian framework2. More specifically, the non-Bayesian approach allows the representation of total ignorance (not knowing) as opposed to assuming equally likely prior distributions.

Entanglement detection in optical lattices of bosonic atoms with collective measurements

NASA Astrophysics Data System (ADS)

Tóth, Géza

2004-05-01

The minimum requirements for entanglement detection are discussed for a spin chain in which the spins cannot be individually accessed. The methods presented detect entangled states close to a cluster state and a many-body singlet state, and seem to be viable for experimental realization in optical lattices of two-state bosonic atoms. The entanglement criteria are based on entanglement witnesses and on the uncertainty of collective observables.

Developing an Approach to Model UV Fluxes in Smoke Laden Conditions over Central Asia

NASA Astrophysics Data System (ADS)

Park, Y. H.; Sokolik, I. N.

2016-12-01

The UV characteristics of smoke aerosols are valuable inputs to the UV Index forecasts, air quality studies, and assessments of the impact of regional environmental changes. The wavelength dependence of light absorption by aerosol particles is pronounced throughout the UV spectral region. Also in assumption that smoke consists of BC, OC, and Sulfate, the mass fraction of smoke is different with fire types. The purpose of this study is to introduce an approach to calculate the UV fluxes in the aerosol laden conditions, and investigate the irradiance compared to measured irradiance in the UV spectrum. To compute the spectral optical properties (e.g., the effective single scattering albedo, asymmetry parameter, and aerosol optical thickness) for the selected scenarios, the representative size distribution and the refractive index are selected and used in the Mie code. Smoke aerosol information (e.g. emission injection height, mass concentration of smoke components) from WRF Chem is applied to run tropospheric ultraviolet and visible (TUV) model. Using the TUV model, we make the comparisons between model and measured irradiance in UV spectrum in smoke aerosol conditions. An advantage of this approach and the uncertainty of the evaluation are discussed. Overall, the results of this investigation show that this approach is valuable to estimate UV fluxes in smoke laden conditions.

Assessment of the Water Quality Components in Turbid Estuarine Waters Based on Radiative Transfer Approximations

EPA Science Inventory

Bio-geo-optical data collected in the Neuse River Estuary, North Carolina, USA were used to develop a semi-empirical optical algorithm for assessing inherent optical properties associated with water quality components (WQCs). Three wavelengths (560, 665 and 709 nm) were explored ...

Optical simulations for experimental networks: lessons from MONET

NASA Astrophysics Data System (ADS)

Richards, Dwight H.; Jackel, Janet L.; Goodman, Matthew S.; Roudas, Ioannis; Wagner, Richard E.; Antoniades, Neophytos

1999-08-01

We have used optical simulations as a means of setting component requirements, assessing component compatibility, and designing experiments in the MONET (Multiwavelength Optical Networking) Project. This paper reviews the simulation method, gives some examples of the types of simulations that have been performed, and discusses the validation of the simulations.

Embedded 100 Gbps Photonic Components

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuznia, Charlie

This innovation to fiber optic component technology increases the performance, reduces the size and reduces the power consumption of optical communications within dense network systems, such as advanced distributed computing systems and data centers. VCSEL technology is enabling short-reach (< 100 m) and >100 Gbps optical interconnections over multi-mode fiber in commercial applications.

An Enhanced Method for Scheduling Observations of Large Sky Error Regions for Finding Optical Counterparts to Transients

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rana, Javed; Singhal, Akshat; Gadre, Bhooshan

2017-04-01

The discovery and subsequent study of optical counterparts to transient sources is crucial for their complete astrophysical understanding. Various gamma-ray burst (GRB) detectors, and more notably the ground-based gravitational wave detectors, typically have large uncertainties in the sky positions of detected sources. Searching these large sky regions spanning hundreds of square degrees is a formidable challenge for most ground-based optical telescopes, which can usually image less than tens of square degrees of the sky in a single night. We present algorithms for better scheduling of such follow-up observations in order to maximize the probability of imaging the optical counterpart, basedmore » on the all-sky probability distribution of the source position. We incorporate realistic observing constraints such as the diurnal cycle, telescope pointing limitations, available observing time, and the rising/setting of the target at the observatory’s location. We use simulations to demonstrate that our proposed algorithms outperform the default greedy observing schedule used by many observatories. Our algorithms are applicable for follow-up of other transient sources with large positional uncertainties, such as Fermi -detected GRBs, and can easily be adapted for scheduling radio or space-based X-ray follow-up.« less

Are the World's Oceans Optically Different?

NASA Technical Reports Server (NTRS)

Szeto, M.; Werdell, P. J.; Moore, T. S.; Campbell, J. W.

2011-01-01

Regional differences in the Sea-viewing Wide Field-of-view Sensor chlorophyll algorithm uncertainty were observed in a large global data set containing coincident in situ measurements of chlorophyll a concentration (Chla) and spectral radiometry. The uncertainty was found to be systematic when the data were sorted by ocean: Atlantic, Pacific, Southern, and Indian Oceans. Artifacts associated with different instrumentation and analytical methods had been previously ruled out. Given these oceanic biases in the chlorophyll algorithm, we hypothesized that the oceans may be optically different, and their optical differences may be intrinsically related to regional differences in phytoplankton community structure or biogeochemical processes. The oceanic biases, originally observed using radiometric measurements, were independently verified using total absorption measurements in a subset of the data. Moreover, they were explained through oceanic differences in the absorption of colored detrital matter (CDM) and phytoplankton. Both effects were considered together in explaining the ocean biases through a stepwise linear regression analysis. Significant oceanic differences in the amount of CDM and in phytoplankton cell sizes and pigmentation would give rise to optical differences, but we raise a concern for the spatial coverage of the data. We do not suggest the application of ocean-based algorithms but rather emphasize the importance of consolidating regional data sets before reaching this conclusion.

Multilayered metal-insulator nanocavities: toward tunable multi-resonance nano-devices for integrated optics

NASA Astrophysics Data System (ADS)

Song, Junyeob; Zhou, Wei

2017-02-01

Plasmonic nanocavities can control light flows and enhance light-mater interactions at subwavelength scale, and thus can potentially be used as nanoscale components in integrated optics systems either for passive optical coupling, or for active optical modulation and emission. In this work, we investigated a new type of multilayered metal-insulator optical nanocavities that can support multiple localized plasmon resonances with ultra-small mode volumes. The total number of resonance peaks and their resonance wavelengths can be freely and accurately controlled by simple geometric design rules. Multi-resonance plasmonic nanocavities can serve as a nanoscale wavelength-multiplexed optical components in integrated optics systems, such as optical couplers, light emitters, nanolasers, optical sensors, and optical modulators.

Thermo-optic devices on polymer platform

NASA Astrophysics Data System (ADS)

Zhang, Ziyang; Keil, Norbert

2016-03-01

Optical polymers possess in general relatively high thermo-optic coefficients and at the same time low thermal conductivity, both of which make them attractive material candidates for realizing highly efficient thermally tunable devices. Over the years, various thermo-optic components have been demonstrated on polymer platform, covering (1) tunable reflectors and filters as part of a laser cavity, (2) variable optical attenuators (VOAs) as light amplitude regulators in e.g. a coherent receiver, and (3) thermo-optic switches (TOSs) allowing multi-flow control in the photonic integrated circuits (PICs). This work attempts to review the recent progress on the above mentioned three component branches, including linearly and differentially tunable filters, VOAs based on 1×1 multimode interference structure (MMI) and Mach-Zehnder interferometer (MZI), and 1×2 TOS based on waveguide Y-branch, driven by a pair of sidelong placed heater electrodes. These thermo-optic components can well be integrated into larger PICs: the dual-polarization switchable tunable laser and the colorless optical 90° hybrid are presented in the end as examples.

Review of clinical brachytherapy uncertainties: Analysis guidelines of GEC-ESTRO and the AAPM☆

PubMed Central

Kirisits, Christian; Rivard, Mark J.; Baltas, Dimos; Ballester, Facundo; De Brabandere, Marisol; van der Laarse, Rob; Niatsetski, Yury; Papagiannis, Panagiotis; Hellebust, Taran Paulsen; Perez-Calatayud, Jose; Tanderup, Kari; Venselaar, Jack L.M.; Siebert, Frank-André

2014-01-01

Background and purpose A substantial reduction of uncertainties in clinical brachytherapy should result in improved outcome in terms of increased local control and reduced side effects. Types of uncertainties have to be identified, grouped, and quantified. Methods A detailed literature review was performed to identify uncertainty components and their relative importance to the combined overall uncertainty. Results Very few components (e.g., source strength and afterloader timer) are independent of clinical disease site and location of administered dose. While the influence of medium on dose calculation can be substantial for low energy sources or non-deeply seated implants, the influence of medium is of minor importance for high-energy sources in the pelvic region. The level of uncertainties due to target, organ, applicator, and/or source movement in relation to the geometry assumed for treatment planning is highly dependent on fractionation and the level of image guided adaptive treatment. Most studies to date report the results in a manner that allows no direct reproduction and further comparison with other studies. Often, no distinction is made between variations, uncertainties, and errors or mistakes. The literature review facilitated the drafting of recommendations for uniform uncertainty reporting in clinical BT, which are also provided. The recommended comprehensive uncertainty investigations are key to obtain a general impression of uncertainties, and may help to identify elements of the brachytherapy treatment process that need improvement in terms of diminishing their dosimetric uncertainties. It is recommended to present data on the analyzed parameters (distance shifts, volume changes, source or applicator position, etc.), and also their influence on absorbed dose for clinically-relevant dose parameters (e.g., target parameters such as D90 or OAR doses). Publications on brachytherapy should include a statement of total dose uncertainty for the entire treatment course, taking into account the fractionation schedule and level of image guidance for adaptation. Conclusions This report on brachytherapy clinical uncertainties represents a working project developed by the Brachytherapy Physics Quality Assurances System (BRAPHYQS) subcommittee to the Physics Committee within GEC-ESTRO. Further, this report has been reviewed and approved by the American Association of Physicists in Medicine. PMID:24299968

Residual Optically Stimulated Luminescent (OSL) Signals For Al2O3: C and a Readout System With Reproducible Partial Signal Clearance.

PubMed

Abraham, Sara A; Kearfott, Kimberlee J

2018-06-15

Optically stimulated luminescent dosimeters are devices that, when stimulated with light, emit light in proportion to the integrated ionizing radiation dose. The stimulation of optically stimulated luminescent material results in the loss of a small fraction of signal stored within the dosimetric traps. Previous studies have investigated the signal loss due to readout stimulation and the optical annealing of optically stimulated luminescent dosimeters. This study builds on former research by examining the behavior of optically stimulated luminescent signals after annealing, exploring the functionality of a previously developed signal loss model, and comparing uncertainties for dosimeters reused with or without annealing. For a completely annealed dosimeter, the minimum signal level was 56 ± 8 counts, and readings followed a Gaussian distribution. For dosimeters above this signal level, the fractional signal loss due to the reading process has a linear relationship with the calculated signal. At low signal levels (below 20,000 counts) in this optically stimulated luminescent dosimeter system, calculated signal percent errors increase significantly but otherwise are on average 0.72 ± 0.27%, 0.40 ± 0.19%, 0.33 ± 0.12%, and 0.24 ± 0.07% for 30, 75, 150, and 300 readings, respectively. Theoretical calculations of uncertainties showed that annealing before reusing dosimeters allows for dose errors below 1% with as few as 30 readings. Reusing dosimeters multiple times increases the dose errors especially with low numbers of readouts, so theoretically around 300 readings would be necessary to achieve errors around 1% or below in most scenarios. Note that these dose errors do not include the error associated with the signal-to-dose conversion factor.

The MODIS Aerosol Algorithm, Products and Validation

NASA Technical Reports Server (NTRS)

Remer, L. A.; Kaufman, Y. J.; Tanre, D.; Mattoo, S.; Chu, D. A.; Martins, J. V.; Li, R.-R.; Ichoku, C.; Levy, R. C.; Kleidman, R. G.

2003-01-01

The MODerate resolution Imaging Spectroradiometer (MODIS) aboard both NASA's Terra and Aqua satellites is making near global daily observations of the earth in a wide spectral range. These measurements are used to derive spectral aerosol optical thickness and aerosol size parameters over both land and ocean. The aerosol products available over land include aerosol optical thickness at three visible wavelengths, a measure of the fraction of aerosol optical thickness attributed to the fine mode and several derived parameters including reflected spectral solar flux at top of atmosphere. Over ocean, the aerosol optical thickness is provided in seven wavelengths from 0.47 microns to 2.13 microns. In addition, quantitative aerosol size information includes effective radius of the aerosol and quantitative fraction of optical thickness attributed to the fine mode. Spectral aerosol flux, mass concentration and number of cloud condensation nuclei round out the list of available aerosol products over the ocean. The spectral optical thickness and effective radius of the aerosol over the ocean are validated by comparison with two years of AERONET data gleaned from 133 AERONET stations. 8000 MODIS aerosol retrievals colocated with AERONET measurements confirm that one-standard deviation of MODIS optical thickness retrievals fall within the predicted uncertainty of delta tauapproximately equal to plus or minus 0.03 plus or minus 0.05 tau over ocean and delta tay equal to plus or minus 0.05 plus or minus 0.15 tau over land. 271 MODIS aerosol retrievals co-located with AERONET inversions at island and coastal sites suggest that one-standard deviation of MODIS effective radius retrievals falls within delta r_eff approximately equal to 0.11 microns. The accuracy of the MODIS retrievals suggests that the product can be used to help narrow the uncertainties associated with aerosol radiative forcing of global climate.

Probabilistic Structural Analysis Methods (PSAM) for Select Space Propulsion System Components

NASA Technical Reports Server (NTRS)

1999-01-01

Probabilistic Structural Analysis Methods (PSAM) are described for the probabilistic structural analysis of engine components for current and future space propulsion systems. Components for these systems are subjected to stochastic thermomechanical launch loads. Uncertainties or randomness also occurs in material properties, structural geometry, and boundary conditions. Material property stochasticity, such as in modulus of elasticity or yield strength, exists in every structure and is a consequence of variations in material composition and manufacturing processes. Procedures are outlined for computing the probabilistic structural response or reliability of the structural components. The response variables include static or dynamic deflections, strains, and stresses at one or several locations, natural frequencies, fatigue or creep life, etc. Sample cases illustrates how the PSAM methods and codes simulate input uncertainties and compute probabilistic response or reliability using a finite element model with probabilistic methods.

Multi-functional optical signal processing using optical spectrum control circuit

NASA Astrophysics Data System (ADS)

Hayashi, Shuhei; Ikeda, Tatsuhiko; Mizuno, Takayuki; Takahashi, Hiroshi; Tsuda, Hiroyuki

2015-02-01

Processing ultra-fast optical signals without optical/electronic conversion is in demand and time-to-space conversion has been proposed as an effective solution. We have designed and fabricated an arrayed-waveguide grating (AWG) based optical spectrum control circuit (OSCC) using silica planar lightwave circuit (PLC) technology. This device is composed of an AWG, tunable phase shifters and a mirror. The principle of signal processing is to spatially decompose the signal's frequency components by using the AWG. Then, the phase of each frequency component is controlled by the tunable phase shifters. Finally, the light is reflected back to the AWG by the mirror and synthesized. Amplitude of each frequency component can be controlled by distributing the power to high diffraction order light. The spectral controlling range of the OSCC is 100 GHz and its resolution is 1.67 GHz. This paper describes equipping the OSCC with optical coded division multiplex (OCDM) encoder/decoder functionality. The encoding principle is to apply certain phase patterns to the signal's frequency components and intentionally disperse the signal. The decoding principle is also to apply certain phase patterns to the frequency components at the receiving side. If the applied phase pattern compensates the intentional dispersion, the waveform is regenerated, but if the pattern is not appropriate, the waveform remains dispersed. We also propose an arbitrary filter function by exploiting the OSCC's amplitude and phase control attributes. For example, a filtered optical signal transmitted through multiple optical nodes that use the wavelength multiplexer/demultiplexer can be equalized.

Space Flight Applications of Optical Fiber; 30 Years of Space Flight Success

NASA Technical Reports Server (NTRS)

Ott, Melanie N.

2010-01-01

For over thirty years NASA has had success with space flight missions that utilize optical fiber component technology. One of the early environmental characterization experiments that included optical fiber was launched as the Long Duration Exposure Facility in 1978. Since then, multiple missions have launched with optical fiber components that functioned as expected, without failure throughout the mission life. The use of optical fiber in NASA space flight communications links and exploration and science instrumentation is reviewed.

The Araucaria project. The distance to the small Magellanic Cloud from late-type eclipsing binaries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graczyk, Dariusz; Pietrzyński, Grzegorz; Gieren, Wolfgang

2014-01-01

We present a distance determination to the Small Magellanic Cloud (SMC) based on an analysis of four detached, long-period, late-type eclipsing binaries discovered by the Optical Gravitational Lensing Experiment (OGLE) survey. The components of the binaries show negligible intrinsic variability. A consistent set of stellar parameters was derived with low statistical and systematic uncertainty. The absolute dimensions of the stars are calculated with a precision of better than 3%. The surface brightness-infrared color relation was used to derive the distance to each binary. The four systems clump around a distance modulus of (m – M) = 18.99 with a dispersionmore » of only 0.05 mag. Combining these results with the distance published by Graczyk et al. for the eclipsing binary OGLE SMC113.3 4007, we obtain a mean distance modulus to the SMC of 18.965 ± 0.025 (stat.) ± 0.048 (syst.) mag. This corresponds to a distance of 62.1 ± 1.9 kpc, where the error includes both uncertainties. Taking into account other recent published determinations of the SMC distance we calculated the distance modulus difference between the SMC and the Large Magellanic Cloud equal to 0.458 ± 0.068 mag. Finally, we advocate μ{sub SMC} = 18.95 ± 0.07 as a new 'canonical' value of the distance modulus to this galaxy.« less

System for measuring the coordinates of tire surfaces in transient conditions when rolling over obstacles: description of the system and performance analysis.

PubMed

Castellini, Paolo; Di Giuseppe, Andrea

2008-06-01

This paper describes the development of a system for measuring surface coordinates (commonly known as "shape measurements") which is able to give the temporal evolution of the position of the tire sidewall in transient conditions (such as during braking, when there are potholes or when the road surface is uneven) which may or may not be reproducible. The system is based on the well-known technique of projecting and observing structured light using a digital camera with an optical axis which is slanted with respect to the axis of the projector. The transient nature of the phenomenon has led to the development of specific innovative solutions as regards image processing algorithms. This paper briefly describes the components which make up the measuring system and presents the results of the measurements carried out on the drum bench. It then analyses the performance of the measuring system and the sources of uncertainty which led to the development of the system for a specific dynamic application: impact with an obstacle (cleat test). The measuring system guaranteed a measurement uncertainty of 0.28 mm along the Z axis (the axial direction of the tire) with a measurement range of 250(X) x 80(Y) x 25(Z) mm(3), with the tire rolling at a speed of up to 30 km/h.

[New type distributed optical fiber temperature sensor (DTS) based on Raman scattering and its' application].

PubMed

Wang, Jian-Feng; Liu, Hong-Lin; Zhang, Shu-Qin; Yu, Xiang-Dong; Sun, Zhong-Zhou; Jin, Shang-Zhong; Zhang, Zai-Xuan

2013-04-01

Basic principles, development trends and applications status of distributed optical fiber Raman temperature sensor (DTS) are introduced. Performance parameters of DTS system include the sensing optical fiber length, temperature measurement uncertainty, spatial resolution and measurement time. These parameters have a certain correlation and it is difficult to improve them at the same time by single technology. So a variety of key techniques such as Raman amplification, pulse coding technique, Raman related dual-wavelength self-correction technique and embedding optical switching technique are researched to improve the performance of the DTS system. A 1 467 nm continuous laser is used as pump laser and the light source of DTS system (1 550 nm pulse laser) is amplified. When the length of sensing optical fiber is 50 km the Raman gain is about 17 dB. Raman gain can partially compensate the transmission loss of optical fiber, so that the sensing length can reach 50 km. In DTS system using pulse coding technique, pulse laser is coded by 211 bits loop encoder and correlation calculation is used to demodulate temperature. The encoded laser signal is related, whereas the noise is not relevant. So that signal-to-noise ratio (SNR) of DTS system can be improved significantly. The experiments are carried out in DTS system with single mode optical fiber and multimode optical fiber respectively. Temperature measurement uncertainty can all reach 1 degrees C. In DTS system using Raman related dual-wavelength self-correction technique, the wavelength difference of the two light sources must be one Raman frequency shift in optical fiber. For example, wavelength of the main laser is 1 550 nm and wavelength of the second laser must be 1 450 nm. Spatial resolution of DTS system is improved to 2 m by using dual-wavelength self-correction technique. Optical switch is embedded in DTS system, so that the temperature measurement channel multiply extended and the total length of the sensing optical fiber effectively extended. Optical fiber sensor network is composed.

Online damage inspection of optics for ATP system

NASA Astrophysics Data System (ADS)

Chen, Jing; Jiang, Yu; Mao, Yao; Gan, Xun; Liu, Qiong

2016-09-01

In the Electro-Optical acquisition-tracking-pointing system (ATP), the optical components will be damaged with the several influencing factors. In this situation, the rate will increase sharply when the arrival of damage to some extent. As the complex processing techniques and long processing cycle of optical components, the damage will cause the great increase of the system development cost and cycle. Therefore, it is significant to detect the laser-induced damage in the ATP system. At present, the major research on the on-line damage detection technology of optical components is for the large optical system in the international. The relevant detection systems have complicated structures and many of components, and require enough installation space reserved, which do not apply for ATP system. To solve the problem mentioned before, This paper use a method based on machine vision to detect the damage on-line for the present ATP system. To start with, CCD and PC are used for image acquisition. Secondly, smoothing filters are used to restrain false damage points produced by noise. Then, with the shape feature included in the damage image, the OTSU Method which can define the best segmentation threshold automatically is used to achieve the goal to locate the damage regions. At last, we can supply some opinions for the lifetime of the optical components by analyzing the damage data, such as damage area, damage position. The method has the characteristics of few-detectors and simple-structures which can be installed without any changes of the original light path. With the method, experimental results show that it is stable and effective to achieve the goal of detecting the damage of optical components on-line in the ATP system.

Parallel Optical Random Access Memory (PORAM)

NASA Technical Reports Server (NTRS)

Alphonse, G. A.

1989-01-01

It is shown that the need to minimize component count, power and size, and to maximize packing density require a parallel optical random access memory to be designed in a two-level hierarchy: a modular level and an interconnect level. Three module designs are proposed, in the order of research and development requirements. The first uses state-of-the-art components, including individually addressed laser diode arrays, acousto-optic (AO) deflectors and magneto-optic (MO) storage medium, aimed at moderate size, moderate power, and high packing density. The next design level uses an electron-trapping (ET) medium to reduce optical power requirements. The third design uses a beam-steering grating surface emitter (GSE) array to reduce size further and minimize the number of components.

Investigation of the effects of long duration space exposure on active optical system components

NASA Technical Reports Server (NTRS)

Blue, M. D.

1994-01-01

This experiment was exposed to the space environment for 6 years on the Long Duration Exposure Facility (LDEF). It investigated quantitatively the effects of the long-duration space exposure on the relevant performance parameters of a representative set of electron-optic system components, including lasers, radiation detectors, filters, modulators, windows, and other related components. It evaluated the results and implications of the measurements indicating real or suspected degradation mechanisms. This information will be used to establish guidelines for the selection and use of components for space-based, electro-optic systems.

The Second International Workshop on Squeezed States and Uncertainty Relations

NASA Technical Reports Server (NTRS)

Han, D. (Editor); Kim, Y. S.; Manko, V. I.

1993-01-01

This conference publication contains the proceedings of the Second International Workshop on Squeezed States and Uncertainty Relations held in Moscow, Russia, on 25-29 May 1992. The purpose of this workshop was to study possible applications of squeezed states of light. The Workshop brought together many active researchers in squeezed states of light and those who may find the concept of squeezed states useful in their research, particularly in understanding the uncertainty relations. It was found at this workshop that the squeezed state has a much broader implication than the two-photon coherent states in quantum optics, since the squeeze transformation is one of the most fundamental transformations in physics.

Determination of the fine structure constant using helium fine structure.

PubMed

Smiciklas, Marc; Shiner, David

2010-09-17

We measure 31,908,131.25(30) kHz for the 2(3)}P J=0 to 2 fine structure interval in helium. The difference between this and theory to order mα7 (20 Hz numerical uncertainty) implies 0.22(30) kHz for uncalculated terms. The measurement is performed by using atomic beam and electro-optic laser techniques. Various checks include a 3He 2{3}S hyperfine measurement. We can obtain an independent value for the fine structure constant α with a 5 ppb experimental uncertainty. However, dominant mα8 terms (potentially 1.2 kHz) limit the overall uncertainty to a less competitive 20 ppb in α.

Porous silicon based micro-opto-electro-mechanical-systems (MOEMS) components for free space optical interconnects

NASA Astrophysics Data System (ADS)

Song, Da

2008-02-01

One of the major challenges confronting the current integrated circuits (IC) industry is the metal "interconnect bottleneck". To overcome this obstacle, free space optical interconnects (FSOIs) can be used to address the demand for high speed data transmission, multi-functionality and multi-dimensional integration for the next generation IC. One of the crucial elements in FSOIs system is to develop a high performance and flexible optical network to transform the incoming optical signal into a distributed set of optical signals whose direction, alignment and power can be independently controlled. Among all the optical materials for the realization of FSOI components, porous silicon (PSi) is one of the most promising candidates because of its unique optical properties, flexible fabrication methods and integration with conventional IC material sets. PSi-based Distributed Bragg Reflector (DBR) and Fabry-Perot (F-P) structures with unique optical properties are realized by electrochemical etching of silicon. By incorporating PSi optical structures with Micro-Opto-Electro-Mechanical-Systems (MOEMS), several components required for FSOI have been developed. The first type of component is the out-of-plane freestanding optical switch. Implementing a PSi DBR structure as an optically active region, the device can realize channel selection by changing the tilting angle of the micromirror supported by the thermal bimorph actuator. All the fabricated optical switches have reached kHz working frequency and life time of millions of cycles. The second type of component is the in-plane tunable optical filter. By introducing PSi F-P structure into the in-plane PSi film, a thermally tunable optical filter with a sensitivity of 7.9nm/V has been realized for add/drop optical signal selection. Also, for the first time, a new type of PSi based reconfigurable diffractive optical element (DOE) has been developed. By using patterned photoresist as a protective mask for electrochemical etching, the freestanding PSi-based MOEMS DOE has been created as a beam splitter to redistribute the incoming optical signal with onto desired detector arrays. All the developed devices are realized in array fashion and can be addressed and controlled individually. The combination of PSi and MOEMS opens the door for a new generation of silicon compatible optical interconnects.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Knudsen, J.K.; Smith, C.L.

The steps involved to incorporate parameter uncertainty into the Nuclear Regulatory Commission (NRC) accident sequence precursor (ASP) models is covered in this paper. Three different uncertainty distributions (i.e., lognormal, beta, gamma) were evaluated to Determine the most appropriate distribution. From the evaluation, it was Determined that the lognormal distribution will be used for the ASP models uncertainty parameters. Selection of the uncertainty parameters for the basic events is also discussed. This paper covers the process of determining uncertainty parameters for the supercomponent basic events (i.e., basic events that are comprised of more than one component which can have more thanmore » one failure mode) that are utilized in the ASP models. Once this is completed, the ASP model is ready to be utilized to propagate parameter uncertainty for event assessments.« less

Integrating model behavior, optimization, and sensitivity/uncertainty analysis: overview and application of the MOUSE software toolbox

USDA-ARS?s Scientific Manuscript database

This paper provides an overview of the Model Optimization, Uncertainty, and SEnsitivity Analysis (MOUSE) software application, an open-source, Java-based toolbox of visual and numerical analysis components for the evaluation of environmental models. MOUSE is based on the OPTAS model calibration syst...

An approach for estimating measurement uncertainty in medical laboratories using data from long-term quality control and external quality assessment schemes.

PubMed

Padoan, Andrea; Antonelli, Giorgia; Aita, Ada; Sciacovelli, Laura; Plebani, Mario

2017-10-26

The present study was prompted by the ISO 15189 requirements that medical laboratories should estimate measurement uncertainty (MU). The method used to estimate MU included the: a) identification of quantitative tests, b) classification of tests in relation to their clinical purpose, and c) identification of criteria to estimate the different MU components. Imprecision was estimated using long-term internal quality control (IQC) results of the year 2016, while external quality assessment schemes (EQAs) results obtained in the period 2015-2016 were used to estimate bias and bias uncertainty. A total of 263 measurement procedures (MPs) were analyzed. On the basis of test purpose, in 51 MPs imprecision only was used to estimate MU; in the remaining MPs, the bias component was not estimable for 22 MPs because EQAs results did not provide reliable statistics. For a total of 28 MPs, two or more MU values were calculated on the basis of analyte concentration levels. Overall, results showed that uncertainty of bias is a minor factor contributing to MU, the bias component being the most relevant contributor to all the studied sample matrices. The model chosen for MU estimation allowed us to derive a standardized approach for bias calculation, with respect to the fitness-for-purpose of test results. Measurement uncertainty estimation could readily be implemented in medical laboratories as a useful tool in monitoring the analytical quality of test results since they are calculated using a combination of both the long-term imprecision IQC results and bias, on the basis of EQAs results.

Effects of uncertainty, transmission type, driver age and gender on brake reaction and movement time.

PubMed

Warshawsky-Livne, Lora; Shinar, David

2002-01-01

Braking time (BT) is a critical component in safe driving, and various approaches have been applied to minimize it. This study analyzed the components of BT in order to assess the effects of age, gender, vehicle transmission type, and event uncertainty, on its two primary components, perception-reaction time and brake-movement time. Perception-reaction time and brake-movement time were measured at the onset of lights for 72 subjects in a simulator. The six experimental conditions were three levels of uncertainty conditions (none, some, and some + false alarms) and two types of transmission (manual and automatic). The 72 subjects, half male and half female, were further divided into three age groups (mean of 23, 30, and 62 years). Each subject had 10 trials in each of the three levels of uncertainty conditions. Transmission type did not significantly affect either perception-reaction time or brake-movement time. Perception-reaction time increased significantly from 0.32 to 0.42 s (P < .05) as uncertainty increased but brake-movement time did not change. Perception-reaction time increased (from 0.35 to 0.43 s) with age but brake-movement time did not change with age. Gender did not affect perception-reaction time but did affect brake-movement time (males 0.19 s vs. females 0.16 s). At 90 km/h, a car travels 0.25 m in 0.01 s. Consequently, even such small effects multiplied by millions of vehicle-kilometers can contribute to significant savings in lives and damages.

Photonics technology development for optical fuzing.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, J.J.; Geib, Kent Martin; von der Lippe, C.M.

2005-07-01

This paper describes the photonic component development, which exploits pioneering work and unique expertise at Sandia National Laboratories, ARDEC and the Army Research Laboratory by combining key optoelectronic technologies to design and demonstrate components for this fuzing application. The technologies under investigation for the optical fuze design covered in this paper are vertical cavity surface emitting lasers (VECSELs), integrated resonant cavity photodetectors (RCPD), and diffractive micro-optics. The culmination of this work will be low cost, robust, fully integrated, g-hardened components designed suitable for proximity fuzing applications. The use of advanced photonic components will enable replacement of costly assemblies that employmore » discrete lasers, photodetectors, and bulk optics. The integrated devices will be mass produced and impart huge savings for a variety of Army applications.« less

Advanced optical manufacturing digital integrated system

NASA Astrophysics Data System (ADS)

Tao, Yizheng; Li, Xinglan; Li, Wei; Tang, Dingyong

2012-10-01

It is necessarily to adapt development of advanced optical manufacturing technology with modern science technology development. To solved these problems which low of ration, ratio of finished product, repetition, consistent in big size and high precision in advanced optical component manufacturing. Applied business driven and method of Rational Unified Process, this paper has researched advanced optical manufacturing process flow, requirement of Advanced Optical Manufacturing integrated System, and put forward architecture and key technology of it. Designed Optical component core and Manufacturing process driven of Advanced Optical Manufacturing Digital Integrated System. the result displayed effective well, realized dynamic planning Manufacturing process, information integration improved ratio of production manufactory.

Quantum cryptography and applications in the optical fiber network

NASA Astrophysics Data System (ADS)

Luo, Yuhui

2005-09-01

Quantum cryptography, as part of quantum information and communications, can provide absolute security for information transmission because it is established on the fundamental laws of quantum theory, such as the principle of uncertainty, No-cloning theorem and quantum entanglement. In this thesis research, a novel scheme to implement quantum key distribution based on multiphoton entanglement with a new protocol is proposed. Its advantages are: a larger information capacity can be obtained with a longer transmission distance and the detection of multiple photons is easier than that of a single photon. The security and attacks pertaining to such a system are also studied. Next, a quantum key distribution over wavelength division multiplexed (WDM) optical fiber networks is realized. Quantum key distribution in networks is a long-standing problem for practical applications. Here we combine quantum cryptography and WDM to solve this problem because WDM technology is universally deployed in the current and next generation fiber networks. The ultimate target is to deploy quantum key distribution over commercial networks. The problems arising from the networks are also studied in this part. Then quantum key distribution in multi-access networks using wavelength routing technology is investigated in this research. For the first time, quantum cryptography for multiple individually targeted users has been successfully implemented in sharp contrast to that using the indiscriminating broadcasting structure. It overcomes the shortcoming that every user in the network can acquire the quantum key signals intended to be exchanged between only two users. Furthermore, a more efficient scheme of quantum key distribution is adopted, hence resulting in a higher key rate. Lastly, a quantum random number generator based on quantum optics has been experimentally demonstrated. This device is a key component for quantum key distribution as it can create truly random numbers, which is an essential requirement to perform quantum key distribution. This new generator is composed of a single optical fiber coupler with fiber pigtails, which can be easily used in optical fiber communications.

Deep Proton Writing for the rapid prototyping of polymer micro-components for optical interconnects and optofluidics

NASA Astrophysics Data System (ADS)

Van Erps, Jürgen; Vervaeke, Michael; Ottevaere, Heidi; Hermanne, Alex; Thienpont, Hugo

2013-07-01

The use of photonics in data communication and numerous other industrial applications brought plenty of prospects for innovation and opened up different unexplored market opportunities. This is a major driving force for the fabrication of micro-optical and micro-mechanical structures and their accurate alignment and integration into opto-mechanical modules and systems. To this end, we present Deep Proton Writing (DPW) as a powerful rapid prototyping technology for such micro-components. The DPW process consists of bombarding polymer samples (PMMA or SU-8) with swift protons, which results after chemical processing steps in high-quality micro-optical components. One of the strengths of the DPW micro-fabrication technology is the ability to fabricate monolithic building blocks that include micro-optical and mechanical functionalities which can be precisely integrated into more complex photonic systems. In this paper we comment on how we shifted from using 8.3 to 16.5 MeV protons for DPW and give some examples of micro-optical and micro-mechanical components recently fabricated through DPW, targeting applications in optical interconnections and in optofluidics.

Rapid prototyping of interfacing microcomponents for printed circuit board-level optical interconnects

NASA Astrophysics Data System (ADS)

Van Erps, Jürgen; Vervaeke, Michael; Thienpont, Hugo

2012-01-01

One of the important challenges for the deployment of the emerging breed of nanotechnology components is interfacing them with the external world, preferably accomplished with low-cost micro-optical devices. For the fabrication of this kind of micro-optical components, we make use of deep proton writing (DPW) as a generic rapid prototyping technology. DPW consists of bombarding polymer samples with swift protons, which results after chemical processing steps in high quality micro-optical components. The strength of the DPW micro-machining technology is the ability to fabricate monolithic building blocks that include micro-optical and mechanical functionalities which can be precisely integrated into more complex photonic systems. In this paper we give an overview of the process steps of the technology and we present several examples of micro-optical and micro-mechanical components, fabricated through DPW, targeting applications in printed circuit baordlevel optical interconnections. These include: high-precision 2-D fiber connectors, discrete out-of-plane coupling structures featuring high-quality 45° and curved micro-mirrors, arrays of high aspect ratio micro-pillars and backplane connectors. While DPW is clearly not a mass fabrication technique as such, one of its assets is that once the master component has been prototyped, a metal mould can be generated from the DPW master by applying electroplating. After removal of the plastic master, this metal mould can be used as a shim in a final microinjection moulding or hot embossing step. This way, the master component can be mass-produced at low cost in a wide variety of high-tech plastics.

The research progress of metrological 248nm deep ultraviolent microscope inspection device

NASA Astrophysics Data System (ADS)

Wang, Zhi-xin; Li, Qi; Gao, Si-tian; Shi, Yu-shu; Li, Wei; Li, Shi

2016-01-01

In lithography process, the precision of wafer pattern to a large extent depends on the geometric dimensioning and tolerance of photomasks when accuracy of lithography aligner is certain. Since the minimum linewidth (Critical Dimension) of the aligner exposing shrinks to a few tens of nanometers in size, one-tenth of tolerance errors in fabrication may lead to microchip function failure, so it is very important to calibrate these errors of photomasks. Among different error measurement instruments, deep ultraviolent (DUV) microscope because of its high resolution, as well as its advantages compared to scanning probe microscope restrained by measuring range and scanning electron microscope restrained by vacuum environment, makes itself the most suitable apparatus. But currently there is very few DUV microscope adopting 248nm optical system, means it can attain 80nm resolution; furthermore, there is almost no DUV microscope possessing traceable calibration capability. For these reason, the National Institute of Metrology, China is developing a metrological 248nm DUV microscope mainly consists of DUV microscopic components, PZT and air supporting stages as well as interferometer calibration framework. In DUV microscopic component, the Köhler high aperture transmit condenser, DUV splitting optical elements and PMT pinhole scanning elements are built. In PZT and air supporting stages, a novel PZT actuating flexural hinge stage nested separate X, Y direction kinematics and a friction wheel driving long range air supporting stage are researched. In interferometer framework, a heterodyne multi-pass interferometer measures XY axis translation and Z axis rotation through Zerodur mirror mounted on stage. It is expected the apparatus has the capability to calibrate one dimensional linewidths and two dimensional pitches ranging from 200nm to 50μm with expanded uncertainty below 20nm.

SPECIAL ISSUE ON OPTICAL PROCESSING OF INFORMATION: Waveguide optoelectronic components for devices used in functional processing of digital information

NASA Astrophysics Data System (ADS)

Gladkii, V. P.; Nikitin, V. A.; Prokhorov, V. P.; Yakovenko, N. A.

1995-10-01

The results are given of technologic and circuit-engineering development of planar micro-optics components made of glasses and of lithium niobate. These components are intended for devices to be used in logic—arithmetic processing of information.

Continuous angle steering of an optically- controlled phased array antenna based on differential true time delay constituted by micro-optical components.

PubMed

Wang, Jian; Hou, Peipei; Cai, Haiwen; Sun, Jianfeng; Wang, Shunan; Wang, Lijuan; Yang, Fei

2015-04-06

We propose an optically controlled phased array antenna (PAA) based on differential true time delay constructed optical beamforming network (OBFN). Differential true time delay is realized by stack integrated micro-optical components. Optically-controlled angle steering of radio frequency (RF) beams are realized and demonstrated by this configuration. Experimental results demonstrate that OBFN based PAA can accomplish RF-independent broadband beam steering without beam squint effect and can achieve continuous angle steering. In addition, multi-beams for different steering angles are acquired synchronously.

[Optical-fiber Fourier transform spectrometer].

PubMed

Liu, Yong; Li, Bao-sheng; Liu, Yan; Zhai, Yu-feng; Wang, An

2006-10-01

A novel Fourier transform spectrum analyzer based on a single mode fiber Mach-Zehnder interferometer is reported. An optical fiber Fourier transform spectrometer, with bulk optics components replaced by fiber optical components and with the moving mirror replaced by a piezoelectric element fiber stretcher was constructed. The output spectrum of a LD below threshold was measured. Experiment result agrees with that by using grating spectrum analyzer, showing the feasibility of the optic fiber Fourier transform spectrometer for practical spectrum measurement. Spectrum resolution -7 cm(-1) was obtained in our experiment. The resolution can be further improved by increasing the maximum optical path difference.

An empirical application of transaction-costs theory to organizational design characteristics.

PubMed

Williams, S

2000-01-01

The environmental uncertainty component of transaction-costs theory was used to predict the organizational structural characteristics of size (number of employees) and horizontal differentiation (number of vice presidents) using financial and management information from the COMPACT DISCLOSURE data base (which contains the most recent annual and periodic reports for more than 12,000 public companies). Organizations were categorized as low- or high-uncertainty industries according to Dess and Beard's (1984) Dynamism Scale, and net sales volume was controlled. As predicted, high-uncertainty companies had significantly higher horizontal differentiation than low-uncertainty firms, a finding that supports the transaction-costs expectation that organizations may require more departments or personnel to cope with increasing uncertainty. Surprisingly, low-uncertainty firms were found to have significantly more employees than high-uncertainty organizations, which is the opposite of what transaction-costs theory predicts. Possible explanations for this unexpected finding and further potential limitations are discussed.

Examples of measurement uncertainty evaluations in accordance with the revised GUM

NASA Astrophysics Data System (ADS)

Runje, B.; Horvatic, A.; Alar, V.; Medic, S.; Bosnjakovic, A.

2016-11-01

The paper presents examples of the evaluation of uncertainty components in accordance with the current and revised Guide to the expression of uncertainty in measurement (GUM). In accordance with the proposed revision of the GUM a Bayesian approach was conducted for both type A and type B evaluations.The law of propagation of uncertainty (LPU) and the law of propagation of distribution applied through the Monte Carlo method, (MCM) were used to evaluate associated standard uncertainties, expanded uncertainties and coverage intervals. Furthermore, the influence of the non-Gaussian dominant input quantity and asymmetric distribution of the output quantity y on the evaluation of measurement uncertainty was analyzed. In the case when the probabilistically coverage interval is not symmetric, the coverage interval for the probability P is estimated from the experimental probability density function using the Monte Carlo method. Key highlights of the proposed revision of the GUM were analyzed through a set of examples.

Optically-programmable nonlinear photonic component for dielectric-loaded plasmonic circuitry.

PubMed

Krasavin, Alexey V; Randhawa, Sukanya; Bouillard, Jean-Sebastien; Renger, Jan; Quidant, Romain; Zayats, Anatoly V

2011-12-05

We demonstrate both experimentally and numerically a compact and efficient, optically tuneable plasmonic component utilizing a surface plasmon polariton ring resonator with nonlinearity based on trans-cis isomerization in a polymer material. We observe more than 3-fold change between high and low transmission states of the device at milliwatt control powers (∼100 W/cm² by intensity), with the performance limited by switching speed of the material. Such plasmonic components can be employed in optically programmable and reconfigurable integrated photonic circuitry.

Optical fiber technology for space: challenges of development and qualification

NASA Astrophysics Data System (ADS)

Goepel, Michael

2017-11-01

Using fiber optical components and assemblies for space flight applications brings several challenges for the design and the qualification process. Good knowledge of the system and environmental requirements is needed to derive design decisions and select suitable components for the fiber optical subsystem. Furthermore, the manufacturing process and integration limitations are providing additional constraints, which have to be considered at the beginning of the design phase. Besides Commercial off the shelf (COTS) components, custom made parts are often necessary.

Self-assembly micro optical filter

NASA Astrophysics Data System (ADS)

Zhang, Ping (Cerina); Le, Kevin; Malalur-Nagaraja-Rao, Smitha; Hsu, Lun-Chen; Chiao, J.-C.

2006-01-01

Optical communication and sensor industry face critical challenges in manufacturing for system integration. Due to the assembly complexity and integration platform variety, micro optical components require costly alignment and assembly procedures, in which many required manual efforts. Consequently, self-assembly device architectures have become a great interest and could provide major advantages over the conventional optical devices. In this paper, we discussed a self-assembly integration platform for micro optical components. To demonstrate the adaptability and flexibility of the proposed optical device architectures, we chose a commercially available MEMS fabrication foundry service - MUMPs (Multi-User MEMS Process). In this work, polysilicon layers of MUMPS are used as the 3-D structural material for construction of micro component framework and actuators. However, because the polysilicon has high absorption in the visible and near infrared wavelength ranges, it is not suitable for optical interaction. To demonstrate the required optical performance, hybrid integration of materials was proposed and implemented. Organic compound materials were applied on the silicon-based framework to form the required optical interfaces. Organic compounds provide good optical transparency, flexibility to form filters or lens and inexpensive manufacturing procedures. In this paper, we have demonstrated a micro optical filter integrated with self-assembly structures. We will discuss the self-assembly mechanism, optical filter designs, fabrication issues and results.

Pinatubo Global- to Micro-Scale Evolution: A Unified Picture from Space, Air, and Ground Measurements

NASA Technical Reports Server (NTRS)

Russell, Philip B.; Livingston, J. M.; Puesche, R. F.; Pollack, J. B.; Brooks, S.; Hamill, P.; Hughes, J.; Thomason, L.; Stowe, L.; Deshler, T.;

Interplanetary navigation

NASA Technical Reports Server (NTRS)

Stuart, J. R.

1984-01-01

The evolution of NASA's planetary navigation techniques is traced, and radiometric and optical data types are described. Doppler navigation; the Deep Space Network; differenced two-way range techniques; differential very long base interferometry; and optical navigation are treated. The Doppler system enables a spacecraft in cruise at high absolute declination to be located within a total angular uncertainty of 1/4 microrad. The two-station range measurement provides a 1 microrad backup at low declinations. Optical data locate the spacecraft relative to the target to an angular accuracy of 5 microrad. Earth-based radio navigation and its less accurate but target-relative counterpart, optical navigation, thus form complementary measurement sources, which provide a powerful sensory system to produce high-precision orbit estimates.

Confronting uncertainty in wildlife management: performance of grizzly bear management.

PubMed

Artelle, Kyle A; Anderson, Sean C; Cooper, Andrew B; Paquet, Paul C; Reynolds, John D; Darimont, Chris T

2013-01-01

Scientific management of wildlife requires confronting the complexities of natural and social systems. Uncertainty poses a central problem. Whereas the importance of considering uncertainty has been widely discussed, studies of the effects of unaddressed uncertainty on real management systems have been rare. We examined the effects of outcome uncertainty and components of biological uncertainty on hunt management performance, illustrated with grizzly bears (Ursus arctos horribilis) in British Columbia, Canada. We found that both forms of uncertainty can have serious impacts on management performance. Outcome uncertainty alone--discrepancy between expected and realized mortality levels--led to excess mortality in 19% of cases (population-years) examined. Accounting for uncertainty around estimated biological parameters (i.e., biological uncertainty) revealed that excess mortality might have occurred in up to 70% of cases. We offer a general method for identifying targets for exploited species that incorporates uncertainty and maintains the probability of exceeding mortality limits below specified thresholds. Setting targets in our focal system using this method at thresholds of 25% and 5% probability of overmortality would require average target mortality reductions of 47% and 81%, respectively. Application of our transparent and generalizable framework to this or other systems could improve management performance in the presence of uncertainty.

Methods for handling uncertainty within pharmaceutical funding decisions

NASA Astrophysics Data System (ADS)

Stevenson, Matt; Tappenden, Paul; Squires, Hazel

2014-01-01

This article provides a position statement regarding decision making under uncertainty within the economic evaluation of pharmaceuticals, with a particular focus upon the National Institute for Health and Clinical Excellence context within England and Wales. This area is of importance as funding agencies have a finite budget from which to purchase a selection of competing health care interventions. The objective function generally used is that of maximising societal health with an explicit acknowledgement that there will be opportunity costs associated with purchasing a particular intervention. Three components of uncertainty are discussed within a pharmaceutical funding perspective: methodological uncertainty, parameter uncertainty and structural uncertainty, alongside a discussion of challenges that are particularly pertinent to health economic evaluation. The discipline has focused primarily on handling methodological and parameter uncertainty and a clear reference case has been developed for consistency across evaluations. However, uncertainties still remain. Less attention has been given to methods for handling structural uncertainty. The lack of adequate methods to explicitly incorporate this aspect of model development may result in the true uncertainty surrounding health care investment decisions being underestimated. Research in this area is ongoing as we review.

Recent Advances in Photonic Devices for Optical Computing and the Role of Nonlinear Optics-Part II

NASA Technical Reports Server (NTRS)

Abdeldayem, Hossin; Frazier, Donald O.; Witherow, William K.; Banks, Curtis E.; Paley, Mark S.

2007-01-01

The twentieth century has been the era of semiconductor materials and electronic technology while this millennium is expected to be the age of photonic materials and all-optical technology. Optical technology has led to countless optical devices that have become indispensable in our daily lives in storage area networks, parallel processing, optical switches, all-optical data networks, holographic storage devices, and biometric devices at airports. This chapters intends to bring some awareness to the state-of-the-art of optical technologies, which have potential for optical computing and demonstrate the role of nonlinear optics in many of these components. Our intent, in this Chapter, is to present an overview of the current status of optical computing, and a brief evaluation of the recent advances and performance of the following key components necessary to build an optical computing system: all-optical logic gates, adders, optical processors, optical storage, holographic storage, optical interconnects, spatial light modulators and optical materials.

A Comprehensive Plan for the Long-Term Calibration and Validation of Oceanic Biogeochemical Satellite Data

NASA Technical Reports Server (NTRS)

Hooker, Stanford B.; McClain, Charles R.; Mannino, Antonio

2007-01-01

The primary objective of this planning document is to establish a long-term capability and validating oceanic biogeochemical satellite data. It is a pragmatic solution to a practical problem based primarily o the lessons learned from prior satellite missions. All of the plan's elements are seen to be interdependent, so a horizontal organizational scheme is anticipated wherein the overall leadership comes from the NASA Ocean Biology and Biogeochemistry (OBB) Program Manager and the entire enterprise is split into two components of equal sature: calibration and validation plus satellite data processing. The detailed elements of the activity are based on the basic tasks of the two main components plus the current objectives of the Carbon Cycle and Ecosystems Roadmap. The former is distinguished by an internal core set of responsibilities and the latter is facilitated through an external connecting-core ring of competed or contracted activities. The core elements for the calibration and validation component include a) publish protocols and performance metrics; b) verify uncertainty budgets; c) manage the development and evaluation of instrumentation; and d) coordinate international partnerships. The core elements for the satellite data processing component are e) process and reprocess multisensor data; f) acquire, distribute, and archive data products; and g) implement new data products. Both components have shared responsibilities for initializing and temporally monitoring satellite calibration. Connecting-core elements include (but are not restricted to) atmospheric correction and characterization, standards and traceability, instrument and analysis round robins, field campaigns and vicarious calibration sites, in situ database, bio-optical algorithm (and product) validation, satellite characterization and vicarious calibration, and image processing software. The plan also includes an accountability process, creating a Calibration and Validation Team (to help manage the activity), and a discussion of issues associated with the plan's scientific focus.

Uncertainty quantification for optical model parameters

DOE PAGES

Lovell, A. E.; Nunes, F. M.; Sarich, J.; ...

2017-02-21

Although uncertainty quantification has been making its way into nuclear theory, these methods have yet to be explored in the context of reaction theory. For example, it is well known that different parameterizations of the optical potential can result in different cross sections, but these differences have not been systematically studied and quantified. The purpose of our work is to investigate the uncertainties in nuclear reactions that result from fitting a given model to elastic-scattering data, as well as to study how these uncertainties propagate to the inelastic and transfer channels. We use statistical methods to determine a best fitmore » and create corresponding 95% confidence bands. A simple model of the process is fit to elastic-scattering data and used to predict either inelastic or transfer cross sections. In this initial work, we assume that our model is correct, and the only uncertainties come from the variation of the fit parameters. Here, we study a number of reactions involving neutron and deuteron projectiles with energies in the range of 5–25 MeV/u, on targets with mass A=12–208. We investigate the correlations between the parameters in the fit. The case of deuterons on 12C is discussed in detail: the elastic-scattering fit and the prediction of 12C(d,p) 13C transfer angular distributions, using both uncorrelated and correlated χ 2 minimization functions. The general features for all cases are compiled in a systematic manner to identify trends. This work shows that, in many cases, the correlated χ 2 functions (in comparison to the uncorrelated χ 2 functions) provide a more natural parameterization of the process. These correlated functions do, however, produce broader confidence bands. Further optimization may require improvement in the models themselves and/or more information included in the fit.« less

Uncertainties in Cloud Phase and Optical Thickness Retrievals from the Earth Polychromatic Imaging Camera (EPIC)

NASA Technical Reports Server (NTRS)

Meyer, Kerry; Yang, Yuekui; Platnick, Steven

2016-01-01

This paper presents an investigation of the expected uncertainties of a single channel cloud optical thickness (COT) retrieval technique, as well as a simple cloud-temperature-threshold-based thermodynamic phase approach, in support of the Deep Space Climate Observatory (DSCOVR) mission. DSCOVR cloud products will be derived from Earth Polychromatic Imaging Camera (EPIC) observations in the ultraviolet and visible spectra. Since EPIC is not equipped with a spectral channel in the shortwave or mid-wave infrared that is sensitive to cloud effective radius (CER), COT will be inferred from a single visible channel with the assumption of appropriate CER values for liquid and ice phase clouds. One month of Aqua MODIS daytime granules from April 2005 is selected for investigating cloud phase sensitivity, and a subset of these granules that has similar EPIC sun-view geometry is selected for investigating COT uncertainties. EPIC COT retrievals are simulated with the same algorithm as the operational MODIS cloud products (MOD06), except using fixed phase-dependent CER values. Uncertainty estimates are derived by comparing the single channel COT retrievals with the baseline bi-spectral MODIS retrievals. Results show that a single channel COT retrieval is feasible for EPIC. For ice clouds, single channel retrieval errors are minimal (less than 2 percent) due to the particle- size insensitivity of the assumed ice crystal (i.e., severely roughened aggregate of hexagonal columns) scattering properties at visible wavelengths, while for liquid clouds the error is mostly limited to within 10 percent, although for thin clouds (COT less than 2) the error can be higher. Potential uncertainties in EPIC cloud masking and cloud temperature retrievals are not considered in this study.

Uncertainties in cloud phase and optical thickness retrievals from the Earth Polychromatic Imaging Camera (EPIC)

PubMed Central

Meyer, Kerry; Yang, Yuekui; Platnick, Steven

2018-01-01

This paper presents an investigation of the expected uncertainties of a single channel cloud optical thickness (COT) retrieval technique, as well as a simple cloud temperature threshold based thermodynamic phase approach, in support of the Deep Space Climate Observatory (DSCOVR) mission. DSCOVR cloud products will be derived from Earth Polychromatic Imaging Camera (EPIC) observations in the ultraviolet and visible spectra. Since EPIC is not equipped with a spectral channel in the shortwave or mid-wave infrared that is sensitive to cloud effective radius (CER), COT will be inferred from a single visible channel with the assumption of appropriate CER values for liquid and ice phase clouds. One month of Aqua MODIS daytime granules from April 2005 is selected for investigating cloud phase sensitivity, and a subset of these granules that has similar EPIC sun-view geometry is selected for investigating COT uncertainties. EPIC COT retrievals are simulated with the same algorithm as the operational MODIS cloud products (MOD06), except using fixed phase-dependent CER values. Uncertainty estimates are derived by comparing the single channel COT retrievals with the baseline bi-spectral MODIS retrievals. Results show that a single channel COT retrieval is feasible for EPIC. For ice clouds, single channel retrieval errors are minimal (< 2%) due to the particle size insensitivity of the assumed ice crystal (i.e., severely roughened aggregate of hexagonal columns) scattering properties at visible wavelengths, while for liquid clouds the error is mostly limited to within 10%, although for thin clouds (COT < 2) the error can be higher. Potential uncertainties in EPIC cloud masking and cloud temperature retrievals are not considered in this study. PMID:29619116

Comparison of model estimated and measured direct-normal solar irradiance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Halthore, R.N.; Schwartz, S.E.; Michalsky, J.J.

1997-12-01

Direct-normal solar irradiance (DNSI), the energy in the solar spectrum incident in unit time at the Earth{close_quote}s surface on a unit area perpendicular to the direction to the Sun, depends only on atmospheric extinction of solar energy without regard to the details of the extinction, whether absorption or scattering. Here we report a set of closure experiments performed in north central Oklahoma in April 1996 under cloud-free conditions, wherein measured atmospheric composition and aerosol optical thickness are input to a radiative transfer model, MODTRAN 3, to estimate DNSI, which is then compared with measured values obtained with normal incidence pyrheliometersmore » and absolute cavity radiometers. Uncertainty in aerosol optical thickness (AOT) dominates the uncertainty in DNSI calculation. AOT measured by an independently calibrated Sun photometer and a rotating shadow-band radiometer agree to within the uncertainties of each measurement. For 36 independent comparisons the agreement between measured and model-estimated values of DNSI falls within the combined uncertainties in the measurement (0.3{endash}0.7{percent}) and model calculation (1.8{percent}), albeit with a slight average model underestimate ({minus}0.18{plus_minus}0.94){percent}; for a DNSI of 839Wm{sup {minus}2} this corresponds to {minus}1.5{plus_minus}7.9Wm{sup {minus}2}. The agreement is nearly independent of air mass and water-vapor path abundance. These results thus establish the accuracy of the current knowledge of the solar spectrum, its integrated power, and the atmospheric extinction as a function of wavelength as represented in MODTRAN 3. An important consequence is that atmospheric absorption of short-wave energy is accurately parametrized in the model to within the above uncertainties. {copyright} 1997 American Geophysical Union« less

Uncertainties in cloud phase and optical thickness retrievals from the Earth Polychromatic Imaging Camera (EPIC).

PubMed

Meyer, Kerry; Yang, Yuekui; Platnick, Steven

2016-01-01

This paper presents an investigation of the expected uncertainties of a single channel cloud optical thickness (COT) retrieval technique, as well as a simple cloud temperature threshold based thermodynamic phase approach, in support of the Deep Space Climate Observatory (DSCOVR) mission. DSCOVR cloud products will be derived from Earth Polychromatic Imaging Camera (EPIC) observations in the ultraviolet and visible spectra. Since EPIC is not equipped with a spectral channel in the shortwave or mid-wave infrared that is sensitive to cloud effective radius (CER), COT will be inferred from a single visible channel with the assumption of appropriate CER values for liquid and ice phase clouds. One month of Aqua MODIS daytime granules from April 2005 is selected for investigating cloud phase sensitivity, and a subset of these granules that has similar EPIC sun-view geometry is selected for investigating COT uncertainties. EPIC COT retrievals are simulated with the same algorithm as the operational MODIS cloud products (MOD06), except using fixed phase-dependent CER values. Uncertainty estimates are derived by comparing the single channel COT retrievals with the baseline bi-spectral MODIS retrievals. Results show that a single channel COT retrieval is feasible for EPIC. For ice clouds, single channel retrieval errors are minimal (< 2%) due to the particle size insensitivity of the assumed ice crystal (i.e., severely roughened aggregate of hexagonal columns) scattering properties at visible wavelengths, while for liquid clouds the error is mostly limited to within 10%, although for thin clouds (COT < 2) the error can be higher. Potential uncertainties in EPIC cloud masking and cloud temperature retrievals are not considered in this study.

Geodetic methods to determine the relativistic redshift at the level of 10^{-18} in the context of international timescales: a review and practical results

NASA Astrophysics Data System (ADS)

Denker, Heiner; Timmen, Ludger; Voigt, Christian; Weyers, Stefan; Peik, Ekkehard; Margolis, Helen S.; Delva, Pacôme; Wolf, Peter; Petit, Gérard

2017-12-01

The frequency stability and uncertainty of the latest generation of optical atomic clocks is now approaching the one part in 10^{18} level. Comparisons between earthbound clocks at rest must account for the relativistic redshift of the clock frequencies, which is proportional to the corresponding gravity (gravitational plus centrifugal) potential difference. For contributions to international timescales, the relativistic redshift correction must be computed with respect to a conventional zero potential value in order to be consistent with the definition of Terrestrial Time. To benefit fully from the uncertainty of the optical clocks, the gravity potential must be determined with an accuracy of about 0.1 m2 s^{-2} , equivalent to about 0.01 m in height. This contribution focuses on the static part of the gravity field, assuming that temporal variations are accounted for separately by appropriate reductions. Two geodetic approaches are investigated for the derivation of gravity potential values: geometric levelling and the Global Navigation Satellite Systems (GNSS)/geoid approach. Geometric levelling gives potential differences with millimetre uncertainty over shorter distances (several kilometres), but is susceptible to systematic errors at the decimetre level over large distances. The GNSS/geoid approach gives absolute gravity potential values, but with an uncertainty corresponding to about 2 cm in height. For large distances, the GNSS/geoid approach should therefore be better than geometric levelling. This is demonstrated by the results from practical investigations related to three clock sites in Germany and one in France. The estimated uncertainty for the relativistic redshift correction at each site is about 2 × 10^{-18}.

Retrieval of Ice Cloud Properties Using an Optimal Estimation Algorithm and MODIS Infrared Observations: 2. Retrieval Evaluation

NASA Technical Reports Server (NTRS)

Wang, Chenxi; Platnick, Steven; Zhang, Zhibo; Meyer, Kerry; Wind, Galina; Yang, Ping

2016-01-01

An infrared-based optimal estimation (OE-IR) algorithm for retrieving ice cloud properties is evaluated. Specifically, the implementation of the algorithm with MODerate resolution Imaging Spectroradiometer (MODIS) observations is assessed in comparison with the operational retrieval products from MODIS on the Aqua satellite (MYD06), Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), and the Imaging Infrared Radiometer (IIR); the latter two instruments fly on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite in the Afternoon Constellation (A-Train) with Aqua. The results show that OE-IR cloud optical thickness (tau) and effective radius (r(sub eff)) retrievals perform best for ice clouds having 0.5 < tau< 7 and r(sub eff) < 50microns. For global ice clouds, the averaged retrieval uncertainties of tau and r(sub eff) are 19% and 33%, respectively. For optically thick ice clouds with tau larger than 10, however, the tau and r(sub eff) retrieval uncertainties can exceed 30% and 50%, respectively. For ice cloud top height (h), the averaged global uncertainty is 0.48km. Relatively large h uncertainty (e.g., > 1km) occurs for tau < 0.5. Analysis of 1month of the OE-IR retrievals shows large tau and r(sub eff) uncertainties in storm track regions and the southern oceans where convective clouds are frequently observed, as well as in high-latitude regions where temperature differences between the surface and cloud top are more ambiguous. Generally, comparisons between the OE-IR and the operational products show consistent tau and h retrievals. However, obvious differences between the OE-IR and the MODIS Collection 6 r(sub eff) are found.

Uncertainties in cloud phase and optical thickness retrievals from the Earth Polychromatic Imaging Camera (EPIC)

NASA Astrophysics Data System (ADS)

Meyer, Kerry; Yang, Yuekui; Platnick, Steven

2016-04-01

This paper presents an investigation of the expected uncertainties of a single-channel cloud optical thickness (COT) retrieval technique, as well as a simple cloud-temperature-threshold-based thermodynamic phase approach, in support of the Deep Space Climate Observatory (DSCOVR) mission. DSCOVR cloud products will be derived from Earth Polychromatic Imaging Camera (EPIC) observations in the ultraviolet and visible spectra. Since EPIC is not equipped with a spectral channel in the shortwave or mid-wave infrared that is sensitive to cloud effective radius (CER), COT will be inferred from a single visible channel with the assumption of appropriate CER values for liquid and ice phase clouds. One month of Aqua MODerate-resolution Imaging Spectroradiometer (MODIS) daytime granules from April 2005 is selected for investigating cloud phase sensitivity, and a subset of these granules that has similar EPIC Sun-view geometry is selected for investigating COT uncertainties. EPIC COT retrievals are simulated with the same algorithm as the operational MODIS cloud products (MOD06), except using fixed phase-dependent CER values. Uncertainty estimates are derived by comparing the single-channel COT retrievals with the baseline bi-spectral MODIS retrievals. Results show that a single-channel COT retrieval is feasible for EPIC. For ice clouds, single-channel retrieval errors are minimal (< 2 %) due to the particle size insensitivity of the assumed ice crystal (i.e., severely roughened aggregate of hexagonal columns) scattering properties at visible wavelengths, while for liquid clouds the error is mostly limited to within 10 %, although for thin clouds (COT < 2) the error can be higher. Potential uncertainties in EPIC cloud masking and cloud temperature retrievals are not considered in this study.

The development of a cryogenic integrated system with the working temperature of 100K

NASA Astrophysics Data System (ADS)

Liu, En'guang; Wu, Yi'nong; Wang, Yueming; Wen, Jiajia; Lv, Gang; Li, Chunlai; Hou, Jia; Yuan, Liyin

2016-05-01

In the infrared system, cooling down the optic components' temperature is a better choice to decrease the background radiation and maximize the sensitivity. This paper presented a 100K cryogenic optical system, for which an integrated designation of mechanical cooler, flexible thermal link and optical bench was developed. The whole infrared optic components which were assembled in a vacuum box were cooled down to 100K by two mechanical coolers. Low thermal conductivity supports and low emissivity multi-layers were used to reduce the cryogenic optical system's heat loss. The experiment results showed that in about eight hours, the temperature of the optical components reached 100K from room temperature, and the vibration from the mechanical coolers nearly have no affection to the imaging process by using of thermal links. Some experimental results of this cryogenic system will be discussed in this paper.

On the characterization of ultra-precise X-ray optical components: advances and challenges in ex situ metrology

PubMed Central

Siewert, F.; Buchheim, J.; Zeschke, T.; Störmer, M.; Falkenberg, G.; Sankari, R.

2014-01-01

To fully exploit the ultimate source properties of the next-generation light sources, such as free-electron lasers (FELs) and diffraction-limited storage rings (DLSRs), the quality requirements for gratings and reflective synchrotron optics, especially mirrors, have significantly increased. These coherence-preserving optical components for high-brightness sources will feature nanoscopic shape accuracies over macroscopic length scales up to 1000 mm. To enable high efficiency in terms of photon flux, such optics will be coated with application-tailored single or multilayer coatings. Advanced thin-film fabrication of today enables the synthesis of layers on the sub-nanometre precision level over a deposition length of up to 1500 mm. Specifically dedicated metrology instrumentation of comparable accuracy has been developed to characterize such optical elements. Second-generation slope-measuring profilers like the nanometre optical component measuring machine (NOM) at the BESSY-II Optics laboratory allow the inspection of up to 1500 mm-long reflective optical components with an accuracy better than 50 nrad r.m.s. Besides measuring the shape on top of the coated mirror, it is of particular interest to characterize the internal material properties of the mirror coating, which is the domain of X-rays. Layer thickness, density and interface roughness of single and multilayer coatings are investigated by means of X-ray reflectometry. In this publication recent achievements in the field of slope measuring metrology are shown and the characterization of different types of mirror coating demonstrated. Furthermore, upcoming challenges to the inspection of ultra-precise optical components designed to be used in future FEL and DLSR beamlines are discussed. PMID:25177985

Aerosol Direct Radiative Effects Over the Northwest Atlantic, Northwest Pacific, and North Indian Oceans: Estimates Based on In-situ Chemical and Optical Measurements and Chemical Transport Modeling

NASA Astrophysics Data System (ADS)

Bates, T. S.; Anderson, T. L.; Baynard, T.; Bond, T.; Boucher, O.; Carmichael, G.; Clarke, A.; Erlick, C.; Guo, H.; Horowitz, L.; Howell, S.; Kulkarni, S.; Maring, H.; McComiskey, A.; Middlebrook, A.; Noone, K.; O'Dowd, C. D.; Ogren, J. A.; Penner, J.; Quinn, P. K.; Ravishankara, A. R.; Savoie, D. L.; Schwartz, S. E.; Shinozuka, Y.; Tang, Y.; Weber, R. J.; Wu, Y.

2005-12-01

The largest uncertainty in the radiative forcing of climate change over the industrial era is that due to aerosols, a substantial fraction of which is the uncertainty associated with scattering and absorption of shortwave (solar) radiation by anthropogenic aerosols in cloud-free conditions. Quantifying and reducing the uncertainty in aerosol influences on climate is critical to understanding climate change over the industrial period and to improving predictions of future climate change for assumed emission scenarios. Measurements of aerosol properties during major field campaigns in several regions of the globe during the past decade are contributing to an enhanced understanding of atmospheric aerosols and their effects on light scattering and climate. The present study, which focuses on three regions downwind of major urban/population centers (North Indian Ocean during INDOEX, the Northwest Pacific Ocean during ACE-Asia, and the Northwest Atlantic Ocean during ICARTT), incorporates understanding gained from field observations of aerosol distributions and properties into calculations of perturbations in radiative fluxes due to these aerosols. This study evaluates the current state of observations and of two chemical transport models (STEM and MOZART). Measurements of burdens, extinction optical depth, and direct radiative effect of aerosols (change in radiative flux due to total aerosols) are used as measurement-model check points to assess uncertainties. In-situ measured and remotely sensed aerosol properties for each region (mixing state, mass scattering efficiency, single scattering albedo, and angular scattering properties and their dependences on relative humidity) are used as input parameters to two radiative transfer models (GFDL and University of Michigan) to constrain estimates of aerosol radiative effects, with uncertainties in each step propagated through the analysis. Such comparisons with observations and resultant reductions in uncertainties are essential for improving and developing confidence in climate model calculations incorporating aerosol forcing.

Measuring the In-Process Figure, Final Prescription, and System Alignment of Large Optics and Segmented Mirrors Using Lidar Metrology

NASA Technical Reports Server (NTRS)

Ohl, Raymond; Slotwinski, Anthony; Eegholm, Bente; Saif, Babak

2011-01-01

The fabrication of large optics is traditionally a slow process, and fabrication capability is often limited by measurement capability. W hile techniques exist to measure mirror figure with nanometer precis ion, measurements of large-mirror prescription are typically limited to submillimeter accuracy. Using a lidar instrument enables one to measure the optical surface rough figure and prescription in virtuall y all phases of fabrication without moving the mirror from its polis hing setup. This technology improves the uncertainty of mirror presc ription measurement to the micron-regime.

Terminal navigation analysis for the 1980 comet Encke slow flyby mission

NASA Technical Reports Server (NTRS)

Jacobson, R. A.; Mcdanell, J. P.; Rinker, G. C.

1973-01-01

The initial results of a terminal navigation analysis for the proposed 1980 solar electric slow flyby mission to the comet Encke are presented. The navigation technique employs onboard optical measurements with the scientific television camera, groundbased observations of the spacecraft and comet, and groundbased orbit determination and thrust vector update computation. The knowledge and delivery accuracies of the spacecraft are evaluated as a function of the important parameters affecting the terminal navigation. These include optical measurement accuracy, thruster noise level, duration of the planned terminal coast period, comet ephemeris uncertainty, guidance initiation time, guidance update frequency, and optical data rate.

Optimality based repetitive controller design for track-following servo system of optical disk drives.

PubMed

Chen, Wentao; Zhang, Weidong

2009-10-01

In an optical disk drive servo system, to attenuate the external periodic disturbances induced by inevitable disk eccentricity, repetitive control has been used successfully. The performance of a repetitive controller greatly depends on the bandwidth of the low-pass filter included in the repetitive controller. However, owing to the plant uncertainty and system stability, it is difficult to maximize the bandwidth of the low-pass filter. In this paper, we propose an optimality based repetitive controller design method for the track-following servo system with norm-bounded uncertainties. By embedding a lead compensator in the repetitive controller, both the system gain at periodic signal's harmonics and the bandwidth of the low-pass filter are greatly increased. The optimal values of the repetitive controller's parameters are obtained by solving two optimization problems. Simulation and experimental results are provided to illustrate the effectiveness of the proposed method.

Investigation of the interpolation method to improve the distributed strain measurement accuracy in optical frequency domain reflectometry systems.

PubMed

Cui, Jiwen; Zhao, Shiyuan; Yang, Di; Ding, Zhenyang

2018-02-20

We use a spectrum interpolation technique to improve the distributed strain measurement accuracy in a Rayleigh-scatter-based optical frequency domain reflectometry sensing system. We demonstrate that strain accuracy is not limited by the "uncertainty principle" that exists in the time-frequency analysis. Different interpolation methods are investigated and used to improve the accuracy of peak position of the cross-correlation and, therefore, improve the accuracy of the strain. Interpolation implemented by padding zeros on one side of the windowed data in the spatial domain, before the inverse fast Fourier transform, is found to have the best accuracy. Using this method, the strain accuracy and resolution are both improved without decreasing the spatial resolution. The strain of 3 μϵ within the spatial resolution of 1 cm at the position of 21.4 m is distinguished, and the measurement uncertainty is 3.3 μϵ.

Aerosol Sources, Absorption, and Intercontinental Transport: Synergies among Models, Remote Sensing, and Atmospheric Measurements

NASA Technical Reports Server (NTRS)

Chin, Mian; Ginoux, Paul; Dubovik, Oleg; Holben, Brent; Kaufman, Yoram; chu, Allen; Anderson, Tad; Quinn, Patricia

2003-01-01

Aerosol climate forcing is one of the largest uncertainties in assessing the anthropogenic impact on the global climate system. This uncertainty arises from the poorly quantified aerosol sources, especially black carbon emissions, our limited knowledge of aerosol mixing state and optical properties, and the consequences of intercontinental transport of aerosols and their precursors. Here we use a global model GOCART to simulate atmospheric aerosols, including sulfate, black carbon, organic carbon, dust, and sea salt, from anthropogenic, biomass burning, and natural sources. We compare the model calculated aerosol extinction and absorption with those quantities from the ground-based sun photometer measurements from AERONET at several different wavelengths and the field observations from ACE-Asia, and model calculated total aerosol optical depth and fine mode fractions with the MODIS satellite retrieval. We will also estimate the intercontinental transport of pollution and dust aerosols from their source regions to other areas in different seasons.

Aerosol Sources, Absorption, and Intercontinental Transport: Synergies Among Models, Remote Sensing, and Atmospheric Measurements

NASA Technical Reports Server (NTRS)

Chin, Mian; Chu, Allen; Levy, Robert; Remer, Lorraine; Kaufman, Yoram; Dubovik, Oleg; Holben, Brent; Eck, Tom; Anderson, Tad; Quinn, Patricia

2004-01-01

Aerosol climate forcing is one of the largest uncertainties in assessing the anthropogenic impact on the global climate system. This uncertainty arises from the poorly quantified aerosol sources, especially black carbon emissions, our limited knowledge of aerosol mixing state and optical properties, and the consequences of intercontinental transport of aerosols and their precursors. Here we use a global model GOCART to simulate atmospheric aerosols, including sulfate, black carbon, organic carbon, dust, and sea salt, from anthropogenic, .biomass burning, and natural sources. We compare the model calculated aerosol extinction and absorption with those quantities from the ground-based sun photometer measurements from AERON" at several different wavelengths and the field observations from ACE-Asia, and model calculated total aerosol optical depth and fine mode fractions with the MODIS satellite retrieval. We will also estimate the intercontinental transport of pollution and dust aerosols from their source regions to other areas in different seasons.

Implications of Satellite Swath Width on Global Aerosol Optical Thickness Statistics

NASA Technical Reports Server (NTRS)

Colarco, Peter; Kahn, Ralph; Remer, Lorraine; Levy, Robert; Welton, Ellsworth

2012-01-01

We assess the impact of swath width on the statistics of aerosol optical thickness (AOT) retrieved by satellite as inferred from observations made by the Moderate Resolution Imaging Spectroradiometer (MODIS). We sub-sample the year 2009 MODIS data from both the Terra and Aqua spacecraft along several candidate swaths of various widths. We find that due to spatial sampling there is an uncertainty of approximately 0.01 in the global, annual mean AOT. The sub-sampled monthly mean gridded AOT are within +/- 0.01 of the full swath AOT about 20% of the time for the narrow swath sub-samples, about 30% of the time for the moderate width sub-samples, and about 45% of the time for the widest swath considered. These results suggest that future aerosol satellite missions with only a narrow swath view may not sample the true AOT distribution sufficiently to reduce significantly the uncertainty in aerosol direct forcing of climate.

A statistical method for determining the dimensions, tolerances and specification of optics for the Laser Megajoule facility (LMJ)

NASA Astrophysics Data System (ADS)

Denis, Vincent

2008-09-01

This paper presents a statistical method for determining the dimensions, tolerance and specifications of components for the Laser MegaJoule (LMJ). Numerous constraints inherent to a large facility require specific tolerances: the huge number of optical components; the interdependence of these components between the beams of same bundle; angular multiplexing for the amplifier section; distinct operating modes between the alignment and firing phases; the definition and use of alignment software in the place of classic optimization. This method provides greater flexibility to determine the positioning and manufacturing specifications of the optical components. Given the enormous power of the Laser MegaJoule (over 18 kJ in the infrared and 9 kJ in the ultraviolet), one of the major risks is damage the optical mounts and pollution of the installation by mechanical ablation. This method enables estimation of the beam occultation probabilities and quantification of the risks for the facility. All the simulations were run using the ZEMAX-EE optical design software.

Analysis of near-field components of a plasmonic optical antenna and their contribution to quantum dot infrared photodetector enhancement.

PubMed

Gu, Guiru; Vaillancourt, Jarrod; Lu, Xuejun

2014-10-20

In this paper, we analyze near-field vector components of a metallic circular disk array (MCDA) plasmonic optical antenna and their contribution to quantum dot infrared photodetector (QDIP) enhancement. The near-field vector components of the MCDA optical antenna and their distribution in the QD active region are simulated. The near-field overlap integral with the QD active region is calculated at different wavelengths and compared with the QDIP enhancement spectrum. The x-component (E(x)) of the near-field vector shows a larger intensity overlap integral and stronger correlation with the QDIP enhancement than E(z) and thus is determined to be the major near-field component to the QDIP enhancement.

Self-reverse-biased solar panel optical receiver for simultaneous visible light communication and energy harvesting.

PubMed

Shin, Won-Ho; Yang, Se-Hoon; Kwon, Do-Hoon; Han, Sang-Kook

2016-10-31

We propose a self-reverse-biased solar panel optical receiver for energy harvesting and visible light communication. Since the solar panel converts an optical component into an electrical component, it provides both energy harvesting and communication. The signal component can be separated from the direct current component, and these components are used for communication and energy harvesting. We employed a self-reverse-biased receiver circuit to improve the communication and energy harvesting performance. The reverse bias on the solar panel improves the responsivity and response time. The proposed system achieved 17.05 mbps discrete multitone transmission with a bit error rate of 1.1 x 10^-3 and enhanced solar energy conversion efficiency.

Optical-frequency transfer over a single-span 1840 km fiber link.

PubMed

Droste, S; Ozimek, F; Udem, Th; Predehl, K; Hänsch, T W; Schnatz, H; Grosche, G; Holzwarth, R

2013-09-13

To compare the increasing number of optical frequency standards, highly stable optical signals have to be transferred over continental distances. We demonstrate optical-frequency transfer over a 1840-km underground optical fiber link using a single-span stabilization. The low inherent noise introduced by the fiber allows us to reach short term instabilities expressed as the modified Allan deviation of 2×10(-15) for a gate time τ of 1 s reaching 4×10(-19) in just 100 s. We find no systematic offset between the sent and transferred frequencies within the statistical uncertainty of about 3×10(-19). The spectral noise distribution of our fiber link at low Fourier frequencies leads to a τ(-2) slope in the modified Allan deviation, which is also derived theoretically.

Quantifying and Reducing Uncertainty in Correlated Multi-Area Short-Term Load Forecasting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Yannan; Hou, Zhangshuan; Meng, Da

2016-07-17

In this study, we represent and reduce the uncertainties in short-term electric load forecasting by integrating time series analysis tools including ARIMA modeling, sequential Gaussian simulation, and principal component analysis. The approaches are mainly focusing on maintaining the inter-dependency between multiple geographically related areas. These approaches are applied onto cross-correlated load time series as well as their forecast errors. Multiple short-term prediction realizations are then generated from the reduced uncertainty ranges, which are useful for power system risk analyses.

Physical effects involved in the measurements of neutrino masses with future cosmological data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Archidiacono, Maria; Brinckmann, Thejs; Lesgourgues, Julien

Future Cosmic Microwave Background experiments together with upcoming galaxy and 21-cm surveys will provide extremely accurate measurements of different cosmological observables located at different epochs of the cosmic history. The new data will be able to constrain the neutrino mass sum with the best precision ever. In order to exploit the complementarity of the different redshift probes, a deep understanding of the physical effects driving the impact of massive neutrinos on CMB and large scale structures is required. The goal of this work is to describe these effects, assuming a summed neutrino mass close to its minimum allowed value. Wemore » find that parameter degeneracies can be removed by appropriate combinations, leading to robust and model independent constraints. A joint forecast of the sensitivity of Euclid and DESI surveys together with a CORE-like CMB experiment leads to a 1σ uncertainty of 14 meV on the summed neutrino mass. Finally the degeneracy between M {sub ν} and the optical depth at reionization τ{sub reio}, originating in the combination of CMB and low redshift galaxy probes, might be broken by future 21-cm surveys, thus further decreasing the uncertainty on M {sub ν}. For instance, an independent determination of the optical depth with an accuracy of σ(τ{sub reio})=0.001 (which might be achievable, although this is subject to astrophysical uncertainties) would decrease the uncertainty down to σ( M {sub ν})=12 meV.« less

Forest Management Under Uncertainty for Multiple Bird Population Objectives

Treesearch

Clinton T. Moore; W. Todd Plummer; Michael J. Conroy

2005-01-01

We advocate adaptive programs of decision making and monitoring for the management of forest birds when responses by populations to management, and particularly management trade-offs among populations, are uncertain. Models are necessary components of adaptive management. Under this approach, uncertainty about the behavior of a managed system is explicitly captured in...

Method for Balancing Detector Output to a Desired Level of Balance at a Frequency

NASA Technical Reports Server (NTRS)

Sachse, Glenn W. (Inventor)

2003-01-01

A multi-gas sensor is provided which modulates a polarized light beam over a broadband of wavelengths between two alternating orthogonal polarization components. The two orthogonal polarization components of the polarization modulated beam are directed along two distinct optical paths. At least one optical path contains one or more spectral discrimination elements, with each spectral discrimination element having spectral absorption features of one or more gases of interest being measured. The two optical paths then intersect, and one orthogonal component of the intersected components is transmitted and the other orthogonal component is reflected. The combined polarization modulated beam is partitioned into one or more smaller spectral regions of interest where one or more gases of interest has an absorption band. The difference in intensity between the two orthogonal polarization components is then determined in each partitioned spectral region of interest as an indication of the spectral emission/absorption of the light beam by the gases of interest in the measurement path. The spectral emission/absorption is indicative of the concentration of the one or more gases of interest in the measurement path. More specifically, one embodiment of the present invention is a gas filter correlation radiometer which comprises a polarizer, a polarization modulator, a polarization beam splitter, a beam combiner, wavelength partitioning element, and detection element. The gases of interest are measured simultaneously and, further, can be measured independently or non-independently. Furthermore, optical or electronic element are provided to balance optical intensities between the two optical paths.

Multi-Gas Sensor

NASA Technical Reports Server (NTRS)

Sachse, Glenn W. (Inventor); Wang, Liang-Guo (Inventor); LeBel, Peter J. (Inventor); Steele, Tommy C. (Inventor); Rana, Mauro (Inventor)

1999-01-01

A multi-gas sensor is provided which modulates a polarized light beam over a broadband of wavelengths between two alternating orthogonal polarization components. The two orthogonal polarization components of the polarization modulated beam are directed along two distinct optical paths. At least one optical path contains one or more spectral discrimination element, with each spectral discrimination element having spectral absorption features of one or more gases of interest being measured. The two optical paths then intersect, and one orthogonal component of the intersected components is transmitted and the other orthogonal component is reflected. The combined polarization modulated beam is partitioned into one or more smaller spectral regions of interest where one or more gases of interest has an absorption band. The difference in intensity between the two orthogonal polarization components is then determined in each partitioned spectral region of interest as an indication of the spectral emission/absorption of the light beam by the gases of interest in the measurement path. The spectral emission/absorption is indicative of the concentration of the one or more gases of interest in the measurement path. More specifically, one embodiment of the present invention is a gas filter correlation radiometer which comprises a polarizer, a polarization modulator, a polarization beam splitter, a beam combiner, wavelength partitioning element, and detection element. The gases of interest are measured simultaneously and, further, can be measured independently or non-independently. Furthermore, optical or electronic element are provided to balance optical intensities between the two optical paths.

Simulation studies on the effect of positioning tolerances on optical coupling efficiency

NASA Astrophysics Data System (ADS)

Pamidighantam, Ramana V.; Yeo, Yongkee; Sudharsanam, Krishnamachari; Lee, Sik Pong; Iyer, Mahadevan K.

2002-08-01

The development of Optoelectronic components for communications is converging towards access networks where device cost makes a significant impact on the market acceptance. Thus, the device design engineer needs to input assembly, fabrication and process constraints into the design at an early stage. The present study is part of a Project on Packaging of Optical Components that IME, Singapore has initiated as part of an ongoing Electronics Packaging Research Consortium with industry partnership. In the present study, the coupling of optical radiation from a laser diode to optical fiber is simulated for a fiber optic transmitter component development project. Different optical configurations based on direct coupling, spherical ball lenses, integral lensed fibers and thermally expanded fibers are created within the commercially available transmitter package space. The effect of optical element variables on the placement tolerance is analyzed and will be reported. The effect of alignment tolerances on the optical coupling is analyzed. Simulation results are presented recommending realizable alignment and placement tolerances to develop a low cost short range link distance transmitter.

Cantilever spring constant calibration using laser Doppler vibrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ohler, Benjamin

2007-06-15

Uncertainty in cantilever spring constants is a critical issue in atomic force microscopy (AFM) force measurements. Though numerous methods exist for calibrating cantilever spring constants, the accuracy of these methods can be limited by both the physical models themselves as well as uncertainties in their experimental implementation. Here we report the results from two of the most common calibration methods, the thermal tune method and the Sader method. These were implemented on a standard AFM system as well as using laser Doppler vibrometry (LDV). Using LDV eliminates some uncertainties associated with optical lever detection on an AFM. It also offersmore » considerably higher signal to noise deflection measurements. We find that AFM and LDV result in similar uncertainty in the calibrated spring constants, about 5%, using either the thermal tune or Sader methods provided that certain limitations of the methods and instrumentation are observed.« less

Evaluation of the Long-Term Stability and Temperature Coefficient of Dew-Point Hygrometers

NASA Astrophysics Data System (ADS)

Benyon, R.; Vicente, T.; Hernández, P.; De Rivas, L.; Conde, F.

2012-09-01

The continuous quest for improved specifications of optical dew-point hygrometers has raised customer expectations on the performance of these devices. In the absence of a long calibration history, users with a limited prior experience in the measurement of humidity, place reliance on manufacturer specifications to estimate long-term stability. While this might be reasonable in the case of measurement of electrical quantities, in humidity it can lead to optimistic estimations of uncertainty. This article reports a study of the long-term stability of some hygrometers and the analysis of their performance as monitored through regular calibration. The results of the investigations provide some typical, realistic uncertainties associated with the long-term stability of instruments used in calibration and testing laboratories. Together, these uncertainties can help in establishing initial contributions in uncertainty budgets, as well as in setting the minimum calibration requirements, based on the evaluation of dominant influence quantities.

White-Light Phase-Conjugate Mirrors as Distortion Correctors

NASA Technical Reports Server (NTRS)

Frazier, Donald; Smith, W. Scott; Abdeldayem, Hossin; Banerjee, Partha

2010-01-01

White-light phase-conjugate mirrors would be incorporated into some optical systems, according to a proposal, as means of correcting for wavefront distortions caused by imperfections in large optical components. The proposal was given impetus by a recent demonstration that white, incoherent light can be made to undergo phase conjugation, whereas previously, only coherent light was known to undergo phase conjugation. This proposal, which is potentially applicable to almost any optical system, was motivated by a need to correct optical aberrations of the primary mirror of the Hubble Space telescope. It is difficult to fabricate large optical components like the Hubble primary mirror and to ensure the high precision typically required of such components. In most cases, despite best efforts, the components as fabricated have small imperfections that introduce optical aberrations that adversely affect imaging quality. Correcting for such aberrations is difficult and costly. The proposed use of white-light phase conjugate mirrors offers a relatively simple and inexpensive solution of the aberration-correction problem. Indeed, it should be possible to simplify the entire approach to making large optical components because there would be no need to fabricate those components with extremely high precision in the first place: A white-light phase-conjugate mirror could correct for all the distortions and aberrations in an optical system. The use of white-light phase-conjugate mirrors would be essential for ensuring high performance in optical systems containing lightweight membrane mirrors, which are highly deformable. As used here, "phase-conjugate mirror" signifies, more specifically, an optical component in which incident light undergoes time-reversal phase conjugation. In practice, a phase-conjugate mirror would typically be implemented by use of a suitably positioned and oriented photorefractive crystal. In the case of a telescope comprising a primary and secondary mirror (see figure) white light from a distant source would not be brought to initial focus on one or more imaging scientific instrument(s) as in customary practice. Instead, the light would be brought to initial focus on a phase-conjugate mirror. The phase-conjugate mirror would send a phase-conjugate image back, along the path of the incoming light, to the primary mirror. A transparent, highly efficient diffractive thin film deposited on the primary mirror would direct the phase-conjugate image to the imaging instrument(s).

The necessity of microscopy to characterize the optical properties of size-selected, nonspherical aerosol particles.

PubMed

Veghte, Daniel P; Freedman, Miriam A

2012-11-06

It is currently unknown whether mineral dust causes a net warming or cooling effect on the climate system. This uncertainty stems from the varied and evolving shape and composition of mineral dust, which leads to diverse interactions of dust with solar and terrestrial radiation. To investigate these interactions, we have used a cavity ring-down spectrometer to study the optical properties of size-selected calcium carbonate particles, a reactive component of mineral dust. The size selection of nonspherical particles like mineral dust can differ from spherical particles in the polydispersity of the population selected. To calculate the expected extinction cross sections, we use Mie scattering theory for monodisperse spherical particles and for spherical particles with the polydispersity observed in transmission electron microscopy images. Our results for calcium carbonate are compared to the well-studied system of ammonium sulfate. While ammonium sulfate extinction cross sections agree with Mie scattering theory for monodisperse spherical particles, the results for calcium carbonate deviate at large and small particle sizes. We find good agreement for both systems, however, between the calculations performed using the particle images and the cavity ring-down data, indicating that both ammonium sulfate and calcium carbonate can be treated as polydisperse spherical particles. Our results indicate that having an independent measure of polydispersity is essential for understanding the optical properties of nonspherical particles measured with cavity ring-down spectroscopy. Our combined spectroscopy and microscopy techniques demonstrate a novel method by which cavity ring-down spectroscopy can be extended for the study of more complex aerosol particles.

Development of high power UV irradiance meter calibration device

NASA Astrophysics Data System (ADS)

Xia, Ming; Gao, Jianqiang; Yin, Dejin; Li, Tiecheng

2016-09-01

With the rapid development of China's economy, many industries have more requirements for UV light applications, such as machinery manufacturing, aircraft manufacturing using high power UV light for detection, IT industry using high power UV light for curing component assembly, building materials, ink, paint and other industries using high power UV light for material aging test etc. In these industries, there are many measuring instruments for high power UV irradiance which are need to traceability. But these instruments are mostly imported instruments, these imported UV radiation meter are large range, wide wavelength range and high accuracy. They have exceeded our existing calibration capability. Expand the measuring range and improve the measurement accuracy of UV irradiance calibration device is a pressing matter of the moment. The newly developed high power UV irradiance calibration device is mainly composed of high power UV light, UV filter, condenser, UV light guide, optical alignment system, standard cavity absolute radiometer. The calibration device is using optical alignment system to form uniform light radiation field. The standard is standard cavity absolute radiometer, which can through the electrical substitution method, by means of adjusting and measuring the applied DC electric power at the receiver on a heating wire, which is equivalent to the thermo-electromotive force generated by the light radiation power, to achieve absolute optical radiation measurement. This method is the commonly used effective method for accurate measurement of light irradiation. The measuring range of calibration device is (0.2 200) mW/cm2, and the uncertainty of measurement results can reached 2.5% (k=2).

Optical contacting of quartz

NASA Technical Reports Server (NTRS)

Payne, L. L.

1982-01-01

The strength of the bond between optically contacted quartz surfaces was investigated. The Gravity Probe-B (GP-B) experiment to test the theories of general relativity requires extremely precise measurements. The quartz components of the instruments to make these measurements must be held together in a very stable unit. Optical contacting is suggested as a possible method of joining these components. The fundamental forces involved in optical contacting are reviewed and relates calculations of these forces to the results obtained in experiments.

Cavity-enhanced optical bottle beam as a mechanical amplifier

NASA Astrophysics Data System (ADS)

Freegarde, Tim; Dholakia, Kishan

2002-07-01

We analyze the resonant cavity enhancement of a hollow ``optical bottle beam'' for the dipole-force trapping of dark-field-seeking species. We first improve upon the basic bottle beam by adding further Laguerre-Gaussian components to deepen the confining potential. Each of these components itself corresponds to a superposition of transverse cavity modes, which are then enhanced simultaneously in a confocal cavity to produce a deep optical trap needing only a modest incident power. The response of the trapping field to displacement of the cavity mirrors offers an unusual form of mechanical amplifier in which the Gouy phase shift produces an optical Vernier scale between the Laguerre-Gaussian beam components.

The two-component afterglow of Swift GRB 050802

NASA Astrophysics Data System (ADS)

Oates, S. R.; de Pasquale, M.; Page, M. J.; Blustin, A. J.; Zane, S.; McGowan, K.; Mason, K. O.; Poole, T. S.; Schady, P.; Roming, P. W. A.; Page, K. L.; Falcone, A.; Gehrels, N.

2007-09-01

This paper investigates GRB 050802, one of the best examples of a Swift gamma-ray burst afterglow that shows a break in the X-ray light curve, while the optical counterpart decays as a single power law. This burst has an optically bright afterglow of 16.5 mag, detected throughout the 170-650nm spectral range of the Ultraviolet and Optical Telescope (UVOT) onboard Swift. Observations began with the X-ray Telescope and UVOT telescopes 286s after the initial trigger and continued for 1.2 ×106s. The X-ray light curve consists of three power-law segments: a rise until 420s, followed by a slow decay with α =0.63 +/-0.03 until 5000s, after which, the light curve decays faster with a slope of α3 =1.59 +/-0.03. The optical light curve decays as a single power law with αO =0.82 +/-0.03 throughout the observation. The X-ray data on their own are consistent with the break at 5000s being due to the end of energy injection. Modelling the optical to X-ray spectral energy distribution, we find that the optical afterglow cannot be produced by the same component as the X-ray emission at late times, ruling out a single-component afterglow. We therefore considered two-component jet models and find that the X-ray and optical emission is best reproduced by a model in which both components are energy injected for the duration of the observed afterglow and the X-ray break at 5000s is due to a jet break in the narrow component. This bright, well-observed burst is likely a guide for interpreting the surprising finding of Swift that bursts seldom display achromatic jet breaks.

Fiber Ring Optical Gyroscope (FROG)

NASA Technical Reports Server (NTRS)

1979-01-01

The design, construction, and testing of a one meter diameter fiber ring optical gyro, using 1.57 kilometers of single mode fiber, are described. The various noise components: electronic, thermal, mechanical, and optical, were evaluated. Both dc and ac methods were used. An attempt was made to measure the Earth rotation rate; however, the results were questionable because of the optical and electronic noise present. It was concluded that fiber ring optical gyroscopes using all discrete components have many serious problems that can only be overcome by discarding the discrete approach and adapting an all integrated optic technique that has the laser source, modulator, detector, beamsplitters, and bias element on a single chip.

Accurate frequency and time dissemination in the optical domain

NASA Astrophysics Data System (ADS)

Khabarova, K. Yu; Kalganova, E. S.; Kolachevsky, N. N.

2018-02-01

The development of the optical frequency comb technique has enabled a wide use of atomic optical clocks by allowing frequency conversion from the optical to the radio frequency range. Today, the fractional instability of such clocks has reached the record eighteen-digit level, two orders of magnitude better than for cesium fountains representing the primary frequency standard. This is paralleled by the development of techniques for transferring accurate time and optical frequency signals, including fiber links. With this technology, the fractional instability of transferred frequency can be lowered to below 10‑18 with an averaging time of 1000 s for a 1000 km optical link. At a distance of 500 km, a time signal uncertainty of 250 ps has been achieved. Optical links allow comparing optical clocks and creating a synchronized time and frequency standard network at a new level of precision. Prospects for solving new problems arise, including the determination of the gravitational potential, the measurement of the continental Sagnac effect, and precise tests of fundamental theories.

Laser pulse detection method and apparatus

NASA Technical Reports Server (NTRS)

Goss, W.; Janesick, J. R. (Inventor)

1984-01-01

A sensor is described for detecting the difference in phase of a pair of returned light pulse components, such as two components of a light pulse of an optical gyro. In an optic gyro, the two light components have passed in opposite directions through a coil of optical fiber, with the difference in phase of the returned light components determining the intensity of light shining on the sensor. The sensor includes a CCD (charge coupled device) that receives the pair of returned light components to generate a charge proportional to the number of photons in the received light. The amount of the charge represents the phase difference between the two light components. At a time after the transmission of the light pulse and before the expected time of arrival of the interfering light components, charge accumulating in the CCD as a result of reflections from components in the system, are repeatedly removed from the CCD, by transferring out charges in the CCD and dumping these charges.

Uncertainty and sensitivity assessment of flood risk assessments

NASA Astrophysics Data System (ADS)

de Moel, H.; Aerts, J. C.

2009-12-01

Floods are one of the most frequent and costly natural disasters. In order to protect human lifes and valuable assets from the effect of floods many defensive structures have been build. Despite these efforts economic losses due to catastrophic flood events have, however, risen substantially during the past couple of decades because of continuing economic developments in flood prone areas. On top of that, climate change is expected to affect the magnitude and frequency of flood events. Because these ongoing trends are expected to continue, a transition can be observed in various countries to move from a protective flood management approach to a more risk based flood management approach. In a risk based approach, flood risk assessments play an important role in supporting decision making. Most flood risk assessments assess flood risks in monetary terms (damage estimated for specific situations or expected annual damage) in order to feed cost-benefit analysis of management measures. Such flood risk assessments contain, however, considerable uncertainties. This is the result from uncertainties in the many different input parameters propagating through the risk assessment and accumulating in the final estimate. Whilst common in some other disciplines, as with integrated assessment models, full uncertainty and sensitivity analyses of flood risk assessments are not so common. Various studies have addressed uncertainties regarding flood risk assessments, but have mainly focussed on the hydrological conditions. However, uncertainties in other components of the risk assessment, like the relation between water depth and monetary damage, can be substantial as well. This research therefore tries to assess the uncertainties of all components of monetary flood risk assessments, using a Monte Carlo based approach. Furthermore, the total uncertainty will also be attributed to the different input parameters using a variance based sensitivity analysis. Assessing and visualizing the uncertainties of the final risk estimate will be helpful to decision makers to make better informed decisions and attributing this uncertainty to the input parameters helps to identify which parameters are most important when it comes to uncertainty in the final estimate and should therefore deserve additional attention in further research.

Climate change risk analysis framework (CCRAF) a probabilistic tool for analyzing climate change uncertainties

NASA Astrophysics Data System (ADS)

Legget, J.; Pepper, W.; Sankovski, A.; Smith, J.; Tol, R.; Wigley, T.

2003-04-01

Potential risks of human-induced climate change are subject to a three-fold uncertainty associated with: the extent of future anthropogenic and natural GHG emissions; global and regional climatic responses to emissions; and impacts of climatic changes on economies and the biosphere. Long-term analyses are also subject to uncertainty regarding how humans will respond to actual or perceived changes, through adaptation or mitigation efforts. Explicitly addressing these uncertainties is a high priority in the scientific and policy communities Probabilistic modeling is gaining momentum as a technique to quantify uncertainties explicitly and use decision analysis techniques that take advantage of improved risk information. The Climate Change Risk Assessment Framework (CCRAF) presented here a new integrative tool that combines the probabilistic approaches developed in population, energy and economic sciences with empirical data and probabilistic results of climate and impact models. The main CCRAF objective is to assess global climate change as a risk management challenge and to provide insights regarding robust policies that address the risks, by mitigating greenhouse gas emissions and by adapting to climate change consequences. The CCRAF endogenously simulates to 2100 or beyond annual region-specific changes in population; GDP; primary (by fuel) and final energy (by type) use; a wide set of associated GHG emissions; GHG concentrations; global temperature change and sea level rise; economic, health, and biospheric impacts; costs of mitigation and adaptation measures and residual costs or benefits of climate change. Atmospheric and climate components of CCRAF are formulated based on the latest version of Wigley's and Raper's MAGICC model and impacts are simulated based on a modified version of Tol's FUND model. The CCRAF is based on series of log-linear equations with deterministic and random components and is implemented using a Monte-Carlo method with up to 5000 variants per set of fixed input parameters. The shape and coefficients of CCRAF equations are derived from regression analyses of historic data and expert assessments. There are two types of random components in CCRAF - one reflects a year-to-year fluctuations around the expected value of a given variable (e.g., standard error of the annual GDP growth) and another is fixed within each CCRAF variant and represents some essential constants within a "world" represented by that variant (e.g., the value of climate sensitivity). Both types of random components are drawn from pre-defined probability distributions functions developed based on historic data or expert assessments. Preliminary CCRAF results emphasize the relative importance of uncertainties associated with the conversion of GHG and particulate emissions into radiative forcing and quantifying climate change effects at the regional level. A separates analysis involves an "adaptive decision-making", which optimizes the expected future policy effects given the estimated probabilistic uncertainties. As uncertainty for some variables evolve over the time steps, the decisions also adapt. This modeling approach is feasible only with explicit modeling of uncertainties.

Intolerance of uncertainty in adolescents: correlations with worry, social anxiety, and depression.

PubMed

Boelen, Paul A; Vrinssen, Inge; van Tulder, Floor

2010-03-01

The current study examined Intolerance of Uncertainty (IU)-the tendency to react negatively to situations that are uncertain-in psychological problems among adolescents. Using data from 191 adolescents, aged 14 to 18, we examined (a) the dimensionality of IU as tapped by the Intolerance of Uncertainty Scale short-form (IUS-12), (b) the relationship of IU with worry, social anxiety, and depression, (c) the specificity of IU to these variables, and (d) the role of IU as a mediator of the linkages between negative affectivity (NA) and worry, social anxiety, and depression. Results showed that the IUS-12 encompassed 2 components of IU, named Prospective Anxiety and Inhibitory Anxiety. Furthermore, IU was specifically related with worry and social anxiety, but not depression, when controlling the shared variance between these variables and NA, age, and gender. Finally, IU and its 2 components were found to mediate the linkages of NA with worry and social anxiety.

Fine carbonaceous aerosol characteristics at a megacity during the Chinese Spring Festival as given by OC/EC online measurements

NASA Astrophysics Data System (ADS)

Liu, Baoshuang; Bi, Xiaohui; Feng, Yinchang; Dai, Qili; Xiao, Zhimei; Li, Liwei; Wu, Jianhui; Yuan, Jie; Zhang, YuFen

2016-11-01

The OC/EC online monitoring campaign was carried out in Tianjin of China from 8th February to 15th March 2015 during the Chinese Spring Festival period (CSFP). The concentrations of OC, EC, BC and other ambient pollutants (e.g. SO2, NO2 and PM2.5, etc.) in high time resolution were measured with related online-monitoring instruments. During the CSFP, according to the peaks of PM2.5 concentrations and number concentrations (NC) of aerosol particles with aerodynamic diameters between 0.3 and 2.5 μm, five pollution-events were generally identified and displayed. These pollution-events were closely associated with large-scale fireworks displaying, combustion activities such as heating for winter, and the stable meteorological conditions, etc. During the CSFP, EC and OC concentrations showed variations up to one order of magnitude. The uncertainty of instrument itself and the difference for measured methods, further caused the differences between thermal OC (measured OC by thermal method) and optical OC (measured OC by optical method) concentrations, as well as between thermal EC (measured EC by thermal method) and optical EC (measured EC by optical method) concentrations. The high-concentration carbonaceous aerosols could enlarge the uncertainty of measuring instrument, reducing the correlations between OC and EC, and enhance the differences among thermal EC, optical BC and optical EC. The OC/EC ratios and the percentages of SOC/OC would be declined, when the pollution-events formed during the CSFP. Due to the different sources for thermal POC and thermal SOC, the correlation of the two was relatively lower (R2 = 0.39). Thermal POC dominated over thermal OC during the CSFP.

Electro-optically actuated liquid-lens zoom

NASA Astrophysics Data System (ADS)

Pütsch, O.; Loosen, P.

2012-06-01

Progressive miniaturization and mass market orientation denote a challenge to the design of dynamic optical systems such as zoom-lenses. Two working principles can be identified: mechanical actuation and application of active optical components. Mechanical actuation changes the focal length of a zoom-lens system by varying the axial positions of optical elements. These systems are limited in speed and often require complex coupled movements. However, well established optical design approaches can be applied. In contrast, active optical components change their optical properties by varying their physical structure by means of applying external electric signals. An example are liquidlenses which vary their curvatures to change the refractive power. Zoom-lenses benefit from active optical components in two ways: first, no moveable structures are required and second, fast response characteristics can be realized. The precommercial development of zoom-lenses demands simplified and cost-effective system designs. However the number of efficient optical designs for electro-optically actuated zoom-lenses is limited. In this paper, the systematic development of an electro-optically actuated zoom-lens will be discussed. The application of aberration polynomials enables a better comprehension of the primary monochromatic aberrations at the lens elements during a change in magnification. This enables an enhanced synthesis of the system behavior and leads to a simplified zoom-lens design with no moving elements. The change of focal length is achieved only by varying curvatures of targeted integrated electro-optically actuated lenses.

Chaotic Brillouin optical correlation-domain analysis

NASA Astrophysics Data System (ADS)

Zhang, Jianzhong; Zhang, Mingtao; Zhang, Mingjiang; Liu, Yi; Feng, Changkun; Wang, Yahui; Wang, Yuncai

2018-04-01

We propose and experimentally demonstrate a chaotic Brillouin optical correlation-domain analysis (BOCDA) system for distributed fiber sensing. The utilization of the chaotic laser with low coherent state ensures high spatial resolution. The experimental results demonstrate a 3.92-cm spatial resolution over a 906-m measurement range. The uncertainty in the measurement of the local Brillouin frequency shift is 1.2MHz. The measurement signal-to-noise ratio is given, which is agreement with the theoretical value.

Heterogeneous 3D optrode with variable spatial resolution for optogenetic stimulation and electrophysiological recording.

PubMed

Ayub, Suleman; Barz, Falk; Paul, Oliver; Ruther, Patrick

2016-08-01

We report on the concept, development, and geometrical, optical as well as electrical characterization of the first three-dimensional (3D) optrode. This new device allows to optically interact with neuronal cells and simultaneously record their response with a high spatial resolution. Our design is based on a single-shank optical stimulation component and a multi-shank recording probe stacked together in a delicate assembly process. The electrical connection of both components is ensured by using flexible polyimide (PI) ribbon cables. The highly accurate relative positioning and precise alignment of the optical and electrical components in 3D with an optical output power at 460 nm well above 5 mW/mm2 and an all-electrical interface makes this device a promising tool for optogenetic experiments in neuroscientific research.

Multivariate Geostatistical Analysis of Uncertainty for the Hydrodynamic Model of a Geological Trap for Carbon Dioxide Storage. Case study: Multilayered Geological Structure Vest Valcele, ROMANIA

NASA Astrophysics Data System (ADS)

Scradeanu, D.; Pagnejer, M.

2012-04-01

The purpose of the works is to evaluate the uncertainty of the hydrodynamic model for a multilayered geological structure, a potential trap for carbon dioxide storage. The hydrodynamic model is based on a conceptual model of the multilayered hydrostructure with three components: 1) spatial model; 2) parametric model and 3) energy model. The necessary data to achieve the three components of the conceptual model are obtained from: 240 boreholes explored by geophysical logging and seismic investigation, for the first two components, and an experimental water injection test for the last one. The hydrodinamic model is a finite difference numerical model based on a 3D stratigraphic model with nine stratigraphic units (Badenian and Oligocene) and a 3D multiparameter model (porosity, permeability, hydraulic conductivity, storage coefficient, leakage etc.). The uncertainty of the two 3D models was evaluated using multivariate geostatistical tools: a)cross-semivariogram for structural analysis, especially the study of anisotropy and b)cokriging to reduce estimation variances in a specific situation where is a cross-correlation between a variable and one or more variables that are undersampled. It has been identified important differences between univariate and bivariate anisotropy. The minimised uncertainty of the parametric model (by cokriging) was transferred to hydrodynamic model. The uncertainty distribution of the pressures generated by the water injection test has been additional filtered by the sensitivity of the numerical model. The obtained relative errors of the pressure distribution in the hydrodynamic model are 15-20%. The scientific research was performed in the frame of the European FP7 project "A multiple space and time scale approach for the quantification of deep saline formation for CO2 storage(MUSTANG)".

View angle dependence of cloud optical thicknesses retrieved by MODIS

NASA Technical Reports Server (NTRS)

Marshak, Alexander; Varnai, Tamas

2005-01-01

This study examines whether cloud inhomogeneity influences the view angle dependence of MODIS cloud optical thickness (tau) retrieval results. The degree of cloud inhomogeneity is characterized through the local gradient in 11 microns brightness temperature. The analysis of liquid phase clouds in a one year long global dataset of Collection 4 MODIS data reveals that while optical thickness retrievals give remarkably consistent results for all view directions if clouds are homogeneous, they give much higher tau-values for oblique views than for overhead views if clouds are inhomogeneous and the sun is fairly oblique. For solar zenith angles larger than 55deg, the mean optical thickness retrieved for the most inhomogeneous third of cloudy pixels is more than 30% higher for oblique views than for overhead views. After considering a variety of possible scenarios, the paper concludes that the most likely reason for the increase lies in three-dimensional radiative interactions that are not considered in current, one-dimensional retrieval algorithms. Namely, the radiative effect of cloud sides viewed at oblique angles seems to contribute most to the enhanced tau-values. The results presented here will help understand cloud retrieval uncertainties related to cloud inhomogeneity. They complement the uncertainty estimates that will start accompanying MODIS cloud products in Collection 5 and may eventually help correct for the observed view angle dependent biases.

Towards an integrated strategy for monitoring wetland inundation with virtual constellations of optical and radar satellites

NASA Astrophysics Data System (ADS)

DeVries, B.; Huang, W.; Huang, C.; Jones, J. W.; Lang, M. W.; Creed, I. F.; Carroll, M.

2017-12-01

The function of wetlandscapes in hydrological and biogeochemical cycles is largely governed by surface inundation, with small wetlands that experience periodic inundation playing a disproportionately large role in these processes. However, the spatial distribution and temporal dynamics of inundation in these wetland systems are still poorly understood, resulting in large uncertainties in global water, carbon and greenhouse gas budgets. Satellite imagery provides synoptic and repeat views of the Earth's surface and presents opportunities to fill this knowledge gap. Despite the proliferation of Earth Observation satellite missions in the past decade, no single satellite sensor can simultaneously provide the spatial and temporal detail needed to adequately characterize inundation in small, dynamic wetland systems. Surface water data products must therefore integrate observations from multiple satellite sensors in order to address this objective, requiring the development of improved and coordinated algorithms to generate consistent estimates of surface inundation. We present a suite of algorithms designed to detect surface inundation in wetlands using data from a virtual constellation of optical and radar sensors comprising the Landsat and Sentinel missions (DeVries et al., 2017). Both optical and radar algorithms were able to detect inundation in wetlands without the need for external training data, allowing for high-efficiency monitoring of wetland inundation at large spatial and temporal scales. Applying these algorithms across a gradient of wetlands in North America, preliminary findings suggest that while these fully automated algorithms can detect wetland inundation at higher spatial and temporal resolutions than currently available surface water data products, limitations specific to the satellite sensors and their acquisition strategies are responsible for uncertainties in inundation estimates. Further research is needed to investigate strategies for integrating optical and radar data from virtual constellations, with a focus on reducing uncertainties, maximizing spatial and temporal detail, and establishing consistent records of wetland inundation over time. The findings and conclusions in this article do not necessarily represent the views of the U.S. Government.

Reference dataset of volcanic ash physicochemical and optical properties for atmospheric measurement retrievals and transport modelling

NASA Astrophysics Data System (ADS)

Vogel, Andreas; Durant, Adam; Sytchkova, Anna; Diplas, Spyros; Bonadonna, Costanza; Scarnato, Barbara; Krüger, Kirstin; Kylling, Arve; Kristiansen, Nina; Stohl, Andreas

2016-04-01

Explosive volcanic eruptions emit up to 50 wt.% (total erupted mass) of fine ash particles (<63 microns), which individually can have theoretical atmospheric lifetimes that span hours to days. Depending on the injection height, fine ash may be subsequently transported and dispersed by the atmosphere over 100s - 1000s km and can pose a major threat for aviation operations. Recent volcanic eruptions, such as the 2010 Icelandic Eyjafjallajökull event, illustrated how volcanic ash can severely impact commercial air traffic. In order to manage the threat, it is important to have accurate forecast information on the spatial extent and absolute quantity of airborne volcanic ash. Such forecasts are constrained by empirically-derived estimates of the volcanic source term and the nature of the constituent volcanic ash properties. Consequently, it is important to include a quantitative assessment of measurement uncertainties of ash properties to provide realistic ash forecast uncertainty. Currently, information on volcanic ash physicochemical and optical properties is derived from a small number of somewhat dated publications. In this study, we provide a reference dataset for physical (size distribution and shape), chemical (bulk vs. surface chemistry) and optical properties (complex refractive index in the UV-vis-NIR range) of a representative selection of volcanic ash samples from 10 different volcanic eruptions covering the full variability in silica content (40-75 wt.% SiO2). Through the combination of empirical analytical methods (e.g., image analysis, Energy Dispersive Spectroscopy, X-ray Photoelectron Spectroscopy, Transmission Electron Microscopy and UV/Vis/NIR/FTIR Spectroscopy) and theoretical models (e.g., Bruggeman effective medium approach), it was possible to fully capture the natural variability of ash physicochemical and optical characteristics. The dataset will be applied in atmospheric measurement retrievals and atmospheric transport modelling to determine the sensitivity to uncertainty in ash particle characteristics.

An Exploration of Professional Culture Differentials and Their Potential Impact on the Information Assurance Component of Optical Transmission Networks Design

ERIC Educational Resources Information Center

Cuthrell, Michael Gerard

2011-01-01

Optical transmission networks are an integral component of the critical infrastructures for many nations. Many people believe that optical transmission networks are impenetrable. In actuality, these networks possess weaknesses that can be exploited to bring about harm. An emerging Information Assurance (IA) industry has as its goals: to…

PTV margin determination in conformal SRT of intracranial lesions

PubMed Central

Parker, Brent C.; Shiu, Almon S.; Maor, Moshe H.; Lang, Frederick F.; Liu, H. Helen; White, R. Allen; Antolak, John A.

2002-01-01

The planning target volume (PTV) includes the clinical target volume (CTV) to be irradiated and a margin to account for uncertainties in the treatment process. Uncertainties in miniature multileaf collimator (mMLC) leaf positioning, CT scanner spatial localization, CT‐MRI image fusion spatial localization, and Gill‐Thomas‐Cosman (GTC) relocatable head frame repositioning were quantified for the purpose of determining a minimum PTV margin that still delivers a satisfactory CTV dose. The measured uncertainties were then incorporated into a simple Monte Carlo calculation for evaluation of various margin and fraction combinations. Satisfactory CTV dosimetric criteria were selected to be a minimum CTV dose of 95% of the PTV dose and at least 95% of the CTV receiving 100% of the PTV dose. The measured uncertainties were assumed to be Gaussian distributions. Systematic errors were added linearly and random errors were added in quadrature assuming no correlation to arrive at the total combined error. The Monte Carlo simulation written for this work examined the distribution of cumulative dose volume histograms for a large patient population using various margin and fraction combinations to determine the smallest margin required to meet the established criteria. The program examined 5 and 30 fraction treatments, since those are the only fractionation schemes currently used at our institution. The fractionation schemes were evaluated using no margin, a margin of just the systematic component of the total uncertainty, and a margin of the systematic component plus one standard deviation of the total uncertainty. It was concluded that (i) a margin of the systematic error plus one standard deviation of the total uncertainty is the smallest PTV margin necessary to achieve the established CTV dose criteria, and (ii) it is necessary to determine the uncertainties introduced by the specific equipment and procedures used at each institution since the uncertainties may vary among locations. PACS number(s): 87.53.Kn, 87.53.Ly PMID:12132939