Scaling induced performance challenges/limitations of on-chip metal interconnects and comparisons with optical interconnects

NASA Astrophysics Data System (ADS)

Kapur, Pawan

The miniaturization paradigm for silicon integrated circuits has resulted in a tremendous cost and performance advantage. Aggressive shrinking of devices provides faster transistors and a greater functionality for circuit design. However, scaling induced smaller wire cross-sections coupled with longer lengths owing to larger chip areas, result in a steady deterioration of interconnects. This degradation in interconnect trends threatens to slow down the rapid growth along Moore's law. This work predicts that the situation is worse than anticipated. It shows that in the light of technology and reliability constraints, scaling induced increase in electron surface scattering, fractional cross section area occupied by the highly resistive barrier, and realistic interconnect operation temperature will lead to a significant rise in effective resistivity of modern copper based interconnects. We start by discussing various technology factors affecting copper resistivity. We, next, develop simulation tools to model these effects. Using these tools, we quantify the increase in realistic copper resistivity as a function of future technology nodes, under various technology assumptions. Subsequently, we evaluate the impact of these technology effects on delay and power dissipation of global signaling interconnects. Modern long on-chip wires use repeaters, which dramatically improves their delay and bandwidth. We quantify the repeated wire delays and power dissipation using realistic resistance trends at future nodes. With the motivation of reducing power, we formalize a methodology, which trades power with delay very efficiently for repeated wires. Using this method, we find that although the repeater power comes down, the total power dissipation due to wires is still found to be very large at future nodes. Finally, we explore optical interconnects as a possible substitute, for specific interconnect applications. We model an optical receiver and waveguides. Using this we assess future optical system performance. Finally, we compare the delay and power of future metal interconnects with that of optical interconnects for global signaling application. We also compare the power dissipation of the two approaches for an upper level clock distribution application. We find that for long on-chip communication links, optical interconnects have lower latencies than future metal interconnects at comparable levels of power dissipation.

Polarization modeling and predictions for DKIST part 2: application of the Berreman calculus to spectral polarization fringes of beamsplitters and crystal retarders

NASA Astrophysics Data System (ADS)

Harrington, David M.; Snik, Frans; Keller, Christoph U.; Sueoka, Stacey R.; van Harten, Gerard

2017-10-01

We outline polarization fringe predictions derived from an application of the Berreman calculus for the Daniel K. Inouye Solar Telescope (DKIST) retarder optics. The DKIST retarder baseline design used six crystals, single-layer antireflection coatings, thick cover windows, and oil between all optical interfaces. This tool estimates polarization fringes and optic Mueller matrices as functions of all optical design choices. The amplitude and period of polarized fringes under design changes, manufacturing errors, tolerances, and several physical factors can now be estimated. This tool compares well with observations of fringes for data collected with the spectropolarimeter for infrared and optical regions at the Dunn Solar Telescope using bicrystalline achromatic retarders as well as laboratory tests. With this tool, we show impacts of design decisions on polarization fringes as impacted by antireflection coatings, oil refractive indices, cover window presence, and part thicknesses. This tool helped DKIST decide to remove retarder cover windows and also recommends reconsideration of coating strategies for DKIST. We anticipate this tool to be essential in designing future retarders for mitigation of polarization and intensity fringe errors in other high spectral resolution astronomical systems.

Comparative study of 2-DOF micromirrors for precision light manipulation

NASA Astrophysics Data System (ADS)

Young, Johanna I.; Shkel, Andrei M.

2001-08-01

Many industry experts predict that the future of fiber optic telecommunications depends on the development of all-optical components for switching of photonic signals from fiber to fiber throughout the networks. MEMS is a promising technology for providing all-optical switching at high speeds with significant cost reductions. This paper reports on the the analysis of two designs for 2-DOF electrostatically actuated MEMS micromirrors for precision controllable large optical switching arrays. The behavior of the micromirror designs is predicted by coupled-field electrostatic and modal analysis using a finite element analysis (FEA) multi-physics modeling software. The analysis indicates that the commonly used gimbal type mirror design experiences electrostatic interference and would therefore be difficult to precisely control for 2-DOF motion. We propose a new design approach which preserves 2-DOF actuation while minimizing electrostatic interference between the drive electrodes and the mirror. Instead of using two torsional axes, we use one actuator which combines torsional and flexural DOFs. A comparative analysis of the conventional gimbal design and the one proposed in this paper is performed.

Optical Processing Techniques For Pseudorandom Sequence Prediction

NASA Astrophysics Data System (ADS)

Gustafson, Steven C.

1983-11-01

Pseudorandom sequences are series of apparently random numbers generated, for example, by linear or nonlinear feedback shift registers. An important application of these sequences is in spread spectrum communication systems, in which, for example, the transmitted carrier phase is digitally modulated rapidly and pseudorandomly and in which the information to be transmitted is incorporated as a slow modulation in the pseudorandom sequence. In this case the transmitted information can be extracted only by a receiver that uses for demodulation the same pseudorandom sequence used by the transmitter, and thus this type of communication system has a very high immunity to third-party interference. However, if a third party can predict in real time the probable future course of the transmitted pseudorandom sequence given past samples of this sequence, then interference immunity can be significantly reduced.. In this application effective pseudorandom sequence prediction techniques should be (1) applicable in real time to rapid (e.g., megahertz) sequence generation rates, (2) applicable to both linear and nonlinear pseudorandom sequence generation processes, and (3) applicable to error-prone past sequence samples of limited number and continuity. Certain optical processing techniques that may meet these requirements are discussed in this paper. In particular, techniques based on incoherent optical processors that perform general linear transforms or (more specifically) matrix-vector multiplications are considered. Computer simulation examples are presented which indicate that significant prediction accuracy can be obtained using these transforms for simple pseudorandom sequences. However, the useful prediction of more complex pseudorandom sequences will probably require the application of more sophisticated optical processing techniques.

Novel optical gyroscope: proof of principle demonstration and future scope

PubMed Central

Srivastava, Shailesh; Rao D. S., Shreesha; Nandakumar, Hari

2016-01-01

We report the first proof-of-principle demonstration of the resonant optical gyroscope with reflector that we have recently proposed. The device is very different from traditional optical gyroscopes since it uses the inherent coupling between the clockwise and counterclockwise propagating waves to sense the rotation. Our demonstration confirms our theoretical analysis and simulations. We also demonstrate a novel method of biasing the gyroscope using orthogonal polarization states. The simplicity of the structure and the readout method, the theoretically predicted high sensitivities (better than 0.001 deg/hr), and the possibility of further performance enhancement using a related laser based active device, all have immense potential for attracting fresh research and technological initiatives. PMID:27694987

Prediction of nonlinear optical properties of organic materials. General theoretical considerations

NASA Technical Reports Server (NTRS)

Cardelino, B.; Moore, C.; Zutaut, S.

1993-01-01

The prediction of nonlinear optical properties of organic materials is geared to assist materials scientists in the selection of good candidate molecules. A brief summary of the quantum mechanical methods used for estimating hyperpolarizabilities will be presented. The advantages and limitations of each technique will be discussed. Particular attention will be given to the finite-field method for calculating first and second order hyperpolarizabilities, since this method is better suited for large molecules. Corrections for dynamic fields and bulk effects will be discussed in detail, focusing on solvent effects, conformational isomerization, core effects, dispersion, and hydrogen bonding. Several results will be compared with data obtained from third-harmonic-generation (THG) and dc-induced second harmonic generation (EFISH) measurements. These comparisons will demonstrate the qualitative ability of the method to predict the relative strengths of hyperpolarizabilities of a class of compounds. The future application of molecular mechanics, as well as other techniques, in the study of bulk properties and solid state defects will be addressed. The relationship between large values for nonlinear optical properties and large conjugation lengths is well known, and is particularly important for third-order processes. For this reason, the materials with the largest observed nonresonant third-order properties are conjugated polymers. An example of this type of polymer is polydiacetylene. One of the problems in dealing with polydiacetylene is that substituents which may enhance its nonlinear properties may ultimately prevent it from polymerizing. A model which attempts to predict the likelihood of solid-state polymerization is considered, along with the implications of the assumptions that are used. Calculations of the third-order optical properties and their relationship to first-order properties and energy gaps will be discussed. The relationship between monomeric and polymeric third-order optical properties will also be considered.

Evolution of optical fibre cabling components at CERN: Performance and technology trends analysis

NASA Astrophysics Data System (ADS)

Shoaie, Mohammad Amin; Meroli, Stefano; Machado, Simao; Ricci, Daniel

2018-05-01

CERN optical fibre infrastructure has been growing constantly over the past decade due to ever increasing connectivity demands. The provisioning plan and fibre installation of this vast laboratory is performed by Fibre Optics and Cabling Section at Engineering Department. In this paper we analyze the procurement data for essential fibre cabling components during a five-year interval to extract the existing trends and anticipate future directions. The analysis predicts high contribution of LC connector and an increasing usage of multi-fibre connectors. It is foreseen that single-mode fibres become the main fibre type for mid and long-range installations while air blowing would be the major installation technique. Performance assessment of various connectors shows that the expanded beam ferrule is favored for emerging on-board optical interconnections thanks to its scalable density and stable return-loss.

Designing Optical Properties in DNA-Programmed Nanoparticle Superlattices

NASA Astrophysics Data System (ADS)

Ross, Michael Brendan

A grand challenge of modern science has been the ability to predict and design the properties of new materials. This approach to the a priori design of materials presents a number of challenges including: predictable properties of the material building blocks, a programmable means for arranging such building blocks into well understood architectures, and robust models that can predict the properties of these new materials. In this dissertation, we present a series of studies that describe how optical properties in DNA-programmed nanoparticle superlattices can be predicted prior to their synthesis. The first chapter provides a history and introduction to the study of metal nanoparticle arrays. Chapter 2 surveys and compares several geometric models and electrodynamics simulations with the measured optical properties of DNA-nanoparticle superlattices. Chapter 3 describes silver nanoparticle superlattices (rather than gold) and identifies their promise as plasmonic metamaterials. In chapter 4, the concept of plasmonic metallurgy is introduced, whereby it is demonstrated that concepts from materials science and metallurgy can be applied to the optical properties of mixed metallic plasmonic materials, unveiling rich and tunable optical properties such as color and asymmetric reflectivity. Chapter 5 presents a comprehensive theoretical exploration of anisotropy (non-spherical) in nanoparticle superlattice architectures. The role of anisotropy is discussed both on the nanoscale, where several desirable metamaterial properties can be tuned from the ultraviolet to near-infrared, and on the mesoscale, where the size and shape of a superlattice is demonstrated to have a pronounced effect on the observed far-field optical properties. Chapter 6 builds upon those theoretical data presented in chapter 5, including the experimental realization of size and shape dependent properties in DNA-programmed superlattices. Specifically, nanoparticle spacing is explored as a parameter that can be used to influence the properties of mesoscale single crystal superlattices, such that they exhibit either plasmonic absorption or photonic scattering. This concept is generalized through simulation, which demonstrates that the crystal habit (size, shape, and morphology) is a powerful design parameter for optical properties in mesoscale nanoparticle assemblies. Finally, chapter 7 summarizes these data and their impact, and puts them in context regarding future opportunities. This work presents a comprehensive demonstration that the optical properties of nanoparticle-based architectures can be precisely controlled and deliberately designed a priori using the unique programmability of DNA and the use of several levels of predictive electromagnetic theory.

Few-layer antimonene decorated microfiber: ultra-short pulse generation and all-optical thresholding with enhanced long term stability

NASA Astrophysics Data System (ADS)

Song, Yufeng; Liang, Zhiming; Jiang, Xiantao; Chen, Yunxiang; Li, Zhongjun; Lu, Lu; Ge, Yanqi; Wang, Ke; Zheng, Jilin; Lu, Shunbin; Ji, Jianhua; Zhang, Han

2017-12-01

Antimonene, a new type of mono/few-layer two-dimensional (2D) mono-elemental material purely consisting of antimony similar as graphene and phosphorene, has been theoretically predicted with excellent optical response and enhanced stability. Herein, we experimentally investigated the broadband nonlinear optical response of highly stable few-layer antimonene (FLA) by performing an open-aperture Z-scan laser measurement. Thanks to the direct bandgap and resonant absorption at the telecommunication band, we demonstrated the feasibility of FLA-decorated microfiber not only as an optical saturable absorber for ultrafast photonics operation, but also as a stable all-optical pulse thresholder that can effectively suppress the transmission noise, boost the signal-to-noise ratio (SNR), and reshape the deteriorated input signal. Our findings, as the first prototypic device of absorption of antimonene, might facilitate the development of antimonene-based optical communication technologies towards high stability and practical applications in the future.

Results from SIM's Thermo-Opto-Mechanical (TOM3) Testbed

NASA Technical Reports Server (NTRS)

Goullioud, Renaud; Lindensmith, C. A.; Hahn, I.

2006-01-01

Future space-based optical interferometers, such as the Space Interferometer Mission Planet Quest (SIM), require thermal stability of the optical wavefront to the level of picometers in order to produce astrometric data at the micro-arc-second level. In SIM, the internal path of the interferometer will be measured with a small metrology beam whereas the starlight fringe position is estimated from a large concentric annular beam. To achieve the micro-arc-second observation goal for SIM, it is necessary to maintain the optical path difference between the central and the outer annulus portions of the wavefront of the front-end telescope optics to a few tens of picometers. The Thermo-Opto-Mecha nical testbed (TOM3) was developed at the Jet Propulsion Laboratory to measure thermally induced optical deformations of a full-size flight-like beam compressor and siderostat, the two largest optics on SIM, in flight-like thermal environments. A Common Path Heterodyne Interferometer (COPHI) developed at JPL was used for the fine optical path difference measurement as the metrology sensor. The system was integrated inside a large vacuum chamber in order to mitigate the atmospheric and thermal disturbances. The siderostat was installed in a temperature-controlled thermal shroud inside the vacuum chamber, creating a flight-like thermal environment. Detailed thermal and structural models of the test articles (siderostat and compressor) were also developed for model prediction and correlation of the thermal deformations. Experimental data shows SIM required thermal stability of the test articles and good agreement with the model predictions.

Do Magnetic Fields Drive High-Energy Explosive Transients?

NASA Astrophysics Data System (ADS)

Mundell, Carole

2017-10-01

I will review the current state-of-the-art in real-time, rapid response optical imaging and polarimetric followup of transient sources such as Gamma Ray Bursts. I will interpret current results within the context of the external shock model and present predictions for future mm- and cm-wave radio observatories. Recent observational results from new radio pilot studies will also be presented.

Colloidal crystals with diamond symmetry at optical lengthscales

NASA Astrophysics Data System (ADS)

Wang, Yifan; Jenkins, Ian C.; McGinley, James T.; Sinno, Talid; Crocker, John C.

2017-02-01

Future optical materials promise to do for photonics what semiconductors did for electronics, but the challenge has long been in creating the structure they require--a regular, three-dimensional array of transparent microspheres arranged like the atoms in a diamond crystal. Here we demonstrate a simple approach for spontaneously growing double-diamond (or B32) crystals that contain a suitable diamond structure, using DNA to direct the self-assembly process. While diamond symmetry crystals have been grown from much smaller nanoparticles, none of those previous methods suffice for the larger particles needed for photonic applications, whose size must be comparable to the wavelength of visible light. Intriguingly, the crystals we observe do not readily form in previously validated simulations; nor have they been predicted theoretically. This finding suggests that other unexpected microstructures may be accessible using this approach and bodes well for future efforts to inexpensively mass-produce metamaterials for an array of photonic applications.

Optical diagnosis of small colorectal polyps at routine colonoscopy (Detect InSpect ChAracterise Resect and Discard; DISCARD trial): a prospective cohort study.

PubMed

Ignjatovic, Ana; East, James E; Suzuki, Noriko; Vance, Margaret; Guenther, Thomas; Saunders, Brian P

2009-12-01

Accurate optical diagnosis of small (<10 mm) colorectal polyps in vivo, without formal histopathology, could make colonoscopy more efficient and cost effective. The aim of this study was to assess whether optical diagnosis of small polyps is feasible and safe in routine clinical practice. Consecutive patients with a positive faecal occult blood test or previous adenomas undergoing surveillance at St Mark's Hospital (London, UK), from June 19, 2008, to June 16, 2009, were included in this prospective study. Four colonoscopists with different levels of experience predicted polyp histology using optical diagnosis with high-definition white light, followed by narrow-band imaging without magnification and chromoendoscopy, as required. The primary outcome was accuracy of polyp characterisation using optical diagnosis compared with histopathology, the current gold standard. Accuracy of optical diagnosis to predict the next surveillance interval was also assessed and compared with surveillance intervals predicted by current guidelines using histopathology. This study is registered with ClinicalTrials.gov, NCT00888771. 363 polyps smaller than 10 mm were detected in 130 patients, of which 278 polyps had both optical and histopathological diagnosis. By histology, 198 of these polyps were adenomas and 80 were non-neoplastic lesions (of which 62 were hyperplastic). Optical diagnosis accurately diagnosed 186 of 198 adenomas (sensitivity 0.94; 95% CI 0.90-0.97) and 55 of 62 hyperplastic polyps (specificity 0.89; 0.78-0.95), with an overall accuracy of 241 of 260 (0.93, 0.89-0.96) for polyp characterisation. Using optical diagnosis alone, 82 of 130 patients could be given a surveillance interval immediately after colonoscopy, and the same interval was found after formal histopathology in 80 patients (98%) using British guidelines and in 78 patients (95%) using US multisociety guidelines. For polyps less than 10 mm in size, in-vivo optical diagnosis seems to be an acceptable strategy to assess polyp histopathology and future surveillance intervals. Dispensing with formal histopathology for most small polyps found at colonoscopy could improve the efficiency of the procedure and lead to substantial savings in time and cost. Leigh Family Trust, London, UK.

Penta-P2X (X=C, Si) monolayers as wide-bandgap semiconductors: A first principles prediction

NASA Astrophysics Data System (ADS)

Naseri, Mosayeb; Lin, Shiru; Jalilian, Jaafar; Gu, Jinxing; Chen, Zhongfang

2018-06-01

By means of density functional theory computations, we predicted two novel two-dimensional (2D) nanomaterials, namely P2X (X=C, Si) monolayers with pentagonal configurations. Their structures, stabilities, intrinsic electronic, and optical properties as well as the effect of external strain to the electronic properties have been systematically examined. Our computations showed that these P2C and P2Si monolayers have rather high thermodynamic, kinetic, and thermal stabilities, and are indirect semiconductors with wide bandgaps (2.76 eV and 2.69 eV, respectively) which can be tuned by an external strain. These monolayers exhibit high absorptions in the UV region, but behave as almost transparent layers for visible light in the electromagnetic spectrum. Their high stabilities and exceptional electronic and optical properties suggest them as promising candidates for future applications in UV-light shielding and antireflection layers in solar cells.

Finite Element Methods for Modelling Mechanical Loss in LIGO coating optics.

NASA Astrophysics Data System (ADS)

Newport, Jonathan; Harry, Gregg; LIGO Collaboration

2015-04-01

Gravitational waves from sources such as binary star systems, supernovae explosions and stochastic background radiation have yet to be directly detected by experimental observations. Alongside international collaborators, the Laser Interferometer Gravitational-Wave Observatory (LIGO) is designed to realize detection of gravitational waves using interferometric techniques. The second generation of gravitational wave observatories, known as Advanced LIGO, are currently undergoing installation and commissioning at sites in Hanford, Washington and Livingston, Louisiana. The ultimate sensitivity of Advanced LIGO within select spectral bands is limited by thermal noise in the coatings of the interferometer optics. The LIGO lab at American University is measuring the mechanical loss of coated substrates to predict thermal noise within these spectral bands. These predictions use increasingly sophisticated finite element models to ensure the ultimate design sensitivity of Advanced LIGO and to study coating and substrate materials for future gravitational wave detectors.

Progress with the lick adaptive optics system

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

Gavel, D T; Olivier, S S; Bauman, B

2000-03-01

Progress and results of observations with the Lick Observatory Laser Guide Star Adaptive Optics System are presented. This system is optimized for diffraction-limited imaging in the near infrared, 1-2 micron wavelength bands. We describe our development efforts in a number of component areas including, a redesign of the optical bench layout, the commissioning of a new infrared science camera, and improvements to the software and user interface. There is also an ongoing effort to characterize the system performance with both natural and laser guide stars and to fold this data into a refined system model. Such a model can bemore » used to help plan future observations, for example, predicting the point-spread function as a function of seeing and guide star magnitude.« less

The Future of Satellite-based Lightning Detection

NASA Technical Reports Server (NTRS)

Bocippio, Dennis J.; Christian, Hugh J.; Arnold, James E. (Technical Monitor)

2001-01-01

The future of satellite-based optical lightning detection, beyond the end of the current TRMM mission, is discussed. Opportunities for new low-earth orbit missions are reviewed. The potential for geostationary observations is significant; such observations provide order-of-magnitude gains in sampling and data efficiency over existing satellite convective observations. The feasibility and performance (resolution, sensitivity) of geostationary measurements using current technology is discussed. In addition to direct and continuous hemispheric observation of lighting, geostationary measurements have the potential (through data assimilation) to dramatically improve short and medium range forecasts, offering benefits to prediction of NOx productions and/or vertical transport.

Neutrino Flux Prediction for the NuMI Beamline

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

Soplin, Leonidas Aliaga

2016-01-01

The determination of the neutrino flux in any conventional neutrino beam presents a challenge for the current and future short and long baseline neutrino experiments. The uncertainties associated with the production and attenuation of the hadrons in the beamline materials along with those associated with the beam optics have a big effect in the flux spectrum knowledge. For experiments like MINERvA, understanding the flux is crucial since it enters directly into every neutrino-nucleus cross-sections measurements. The foundation of this work is predicting the neutrino flux at MINERvA using dedicated measurements of hadron production in hadron-nucleus collisions and incorporating in-situ MINERvAmore » data that can provide additional constraints. This work also includes the prospect for predicting the flux at other detectors like the NOvA Near detector. The procedure and conclusions of this thesis will have a big impact on future hadron production experiments and on determining the flux for the upcoming DUNE experiment.« less

Neutrino Flux Prediction for the NuMI Beamline

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

Aliaga Soplin, Leonidas

2016-01-01

The determination of the neutrino flux in any conventional neutrino beam presents a challenge for the current and future short and long baseline neutrino experiments. The uncertainties associated with the production and attenuation of the hadrons in the beamline materials along with those associated with the beam optics have a big effect in the flux spectrum knowledge. For experiments like MINERvA, understanding the flux is crucial since it enters directly into every neutrino-nucleus cross-sections measurements. The foundation of this work is predicting the neutrino flux at MINERvA using dedicated measurements of hadron production in hadron-nucleus collisions and incorporating in-situ MINERvAmore » data that can provide additional constraints. This work also includes the prospect for predicting the flux at other detectors like the NOvA Near detector. The procedure and conclusions of this thesis will have a big impact on future hadron production experiments and on determining the fl ux for the upcoming DUNE experiment.« less

Predictor-corrector framework for the sequential assembly of optical systems based on wavefront sensing.

PubMed

Schindlbeck, Christopher; Pape, Christian; Reithmeier, Eduard

2018-04-16

Alignment of optical components is crucial for the assembly of optical systems to ensure their full functionality. In this paper we present a novel predictor-corrector framework for the sequential assembly of serial optical systems. Therein, we use a hybrid optical simulation model that comprises virtual and identified component positions. The hybrid model is constantly adapted throughout the assembly process with the help of nonlinear identification techniques and wavefront measurements. This enables prediction of the future wavefront at the detector plane and therefore allows for taking corrective measures accordingly during the assembly process if a user-defined tolerance on the wavefront error is violated. We present a novel notation for the so-called hybrid model and outline the work flow of the presented predictor-corrector framework. A beam expander is assembled as demonstrator for experimental verification of the framework. The optical setup consists of a laser, two bi-convex spherical lenses each mounted to a five degree-of-freedom stage to misalign and correct components, and a Shack-Hartmann sensor for wavefront measurements.

Augmenting the SCaN Link Budget Tool with Validated Atmospheric Propagation

NASA Technical Reports Server (NTRS)

Steinkerchner, Leo; Welch, Bryan

2017-01-01

In any Earth-Space or Space-Earth communications link, atmospheric effects cause significant signal attenuation. In order to develop a communications system that is cost effective while meeting appropriate performance requirements, it is important to accurately predict these effects for the given link parameters. This project aimed to develop a Matlab(TradeMark) (The MathWorks, Inc.) program that could augment the existing Space Communications and Navigation (SCaN) Link Budget Tool with accurate predictions of atmospheric attenuation of both optical and radio-frequency signals according to the SCaN Optical Link Assessment Model Version 5 and the International Telecommunications Union, Radiocommunications Sector (ITU-R) atmospheric propagation loss model, respectively. When compared to data collected from the Advance Communications Technology Satellite (ACTS), the radio-frequency model predicted attenuation to within 1.3 dB of loss for 95 of measurements. Ultimately, this tool will be integrated into the SCaN Center for Engineering, Networks, Integration, and Communications (SCENIC) user interface in order to support analysis of existing SCaN systems and planning capabilities for future NASA missions.

Performances and reliability predictions of optical data transmission links using a system simulator for aerospace applications

NASA Astrophysics Data System (ADS)

Bechou, L.; Deshayes, Y.; Aupetit-Berthelemot, C.; Guerin, A.; Tronche, C.

Space missions for Earth Observation are called upon to carry a growing number of instruments in their payload, whose performances are increasing. Future space systems are therefore intended to generate huge amounts of data and a key challenge in coming years will therefore lie in the ability to transmit that significant quantity of data to ground. Thus very high data rate Payload Telemetry (PLTM) systems will be required to face the demand of the future Earth Exploration Satellite Systems and reliability is one of the major concern of such systems. An attractive approach associated with the concept of predictive modeling consists in analyzing the impact of components malfunctioning on the optical link performances taking into account the network requirements and experimental degradation laws. Reliability estimation is traditionally based on life-testing and a basic approach is to use Telcordia requirements (468GR) for optical telecommunication applications. However, due to the various interactions between components, operating lifetime of a system cannot be taken as the lifetime of the less reliable component. In this paper, an original methodology is proposed to estimate reliability of an optical communication system by using a dedicated system simulator for predictive modeling and design for reliability. At first, we present frameworks of point-to-point optical communication systems for space applications where high data rate (or frequency bandwidth), lower cost or mass saving are needed. Optoelectronics devices used in these systems can be similar to those found in terrestrial optical network. Particularly we report simulation results of transmission performances after introduction of DFB Laser diode parameters variations versus time extrapolated from accelerated tests based on terrestrial or submarine telecommunications qualification standards. Simulations are performed to investigate and predict the consequence of degradations of the Laser diode (acting as a - requency carrier) on system performances (eye diagram, quality factor and BER). The studied link consists in 4× 2.5 Gbits/s WDM channels with direct modulation and equally spaced (0,8 nm) around the 1550 nm central wavelength. Results clearly show that variation of fundamental parameters such as bias current or central wavelength induces a penalization of dynamic performances of the complete WDM link. In addition different degradation kinetics of aged Laser diodes from a same batch have been implemented to build the final distribution of Q-factor and BER values after 25 years. When considering long optical distance, fiber attenuation, EDFA noise, dispersion, PMD, ... penalize network performances that can be compensated using Forward Error Correction (FEC) coding. Three methods have been investigated in the case of On-Off Keying (OOK) transmission over an unipolar optical channel corrupted by Gaussian noise. Such system simulations highlight the impact of component parameter degradations on the whole network performances allowing to optimize various time and cost consuming sensitivity analyses at the early stage of the system development. Thus the validity of failure criteria in relation with mission profiles can be evaluated representing a significant part of the general PDfR effort in particular for aerospace applications.

First-principles prediction of solar radiation shielding performance for transparent windows of GdB{sub 6}

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

Xiao, Lihua, E-mail: xiaolihua@git.edu.cn; School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083; Guizhou Special Functional Materials 2011 Collaborative Innovation Center, Guizhou Institute of Technology, Guiyang 550003

2016-04-28

The structural, electronic, magnetic, and optical properties of GdB{sub 6} are studied using the first-principles calculations. Calculated values for magnetic and optical properties and lattice constant are found to be consistent with previously reported experimental results. The calculated results show that GdB{sub 6} is a perfect near-infrared absorption/reflectance material that could serve as a solar radiation shielding material for windows with high visible light transmittance, similar to LaB{sub 6}, which is assigned to its plasma oscillation and a collective oscillation (volume plasmon) of carrier electrons. It was found that the magnetic 4f electrons of Gd are not relevant to themore » important optical properties of GdB{sub 6}. These theoretical studies serve as a reference for future studies.« less

Free-Space Optical Interconnect Employing VCSEL Diodes

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Savich, Gregory R.; Torres, Heidi

2009-01-01

Sensor signal processing is widely used on aircraft and spacecraft. The scheme employs multiple input/output nodes for data acquisition and CPU (central processing unit) nodes for data processing. To connect 110 nodes and CPU nodes, scalable interconnections such as backplanes are desired because the number of nodes depends on requirements of each mission. An optical backplane consisting of vertical-cavity surface-emitting lasers (VCSELs), VCSEL drivers, photodetectors, and transimpedance amplifiers is the preferred approach since it can handle several hundred megabits per second data throughput.The next generation of satellite-borne systems will require transceivers and processors that can handle several Gb/s of data. Optical interconnects have been praised for both their speed and functionality with hopes that light can relieve the electrical bottleneck predicted for the near future. Optoelectronic interconnects provide a factor of ten improvement over electrical interconnects.

Proof of Concept of Impact Detection in Composites Using Fiber Bragg Grating Arrays

PubMed Central

Gomez, Javier; Jorge, Iagoba; Durana, Gaizka; Arrue, Jon; Zubia, Joseba; Aranguren, Gerardo; Montero, Ander; López, Ion

2013-01-01

Impact detection in aeronautical structures allows predicting their future reliability and performance. An impact can produce microscopic fissures that could evolve into fractures or even the total collapse of the structure, so it is important to know the location and severity of each impact. For this purpose, optical fibers with Bragg gratings are used to analyze each impact and the vibrations generated by them. In this paper it is proven that optical fibers with Bragg gratings can be used to detect impacts, and also that a high-frequency interrogator is necessary to collect valuable information about the impacts. The use of two interrogators constitutes the main novelty of this paper. PMID:24021969

Development of a Computer-Controlled Polishing Process for X-Ray Optics

NASA Technical Reports Server (NTRS)

Khan, Gufran S.; Gubarev, Mikhail; Arnold, William; Ramsey, Brian

2009-01-01

The future X-ray observatory missions require grazing-incidence x-ray optics with angular resolution of < 5 arcsec half-power diameter. The achievable resolution depends ultimately on the quality of polished mandrels from which the shells are replicated. With an aim to fabricate better shells, and reduce the cost/time of mandrel production, a computer-controlled polishing machine is developed for deterministic and localized polishing of mandrels. Cylindrical polishing software is also developed that predicts the surface residual errors under a given set of operating parameters and lap configuration. Design considerations of the polishing lap are discussed and the effects of nonconformance of the lap and the mandrel are presented.

The relationship between decorrelation time and sample thickness in acute rat brain tissue slices (Conference Presentation)

NASA Astrophysics Data System (ADS)

Brake, Joshua; Jang, Mooseok; Yang, Changhuei

2016-03-01

The optical opacity of biological tissue has long been a challenge in biomedical optics due to the strong scattering nature of tissue in the optical regime. While most conventional optical techniques attempt to gate out multiply scattered light and use only unscattered light, new approaches in the field of wavefront shaping exploit the time reversible symmetry of optical scattering in order to focus light inside or through scattering media. While these approaches have been demonstrated effectively on static samples, it has proven difficult to apply them to dynamic biological samples since even small changes in the relative positions of the scatterers within will cause the time symmetry that wavefront shaping relies upon to decorrelate. In this paper we investigate the decorrelation curves of acute rat brain slices for thicknesses in the range 1-3 mm (1/e decorrelation time on the order of seconds) using multi-speckle diffusing wave spectroscopy (MSDWS) and compare the results with theoretical predictions. The results of this study demonstrate that the 1/L^2 relationship between decorrelation time and thickness predicted by diffusing wave spectroscopy provides a good rule of thumb for estimating how the decorrelation of a sample will change with increasing thickness. Understanding this relationship will provide insight to guide the future development of biophotonic wavefront shaping tools by giving an estimate of how fast wavefront shaping systems need to operate to overcome the dynamic nature of biological samples.

Test of Special Relativity Using a Fiber Network of Optical Clocks.

PubMed

Delva, P; Lodewyck, J; Bilicki, S; Bookjans, E; Vallet, G; Le Targat, R; Pottie, P-E; Guerlin, C; Meynadier, F; Le Poncin-Lafitte, C; Lopez, O; Amy-Klein, A; Lee, W-K; Quintin, N; Lisdat, C; Al-Masoudi, A; Dörscher, S; Grebing, C; Grosche, G; Kuhl, A; Raupach, S; Sterr, U; Hill, I R; Hobson, R; Bowden, W; Kronjäger, J; Marra, G; Rolland, A; Baynes, F N; Margolis, H S; Gill, P

2017-06-02

Phase compensated optical fiber links enable high accuracy atomic clocks separated by thousands of kilometers to be compared with unprecedented statistical resolution. By searching for a daily variation of the frequency difference between four strontium optical lattice clocks in different locations throughout Europe connected by such links, we improve upon previous tests of time dilation predicted by special relativity. We obtain a constraint on the Robertson-Mansouri-Sexl parameter |α|≲1.1×10^{-8}, quantifying a violation of time dilation, thus improving by a factor of around 2 the best known constraint obtained with Ives-Stilwell type experiments, and by 2 orders of magnitude the best constraint obtained by comparing atomic clocks. This work is the first of a new generation of tests of fundamental physics using optical clocks and fiber links. As clocks improve, and as fiber links are routinely operated, we expect that the tests initiated in this Letter will improve by orders of magnitude in the near future.

Optical Properties and Aging of Gasochromic WO3

NASA Astrophysics Data System (ADS)

Ghosh, Rudresh; Baker, Matthew B.; Lopez, Rene

2009-03-01

WO3 as a possible optical gas sensor has gained increasing importance with H2 becoming a major fuel of the future. This has led to efforts to understand the theoretical and practical aspects of the gasochromic behavior of WO3. WO3 films were fabricated using pulsed laser deposition (PLD). Morphological and stoichiometric ratios of films obtained were observed as functions of deposition parameters. We present the optical constants induced by 2% H2:Ar in WO3 films. This allows us to obtain the limits of the gasochromic change in comparison to ion injection. It was found using Langmuir's adsorption equation that at low H2 concentrations a high sensitivity is predicted but the coloration could saturate at 57.9 % of the material's maximum ion adsorption. Poisoning of the films was also addressed by coating with a permeable polydimethylsiloxane layer. It is shown that gasochromic degradation is prevented thus eliminating common atmospheric gases as possible contaminants. Our studies suggest WO3 thin films as highly sensitive and stable optical hydrogen sensors. .

Optical Properties and Aging of Gasochromic WO3

NASA Astrophysics Data System (ADS)

Ghosh, Rudresh; Baker, Matthew B.; Lopez, Rene

2008-10-01

WO3 as a possible optical gas sensor has gained increasing importance with H2 becoming a major fuel of the future. This has led to efforts to understand the theoretical and practical aspects of the gasochromic behavior of WO3. WO3 films were fabricated using pulsed laser deposition (PLD). Morphological and stoichiometric ratios of films obtained were observed as functions of deposition parameters. We present the optical constants induced by 2% H2:Ar in WO3 films. This allows us to obtain the limits of the gasochromic change in comparison to ion injection. It was found using Langmuir's adsorption equation that at low H2 concentrations a high sensitivity is predicted but the coloration could saturate at 57.9 % of the material's maximum ion adsorption. Poisoning of the films was also addressed by coating with a permeable polydimethylsiloxane layer. It is shown that gasochromic degradation is prevented thus eliminating common atmospheric gases as possible contaminants. Our studies suggest WO3 thin films as highly sensitive and stable optical hydrogen sensors.

ACTRIS Aerosol, Clouds and Trace Gases Research Infrastructure

NASA Astrophysics Data System (ADS)

Pappalardo, Gelsomina

2018-04-01

The Aerosols, Clouds and Trace gases Research Infrastructure (ACTRIS) is a distributed infrastructure dedicated to high-quality observation of aerosols, clouds, trace gases and exploration of their interactions. It will deliver precision data, services and procedures regarding the 4D variability of clouds, short-lived atmospheric species and the physical, optical and chemical properties of aerosols to improve the current capacity to analyse, understand and predict past, current and future evolution of the atmospheric environment.

Development of Laser Beam Transmission Strategies for Future Ground-to-Space Optical Communications

NASA Technical Reports Server (NTRS)

Wilson, Keith E.; Kovalik, Joseph M.; Biswas, Abhijit; Roberts, William T.

2007-01-01

Optical communications is a key technology to meet the bandwidth expansion required in the global information grid. High bandwidth bi-directional links between sub-orbital platforms and ground and space terminals can provide a seamless interconnectivity for rapid return of critical data to analysts. The JPL Optical Communications Telescope Laboratory (OCTL) is located in Wrightwood California at an altitude of 2.2.km. This 200 sq-m facility houses a state-of- the-art 1-m telescope and is used to develop operational strategies for ground-to-space laser beam propagation that include safe beam transmission through navigable air space, adaptive optics correction and multi-beam scintillation mitigation, and line of sight optical attenuation monitoring. JPL has received authorization from international satellite owners to transmit laser beams to more than twenty retro-reflecting satellites. This paper presents recent progress in the development of these operational strategies tested by narrow laser beam transmissions from the OCTL to retro-reflecting satellites. We present experimental results and compare our measurements with predicted performance for a variety of atmospheric conditions.

Modeling Photodisintegration-induced TeV Photon Emission from Low-luminosity Gamma-Ray Bursts

NASA Astrophysics Data System (ADS)

Liu, Xue-Wen; Wu, Xue-Feng; Lu, Tan

2012-05-01

Ultra-high-energy cosmic-ray heavy nuclei have recently been considered as originating from nearby low-luminosity gamma-ray bursts that are associated with Type Ibc supernovae. Unlike the power-law decay in long duration gamma-ray bursts, the light curve of these bursts exhibits complex UV/optical behavior: shock breakout dominated thermal radiation peaks at about 1 day, and, after that, nearly constant emission sustained by radioactive materials for tens of days. We show that the highly boosted heavy nuclei at PeV energy interacting with the UV/optical photon field will produce considerable TeV photons via the photodisintegration/photo-de-excitation process. It was later predicted that a thermal-like γ-ray spectrum peaks at about a few TeV, which may serve as evidence of nucleus acceleration. The future observations by the space telescope Fermi and by the ground atmospheric Cherenkov telescopes such as H.E.S.S., VERITAS, and MAGIC will shed light on this prediction.

Counter-propagating optical trapping system for size and refractive index measurement of microparticles.

PubMed

Flynn, Richard A; Shao, Bing; Chachisvilis, Mirianas; Ozkan, Mihrimah; Esener, Sadik C

2006-01-15

We propose and demonstrate a novel approach to measure the size and refractive index of microparticles based on two beam optical trapping, where forward scattered light is detected to give information about the particle. The counter-propagating optical trap measurement (COTM) system exploits the capability of optical traps to measure pico-Newton forces for microparticles' refractive index and size characterization. Different from the current best technique for microparticles' refractive index measurement, refractometry, a bulk technique requiring changing the fluid composition of the sample, our optical trap technique works with any transparent fluid and enables single particle analysis without the use of biological markers. A ray-optics model is used to explore the physical operation of the COTM system, predict system performance and aid system design. Experiments demonstrate the accuracy of refractive index measurement of Deltan=0.013 and size measurement of 3% of diameter with 2% standard deviation. Present performance is instrumentation limited, and a potential improvement by more than two orders of magnitude can be expected in the future. With further development in parallelism and miniaturization, the system offers advantages for cell manipulation and bioanalysis compatible with lab-on-a-chip systems.

Halo models of HI selected galaxies

NASA Astrophysics Data System (ADS)

Paul, Niladri; Choudhury, Tirthankar Roy; Paranjape, Aseem

2018-06-01

Modelling the distribution of neutral hydrogen (HI) in dark matter halos is important for studying galaxy evolution in the cosmological context. We use a novel approach to infer the HI-dark matter connection at the massive end (m_H{I} > 10^{9.8} M_{⊙}) from radio HI emission surveys, using optical properties of low-redshift galaxies as an intermediary. In particular, we use a previously calibrated optical HOD describing the luminosity- and colour-dependent clustering of SDSS galaxies and describe the HI content using a statistical scaling relation between the optical properties and HI mass. This allows us to compute the abundance and clustering properties of HI-selected galaxies and compare with data from the ALFALFA survey. We apply an MCMC-based statistical analysis to constrain the free parameters related to the scaling relation. The resulting best-fit scaling relation identifies massive HI galaxies primarily with optically faint blue centrals, consistent with expectations from galaxy formation models. We compare the Hi-stellar mass relation predicted by our model with independent observations from matched Hi-optical galaxy samples, finding reasonable agreement. As a further application, we make some preliminary forecasts for future observations of HI and optical galaxies in the expected overlap volume of SKA and Euclid/LSST.

Optical, analog and digital domain architectural considerations for visual communications

NASA Astrophysics Data System (ADS)

Metz, W. A.

2008-01-01

The end of the performance entitlement historically achieved by classic scaling of CMOS devices is within sight, driven ultimately by fundamental limits. Performance entitlements predicted by classic CMOS scaling have progressively failed to be realized in recent process generations due to excessive leakage, increasing interconnect delays and scaling of gate dielectrics. Prior to reaching fundamental limits, trends in technology, architecture and economics will pressure the industry to adopt new paradigms. A likely response is to repartition system functions away from digital implementations and into new architectures. Future architectures for visual communications will require extending the implementation into the optical and analog processing domains. The fundamental properties of these domains will in turn give rise to new architectural concepts. The limits of CMOS scaling and impact on architectures will be briefly reviewed. Alternative approaches in the optical, electronic and analog domains will then be examined for advantages, architectural impact and drawbacks.

NuMI Flux Predictions for NOvA and MINERvA

NASA Astrophysics Data System (ADS)

Aliaga Soplin, Leonidas; Nova Collaboration; Minerva Collaboration

2017-01-01

The determination of the neutrino flux in any conventional neutrino beam presents a challenge for the current and future short and long baseline neutrino experiments. The uncertainties associated with the production and attenuation of the hadrons in the beamline materials along with those associated with the beam optics have a big effect in the knowledge of the flux. For experiments like MINERvA and NOvA, understanding the flux is crucial since it enters directly into every neutrino-nucleus cross-section measurement. The majority of this work involves predicting the neutrino flux using dedicated hadron production measurements from hadron-nucleus collisions. The predictions at the MINERvA and NOvA near detectors are presented as well as the results of incorporating in-situ MINERvA data that can provide additional constraints. These results have been fully implemented in MINERvA and they are currently use for its cross-section analysis. The implementation for NoVA is underway. The procedure and conclusions of this work will have a big impact on future hadron production experiments and on determining the flux for the upcoming DUNE experiment.

SIMULATION OF ASTRONOMICAL IMAGES FROM OPTICAL SURVEY TELESCOPES USING A COMPREHENSIVE PHOTON MONTE CARLO APPROACH

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

Peterson, J. R.; Peng, E.; Ahmad, Z.

2015-05-15

We present a comprehensive methodology for the simulation of astronomical images from optical survey telescopes. We use a photon Monte Carlo approach to construct images by sampling photons from models of astronomical source populations, and then simulating those photons through the system as they interact with the atmosphere, telescope, and camera. We demonstrate that all physical effects for optical light that determine the shapes, locations, and brightnesses of individual stars and galaxies can be accurately represented in this formalism. By using large scale grid computing, modern processors, and an efficient implementation that can produce 400,000 photons s{sup −1}, we demonstratemore » that even very large optical surveys can be now be simulated. We demonstrate that we are able to (1) construct kilometer scale phase screens necessary for wide-field telescopes, (2) reproduce atmospheric point-spread function moments using a fast novel hybrid geometric/Fourier technique for non-diffraction limited telescopes, (3) accurately reproduce the expected spot diagrams for complex aspheric optical designs, and (4) recover system effective area predicted from analytic photometry integrals. This new code, the Photon Simulator (PhoSim), is publicly available. We have implemented the Large Synoptic Survey Telescope design, and it can be extended to other telescopes. We expect that because of the comprehensive physics implemented in PhoSim, it will be used by the community to plan future observations, interpret detailed existing observations, and quantify systematics related to various astronomical measurements. Future development and validation by comparisons with real data will continue to improve the fidelity and usability of the code.« less

Spinoff 2010

NASA Technical Reports Server (NTRS)

2010-01-01

Topics covered include: Burnishing Techniques Strengthen Hip Implants; Signal Processing Methods Monitor Cranial Pressure; Ultraviolet-Blocking Lenses Protect, Enhance Vision; Hyperspectral Systems Increase Imaging Capabilities; Programs Model the Future of Air Traffic Management; Tail Rotor Airfoils Stabilize Helicopters, Reduce Noise; Personal Aircraft Point to the Future of Transportation; Ducted Fan Designs Lead to Potential New Vehicles; Winglets Save Billions of Dollars in Fuel Costs; Sensor Systems Collect Critical Aerodynamics Data; Coatings Extend Life of Engines and Infrastructure; Radiometers Optimize Local Weather Prediction; Energy-Efficient Systems Eliminate Icing Danger for UAVs; Rocket-Powered Parachutes Rescue Entire Planes; Technologies Advance UAVs for Science, Military; Inflatable Antennas Support Emergency Communication; Smart Sensors Assess Structural Health; Hand-Held Devices Detect Explosives and Chemical Agents; Terahertz Tools Advance Imaging for Security, Industry; LED Systems Target Plant Growth; Aerogels Insulate Against Extreme Temperatures; Image Sensors Enhance Camera Technologies; Lightweight Material Patches Allow for Quick Repairs; Nanomaterials Transform Hairstyling Tools; Do-It-Yourself Additives Recharge Auto Air Conditioning; Systems Analyze Water Quality in Real Time; Compact Radiometers Expand Climate Knowledge; Energy Servers Deliver Clean, Affordable Power; Solutions Remediate Contaminated Groundwater; Bacteria Provide Cleanup of Oil Spills, Wastewater; Reflective Coatings Protect People and Animals; Innovative Techniques Simplify Vibration Analysis; Modeling Tools Predict Flow in Fluid Dynamics; Verification Tools Secure Online Shopping, Banking; Toolsets Maintain Health of Complex Systems; Framework Resources Multiply Computing Power; Tools Automate Spacecraft Testing, Operation; GPS Software Packages Deliver Positioning Solutions; Solid-State Recorders Enhance Scientific Data Collection; Computer Models Simulate Fine Particle Dispersion; Composite Sandwich Technologies Lighten Components; Cameras Reveal Elements in the Short Wave Infrared; Deformable Mirrors Correct Optical Distortions; Stitching Techniques Advance Optics Manufacturing; Compact, Robust Chips Integrate Optical Functions; Fuel Cell Stations Automate Processes, Catalyst Testing; Onboard Systems Record Unique Videos of Space Missions; Space Research Results Purify Semiconductor Materials; and Toolkits Control Motion of Complex Robotics.

Quasi-Optical Filter Development and Characterization for Far-IR Astronomical Applications

NASA Astrophysics Data System (ADS)

Stewart, Kenneth

Mid-infrared through microwave filters, beamsplitters, and polarizers are a crucial supporting technology for NASA’s space astronomy, astrophysics, and earth science programs. Building upon our successful production of mid-infrared, far-infrared, millimeter, and microwave bandpass and lowpass filters, we propose to investigate aspects of their optical performance that are still not well understood and have yet to be addressed by other researchers. Specifically, we wish to understand and mitigate unexplained high-frequency leaks found to degrade or invalidate spectroscopic data from flight instruments such as Herschel/PACS, SHARC II, GISMO, and ACT, but not predicted by numerical simulations. A complete understanding will improve accuracy and sensitivity, and will enable the mass and volume of cryogenic baffling to be appropriately matched to the physically achievable quasioptical filter response, thereby reducing the cost of future far-infrared missions. The development and experimental validation of this modeling capability will enable optimization of system performance as well as reduce risks to the schedule and end science products for all future space and suborbital missions that use quasioptical filters. The outcome of this work will be critical in achieving the exacting background-limited bolometric detector performance specifications of future far-infrared and submillimeter space instruments. This program will allow us to apply our unique in-house numerical simulation software and develop enhanced layer alignment, filter fabrication, and testing techniques for the first time to address these issues: (1) enhance filter performance, (2) simplify the optical architecture of future instruments by improving our understanding of high-frequency leaks, and (3) produce filters which minimize or eliminate these important effects. With our state-ofthe-art modeling, fabrication, and testing facilities and expertise, established in previous projects, we are uniquely positioned to tackle this development.

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.

On the development status of high performance silicon pore optics for future x-ray telescopes

NASA Astrophysics Data System (ADS)

Kraft, Stefan; Collon, M.; Günther, R.; Partapsing, R.; Beijersbergen, M.; Bavdaz, M.; Lumb, D.; Peacock, A.; Wallace, K.

2017-11-01

Silicon pore optics have been proposed earlier as modular optical X-ray units in large Wolter-I telescopes that would match effective area and resolution requirements imposed by missions such as XEUS. Since then the optics have been developed further and the feasibility of the production of high-performance pore optics has been demonstrated. Optimisation of both the production and the assembly process allowed the generation of optics with larger areas with improved imaging performance. Silicon pore optics can now be manufactured with properties required for future X-ray telescopes. A suitable design that allows the implementation of pore optics into X-ray Optical Units in Wolter-I configuration was recently derived including an appropriate telescope mounting structure with interfaces for the individual components. The development status, the achieved performance and the requirements regarding future mirror production, optics assembly and related metrology for its characterisation are presented.

Evolution of ring-field systems in microlithography

NASA Astrophysics Data System (ADS)

Williamson, David M.

1998-09-01

Offner's ring-field all-reflecting triplet was the first successful projection system used in microlithography. It evolved over several generations, increasing NA and field size, reducing the feature sizes printed from three down to one micron. Because of its relative simplicity, large field size and broad spectral bandwidth it became the dominant optical design used in microlithography until the early 1980's, when the demise of optical lithography was predicted. Rumours of the death of optics turned out to be exaggerated; what happened instead was a metamorphosis to more complex optical designs. A reduction ring-field system was developed, but the inevitable loss of concentricity led to a dramatic increase in complexity. Higher NA reduction projection optics have therefore been full-field, either all-refracting or catadioptric using a beamsplitter and a single mirror. At the present time, the terminal illness of optical lithography is once again being prognosed, but now at 0.1 micro feature sizes early in the next millenium. If optics has a future beyond that, it lies at wavelengths below the practical transmission cut-off of all refracting materials. Scanning all-reflecting ring-field systems are therefore poised for a resurgence, based on their well-established advantage of rotational symmetry and consequent small aberration variations over a small, annular field. This paper explores some such designs that potentially could take optical lithography down to the region of 0.025 micron features.

Design of stabilized platforms for deep space optical communications (DSOC)

NASA Astrophysics Data System (ADS)

Jacka, N.; Walter, R.; Laughlin, D.; McNally, J.

2017-02-01

Numerous Deep Space Optical Communications (DSOC) demonstrations are planned by NASA to provide the basis for future implementation of optical communications links in planetary science missions and eventually manned missions to Mars. There is a need for a simple, robust precision optical stabilization concept for long-range free space optical communications applications suitable for optical apertures and masses larger than the current state of the art. We developed a stabilization concept by exploiting the ultra-low noise and wide bandwidth of ATA-proprietary Magnetohydrodynamic (MHD) angular rate sensors and building on prior practices of flexure-based isolation. We detail a stabilization approach tailored for deep space optical communications, and present an innovative prototype design and test results. Our prototype system provides sub-micro radian stabilization for a deep space optical link such as NASA's integrated Radio frequency and Optical Communications (iROC) and NASA's DSOC programs. Initial test results and simulations suggest that >40 dB broadband jitter rejection is possible without placing unrealistic expectations on the control loop bandwidth and flexure isolation frequency. This approach offers a simple, robust method for platform stabilization without requiring a gravity offload apparatus for ground testing or launch locks to survive a typical launch environment. This paper reviews alternative stabilization concepts, their advantages and disadvantages, as well as, their applicability to various optical communications applications. We present results from testing that subjected the prototype system to realistic spacecraft base motion and confirmed predicted sub-micro radian stabilization performance with a realistic 20-cm aperture.

Fiber Pulling Apparatus

NASA Technical Reports Server (NTRS)

Workman, Gary L.; Smith, Guy A.; OBrien, Sue; Adcock, Leonard

1998-01-01

The fiber optics industry has grown into a multi-billion marketplace that will continue to grow into the 21st century. Optical fiber communications is currently dominated by silica glass technology. Successful efforts to improve upon the low loss transmission characteristics of silica fibers have propelled the technology into the forefront of the communications industry. However, reaching the theoretical transmission capability of silica fiber through improved processing has still left a few application areas in which other fiber systems can provide an influential role due to specific characteristics of high theoretical transmission in the 2 - 3 micron wavelength region. One of the other major materials used for optical fibers is the systems based upon Heavy Metal Fluoride Glass (HMFG). Commercial interest is driven primarily by the potential for low loss repeaterless infrared fibers. An example of the major communications marketplace which would benefit from the long distance repeaterless capability of infrared fibers is the submarine cables which link the continents. When considering commercial interests, optical fiber systems provide a healthy industrial position which continues to expand. Major investments in the systems used for optical fiber communications have continued to increase each year and are predicted to continue well into the next century. Estimates of 8.5% compounded annually are predicted through 1999 for the North American market and 1 1 % worldwide. The growth for the optical fiber cable itself is expected to continue between 44 and 50 per cent of the optical fiber communications budget through 1999. The total budget in 1999 world-wide is expected to be in the neighborhood of $9 billion. Another survey predicts that long haul telecommunications represents 15% of a world-wide fiber optics market in 1998. The actual amount allotted to cable was not specified. However, another market research had predicted that the cable costs alone represents more than 50% of the total budget each year through 1998. A newly emerging activity is the commercial development of doped optical fibers which can be pumped by laser diodes to provide amplification of the communication signals. This technology is newly emerging and will be developed for commercial interests in the United States by Galileo Electro-optical Incorporated in Sturbridge, MA on a license from British Telecom. Long repeaterless communication links provide the biggest stimulus for this technology. As an example of the of the revenues involved in the optical fiber communications 3 industry, the current trade journal lists that for the fiscal years, 1991 - 1994, 185 separate undersea links were established. In addition, another 105 links are planned through 1998. The distribution of revenues involved in the undersea installations is roughly $8.5 billion through 1993 and another $13 billion planned through 1998. A large portion of the future activity (34%) is planned for Southeast Asia and the Pacific Region. Other examples of the commercial utility of optical fiber networks is given in a recent scientific symposium in which the outlook for HMFG infrared fiber was determined to be very bright.Another area of interest lies in the use of fiber optics for laser surgery delivery systems.

The measurement of ultrasound scattering from individual micron-sized objects and its application in single cell scattering.

PubMed

Falou, Omar; Rui, Min; El Kaffas, Ahmed; Kumaradas, J Carl; Kolios, Michael C

2010-08-01

The measurement of the ultrasound backscatter from individual micron-sized objects such as cells is required for various applications such as tissue characterization. However, performing such a measurement remains a challenge. For example, the presence of air bubbles in a suspension of cells during the measurements may lead to the incorrect interpretation of the acoustic signals. This work introduces a technique for measuring the ultrasound backscatter from individual micron-sized objects by combining a microinjection system with a co-registered optical microscope and an ultrasound imaging device. This allowed the measurement of the ultrasound backscatter response from a single object under optical microscope guidance. The optical and ultrasonic data were used to determine the size of the object and to deduce its backscatter responses, respectively. In order to calibrate the system, the backscatter frequency responses from polystyrene microspheres were measured and compared to theoretical predictions. A very good agreement was found between the measured backscatter responses of individual microspheres and theoretical predictions of an elastic sphere. The backscatter responses from single OCI-AML-5 cells were also investigated. It was found that the backscatter responses from AML cells are best modeled using the fluid sphere model. The advantages, limitations, and future applications of the developed technique are discussed.

Optical Variability and Bottom Classification in Turbid Waters: HyMOM Predictions of the Light Field in Ports and Beneath Ship Hulls

DTIC Science & Technology

2006-09-30

dealing with the bleaching of corals and foraminifera and the photosynthesis of benthic plants. OBJECTIVES The initial objective of this work...of the structural light field around coral heads and other vertical structures should be included in future studies of bleaching of coral and... coral bleaching –Perceptibility problem begun for AUV @2m and @8m above 10m bottom –Higher resolution and higher-speed calculations (e.g. more

Integrated Modeling of Optical Systems (IMOS): An Assessment and Future Directions

NASA Technical Reports Server (NTRS)

Moore, Gregory; Broduer, Steve (Technical Monitor)

2001-01-01

Integrated Modeling of Optical Systems (IMOS) is a finite element-based code combining structural, thermal, and optical ray-tracing capabilities in a single environment for analysis of space-based optical systems. We'll present some recent examples of IMOS usage and discuss future development directions. Due to increasing model sizes and a greater emphasis on multidisciplinary analysis and design, much of the anticipated future work will be in the areas of improved architecture, numerics, and overall performance and analysis integration.

Using radiance predicted by the P3 approximation in a spherical geometry to predict tissue optical properties

NASA Astrophysics Data System (ADS)

Dickey, Dwayne J.; Moore, Ronald B.; Tulip, John

2001-01-01

For photodynamic therapy of solid tumors, such as prostatic carcinoma, to be achieved, an accurate model to predict tissue parameters and light dose must be found. Presently, most analytical light dosimetry models are fluence based and are not clinically viable for tissue characterization. Other methods of predicting optical properties, such as Monet Carlo, are accurate but far too time consuming for clinical application. However, radiance predicted by the P3-Approximation, an anaylitical solution to the transport equation, may be a viable and accurate alternative. The P3-Approximation accurately predicts optical parameters in intralipid/methylene blue based phantoms in a spherical geometry. The optical parameters furnished by the radiance, when introduced into fluence predicted by both P3- Approximation and Grosjean Theory, correlate well with experimental data. The P3-Approximation also predicts the optical properties of prostate tissue, agreeing with documented optical parameters. The P3-Approximation could be the clinical tool necessary to facilitate PDT of solid tumors because of the limited number of invasive measurements required and the speed in which accurate calculations can be performed.

Constraining primordial non-Gaussianity with bispectrum and power spectrum from upcoming optical and radio surveys

NASA Astrophysics Data System (ADS)

Karagiannis, Dionysios; Lazanu, Andrei; Liguori, Michele; Raccanelli, Alvise; Bartolo, Nicola; Verde, Licia

2018-07-01

We forecast constraints on primordial non-Gaussianity (PNG) and bias parameters from measurements of galaxy power spectrum and bispectrum in future radio continuum and optical surveys. In the galaxy bispectrum, we consider a comprehensive list of effects, including the bias expansion for non-Gaussian initial conditions up to second order, redshift space distortions, redshift uncertainties and theoretical errors. These effects are all combined in a single PNG forecast for the first time. Moreover, we improve the bispectrum modelling over previous forecasts, by accounting for trispectrum contributions. All effects have an impact on final predicted bounds, which varies with the type of survey. We find that the bispectrum can lead to improvements up to a factor ˜5 over bounds based on the power spectrum alone, leading to significantly better constraints for local-type PNG, with respect to current limits from Planck. Future radio and photometric surveys could obtain a measurement error of σ (f_{NL}^{loc}) ≈ 0.2. In the case of equilateral PNG, galaxy bispectrum can improve upon present bounds only if significant improvements in the redshift determinations of future, large volume, photometric or radio surveys could be achieved. For orthogonal non-Gaussianity, expected constraints are generally comparable to current ones.

Constraining Primordial non-Gaussianity with Bispectrum and Power Spectum from Upcoming Optical and Radio Surveys

NASA Astrophysics Data System (ADS)

Karagiannis, Dionysios; Lazanu, Andrei; Liguori, Michele; Raccanelli, Alvise; Bartolo, Nicola; Verde, Licia

2018-04-01

We forecast constraints on primordial non-Gaussianity (PNG) and bias parameters from measurements of galaxy power spectrum and bispectrum in future radio continuum and optical surveys. In the galaxy bispectrum, we consider a comprehensive list of effects, including the bias expansion for non-Gaussian initial conditions up to second order, redshift space distortions, redshift uncertainties and theoretical errors. These effects are all combined in a single PNG forecast for the first time. Moreover, we improve the bispectrum modelling over previous forecasts, by accounting for trispectrum contributions. All effects have an impact on final predicted bounds, which varies with the type of survey. We find that the bispectrum can lead to improvements up to a factor ˜5 over bounds based on the power spectrum alone, leading to significantly better constraints for local-type PNG, with respect to current limits from Planck. Future radio and photometric surveys could obtain a measurement error of σ (f_{NL}^{loc}) ≈ 0.2. In the case of equilateral PNG, galaxy bispectrum can improve upon present bounds only if significant improvements in the redshift determinations of future, large volume, photometric or radio surveys could be achieved. For orthogonal non-Gaussianity, expected constraints are generally comparable to current ones.

Free space optics: a viable last-mile alternative

NASA Astrophysics Data System (ADS)

Willebrand, Heinz A.; Clark, Gerald R.

2001-10-01

This paper explores Free Space Optics (FSO) as an access technology in the last mile of metropolitan area networks (MANs). These networks are based in part on fiber-optic telecommunications infrastructure, including network architectures of Synchronous Optical Network (commonly referred to as SONET), the North American standard for synchronous data transmission; and Synchronous Digital Hierarchy (commonly referred to as SDH), the international standard and equivalent of SONET. Several converging forces have moved FSO beyond a niche technology for use only in local area networks (LANs) as a bridge connecting two facilities. FSO now allows service providers to cost effectively provide optical bandwidth for access networks and accelerate the extension of metro optical networks bridging what has been termed by industry experts as the optical dead zone. The optical dead zone refers to both the slowdown in capital investment in the short-term future and the actual connectivity gap that exists today between core metro optical networks and the access optical networks. Service providers have built extensive core and minimal metro networks but have not yet provided optical bandwidth to the access market largely due to the non-compelling economics to bridge the dead zone with fiber. Historically, such infrastructure build-out slowdowns have been blamed on a combination of economics, time-to-market constraints and limited technology options. However, new technology developments and market acceptance of FSO give service providers a new cost-effective alternative to provide high-bandwidth services with optical bandwidth in the access networks. Merrill Lynch predicts FSO will grow into a $2 billion market by 2005. The drivers for this market are a mere 5%- 6% penetration of fiber to business buildings; cost effective solution versus RF or fiber; and significant capacity which can only be matched by a physical fiber link, Merrill Lynch reports. This paper will describe FSO technology, its capabilities and its limitations. The paper will investigate how FSO technology has evolved to its current stage for deployment in MANs, LANs, wireless backhaul and metropolitan network extensions - applications that fall within the category of last mile. The paper will address the market, drivers and the adoption of FSO, plus provide a projection of future FSO technology, based on today's product roadmaps. The paper concludes with a summary of findings and recommendations.

Optical Region Spectrophotometry: Past and Present

NASA Astrophysics Data System (ADS)

Adelman, Saul J.

In the 1960s and 1970s optical region spectrophotometry achieved the status of a major tool in stellar research. New instrumentation, rotating grating scanners using photomultiplier tubes as detectors, and improved absolute calibrations of Vega made this possible. After this period the use of this technique declined to its near demise at present. The use of Vega as the primary standard has been both a blessing as it is so bright and a curse especially as modeling it correctly requires treating it as a fast rotating star seen nearly pole-on. It may be better to use several stars to define any future absolute calibration. With absolutely calibrated fluxes and Balmer profiles, often Hγ, investigators used the predictions of model atmospheres to find both the effective temperatures and the surface gravities of stars. The fluxes were photometrically calibrated low dispersion spectra with a typical resolution of order 25 Å. A typical data set consisted of 10-15 values covering most of the optical spectral region. At present two instrumental projects ACCESS and the ASTRA Spectrophotometer promise, respectively, a new substantially improved absolute calibration of the optical fluxes of several targets and the availability of a considerable amount of well-calibrated optical flux data for use in studies concerned with stellar properties. They jointly promise to revive optical region spectrophotometric studies.

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.

The JPL optical communications telescope laboratory (OCTL) test bed for the future optical Deep Space Network

NASA Technical Reports Server (NTRS)

Wilson, K. E.; Page, N.; Wu, J.; Srinivasan, M.

2003-01-01

Relative to RF, the lower power-consumption and lower mass of high bandwidth optical telecommunications make this technology extremely attractive for returning data from future NASA/JPL deep space probes.

Prediction of TARANIS Observations of TGF's and Optical Emissions from Red Sprites

NASA Astrophysics Data System (ADS)

Nelson, M. A.

2006-12-01

TARANIS (Tool for the Analysis of Radiation from Lightning and Sprites) is a French (CNES, Centre National D'Etudes Spatiales) micro-satellite that is scheduled for launch in 2009. This will be the first satellite that will measure coincident gamma-rays and optical emissions from atmospheric discharges. These measurements will provide important clues concerning the physics of discharges that produce gamma-rays and will provide more definitive evidence of the role of conventional breakdown versus runaway breakdown than is currently available. While a variety of discharges may be associated with Transient Gamma Ray Flashes (TGF's), this study will focus on emissions expected from red sprites. Future studies will focus on other types of discharges (for example, gigantic jets or blue jets) to see whether they should produce detectable signal levels at both gamma-ray and optical frequencies. The source of terrestrial TGF's is a matter of debate at this time. Many experts in the field have interpreted the data associated with the RHESSI (Reuven Ramaty High Energy Solar Spectroscopic Imager) satellite to be indicative that the discharges associated with terrestrial gamma-rays are not associated with sprites. However, RHESSI was not designed for the purpose of collecting gamma-ray measurements from terrestrial discharges; does not possess a coincident optical measurement capability; and must average data over many events to predict a spectrum. We will present a statistical analysis of the relative efficiencies of the RHESSI and TARANIS satellite designs for the detection of TGF's associated with sprites. We will show results from a fully 2-D electromagnetic model (UNIMAX, the Unified Maxwell code) and an optical model (POEM, the Physics Based Optical Emission Model) to demonstrate the level of agreement between the simulations and the gamma-ray spectrum measurements and optical measurements (camera, photometer, and spectral measurements) for several different classes of discharges (halos, streamers, and runaway breakdown.) We will distinguish which measurements and model results are indicative of conventional breakdown and which are indicative of runaway breakdown.

Identifying OH Imposters in the ALFALFA Neutral Hydrogen Survey

NASA Astrophysics Data System (ADS)

Suess, Katherine A.; Darling, Jeremy; Haynes, Martha P.; Giovanelli, Riccardo

2016-06-01

OH megamasers (OHMs) are rare, luminous molecular masers that are typically observed in (ultra) luminous infrared galaxies and serve as markers of major galaxy mergers. In blind emission line surveys such as the Arecibo Legacy Fast Arecibo L-Band Feed Array (ALFALFA) survey for neutral hydrogen (H I), OHMs at z ˜ 0.2 can mimic z ˜ 0.05 H I lines. We present the results of optical spectroscopy of ambiguous H I detections in the ALFALFA 40 per cent data release detected by the Wide Field Infrared Survey Explorer (WISE) but with uncertain optical counterparts. The optical redshifts, obtained from observations at the Apache Point Observatory, revealed five new OHMs and identified 129 H I optical counterparts. 60 candidates remain ambiguous. The new OHMs are the first detected in a blind spectral line survey. The number of OHMs in ALFALFA is consistent with predictions from the OH luminosity function. Additionally, the mid-infrared magnitudes and colours of the OHM host galaxies found in a blind survey do not seem to differ from those found in previous targeted surveys. This validates the methods used in previous IR-selected OHM surveys and indicates there is no previously unknown OHM-producing population at z ˜ 0.2. We also provide a method for future surveys to separate OH megamasers from 99 per cent of H I line emitters without optical spectroscopy by using WISE infrared colours and magnitudes. Since the fraction of OHMs found in flux-limited H I surveys is expected to increase with the survey's redshift, this selection method can be applied to future flux-limited high-redshift hydrogen surveys.

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.

Laser communication experiments between Sota and Meo optical ground station

NASA Astrophysics Data System (ADS)

Artaud, G.,; Issler, J.-L.; Védrenne, N.; Robert, C.; Petit, C.; Samain, E.; Phung, D.-H.; Maurice, N.; Toyoshima, M.; Kolev, D.

2017-09-01

Optical transmissions between earth and space have been identified as key technologies for future high data rate transmissions between satellites and ground. CNES is investigating the use of optics both for High data rate direct to Earth transfer from observation satellites in LEO, and for future telecommunications applications using optics for the high capacity Gateway link.

Active optics as enabling technology for future large missions: current developments for astronomy and Earth observation at ESA

NASA Astrophysics Data System (ADS)

Hallibert, Pascal

2017-09-01

In recent years, a trend for higher resolution has increased the entrance apertures of future optical payloads for both Astronomy and Earth Observation most demanding applications, resulting in new opto-mechanical challenges for future systems based on either monolithic or segmented large primary mirrors. Whether easing feasibility and schedule impact of tight manufacturing and integration constraints or correcting mission-critical in-orbit and commissioning effects, Active Optics constitutes an enabling technology for future large optical space instruments at ESA and needs to reach the necessary maturity in time for future mission selection and implementation. We present here a complete updated overview of our current R and D activities in this field, ranging from deformable space-compatible components to full correction chains including wavefront sensing as well as control and correction algorithms. We share as well our perspectives on the way-forward to technological maturity and implementation within future missions.

Gamma rays, X-rays, and optical light from the cobalt and the neutron star in SN 1987A

NASA Technical Reports Server (NTRS)

Kumagai, Shiomi; Shigeyama, Toshikazu; Nomoto, Ken'ichi; Itoh, Masayuki; Nishimura, Jun

1989-01-01

Recent developments in modeling the X-ray and gamma-ray emission from SN 1987A are discussed by taking into account both the decaying cobalt and the buried neutron star. The light curve and the spectra evolution of X-rays and gamma-rays are well modeled up to day of about 300 if mixing of Co-56 into hydrogen-rich envelope is assumed. However, the 16-28 keV flux observed by Ginga declines very slowly, whereas the spherical mixing model predicts that the flux should have decreased by a large factor at t greater than 300d. It is shown that this problem can be solved if the photoelectric absorption of X-rays is effectively reduced as a result of the formation of chemically inhomogeneous clumps. Based on the adopted hydrodynamical model and the abundance distribution, predictions are offered for future optical, X-ray, and gamma-ray light curves by taking into account other radioactive sources and various types of the central source, e.g., a buried neutron star accreting the reinfalling material or an isolated pulsar.

Fiber optic interconnect and optoelectronic packaging challenges for future generation avionics

NASA Astrophysics Data System (ADS)

Beranek, Mark W.

2007-02-01

Forecasting avionics industry fiber optic interconnect and optoelectronic packaging challenges that lie ahead first requires an assumption that military avionics architectures will evolve from today's centralized/unified concept based on gigabit laser, optical-to-electrical-to-optical switching and optical backplane technology, to a future federated/distributed or centralized/unified concept based on gigabit tunable laser, electro-optical switch and add-drop wavelength division multiplexing (WDM) technology. The requirement to incorporate avionics optical built-in test (BIT) in military avionics fiber optic systems is also assumed to be correct. Taking these assumptions further indicates that future avionics systems engineering will use WDM technology combined with photonic circuit integration and advanced packaging to form the technical basis of the next generation military avionics onboard local area network (LAN). Following this theme, fiber optic cable plants will evolve from today's multimode interconnect solution to a single mode interconnect solution that is highly installable, maintainable, reliable and supportable. Ultimately optical BIT for fiber optic fault detection and isolation will be incorporated as an integral part of a total WDM-based avionics LAN solution. Cost-efficient single mode active and passive photonic component integration and packaging integration is needed to enable reliable operation in the harsh military avionics application environment. Rugged multimode fiber-based transmitters and receivers (transceivers) with in-package optical BIT capability are also needed to enable fully BIT capable single-wavelength fiber optic links on both legacy and future aerospace platforms.

The Effect of Asymmetric Mechanical and Thermal Loading on Membrane Wrinkling

NASA Technical Reports Server (NTRS)

Blandino, Joseph R.; Johnston, John D.; Miles, Jonathan J.; Dharamsi, Urmil K.; Brodeur, Stephen J. (Technical Monitor)

2002-01-01

Large, tensioned membranes are being considered for future gossamer spacecraft systems. Examples include sunshields, solar sails, and membrane optics. In many. cases a relatively flat membrane with minimal wrinkling is desired. Developing methods to predict and measure membrane wrinkling is important to the future development of gossamer spacecraft. Numerical and experimental data are presented for a 0.5 m square, tensioned membrane. The membrane is subjected to symmetric and asymmetric mechanical loading. Data are also presented for a symmetrically loaded membrane subjected to spot heating in the center. The numerical model shows good agreement with the experiment for wrinkle angle data. There is. also reasonable agreement for the wrinkled area for both isothermal and elevated temperature tests.

Magnetic, electronic and optical properties of different graphene, BN and BC2N nanoribbons

NASA Astrophysics Data System (ADS)

Guerra, T.; Leite, L.; Azevedo, S.; de Lima Bernardo, B.

2017-04-01

Graphene nanoribbons are predicted to be essential components in future nanoelectronics. The size, edge type, form, arrangement of atoms and width of nanoribbons drastically change their properties. However, magnetic, electronic and optical properties of armchair, chevron and sawtooth of graphene, BN and BC2N nanoribbons are not fully understood so far. Here, we make use of first-principles calculations based on the density functional theory (DFT) to investigate the structural, magnetic, electronic and optical properties of nanoribbons of graphene, boron nitride and BC2N with armchair edge, chevron-type and sawtooth forms. The lowest formation energies were found for the armchair and chevron nanoribbons of graphene and boron nitride. We have shown that the imbalance of carbon atoms between different sublattices generates a net magnetic moment. Chevron-type nanoribbons of BC2N and graphene showed a band gap comparable with silicon, and a high light absorption in the visible spectrum when compared to the other configurations.

Picosecond pulses from wavelength-swept continuous-wave Fourier domain mode-locked lasers.

PubMed

Eigenwillig, Christoph M; Wieser, Wolfgang; Todor, Sebastian; Biedermann, Benjamin R; Klein, Thomas; Jirauschek, Christian; Huber, Robert

2013-01-01

Ultrafast lasers have a crucial function in many fields of science; however, up to now, high-energy pulses directly from compact, efficient and low-power semiconductor lasers are not available. Therefore, we introduce a new approach based on temporal compression of the continuous-wave, wavelength-swept output of Fourier domain mode-locked lasers, where a narrowband optical filter is tuned synchronously to the round-trip time of light in a kilometre-long laser cavity. So far, these rapidly swept lasers enabled orders-of-magnitude speed increase in optical coherence tomography. Here we report on the generation of ~60-70 ps pulses at 390 kHz repetition rate. As energy is stored optically in the long-fibre delay line and not as population inversion in the laser-gain medium, high-energy pulses can now be generated directly from a low-power, compact semiconductor-based oscillator. Our theory predicts subpicosecond pulses with this new technique in the future.

Picosecond pulses from wavelength-swept continuous-wave Fourier domain mode-locked lasers

NASA Astrophysics Data System (ADS)

Eigenwillig, Christoph M.; Wieser, Wolfgang; Todor, Sebastian; Biedermann, Benjamin R.; Klein, Thomas; Jirauschek, Christian; Huber, Robert

2013-05-01

Ultrafast lasers have a crucial function in many fields of science; however, up to now, high-energy pulses directly from compact, efficient and low-power semiconductor lasers are not available. Therefore, we introduce a new approach based on temporal compression of the continuous-wave, wavelength-swept output of Fourier domain mode-locked lasers, where a narrowband optical filter is tuned synchronously to the round-trip time of light in a kilometre-long laser cavity. So far, these rapidly swept lasers enabled orders-of-magnitude speed increase in optical coherence tomography. Here we report on the generation of ~60-70 ps pulses at 390 kHz repetition rate. As energy is stored optically in the long-fibre delay line and not as population inversion in the laser-gain medium, high-energy pulses can now be generated directly from a low-power, compact semiconductor-based oscillator. Our theory predicts subpicosecond pulses with this new technique in the future.

Optical critical dimension metrology for directed self-assembly assisted contact hole shrink

NASA Astrophysics Data System (ADS)

Dixit, Dhairya; Green, Avery; Hosler, Erik R.; Kamineni, Vimal; Preil, Moshe E.; Keller, Nick; Race, Joseph; Chun, Jun Sung; O'Sullivan, Michael; Khare, Prasanna; Montgomery, Warren; Diebold, Alain C.

2016-01-01

Directed self-assembly (DSA) is a potential patterning solution for future generations of integrated circuits. Its main advantages are high pattern resolution (˜10 nm), high throughput, no requirement of high-resolution mask, and compatibility with standard fab-equipment and processes. The application of Mueller matrix (MM) spectroscopic ellipsometry-based scatterometry to optically characterize DSA patterned contact hole structures fabricated with phase-separated polystyrene-b-polymethylmethacrylate (PS-b-PMMA) is described. A regression-based approach is used to calculate the guide critical dimension (CD), DSA CD, height of the PS column, thicknesses of underlying layers, and contact edge roughness of the post PMMA etch DSA contact hole sample. Scanning electron microscopy and imaging analysis is conducted as a comparative metric for scatterometry. In addition, optical model-based simulations are used to investigate MM elements' sensitivity to various DSA-based contact hole structures, predict sensitivity to dimensional changes, and its limits to characterize DSA-induced defects, such as hole placement inaccuracy, missing vias, and profile inaccuracy of the PMMA cylinder.

Effect of monochromatic aberrations on photorefractive patterns

NASA Astrophysics Data System (ADS)

Campbell, Melanie C. W.; Bobier, W. R.; Roorda, A.

1995-08-01

Photorefractive methods have become popular in the measurement of refractive and accommodative states of infants and children owing to their photographic nature and rapid speed of measurement. As in the case of any method that measures the refractive state of the human eye, monochromatic aberrations will reduce the accuracy of the measurement. Monochromatic aberrations cannot be as easily predicted or controlled as chromatic aberrations during the measurement, and accordingly they will introduce measurement errors. This study defines this error or uncertainty by extending the existing paraxial optical analyses of coaxial and eccentric photorefraction. This new optical analysis predicts that, for the amounts of spherical aberration (SA) reported for the human eye, there will be a significant degree of measurement uncertainty introduced for all photorefractive methods. The dioptric amount of this uncertainty may exceed the maximum amount of SA present in the eye. The calculated effects on photorefractive measurement of a real eye with a mixture of spherical aberration and coma are shown to be significant. The ability, developed here, to predict photorefractive patterns corresponding to different amounts and types of monochromatic aberration may in the future lead to an extension of photorefractive methods to the dual measurement of refractive states and aberrations of individual eyes. aberration, retinal image quality,

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

Kewley, Lisa J.; Dopita, Michael A.; Sutherland, Ralph

We use the chemical evolution predictions of cosmological hydrodynamic simulations with our latest theoretical stellar population synthesis, photoionization, and shock models to predict the strong line evolution of ensembles of galaxies from z = 3 to the present day. In this paper, we focus on the brightest optical emission-line ratios, [N II]/H{alpha} and [O III]/H{beta}. We use the optical diagnostic Baldwin-Phillips-Terlevich (BPT) diagram as a tool for investigating the spectral properties of ensembles of active galaxies. We use four redshift windows chosen to exploit new near-infrared multi-object spectrographs. We predict how the BPT diagram will appear in these four redshiftmore » windows given different sets of assumptions. We show that the position of star-forming galaxies on the BPT diagram traces the interstellar medium conditions and radiation field in galaxies at a given redshift. Galaxies containing active galactic nucleus (AGN) form a mixing sequence with purely star-forming galaxies. This mixing sequence may change dramatically with cosmic time, due to the metallicity sensitivity of the optical emission-lines. Furthermore, the position of the mixing sequence may probe metallicity gradients in galaxies as a function of redshift, depending on the size of the AGN narrow-line region. We apply our latest slow shock models for gas shocked by galactic-scale winds. We show that at high redshift, galactic wind shocks are clearly separated from AGN in line ratio space. Instead, shocks from galactic winds mimic high metallicity starburst galaxies. We discuss our models in the context of future large near-infrared spectroscopic surveys.« less

Inside supernova 1987A

NASA Technical Reports Server (NTRS)

Mccray, Richard; Shull, J. Michael; Sutherland, Peter

1987-01-01

The future evolution of the electromagnetic spectrum of the supernova 1987A is considered. It is shown that conventional models for supernova explosions predict that within several months a spectacular display of X-rays and UV emission lines will be seen from SN 1987A as the envelope expands to reveal the inner debris of the explosion. Two likely scenarios are considered: first, that the debris produces strong gamma rays from radioactive Co-56, and second, that an X-ray-emitting pulsar exists at the center. It is also predicted that a bright infrared echo will soon appear as a result of reprocessing of the optical/ultraviolet light by circumstellar grains; the luminosity of this echo can provide a sensitive test of the mass-loss history of the supernova progenitor.

Hardware development for Gravity Probe-B

NASA Technical Reports Server (NTRS)

Bardas, D.; Cheung, W. S.; Gill, D.; Hacker, R.; Keiser, G. M.

1986-01-01

Gravity Probe-B (GP-B), also known as the Stanford Relativity Gyroscope Experiment, will test two fundamental predictions of Einstein's General Theory of Relativity by precise measurement of the precessions of nearly perfect gyroscopes in earth orbit. This endeavor embodies state-of-the-art technologies in many fields, including gyroscope fabrication and readout, cryogenics, superconductivity, magnetic shielding, precision optics and alignment methods, and satellite control systems. These technologies are necessary to enable measurement of the predicted precession rates to the milliarcsecond/year level, and to reduce to 'near zero' all non-General Relativistic torques on the gyroscopes. This paper provides a brief overview of the experiment followed by descriptions of several specific hardware items with highlights on progress to date and plans for future development and tests.

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

Perspective and potential of smart optical materials

NASA Astrophysics Data System (ADS)

Choi, Sang H.; Duzik, Adam J.; Kim, Hyun-Jung; Park, Yeonjoon; Kim, Jaehwan; Ko, Hyun-U.; Kim, Hyun-Chan; Yun, Sungryul; Kyung, Ki-Uk

2017-09-01

The increasing requirements of hyperspectral imaging optics, electro/photo-chromic materials, negative refractive index metamaterial optics, and miniaturized optical components from micro-scale to quantum-scale optics have all contributed to new features and advancements in optics technology. Development of multifunctional capable optics has pushed the boundaries of optics into new fields that require new disciplines and materials to maximize the potential benefits. The purpose of this study is to understand and show the fundamental materials and fabrication technology for field-controlled spectrally active optics (referred to as smart optics) that are essential for future industrial, scientific, military, and space applications, such as membrane optics, filters, windows for sensors and probes, telescopes, spectroscopes, cameras, light valves, light switches, and flat-panel displays. The proposed smart optics are based on the Stark and Zeeman effects in materials tailored with quantum dot arrays and thin films made from readily polarizable materials via ferroelectricity or ferromagnetism. Bound excitonic states of organic crystals are also capable of optical adaptability, tunability, and reconfigurability. To show the benefits of smart optics, this paper reviews spectral characteristics of smart optical materials and device technology. Experiments testing the quantum-confined Stark effect, arising from rare earth element doping effects in semiconductors, and applied electric field effects on spectral and refractive index are discussed. Other bulk and dopant materials were also discovered to have the same aspect of shifts in spectrum and refractive index. Other efforts focus on materials for creating field-controlled spectrally smart active optics on a selected spectral range. Surface plasmon polariton transmission of light through apertures is also discussed, along with potential applications. New breakthroughs in micro scale multiple zone plate optics as a micro convex lens are reviewed, along with the newly discovered pseudo-focal point not predicted with conventional optics modeling. Micron-sized solid state beam scanner chips for laser waveguides are reviewed as well.

Combined fluorescence and reflectance spectroscopy for in vivo quantification of cancer biomarkers in low- and high-grade glioma surgery

PubMed Central

Valdés, Pablo A.; Kim, Anthony; Leblond, Frederic; Conde, Olga M.; Harris, Brent T.; Paulsen, Keith D.; Wilson, Brian C.; Roberts, David W.

2011-01-01

Biomarkers are indicators of biological processes and hold promise for the diagnosis and treatment of disease. Gliomas represent a heterogeneous group of brain tumors with marked intra- and inter-tumor variability. The extent of surgical resection is a significant factor influencing post-surgical recurrence and prognosis. Here, we used fluorescence and reflectance spectral signatures for in vivo quantification of multiple biomarkers during glioma surgery, with fluorescence contrast provided by exogenously-induced protoporphyrin IX (PpIX) following administration of 5-aminolevulinic acid. We performed light-transport modeling to quantify multiple biomarkers indicative of tumor biological processes, including the local concentration of PpIX and associated photoproducts, total hemoglobin concentration, oxygen saturation, and optical scattering parameters. We developed a diagnostic algorithm for intra-operative tissue delineation that accounts for the combined tumor-specific predictive capabilities of these quantitative biomarkers. Tumor tissue delineation achieved accuracies of up to 94% (specificity = 94%, sensitivity = 94%) across a range of glioma histologies beyond current state-of-the-art optical approaches, including state-of-the-art fluorescence image guidance. This multiple biomarker strategy opens the door to optical methods for surgical guidance that use quantification of well-established neoplastic processes. Future work would seek to validate the predictive power of this proof-of-concept study in a separate larger cohort of patients. PMID:22112112

Combined fluorescence and reflectance spectroscopy for in vivo quantification of cancer biomarkers in low- and high-grade glioma surgery

NASA Astrophysics Data System (ADS)

Valdés, Pablo A.; Kim, Anthony; Leblond, Frederic; Conde, Olga M.; Harris, Brent T.; Paulsen, Keith D.; Wilson, Brian C.; Roberts, David W.

2011-11-01

Biomarkers are indicators of biological processes and hold promise for the diagnosis and treatment of disease. Gliomas represent a heterogeneous group of brain tumors with marked intra- and inter-tumor variability. The extent of surgical resection is a significant factor influencing post-surgical recurrence and prognosis. Here, we used fluorescence and reflectance spectral signatures for in vivo quantification of multiple biomarkers during glioma surgery, with fluorescence contrast provided by exogenously-induced protoporphyrin IX (PpIX) following administration of 5-aminolevulinic acid. We performed light-transport modeling to quantify multiple biomarkers indicative of tumor biological processes, including the local concentration of PpIX and associated photoproducts, total hemoglobin concentration, oxygen saturation, and optical scattering parameters. We developed a diagnostic algorithm for intra-operative tissue delineation that accounts for the combined tumor-specific predictive capabilities of these quantitative biomarkers. Tumor tissue delineation achieved accuracies of up to 94% (specificity = 94%, sensitivity = 94%) across a range of glioma histologies beyond current state-of-the-art optical approaches, including state-of-the-art fluorescence image guidance. This multiple biomarker strategy opens the door to optical methods for surgical guidance that use quantification of well-established neoplastic processes. Future work would seek to validate the predictive power of this proof-of-concept study in a separate larger cohort of patients.

Failure prediction using machine learning and time series in optical network.

PubMed

Wang, Zhilong; Zhang, Min; Wang, Danshi; Song, Chuang; Liu, Min; Li, Jin; Lou, Liqi; Liu, Zhuo

2017-08-07

In this paper, we propose a performance monitoring and failure prediction method in optical networks based on machine learning. The primary algorithms of this method are the support vector machine (SVM) and double exponential smoothing (DES). With a focus on risk-aware models in optical networks, the proposed protection plan primarily investigates how to predict the risk of an equipment failure. To the best of our knowledge, this important problem has not yet been fully considered. Experimental results showed that the average prediction accuracy of our method was 95% when predicting the optical equipment failure state. This finding means that our method can forecast an equipment failure risk with high accuracy. Therefore, our proposed DES-SVM method can effectively improve traditional risk-aware models to protect services from possible failures and enhance the optical network stability.

CD-ROM-aided Databases

NASA Astrophysics Data System (ADS)

Masuyama, Keiichi

CD-ROM has rapidly evolved as a new information medium with large capacity, In the U.S. it is predicted that it will become two hundred billion yen market in three years, and thus CD-ROM is strategic target of database industry. Here in Japan the movement toward its commercialization has been active since this year. Shall CD-ROM bussiness ever conquer information market as an on-disk database or electronic publication? Referring to some cases of the applications in the U.S. the author views marketability and the future trend of this new optical disk medium.

OPTIC NERVE INFILTRATION BY RETINOBLASTOMA: Predictive Clinical Features and Outcome.

PubMed

Kaliki, Swathi; Tahiliani, Prerana; Mishra, Dilip K; Srinivasan, Visweswaran; Ali, Mohammed Hasnat; Reddy, Vijay Anand P

2016-06-01

To identify the clinical features predictive of any optic nerve infiltration and postlaminar optic nerve infiltration by retinoblastoma on histopathology and to report the outcome (metastasis and death) in these patients. Retrospective study. Of the 403 patients who underwent primary enucleation for retinoblastoma, 196 patients had optic nerve tumor infiltration (Group 1) and 207 patients had no evidence of optic nerve tumor infiltration (Group 2). Group 1 included patients with prelaminar (n = 47; 24%), laminar (n = 74; 38%), and postlaminar tumor infiltration with or without involving optic nerve transection (n = 74; 38%). Comparing Group 1 and Group 2, the patients in Group 1 had prolonged duration of symptoms (>6 months) (16% vs. 8%; P = 0.02) and were associated with no vision at presentation (23% vs. 10%; P = 0.01), higher rates of secondary glaucoma (42% vs. 12%; P < 0.0001), iris neovascularization (39% vs. 23%; P < 0.001), and larger tumors (mean tumor thickness, 12.8 mm vs. 12 mm; P = 0.0001). There was a higher prevalence of metastasis in Group 1 than in Group 2 (4% vs. 0%; P = 0.006). On multivariate analysis, clinical features predictive of any optic nerve tumor infiltration secondary glaucoma (hazard ratio = 5.38; P < 0.001) and those predictive of postlaminar optic nerve tumor infiltration included iris neovascularization (hazard ratio = 2.66; P = 0.001) and secondary glaucoma (hazard ratio = 3.13; P < 0.001). In this study, clinical features predictive of any optic nerve tumor infiltration included secondary glaucoma and those predictive of postlaminar optic nerve tumor infiltration included iris neovascularization and secondary glaucoma. Despite adjuvant treatment in those with postlaminar optic nerve tumor infiltration, metastasis occurred in 8% of patients.

Meta-shell Approach for Constructing Lightweight and High Resolution X-Ray Optics

NASA Technical Reports Server (NTRS)

McClelland, Ryan S.

2016-01-01

Lightweight and high resolution optics are needed for future space-based x-ray telescopes to achieve advances in high-energy astrophysics. Past missions such as Chandra and XMM-Newton have achieved excellent angular resolution using a full shell mirror approach. Other missions such as Suzaku and NuSTAR have achieved lightweight mirrors using a segmented approach. This paper describes a new approach, called meta-shells, which combines the fabrication advantages of segmented optics with the alignment advantages of full shell optics. Meta-shells are built by layering overlapping mirror segments onto a central structural shell. The resulting optic has the stiffness and rotational symmetry of a full shell, but with an order of magnitude greater collecting area. Several meta-shells so constructed can be integrated into a large x-ray mirror assembly by proven methods used for Chandra and XMM-Newton. The mirror segments are mounted to the meta-shell using a novel four point semi-kinematic mount. The four point mount deterministically locates the segment in its most performance sensitive degrees of freedom. Extensive analysis has been performed to demonstrate the feasibility of the four point mount and meta-shell approach. A mathematical model of a meta-shell constructed with mirror segments bonded at four points and subject to launch loads has been developed to determine the optimal design parameters, namely bond size, mirror segment span, and number of layers per meta-shell. The parameters of an example 1.3 m diameter mirror assembly are given including the predicted effective area. To verify the mathematical model and support opto-mechanical analysis, a detailed finite element model of a meta-shell was created. Finite element analysis predicts low gravity distortion and low thermal distortion. Recent results are discussed including Structural Thermal Optical Performance (STOP) analysis as well as vibration and shock testing of prototype meta-shells.

Optical droplet vaporization of nanoparticle-loaded stimuli-responsive microbubbles

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

Si, Ting; Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio 43210; Li, Guangbin

2016-03-14

A capillary co-flow focusing process is developed to generate stimuli-responsive microbubbles (SRMs) that comprise perfluorocarbon (PFC) suspension of silver nanoparticles (SNPs) in a lipid shell. Upon continuous laser irradiation at around their surface plasmon resonance band, the SNPs effectively absorb electromagnetic energy, induce heat accumulation in SRMs, trigger PFC vaporization, and eventually lead to thermal expansion and fragmentation of the SRMs. This optical droplet vaporization (ODV) process is further simulated by a theoretical model that combines heat generation of SNPs, phase change of PFC, and thermal expansion of SRMs. The model is validated by benchtop experiments, where the ODV processmore » is monitored by microscopic imaging. The effects of primary process parameters on behaviors of ODV are predicted by the theoretical model, indicating the technical feasibility for process control and optimization in future drug delivery applications.« less

Radar Astrometry of Asteroid 99942 (2004 MN4): Predicting the 2029 Earth Encounter and Beyond

NASA Astrophysics Data System (ADS)

Giorgini, J. D.; Benner, L. A. M.; Nolan, M. C.; Ostro, S. J.

2005-08-01

Asteroid 2004 MN4 is expected to pass 4.6 (+/- 1.6) Earth-radii above the surface of the Earth on 2029-Apr-13. Such close approaches by objects as large as 2004 MN4 (D ≳ 0.3 km) are thought to occur at ≳ 1000-year intervals on average. 2004 MN4 is expected to reach 3rd magnitude and thus be visible to the unaided eye. With a disk 2-4 arcseconds across, it may be resolved by ground-based telescopes. Arecibo (2380-MHz) delay-Doppler radar astrometry, obtained in late January 2005, significantly corrected 2004 MN4's orbit by revealing a 1.4 arcsecond bias in pre-discovery optical measurements. Doppler-shifted echoes were acquired 4.8σ (176.4 mm/s) away from the predicted frequency on Jan 27. Range on Jan 29 was found to be 747 km (2.8σ ) closer to Earth than the pre-radar orbit predicted. Incorporation of these delay-Doppler measurements into a new weighted least-squares orbit solution moved the 2029-Apr-13 encounter prediction 5σ closer to the Earth, illustrating the problematic nature of prediction and statistical analysis with single-apparition optical data-sets. Without delay-Doppler data, the bias was not apparent, even when optical measurements spanned a full orbit period. The current combined data-set does not permit reliable trajectory propagation to encounters beyond 2029; Monte Carlo analysis shows that, by 2036, the 3σ confidence region wraps >300 degrees of heliocentric longitude around the Sun, with some sections of this statistical region experiencing low-probability encounters with the Earth in the 2030's, gravitationally scattering some possible trajectories inward to the orbit of Venus, or outward toward Mars. Future measurements from radar opportunities in August 2005 and May 2006 (SNR ≈5-10) have the potential to eliminate statistical encounters in the 2030's. Delay-Doppler astrometry from 2013 (SNR ≈30) should permit deterministic encounter prediction through 2070, shrinking the along-track uncertainty in 2036 by two orders of magnitude,from ≳ 8(10)8 km to ≲7(10)6 km.

Experimental Validation of Displacement Underestimation in ARFI Ultrasound

PubMed Central

Czernuszewicz, Tomasz J.; Streeter, Jason E.; Dayton, Paul A.; Gallippi, Caterina M.

2014-01-01

Acoustic radiation force impulse (ARFI) imaging is an elastography technique that uses ultrasonic pulses to both displace and track tissue motion. Previous modeling studies have shown that ARFI displacements are susceptible to underestimation due to lateral and elevational shearing that occurs within the tracking resolution cell. In this study, optical tracking was utilized to experimentally measure the displacement underestimation achieved by acoustic tracking using a clinical ultrasound system. Three optically translucent phantoms of varying stiffness were created, embedded with sub-wavelength diameter microspheres, and ARFI excitation pulses with F/1.5 or F/3 lateral focal configurations were transmitted from a standard linear array to induce phantom motion. Displacements were tracked using confocal optical and acoustic methods. As predicted by earlier FEM studies, significant acoustic displacement underestimation was observed for both excitation focal configurations; the maximum underestimation error was 35% of the optically measured displacement for the F/1.5 excitation pulse in the softest phantom. Using higher F/#, less tightly focused beams in the lateral dimension improved accuracy of displacements by approximately 10 percentage points. This work experimentally demonstrates limitations of ARFI implemented on a clinical scanner using a standard linear array and sets up a framework for future displacement tracking validation studies. PMID:23858054

Molecular effective coverage surface area of optical clearing agents for predicting optical clearing potential

NASA Astrophysics Data System (ADS)

Feng, Wei; Ma, Ning; Zhu, Dan

2015-03-01

The improvement of methods for optical clearing agent prediction exerts an important impact on tissue optical clearing technique. The molecular dynamic simulation is one of the most convincing and simplest approaches to predict the optical clearing potential of agents by analyzing the hydrogen bonds, hydrogen bridges and hydrogen bridges type forming between agents and collagen. However, the above analysis methods still suffer from some problem such as analysis of cyclic molecule by reason of molecular conformation. In this study, a molecular effective coverage surface area based on the molecular dynamic simulation was proposed to predict the potential of optical clearing agents. Several typical cyclic molecules, fructose, glucose and chain molecules, sorbitol, xylitol were analyzed by calculating their molecular effective coverage surface area, hydrogen bonds, hydrogen bridges and hydrogen bridges type, respectively. In order to verify this analysis methods, in vitro skin samples optical clearing efficacy were measured after 25 min immersing in the solutions, fructose, glucose, sorbitol and xylitol at concentration of 3.5 M using 1951 USAF resolution test target. The experimental results show accordance with prediction of molecular effective coverage surface area. Further to compare molecular effective coverage surface area with other parameters, it can show that molecular effective coverage surface area has a better performance in predicting OCP of agents.

Communications Via Undersea Cables: Present And Future

NASA Astrophysics Data System (ADS)

Paul, D. K.

1985-11-01

Advances in fiber optic technology in the past few years have firmly established the superiority of optical fiber to coaxial cables, particularly for large-capacity, long-haul transmission systems. Recently, several undersea fiber optic cable systems have been proposed by both common and noncommon carriers. This paper addresses the techno-economic implications of these applications, and includes a brief review of the current status of undersea cable technology and a projection of future demand and capabilities. The prospects for using high-speed, multifiber undersea cable systems for international communications, extension of these systems through fiber optic terrestrial distribution, and future developmental trends are critically assessed.

Control, Filtering and Prediction for Phased Arrays in Directed Energy Systems

DTIC Science & Technology

2016-04-30

adaptive optics. 15. SUBJECT TERMS control, filtering, prediction, system identification, adaptive optics, laser beam pointing, target tracking, phase... laser beam control; furthermore, wavefront sensors are plagued by the difficulty of maintaining the required alignment and focusing in dynamic mission...developed new methods for filtering, prediction and system identification in adaptive optics for high energy laser systems including phased arrays. The

Prediction of daily fine particulate matter concentrations using aerosol optical depth retrievals from the Geostationary Operational Environmental Satellite (GOES).

PubMed

Chudnovsky, Alexandra A; Lee, Hyung Joo; Kostinski, Alex; Kotlov, Tanya; Koutrakis, Petros

2012-09-01

Although ground-level PM2.5 (particulate matter with aerodynamic diameter < 2.5 microm) monitoring sites provide accurate measurements, their spatial coverage within a given region is limited and thus often insufficient for exposure and epidemiological studies. Satellite data expand spatial coverage, enhancing our ability to estimate location- and/or subject-specific exposures to PM2.5. In this study, the authors apply a mixed-effects model approach to aerosol optical depth (AOD) retrievals from the Geostationary Operational Environmental Satellite (GOES) to predict PM2.5 concentrations within the New England area of the United States. With this approach, it is possible to control for the inherent day-to-day variability in the AOD-PM2.5 relationship, which depends on time-varying parameters such as particle optical properties, vertical and diurnal concentration profiles, and ground surface reflectance. The model-predicted PM2.5 mass concentration are highly correlated with the actual observations, R2 = 0.92. Therefore, adjustment for the daily variability in AOD-PM2.5 relationship allows obtaining spatially resolved PM2.5 concentration data that can be of great value to future exposure assessment and epidemiological studies. The authors demonstrated how AOD can be used reliably to predict daily PM2.5 mass concentrations, providing determination of their spatial and temporal variability. Promising results are found by adjusting for daily variability in the AOD-PM2.5 relationship, without the need to account for a wide variety of individual additional parameters. This approach is of a great potential to investigate the associations between subject-specific exposures to PM2.5 and their health effects. Higher 4 x 4-km resolution GOES AOD retrievals comparing with the conventional MODerate resolution Imaging Spectroradiometer (MODIS) 10-km product has the potential to capture PM2.5 variability within the urban domain.

Quantitative contrast-enhanced optical coherence tomography

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

Winetraub, Yonatan; SoRelle, Elliott D.; Bio-X Program, Stanford University, 299 Campus Drive, Stanford, California 94305

2016-01-11

We have developed a model to accurately quantify the signals produced by exogenous scattering agents used for contrast-enhanced Optical Coherence Tomography (OCT). This model predicts distinct concentration-dependent signal trends that arise from the underlying physics of OCT detection. Accordingly, we show that real scattering particles can be described as simplified ideal scatterers with modified scattering intensity and concentration. The relation between OCT signal and particle concentration is approximately linear at concentrations lower than 0.8 particle per imaging voxel. However, at higher concentrations, interference effects cause signal to increase with a square root dependence on the number of particles within amore » voxel. Finally, high particle concentrations cause enough light attenuation to saturate the detected signal. Predictions were validated by comparison with measured OCT signals from gold nanorods (GNRs) prepared in water at concentrations ranging over five orders of magnitude (50 fM to 5 nM). In addition, we validated that our model accurately predicts the signal responses of GNRs in highly heterogeneous scattering environments including whole blood and living animals. By enabling particle quantification, this work provides a valuable tool for current and future contrast-enhanced in vivo OCT studies. More generally, the model described herein may inform the interpretation of detected signals in modalities that rely on coherence-based detection or are susceptible to interference effects.« less

ZY3-02 Laser Altimeter Footprint Geolocation Prediction

PubMed Central

Xie, Junfeng; Tang, Xinming; Mo, Fan; Li, Guoyuan; Zhu, Guangbin; Wang, Zhenming; Fu, Xingke; Gao, Xiaoming; Dou, Xianhui

2017-01-01

Successfully launched on 30 May 2016, ZY3-02 is the first Chinese surveying and mapping satellite equipped with a lightweight laser altimeter. Calibration is necessary before the laser altimeter becomes operational. Laser footprint location prediction is the first step in calibration that is based on ground infrared detectors, and it is difficult because the sample frequency of the ZY3-02 laser altimeter is 2 Hz, and the distance between two adjacent laser footprints is about 3.5 km. In this paper, we build an on-orbit rigorous geometric prediction model referenced to the rigorous geometric model of optical remote sensing satellites. The model includes three kinds of data that must be predicted: pointing angle, orbit parameters, and attitude angles. The proposed method is verified by a ZY3-02 laser altimeter on-orbit geometric calibration test. Five laser footprint prediction experiments are conducted based on the model, and the laser footprint prediction accuracy is better than 150 m on the ground. The effectiveness and accuracy of the on-orbit rigorous geometric prediction model are confirmed by the test results. The geolocation is predicted precisely by the proposed method, and this will give a reference to the geolocation prediction of future land laser detectors in other laser altimeter calibration test. PMID:28934160

ZY3-02 Laser Altimeter Footprint Geolocation Prediction.

PubMed

Xie, Junfeng; Tang, Xinming; Mo, Fan; Li, Guoyuan; Zhu, Guangbin; Wang, Zhenming; Fu, Xingke; Gao, Xiaoming; Dou, Xianhui

2017-09-21

Successfully launched on 30 May 2016, ZY3-02 is the first Chinese surveying and mapping satellite equipped with a lightweight laser altimeter. Calibration is necessary before the laser altimeter becomes operational. Laser footprint location prediction is the first step in calibration that is based on ground infrared detectors, and it is difficult because the sample frequency of the ZY3-02 laser altimeter is 2 Hz, and the distance between two adjacent laser footprints is about 3.5 km. In this paper, we build an on-orbit rigorous geometric prediction model referenced to the rigorous geometric model of optical remote sensing satellites. The model includes three kinds of data that must be predicted: pointing angle, orbit parameters, and attitude angles. The proposed method is verified by a ZY3-02 laser altimeter on-orbit geometric calibration test. Five laser footprint prediction experiments are conducted based on the model, and the laser footprint prediction accuracy is better than 150 m on the ground. The effectiveness and accuracy of the on-orbit rigorous geometric prediction model are confirmed by the test results. The geolocation is predicted precisely by the proposed method, and this will give a reference to the geolocation prediction of future land laser detectors in other laser altimeter calibration test.

Improved Dynamic Lightpath Provisioning for Large Wavelength-Division Multiplexed Backbones

NASA Astrophysics Data System (ADS)

Kong, Huifang; Phillips, Chris

2007-07-01

Technology already exists that would allow future optical networks to support automatic lightpath configuration in response to dynamic traffic demands. Given appropriate commercial drivers, it is possible to foresee carrier network operators migrating away from semipermanent provisioning to enable on-demand short-duration communications. However, with traditional lightpath reservation protocols, a portion of the lightpath is idly held during the signaling propagation phase, which can significantly reduce the lightpath bandwidth efficiency in large wavelength-division multiplexed backbones. This paper proposes a prebooking mechanism to improve the lightpath efficiency over traditional reactive two-way reservation protocols, consequently liberating network resources to support higher traffic loads. The prebooking mechanism predicts the time when the traffic will appear at the optical cross connects, and intelligently schedules the lightpath components such that resources are only consumed as necessary. We describe the proposed signaling procedure for both centralized and distributed control planes and analyze its performance. This paper also investigates the aggregated flow length characteristics with the self-similar incident traffic and examines the effects of traffic prediction on the blocking probability as well as the ability to support latency sensitive traffic in a wide-area environment.

Diffusion-Weighted Imaging of Traumatic Optic Neuropathy: Diagnosis and Predicting the Prognosis

DTIC Science & Technology

2014-01-01

AFRL-SA-WP-SR-2014-0004 Diffusion-Weighted Imaging of Traumatic Optic Neuropathy : Diagnosis and Predicting the Prognosis...Diffusion-Weighted Imaging of Traumatic Optic Neuropathy : Diagnosis and Predicting the Prognosis 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c...Skills Institute C-STARS Baltimore 2510 Fifth St. Wright-Patterson AFB, OH 45433-7913 8 . PERFORMING ORGANIZATION REPORT NUMBER AFRL-SA

Relationship of college student characteristics and inquiry-based geometrical optics instruction to knowledge of image formation with light-ray tracing

NASA Astrophysics Data System (ADS)

Isik, Hakan

This study is premised on the fact that student conceptions of optics appear to be unrelated to student characteristics of gender, age, years since high school graduation, or previous academic experiences. This study investigated the relationships between student characteristics and student performance on image formation test items and the changes in student conceptions of optics after an introductory inquiry-based physics course. Data was collected from 39 college students who were involved in an inquiry-based physics course teaching topics of geometrical optics. Student data concerning characteristics and previous experiences with optics and mathematics were collected. Assessment of student understanding of optics knowledge for pinholes, plane mirrors, refraction, and convex lenses was collected with, the Test of Image Formation with Light-Ray Tracing instrument. Total scale and subscale scores representing the optics instrument content were derived from student pretest and posttest responses. The types of knowledge, needed to answer each optics item correctly, were categorized as situational, conceptual, procedural, and strategic knowledge. These types of knowledge were associated with student correct and incorrect responses to each item to explain the existences and changes in student scientific and naive conceptions. Correlation and stepwise multiple regression analyses were conducted to identify the student characteristics and academic experiences that significantly predicted scores on the subscales of the test. The results showed that student experience with calculus was a significant predictor of student performance on the total scale as well as on the refraction subscale of the Test of Image Formation with Light-Ray Tracing. A combination of student age and previous academic experience with precalculus was a significant predictor of student performance on the pretest pinhole subscale. Student characteristic of years since high school graduation significantly predicted the gain in student scores on pinhole and plane-mirror items from the pretest to the posttest with those students who were most recent graduates from high school doing better. Multivariate and univariate analyses of variance of the Test of Image Formation with Light-Ray Tracing pinhole scale and individual item changes from the pretest to the posttest resulted in statistically significant mean differences between total scores as well as between various individual pinhole items. There were no significant changes for individual plane-mirror items from pretest to posttest. Results revealed that there is a perceivable relationship between student optics-content knowledge and the types of knowledge required by items. At the pretest, the greatest selection of wrong responses related to the items requiring situational type of knowledge and the fewest selection of wrong responses was relate to the items requiring procedural type of knowledge. Student selection of wrong options for each item revealed the following naive optics conceptions: pinholes do not create reversed images (pretest), size and sharpness of pinhole images are related to the focus of a pinhole camera (pretest and posttest); propagation of light rays are interpreted as being radial rather than directional (pretest and posttest); no conception of image formation and observation for parallel mirrors (pretest and posttest), the place of an image depends on the position of the observer (pretest and posttest), a plane mirror reflects the images of the objects placed at one side of the mirror and the observers who were positioned at the other side of the mirror can see them (pretest and posttest); applying the law of reflection to plane mirrors without considering the variations in angles of incidence and reflection (pretest and posttest), and image observation is confused with the image formation in mirrors placed perpendicular to one another (pretest and posttest). Future research should focus on the acquisition, development, and identification of reliable measures of optics concepts, processes, types of knowledge, and specific optics understanding (i.e., pinhole, plane-mirror). Future research should focus on the identification of the more critical concepts such as changes in size and sharpness of pinhole images, image observation, image formation in general, and image formation and observation in parallel mirrors. Future research can be conducted with a larger set of participants so as to compare different instructional methods and address instructional deficiencies using more efficient statistical methods. Comparative studies can be conducted to investigate the relations of various instructional strategies on student conceptions of optics.

Nanomanipulation of Single RNA Molecules by Optical Tweezers

PubMed Central

Stephenson, William; Wan, Gorby; Tenenbaum, Scott A.; Li, Pan T. X.

2014-01-01

A large portion of the human genome is transcribed but not translated. In this post genomic era, regulatory functions of RNA have been shown to be increasingly important. As RNA function often depends on its ability to adopt alternative structures, it is difficult to predict RNA three-dimensional structures directly from sequence. Single-molecule approaches show potentials to solve the problem of RNA structural polymorphism by monitoring molecular structures one molecule at a time. This work presents a method to precisely manipulate the folding and structure of single RNA molecules using optical tweezers. First, methods to synthesize molecules suitable for single-molecule mechanical work are described. Next, various calibration procedures to ensure the proper operations of the optical tweezers are discussed. Next, various experiments are explained. To demonstrate the utility of the technique, results of mechanically unfolding RNA hairpins and a single RNA kissing complex are used as evidence. In these examples, the nanomanipulation technique was used to study folding of each structural domain, including secondary and tertiary, independently. Lastly, the limitations and future applications of the method are discussed. PMID:25177917

Electron optics with ballistic graphene junctions

NASA Astrophysics Data System (ADS)

Chen, Shaowen

Electrons transmitted across a ballistic semiconductor junction undergo refraction, analogous to light rays across an optical boundary. A pn junction theoretically provides the equivalent of a negative index medium, enabling novel electron optics such as negative refraction and perfect (Veselago) lensing. In graphene, the linear dispersion and zero-gap bandstructure admit highly transparent pn junctions by simple electrostatic gating, which cannot be achieved in conventional semiconductors. Robust demonstration of these effects, however, has not been forthcoming. Here we employ transverse magnetic focusing to probe propagation across an electrostatically defined graphene junction. We find perfect agreement with the predicted Snell's law for electrons, including observation of both positive and negative refraction. Resonant transmission across the pn junction provides a direct measurement of the angle dependent transmission coefficient, and we demonstrate good agreement with theory. Comparing experimental data with simulation reveals the crucial role played by the effective junction width, providing guidance for future device design. Efforts toward sharper pn junction and possibility of zero field Veselago lensing will also be discussed. This work is supported by the Semiconductor Research Corporations NRI Center for Institute for Nanoelectronics Discovery and Exploration (INDEX).

Improving the fiber coupling efficiency for DARWIN by loss-less shaping of the receive beams

NASA Astrophysics Data System (ADS)

Voland, Ch.; Weigel, Th.; Dreischer, Th.; Wallner, O.; Ergenzinger, K.; Ries, H.; Jetter, R.; Vosteen, A.

2017-11-01

For the DARWIN mission the extremely low planet signal levels require an optical instrument design with utmost efficiency to guarantee the required science performance. By shaping the transverse amplitude and phase distributions of the receive beams, the singlemode fibre coupling efficiency can be increased to almost 100%, thus allowing for a gain of more than 20% compared to conventional designs. We show that the use of "tailored freeform surfaces" for purpose of beam shaping dramatically reduces the coupling degradations, which otherwise result from mode mismatch between the Airy pattern of the image and the fibre mode, and therefore allows for achieving a performance close to the physical limitations. We present an application of tailored surfaces for building a beam shaping optics that shall enhance fibre coupling performance as core part of a space based interferometer in the future DARWIN mission and present performance predictions by wave-optical simulations. We assess the feasibility of manufacturing the corresponding tailored surfaces and describe the proof of concept demonstrator we use for experimental performance verification.

Controlling the dynamics of quantum mechanical systems sustaining dipole-forbidden transitions via optical nanoantennas

NASA Astrophysics Data System (ADS)

Filter, Robert; Mühlig, Stefan; Eichelkraut, Toni; Rockstuhl, Carsten; Lederer, Falk

2012-07-01

We suggest to excite dipole-forbidden transitions in quantum mechanical systems by using appropriately designed optical nanoantennas. The antennas are tailored such that their near field contains sufficiently strong contributions of higher-order multipole moments. The strengths of these moments exceed their free-space analogs by several orders of magnitude. The impact of such excitation enhancement is exemplarily investigated by studying the dynamics of a three-level system. It decays upon excitation by an electric quadrupole transition via two electric dipole transitions. Since one dipole transition is assumed to be radiative, the enhancement of this emission serves as a figure of merit. Such self-consistent treatment of excitation, emission, and internal dynamics as developed in this contribution is the key to predict any observable quantity. The suggested scheme may represent a blueprint for future experiments and will find many obvious spectroscopic and sensing applications.

Computational Screening of 2D Materials for Photocatalysis.

PubMed

Singh, Arunima K; Mathew, Kiran; Zhuang, Houlong L; Hennig, Richard G

2015-03-19

Two-dimensional (2D) materials exhibit a range of extraordinary electronic, optical, and mechanical properties different from their bulk counterparts with potential applications for 2D materials emerging in energy storage and conversion technologies. In this Perspective, we summarize the recent developments in the field of solar water splitting using 2D materials and review a computational screening approach to rapidly and efficiently discover more 2D materials that possess properties suitable for solar water splitting. Computational tools based on density-functional theory can predict the intrinsic properties of potential photocatalyst such as their electronic properties, optical absorbance, and solubility in aqueous solutions. Computational tools enable the exploration of possible routes to enhance the photocatalytic activity of 2D materials by use of mechanical strain, bias potential, doping, and pH. We discuss future research directions and needed method developments for the computational design and optimization of 2D materials for photocatalysis.

Radioluminescence and photoluminescence of Th:CaF2 crystals

PubMed Central

Stellmer, Simon; Schreitl, Matthias; Schumm, Thorsten

2015-01-01

We study thorium-doped CaF2 crystals as a possible platform for optical spectroscopy of the 229Th nuclear isomer transition. We anticipate two major sources of background signal that might cover the nuclear spectroscopy signal: VUV-photoluminescence, caused by the probe light, and radioluminescence, caused by the radioactive decay of 229Th and its daughters. We find a rich photoluminescence spectrum at wavelengths above 260 nm, and radioluminescence emission above 220 nm. This is very promising, as fluorescence originating from the isomer transition, predicted at a wavelength shorter than 200 nm, could be filtered spectrally from the crystal luminescence. Furthermore, we investigate the temperature-dependent decay time of the luminescence, as well as thermoluminescence properties. Our findings allow for an immediate optimization of spectroscopy protocols for both the initial search for the nuclear transition using synchrotron radiation, as well as future optical clock operation with narrow-linewidth lasers. PMID:26502749

Modelling the KIC8462852 light curves: compatibility of the dips and secular dimming with an exocomet interpretation

NASA Astrophysics Data System (ADS)

Wyatt, M. C.; van Lieshout, R.; Kennedy, G. M.; Boyajian, T. S.

2018-02-01

This paper shows how the dips and secular dimming in the KIC8462852 light curve can originate in circumstellar material distributed around a single elliptical orbit (e.g. exocomets). The expected thermal emission and wavelength dependent dimming is derived for different orbital parameters and geometries, including dust that is optically thick to stellar radiation, and for a size distribution of dust with realistic optical properties. We first consider dust distributed evenly around the orbit, then show how to derive its uneven distribution from the optical light curve and to predict light curves at different wavelengths. The fractional luminosity of an even distribution is approximately the level of dimming times stellar radius divided by distance from the star at transit. Non-detection of dust thermal emission for KIC8462852 thus provides a lower limit on the transit distance to complement the 0.6 au upper limit imposed by 0.4 d dips. Unless the dust distribution is optically thick, the putative 16 per cent century-long secular dimming must have disappeared before the WISE 12 μm measurement in 2010, and subsequent 4.5 μm observations require transits at >0.05 au. However, self-absorption of thermal emission removes these constraints for opaque dust distributions. The passage of dust clumps through pericentre is predicted to cause infrared brightening lasting tens of days and dimming during transit, such that total flux received decreases at wavelengths <5 μm, but increases to potentially detectable levels at longer wavelengths. We suggest that lower dimming levels than seen for KIC8462852 are more common in the Galactic population and may be detected in future transit surveys.

Lightweight deformable mirrors for future space telescopes

NASA Astrophysics Data System (ADS)

Patterson, Keith

This thesis presents a concept for ultra-lightweight deformable mirrors based on a thin substrate of optical surface quality coated with continuous active piezopolymer layers that provide modes of actuation and shape correction. This concept eliminates any kind of stiff backing structure for the mirror surface and exploits micro-fabrication technologies to provide a tight integration of the active materials into the mirror structure, to avoid actuator print-through effects. Proof-of-concept, 10-cm-diameter mirrors with a low areal density of about 0.5 kg/m2 have been designed, built and tested to measure their shape-correction performance and verify the models used for design. The low cost manufacturing scheme uses replication techniques, and strives for minimizing residual stresses that deviate the optical figure from the master mandrel. It does not require precision tolerancing, is lightweight, and is therefore potentially scalable to larger diameters for use in large, modular space telescopes. Other potential applications for such a laminate could include ground-based mirrors for solar energy collection, adaptive optics for atmospheric turbulence, laser communications, and other shape control applications. The immediate application for these mirrors is for the Autonomous Assembly and Reconfiguration of a Space Telescope (AAReST) mission, which is a university mission under development by Caltech, the University of Surrey, and JPL. The design concept, fabrication methodology, material behaviors and measurements, mirror modeling, mounting and control electronics design, shape control experiments, predictive performance analysis, and remaining challenges are presented herein. The experiments have validated numerical models of the mirror, and the mirror models have been used within a model of the telescope in order to predict the optical performance. A demonstration of this mirror concept, along with other new telescope technologies, is planned to take place during the AAReST mission.

Design and Analysis of an X-Ray Mirror Assembly Using the Meta-Shell Approach

NASA Technical Reports Server (NTRS)

McClelland, Ryan S.; Bonafede, Joseph; Saha, Timo T.; Solly, Peter M.; Zhang, William W.

2016-01-01

Lightweight and high resolution optics are needed for future space-based x-ray telescopes to achieve advances in high-energy astrophysics. Past missions such as Chandra and XMM-Newton have achieved excellent angular resolution using a full shell mirror approach. Other missions such as Suzaku and NuSTAR have achieved lightweight mirrors using a segmented approach. This paper describes a new approach, called meta-shells, which combines the fabrication advantages of segmented optics with the alignment advantages of full shell optics. Meta-shells are built by layering overlapping mirror segments onto a central structural shell. The resulting optic has the stiffness and rotational symmetry of a full shell, but with an order of magnitude greater collecting area. Several meta-shells so constructed can be integrated into a large x-ray mirror assembly by proven methods used for Chandra and XMM-Newton. The mirror segments are mounted to the meta-shell using a novel four point semi-kinematic mount. The four point mount deterministically locates the segment in its most performance sensitive degrees of freedom. Extensive analysis has been performed to demonstrate the feasibility of the four point mount and meta-shell approach. A mathematical model of a meta-shell constructed with mirror segments bonded at four points and subject to launch loads has been developed to determine the optimal design parameters, namely bond size, mirror segment span, and number of layers per meta-shell. The parameters of an example 1.3 m diameter mirror assembly are given including the predicted effective area. To verify the mathematical model and support opto-mechanical analysis, a detailed finite element model of a meta-shell was created. Finite element analysis predicts low gravity distortion and low sensitivity to thermal gradients.

Efficacy of predictive wavefront control for compensating aero-optical aberrations

NASA Astrophysics Data System (ADS)

Goorskey, David J.; Schmidt, Jason; Whiteley, Matthew R.

2013-07-01

Imaging and laser beam propagation from airborne platforms are degraded by dynamic aberrations due to air flow around the aircraft, aero-mechanical distortions and jitter, and free atmospheric turbulence. For certain applications, like dim-object imaging, free-space optical communications, and laser weapons, adaptive optics (AO) is necessary to compensate for the aberrations in real time. Aero-optical flow is a particularly interesting source of aberrations whose flowing structures can be exploited by adaptive and predictive AO controllers, thereby realizing significant performance gains. We analyze dynamic aero-optical wavefronts to determine the pointing angles at which predictive wavefront control is more effective than conventional, fixed-gain, linear-filter control. It was found that properties of the spatial decompositions and temporal statistics of the wavefronts are directly traceable to specific features in the air flow. Furthermore, the aero-optical wavefront aberrations at the side- and aft-looking angles were the most severe, but they also benefited the most from predictive AO.

Prediction of accommodative optical response in prepresbyopic patients using ultrasound biomicroscopy

PubMed Central

Ramasubramanian, Viswanathan; Glasser, Adrian

2015-01-01

PURPOSE To determine whether relatively low-resolution ultrasound biomicroscopy (UBM) can predict the accommodative optical response in prepresbyopic eyes as well as in a previous study of young phakic subjects, despite lower accommodative amplitudes. SETTING College of Optometry, University of Houston, Houston, USA. DESIGN Observational cross-sectional study. METHODS Static accommodative optical response was measured with infrared photorefraction and an autorefractor (WR-5100K) in subjects aged 36 to 46 years. A 35 MHz UBM device (Vumax, Sonomed Escalon) was used to image the left eye, while the right eye viewed accommodative stimuli. Custom-developed Matlab image-analysis software was used to perform automated analysis of UBM images to measure the ocular biometry parameters. The accommodative optical response was predicted from biometry parameters using linear regression, 95% confidence intervals (CIs), and 95% prediction intervals. RESULTS The study evaluated 25 subjects. Per-diopter (D) accommodative changes in anterior chamber depth (ACD), lens thickness, anterior and posterior lens radii of curvature, and anterior segment length were similar to previous values from young subjects. The standard deviations (SDs) of accommodative optical response predicted from linear regressions for UBM-measured biometry parameters were ACD, 0.15 D; lens thickness, 0.25 D; anterior lens radii of curvature, 0.09 D; posterior lens radii of curvature, 0.37 D; and anterior segment length, 0.42 D. CONCLUSIONS Ultrasound biomicroscopy parameters can, on average, predict accommodative optical response with SDs of less than 0.55 D using linear regressions and 95% CIs. Ultrasound biomicroscopy can be used to visualize and quantify accommodative biometric changes and predict accommodative optical response in prepresbyopic eyes. PMID:26049831

A Search for Kilonovae in the Dark Energy Survey

DOE PAGES

Doctor, Z.; Kessler, R.; Chen, H. Y.; ...

2017-03-01

The coalescence of a binary neutron star pair is expected to produce gravitational waves (GW) and electromagnetic radiation, both of which may be detectable with currently available instruments. In this paper, we describe a search for a predicted r-process optical transient from these mergers, dubbed the “kilonova” (KN), using griz broadband data from the Dark Energy Survey Supernova Program (DES-SN). Some models predict KNe to be redder, shorter-lived, and dimmer than supernovae (SNe), but the event rate of KNe is poorly constrained. We simulate KN and SN light curves with the Monte-Carlo simulation code SNANA to optimize selection requirements, determine search efficiency, and predict SN backgrounds. Our analysis of the first two seasons of DES-SN data results in 0 events, and is consistent with our prediction of 1.1 ± 0.2 background events based on simulations of SNe. From our prediction, there is a 33% chance of finding 0 events in the data. Assuming no underlying galaxy flux, our search sets 90% upper limits on the KN volumetric rate of 1.0 x 10more » $$^{7}$$ Gpc $-$3 yr $-$1 for the dimmest KN model we consider (peak i-band absolute magnitude $${M}_{i}=-11.4$$ mag) and 2.4x 10$$^{4}$$ Gpc $-$3 yr $-$1 for the brightest ($${M}_{i}=-16.2$$ mag). Accounting for anomalous subtraction artifacts on bright galaxies, these limits are ~3 times higher. This analysis is the first untriggered optical KN search and informs selection requirements and strategies for future KN searches. Finally, our upper limits on the KN rate are consistent with those measured by GW and gamma-ray burst searches.« less

A Search for Kilonovae in the Dark Energy Survey

NASA Astrophysics Data System (ADS)

Doctor, Z.; Kessler, R.; Chen, H. Y.; Farr, B.; Finley, D. A.; Foley, R. J.; Goldstein, D. A.; Holz, D. E.; Kim, A. G.; Morganson, E.; Sako, M.; Scolnic, D.; Smith, M.; Soares-Santos, M.; Spinka, H.; Abbott, T. M. C.; Abdalla, F. B.; Allam, S.; Annis, J.; Bechtol, K.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Burke, D. L.; Carnero Rosell, A.; Carrasco Kind, M.; Carretero, J.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; DePoy, D. L.; Desai, S.; Diehl, H. T.; Drlica-Wagner, A.; Eifler, T. F.; Frieman, J.; García-Bellido, J.; Gaztanaga, E.; Gerdes, D. W.; Gruendl, R. A.; Gschwend, J.; Gutierrez, G.; James, D. J.; Krause, E.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Li, T. S.; Lima, M.; Maia, M. A. G.; March, M.; Marshall, J. L.; Menanteau, F.; Miquel, R.; Neilsen, E.; Nichol, R. C.; Nord, B.; Plazas, A. A.; Romer, A. K.; Sanchez, E.; Scarpine, V.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, R. C.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Walker, A. R.; Wester, W.; DES Collaboration

2017-03-01

The coalescence of a binary neutron star pair is expected to produce gravitational waves (GW) and electromagnetic radiation, both of which may be detectable with currently available instruments. We describe a search for a predicted r-process optical transient from these mergers, dubbed the “kilonova” (KN), using griz broadband data from the Dark Energy Survey Supernova Program (DES-SN). Some models predict KNe to be redder, shorter-lived, and dimmer than supernovae (SNe), but the event rate of KNe is poorly constrained. We simulate KN and SN light curves with the Monte-Carlo simulation code SNANA to optimize selection requirements, determine search efficiency, and predict SN backgrounds. Our analysis of the first two seasons of DES-SN data results in 0 events, and is consistent with our prediction of 1.1 ± 0.2 background events based on simulations of SNe. From our prediction, there is a 33% chance of finding 0 events in the data. Assuming no underlying galaxy flux, our search sets 90% upper limits on the KN volumetric rate of 1.0 × {10}7 Gpc-3 yr-1 for the dimmest KN model we consider (peak I-band absolute magnitude {M}I=-11.4 mag) and 2.4 × {10}4 Gpc-3 yr-1 for the brightest ({M}I=-16.2 mag). Accounting for anomalous subtraction artifacts on bright galaxies, these limits are ˜3 times higher. This analysis is the first untriggered optical KN search and informs selection requirements and strategies for future KN searches. Our upper limits on the KN rate are consistent with those measured by GW and gamma-ray burst searches.

Remotely piloted aircraft in the civil environment

NASA Technical Reports Server (NTRS)

Gregory, T. J.; Nelms, W. P.; Karmarkar, J. S.

1977-01-01

Improved remotely piloted aircraft (RPAs), i.e., incorporating reductions in size, weight, and cost, are becoming available for civilian applications. Existing RPA programs are described and predicted into the future. Attention is given to the NASA Mini-Sniffer, which will fly to altitudes of more than 20,000 m, sample the atmosphere behind supersonic cruise aircraft, and telemeter the data to ground stations. Design and operating parameters of the aircraft are given, especially the optical sensing systems, and civilian RPA uses are outlined, including airborne research, remote mapping, rescue, message relay, and transportation of need materials. Civil regulatory factors are also dealt with.

Optical data communication for Earth observation satellite systems

NASA Astrophysics Data System (ADS)

Fischer, J.; Loecherbach, E.

1991-10-01

The current development status of optical communication engineering in comparison to the conventional microwave systems and the different configurations of the optical data communication for Earth observation satellite systems are described. An outlook to future optical communication satellite systems is given. During the last decade Earth observation became more and more important for the extension of the knowledge about our planet and the human influence on nature. Today pictures taken by satellites are used, for example, to discover mineral resources or to predict harvest, crops, climate, and environment variations and their influence on the population. A new and up to date application for Earth observation satellites can be the verification of disarmament arrangements and the control of crises areas. To solve these tasks a system of Earth observing satellites with sensors tailored to the envisaged mission is necessary. Besides these low Earth orbiting satellites, a global Earth observation system consists of at least two data relay satellites. The communication between the satellites will be established via Inter-Satellite Links (ISL) and Inter-Orbit Links (IOL). On these links, bitrates up to 1 Gbit/s must be taken into account. Due to the increasing scarcity of suitable frequencies, higher carrier frequencies must probably be considered, and possible interference with terrestrial radio relay systems are two main problems for a realization in microwave technique. One important step to tackle these problems is the use of optical frequencies for IOL's and ISL's.

Using remote sensing to predict earthquake impacts

NASA Astrophysics Data System (ADS)

Fylaktos, Asimakis; Yfantidou, Anastasia

2017-09-01

Natural hazards like earthquakes can result to enormous property damage, and human casualties in mountainous areas. Italy has always been exposed to numerous earthquakes, mostly concentrated in central and southern regions. Last year, two seismic events near Norcia (central Italy) have occurred, which led to substantial loss of life and extensive damage to properties, infrastructure and cultural heritage. This research utilizes remote sensing products and GIS software, to provide a database of information. We used both SAR images of Sentinel 1A and optical imagery of Landsat 8 to examine the differences of topography with the aid of the multi temporal monitoring technique. This technique suits for the observation of any surface deformation. This database is a cluster of information regarding the consequences of the earthquakes in groups, such as property and infrastructure damage, regional rifts, cultivation loss, landslides and surface deformations amongst others, all mapped on GIS software. Relevant organizations can implement these data in order to calculate the financial impact of these types of earthquakes. In the future, we can enrich this database including more regions and enhance the variety of its applications. For instance, we could predict the future impacts of any type of earthquake in several areas, and design a preliminarily model of emergency for immediate evacuation and quick recovery response. It is important to know how the surface moves, in particular geographical regions like Italy, Cyprus and Greece, where earthquakes are so frequent. We are not able to predict earthquakes, but using data from this research, we may assess the damage that could be caused in the future.

Permeability of the blood-brain barrier predicts conversion from optic neuritis to multiple sclerosis.

PubMed

Cramer, Stig P; Modvig, Signe; Simonsen, Helle J; Frederiksen, Jette L; Larsson, Henrik B W

2015-09-01

Optic neuritis is an acute inflammatory condition that is highly associated with multiple sclerosis. Currently, the best predictor of future development of multiple sclerosis is the number of T2 lesions visualized by magnetic resonance imaging. Previous research has found abnormalities in the permeability of the blood-brain barrier in normal-appearing white matter of patients with multiple sclerosis and here, for the first time, we present a study on the capability of blood-brain barrier permeability in predicting conversion from optic neuritis to multiple sclerosis and a direct comparison with cerebrospinal fluid markers of inflammation, cellular trafficking and blood-brain barrier breakdown. To this end, we applied dynamic contrast-enhanced magnetic resonance imaging at 3 T to measure blood-brain barrier permeability in 39 patients with monosymptomatic optic neuritis, all referred for imaging as part of the diagnostic work-up at time of diagnosis. Eighteen healthy controls were included for comparison. Patients had magnetic resonance imaging and lumbar puncture performed within 4 weeks of onset of optic neuritis. Information on multiple sclerosis conversion was acquired from hospital records 2 years after optic neuritis onset. Logistic regression analysis showed that baseline permeability in normal-appearing white matter significantly improved prediction of multiple sclerosis conversion (according to the 2010 revised McDonald diagnostic criteria) within 2 years compared to T2 lesion count alone. There was no correlation between permeability and T2 lesion count. An increase in permeability in normal-appearing white matter of 0.1 ml/100 g/min increased the risk of multiple sclerosis 8.5 times whereas having more than nine T2 lesions increased the risk 52.6 times. Receiver operating characteristic curve analysis of permeability in normal-appearing white matter gave a cut-off of 0.13 ml/100 g/min, which predicted conversion to multiple sclerosis with a sensitivity of 88% and specificity of 72%. We found a significant correlation between permeability and the leucocyte count in cerebrospinal fluid as well as levels of CXCL10 and MMP9 in the cerebrospinal fluid. These findings suggest that blood-brain barrier permeability, as measured by magnetic resonance imaging, may provide novel pathological information as a marker of neuroinflammation related to multiple sclerosis, to some extent reflecting cellular permeability of the blood-brain barrier, whereas T2 lesion count may more reflect the length of the subclinical pre-relapse phase.See Naismith and Cross (doi:10.1093/brain/awv196) for a scientific commentary on this article. © The Author (2015). Published by Oxford University Press on behalf of the Guarantors of Brain.

Tight real-time synchronization of a microwave clock to an optical clock across a turbulent air path

PubMed Central

Bergeron, Hugo; Sinclair, Laura C.; Swann, William C.; Nelson, Craig W.; Deschênes, Jean-Daniel; Baumann, Esther; Giorgetta, Fabrizio R.; Coddington, Ian; Newbury, Nathan R.

2018-01-01

The ability to distribute the precise time and frequency from an optical clock to remote platforms could enable future precise navigation and sensing systems. Here we demonstrate tight, real-time synchronization of a remote microwave clock to a master optical clock over a turbulent 4-km open air path via optical two-way time-frequency transfer. Once synchronized, the 10-GHz frequency signals generated at each site agree to 10−14 at one second and below 10−17 at 1000 seconds. In addition, the two clock times are synchronized to ±13 fs over an 8-hour period. The ability to phase-synchronize 10-GHz signals across platforms supports future distributed coherent sensing, while the ability to time-synchronize multiple microwave-based clocks to a high-performance master optical clock supports future precision navigation/timing systems. PMID:29607352

Tight real-time synchronization of a microwave clock to an optical clock across a turbulent air path.

PubMed

Bergeron, Hugo; Sinclair, Laura C; Swann, William C; Nelson, Craig W; Deschênes, Jean-Daniel; Baumann, Esther; Giorgetta, Fabrizio R; Coddington, Ian; Newbury, Nathan R

2016-04-01

The ability to distribute the precise time and frequency from an optical clock to remote platforms could enable future precise navigation and sensing systems. Here we demonstrate tight, real-time synchronization of a remote microwave clock to a master optical clock over a turbulent 4-km open air path via optical two-way time-frequency transfer. Once synchronized, the 10-GHz frequency signals generated at each site agree to 10 -14 at one second and below 10 -17 at 1000 seconds. In addition, the two clock times are synchronized to ±13 fs over an 8-hour period. The ability to phase-synchronize 10-GHz signals across platforms supports future distributed coherent sensing, while the ability to time-synchronize multiple microwave-based clocks to a high-performance master optical clock supports future precision navigation/timing systems.

Radio Flares from Gamma-ray Bursts

NASA Astrophysics Data System (ADS)

Kopač, D.; Mundell, C. G.; Kobayashi, S.; Virgili, F. J.; Harrison, R.; Japelj, J.; Guidorzi, C.; Melandri, A.; Gomboc, A.

2015-06-01

We present predictions of centimeter and millimeter radio emission from reverse shocks (RSs) in the early afterglows of gamma-ray bursts (GRBs) with the goal of determining their detectability with current and future radio facilities. Using a range of GRB properties, such as peak optical brightness and time, isotropic equivalent gamma-ray energy, and redshift, we simulate radio light curves in a framework generalized for any circumburst medium structure and including a parameterization of the shell thickness regime that is more realistic than the simple assumption of thick- or thin-shell approximations. Building on earlier work by Mundell et al. and Melandri et al. in which the typical frequency of the RS was suggested to lie at radio rather than optical wavelengths at early times, we show that the brightest and most distinct RS radio signatures are detectable up to 0.1-1 day after the burst, emphasizing the need for rapid radio follow-up. Detection is easier for bursts with later optical peaks, high isotropic energies, lower circumburst medium densities, and at observing frequencies that are less prone to synchrotron self-absorption effects—typically above a few GHz. Given recent detections of polarized prompt gamma-ray and optical RS emission, we suggest that detection of polarized radio/millimeter emission will unambiguously confirm the presence of low-frequency RSs at early time.

Effects of Corrugated Temperature Sheets on Optical Propagation along Quasi-Horizontal Paths in the Stably Stratified Atmosphere

DTIC Science & Technology

2015-12-11

diameter) are consistent with theoretical predictions based on Taylor’s frozen- turbulence hypothesis and the geometrical - optics approximation. Short...theoretical predictions based on Taylor’s frozen- turbulence hypothesis and the geometrical - optics approximation. Short-term (less than a few seconds... turbulent , quasi-horizontal interfaces, or “sheets”. Collocated in- situ and optical field measurements conducted in the atmospheric surface layer

Cryogenic Optical Performance of a Light-weight Mirror Assembly for Future Space Astronomical Telescopes: Optical Test Results and Thermal Optical Model

NASA Technical Reports Server (NTRS)

Eng, Ron; Arnold, William; Baker, Markus A.; Bevan, Ryan M.; Carpenter, James R.; Effinger, Michael R.; Gaddy, Darrell E.; Goode, Brian K.; Kegley, Jeffrey R.; Hogue, William D.;

An integrated fiber-optic probe combined with support vector regression for fast estimation of optical properties of turbid media.

PubMed

Zhou, Yang; Fu, Xiaping; Ying, Yibin; Fang, Zhenhuan

2015-06-23

A fiber-optic probe system was developed to estimate the optical properties of turbid media based on spatially resolved diffuse reflectance. Because of the limitations in numerical calculation of radiative transfer equation (RTE), diffusion approximation (DA) and Monte Carlo simulations (MC), support vector regression (SVR) was introduced to model the relationship between diffuse reflectance values and optical properties. The SVR models of four collection fibers were trained by phantoms in calibration set with a wide range of optical properties which represented products of different applications, then the optical properties of phantoms in prediction set were predicted after an optimal searching on SVR models. The results indicated that the SVR model was capable of describing the relationship with little deviation in forward validation. The correlation coefficient (R) of reduced scattering coefficient μ'(s) and absorption coefficient μ(a) in the prediction set were 0.9907 and 0.9980, respectively. The root mean square errors of prediction (RMSEP) of μ'(s) and μ(a) in inverse validation were 0.411 cm(-1) and 0.338 cm(-1), respectively. The results indicated that the integrated fiber-optic probe system combined with SVR model were suitable for fast and accurate estimation of optical properties of turbid media based on spatially resolved diffuse reflectance. Copyright © 2015 Elsevier B.V. All rights reserved.

Optical coherence tomography in gastroenterology: a review and future outlook

NASA Astrophysics Data System (ADS)

Tsai, Tsung-Han; Leggett, Cadman L.; Trindade, Arvind J.; Sethi, Amrita; Swager, Anne-Fré; Joshi, Virendra; Bergman, Jacques J.; Mashimo, Hiroshi; Nishioka, Norman S.; Namati, Eman

2017-12-01

Optical coherence tomography (OCT) is an imaging technique optically analogous to ultrasound that can generate depth-resolved images with micrometer-scale resolution. Advances in fiber optics and miniaturized actuation technologies allow OCT imaging of the human body and further expand OCT utilization in applications including but not limited to cardiology and gastroenterology. This review article provides an overview of current OCT development and its clinical utility in the gastrointestinal tract, including disease detection/differentiation and endoscopic therapy guidance, as well as a discussion of its future applications.

The CubeSat Infrared Atmospheric Sounder (CIRAS): Demonstrating key technologies for a future constellation to improve temporal sampling

NASA Astrophysics Data System (ADS)

Pagano, T. S.

2016-12-01

Hyperspectral infrared sounding of the atmosphere has become a vital element in the observational system for weather forecast prediction at National Weather Prediction (NWP) centers worldwide. The NASA Atmospheric Infrared Sounder (AIRS) instrument was the pathfinder for the hyperspectral infrared observations and was designed to provide accurate atmospheric temperature and water vapor profile information in support of weather prediction. AIRS was launched in 2002 and continues to operate well. The Cross-track Infrared Sounder (CrIS) on the Suomi NPP satellite was launched in 2011 to continue the AIRS measurement record. CrIS also continues to operate well and additional sensors are planned for launch promising to continue the hyperspectral infrared measurements in support of NWP into the late 2030's. The high cost of IR sounders makes it costly to launch them into multiple orbits to improve temporal sampling, or into GEO, although EUMETSAT is planning a GEO IR Sounder to launch in the early 2020's. JPL NASA is offering an alternate hyperspectral IR sounder architecture for the future involving CubeSats. The latest technology in large format focal plane assemblies, wide field optics and active cryocoolers enables a reduction in size, mass and cost of the legacy sounders and offer new configurations. Lessons learned from AIRS and CrIS indicate that temperature and water vapor sounding in the lower troposphere can be achieved with only the MWIR portion of the spectrum. The CubeSat Infrared Atmospheric Sounder (CIRAS) employs only an MWIR spectrometer to achieve lower tropospheric temperature and water vapor profiles, but with comparable spatial, spectral and radiometric sensitivity in this band as AIRS and CrIS. CIRAS operates from 4.08-5.13 µm with 625 channels and spectral resolution of 1.2-2.0 cm-1. CIRAS employs an immersion grating spectrometer making the optics incredibly compact, and HOT-BIRD detectors enabling good uniformity and operability over the large 512 x 640 element focal plane. The CIRAS is packaged in a 6U CubeSat and uses less than 14 W. This presentation will discuss the requirements, expected performance and state of development of the CIRAS and concepts for future space architectures. Technology advancements and retrieved product accuracy will also be included.

Three-dimensional (3D) evaluation of liquid distribution in shake flask using an optical fluorescence technique.

PubMed

Azizan, Amizon; Büchs, Jochen

2017-01-01

Biotechnological development in shake flask necessitates vital engineering parameters e.g. volumetric power input, mixing time, gas liquid mass transfer coefficient, hydromechanical stress and effective shear rate. Determination and optimization of these parameters through experiments are labor-intensive and time-consuming. Computational Fluid Dynamics (CFD) provides the ability to predict and validate these parameters in bioprocess engineering. This work provides ample experimental data which are easily accessible for future validations to represent the hydrodynamics of the fluid flow in the shake flask. A non-invasive measuring technique using an optical fluorescence method was developed for shake flasks containing a fluorescent solution with a waterlike viscosity at varying filling volume (V L  = 15 to 40 mL) and shaking frequency ( n  = 150 to 450 rpm) at a constant shaking diameter (d o  = 25 mm). The method detected the leading edge (LB) and tail of the rotating bulk liquid (TB) relative to the direction of the centrifugal acceleration at varying circumferential heights from the base of the shake flask. The determined LB and TB points were translated into three-dimensional (3D) circumferential liquid distribution plots. The maximum liquid height (H max ) of the bulk liquid increased with increasing filling volume and shaking frequency of the shaking flask, as expected. The toroidal shapes of LB and TB are clearly asymmetrical and the measured TB differed by the elongation of the liquid particularly towards the torus part of the shake flask. The 3D liquid distribution data collected at varying filling volume and shaking frequency, comprising of LB and TB values relative to the direction of the centrifugal acceleration are essential for validating future numerical solutions using CFD to predict vital engineering parameters in shake flask.

Optical glucose monitoring using vertical cavity surface emitting lasers (VCSELs)

NASA Astrophysics Data System (ADS)

Talebi Fard, Sahba; Hofmann, Werner; Talebi Fard, Pouria; Kwok, Ezra; Amann, Markus-Christian; Chrostowski, Lukas

2009-08-01

Diabetes Mellitus is a common chronic disease that has become a public health issue. Continuous glucose monitoring improves patient health by stabilizing the glucose levels. Optical methods are one of the painless and promising methods that can be used for blood glucose predictions. However, having accuracies lower than what is acceptable clinically has been a major concern. Using lasers along with multivariate techniques such as Partial Least Square (PLS) can improve glucose predictions. This research involves investigations for developing a novel optical system for accurate glucose predictions, which leads to the development of a small, low power, implantable optical sensor for diabetes patients.

Electro-Optic Computing Architectures. Volume I

DTIC Science & Technology

1998-02-01

The objective of the Electro - Optic Computing Architecture (EOCA) program was to develop multi-function electro - optic interfaces and optical...interconnect units to enhance the performance of parallel processor systems and form the building blocks for future electro - optic computing architectures...Specifically, three multi-function interface modules were targeted for development - an Electro - Optic Interface (EOI), an Optical Interconnection Unit (OW

Rigorous diffraction analysis using geometrical theory of diffraction for future mask technology

NASA Astrophysics Data System (ADS)

Chua, Gek S.; Tay, Cho J.; Quan, Chenggen; Lin, Qunying

2004-05-01

Advanced lithographic techniques such as phase shift masks (PSM) and optical proximity correction (OPC) result in a more complex mask design and technology. In contrast to the binary masks, which have only transparent and nontransparent regions, phase shift masks also take into consideration transparent features with a different optical thickness and a modified phase of the transmitted light. PSM are well-known to show prominent diffraction effects, which cannot be described by the assumption of an infinitely thin mask (Kirchhoff approach) that is used in many commercial photolithography simulators. A correct prediction of sidelobe printability, process windows and linearity of OPC masks require the application of rigorous diffraction theory. The problem of aerial image intensity imbalance through focus with alternating Phase Shift Masks (altPSMs) is performed and compared between a time-domain finite-difference (TDFD) algorithm (TEMPEST) and Geometrical theory of diffraction (GTD). Using GTD, with the solution to the canonical problems, we obtained a relationship between the edge on the mask and the disturbance in image space. The main interest is to develop useful formulations that can be readily applied to solve rigorous diffraction for future mask technology. Analysis of rigorous diffraction effects for altPSMs using GTD approach will be discussed.

Optical spectral signatures of liquids by means of fiber optic technology for product and quality parameter identification

NASA Astrophysics Data System (ADS)

Mignani, A. G.; Ciaccheri, L.; Mencaglia, A. A.; Diaz-Herrera, N.; Garcia-Allende, P. B.; Ottevaere, H.; Thienpont, H.; Attilio, C.; Cimato, A.; Francalanci, S.; Paccagnini, A.; Pavone, F. S.

2009-01-01

Absorption spectroscopy in the wide 200-1700 nm spectral range is carried out by means of optical fiber instrumentation to achieve a digital mapping of liquids for the prediction of important quality parameters. Extra virgin olive oils from Italy and lubricant oils from turbines with different degrees of degradation were considered as "case studies". The spectral data were processed by means of multivariate analysis so as to obtain a correlation to quality parameters. In practice, the wide range absorption spectra were considered as an optical signature of the liquids from which to extract product quality information. The optical signatures of extra virgin olive oils were used to predict the content of the most important fatty acids. The optical signatures of lubricant oils were used to predict the concentration of the most important parameters for indicating the oil's degree of degradation, such as TAN, JOAP anti-wear index, and water content.

Optical and biometric relationships of the isolated pig crystalline lens.

PubMed

Vilupuru, A S; Glasser, A

2001-07-01

To investigate the interrelationships between optical and biometric properties of the porcine crystalline lens, to compare these findings with similar relationships found for the human lens and to attempt to fit this data to a geometric model of the optical and biometric properties of the pig lens. Weight, focal length, spherical aberration, surface curvatures, thickness and diameters of 20 isolated pig lenses were measured and equivalent refractive index was calculated. These parameters were compared and used to geometrically model the pig lens. Linear relationships were identified between many of the lens biometric and optical properties. The existence of these relationships allowed a simple geometrical model of the pig lens to be calculated which offers predictions of the optical properties. The linear relationships found and the agreement observed between measured and modeled results suggest that the pig lens confirms to a predictable, preset developmental pattern and that the optical and biometric properties are predictably interrelated.

Analysis of blocking probability for OFDM-based variable bandwidth optical network

NASA Astrophysics Data System (ADS)

Gong, Lei; Zhang, Jie; Zhao, Yongli; Lin, Xuefeng; Wu, Yuyao; Gu, Wanyi

2011-12-01

Orthogonal Frequency Division Multiplexing (OFDM) has recently been proposed as a modulation technique. For optical networks, because of its good spectral efficiency, flexibility, and tolerance to impairments, optical OFDM is much more flexible compared to traditional WDM systems, enabling elastic bandwidth transmissions, and optical networking is the future trend of development. In OFDM-based optical network the research of blocking rate has very important significance for network assessment. Current research for WDM network is basically based on a fixed bandwidth, in order to accommodate the future business and the fast-changing development of optical network, our study is based on variable bandwidth OFDM-based optical networks. We apply the mathematical analysis and theoretical derivation, based on the existing theory and algorithms, research blocking probability of the variable bandwidth of optical network, and then we will build a model for blocking probability.

High Accuracy Ground-based near-Earth-asteroid Astrometry using Synthetic Tracking

NASA Astrophysics Data System (ADS)

Zhai, Chengxing; Shao, Michael; Saini, Navtej; Sandhu, Jagmit; Werne, Thomas; Choi, Philip; Ely, Todd A.; Jacobs, Chirstopher S.; Lazio, Joseph; Martin-Mur, Tomas J.; Owen, William M.; Preston, Robert; Turyshev, Slava; Michell, Adam; Nazli, Kutay; Cui, Isaac; Monchama, Rachel

2018-01-01

Accurate astrometry is crucial for determining the orbits of near-Earth-asteroids (NEAs). Further, the future of deep space high data rate communications is likely to be optical communications, such as the Deep Space Optical Communications package that is part of the baseline payload for the planned Psyche Discovery mission to the Psyche asteroid. We have recently upgraded our instrument on the Pomona College 1 m telescope, at JPL's Table Mountain Facility, for conducting synthetic tracking by taking many short exposure images. These images can be then combined in post-processing to track both asteroid and reference stars to yield accurate astrometry. Utilizing the precision of the current and future Gaia data releases, the JPL-Pomona College effort is now demonstrating precision astrometry on NEAs, which is likely to be of considerable value for cataloging NEAs. Further, treating NEAs as proxies of future spacecraft that carry optical communication lasers, our results serve as a measure of the astrometric accuracy that could be achieved for future plane-of-sky optical navigation.

High Accuracy Ground-based near-Earth-asteroid Astrometry using Synthetic Tracking

NASA Astrophysics Data System (ADS)

Zhai, C.; Shao, M.; Saini, N. S.; Sandhu, J. S.; Werne, T. A.; Choi, P.; Ely, T. A.; Jacobs, C.; Lazio, J.; Martin-Mur, T. J.; Owen, W. K.; Preston, R. A.; Turyshev, S. G.

2017-12-01

Accurate astrometry is crucial for determining the orbits of near-Earth-asteroids (NEAs). Further, the future of deep space high data rate communications is likely to be optical communications, such as the Deep Space Optical Communications package to be carried on the Psyche Discovery mission to the Psyche asteroid. We have recently upgraded our instrument on the Pomona College 1 m telescope, at JPL's Table Mountain Facility, for conducting synthetic tracking by taking many short exposure images. These images can be then combined in post-processing to track both asteroid and reference stars to yield accurate astrometry. Utilizing the precision of the current and future Gaia data releases, the JPL-Pomona College effort is now demonstrating precision astrometry on NEAs, which is likely to be of considerable value for cataloging NEAs. Further, treating NEAs as proxies of future spacecraft that carry optical communication lasers, our results serve as a measure of the astrometric accuracy that could be achieved for future plane-of-sky optical navigation.

Contamination Effects on EUV Optics

NASA Technical Reports Server (NTRS)

Tveekrem, J.

1999-01-01

During ground-based assembly and upon exposure to the space environment, optical surfaces accumulate both particles and molecular condensibles, inevitably resulting in degradation of optical instrument performance. Currently, this performance degradation (and the resulting end-of-life instrument performance) cannot be predicted with sufficient accuracy using existing software tools. Optical design codes exist to calculate instrument performance, but these codes generally assume uncontaminated optical surfaces. Contamination models exist which predict approximate end-of-life contamination levels, but the optical effects of these contamination levels can not be quantified without detailed information about the optical constants and scattering properties of the contaminant. The problem is particularly pronounced in the extreme ultraviolet (EUV, 300-1,200 A) and far (FUV, 1,200-2,000 A) regimes due to a lack of data and a lack of knowledge of the detailed physical and chemical processes involved. Yet it is in precisely these wavelength regimes that accurate predictions are most important, because EUV/FUV instruments are extremely sensitive to contamination.

The Physics of Boundary-Layer Aero-Optic Effects

DTIC Science & Technology

2012-09-01

various models to predict aero-optical effects for both subsonic and supersonic Mach numbers, laser beam sizes and non- adiabatic walls. The developed...models to predict aero-optical effects for both subsonic and supersonic Mach numbers, laser beam sizes and non- adiabatic walls. The developed models were... Supersonic Facilities .................................................................................................... 8 3.3 2-D Wavefront Data

Integrated Optics: A Technology With A Future

NASA Astrophysics Data System (ADS)

Miller, Stewart E.

1985-01-01

If I were in the audience, listening to this talk, I am sure I would like to hear answers to questions such as: 'here is Integrated Optics going? What should I do to capitalize on this future? How soon will this market grow? What products will be needed?

Roadmap on silicon photonics

NASA Astrophysics Data System (ADS)

Thomson, David; Zilkie, Aaron; Bowers, John E.; Komljenovic, Tin; Reed, Graham T.; Vivien, Laurent; Marris-Morini, Delphine; Cassan, Eric; Virot, Léopold; Fédéli, Jean-Marc; Hartmann, Jean-Michel; Schmid, Jens H.; Xu, Dan-Xia; Boeuf, Frédéric; O'Brien, Peter; Mashanovich, Goran Z.; Nedeljkovic, M.

2016-07-01

Silicon photonics research can be dated back to the 1980s. However, the previous decade has witnessed an explosive growth in the field. Silicon photonics is a disruptive technology that is poised to revolutionize a number of application areas, for example, data centers, high-performance computing and sensing. The key driving force behind silicon photonics is the ability to use CMOS-like fabrication resulting in high-volume production at low cost. This is a key enabling factor for bringing photonics to a range of technology areas where the costs of implementation using traditional photonic elements such as those used for the telecommunications industry would be prohibitive. Silicon does however have a number of shortcomings as a photonic material. In its basic form it is not an ideal material in which to produce light sources, optical modulators or photodetectors for example. A wealth of research effort from both academia and industry in recent years has fueled the demonstration of multiple solutions to these and other problems, and as time progresses new approaches are increasingly being conceived. It is clear that silicon photonics has a bright future. However, with a growing number of approaches available, what will the silicon photonic integrated circuit of the future look like? This roadmap on silicon photonics delves into the different technology and application areas of the field giving an insight into the state-of-the-art as well as current and future challenges faced by researchers worldwide. Contributions authored by experts from both industry and academia provide an overview and outlook for the silicon waveguide platform, optical sources, optical modulators, photodetectors, integration approaches, packaging, applications of silicon photonics and approaches required to satisfy applications at mid-infrared wavelengths. Advances in science and technology required to meet challenges faced by the field in each of these areas are also addressed together with predictions of where the field is destined to reach.

Cryogenic Optical Performance of a Lightweighted Mirror Assembly for Future Space Astronomical Telescopes: Correlating Optical Test Results and Thermal Optical Model

NASA Technical Reports Server (NTRS)

Eng, Ron; Arnold, William R.; Baker, Marcus A.; Bevan, Ryan M.; Burdick, Gregory; Effinger, Michael R.; Gaddy, Darrell E.; Goode, Brian K.; Hanson, Craig; Hogue, William D.;

Processing LiDAR Data to Predict Natural Hazards

NASA Technical Reports Server (NTRS)

Fairweather, Ian; Crabtree, Robert; Hager, Stacey

2008-01-01

ELF-Base and ELF-Hazards (wherein 'ELF' signifies 'Extract LiDAR Features' and 'LiDAR' signifies 'light detection and ranging') are developmental software modules for processing remote-sensing LiDAR data to identify past natural hazards (principally, landslides) and predict future ones. ELF-Base processes raw LiDAR data, including LiDAR intensity data that are often ignored in other software, to create digital terrain models (DTMs) and digital feature models (DFMs) with sub-meter accuracy. ELF-Hazards fuses raw LiDAR data, data from multispectral and hyperspectral optical images, and DTMs and DFMs generated by ELF-Base to generate hazard risk maps. Advanced algorithms in these software modules include line-enhancement and edge-detection algorithms, surface-characterization algorithms, and algorithms that implement innovative data-fusion techniques. The line-extraction and edge-detection algorithms enable users to locate such features as faults and landslide headwall scarps. Also implemented in this software are improved methodologies for identification and mapping of past landslide events by use of (1) accurate, ELF-derived surface characterizations and (2) three LiDAR/optical-data-fusion techniques: post-classification data fusion, maximum-likelihood estimation modeling, and hierarchical within-class discrimination. This software is expected to enable faster, more accurate forecasting of natural hazards than has previously been possible.

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.

FIBER OPTICS: Fibre optics: Forty years later

NASA Astrophysics Data System (ADS)

Dianov, Evgenii M.

2010-01-01

This paper presents a brief overview of the state of the art in fibre optics and its main applications: optical fibre communications, fibre lasers and fibre sensors for various physical property measurements. The future of fibre optics and the status of this important area of the modern technology in Russia are discussed.

Basics of Videodisc and Optical Disk Technology.

ERIC Educational Resources Information Center

Paris, Judith

1983-01-01

Outlines basic videodisc and optical disk technology describing both optical and capacitance videodisc technology. Optical disk technology is defined as a mass digital image and data storage device and briefly compared with other information storage media including magnetic tape and microforms. The future of videodisc and optical disk is…

Optical interference coatings for optics and photonics [Invited].

PubMed

Lee, Cheng-Chung

2013-01-01

Optical interference coatings play as an important role in the progress in optics and photonics. In this article we give a minireview of the evolution of optical interference coatings from the theory, the design, to the manufacture. Some interesting but challenging topics for the future are also discussed.

Fiber Optic Experience with the Smart Actuation System on the F-18 Systems Research Aircraft

NASA Technical Reports Server (NTRS)

Zavala, Eddie

1997-01-01

High bandwidth, immunity to electromagnetic interference, and potential weight savings have led to the development of fiber optic technology for future aerospace vehicle systems. This technology has been incorporated in a new smart actuator as the primary communication interface. The use of fiber optics simplified system integration and significantly reduced wire count. Flight test results showed that fiber optics could be used in aircraft systems and identified critical areas of development of fly-by-light technology. This paper documents the fiber optic experience gained as a result of this program, and identifies general design considerations that could be used in a variety of specific applications of fiber optic technology. Environmental sensitivities of fiber optic system components that significantly contribute to optical power variation are discussed. Although a calibration procedure successfully minimized the effect of fiber optic sensitivities, more standardized calibration methods are needed to ensure system operation and reliability in future aerospace vehicle systems.

Optical distribution of local oscillators in future telecommunication satellite payloads

NASA Astrophysics Data System (ADS)

Benazet, Benoît; Sotom, Michel; Maignan, Michel; Berthon, Jacques

2017-11-01

The distribution of high spectral purity reference signals over optical fibre in future telecommunication satellite payloads is presented. Several types of applications are considered, including the distribution of a reference frequency at 10 MHz (Ultra-Stable Reference Oscillator) as well as the distribution of a radiofrequency oscillator around 800 MHz (Master Local Oscillator). The results of both experimental and theoretical studies are reported. In order to meet phase noise requirements for the USRO distribution, the use of an optimised receiver circuit based on an optically synchronised oscillator is investigated. Finally, the optical distribution of microwave local oscillators at frequencies exceeding 20 GHz is described. Such a scheme paves the way to more advanced sub-systems involving optical frequency-mixing and optical transmission of microwave signals, with applications to multiple-beam active antennas.

Polymer Optical Fiber Sensor and the Prediction of Sensor Response Utilizing Artificial Neural Networks

NASA Astrophysics Data System (ADS)

Haroglu, Derya

The global market researches showed that there is a growing trend in the field of polymer optical fiber (POF) and POF sensors. Telecommunications, medicine, defense, aerospace, and automotive are the application areas of fiber optic sensors, where the automotive industry is the most promising application area for innovations in the field of POF sensors. The POF sensors in automobiles are particularly for detection of seat occupancy, and intelligent pedestrian protection systems. This dissertation investigates graded index perfluorinated polymer optical fiber as an intensity modulated intrinsic sensor for application in automotive seat occupancy sensing. Since a fiber optic sensor has a high bandwidth, is small in size, is lightweight, and is immune to electromagnetic interference (EMI) it offers higher performance than that of its electrical based counterparts such as strain gauge, elastomeric bladder, and resistive sensor systems. This makes the fiber optic sensor a potential suitable material for seat occupancy sensing. A textile-based fiber optic sensor was designed to be located in the area beneath the typical seated human's thighs. The pressure interval under which the proposed POF sensor design could perform well was found to be between 0.18 and 0.21 N/cm2, where perfluorinated (PF) graded index (GI) POF (62.5/750 mum) was used as the POF material. In addition, the effect of the automotive seat covering including face material (fabric) and foam backing to the sensor's performance was analyzed. The face fabric structure and the thickness of foam backing were not found to be significant factors to change the sensor results. A research study, survey, was conducted of which purpose was to better understand market demands in terms of sensor performance characteristics for automotive seat weight sensors, as a part of the Quality Function Deployment (QFD) House of Quality analysis. The companies joined the survey agreed on the first 5 most important sensor characteristics: reproducibility, accuracy, selectivity, aging, and resolution. Artificial neural network (ANN), a mathematical model formed by mimicking the human nervous system, was used to predict the sensor response. Qwiknet (version 2.23) software was used to develop ANNs and according to the results of Qwiknet the prediction performances for training and testing data sets were 75%, and 83.33% respectively. In this dissertation, Chapter 1 describes the worldwide plastic optical fiber (POF) and fiber optic sensor markets, and the existing textile structures used in fiber optic sensing design particularly for the applications of biomedical and structural health monitoring (SHM). Chapter 2 provides a literature review in detail on polymer optical fibers, fiber optic sensors, and occupancy sensing in the passenger seats of automobiles. Chapter 3 includes the research objectives. Chapter 4 presents the response of POF to tensile loading, bending, and cyclic tensile loading with discussion parts. Chapter 5 includes an e-mail based survey to prioritize customer needs in a Quality Function Deployment (QFD) format utilizing Analytic Hierarchy Process (AHP) and survey results. Chapter 6 describes the POF sensor design and the behavior of it under pressure. Chapter 7 provides a data analysis based on the experimental results of Chapter 6. Chapter 8 presents the summary of this study and recommendations for future work.

Gbit/s-operation of graphene electro-absorption modulators in a passive polymer waveguide platform for data and telecommunications

NASA Astrophysics Data System (ADS)

Kleinert, M.; Reinke, P.; Bach, H.-G.; Brinker, W.; Zawadzki, C.; Dietrich, A.; de Felipe, D.; Keil, N.; Schell, M.

2017-02-01

Graphene with its high carrier mobility as well as its tunable light absorption is an attractive active material for highspeed electro-absorption modulators (EAMs). Large-area CVD-grown graphene monolayers can be transferred onto arbitrary substrates to add active optoelectronic properties to intrinsically passive photonic integration platforms. In this work, we present graphene-based EAMs integrated in passive polymer waveguides. To facilitate modulation frequencies in the GHz range, a 50 Ω termination resistor as well as a DC blocking capacitor are integrated with graphene EAMs for the first time. Large signal data transmission experiments were carried out across the O, C and L optical communications bands. The fastest devices exhibit a 3-dB bandwidth of more than 4 GHz. Our analytical model of the modulation response for the graphene-based EAMs is in good agreement with the measurement results. It predicts that bandwidths greater than 50 GHz are possible with future device iterations. Owing to the absorption properties of the graphene layers, the devices are expected to be functional at smaller wavelengths of interest for optical interconnects and data-communications as well, offering a novel flexibility for the integration of high-speed functionalities in optoelectronic integrated circuits. Our work is the first step towards an Active Optical Printed Circuit Board, hiding the optics completely inside the board and thus removing entry barriers in manufacturing. We believe this will lead to the same success as observed in Active Optical Cables for short range optically wired connections.

Predicting silicon pore optics

NASA Astrophysics Data System (ADS)

Vacanti, Giuseppe; Barriére, Nicolas; Bavdaz, Marcos; Chatbi, Abdelhakim; Collon, Maximilien; Dekker, Danielle; Girou, David; Günther, Ramses; van der Hoeven, Roy; Landgraf, Boris; Sforzini, Jessica; Vervest, Mark; Wille, Eric

2017-09-01

Continuing improvement of Silicon Pore Optics (SPO) calls for regular extension and validation of the tools used to model and predict their X-ray performance. In this paper we present an updated geometrical model for the SPO optics and describe how we make use of the surface metrology collected during each of the SPO manufacturing runs. The new geometrical model affords the user a finer degree of control on the mechanical details of the SPO stacks, while a standard interface has been developed to make use of any type of metrology that can return changes in the local surface normal of the reflecting surfaces. Comparisons between the predicted and actual performance of samples optics will be shown and discussed.

Design and Performance of the Terrestrial Planet Finder Coronagraph

NASA Technical Reports Server (NTRS)

White, Mary L.; Shaklan, Stuart; Lisman, P. Doulas; Ho, Timothy; Mouroulis, Pantazis; Basinger, Scott; Ledeboer, Bill; Kwack, Eug; Kissil, Andy; Mosier, Gary;

Exploring the use of optical flow for the study of functional NIRS signals

NASA Astrophysics Data System (ADS)

Fernandez Rojas, Raul; Huang, Xu; Ou, Keng-Liang; Hernandez-Juarez, Jesus

2017-03-01

Near infrared spectroscopy (NIRS) is an optical imaging technique that allows real-time measurements of Oxy and Deoxy-hemoglobin concentrations in human body tissue. In functional NIRS (fNIRS), this technique is used to study cortical activation in response to changes in neural activity. However, analysis of activation regions using NIRS is a challenging task in the field of medical image analysis and despite existing solutions, no homogeneous analysis method has yet been determined. For that reason, the aim of our present study is to report the use of an optical flow method for the analysis of cortical activation using near-infrared spectroscopy signals. We used real fNIRS data recorded from a noxious stimulation experiment as base of our implementation. To compute the optical flow algorithm, we first arrange NIRS signals (Oxy-hemoglobin) following our 24 channels (12 channels per hemisphere) head-probe configuration to create image-like samples. We then used two consecutive fNIRS samples per hemisphere as input frames for the optical flow algorithm, making one computation per hemisphere. The output from these two computations is the velocity field representing cortical activation from each hemisphere. The experimental results showed that the radial structure of flow vectors exhibited the origin of cortical activity, the development of stimulation as expansion or contraction of such flow vectors, and the flow of activation patterns may suggest prediction in cortical activity. The present study demonstrates that optical flow provides a power tool for the analysis of NIRS signals. Finally, we suggested a novel idea to identify pain status in nonverbal patients by using optical flow motion vectors; however, this idea will be study further in our future research.

The Blazar 3C 66A in 2003-2004: hadronic versus leptonic model fits

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

Reimer, A.; Joshi, M.; Boettcher, M.

2008-12-24

The low-frequency peaked BL Lac object 3C 66A was the subject of an extensive multi-wavelength campaign from July 2003 till April 2004, which included quasi-simultaneous observations at optical, X-rays and very high energy gamma-rays. Here we apply the hadronic Synchrotron-Proton Blazar (SPB) model to the observed spectral energy distribution time-averaged over a flaring state, and compare the resulting model fits to those obtained from the application of the leptonic Synchrotron-Self-Compton (SSC) model. The results are used to identify diagnostic key predictions of the two blazar models for future multi-wavelength observations.

The Predictive Power of Electronic Polarizability for Tailoring the Refractivity of High Index Glasses Optical Basicity Versus the Single Oscillator Model

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

McCloy, John S.; Riley, Brian J.; Johnson, Bradley R.

Four compositions of high density (~8 g/cm3) heavy metal oxide glasses composed of PbO, Bi2O3, and Ga2O3 were produced and refractivity parameters (refractive index and density) were computed and measured. Optical basicity was computed using three different models – average electronegativity, ionic-covalent parameter, and energy gap – and the basicity results were used to compute oxygen polarizability and subsequently refractive index. Refractive indices were measured in the visible and infrared at 0.633 μm, 1.55 μm, 3.39 μm, 5.35 μm, 9.29 μm, and 10.59 μm using a unique prism coupler setup, and data were fitted to the Sellmeier expression to obtainmore » an equation of the dispersion of refractive index with wavelength. Using this dispersion relation, single oscillator energy, dispersion energy, and lattice energy were determined. Oscillator parameters were also calculated for the various glasses from their oxide values as an additional means of predicting index. Calculated dispersion parameters from oxides underestimate the index by 3 to 4%. Predicted glass index from optical basicity, based on component oxide energy gaps, underpredicts the index at 0.633 μm by only 2%, while other basicity scales are less accurate. The predicted energy gap of the glasses based on this optical basicity overpredicts the Tauc optical gap as determined by transmission measurements by 6 to 10%. These results show that for this system, density, refractive index in the visible, and energy gap can be reasonably predicted using only composition, optical basicity values for the constituent oxides, and partial molar volume coefficients. Calculations such as these are useful for a priori prediction of optical properties of glasses.« less

Optical ground station optimization for future optical geostationary satellite feeder uplinks

NASA Astrophysics Data System (ADS)

Camboulives, A.-R.; Velluet, M.-T.; Poulenard, S.; Saint-Antonin, L.; Michau, V.

2017-02-01

An optical link based on a multiplex of wavelengths at 1:55 μm is foreseen to be a valuable alternative to the conventional radio-frequencies for the feeder link of the next-generation of high throughput geostationary satellite. Considering the limited power of lasers envisioned for feeder links, the beam divergence has to be dramatically reduced. Consequently, the beam pointing becomes a key issue. During its propagation between the ground station and a geostationary satellite, the optical beam is deflected (beam wandering), and possibly distorted (beam spreading), by atmospheric turbulence. It induces strong fluctuations of the detected telecom signal, thus increasing the bit error rate (BER). A steering mirror using a measurement from a beam coming from the satellite is used to pre-compensate the deflection. Because of the point-ahead angle between the downlink and the uplink, the turbulence effects experienced by both beams are slightly different, inducing an error in the correction. This error is characterized as a function of the turbulence characteristics as well as of the terminal characteristics, such as the servo-loop bandwidth or the beam diameter, and is included in the link budget. From this result, it is possible to predict intensity fluctuations detected by the satellite statistically (mean intensity, scintillation index, probability of fade, etc.)). The final objective is to optimize the different parameters of an optical ground station capable of mitigating the impact of atmospheric turbulence on the uplink in order to be compliant with the targeted capacity (1Terabit/s by 2025).

Quantum phases in circuit QED with a superconducting qubit array

PubMed Central

Zhang, Yuanwei; Yu, Lixian; Liang, J. -Q; Chen, Gang; Jia, Suotang; Nori, Franco

2014-01-01

Circuit QED on a chip has become a powerful platform for simulating complex many-body physics. In this report, we realize a Dicke-Ising model with an antiferromagnetic nearest-neighbor spin-spin interaction in circuit QED with a superconducting qubit array. We show that this system exhibits a competition between the collective spin-photon interaction and the antiferromagnetic nearest-neighbor spin-spin interaction, and then predict four quantum phases, including: a paramagnetic normal phase, an antiferromagnetic normal phase, a paramagnetic superradiant phase, and an antiferromagnetic superradiant phase. The antiferromagnetic normal phase and the antiferromagnetic superradiant phase are new phases in many-body quantum optics. In the antiferromagnetic superradiant phase, both the antiferromagnetic and superradiant orders can coexist, and thus the system possesses symmetry. Moreover, we find an unconventional photon signature in this phase. In future experiments, these predicted quantum phases could be distinguished by detecting both the mean-photon number and the magnetization. PMID:24522250

Electro-Optic Computing Architectures: Volume II. Components and System Design and Analysis

DTIC Science & Technology

1998-02-01

The objective of the Electro - Optic Computing Architecture (EOCA) program was to develop multi-function electro - optic interfaces and optical...interconnect units to enhance the performance of parallel processor systems and form the building blocks for future electro - optic computing architectures...Specifically, three multi-function interface modules were targeted for development - an Electro - Optic Interface (EOI), an Optical Interconnection Unit

Buying Fiber-Optic Networks.

ERIC Educational Resources Information Center

Fickes, Michael

2003-01-01

Describes consortia formed by college and university administrators to buy, manage, and maintain their own fiber-optic networks with the goals of cutting costs of leasing fiber-optic cable and planning for the future. Growth capacity is the real advantage of owning fiber-optic systems. (SLD)

Optical Information Processing for Aerospace Applications

NASA Technical Reports Server (NTRS)

1981-01-01

Current research in optical processing is reviewed. Its role in future aerospace systems is determined. The development of optical devices and components demonstrates that system concepts can be implemented in practical aerospace configurations.

Fiberoptics technology and its application to propulsion control systems

NASA Technical Reports Server (NTRS)

Baumbick, R. J.

1983-01-01

Electro-optical systems have many advantages over conventional electrical systems. Among these are optics' insensitivity to electro-magnetic interference, good electrical isolation and the ability to make measurements in highly explosive areas without risk. These advantages promise to help improve the reliability of future aircraft engine control systems which will be entirely electronic digital. To improve the reliability of these systems, especially against lightning strikes, passive, optical, sensors and fiberoptic transmission lines are being considered for use in future engine systems. Also under consideration are actuators which receive their command signals over fiber optic cables. This paper reviews concepts used for optical instrumentation and actuation systems and discusses work being done by NASA Lewis Research Center in this area.

Development of a Flyable Acousto-Optic Laser Beam Deflection System for a Head Up Display of the Future.

DTIC Science & Technology

Rayleigh criteria). The system was designed for stroke writing but was demonstrated with lissajous writing. The acousto - optic deflectors employed...The report describes a laser display which is to be used in a Head-Up Display of the future. The uniqueness of the display is that it uses acousto ... optic components for the modulation and deflection of the laser beam. As a result, there are no moving parts, which increases the reliability and life

Super-light-weighted HB-Cesic® mirror cryogenic test

NASA Astrophysics Data System (ADS)

Devilliers, Christophe; Krödel, Matthias R.; Sodnik, Zoran; Robert, Patrick

2017-11-01

Future scientific space missions require ever more demanding large optics that work at cryogenic temperatures. In the frame of a Darwin assessment study conducted under ESA contract by TAS, the need of future very lightweight cryogenic mirrors with superior optical quality has been identified. Such mirrors need to be of size up to 3.5 m in diameter, with a mass of less than 250 kg (i.e. 25 kg/m2) and possess excellent optical quality at cryogenic temperature down to 40 K.

Task one report: Optical system study. [characteristics of laser equipment for space communication systems

NASA Technical Reports Server (NTRS)

1973-01-01

An optical system which can be incorporated in a present day or near future space-borne laser communications system is described. Techniques of implementing these systems are presented and their design problems and use are discussed. Optical system weight is estimated as a function of aperture diameter for a typical present day or near future laser communication system. The optical communications system considered is a two-way, high data rate optical communications link from a spacecraft to a spacecraft or from a spacecraft to a ground station. Each station has a laser transmitter and receiver and a pointing and tracking system. Thus each station can track the laser transmitter of the other. Optical beamwidths are considered to be as small as an arc-second with the beam pointed to a fraction of this beamwidth.

Surface plasmons based terahertz modulator consisting of silicon-air-metal-dielectric-metal layers

NASA Astrophysics Data System (ADS)

Wang, Wei; Yang, Dongxiao; Qian, Zhenhai

2018-05-01

An optically controlled modulator of the terahertz wave, which is composed of a metal-dielectric-metal structure etched with circular loop arrays on both the metal layers and a photoexcited silicon wafer separated by an air layer, is proposed. Simulation results based on experimentally measured complex permittivities predict that modification of complex permittivity of the silicon wafer through excitation laser leads to a significant tuning of transmission characteristics of the modulator, forming the modulation depths of 59.62% and 96.64% based on localized surface plasmon peak and propagating surface plasmon peak, respectively. The influences of the complex permittivity of the silicon wafer and the thicknesses of both the air layer and the silicon wafer are numerically studied for better understanding the modulation mechanism. This study proposes a feasible methodology to design an optically controlled terahertz modulator with large modulation depth, high speed and suitable insertion loss, which is useful for terahertz applications in the future.

Laboratory MCAO Test-Bed for Developing Wavefront Sensing Concepts.

PubMed

Goncharov, A V; Dainty, J C; Esposito, S; Puglisi, A

2005-07-11

An experimental optical bench test-bed for developing new wavefront sensing concepts for Multi-Conjugate Adaptive Optics (MCAO) systems is described. The main objective is to resolve imaging problems associated with wavefront sensing of the atmospheric turbulence for future MCAO systems on Extremely Large Telescopes (ELTs). The test-bed incorporates five reference sources, two deformable mirrors (DMs) and atmospheric phase screens to simulate a scaled version of a 10-m adaptive telescope operating at the K band. A recently proposed compact tomographic wavefront sensor is employed for star-oriented DMs control in the MCAO system. The MCAO test-bed is used to verify the feasibility of the wavefront sensing concept utilizing a field lenslet array for multi-pupil imaging on a single detector. First experimental results of MCAO correction with the proposed tomographic wavefront sensor are presented and compared to the theoretical prediction based on the characteristics of the phase screens, actuator density of the DMs and the guide star configuration.

Rapid Bead-Based Antimicrobial Susceptibility Testing by Optical Diffusometry

PubMed Central

Chung, Chih-Yao; Wang, Jhih-Cheng; Chuang, Han-Sheng

2016-01-01

This study combined optical diffusometry and bead-based immunoassays to develop a novel technique for quantifying the growth of specific microorganisms and achieving rapid AST. Diffusivity rises when live bacteria attach to particles, resulting in additional energy from motile microorganisms. However, when UV-sterilized (dead) bacteria attach to particles, diffusivity declines. The experimental data are consistent with the theoretical model predicted according to the equivalent volume diameter. Using this diffusometric platform, the susceptibility of Pseudomonas aeruginosa to the antibiotic gentamicin was tested. The result suggests that the proliferation of bacteria is effectively controlled by gentamicin. This study demonstrated a sensitive (one bacterium on single particles) and time-saving (within 2 h) platform with a small sample volume (~0.5 μL) and a low initial bacteria count (50 CFU per droplet ~ 105 CFU/mL) for quantifying the growth of microorganisms depending on Brownian motion. The technique can be applied further to other bacterial strains and increase the success of treatments against infectious diseases in the near future. PMID:26863001

Identifying OH Imposters in the ALFALFA HI Survey

NASA Astrophysics Data System (ADS)

Suess, Katherine; Darling, Jeremiah K.; Haynes, Martha P.; Giovanelli, Riccardo

2015-01-01

OH megamasers (OHMs) are rare, luminous molecular masers that are typically observed in (ultra) luminous infrared galaxies and serve as markers of major galaxy mergers. In blind emission line surveys such as the ALFALFA (Arecibo Legacy Fast Arecibo L-Band Feed Array) survey for neutral hydrogen (HI) in the local universe, OHMs at z~0.2 can mimic z~0.05 HI lines. We present the results of optical spectroscopy of ambiguous HI detections in the ALFALFA 40% data release [1] detected by WISE but with uncertain optical counterparts. The optical redshifts, obtained from observations at the Apache Point Observatory 3.5m telescope, identified 127 HI optical counterparts and discovered five new OHMs. Fifty-six candidates remain ambiguous. The new OHMs are the first detected in a blind spectral line survey.The number of OHMs in ALFALFA matches predictions based on the OH luminosity function [2]. Additionally, the OHMs found in a blind survey do not seem to differ from those found in previous targeted surveys. This provides validation of the methods used in previous IR-selected OHM surveys and indicates there is no previously unknown OHM-producing population at z~0.2. We also provide a method for future surveys to separate OH and HI lines without expensive spectral observations. This method utilizes infrared colors and magnitudes, such as WISE mid-IR data. Since the fraction of OHMs found in flux-limited HI surveys is expected to increase with the redshift of the survey [3], this analysis can be applied to future flux-limited high-redshift hydrogen surveys.We thank the ALFALFA team for observing and producing the survey dataset. The ALFALFA team at Cornell is supported by NSF AST-1107390 and the Brinson Foundation.[1] Haynes, M. P., R. Giovanelli, A. M. Martin, K. M. Hess, A. Saintonge, et al. 2011, Astron J, 142, 142[2] Darling, J. & R. Giovanelli 2002, Astrophys J, 572, 810[3] Briggs, F. H. 1998, A&A, 336, 815

Deriving the polarization behavior of many-layer mirror coatings

NASA Astrophysics Data System (ADS)

White, Amanda J.; Harrington, David M.; Sueoka, Stacey R.

2018-06-01

End-to-end models of astronomical instrument performance are becoming commonplace to demonstrate feasibility and guarantee performance at large observatories. Astronomical techniques like adaptive optics and high contrast imaging have made great strides towards making detailed performance predictions, however, for polarimetric techniques, fundamental tools for predicting performance do not exist. One big missing piece is predicting the wavelength and field of view dependence of a many-mirror articulated optical system particularly with complex protected metal coatings. Predicting polarization performance of instruments requires combining metrology of mirror coatings, tools to create mirror coating models, and optical modeling software for polarized beam propagation. The inability to predict instrument induced polarization or to define polarization performance expectations has far reaching implications for up and coming major observatories, such as the Daniel K. Inouye Solar Telescope (DKIST), that aim to take polarization measurements at unprecedented sensitivity and resolution.Here we present a method for modelling the wavelength dependent refractive index of an optic using Berreman calculus - a mathematical formalism that describes how an electromagnetic field propagates through a birefringent medium. From Berreman calculus, we can better predict the Mueller matrix, diattenuation, and retardance of an arbitrary thicknesses of amorphous many-layer coatings as well as stacks of birefringent crystals from laboratory measurements. This will allow for the wavelength dependent refractive index to be accurately determined and the polarization behavior to be derived for a given optic.

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.

Adipocyte property evaluation with photoacoustic spectrum analysis: a feasibility study on human tissues

NASA Astrophysics Data System (ADS)

Cao, Meng; Zhu, Yunhao; O'Rourke, Robert; Wang, Huaideng; Yuan, Jie; Cheng, Qian; Xu, Guan; Wang, Xueding; Carson, Paul

2017-03-01

Photoacoustic spectrum analysis (PASA) offers potential advantages in identifying optically absorbing microstructures in biological tissues. Working at high ultrasound frequency, PASA is capable of identifying the morphological features of cells based on their intrinsic optical absorption. Adipocyte size is correlated with metabolic disease risk in the form of diabetes mellitus, thus it can be adopted as a pathology predictor to evaluate the condition of obese patient, and can be helpful for assessing the patient response to bariatric surgery. In order to acquire adipocyte size, usually adipose tissue biopsy is performed and histopathology analysis is conducted. The whole procedure is not well tolerated by patients, and is also labor and cost intensive. An unmet need is to quantify and predict adipocyte size in a mild and more efficient way. This work aims at studying the feasibility to analyze the adipocyte size of human fat tissue using the method of PASA. PA measurements were performed at the optical wavelength of 1210 nm where lipid has strong optical absorption, enabling the study of adipocyte without need of staining. Both simulation and ex vivo experiments have been completed. Good correlation between the quantified photoacoustic spectral parameter slope and the average adipocyte size obtained by the gold-standard histology has been established. This initial study suggests the potential opportunity of applying PASA to future clinical management of obesity.

Optical communications beyond orbital angular momentum

NASA Astrophysics Data System (ADS)

Rosales-Guzmán, Carmelo; Trichili, Abderrahmen; Dudley, Angela; Ndagano, Bienvenu; Ben Salem, Amine; Zghal, Mourad; Forbes, Andrew

2016-09-01

Current optical communication technologies are predicted to face a bandwidth capacity limit in the near future. The nature of the limitation is fundamental rather than technological and is set by nonlinearities in optical fibers. One solution, suggested over 30 years ago, comprises the use of spatial modes of light as information carriers. Along this direction, light beams endowed with orbital angular momentum (OAM) have been demonstrated as potential information carriers in both, free space and fibres. However, recent studies suggest that purely OAM modes does not increase the bandwidth of optical communication systems. In fact, in all work to date, only the azimuthal component of transverse spatial modes has been used. Crucially, all transverse spatial modes require two degrees of freedom to be described; in the context of Laguerre-Gaussian (LGp`) beams these are azimuthal (l) and radial (p), the former responsible for OAM. Here, we demonstrate a technique where both degrees of freedom of LG modes are used as information carrier over free space. We transfer images encoded using 100 spatial modes in three wavelengths as our basis, and employ a spatial demultiplexing scheme that detects all 100 modes simultaneously. Our scheme is a hybrid of MIMO and SMM, and serves as a proof-of-principle demonstration. The cross-talk between the modes is small and independent of whether OAM modes are used or not.

Anticipating Their Future: Adolescent Values for the Future Predict Adult Behaviors

PubMed Central

Finlay, Andrea; Wray-Lake, Laura; Warren, Michael; Maggs, Jennifer L.

2014-01-01

Adolescent future values – beliefs about what will matter to them in the future – may shape their adult behavior. Utilizing a national longitudinal British sample, this study examined whether adolescent future values in six domains (i.e., family responsibility, full-time job, personal responsibility, autonomy, civic responsibility, and hedonistic privilege) predicted adult social roles, civic behaviors, and alcohol use. Future values positively predicted behaviors within the same domain; fewer cross-domain associations were evident. Civic responsibility positively predicted adult civic behaviors, but negatively predicted having children. Hedonistic privilege positively predicted adult alcohol use and negatively predicted civic behaviors. Results suggest that attention should be paid to how adolescents are thinking about their futures due to the associated links with long-term social and health behaviors. PMID:26279595

Methods of multi-conjugate adaptive optics for astronomy

NASA Astrophysics Data System (ADS)

Flicker, Ralf

2003-07-01

This work analyses several aspects of multi-conjugate adaptive optics (MCAO) for astronomy. The research ranges from fundamental and technical studies for present-day MCAO projects, to feasibility studies of high-order MCAO instruments for the extremely large telescopes (ELTs) of the future. The first part is an introductory exposition on atmospheric turbulence, adaptive optics (AO) and MCAO, establishing the framework within which the research was carried out The second part (papers I VI) commences with a fundamental design parameter study of MCAO systems, based upon a first-order performance estimation Monte Carlo simulation. It is investigated how the number and geometry of deformable mirrors and reference beacons, and the choice of wavefront reconstruction algorithm, affect system performance. Multi-conjugation introduces the possibility of optically canceling scintillation in part, at the expense of additional optics, by applying the phase correction in a certain sequence. The effects of scintillation when this sequence is not observed are investigated. As a link in characterizing anisoplanatism in conventional AO systems, images made with the AO instrument Hokupa'a on the Gemini-North Telescope were analysed with respect to the anisoplanatism signal. By model-fitting of simulated data, conclusions could be drawn about the vertical distribution of turbulence above the observatory site (Mauna Kea), and the significance to future AO and MCAO instruments with conjugated deformable mirrors is addressed. The problem of tilt anisoplanatism with MCAO systems relying on artificial reference beacons—laser guide stars (LGSs)—is analysed, and analytical models for predicting the effects of tilt anisoplanatism are devised. A method is presented for real-time retrieval of the tilt anisoplanatism point spread function (PSF), using control loop data. An independent PSF estimation of high accuracy is thus obtained which enables accurate PSF photometry and deconvolution. Lastly, a first-order performance estimation method is presented by which MCAO systems for ELTs may be studied efficiently, using sparse matrix techniques for wavefront reconstruction and a hybrid numerical/analytical simulation model. MCAO simulation results are presented for a wide range of telescope diameters up to 100 meters, and the effects of LGSs and a finite turbulence outer scale are investigated.

Converged photonic data storage and switch platform for exascale disaggregated data centers

NASA Astrophysics Data System (ADS)

Pitwon, R.; Wang, K.; Worrall, A.

2017-02-01

We report on a converged optically enabled Ethernet storage, switch and compute platform, which could support future disaggregated data center architectures. The platform includes optically enabled Ethernet switch controllers, an advanced electro-optical midplane and optically interchangeable generic end node devices. We demonstrate system level performance using optically enabled Ethernet disk drives and micro-servers across optical links of varied lengths.

The optical system of the proposed Chinese 12-m optical/infrared telescope

NASA Astrophysics Data System (ADS)

Su, Ding-qiang; Liang, Ming; Yuan, Xiangyan; Bai, Hua; Cui, Xiangqun

2017-08-01

The lack of a large-aperture optical/infrared telescope has seriously affected the development of astronomy in China. In 2016, the authors published their concept study and suggestions for a 12-m telescope optical system. This article presents the authors' further research and some new results. Considering that this telescope should be a general-purpose telescope for a wide range of scientific goals and could be used for frontier scientific research in the future, the authors studied and designed a variety of 12-m telescope optical systems for comparison and final decision-making. In general, we still adopt our previous configuration, but the Nasmyth and prime-focus corrector systems have been greatly improved. In this article, the adaptive optics is given special attention. Ground-layer adaptive optics (GLAO) is adopted. It has a 14-arcmin field of view. The secondary mirror is used as the adaptive optical deformable mirror. Obviously, not all the optical systems in this telescope configuration will be used or constructed at the same stage. Some will be for the future and some are meant for research rather than for construction.

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.

Optical Information Processing for Aerospace Applications 2

NASA Technical Reports Server (NTRS)

Stermer, R. L. (Compiler)

1984-01-01

Current research in optical processing, and determination of its role in future aerospace systems was reviewed. It is shown that optical processing offers significant potential for aircraft and spacecraft control, pattern recognition, and robotics. It is demonstrated that the development of optical devices and components can be implemented in practical aerospace configurations.

Contributions to workload of rotational optical transformations

NASA Technical Reports Server (NTRS)

Atkinson, R. P.; Harrington, T. L.

1985-01-01

An investigation of visuomotor adaptation to optical rotation and optical inversion was conducted. Experiment 1 examined the visuomotor adaptability of subjects to an optically rotating visual world with a univariate repeated measures design. Experiment 1A tested one major prediction of a model of adaptation put forth by Welch who predicted that the aversive drive state that triggers adaptation would be habituated to fairly rapidly. Experiment 2 was conducted to investigate the role of motor activity in adaptation to optical rotation. Specifically, this experiment contrasted the reafference hypothesis and the proprioceptive change hypothesis. Experiment 3 examined the role of cognition, error-corrective feedback, and proprioceptive and/or reafferent feedback in visuomotor adaptation to optical inversion. Implications for research and implications for practice were suggested for all experiments.

Sensitivity of corneal biomechanical and optical behavior to material parameters using design of experiments method.

PubMed

Xu, Mengchen; Lerner, Amy L; Funkenbusch, Paul D; Richhariya, Ashutosh; Yoon, Geunyoung

2018-02-01

The optical performance of the human cornea under intraocular pressure (IOP) is the result of complex material properties and their interactions. The measurement of the numerous material parameters that define this material behavior may be key in the refinement of patient-specific models. The goal of this study was to investigate the relative contribution of these parameters to the biomechanical and optical responses of human cornea predicted by a widely accepted anisotropic hyperelastic finite element model, with regional variations in the alignment of fibers. Design of experiments methods were used to quantify the relative importance of material properties including matrix stiffness, fiber stiffness, fiber nonlinearity and fiber dispersion under physiological IOP. Our sensitivity results showed that corneal apical displacement was influenced nearly evenly by matrix stiffness, fiber stiffness and nonlinearity. However, the variations in corneal optical aberrations (refractive power and spherical aberration) were primarily dependent on the value of the matrix stiffness. The optical aberrations predicted by variations in this material parameter were sufficiently large to predict clinically important changes in retinal image quality. Therefore, well-characterized individual variations in matrix stiffness could be critical in cornea modeling in order to reliably predict optical behavior under different IOPs or after corneal surgery.

A theoretical review on electronic, magnetic and optical properties of silicene.

PubMed

Chowdhury, Suman; Jana, Debnarayan

2016-12-01

Inspired by the success of graphene, various two dimensional (2D) structures in free standing (FS) (hypothetical) form and on different substrates have been proposed recently. Silicene, a silicon counterpart of graphene, is predicted to possess massless Dirac fermions and to exhibit an experimentally accessible quantum spin Hall effect. Since the effective spin-orbit interaction is quite significant compared to graphene, buckling in silicene opens a gap of 1.55 meV at the Dirac point. This band gap can be further tailored by applying in plane stress, an external electric field, chemical functionalization and defects. In this topical theoretical review, we would like to explore the electronic, magnetic and optical properties, including Raman spectroscopy of various important derivatives of monolayer and bilayer silicene (BLS) with different adatoms (doping). The magnetic properties can be tailored by chemical functionalization, such as hydrogenation and introducing vacancy into the pristine planar silicene. Apart from some universal features of optical absorption present in all these 2D materials, the study on reflectivity modulation with doping (Al and P) concentration in silicene has indicated the emergence of some strong peaks having the robust characteristic of a doped reflective surface for both polarizations of the electromagnetic (EM) field. Besides this, attempts will be made to understand the electronic properties of silicene from some simple tight-binding Hamiltonian. We also point out the importance of shape dependence and optical anisotropy properties in silicene nanodisks and establish that a zigzag trigonal possesses the maximum magnetic moment. We also suggest future directions to be explored to make the synthesis of silicene and its various derivatives viable for verification of theoretical predictions. Although this is a fairly new route, the results obtained so far from experimental and theoretical studies in understanding silicene have shown enough significant promising features to open a new direction in the silicon industry, silicon based nano-structures in spintronics and in opto-electronic devices.

New trends in space x-ray optics

NASA Astrophysics Data System (ADS)

Hudec, R.; Maršíková, V.; Pína, L.; Inneman, A.; Skulinová, M.

2017-11-01

The X-ray optics is a key element of various X-ray telescopes, X-ray microscopes, as well as other X-ray imaging instruments. The grazing incidence X-ray lenses represent the important class of X-ray optics. Most of grazing incidence (reflective) X-ray imaging systems used in astronomy but also in other (laboratory) applications are based on the Wolter 1 (or modified) arrangement. But there are also other designs and configurations proposed, used and considered for future applications both in space and in laboratory. The Kirkpatrick-Baez (K-B) lenses as well as various types of Lobster-Eye optics and MCP/Micropore optics serve as an example. Analogously to Wolter lenses, the X-rays are mostly reflected twice in these systems to create focal images. Various future projects in X-ray astronomy and astrophysics will require large segments with multiple thin shells or foils. The large Kirkpatrick-Baez modules, as well as the large Lobster-Eye X-ray telescope modules in Schmidt arrangement may serve as examples. All these space projects will require high quality and light segmented shells (bent or flat foils) with high X-ray reflectivity and excellent mechanical stability. The Multi Foil Optics (MFO) approach represent a promising alternative for both LE and K-B X-ray optical modules. Several types of reflecting substrates may be considered for these applications, with emphasis on thin float glass sheets and, more recently, high quality silicon wafers. This confirms the importance of non- Wolter X-ray optics designs for the future. Future large space X-ray telescopes (such as IXO) require precise and light-weight X-ray optics based on numerous thin reflecting shells. Novel approaches and advanced technologies are to be exploited and developed. In this contribution, we refer on results of tested X-ray mirror shells produced by glass thermal forming (GTF) and by shaping Si wafers. Both glass foils and Si wafers are commercially available, have excellent surface microroughness of a few 0.1 nm, and low weight (the volume density is 2.5 g cm-3 for glass and 2.3 g cm-3 for Si). Technologies are needed to be exploited; how to shape these substrates to achieve the required precise Xray optics geometries without degradations of the fine surface microroughness. Although glass and recently silicon wafers are considered to represent most promising materials for future advanced large aperture space Xray telescopes, there also exist other alternative materials worth further study such as amorphous metals and glassy carbon [1]. In order to achieve sub-arsec angular resolutions, principles of active optics have to be adopted.

Potential of OFDM for next generation optical access

NASA Astrophysics Data System (ADS)

Fritzsche, Daniel; Weis, Erik; Breuer, Dirk

2011-01-01

This paper shows the requirements for next generation optical access (NGOA) networks and analyzes the potential of OFDM (orthogonal frequency division multiplexing) for the use in such network scenarios. First, we show the motivation for NGOA systems based on the future requirements on FTTH access systems and list the advantages of OFDM in such scenarios. In the next part, the basics of OFDM and different methods to generate and detect optical OFDM signals are explained and analyzed. At the transmitter side the options include intensity modulation and the more advanced field modulation of the optical OFDM signal. At the receiver there is the choice between direct detection and coherent detection. As the result of this discussion we show our vision of the future use of OFDM in optical access networks.

Applications for Freeforms Optics at NASA

NASA Technical Reports Server (NTRS)

West, Garrett J.; Howard, Joseph M.

2017-01-01

Review freeform optic applications as NASA. Describe design study results showing benefits of freeform optics to the instrument size, image quality, and field of view. Review areas of study and improvements needed to freeform manufacturing for future applications.

Recent flight-test results of optical airdata techniques

NASA Technical Reports Server (NTRS)

Bogue, Rodney K.

1993-01-01

Optical techniques for measuring airdata parameters were demonstrated with promising results on high performance fighter aircraft. These systems can measure the airspeed vector, and some are not as dependent on special in-flight calibration processes as current systems. Optical concepts for measuring freestream static temperature and density are feasible for in-flight applications. The best feature of these concepts is that the air data measurements are obtained nonintrusively, and for the most part well into the freestream region of the flow field about the aircraft. Current requirements for measuring air data at high angle of attack, and future need to measure the same information at hypersonic flight conditions place strains on existing techniques. Optical technology advances show outstanding potential for application in future programs and promise to make common use of optical concepts a reality. Results from several flight-test programs are summarized, and the technology advances required to make optical airdata techniques practical are identified.

Self-Organization of Metal Nanoparticles in Light: Electrodynamics-Molecular Dynamics Simulations and Optical Binding Experiments.

PubMed

McCormack, Patrick; Han, Fei; Yan, Zijie

2018-02-01

Light-driven self-organization of metal nanoparticles (NPs) can lead to unique optical matter systems, yet simulation of such self-organization (i.e., optical binding) is a complex computational problem that increases nonlinearly with system size. Here we show that a combined electrodynamics-molecular dynamics simulation technique can simulate the trajectories and predict stable configurations of silver NPs in optical fields. The simulated dynamic equilibrium of a two-NP system matches the probability density of oscillations for two optically bound NPs obtained experimentally. The predicted stable configurations for up to eight NPs are further compared to experimental observations of silver NP clusters formed by optical binding in a Bessel beam. All configurations are confirmed to form in real systems, including pentagonal clusters with five-fold symmetry. Our combined simulations and experiments have revealed a diverse optical matter system formed by anisotropic optical binding interactions, providing a new strategy to discover artificial materials.

Can Probability Maps of Swept-Source Optical Coherence Tomography Predict Visual Field Changes in Preperimetric Glaucoma?

PubMed

Lee, Won June; Kim, Young Kook; Jeoung, Jin Wook; Park, Ki Ho

2017-12-01

To determine the usefulness of swept-source optical coherence tomography (SS-OCT) probability maps in detecting locations with significant reduction in visual field (VF) sensitivity or predicting future VF changes, in patients with classically defined preperimetric glaucoma (PPG). Of 43 PPG patients, 43 eyes were followed-up on every 6 months for at least 2 years were analyzed in this longitudinal study. The patients underwent wide-field SS-OCT scanning and standard automated perimetry (SAP) at the time of enrollment. With this wide-scan protocol, probability maps originating from the corresponding thickness map and overlapped with SAP VF test points could be generated. We evaluated the vulnerable VF points with SS-OCT probability maps as well as the prevalence of locations with significant VF reduction or subsequent VF changes observed in the corresponding damaged areas of the probability maps. The vulnerable VF points were shown in superior and inferior arcuate patterns near the central fixation. In 19 of 43 PPG eyes (44.2%), significant reduction in baseline VF was detected within the areas of structural change on the SS-OCT probability maps. In 16 of 43 PPG eyes (37.2%), subsequent VF changes within the areas of SS-OCT probability map change were observed over the course of the follow-up. Structural changes on SS-OCT probability maps could detect or predict VF changes using SAP, in a considerable number of PPG eyes. Careful comparison of probability maps with SAP results could be useful in diagnosing and monitoring PPG patients in the clinical setting.

Atmospheric Signatures and Effects of Space-based Relativistic Electron Beam Injection

NASA Astrophysics Data System (ADS)

Marshall, R. A.; Sanchez, E. R.; Kero, A.; Turunen, E. S.; Marsh, D. R.

2017-12-01

Future relativistic electron beam injection experiments have the potential to provide groundbreaking insights into the physics of wave-particle interactions and beam-neutral interactions, relevant to space physics and to fundamental plasma physics. However, these experiments are only useful if their signatures can be detected. In this work, we use a physics-based forward modeling framework to investigate the observable signatures of a relativistic beam interacting with the upper atmosphere. The modeling framework is based around the Electron Precipitation Monte Carlo (EPMC) model, used to simulate electron precipitation in the upper atmosphere. That model is coupled to physics-based models of i) optical emission production; ii) bremsstrahlung photon production and propagation; iii) D-region ion chemistry; and iv) VLF wave propagation in the Earth-ionosphere waveguide. Using these modeling tools, we predict the optical, X-ray, chemical, radar, and VLF signatures of a realistic beam injection, based on recent space-based accelerator designs. In particular, we inject a beam pulse of 10 mA for a duration of 500 μs at an energy of 1 MeV, providing a total pulse energy of 5 J. We further investigate variations in these parameters, in particular the total energy and the electron energy. Our modeling shows that for this 5 J pulse injection at 1 MeV electron energy, the optical signal is easily detectable from the ground in common emission bands, but the X-ray signal is likely too weak to be seen from either balloons or LEO orbiting spacecraft. We further predict the optical signal-to-noise ratio that would be expected in different optical systems. Chemical signatures such as changes to NOx and HOx concentrations are too short-lived to be detectable; however our modeling provides a valuable estimate of the total chemical response. Electron density perturbations should be easily measurable from ground-based high-power radars and via VLF subionospheric remote sensing. However, the VLF diagnostic is complicated by the geometry of the problem, in that the perturbation in the upper atmosphere is much smaller than the VLF wavelength, so wide-angle scattering needs to be taken into account.

Hierarchical Models for Type Ia Supernova Light Curves in the Optical and Near Infrared

NASA Astrophysics Data System (ADS)

Mandel, Kaisey; Narayan, G.; Kirshner, R. P.

2011-01-01

I have constructed a comprehensive statistical model for Type Ia supernova optical and near infrared light curves. Since the near infrared light curves are excellent standard candles and are less sensitive to dust extinction and reddening, the combination of near infrared and optical data better constrains the host galaxy extinction and improves the precision of distance predictions to SN Ia. A hierarchical probabilistic model coherently accounts for multiple random and uncertain effects, including photometric error, intrinsic supernova light curve variations and correlations across phase and wavelength, dust extinction and reddening, peculiar velocity dispersion and distances. An improved BayeSN MCMC code is implemented for computing probabilistic inferences for individual supernovae and the SN Ia and host galaxy dust populations. I use this hierarchical model to analyze nearby Type Ia supernovae with optical and near infared data from the PAIRITEL, CfA3, and CSP samples and the literature. Using cross-validation to test the robustness of the model predictions, I find that the rms Hubble diagram scatter of predicted distance moduli is 0.11 mag for SN with optical and near infrared data versus 0.15 mag for SN with only optical data. Accounting for the dispersion expected from random peculiar velocities, the rms intrinsic prediction error is 0.08-0.10 mag for SN with both optical and near infrared light curves. I discuss results for the inferred intrinsic correlation structures of the optical-NIR SN Ia light curves and the host galaxy dust distribution captured by the hierarchical model. The continued observation and analysis of Type Ia SN in the optical and near infrared is important for improving their utility as precise and accurate cosmological distance indicators.

The applicability of physical optics in the millimetre and sub-millimetre spectral region. Part I: The ray tracing with diffraction on facets method

NASA Astrophysics Data System (ADS)

Baran, A. J.; Hesse, Evelyn; Sourdeval, Odran

2017-03-01

Future satellite missions, from 2022 onwards, will obtain near-global measurements of cirrus at microwave and sub-millimetre frequencies. To realise the potential of these observations, fast and accurate light-scattering methods are required to calculate scattered millimetre and sub-millimetre intensities from complex ice crystals. Here, the applicability of the ray tracing with diffraction on facets method (RTDF) in predicting the bulk scalar optical properties and phase functions of randomly oriented hexagonal ice columns and hexagonal ice aggregates at millimetre frequencies is investigated. The applicability of RTDF is shown to be acceptable down to size parameters of about 18, between the frequencies of 243 and 874 GHz. It is demonstrated that RTDF is generally well within about 10% of T-matrix solutions obtained for the scalar optical properties assuming hexagonal ice columns. Moreover, on replacing electromagnetic scalar optical property solutions obtained for the hexagonal ice aggregate with the RTDF counterparts at size parameter values of about 18 or greater, the bulk scalar optical properties can be calculated to generally well within ±5% of an electromagnetic-based database. The RTDF-derived bulk scalar optical properties result in brightness temperature errors to generally within about ±4 K at 874 GHz. Differing microphysics assumptions can easily exceed such errors. Similar findings are found for the bulk scattering phase functions. This finding is owing to the scattering solutions being dominated by the processes of diffraction and reflection, both being well described by RTDF. The impact of centimetre-sized complex ice crystals on interpreting cirrus polarisation measurements at sub-millimetre frequencies is discussed.

Origin and Future of Plasmonic Optical Tweezers

PubMed Central

Huang, Jer-Shing; Yang, Ya-Tang

2015-01-01

Plasmonic optical tweezers can overcome the diffraction limits of conventional optical tweezers and enable the trapping of nanoscale objects. Extension of the trapping and manipulation of nanoscale objects with nanometer position precision opens up unprecedented opportunities for applications in the fields of biology, chemistry and statistical and atomic physics. Potential applications include direct molecular manipulation, lab-on-a-chip applications for viruses and vesicles and the study of nanoscale transport. This paper reviews the recent research progress and development bottlenecks and provides an overview of possible future directions in this field. PMID:28347051

Origin and Future of Plasmonic Optical Tweezers.

PubMed

Huang, Jer-Shing; Yang, Ya-Tang

2015-06-12

Plasmonic optical tweezers can overcome the diffraction limits of conventional optical tweezers and enable the trapping of nanoscale objects. Extension of the trapping and manipulation of nanoscale objects with nanometer position precision opens up unprecedented opportunities for applications in the fields of biology, chemistry and statistical and atomic physics. Potential applications include direct molecular manipulation, lab-on-a-chip applications for viruses and vesicles and the study of nanoscale transport. This paper reviews the recent research progress and development bottlenecks and provides an overview of possible future directions in this field.

Optical ground station site diversity for Deep Space Optical Communications the Mars Telecom Orbiter optical link

NASA Technical Reports Server (NTRS)

Wilson, K.; Parvin, B.; Fugate, R.; Kervin, P.; Zingales, S.

2003-01-01

Future NASA deep space missions will fly advanced high resolution imaging instruments that will require high bandwidth links to return the huge data volumes generated by these instruments. Optical communications is a key technology for returning these large data volumes from deep space probes. Yet to cost effectively realize the high bandwidth potential of the optical link will require deployment of ground receivers in diverse locations to provide high link availability. A recent analysis of GOES weather satellite data showed that a network of ground stations located in Hawaii and the Southwest continental US can provide an average of 90% availability for the deep space optical link. JPL and AFRL are exploring the use of large telescopes in Hawaii, California, and Albuquerque to support the Mars Telesat laser communications demonstration. Designed to demonstrate multi-Mbps communications from Mars, the mission will investigate key operational strategies of future deep space optical communications network.

A novel optical fibre doped with the nano-material as InP

NASA Astrophysics Data System (ADS)

Chen, Xi; Lee, Ly Guat; Zhang, Ru

2007-11-01

As the key of these optical devices which are widely used in the communication system, high nonlinear optical fibre will play an important role in the future optical fibre communication. With recent growth of nano-technology, researchers are hoping to obtain some kinds of optical fibre by combining the optical fibre with the nanotechnology. According to this current situation, the optical fibre doped with nano-material as InP (indium phosphide) is manufactured by using the MCVD (modified chemical vapor deposition) technology after our comprehensive consideration of many relative factors. Proved by experiments, this novel optical fibre has an excellent waveguide characteristic. After a consideration of the model of this novel optical fibre, its propagation constant β has been simulated by using the FEM (finite element method), and the graphs of presentation of magnetic field of the core are also obtained. In accordance with the results, the effective refractive index n eff = 1.401 has be calculated. Both the calculated result and the simulated graphs are matching well with the test, and this result is a step-stone bridge for future research of nonlinear parameter on this novel optical fiber.

The Space Optical Clock project: status and perspectives

NASA Astrophysics Data System (ADS)

Schiller, Stephan; Tino, Guglielmo M.; Sterr, Uwe; Lemonde, Pierre; Görlitz, Axel; Salomon, Christophe

The Space Optical Clocks project aims at operating lattice clocks on the ISS for tests of funda-mental physics and for providing high-accuracy comparisons of future terrestrial optical clocks. A pre-phase-A study (2007-10), funded partially by ESA and DLR, includes the implementa-tion of several optical lattice clock systems using Strontium and Ytterbium as atomic systems and their characterization. Subcomponents of clock demonstrators with the added specification of transportability and using techniques that are suitable for later space use, such as all-solid-state lasers, low power consumption, and compact dimensions, have been developed and are being validated. The talk will give a brief overview over the achieved results and outline future developments.

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.

Random fluctuations of optical signal path delay in the atmosphere

NASA Astrophysics Data System (ADS)

Kral, L.; Prochazka, I.; Hamal, K.

2006-09-01

Atmospheric turbulence induces random delay fluctuations to any optical signal transmitted through the air. These fluctuations can influence for example the measurement precision of laser rangefinders. We have found an appropriate theoretical model based on geometrical optics that allows us to predict the amplitude of the random delay fluctuations for different observing conditions. We have successfully proved the applicability of this model by a series of experiments, directly determining the amplitude of the turbulence-induced pulse delay fluctuations by analysis of a high precision laser ranging data. Moreover, we have also shown that a standard theoretical approach based on diffractive propagation of light through inhomogeneous media and implemented using the GLAD software is not suitable for modeling of the optical signal delay fluctuations caused by the atmosphere. These models based on diffractive propagation predict the turbulence-induced optical path length fluctuations of the order of micrometers, whereas the fluctuations predicted by the geometrical optics model (in agreement with our experimental data) are generally larger by two orders of magnitude, i.e. in the submillimeter range. The reason of this discrepancy is a subject to discussion.

X-ray free-electron laser studies of dense plasmas

NASA Astrophysics Data System (ADS)

Vinko, Sam M.

2015-10-01

> The high peak brightness of X-ray free-electron lasers (FELs), coupled with X-ray optics enabling the focusing of pulses down to sub-micron spot sizes, provides an attractive route to generating high energy-density systems on femtosecond time scales, via the isochoric heating of solid samples. Once created, the fundamental properties of these plasmas can be studied with unprecedented accuracy and control, providing essential experimental data needed to test and benchmark commonly used theoretical models and assumptions in the study of matter in extreme conditions, as well as to develop new predictive capabilities. Current advances in isochoric heating and spectroscopic plasma studies on X-ray FELs are reviewed and future research directions and opportunities discussed.

Channeling of multikilojoule high-intensity laser beams in an inhomogeneous plasma

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

Ivancic, S.; Haberberger, D.; Habara, H.

Channeling experiments were performed that demonstrate the transport of high-intensity (>10¹⁸ W/cm²), multikilojoule laser light through a millimeter-sized, inhomogeneous (~300-μm density scale length) laser produced plasma up to overcritical density, which is an important step forward for the fast-ignition concept. The background plasma density and the density depression inside the channel were characterized with a novel optical probe system. The channel progression velocity was measured, which agrees well with theoretical predictions based on large scale particle-in-cell simulations, confirming scaling laws for the required channeling laser energy and laser pulse duration, which are important parameters for future integrated fast-ignition channeling experiments.

Optomechanical Design and Analysis Considerations on the Lunar Orbiter Laser Altimeter

NASA Technical Reports Server (NTRS)

Schmidt. Stephen; Mamakos, William; Matzinger, Elizabeth; Wall, Sheila

2007-01-01

This paper presents the mechanical design and analysis work completed on the Lunar Orbiter Laser Altimeter (LOLA). LOLA is one of six instruments on the Lunar Reconnaissance Orbiter (LRO), scheduled to launch in 2008. LOLA's main objective is to produce a high-resolution global lunar topographic model to aid in safe landings and enhance surface mobility in future exploration missions. LOLA will also look for evidence of ice water in the permanently shadowed regions around the lunar poles. Beryllium was chosen as the primary material for the LOLA Optical Transmitter Assembly to take advantage of the material's low mass density for light weight optical instrument design and for CTE matching of the refractive optical components. In addition, the thermal conductivity and specific heat of beryllium minimizes thermal gradients and thermal excursions. Special consideration must be made for the planning and preparation to fabricate beryllium components, as well as the preparation and cleaning of the components for gold plating. Assembly challenges include handling, precision cleaning and integration and testing. Structural analysis considerations include following General Environmental Verification Specification (GEVS) guidelines for GSFC payloads. The GEVS random environment for LOLA has an acceptance level of 10.0 Grms, which was analyzed for higher frequency transients. The low frequency transients were analyzed using a Mass Acceleration Curve to obtain an equivalent static loading. In addition, Structural-Thermal-Optical analysis, commonly referred to as STOP analysis, was completed to predict optical performance under the instrument's operational thermal environment. This included stress and distortion analysis on the receiver telescope lens.

Overview of Fiber-Optical Sensors

NASA Technical Reports Server (NTRS)

Depaula, Ramon P.; Moore, Emery L.

1987-01-01

Design, development, and sensitivity of sensors using fiber optics reviewed. State-of-the-art and probable future developments of sensors using fiber optics described in report including references to work in field. Serves to update previously published surveys. Systems incorporating fiber-optic sensors used in medical diagnosis, navigation, robotics, sonar, power industry, and industrial controls.

Everything You Always Wanted to Know about Fiber Optics but Were Afraid to Ask...

ERIC Educational Resources Information Center

Bunch, Robert M.

1993-01-01

Explains light-wave communication and optical fibers. The impact of fiber optics on communication is discussed; uses of fiber optic technology in elementary, secondary, and higher education are described; and possible futures of light-wave communication are considered, including Integrated Services Digital Networks and the National Research and…

HgCdTe APDs for time-resolved space applications

NASA Astrophysics Data System (ADS)

Rothman, J.; Lasfargues, G.; Delacourt, B.; Dumas, A.; Gibert, F.; Bardoux, A.; Boutillier, M.

2017-12-01

The use of HgCdTe avalanche photodiodes (APDs) for resolving the temporal variation of faint light level signals is analyzed. The analysis is based on the performance characteristics such as the gain, the response time, and dark currents in the APDs, measured as a function of operating temperature and Cd composition, and on recently developed detector demonstrator modules. The choice of Cd composition in the APDs is strongly dependent on the application needs in terms of electrical bandwidth and signal-to-noise ratio. A performance model has been developed and used to predict the performance of the future detector modules for different applications such as high bandwidth and/or deep space free space optical telecommunications and lidar, associated with sensitivities down to single photon level at low operating temperature and close to single-photon operation at bandwidth of 10 GHz at room temperature. The predictions are corroborated by the results obtained on detector modules that have been developed and used in lidar and deep space optical communications. In a first lidar prototype, integrating a 200 µm APD, we obtained a maximum sensitivity of 25 fW/√Hz at T = 190 K operating temperature. The detector has been used for differential absorption lidar estimations of the absorption due to presence of CO2 in the atmosphere. A random error of 3-10% was obtained for the estimation of the optical thickness at a distance of 100-3000 m, for a range resolution of 100 m and using and averaging time of 4 s. The pursuit of this development is pending on the space qualification of the technology. Results from first proton and irradiation tests are reported that shows on a close to constant performance during and after the irradiation and endurance tests.

Roadmap on quantum optical systems

NASA Astrophysics Data System (ADS)

Dumke, Rainer; Lu, Zehuang; Close, John; Robins, Nick; Weis, Antoine; Mukherjee, Manas; Birkl, Gerhard; Hufnagel, Christoph; Amico, Luigi; Boshier, Malcolm G.; Dieckmann, Kai; Li, Wenhui; Killian, Thomas C.

2016-09-01

This roadmap bundles fast developing topics in experimental optical quantum sciences, addressing current challenges as well as potential advances in future research. We have focused on three main areas: quantum assisted high precision measurements, quantum information/simulation, and quantum gases. Quantum assisted high precision measurements are discussed in the first three sections, which review optical clocks, atom interferometry, and optical magnetometry. These fields are already successfully utilized in various applied areas. We will discuss approaches to extend this impact even further. In the quantum information/simulation section, we start with the traditionally successful employed systems based on neutral atoms and ions. In addition the marvelous demonstrations of systems suitable for quantum information is not progressing, unsolved challenges remain and will be discussed. We will also review, as an alternative approach, the utilization of hybrid quantum systems based on superconducting quantum devices and ultracold atoms. Novel developments in atomtronics promise unique access in exploring solid-state systems with ultracold gases and are investigated in depth. The sections discussing the continuously fast-developing quantum gases include a review on dipolar heteronuclear diatomic gases, Rydberg gases, and ultracold plasma. Overall, we have accomplished a roadmap of selected areas undergoing rapid progress in quantum optics, highlighting current advances and future challenges. These exciting developments and vast advances will shape the field of quantum optics in the future.

Using Remote Sensing Observations and Empirical-Statistical Methods to Understand the Present State and Predictable Future Changes in the State of Permafrost Distribution in North-Western Himalayas

NASA Astrophysics Data System (ADS)

Baral, P.; Haq, M. A.; Mangan, P.

2017-12-01

The impacts of climate change on extent of permafrost degradation in the Himalayas and its effect upon the carbon cycle and ecosystem changes are not well understood due to lack of historical ground-based observations. We have used high resolution optical and satellite radar observations and applied empirical-statistical methods for the estimation of spatial and altitudinal limits of permafrost distribution in North-Western Himalayas. Visual interpretations of morphological characteristics using high resolution optical images have been used for mapping, identification and classification of distinctive geomorphological landforms. Subsequently, we have created a detail inventory of different types of rock glaciers and studied the contribution of topo climatic factors in their occurrence and distribution through Logistic Regression modelling. This model establishes the relationship between presence of permafrost and topo-climatic factors like Mean Annual Air Temperature (MAAT), Potential Incoming Solar Radiation (PISR), altitude, aspect and slope. This relationship has been used to estimate the distributed probability of permafrost occurrence, within a GIS environment. The ability of the model to predict permafrost occurrence has been tested using locations of mapped rock glaciers and the area under the Receiver Operating Characteristic (ROC) curve. Additionally, interferometric properties of Sentinel and ALOS PALSAR datasets are used for the identification and assessment of rock glacier activity in the region.

Organic Materials For Optical Switching

NASA Technical Reports Server (NTRS)

Cardelino, Beatriz H.

1993-01-01

Equations predict properties of candidate materials. Report presents results of theoretical study of nonlinear optical properties of organic materials. Such materials used in optical switching devices for computers and telecommunications, replacing electronic switches. Optical switching potentially offers extremely high information throughout in compact hardware.

Monte Carlo modeling of spatial coherence: free-space diffraction

PubMed Central

Fischer, David G.; Prahl, Scott A.; Duncan, Donald D.

2008-01-01

We present a Monte Carlo method for propagating partially coherent fields through complex deterministic optical systems. A Gaussian copula is used to synthesize a random source with an arbitrary spatial coherence function. Physical optics and Monte Carlo predictions of the first- and second-order statistics of the field are shown for coherent and partially coherent sources for free-space propagation, imaging using a binary Fresnel zone plate, and propagation through a limiting aperture. Excellent agreement between the physical optics and Monte Carlo predictions is demonstrated in all cases. Convergence criteria are presented for judging the quality of the Monte Carlo predictions. PMID:18830335

Comparing deflection measurements of a magnetically steerable catheter using optical imaging and MRI

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

Lillaney, Prasheel, E-mail: Prasheel.Lillaney@ucsf.edu; Caton, Curtis; Martin, Alastair J.

2014-02-15

Purpose: Magnetic resonance imaging (MRI) is an emerging modality for interventional radiology, giving clinicians another tool for minimally invasive image-guided interventional procedures. Difficulties associated with endovascular catheter navigation using MRI guidance led to the development of a magnetically steerable catheter. The focus of this study was to mechanically characterize deflections of two different prototypes of the magnetically steerable catheterin vitro to better understand their efficacy. Methods: A mathematical model for deflection of the magnetically steerable catheter is formulated based on the principle that at equilibrium the mechanical and magnetic torques are equal to each other. Furthermore, two different image basedmore » methods for empirically measuring the catheter deflection angle are presented. The first, referred to as the absolute tip method, measures the angle of the line that is tangential to the catheter tip. The second, referred to the base to tip method, is an approximation that is used when it is not possible to measure the angle of the tangent line. Optical images of the catheter deflection are analyzed using the absolute tip method to quantitatively validate the predicted deflections from the mathematical model. Optical images of the catheter deflection are also analyzed using the base to tip method to quantitatively determine the differences between the absolute tip and base to tip methods. Finally, the optical images are compared to MR images using the base to tip method to determine the accuracy of measuring the catheter deflection using MR. Results: The optical catheter deflection angles measured for both catheter prototypes using the absolute tip method fit very well to the mathematical model (R{sup 2} = 0.91 and 0.86 for each prototype, respectively). It was found that the angles measured using the base to tip method were consistently smaller than those measured using the absolute tip method. The deflection angles measured using optical data did not demonstrate a significant difference from the angles measured using MR image data when compared using the base to tip method. Conclusions: This study validates the theoretical description of the magnetically steerable catheter, while also giving insight into different methods and modalities for measuring the deflection angles of the prototype catheters. These results can be used to mechanically model future iterations of the design. Quantifying the difference between the different methods for measuring catheter deflection will be important when making deflection measurements in future studies. Finally, MR images can be used to reliably measure deflection angles since there is no significant difference between the MR and optical measurements.« less

Multi-Gigabit Free-Space Optical Data Communication and Network System

DTIC Science & Technology

2016-04-01

IR), Ultraviolet ( UV ), Laser Transceiver, Adaptive Beam Tracking, Electronic Attack (EA), Cyber Attack, Multipoint-to-Multipoint Network, Adaptive...FileName.pptx Free Space Optical Datalink Timeline Phase 1 Point-to-point demonstration 2012 Future Adaptive optic & Quantum Cascade Laser

Prediction performance of reservoir computing systems based on a diode-pumped erbium-doped microchip laser subject to optical feedback.

PubMed

Nguimdo, Romain Modeste; Lacot, Eric; Jacquin, Olivier; Hugon, Olivier; Van der Sande, Guy; Guillet de Chatellus, Hugues

2017-02-01

Reservoir computing (RC) systems are computational tools for information processing that can be fully implemented in optics. Here, we experimentally and numerically show that an optically pumped laser subject to optical delayed feedback can yield similar results to those obtained for electrically pumped lasers. Unlike with previous implementations, the input data are injected at a time interval that is much larger than the time-delay feedback. These data are directly coupled to the feedback light beam. Our results illustrate possible new avenues for RC implementations for prediction tasks.

Dynamic properties of the adaptive optics system depending on the temporary transformations of mirror control voltages

NASA Astrophysics Data System (ADS)

Lavrinov, V. V.; Lavrinova, L. N.

2017-11-01

The statistically optimal control algorithm for the correcting mirror is formed by constructing a prediction of distortions of the optical signal and improves the time resolution of the adaptive optics system. The prediction of distortions is based on an analysis of the dynamics of changes in the optical inhomogeneities of the turbulent atmosphere or the evolution of phase fluctuations at the input aperture of the adaptive system. Dynamic properties of the system are manifested during the temporary transformation of the stresses controlling the mirror and are determined by the dynamic characteristics of the flexible mirror.

III-V Semiconductor Optical Micro-Ring Resonators

NASA Astrophysics Data System (ADS)

Grover, Rohit; Absil, Philippe P.; Ibrahim, Tarek A.; Ho, Ping-Tong

2004-05-01

We describe the theory of optical ring resonators, and our work on GaAs-AlGaAs and GaInAsP-InP optical micro-ring resonators. These devices are promising building blocks for future all-optical signal processing and photonic logic circuits. Their versatility allows the fabrication of ultra-compact multiplexers/demultiplexers, optical channel dropping filters, lasers, amplifiers, and logic gates (to name a few), which will enable large-scale monolithic integration for optics.

Excitons in atomically thin 2D semiconductors and their applications

NASA Astrophysics Data System (ADS)

Xiao, Jun; Zhao, Mervin; Wang, Yuan; Zhang, Xiang

2017-06-01

The research on emerging layered two-dimensional (2D) semiconductors, such as molybdenum disulfide (MoS2), reveals unique optical properties generating significant interest. Experimentally, these materials were observed to host extremely strong light-matter interactions as a result of the enhanced excitonic effect in two dimensions. Thus, understanding and manipulating the excitons are crucial to unlocking the potential of 2D materials for future photonic and optoelectronic devices. In this review, we unravel the physical origin of the strong excitonic effect and unique optical selection rules in 2D semiconductors. In addition, control of these excitons by optical, electrical, as well as mechanical means is examined. Finally, the resultant devices such as excitonic light emitting diodes, lasers, optical modulators, and coupling in an optical cavity are overviewed, demonstrating how excitons can shape future 2D optoelectronics.

Determining degree of optic nerve edema from color fundus photography

NASA Astrophysics Data System (ADS)

Agne, Jason; Wang, Jui-Kai; Kardon, Randy H.; Garvin, Mona K.

2015-03-01

Swelling of the optic nerve head (ONH) is subjectively assessed by clinicians using the Frisén scale. It is believed that a direct measurement of the ONH volume would serve as a better representation of the swelling. However, a direct measurement requires optic nerve imaging with spectral domain optical coherence tomography (SD-OCT) and 3D segmentation of the resulting images, which is not always available during clinical evaluation. Furthermore, telemedical imaging of the eye at remote locations is more feasible with non-mydriatic fundus cameras which are less costly than OCT imagers. Therefore, there is a critical need to develop a more quantitative analysis of optic nerve swelling on a continuous scale, similar to SD-OCT. Here, we select features from more commonly available 2D fundus images and use them to predict ONH volume. Twenty-six features were extracted from each of 48 color fundus images. The features include attributes of the blood vessels, optic nerve head, and peripapillary retina areas. These features were used in a regression analysis to predict ONH volume, as computed by a segmentation of the SD-OCT image. The results of the regression analysis yielded a mean square error of 2.43 mm3 and a correlation coefficient between computed and predicted volumes of R = 0:771, which suggests that ONH volume may be predicted from fundus features alone.

Examples of Current and Future Uses of Neural-Net Image Processing for Aerospace Applications

NASA Technical Reports Server (NTRS)

Decker, Arthur J.

2004-01-01

Feed forward artificial neural networks are very convenient for performing correlated interpolation of pairs of complex noisy data sets as well as detecting small changes in image data. Image-to-image, image-to-variable and image-to-index applications have been tested at Glenn. Early demonstration applications are summarized including image-directed alignment of optics, tomography, flow-visualization control of wind-tunnel operations and structural-model-trained neural networks. A practical application is reviewed that employs neural-net detection of structural damage from interference fringe patterns. Both sensor-based and optics-only calibration procedures are available for this technique. These accomplishments have generated the knowledge necessary to suggest some other applications for NASA and Government programs. A tomography application is discussed to support Glenn's Icing Research tomography effort. The self-regularizing capability of a neural net is shown to predict the expected performance of the tomography geometry and to augment fast data processing. Other potential applications involve the quantum technologies. It may be possible to use a neural net as an image-to-image controller of an optical tweezers being used for diagnostics of isolated nano structures. The image-to-image transformation properties also offer the potential for simulating quantum computing. Computer resources are detailed for implementing the black box calibration features of the neural nets.

Optical polarimetry of KIC 8462852 in 2017 May-August

NASA Astrophysics Data System (ADS)

Steele, I. A.; Copperwheat, C. M.; Jermak, H. E.; Kennedy, G. M.; Lamb, G. P.

2018-01-01

We present optical polarimetry in the period of 2017 May-August of the enigmatic `dipping' star KIC 8462852. During that period, three ˜1 per cent photometric dips were reported by other observers. We measured the average absolute polarization of the source, and find no excess or unusual polarization compared to a nearby comparison star. We place tight upper limits on any change in the degree of polarization of the source between epochs in-dip and out-of-dip of <0.1 per cent (8500 Å) and <0.2 per cent (7050 Å and 5300 Å). How our limits are interpreted depends on the specific model being considered. If the whole stellar disc were covered by material with an optical depth of ˜0.01, then the fractional polarization introduced by this material must be less than 10-20 per cent. While our non-detection does not constrain the comet scenario, it predicts that even modest amounts of dust that have properties similar to Solar system comets may be detectable. We note that the sensitivity of our method scales with the depth of the dip. Should a future ˜20 per cent photometric dip be observed (as was previously detected by Kepler), our method would constrain any induced polarization associated with any occulting material to 0.5-1.0 per cent.

An improved analytic function for predicting light fluence rate in circular fields on a semi-infinite geometry

NASA Astrophysics Data System (ADS)

Zhu, Timothy C.; Lu, Amy; Ong, Yi-Hong

2016-03-01

Accurate determination of in-vivo light fluence rate is critical for preclinical and clinical studies involving photodynamic therapy (PDT). This study compares the longitudinal light fluence distribution inside biological tissue in the central axis of a 1 cm diameter circular uniform light field for a range of in-vivo tissue optical properties (absorption coefficients (μa) between 0.01 and 1 cm-1 and reduced scattering coefficients (μs') between 2 and 40 cm-1). This was done using Monte-Carlo simulations for a semi-infinite turbid medium in an air-tissue interface. The end goal is to develop an analytical expression that would fit the results from the Monte Carlo simulation for both the 1 cm diameter circular beam and the broad beam. Each of these parameters is expressed as a function of tissue optical properties. These results can then be compared against the existing expressions in the literature for broad beam for analysis in both accuracy and applicable range. Using the 6-parameter model, the range and accuracy for light transport through biological tissue is improved and may be used in the future as a guide in PDT for light fluence distribution for known tissue optical properties.

Planar integrated optics, a new solution in optical instrumentation

NASA Astrophysics Data System (ADS)

Haguenauer, P.

2017-11-01

Planar integrated optics present an attractive solution for future instrumentation, both in ground and space based applications. The technologies used in the manufacturing of such components, supported by research laboratories as well as industries, are mature enough to provide complex devices.

Design, Construction, and Testing of Lightweight X-ray Mirror Modules

NASA Technical Reports Server (NTRS)

McClelland, Ryan S.; Biskach, Michael P.; Chan, Kai-Wing; Espina, Rebecca A.; Hohl, Bruce R.; Matson, Elizabeth A.; Saha, Timo C.; Zhang, William W.

2013-01-01

Lightweight and high resolution optics are needed for future space-based X-ray telescopes to achieve advances in high-energy astrophysics. The Next Generation X-ray Optics (NGXO) team at NASA GSFC is nearing mission readiness for a 10 arc-second Half Power Diameter (HPD) slumped glass mirror technology while laying the groundwork for a future 1-2 arc-second technology based on polished silicon mirrors. Technology Development Modules (TDMs) have been designed, fabricated, integrated with mirrors segments, and extensively tested to demonstrate technology readiness. Tests include X-ray performance, thermal vacuum, acoustic load, and random vibration. The thermal vacuum and acoustic load environments have proven relatively benign, while the random vibration environment has proven challenging due to large input amplification at frequencies above 500 Hz. Epoxy selection, surface preparation, and larger bond area have increased bond strength while vibration isolation has decreased vibration amplification allowing for space launch requirements to be met in the near term. The next generation of TDMs, which demonstrates a lightweight structure supporting more mirror segments, is currently being fabricated. Analysis predicts superior performance characteristics due to the use of E-60 Beryllium-Oxide Metal Matrix Composite material, with only a modest cost increase. These TDMs will be larger, lighter, stiffer, and stronger than the current generation. Preliminary steps are being taken to enable mounting and testing of 1-2 arc-second mirror segments expected to be available in the future. A Vertical X-ray Test Facility (VXTF) will minimize module gravity distortion and allow for less constrained mirror mounts, such as fully kinematic mounts. Permanent kinematic mounting into a modified TDM has been demonstrated to achieve 2 arc-second level distortion free alignment.

Enhancement of the transverse magneto-optical Kerr effect via resonant tunneling in trilayers containing magneto-optical metals

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

Girón-Sedas, J. A.; Centro de Investigación e Innovación en Bioinformática y Fotónica - CIBioFI, AA 25360 Cali; Mejía-Salazar, J. R., E-mail: jrmejia3146@gmail.com

We propose a way to enhance the transverse magneto-optical Kerr effect, by the excitation of resonant tunneling modes, in subwavelength trilayer structures featuring a dielectric slab sandwiched between two magneto-optical metallic layers. Depending on the magneto-optical layer widths, the proposed system may exhibit an extraordinary transverse magneto-optical Kerr effect, which makes it very attractive for the design and engineering of thin-film magneto-optical-based devices for future photonic circuits or fiber optical-communication systems.

Optical computing research

NASA Astrophysics Data System (ADS)

Goodman, Joseph W.

1987-10-01

Work Accomplished: OPTICAL INTERCONNECTIONS - the powerful interconnect abilities of optical beams have led much optimism about the possible roles for optics in solving interconnect problems at various levels of computer architecture. Examined were the powerful requirements of optical interconnects at the gate-to-gate and chip-to-chip levels. OPTICAL NEUTRAL NETWORKS - basic studies of the convergence properties on the Holfield model, based on mathematical approach - graph theory. OPTICS AND ARTIFICIAL INTELLIGENCE - review the field of optical processing and artificial intelligence, with the aim of finding areas that might be particularly attractive for future investigation(s).

InAs/GaSb type-II superlattices versus HgCdTe ternary alloys: future prospect

NASA Astrophysics Data System (ADS)

Rogalski, A.

2017-10-01

InAs/GaSb T2SL photodetectors offer similar performance to HgCdTe at an equivalent cutoff wavelength, but with a sizeable penalty in operating temperature, due to the inherent difference in Shockley-Read lifetimes. It is predicted that since the future IR systems will be based on the room temperature operation of depletion-current limited arrays with pixel densities that are fully consistent with background- and diffraction-limited performance due to the system optics, the material system with long Shockley-Read lifetime will be required. Since T2SLs are much resisted in attempts to improve its SR lifetime, currently the only material that meets this requirement is HgCdTe. Due to less ionic chemical bonding, III-V semiconductors are more robust than their II-VI counterparts. As a result, III-V-based FPAs excel in operability, spatial uniformity, temporal stability, scalability, producibility, and affordability - the so-called "ibility" advantages.

MgB2 Thin-Film Bolometer for Applications in Far-Infrared Instruments on Future Planetary Missions

NASA Technical Reports Server (NTRS)

Lakew, B.; Aslam, S.; Brasunas, J.; Cao, N.; Costen, N.; La, A.; Stevenson, T.; Waczynski, A.

2012-01-01

A SiN membrane based MgB2 thin-film bolometer, with a non-optimized absorber, has been fabricated that shows an electrical noise equivalent power of 256 fW/square root Hz operating at 30 Hz in the 8.5 - 12.35 micron spectral bandpass. This value corresponds to an electrical specific detectivity of 7.6 x 10(exp 10) cm square root Hz/W. The bolometer shows a measured blackbody (optical) specific detectivity of 8.8 x 10(exp 9) cm square root Hz/W, with a responsivity of 701.5 kV/W and a first-order time constant of 5.2 ms. It is predicted that with the inclusion of a gold black absorber that a blackbody specific detectivity of 6.4 x 10(exp 10) cm/square root Hz/W at an operational frequency of 10 Hz, can be realized for integration into future planetary exploration instrumentation where high sensitivity is required in the 17 - 250 micron spectral wavelength range.

Deep space target location with Hubble Space Telescope (HST) and Hipparcos data

NASA Technical Reports Server (NTRS)

Null, George W.

1988-01-01

Interplanetary spacecraft navigation requires accurate a priori knowledge of target positions. A concept is presented for attaining improved target ephemeris accuracy using two future Earth-orbiting optical observatories, the European Space Agency (ESA) Hipparcos observatory and the Nasa Hubble Space Telescope (HST). Assuming nominal observatory performance, the Hipparcos data reduction will provide an accurate global star catalog, and HST will provide a capability for accurate angular measurements of stars and solar system bodies. The target location concept employs HST to observe solar system bodies relative to Hipparcos catalog stars and to determine the orientation (frame tie) of these stars to compact extragalactic radio sources. The target location process is described, the major error sources discussed, the potential target ephemeris error predicted, and mission applications identified. Preliminary results indicate that ephemeris accuracy comparable to the errors in individual Hipparcos catalog stars may be possible with a more extensive HST observing program. Possible future ground and spacebased replacements for Hipparcos and HST astrometric capabilities are also discussed.

Free-space optical communications in support of future manned space flight

NASA Technical Reports Server (NTRS)

Stephens, Elaine M.

1990-01-01

Four areas of research in optical communications in support of future manned space missions being carried out at Johnson Space Center are discussed. These are the Space Station Freedom proximity operations, direct LEO-to-ground communications, IR voice communications inside manned spacecraft, and deep space and lunar satellite operations. The background, requirements, and scenario for each of these areas of research are briefly described.

History of optical theory of reflecting telescopes and implications for future projects

NASA Astrophysics Data System (ADS)

Wilson, Raymond N.

1997-03-01

This contribution, The History of Optical Theory of Reflecting Telescopes and Implications for Future Projects, is a shortened form of the Karl Schwarzschild lecture given in Bochum in September 1993. Some material has been added from an invited paper given in Padua in December 1992. For a full account, with figures and tables, the reader is referred to these two papers.

Prediction of the limit of detection of an optical resonant reflection biosensor.

PubMed

Hong, Jongcheol; Kim, Kyung-Hyun; Shin, Jae-Heon; Huh, Chul; Sung, Gun Yong

2007-07-09

A prediction of the limit of detection of an optical resonant reflection biosensor is presented. An optical resonant reflection biosensor using a guided-mode resonance filter is one of the most promising label-free optical immunosensors due to a sharp reflectance peak and a high sensitivity to the changes of optical path length. We have simulated this type of biosensor using rigorous coupled wave theory to calculate the limit of detection of the thickness of the target protein layer. Theoretically, our biosensor has an estimated ability to detect thickness change approximately the size of typical antigen proteins. We have also investigated the effects of the absorption and divergence of the incident light on the detection ability of the biosensor.

OPTOELECTRONICS, FIBER OPTICS, AND OTHER ASPECTS OF QUANTUM ELECTRONICS: Nonlinear optical devices: basic elements of a future optical digital computer?

NASA Astrophysics Data System (ADS)

Fischer, R.; Müller, R.

1989-08-01

It is shown that nonlinear optical devices are the most promising elements for an optical digital supercomputer. The basic characteristics of various developed nonlinear elements are presented, including bistable Fabry-Perot etalons, interference filters, self-electrooptic effect devices, quantum-well devices utilizing transitions between the lowest electron states in the conduction band of GaAs, etc.

Optical Tecnology Developments in Biomedicine: History, Current and Future

PubMed Central

Nioka, Shoko; Chen, Yu

2011-01-01

Biomedical optics is a rapidly emerging field for medical imaging and diagnostics. This paper reviews several biomedical optical technologies that have been developed and translated for either clinical or pre-clinical applications. Specifically, we focus on the following technologies: 1) near-infrared spectroscopy and tomography, 2) optical coherence tomography, 3) fluorescence spectroscopy and imaging, and 4) optical molecular imaging. There representative biomedical applications are also discussed here. PMID:23905030

Keyboarding: An Important Skill for the Office of the Future.

ERIC Educational Resources Information Center

Burford, Anna M.

1980-01-01

Defines the components of the office of the future: data processing, micrographics, optical character recognition, telecommunications, and word processing. Also discusses teacher responsibility, student preparation, future challenges, and teacher awareness. (CT)

Demonstration of fully enabled data center subsystem with embedded optical interconnect

NASA Astrophysics Data System (ADS)

Pitwon, Richard; Worrall, Alex; Stevens, Paul; Miller, Allen; Wang, Kai; Schmidtke, Katharine

2014-03-01

The evolution of data storage communication protocols and corresponding in-system bandwidth densities is set to impose prohibitive cost and performance constraints on future data storage system designs, fuelling proposals for hybrid electronic and optical architectures in data centers. The migration of optical interconnect into the system enclosure itself can substantially mitigate the communications bottlenecks resulting from both the increase in data rate and internal interconnect link lengths. In order to assess the viability of embedding optical links within prevailing data storage architectures, we present the design and assembly of a fully operational data storage array platform, in which all internal high speed links have been implemented optically. This required the deployment of mid-board optical transceivers, an electro-optical midplane and proprietary pluggable optical connectors for storage devices. We present the design of a high density optical layout to accommodate the midplane interconnect requirements of a data storage enclosure with support for 24 Small Form Factor (SFF) solid state or rotating disk drives and the design of a proprietary optical connector and interface cards, enabling standard drives to be plugged into an electro-optical midplane. Crucially, we have also modified the platform to accommodate longer optical interconnect lengths up to 50 meters in order to investigate future datacenter architectures based on disaggregation of modular subsystems. The optically enabled data storage system has been fully validated for both 6 Gb/s and 12 Gb/s SAS data traffic conveyed along internal optical links.

HF Accelerated Electron Fluxes, Spectra, and Ionization

NASA Astrophysics Data System (ADS)

Carlson, Herbert C.; Jensen, Joseph B.

2015-10-01

Wave particle interactions, an essential aspect of laboratory, terrestrial, and astrophysical plasmas, have been studied for decades by transmitting high power HF radio waves into Earth's weakly ionized space plasma, to use it as a laboratory without walls. Application to HF electron acceleration remains an active area of research (Gurevich in Usp Fizicheskikh Nauk 177(11):1145-1177, 2007) today. HF electron acceleration studies began when plasma line observations proved (Carlson et al. in J Atmos Terr Phys 44:1089-1100, 1982) that high power HF radio wave-excited processes accelerated electrons not to ~eV, but instead to -100 times thermal energy (10 s of eV), as a consequence of inelastic collision effects on electron transport. Gurevich et al (J Atmos Terr Phys 47:1057-1070, 1985) quantified the theory of this transport effect. Merging experiment with theory in plasma physics and aeronomy, enabled prediction (Carlson in Adv Space Res 13:1015-1024, 1993) of creating artificial ionospheres once ~GW HF effective radiated power could be achieved. Eventual confirmation of this prediction (Pedersen et al. in Geophys Res Lett 36:L18107, 2009; Pedersen et al. in Geophys Res Lett 37:L02106, 2010; Blagoveshchenskaya et al. in Ann Geophys 27:131-145, 2009) sparked renewed interest in optical inversion to estimate electron spectra in terrestrial (Hysell et al. in J Geophys Res Space Phys 119:2038-2045, 2014) and planetary (Simon et al. in Ann Geophys 29:187-195, 2011) atmospheres. Here we present our unpublished optical data, which combined with our modeling, lead to conclusions that should meaningfully improve future estimates of the spectrum of HF accelerated electron fluxes. Photometric imaging data can significantly improve detection of emissions near ionization threshold, and confirm depth of penetration of accelerated electrons many km below the excitation altitude. Comparing observed to modeled emission altitude shows future experiments need electron density profiles to derive more accurate HF electron flux spectra.

Research on Retro-reflecting Modulation in Space Optical Communication System

NASA Astrophysics Data System (ADS)

Zhu, Yifeng; Wang, Guannan

2018-01-01

Retro-reflecting modulation space optical communication is a new type of free space optical communication technology. Unlike traditional free space optical communication system, it applys asymmetric optical systems to reduce the size, weight and power consumption of the system and can effectively solve the limits of traditional free space optical communication system application, so it can achieve the information transmission. This paper introduces the composition and working principle of retro-reflecting modulation optical communication system, analyzes the link budget of this system, reviews the types of optical system and optical modulator, summarizes this technology future research direction and application prospects.

Optically Tuned MM-Wave IMPATT Source.

DTIC Science & Technology

1987-07-01

phase of the work has been extended and generalised. Accuracy of the theory in predicting tuning at the higher oscillator voltage swings has been greatly...Accuracy of the theory in predicting tuning at the higher oscillator voltage swings has been greatly improved by reformulating the Bessel function...voltage modulation and a peak optically injected locking current of 100 pA the predicted ftl locking range would be 540MHz, a practicaUy useful value. 4

Numerical models of laser fusion of intestinal tissues.

PubMed

Pearce, John A

2009-01-01

Numerical models of continuous wave Tm:YAG thermal fusion in rat intestinal tissues were compared to experiment. Optical and thermal FDM models that included tissue damage based on Arrhenius kinetics were used to predict birefringence loss in collagen as the standard of comparison. The models also predicted collagen shrinkage, jellification and water loss. The inclusion of variable optical and thermal properties is essential to achieve favorable agreement between predicted and measured damage boundaries.

Identified state-space prediction model for aero-optical wavefronts

NASA Astrophysics Data System (ADS)

Faghihi, Azin; Tesch, Jonathan; Gibson, Steve

2013-07-01

A state-space disturbance model and associated prediction filter for aero-optical wavefronts are described. The model is computed by system identification from a sequence of wavefronts measured in an airborne laboratory. Estimates of the statistics and flow velocity of the wavefront data are shown and can be computed from the matrices in the state-space model without returning to the original data. Numerical results compare velocity values and power spectra computed from the identified state-space model with those computed from the aero-optical data.

Predicting threshold and location of laser damage on optical surfaces

DOEpatents

Siekhaus, Wigbert

1987-01-01

An apparatus useful in the prediction of the damage threshold of various optical devices, the location of weak spots on such devices and the location, identification, and elimination of optical surface impurities comprising, a focused and pulsed laser, an photo electric detector/imaging means, and a timer. The weak spots emit photoelectrons when subjected to laser intensities that are less than the intensity actually required to produce the damage. The weak spots may be eliminated by sustained exposure to the laser beam.

Theoretical model and simulations for a cw exciplex pumped alkali laser.

PubMed

Huang, Wei; Tan, Rongqing; Li, Zhiyong; Lu, Xiaochuan

2015-12-14

The Exciplex Pumped Alkali Laser (XPAL) system, which is similar to DPAL (Diode Pumped Alkali vapor Laser), has been demonstrated in mixtures of Cs vapor, Ar, with and without ethane. Unlike DPAL, it uses the broadband absorption blue satellite of the alkali D₂ line, created by naturally occuring collision pairs. For example, Cs-Ar collision pairs have an absorption width which is as wide as the one of commercial semiconductor diode lasers. A continuous wave XPAL four-level theoretical model is presented in this paper. More factors are considered, such as the spectral dependence of pumped laser absorption for broadband pumping and the longitudinal population variation. Some intra-cavity details, such as longitudinal distributions of pumped laser and alkali laser, can also be solved well. The predictions of optical-to-optical efficiency as a function of temperature and pumped laser intensity are presented. The model predicts that there is an optimum value of temperature or pumped laser intensity. The analysis of the influence of cell length on optical-to-optical efficiency shows that a better performance can be achieved when using longer cell. The prediction of influence of Ar concentration and reflectivity of output coupler shows that higher optical-to-optical efficiency could be achieved if lower reflectivity of output coupler and higher Ar concentration are used. The optical-to-optical efficiency as high as 84% achieved by optimizing configuration with the pumped intensity of 5 × 10⁷ W/cm² presented shows that broadband pumped four-level XPAL system has a potential of high optical-to-optical efficiency.

Adaptive metalenses with simultaneous electrical control of focal length, astigmatism, and shift.

PubMed

She, Alan; Zhang, Shuyan; Shian, Samuel; Clarke, David R; Capasso, Federico

2018-02-01

Focal adjustment and zooming are universal features of cameras and advanced optical systems. Such tuning is usually performed longitudinally along the optical axis by mechanical or electrical control of focal length. However, the recent advent of ultrathin planar lenses based on metasurfaces (metalenses), which opens the door to future drastic miniaturization of mobile devices such as cell phones and wearable displays, mandates fundamentally different forms of tuning based on lateral motion rather than longitudinal motion. Theory shows that the strain field of a metalens substrate can be directly mapped into the outgoing optical wavefront to achieve large diffraction-limited focal length tuning and control of aberrations. We demonstrate electrically tunable large-area metalenses controlled by artificial muscles capable of simultaneously performing focal length tuning (>100%) as well as on-the-fly astigmatism and image shift corrections, which until now were only possible in electron optics. The device thickness is only 30 μm. Our results demonstrate the possibility of future optical microscopes that fully operate electronically, as well as compact optical systems that use the principles of adaptive optics to correct many orders of aberrations simultaneously.

Materials Development for Next Generation Optical Fiber

PubMed Central

Ballato, John; Dragic, Peter

2014-01-01

Optical fibers, the enablers of the Internet, are being used in an ever more diverse array of applications. Many of the rapidly growing deployments of fibers are in high-power and, particularly, high power-per-unit-bandwidth systems where well-known optical nonlinearities have historically not been especially consequential in limiting overall performance. Today, however, nominally weak effects, most notably stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS) are among the principal phenomena restricting continued scaling to higher optical power levels. In order to address these limitations, the optical fiber community has focused dominantly on geometry-related solutions such as large mode area (LMA) designs. Since such scattering, and all other linear and nonlinear optical phenomena including higher order mode instability (HOMI), are fundamentally materials-based in origin, this paper unapologetically advocates material solutions to present and future performance limitations. As such, this paper represents a ‘call to arms’ for material scientists and engineers to engage in this opportunity to drive the future development of optical fibers that address many of the grand engineering challenges of our day. PMID:28788683

Excitons in atomically thin 2D semiconductors and their applications

DOE PAGES

Xiao, Jun; Zhao, Mervin; Wang, Yuan; ...

2017-01-01

The research on emerging layered two-dimensional (2D) semiconductors, such as molybdenum disulfide (MoS 2), reveals unique optical properties generating significant interest. Experimentally, these materials were observed to host extremely strong light-matter interactions as a result of the enhanced excitonic effect in two dimensions. Thus, understanding and manipulating the excitons are crucial to unlocking the potential of 2D materials for future photonic and optoelectronic devices. Here in this review, we unravel the physical origin of the strong excitonic effect and unique optical selection rules in 2D semiconductors. In addition, control of these excitons by optical, electrical, as well as mechanical meansmore » is examined. Finally, the resultant devices such as excitonic light emitting diodes, lasers, optical modulators, and coupling in an optical cavity are overviewed, demonstrating how excitons can shape future 2D optoelectronics.« less

Optical and magneto-optical properties of AuMnSn

NASA Astrophysics Data System (ADS)

Lee, S. J.; Janssen, Y.; Park, J. M.; Cho, B. K.

2006-03-01

We have measured room-temperature magneto-optical properties of AuMnSn on a single-crystalline sample. The maximum polar Kerr rotation was predicted to be very large, about -0.7° at 1.2eV [L. Offernes, P. Ravindran, and A. Kjekshus, Appl. Phys. Lett. 82, 2862 (2003)]. We found the experimental maximum Kerr rotation and ellipticity were about three times smaller than predicted and appeared at energies about 0.6eV higher than predicted, which is possibly due to inaccurate handling of the theory based on the local spin-density approximation to density-function theory for the localized 4d and 5d orbitals in AuMnSn.

Anomalous nonlinear absorption in epsilon-near-zero materials: optical limiting and all-optical control.

PubMed

Vincenti, M A; de Ceglia, D; Scalora, Michael

2016-08-01

We investigate nonlinear absorption in films of epsilon-near-zero materials. The combination of large local electric fields at the fundamental frequency and material losses at the harmonic frequencies induce unusual intensity-dependent phenomena. We predict that the second-order nonlinearity of a low-damping, epsilon-near-zero slab produces an optical limiting effect that mimics a two-photon absorption process. Anomalous absorption profiles that depend on low permittivity values at the pump frequency are also predicted for third-order nonlinearities. These findings suggest new opportunities for all-optical light control and novel ways to design reconfigurable and tunable nonlinear devices.

Optical performance assessment under environmental and mechanical perturbations in large, deployable telescopes

NASA Astrophysics Data System (ADS)

Folley, Christopher; Bronowicki, Allen

2005-09-01

Prediction of optical performance for large, deployable telescopes under environmental conditions and mechanical disturbances is a crucial part of the design verification process of such instruments for all phases of design and operation: ground testing, commissioning, and on-orbit operation. A Structural-Thermal-Optical-Performance (STOP) analysis methodology is often created that integrates the output of one analysis with the input of another. The integration of thermal environment predictions with structural models is relatively well understood, while the integration of structural deformation results into optical analysis/design software is less straightforward. A Matlab toolbox has been created that effectively integrates the predictions of mechanical deformations on optical elements generated by, for example, finite element analysis, and computes optical path differences for the distorted prescription. The engine of the toolbox is the real ray-tracing algorithm that allows the optical surfaces to be defined in a single, global coordinate system thereby allowing automatic alignment of the mechanical coordinate system with the optical coordinate system. Therefore, the physical location of the optical surfaces is identical in the optical prescription and the finite element model. The application of rigid body displacements to optical surfaces, however, is more general than for use solely in STOP analysis, such as the analysis of misalignments during the commissioning process. Furthermore, all the functionality of Matlab is available for optimization and control. Since this is a new tool for use on flight programs, it has been verified against CODE V. The toolbox' functionality, to date, is described, verification results are presented, and, as an example of its utility, results of a thermal distortion analysis are presented using the James Webb Space Telescope (JWST) prescription.

Mission Life Thermal Analysis and Environment Correlation for the Lunar Reconnaissance Orbiter

NASA Technical Reports Server (NTRS)

Garrison, Matthew B.; Peabody, Hume

2012-01-01

Standard thermal analysis practices include stacking worst-case conditions including environmental heat loads, thermo-optical properties and orbital beta angles. This results in the design being driven by a few bounding thermal cases, although those cases may only represent a very small portion of the actual mission life. The NASA Goddard Space Flight Center Thermal Branch developed a procedure to predict the flight temperatures over the entire mission life, assuming a known beta angle progression, variation in the thermal environment, and a degradation rate in the coatings. This was applied to the Global Precipitation Measurement core spacecraft. In order to assess the validity of this process, this work applies the similar process to the Lunar Reconnaissance Orbiter. A flight-correlated thermal model was exercised to give predictions of the thermal performance over the mission life. These results were then compared against flight data from the first two years of the spacecraft s use. This is used to validate the process and to suggest possible improvements for future analyses.

Optical and infrared lasers

NASA Technical Reports Server (NTRS)

Javan, A.

1978-01-01

Quantum mechanical predictions for the gain of an optically pumped CW FIR laser are presented for cases in which one or both of the pump and FIR transitions are pressure or Doppler broadened. The results are compared to those based on the rate equation model. Some of the quantum mechanical predictions are verified in CH3OH.

The Mount Wilson optical interferometer: The first automated instrument and the prospects for lunar interferometry

NASA Technical Reports Server (NTRS)

Johnston, Ken J.; Mozurkewich, D.; Simon, R. S.; Shao, Michael; Colavita, M.

1992-01-01

Before contemplating an optical interferometer on the Moon one must first review the accomplishments achieved by this technology in scientific applications for astronomy. This will be done by presenting the technical status of optical interferometry as achieved by the Mount Wilson Optical Interferometer. The further developments needed for a future lunar-based interferometer are discussed.

Freeform Optics: current challenges for future serial production

NASA Astrophysics Data System (ADS)

Schindler, C.; Köhler, T.; Roth, E.

2017-10-01

One of the major developments in optics industry recently is the commercial manufacturing of freeform surfaces for optical mid- and high performance systems. The loss of limitation on rotational symmetry enables completely new optical design solutions - but causes completely new challenges for the manufacturer too. Adapting the serial production from radial-symmetric to freeform optics cannot be done just by the extension of machine capabilities and software for every process step. New solutions for conventional optics productions or completely new process chains are necessary.

New trends in laser satellite communications: design and limitations

NASA Astrophysics Data System (ADS)

Císar, J.; Wilfert, O.; Fanjul-Vélez, F.; Ortega-Quijano, N.; Arce-Diego, J. L.

2008-11-01

Optical communications offer a capable alternative to radio frequency (RF) communications for applications where high data-rate is required. This technology is particularly promising and challenging in the field of future inter-satellite communications. The term laser satellite communications (LSC) stands for optical links between satellites and/or high altitude platforms (HAPs). However, optical links between an earth station and a satellite or HAPs can be also involved. This work gives an overview of nowadays laser satellite communications. Particularly, it is focused on the factors causing degradation of the optical beam in the atmosphere. If an optical link passes through the atmosphere, it suffers from various influences such as attenuation due to absorption and scattering, intensity fluctuations due to atmospheric turbulence and background radiation. Furthermore, platform vibrations cause mispointing and following tracking losses. Suitable devices and used pointing and tracking system for laser satellite communications are discussed. At the end, various scenarios of the optical links and calculations of their power link budgets and limitations are designed. Implemented software is used for calculation of optical links. This work proves that the Free Space Optics (FSO) systems on mobile platforms, like satellites and HAPs are a promising solution for future communication networks.

Laser Optical Disk: The Coming Revolution in On-Line Storage.

ERIC Educational Resources Information Center

Fujitani, Larry

1984-01-01

Review of similarities and differences between magnetic-based and optical disk drives includes a discussion of the electronics necessary for their operation; describes benefits, possible applications, and future trends in development of laser-based drives; and lists manufacturers of laser optical disk drives. (MBR)

MOEMS optical delay line for optical coherence tomography

NASA Astrophysics Data System (ADS)

Choudhary, Om P.; Chouksey, S.; Sen, P. K.; Sen, P.; Solanki, J.; Andrews, J. T.

2014-09-01

Micro-Opto-Electro-Mechanical optical coherence tomography, a lab-on-chip for biomedical applications is designed, studied, fabricated and characterized. To fabricate the device standard PolyMUMPS processes is adopted. We report the utilization of electro-optic modulator for a fast scanning optical delay line for time domain optical coherence tomography. Design optimization are performed using Tanner EDA while simulations are performed using COMSOL. The paper summarizes various results and fabrication methodology adopted. The success of the device promises a future hand-held or endoscopic optical coherence tomography for biomedical applications.

Transient Negative Optical Nonlinearity of Indium Oxide Nanorod Arrays in the Full-Visible Range

DOE PAGES

Guo, Peijun; Chang, Robert P. H.; Schaller, Richard D.

2017-06-09

Dynamic control of the optical response of materials at visible wavelengths is key to future metamaterials and photonic integrated circuits. Here we demonstrate large amplitude, negative optical nonlinearity (Δ n from -0.05 to -0.09) of indium oxide nanorod arrays in the full-visible range. We experimentally quantify and theoretically calculate the optical nonlinearity, which arises from the modifications of interband optical transitions. Furthermore, the approach towards negative optical nonlinearity can be generalized to other transparent semiconductors and opens door to reconfigurable, sub-wavelength optical components.

Study of fiber optics standardization, reliability, and applications

NASA Technical Reports Server (NTRS)

1980-01-01

The use of fiber optics in space applications is investigated. Manufacturers and users detailed the problems they were having with the use or manufacture of fiber optic components. The general consensus of all the companies/agencies interviewed is that fiber optics is a maturing technology and will definitely have a place in future NASA system designs. The use of fiber optics was found to have two main advantages - weight savings and increased bandwidth.

Advanced adaptive optics technology development

NASA Astrophysics Data System (ADS)

Olivier, Scot S.

2002-02-01

The NSF Center for Adaptive Optics (CfAO) is supporting research on advanced adaptive optics technologies. CfAO research activities include development and characterization of micro-electro-mechanical systems (MEMS) deformable mirror (DM) technology, as well as development and characterization of high-resolution adaptive optics systems using liquid crystal (LC) spatial light modulator (SLM) technology. This paper presents an overview of the CfAO advanced adaptive optics technology development activities including current status and future plans.

A dynamic Monte Carlo model for predicting radiant exposure distribution in dental composites: model development and verifications

NASA Astrophysics Data System (ADS)

Chen, Yin-Chu; Ferracane, Jack L.; Prahl, Scott A.

2005-03-01

Photo-cured dental composites are widely used in dental practices to restore teeth due to the esthetic appearance of the composites and the ability to cure in situ. However, their complex optical characteristics make it difficult to understand the light transport within the composites and to predict the depth of cure. Our previous work showed that the absorption and scattering coefficients of the composite changed after the composite was cured. The static Monte Carlo simulation showed that the penetration of radiant exposures differed significantly for cured and uncured optical properties. This means that a dynamic model is required for accurate prediction of radiant exposure in the composites. The purpose of this study was to develop and verify a dynamic Monte Carlo (DMC) model simulating light propagation in dental composites that have dynamic optical properties while photons are absorbed. The composite was divided into many small cubes, each of which had its own scattering and absorption coefficients. As light passed through the composite, the light was scattered and absorbed. The amount of light absorbed in each cube was calculated using Beer's Law and was used to determine the next optical properties in that cube. Finally, the predicted total reflectance and transmittance as well as the optical property during curing were verified numerically and experimentally. Our results showed that the model predicted values agreed with the theoretical values within 1% difference. The DMC model results are comparable with experimental results within 5% differences.

The Safety and Predictability of Implanting Autologous Lenticule Obtained by SMILE for Hyperopia.

PubMed

Sun, Ling; Yao, Peijun; Li, Meiyan; Shen, Yang; Zhao, Jing; Zhou, Xingtao

2015-06-01

To evaluate the safety, effectiveness, stability, and predictability of implanting autologous lenticules obtained from small incision lenticule extraction for the treatment of hyperopia. Five patients (10 eyes) with one myopic eye and one hyperopic eye were enrolled. The myopic eye was treated with small incision lenticule extraction; a lenticule was extracted and subsequently implanted in the hyperopic eye. Follow-up was at 1 day, 1, 3, 6, and 9 months, and 1 year postoperatively. Patients received a complete ophthalmologic examination at each visit, including uncorrected distance visual acuity, corrected distance visual acuity, anterior segment optical coherence tomography, and corneal topography. There were no complications in any eye during follow-up. Compared with preoperative levels, at the last follow-up visit the eyes with lenticule implantation showed mean spherical equivalent reduced by 5.53 diopters (residual spherical equivalent was +1.13 to -2.63 diopters), mean uncorrected distance visual acuity increased approximately two lines (approximately 20/63 to 20/40 Snellen), and corrected distance visual acuity in 4 (80%) eyes gained one line, 2 (40%) eyes gained two lines, and 1 (20%) eye gained more than two lines. There was no significant difference (P > .05) in spherical equivalent compared with 1 day postoperatively and the last follow-up visit. Corneal topography showed that the lenticule was uniform and located well; anterior segment optical coherence tomography images showed that the lenticule was transparent and the demarcation line was visible. Implanting an autologous lenticule obtained by small incision lenticule extraction for hyperopia might be safe, effective, and stable, but its predictability should be improved in the future. Copyright 2015, SLACK Incorporated.

Corner Wrinkling at a Square Membrane Due to Symmetric Mechanical Loads

NASA Technical Reports Server (NTRS)

Blandino, Joseph R.; Johnston, John D.; Dharamsi, Urmil K.; Brodeur, Stephen J. (Technical Monitor)

2001-01-01

Thin-film membrane structures are under consideration for use in many future gossamer spacecraft systems. Examples include sunshields for large aperture telescopes, solar sails, and membrane optics. The development of capabilities for testing and analyzing pre-tensioned, thin film membrane structures is an important and challenging aspect of gossamer spacecraft technology development. This paper presents results from experimental and computational studies performed to characterize the wrinkling behavior of thin-fi[m membranes under mechanical loading. The test article is a 500 mm square membrane subjected to symmetric comer loads. Data is presented for loads ranging from 0.49 N to 4.91 N. The experimental results show that as the load increases the number of wrinkles increases, while the wrinkle amplitude decreases. The computational model uses a finite element implementation of Stein-Hedgepeth membrane wrinkling theory to predict the behavior of the membrane. Comparisons were made with experimental results for the wrinkle angle and wrinkled region. There was reasonably good agreement between the measured wrinkle angle and the predicted directions of the major principle stresses. The shape of the wrinkle region predicted by the finite element model matches that observed in the experiments; however, the size of the predicted region is smaller than that determined in the experiments.

Active-Optical Sensors Using Red NDVI Compared to Red Edge NDVI for Prediction of Corn Grain Yield in North Dakota, U.S.A.

PubMed Central

Sharma, Lakesh K.; Bu, Honggang; Denton, Anne; Franzen, David W.

2015-01-01

Active-optical sensor readings from an N non-limiting area standard established within a farm field are used to predict yield in the standard. Lower yield predictions from sensor readings obtained from other parts of the field outside of the N non-limiting standard area indicate a need for supplemental N. Active-optical sensor algorithms for predicting corn (Zea mays, L.) yield to direct in-season nitrogen (N) fertilization in corn utilize red NDVI (normalized differential vegetative index). Use of red edge NDVI might improve corn yield prediction at later growth stages when corn leaves cover the inter-row space resulting in “saturation” of red NDVI readings. The purpose of this study was to determine whether the use of red edge NDVI in two active-optical sensors (GreenSeeker™ and Holland Scientific Crop Circle™) improved corn yield prediction. Nitrogen rate experiments were established at 15 sites in North Dakota (ND). Sensor readings were conducted at V6 and V12 corn. Red NDVI and red edge NDVI were similar in the relationship of readings with yield at V6. At V12, the red edge NDVI was superior to the red NDVI in most comparisons, indicating that it would be most useful in developing late-season N application algorithms. PMID:26540057

Active-Optical Sensors Using Red NDVI Compared to Red Edge NDVI for Prediction of Corn Grain Yield in North Dakota, U.S.A.

PubMed

Sharma, Lakesh K; Bu, Honggang; Denton, Anne; Franzen, David W

2015-11-02

Active-optical sensor readings from an N non-limiting area standard established within a farm field are used to predict yield in the standard. Lower yield predictions from sensor readings obtained from other parts of the field outside of the N non-limiting standard area indicate a need for supplemental N. Active-optical sensor algorithms for predicting corn (Zea mays, L.) yield to direct in-season nitrogen (N) fertilization in corn utilize red NDVI (normalized differential vegetative index). Use of red edge NDVI might improve corn yield prediction at later growth stages when corn leaves cover the inter-row space resulting in "saturation" of red NDVI readings. The purpose of this study was to determine whether the use of red edge NDVI in two active-optical sensors (GreenSeeker™ and Holland Scientific Crop Circle™) improved corn yield prediction. Nitrogen rate experiments were established at 15 sites in North Dakota (ND). Sensor readings were conducted at V6 and V12 corn. Red NDVI and red edge NDVI were similar in the relationship of readings with yield at V6. At V12, the red edge NDVI was superior to the red NDVI in most comparisons, indicating that it would be most useful in developing late-season N application algorithms.

Mass production of silicon pore optics for ATHENA

NASA Astrophysics Data System (ADS)

Wille, Eric; Bavdaz, Marcos; Collon, Maximilien

2016-07-01

Silicon Pore Optics (SPO) provide high angular resolution with low effective area density as required for the Advanced Telescope for High Energy Astrophysics (Athena). The x-ray telescope consists of several hundreds of SPO mirror modules. During the development of the process steps of the SPO technology, specific requirements of a future mass production have been considered right from the beginning. The manufacturing methods heavily utilise off-the-shelf equipment from the semiconductor industry, robotic automation and parallel processing. This allows to upscale the present production flow in a cost effective way, to produce hundreds of mirror modules per year. Considering manufacturing predictions based on the current technology status, we present an analysis of the time and resources required for the Athena flight programme. This includes the full production process starting with Si wafers up to the integration of the mirror modules. We present the times required for the individual process steps and identify the equipment required to produce two mirror modules per day. A preliminary timeline for building and commissioning the required infrastructure, and for flight model production of about 1000 mirror modules, is presented.

The light up and early evolution of high redshift Supermassive Black Holes

NASA Astrophysics Data System (ADS)

Comastri, Andrea; Brusa, Marcella; Aird, James; Lanzuisi, Giorgio

2016-07-01

The known AGN population at z > 6 is made by luminous optical QSO hosting Supermassive Black Holes (M > 10 ^{9}solar masses), likely to represent the tip of the iceberg of the luminosity and mass function. According to theoretical models for structure formation, Massive Black Holes (M _{BH} 10^{4-7} solar masses) are predicted to be abundant in the early Universe (z > 6). The majority of these lower luminosity objects are expected to be obscured and severely underepresented in current optical near-infrared surveys. The detection of such a population would provide unique constraints on the Massive Black Holes formation mechanism and subsequent growth and is within the capabilities of deep and large area ATHENA surveys. After a summary of the state of the art of present deep XMM and Chandra surveys, at z >3-6 also mentioning the expectations for the forthcoming eROSITA all sky survey; I will present the observational strategy of future multi-cone ATHENA Wide Field Imager (WFI) surveys and the expected breakthroughs in the determination of the luminosity function and its evolution at high (> 4) and very high (>6) redshifts.

Characterizing shock waves in hydrogel using high speed imaging and a fiber-optic probe hydrophone

NASA Astrophysics Data System (ADS)

Anderson, Phillip A.; Betney, M. R.; Doyle, H. W.; Tully, B.; Ventikos, Y.; Hawker, N. A.; Roy, Ronald A.

2017-05-01

The impact of a stainless steel disk-shaped projectile launched by a single-stage light gas gun is used to generate planar shock waves with amplitudes on the order of 102MPa in a hydrogel target material. These shock waves are characterized using ultra-high-speed imaging as well as a fiber-optic probe hydrophone. Although the hydrogel equation of state (EOS) is unknown, the combination of these measurements with conservation of mass and momentum allows us to calculate pressure. It is also shown that although the hydrogel behaves similarly to water, the use of a water EOS underpredicts pressure amplitudes in the hydrogel by ˜10 % at the shock front. Further, the water EOS predicts pressures approximately 2% higher than those determined by conservation laws for a given value of the shock velocity. Shot to shot repeatability is controlled to within 10%, with the shock speed and pressure increasing as a function of the velocity of the projectile at impact. Thus the projectile velocity may be used as an adequate predictor of shock conditions in future work with a restricted suite of diagnostics.

Climate logging with a new rapid optical technique at siple dome

USGS Publications Warehouse

Bay, R.C.; Price, P.B.; Clow, G.D.; Gow, A.J.

2001-01-01

The dust logger design is based on a decade of experience in the use of light sources to measure optical properties of deep Antarctic ice. Light is emitted at the top of the instrument by side-directed LEDs, scattered or absorbed by dust in the ice surrounding the borehole, and collected in a downhole-pointing photomultiplier tube (PMT) a meter below. With this method the ice is sampled at ambient pressure in a much larger volume than is the case in a core study, and the entire length can be logged in one day. In ice in which scattering is dominated by bubbles, the absorption from dust impurities is perceived as a drop in signal, whereas in bubble-free ice the scattering from dust increases the light collected. We report on results obtained in Siple Dome Hole A in December 2000. The instrument measured increases in dust concentration extending over many meters during glacial maxima, as well as narrow spikes due to ??? 1 cm thick ash and dust bands of volcanic origin. Monte Carlo simulation is employed to clarify data analysis and predict the capabilities of future designs.

Installing the Future. Fiber Optics Program Readies Students for Lucrative Jobs.

ERIC Educational Resources Information Center

Serrano, Kenneth M.

1995-01-01

A fiber optics program at Somerset County Technical Institute (SCTI) prepares college students and trades workers for telecommunication's new wave of installation. The program was born of a partnership among an electricians' union, AT&T, and SCTI to meet the expected need for fiber optic technicians. (JOW)

Recent results and future plans for a 45 actuator adaptive x-ray optics experiment at the advanced light source

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

Brejnholt, Nicolai F., E-mail: brejnholt1@llnl.gov; Poyneer, Lisa A.; Hill, Randal M.

2016-07-27

We report on the current status of the Adaptive X-ray Optics project run by Lawrence Livermore National Laboratory (LLNL). LLNL is collaborating with the Advanced Light Source (ALS) to demonstrate a near real-time adaptive X-ray optic. To this end, a custom-built 45 cm long deformable mirror has been installed at ALS beamline 5.3.1 (end station 2) for a two-year period that started in September 2014. We will outline general aspects of the instrument, present results from a recent experimental campaign and touch on future plans for the project.

Polymorphic transition of tin under shock wave compression: Experimental results

NASA Astrophysics Data System (ADS)

Chauvin, C.; Petit, J.; Sinatti, F.

2012-08-01

In this work, the β-bct polymorphic transition in tin is investigated by means of plate impact experiments. The Sn target surface is observed in a partially released state obtained thanks to a transparent lithium fluoride (LiF) anvil. We report both measurements of interface velocity and temperature obtained using Photon Doppler Velocimetry and IR optical pyrometer on shock-loaded tin from 8 to 16 GPa. We show that the Mabire Model EOS associated to the SCG plasticity model provides an overall good estimate of the velocity profiles. However, depnding on the shock amplitude, its prediction of the temperature profile may be less satisfactory, hence underlining the need for future improvements in terms of phase transition kinetics description.

Vibrational spectroscopic and quantum chemical calculations of (E)-N-Carbamimidoyl-4-((naphthalen-1-yl-methylene)amino)benzene sulfonamide.

PubMed

Chandran, Asha; Varghese, Hema Tresa; Mary, Y Sheena; Panicker, C Yohannan; Manojkumar, T K; Van Alsenoy, Christian; Rajendran, G

2012-02-15

FT-IR and FT-Raman spectra of (E)-N-Carbamimidoyl-4-((naphthalen-1-yl-methylene)amino)benzene sulfonamide were recorded and analyzed. The vibrational wavenumbers were computing at various levels of theory. The data obtained from theoretical calculations are used to assign vibrational bands obtained experimentally. The results indicate that B3LYP method is able to provide satisfactory results for predicting vibrational frequencies and structural parameters. The calculated first hyperpolarizability is comparable with reported values of similar derivatives and is an attractive object for future studies of non-linear optics. The geometrical parameters of the title compound are in agreement with that of similar derivatives. Copyright © 2011 Elsevier B.V. All rights reserved.

Transistor Laser Optical NOR Gate for High Speed Optical Logic Processors

DTIC Science & Technology

2017-03-20

proposes an optical bistable latch can be built with two universal photonic NOR gate circuits, which are implemented by the three-port tunneling ... Tunneling Junction Transistor Laser (TJ-TL); Optical NOR Gate. Introduction To fulfill the future national security and intelligence needs in this...two-terminal diode lasers. Three-Port Transistor Laser – an Integration of Quantum-Wells into Heterojunction Bipolar Transistor Different than

A MIMO-Inspired Rapidly Switchable Photonic Interconnect Architecture (Postprint)

DTIC Science & Technology

2009-07-01

capabilities of future systems. Highspeed optical processing has been looked to as a means for eliminating this interconnect bottleneck. Presented...here are the results of a study for a novel optical (integrated photonic) processor which would allow for a high-speed, secure means for arbitrarily...regarded as a Multiple Input Multiple Output (MIMO) architecture. 15. SUBJECT TERMS Free-space optical interconnects, Optical Phased Arrays, High-Speed

Recent progress in graphene-material-based optical sensors.

PubMed

Deng, Xianghua; Tang, Hao; Jiang, Jianhui

2014-11-01

Graphene material has been widely used for optical sensors owing to its excellent properties, including high-energy transfer efficiency, large surface area, and great biocompatibility. Different analytes such as nucleic acids, proteins, and small molecules can be detected by graphene-material-based optical sensors. This review provides a comprehensive discussion of graphene-material-based optical sensors focusing on detection mechanisms and biosensor designs. Challenges and future perspectives for graphene-material-based optical sensors are also presented.

Alternative designs for space x-ray telescopes

NASA Astrophysics Data System (ADS)

Hudec, R.; Pína, L.; Maršíková, Veronika; Černá, Daniela; Inneman, A.; Tichý, V.

2017-11-01

The X-ray optics is a key element of space X-ray telescopes, as well as other X-ray imaging instruments. The grazing incidence X-ray lenses represent the important class of X-ray optics. Most of grazing incidence (reflective) X-ray imaging systems used in astronomy but also in other (laboratory) applications are based on the Wolter 1 (or modified) arrangement. But there are also other designs and configurations proposed, used and considered for future applications both in space and in laboratory. The Kirkpatrick-Baez (K-B) lenses as well as various types of Lobster-Eye optics and MCP/Micropore optics serve as an example. Analogously to Wolter lenses, the X-rays are mostly reflected twice in these systems to create focal images. Various future projects in X-ray astronomy and astrophysics will require large segments with multiple thin shells or foils. The large Kirkpatrick-Baez modules, as well as the large Lobster-Eye X-ray telescope modules in Schmidt arrangement may serve as examples. All related space projects will require high quality and light segmented shells (bent or flat foils) with high X-ray reflectivity and excellent mechanical stability. The Multi Foil Optics (MFO) approach represent a promising alternative for both LE and K-B X-ray optical modules. Several types of reflecting substrates may be considered for these applications, with emphasis on thin float glass sheets and, more recently, high quality silicon wafers. This confirms the importance of non-Wolter X-ray optics designs for the future. The alternative designs require novel reflective substrates which are also discussed in the paper.

Characteristics of color optical shutter with dye-doped polymer network liquid crystal.

PubMed

Lee, G H; Hwang, K Y; Jang, J E; Jin, Y W; Lee, S Y; Jung, J E

2011-03-01

The optical properties and the theoretical prediction of color optical shutter with dye-doped polymer network liquid crystal (PNLC) were investigated. The view-angle dependence of reflectance according to the bias conditions showed distinctive characteristics, which could be explained from the effects of dye absorption and path length. It was also shown that the thickness dependence of reflectance was strongly influenced by the light-scattering coefficient. Our experimental results matched up well with the theoretical prediction based on the light scattering of liquid crystals in polymer network and the absorption of dichroic dye. This work indicates potential to improve the optical device using dye-doped liquid crystal-polymer composite.

RF Fiber Optic Link.

DTIC Science & Technology

1984-06-01

index fiber has approximately 400 MHz/km. In the near future improvements in the material dispersion of glass may allow single mode bandwidths well above...attractive for K-band *(12 GI~z) TYRO, high definition TV channels, as well as the SBS (Satellite Business Systems) operation, in the near future.1...34Noise and Distortion Characteristics of Semi-Conductor Lasers in Optical Fiber Communication Systems", IEEE J. Quantum Electron., vol. QE-18, pp. 543-555

Optical-model abrasion cross sections for high-energy heavy ions

NASA Technical Reports Server (NTRS)

Townsend, L. W.

1981-01-01

Within the context of eikonal scattering theory, a generalized optical model potential approximation to the nucleus-nucleus multiple scattering series is used in an abrasion-ablation collision model to predict abrasion cross sections for relativistic projectile heavy ions. Unlike the optical limit of Glauber theory, which cannot be used for very light nuclei, the abrasion formalism is valid for any projectile target combination at any incident kinetic energy for which eikonal scattering theory can be utilized. Results are compared with experimental results and predictions from Glauber theory.

Vector optical activity in the Weyl semimetal TaAs

DOE PAGES

Norman, M. R.

2015-12-15

Here, it is shown that the Weyl semimetal TaAs can have a significant polar vector contribution to its optical activity. This is quantified by ab initio calculations of the resonant x-ray diffraction at the Ta L1 edge. For the Bragg vector (400), this polar vector contribution to the circular intensity differential between left and right polarized x-rays is predicted to be comparable to that arising from linear dichroism. Implications this result has in regards to optical effects predicted for topological Weyl semimetals are discussed.

Predicting threshold and location of laser damage on optical surfaces

DOEpatents

Siekhaus, W.

1985-02-04

Disclosed is an apparatus useful in the prediction of the damage threshold of various optical devices, the location of weak spots on such devices and the location, identification, and elimination of optical surface impurities. The apparatus comprises a focused and pulsed laser, a photo electric detector/imaging means, and a timer. The weak spots emit photoelectrons when subjected to laser intensities that are less than the intensity actually required to produce the damage. The weak spots may be eliminated by sustained exposure to the laser beam.

Satellite Survivability Module

NASA Astrophysics Data System (ADS)

Buehler, P.; Smith, J.

The Satellite Survivability Module (SSM) is an end-to-end, physics-based, performance prediction model for directed energy engagement of orbiting spacecraft. SSM was created as an add-on module for the Satellite Tool Kit (STK). Two engagement types are currently supported: laser engagement of the focal plane array of an imaging spacecraft; and Radio Frequency (RF) engagement of spacecraft components. This paper will focus on the laser engagement scenario, the process by which it is defined, and how we use this tool to support a future laser threat detection system experiment. For a laser engagement, the user creates a spacecraft, defines its optical system, adds any protection techniques used by the optical system, introduces a laser threat, and then defines the atmosphere through which the laser will pass. SSM models the laser engagement and its impact on the spacecraft's optical system using four impact levels: degradation, saturation, damage, and destruction. Protection techniques, if employed, will mitigate engagement effects. SSM currently supports two laser protection techniques. SSM allows the user to create and implement a variety of "what if" scenarios. Satellites can be placed in a variety of orbits. Threats can be placed anywhere on the Earth or, for version 2.0, on other satellites. Satellites and threats can be mixed and matched to examine possibilities. Protection techniques for a particular spacecraft can be turned on or off individually; and can be arranged in any order to simulate more complicated protection schemes. Results can be displayed as 2-D or 3-D visualizations, or as textual reports. A new report feature available in version 2.0 will allow laser effects data to be displayed dynamically during scenario execution. In order to test SSM capabilities, the Ball team used SSM to model several engagement scenarios for our future laser threat detection system experiment. Actual test sites, along with actual laser, optics, and detector characteristics were entered into SSM to determine what effects we can expect to see, and to what extent. We concluded that SSM results are accurate when compared to actual field test results. The work is currently funded by the Air Force Research Laboratory, Space Vehicles directorate at Kirtland AFB, New Mexico, under contract number FA9453-06-C-0371.

Status of Free-Space Optical Communications at JPL

NASA Technical Reports Server (NTRS)

Hemmati, H.

2000-01-01

Optical communications is a rapidly developing technology applicable to future NASA and commercial space missions that desire a communications terminal that provides a higher data rate with lower mass and power.

Fiber Optics: A Bright Future.

ERIC Educational Resources Information Center

Rice, James, Jr.

1980-01-01

Presents an overview of the impact of fiber optics on telecommunications and its application to information processing and library services, including information retrieval, news services, remote transmission of library services, and library networking. (RAA)

Prediction of future uniform milk prices in Florida federal milk marketing order 6 from milk futures markets.

PubMed

De Vries, A; Feleke, S

2008-12-01

This study assessed the accuracy of 3 methods that predict the uniform milk price in Federal Milk Marketing Order 6 (Florida). Predictions were made for 1 to 12 mo into the future. Data were from January 2003 to May 2007. The CURRENT method assumed that future uniform milk prices were equal to the last announced uniform milk price. The F+BASIS and F+UTIL methods were based on the milk futures markets because the futures prices reflect the market's expectation of the class III and class IV cash prices that are announced monthly by USDA. The F+BASIS method added an exponentially weighted moving average of the difference between the class III cash price and the historical uniform milk price (also known as basis) to the class III futures price. The F+UTIL method used the class III and class IV futures prices, the most recently announced butter price, and historical utilizations to predict the skim milk prices, butterfat prices, and utilizations in all 4 classes. Predictions of future utilizations were made with a Holt-Winters smoothing method. Federal Milk Marketing Order 6 had high class I utilization (85 +/- 4.8%). Mean and standard deviation of the class III and class IV cash prices were $13.39 +/- 2.40/cwt (1 cwt = 45.36 kg) and $12.06 +/- 1.80/cwt, respectively. The actual uniform price in Tampa, Florida, was $16.62 +/- 2.16/cwt. The basis was $3.23 +/- 1.23/cwt. The F+BASIS and F+UTIL predictions were generally too low during the period considered because the class III cash prices were greater than the corresponding class III futures prices. For the 1- to 6-mo-ahead predictions, the root of the mean squared prediction errors from the F+BASIS method were $1.12, $1.20, $1.55, $1.91, $2.16, and $2.34/cwt, respectively. The root of the mean squared prediction errors ranged from $2.50 to $2.73/cwt for predictions up to 12 mo ahead. Results from the F+UTIL method were similar. The accuracies of the F+BASIS and F+UTIL methods for all 12 fore-cast horizons were not significantly different. Application of the modified Mariano-Diebold tests showed that no method included all the information contained in the other methods. In conclusion, both F+BASIS and F+UTIL methods tended to more accurately predict the future uniform milk prices than the CURRENT method, but prediction errors could be substantial even a few months into the future. The majority of the prediction error was caused by the inefficiency of the futures markets to predict the class III cash prices.

Materials requirements for optical processing and computing devices

NASA Technical Reports Server (NTRS)

Tanguay, A. R., Jr.

1985-01-01

Devices for optical processing and computing systems are discussed, with emphasis on the materials requirements imposed by functional constraints. Generalized optical processing and computing systems are described in order to identify principal categories of requisite components for complete system implementation. Three principal device categories are selected for analysis in some detail: spatial light modulators, volume holographic optical elements, and bistable optical devices. The implications for optical processing and computing systems of the materials requirements identified for these device categories are described, and directions for future research are proposed.

Experimental and theoretical investigations on the validity of the geometrical optics model for calculating the stability of optical traps.

PubMed

Schut, T C; Hesselink, G; de Grooth, B G; Greve, J

1991-01-01

We have developed a computer program based on the geometrical optics approach proposed by Roosen to calculate the forces on dielectric spheres in focused laser beams. We have explicitly taken into account the polarization of the laser light and thd divergence of the laser beam. The model can be used to evaluate the stability of optical traps in a variety of different optical configurations. Our calculations explain the experimental observation by Ashkin that a stable single-beam optical trap, without the help of the gravitation force, can be obtained with a strongly divergent laser beam. Our calculations also predict a different trap stability in the directions orthogonal and parallel to the polarization direction of the incident light. Different experimental methods were used to test the predictions of the model for the gravity trap. A new method for measuring the radiation force along the beam axis in both the stable and instable regions is presented. Measurements of the radiation force on polystyrene spheres with diameters of 7.5 and 32 microns in a TEM00-mode laser beam showed a good qualitative correlation with the predictions and a slight quantitative difference. The validity of the geometrical approximations involved in the model will be discussed for spheres of different sizes and refractive indices.

Camera Optics.

ERIC Educational Resources Information Center

Ruiz, Michael J.

1982-01-01

The camera presents an excellent way to illustrate principles of geometrical optics. Basic camera optics of the single-lens reflex camera are discussed, including interchangeable lenses and accessories available to most owners. Several experiments are described and results compared with theoretical predictions or manufacturer specifications.…

Space-Based Optical Communications with CubeSats

NASA Technical Reports Server (NTRS)

Ebert, Monica L.; Nguyen, Anh Ngoc; Frost, Chad

2017-01-01

Optical communication systems use lasers to encode and transmit data with higher speed and density than traditional radio frequency (RF)-based communications. Smaller antennas, lower power requirements, and increased spectrum availability enable optical communications to be integrated into CubeSats more easily than radios, enabling afford-able communications solutions for future NASA missions.

Ferroelectric Tungsten Bronze Bulk Crystals and Epitaxial Thin Films for Electro-Optic Device Applications

DTIC Science & Technology

1984-02-01

110) film orientations. Electro - optic measurements on SBN:60 single crystals have shown a high value for r51 of 80 x 10 to the minus 12th power m/v...showing morphotropic boundary conditions with enhanced dielectric properties. Both systems look promising for future electro - optic development.

XRCF Testing Capabilities

NASA Technical Reports Server (NTRS)

Reily, Cary; Kegely, Jeff; Burdine, Robert (Technical Monitor)

2001-01-01

The Space Optics Manufacturing Technology Center's X-ray Calibration Facility has been recently modified to test Next Generation Space Telescope (NGST) developmental mirrors at cryogenic temperatures (35 degrees Kelvin) while maintaining capability for performance testing of x-ray optics and detectors. The facility's current cryo-optical testing capability and potential modifications for future support of NGST will be presented.

The Potential Role of Drexon LaserCards in Optical Publishing.

ERIC Educational Resources Information Center

Schwerin, Julie B.

1985-01-01

Describes Drexon LaserCard (credit card size format holding two megabytes of digital data that can be recorded at factory or by information distributors) as a viable option to rotating optical media for distribution of computer software, technical manuals, periodicals, and other document applications, and projects its future in optical publishing.…

Using the ISS as a testbed to prepare for the next generation of space-based telescopes

NASA Astrophysics Data System (ADS)

Postman, Marc; Sparks, William B.; Liu, Fengchuan; Ess, Kim; Green, Joseph; Carpenter, Kenneth G.; Thronson, Harley; Goullioud, Renaud

2012-09-01

The infrastructure available on the ISS provides a unique opportunity to develop the technologies necessary to assemble large space telescopes. Assembling telescopes in space is a game-changing approach to space astronomy. Using the ISS as a testbed enables a concentration of resources on reducing the technical risks associated with integrating the technologies, such as laser metrology and wavefront sensing and control (WFS&C), with the robotic assembly of major components including very light-weight primary and secondary mirrors and the alignment of the optical elements to a diffraction-limited optical system in space. The capability to assemble the optical system and remove and replace components via the existing ISS robotic systems such as the Special Purpose Dexterous Manipulator (SPDM), or by the ISS Flight Crew, allows for future experimentation as well as repair if necessary. In 2015, first light will be obtained by the Optical Testbed and Integration on ISS eXperiment (OpTIIX), a small 1.5-meter optical telescope assembled on the ISS. The primary objectives of OpTIIX include demonstrating telescope assembly technologies and end-to-end optical system technologies that will advance future large optical telescopes.

The status of optical communications at NASA/JPL

NASA Technical Reports Server (NTRS)

Hemmati, H.

2001-01-01

Future NASA and commercial space missions will require communications terminals to provide higher data rate with lower mass and power. Optical communications is a rapidly developing technology in response to this demand.

The Electronic and Electro-Optic Future of III-V Semiconductor Compounds.

DTIC Science & Technology

1978-12-01

An assessment of material development of III-V compounds for electro - optic , microwave and millimeter wave technology is presented. Questions concerning material selection, needs and processing is addressed. (Author)

Optical system design, analysis, and production; Proceedings of the Meeting, Geneva, Switzerland, April 19-22, 1983

NASA Astrophysics Data System (ADS)

Rogers, P. J.; Fischer, R. E.

1983-01-01

Topics considered include: optical system requirements, analysis, and system engineering; optical system design using microcomputers and minicomputers; optical design theory and computer programs; optical design methods and computer programs; optical design methods and philosophy; unconventional optical design; diffractive and gradient index optical system design; optical production and system integration; and optical systems engineering. Particular attention is given to: stray light control as an integral part of optical design; current and future directions of lens design software; thin-film technology in the design and production of optical systems; aspherical lenses in optical scanning systems; the application of volume phase holograms to avionic displays; the effect of lens defects on thermal imager performance; and a wide angle zoom for the Space Shuttle.

Hybrid Ground Station Technology for RF and Optical Communication Links

NASA Technical Reports Server (NTRS)

Davarian, Faramaz; Hoppe, D.; Charles, J.; Vilnrotter, V.; Sehic, A.; Hanson, T.; Gam, E.

2012-01-01

To support future enhancements of NASA's deep space and planetary communications and tracking services, the Jet Propulsion Laboratory is developing a hybrid ground station that will be capable of simultaneously supporting RF and optical communications. The main reason for adding optical links to the existing RF links is to significantly increase the capacity of deep space communications in support of future solar system exploration. It is envisioned that a mission employing an optical link will also use an RF link for telemetry and emergency purposes, hence the need for a hybrid ground station. A hybrid station may also reduce operations cost by requiring fewer staff than would be required to operate two stations. A number of approaches and techniques have been examined. The most promising ones have been prototyped for field examination and validation.

Empirical algorithms for ocean optics parameters

NASA Astrophysics Data System (ADS)

Smart, Jeffrey H.

2007-06-01

As part of the Worldwide Ocean Optics Database (WOOD) Project, The Johns Hopkins University Applied Physics Laboratory has developed and evaluated a variety of empirical models that can predict ocean optical properties, such as profiles of the beam attenuation coefficient computed from profiles of the diffuse attenuation coefficient. In this paper, we briefly summarize published empirical optical algorithms and assess their accuracy for estimating derived profiles. We also provide new algorithms and discuss their applicability for deriving optical profiles based on data collected from a variety of locations, including the Yellow Sea, the Sea of Japan, and the North Atlantic Ocean. We show that the scattering coefficient (b) can be computed from the beam attenuation coefficient (c) to about 10% accuracy. The availability of such relatively accurate predictions is important in the many situations where the set of data is incomplete.

Received optical power calculations for optical communications link performance analysis

NASA Technical Reports Server (NTRS)

Marshall, W. K.; Burk, B. D.

1986-01-01

The factors affecting optical communication link performance differ substantially from those at microwave frequencies, due to the drastically differing technologies, modulation formats, and effects of quantum noise in optical communications. In addition detailed design control table calculations for optical systems are less well developed than corresponding microwave system techniques, reflecting the relatively less mature state of development of optical communications. Described below are detailed calculations of received optical signal and background power in optical communication systems, with emphasis on analytic models for accurately predicting transmitter and receiver system losses.

Feasibility assessment of optical technologies for reliable high capacity feeder links

NASA Astrophysics Data System (ADS)

Witternigg, Norbert; Schönhuber, Michael; Leitgeb, Erich; Plank, Thomas

2013-08-01

Space telecom scenarios like data relay satellite and broadband/broadcast service providers require reliable feeder links with high bandwidth/data rate for the communication between ground station and satellite. Free space optical communication (FSOC) is an attractive alternative to microwave links, improving performance by offering abundant bandwidth at small apertures of the optical terminals. At the same time Near-Earth communication by FSOC avoids interference with other services and is free of regulatory issues. The drawback however is the impairment by the laser propagation through the atmosphere at optical wavelengths. Also to be considered are questions of eye safety for ground personnel and aviation. In this paper we assess the user requirements for typical space telecom scenarios and compare these requirements with solutions using optical data links through the atmosphere. We suggest a site diversity scheme with a number of ground stations and a switching scheme using two optical terminals on-board the satellite. Considering the technology trade-offs between four different optical wavelengths we recommend the future use of 1.5 μm laser technology and calculate a link budget for an atmospheric condition of light haze on the optical path. By comparing link budgets we show an outlook to the future potential use of 10 μm laser technology.

Fiber Optic Sensors for Health Monitoring of Morphing Aircraft

NASA Technical Reports Server (NTRS)

Brown, Timothy; Wood, Karen; Childers, Brooks; Cano, Roberto; Jensen, Brian; Rogowski, Robert

2001-01-01

Fiber optic sensors are being developed for health monitoring of future aircraft. Aircraft health monitoring involves the use of strain, temperature, vibration and chemical sensors. These sensors will measure load and vibration signatures that will be used to infer structural integrity. Sine the aircraft morphing program assumes that future aircraft will be aerodynamically reconfigurable there is also a requirement for pressure, flow and shape sensors. In some cases a single fiber may be used for measuring several different parameters. The objective of the current program is to develop techniques for using optical fibers to monitor composite cure in real time during manufacture and to monitor in-service structural integrity of the composite structure. Graphite-epoxy panels were fabricated with integrated optical fibers of various types. The panels were mechanically and thermally tested to evaluate composite strength and sensor durability. Finally the performance of the fiber optic sensors was determined. Experimental results are presented evaluating the performance of embedded and surface mounted optical fibers for measuring strain, temperature and chemical composition. The performance of the fiber optic sensors was determined by direct comparison with results from more conventional instrumentation. The facilities for fabricating optical fiber and associated sensors and methods of demodulating Bragg gratings for strain measurement will be described.

Active optics - The NTT and the future

NASA Astrophysics Data System (ADS)

Wilson, R. N.; Franza, F.; Giordano, P.; Noethe, L.; Tarenghi, M.

1988-09-01

An account is given of the essential design features and advantages of the ESO's NTT system optics, constituting an active telescope in which the optical correction process exhibited in histograms can be performed at will, on-line, so that the intrinsic quality of the telescope can be fully realized. This technology allows the relaxation of low spatial frequency (long-wave) manufacturing tolerances, and accomplishes automatic maintenance with respect to errors due to optics' maladjustment. Linearity, convergence, and orthogonality laws are used by the optical correction process algorithm.

Visible and near-infrared bulk optical properties of raw milk.

PubMed

Aernouts, B; Van Beers, R; Watté, R; Huybrechts, T; Lammertyn, J; Saeys, W

2015-10-01

The implementation of optical sensor technology to monitor the milk quality on dairy farms and milk processing plants would support the early detection of altering production processes. Basic visible and near-infrared spectroscopy is already widely used to measure the composition of agricultural and food products. However, to obtain maximal performance, the design of such optical sensors should be optimized with regard to the optical properties of the samples to be measured. Therefore, the aim of this study was to determine the visible and near-infrared bulk absorption coefficient, bulk scattering coefficient, and scattering anisotropy spectra for a diverse set of raw milk samples originating from individual cow milkings, representing the milk variability present on dairy farms. Accordingly, this database of bulk optical properties can be used in future simulation studies to efficiently optimize and validate the design of an optical milk quality sensor. In a next step of the current study, the relation between the obtained bulk optical properties and milk quality properties was analyzed in detail. The bulk absorption coefficient spectra were found to mainly contain information on the water, fat, and casein content, whereas the bulk scattering coefficient spectra were found to be primarily influenced by the quantity and the size of the fat globules. Moreover, a strong positive correlation (r ≥ 0.975) was found between the fat content in raw milk and the measured bulk scattering coefficients in the 1,300 to 1,400 nm wavelength range. Relative to the bulk scattering coefficient, the variability on the scattering anisotropy factor was found to be limited. This is because the milk scattering anisotropy is nearly independent of the fat globule and casein micelle quantity, while it is mainly determined by the size of the fat globules. As this study shows high correlations between the sample's bulk optical properties and the milk composition and fat globule size, a sensor that allows for robust separation between the absorption and scattering properties would enable accurate prediction of the raw milk quality parameters. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Monte Carlo Simulation of Plumes Spectral Emission

DTIC Science & Technology

2005-06-07

ERIM experimental data for hot cell radiance has been performed. It has been shown that NASA standard infrared optical model [3] provides good...Influence of different optical models on predicted numerical data on hot cell radiance for ERIM experimental conditions has been studied. 7...prediction (solid line) of the Hot cell radiance. NASA Standard Infrared Radiation model ; averaged rotational line structure (JLBL=0); spectral

Piezoelectric actuators for active optics

NASA Astrophysics Data System (ADS)

Le Letty, R.; Barillot, F.; Fabbro, H.; Guay, Ph.; Cadiergues, L.

2017-11-01

Piezoelectric actuators find their first applications in active space optics. The purpose of this paper is to describe the state of the art and some applications. Piezo actuators display attractive features for space applications, such as precise positioning, unlubricated, non magnetic and compact features, and low power consumption. However, piezo mechanisms cannot be considered separately from their driving and control electronic. Piezo actuators, such as Amplified Piezo Actuators or Parallel Pre-stressed Actuators, initially designed under CNES contracts, shall find their first space flight applications in optics on the PHARAO Laser bench: • fine pointing of the laser beams, • laser cavity tuning. Breadboard mechanisms based on piezo actuators have also been tested for refocusing purposes. Other applications includes the improvement of the CCD resolution through an oversampling technique, such as in the SOHO/LASCO instrument, fast optical shutter operation, optical filter in combination with a Fabry - Perot interferometer, such as in future LIDAR for earth observation. The first applications shall be described and an overview of the future potential applications shall be given.

Optical application of electrowetting

NASA Astrophysics Data System (ADS)

He, Mei; Peng, Runling; Chen, Jiabi

2017-02-01

Since electrowetting has been proposed, researchers began to apply eletrowetting into different fields, such as lab-on-chip systems, display technologies, printings and optics etc. This paper mainly introduced structure, theory and application of optical devices based on electrowetting. The optical devices include liquid optical prism, liquid optical lens and display. The paper introduced their principle, specific application and many advantages in optical applications. When they are applied to optical system, production and experiment, they can reduce mechanical moving parts, simplify the structure, operate easily, decrease manufacturing cost and energy consumption, improve working efficiency, and so on. We learn and research them in detail that will contribute to research and develop optical eletrowetting in the future.

First light of an external occulter testbed at flight Fresnel numbers

NASA Astrophysics Data System (ADS)

Kim, Yunjong; Sirbu, Dan; Hu, Mia; Kasdin, Jeremy; Vanderbei, Robert J.; Harness, Anthony; Shaklan, Stuart

2017-01-01

Many approaches have been suggested over the last couple of decades for imaging Earth-like planets. One of the main candidates for creating high-contrast for future Earth-like planets detection is an external occulter. The external occulter is a spacecraft flown along the line-of-sight of a space telescope to suppress starlight and enable high-contrast direct imaging of exoplanets. The occulter is typically tens of meters in diameter and the separation from the telescope is of the order of tens of thousands of kilometers. Optical testing of a full-scale external occulter on the ground is impossible because of the long separations. Therefore, laboratory verification of occulter designs is necessary to validate the optical models used to design and predict occulter performance. At Princeton, we have designed and built a testbed that allows verification of scaled occulter designs whose suppressed shadow is mathematically identical to that of space occulters. The goal of this experiment is to demonstrate a pupil plane suppression of better than 1e-9 with a corresponding image plane contrast of better than 1e-11. The occulter testbed uses a 77.2 m optical propagation distance to realize the flight Fresnel number of 14.5. The scaled mask is placed at 27.2 m from the artificial source and the camera is located 50.0 m from the scaled mask. We will use an etched silicon mask, manufactured by the Microdevices Lab(MDL) of the Jet Propulsion Laboratory(JPL), as the occulter. Based on conversations with MDL, we expect that 0.5 μm feature size is an achievable resolution in the mask manufacturing process and is therefore likely the indicator of the best possible performance. The occulter is illuminated by a diverging laser beam to reduce the aberrations from the optics before the occulter. Here, we present first light result of a sample design operating at a flight Fresnel number and the experimental setup of the testbed. We compare the experimental results with simulations that predict the ultimate contrast performance.

Comparison of modelling accuracy with and without exploiting automated optical monitoring information in predicting the treated wastewater quality.

PubMed

Tomperi, Jani; Leiviskä, Kauko

2018-06-01

Traditionally the modelling in an activated sludge process has been based on solely the process measurements, but as the interest to optically monitor wastewater samples to characterize the floc morphology has increased, in the recent years the results of image analyses have been more frequently utilized to predict the characteristics of wastewater. This study shows that the traditional process measurements or the automated optical monitoring variables by themselves are not capable of developing the best predictive models for the treated wastewater quality in a full-scale wastewater treatment plant, but utilizing these variables together the optimal models, which show the level and changes in the treated wastewater quality, are achieved. By this early warning, process operation can be optimized to avoid environmental damages and economic losses. The study also shows that specific optical monitoring variables are important in modelling a certain quality parameter, regardless of the other input variables available.

Prediction of apparent extinction for optical transmission through rain

NASA Astrophysics Data System (ADS)

Vasseur, H.; Gibbins, C. J.

1996-12-01

At optical wavelengths, geometrical optics holds that the extinction efficiency of raindrops is equal to two. This approximation yields a wavelength-independent extinction coefficient that, however, can hardly be used to predict accurately rain extinction measured in optical transmissions. Actually, in addition to the extinct direct incoming light, a significant part of the power scattered by the rain particles reaches the receiver. This leads to a reduced apparent extinction that depends on both rain characteristics and link parameters. A simple method is proposed to evaluate this apparent extinction. It accounts for the additional scattered power that enters the receiver when one considers the forward-scattering pattern of the raindrops as well as the multiple-scattering effects using, respectively, the Fraunhofer diffraction and Twersky theory. It results in a direct analytical formula that enables a quick and accurate estimation of the rain apparent extinction and highlights the influence of the link parameters. Predictions of apparent extinction through rain are found in excellent agreement with measurements in the visible and IR regions.

Longitudinal evidence for anterograde trans-synaptic degeneration after optic neuritis

PubMed Central

Goodkin, Olivia; Altmann, Daniel R.; Jenkins, Thomas M.; Miszkiel, Katherine; Mirigliani, Alessia; Fini, Camilla; Gandini Wheeler-Kingshott, Claudia A. M.; Thompson, Alan J.; Ciccarelli, Olga; Toosy, Ahmed T.

2016-01-01

Abstract In multiple sclerosis, microstructural damage of normal-appearing brain tissue is an important feature of its pathology. Understanding these mechanisms is vital to help develop neuroprotective strategies. The visual pathway is a key model to study mechanisms of damage and recovery in demyelination. Anterograde trans-synaptic degeneration across the lateral geniculate nuclei has been suggested as a mechanism of tissue damage to explain optic radiation abnormalities seen in association with demyelinating disease and optic neuritis, although evidence for this has relied solely on cross-sectional studies. We therefore aimed to assess: (i) longitudinal changes in the diffusion properties of optic radiations after optic neuritis suggesting trans-synaptic degeneration; (ii) the predictive value of early optic nerve magnetic resonance imaging measures for late optic radiations changes; and (iii) the impact on visual outcome of both optic nerve and brain post-optic neuritis changes. Twenty-eight consecutive patients with acute optic neuritis and eight healthy controls were assessed visually (logMAR, colour vision, and Sloan 1.25%, 5%, 25%) and by magnetic resonance imaging, at baseline, 3, 6, and 12 months. Magnetic resonance imaging sequences performed (and metrics obtained) were: (i) optic nerve fluid-attenuated inversion-recovery (optic nerve cross-sectional area); (ii) optic nerve proton density fast spin-echo (optic nerve proton density-lesion length); (iii) optic nerve post-gadolinium T 1 -weighted (Gd-enhanced lesion length); and (iv) brain diffusion-weighted imaging (to derive optic radiation fractional anisotropy, radial diffusivity, and axial diffusivity). Mixed-effects and multivariate regression models were performed, adjusting for age, gender, and optic radiation lesion load. These identified changes over time and associations between early optic nerve measures and 1-year global optic radiation/clinical measures. The fractional anisotropy in patients’ optic radiations decreased ( P = 0.018) and radial diffusivity increased ( P = 0.002) over 1 year following optic neuritis, whereas optic radiation measures were unchanged in controls. Also, smaller cross-sectional areas of affected optic nerves at 3 months post-optic neuritis predicted lower fractional anisotropy and higher radial diffusivity at 1 year ( P = 0.007) in the optic radiations, whereas none of the inflammatory measures of the optic nerve predicted changes in optic radiations. Finally, greater Gd-enhanced lesion length at baseline and greater optic nerve proton density-lesion length at 1 year were associated with worse visual function at 1 year ( P = 0.034 for both). Neither the cross-sectional area of the affected optic nerve after optic neuritis nor the damage in optic radiations was associated with 1-year visual outcome. Our longitudinal study shows that, after optic neuritis, there is progressive damage to the optic radiations, greater in patients with early residual optic nerve atrophy, even after adjusting for optic radiation lesions. These findings provide evidence for trans-synaptic degeneration. PMID:26912640

Head & neck optical diagnostics: vision of the future of surgery

PubMed Central

Upile, Tahwinder; Jerjes, Waseem; Sterenborg, Henricus JCM; El-Naggar, Adel K; Sandison, Ann; Witjes, Max JH; Biel, Merrill A; Bigio, Irving; Wong, Brian JF; Gillenwater, Ann; MacRobert, Alexander J; Robinson, Dominic J; Betz, Christian S; Stepp, Herbert; Bolotine, Lina; McKenzie, Gordon; Mosse, Charles Alexander; Barr, Hugh; Chen, Zhongping; Berg, Kristian; D'Cruz, Anil K; Stone, Nicholas; Kendall, Catherine; Fisher, Sheila; Leunig, Andreas; Olivo, Malini; Richards-Kortum, Rebecca; Soo, Khee Chee; Bagnato, Vanderlei; Choo-Smith, Lin-Ping; Svanberg, Katarina; Tan, I Bing; Wilson, Brian C; Wolfsen, Herbert; Yodh, Arjun G; Hopper, Colin

2009-01-01

Review paper and Proceedings of the Inaugural Meeting of the Head and Neck Optical Diagnostics Society (HNODS) on March 14th 2009 at University College London. The aim of our research must be to provide breakthrough translational research which can be applied clinically in the immediate rather than the near future. We are fortunate that this is indeed a possibility and may fundamentally change current clinical and surgical practice to improve our patients' lives. PMID:19594907

Development, history, and future of automated cell counters.

PubMed

Green, Ralph; Wachsmann-Hogiu, Sebastian

2015-03-01

Modern automated hematology instruments use either optical methods (light scatter), impedance-based methods based on the Coulter principle (changes in electrical current induced by blood cells flowing through an electrically charged opening), or a combination of both optical and impedance-based methods. Progressive improvement in these instruments has allowed the enumeration and evaluation of blood cells with great accuracy, precision, and speed at very low cost. Future directions of hematology instrumentation include the addition of new parameters and the development of point-of-care instrumentation. In the future, in-vivo analysis of blood cells may allow noninvasive and near-continuous measurements. Copyright © 2015 Elsevier Inc. All rights reserved.

The Market for Optical Disk Products: A Review of Published Forecasts, 1980-1990.

ERIC Educational Resources Information Center

Saffady, William

1991-01-01

Examines the expectations and reality of optical disk market forecasts published between 1980 and 1990. A historical survey and review of these studies is presented, with general forecasts of all optical disk types included. It is concluded that unrealistic predictions may have contributed to a sluggish market for optical disks. (70 notes)…

Assessment of Spacecraft Operational Status Using Electro-Optical Predictive Techniques

DTIC Science & Technology

2010-09-01

panel appendages, may require enhanced preflight characterization processes to support monitoring by passive, remote, nonimaging optical sensors...observing and characterizing key spacecraft features. The simulation results are based on electro-optical signatures apparent to nonimaging sensors, along...and communication equipment, may require enhanced preflight characterization processes to support monitoring by passive, remote, nonimaging optical

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.

Optical design and tolerancing of an ophthalmological system

NASA Astrophysics Data System (ADS)

Sieber, Ingo; Martin, Thomas; Yi, Allen; Li, Likai; Rübenach, Olaf

2014-09-01

Tolerance analysis by means of simulation is an essential step in system integration. Tolerance analysis allows for predicting the performance of a system setup of real manufactured parts and for an estimation of the yield with respect to evaluation figures, such as performance requirements, systems specification or cost demands. Currently, optical freeform optics is gaining importance in optical systems design. The performance of freeform optics often strongly depends on the manufacturing accuracy of the surfaces. For this reason, a tolerance analysis with respect to the fabrication accuracy is of crucial importance. The characterization of form tolerances caused by the manufacturing process is based on the definition of straightness, flatness, roundness, and cylindricity. In case of freeform components, however, it is often impossible to define a form deviation by means of this standard classification. Hence, prediction of the impact of manufacturing tolerances on the optical performance is not possible by means of a conventional tolerance analysis. To carry out a tolerance analysis of the optical subsystem, including freeform optics, metrology data of the fabricated surfaces have to be integrated into the optical model. The focus of this article is on design for manufacturability of freeform optics with integrated alignment structures and on tolerance analysis of the optical subsystem based on the measured surface data of manufactured optical freeform components with respect to assembly and manufacturing tolerances. This approach will be reported here using an ophthalmological system as an example.

Integrated Modeling of Complex Optomechanical Systems

NASA Astrophysics Data System (ADS)

Andersen, Torben; Enmark, Anita

2011-09-01

Mathematical modeling and performance simulation are playing an increasing role in large, high-technology projects. There are two reasons; first, projects are now larger than they were before, and the high cost calls for detailed performance prediction before construction. Second, in particular for space-related designs, it is often difficult to test systems under realistic conditions beforehand, and mathematical modeling is then needed to verify in advance that a system will work as planned. Computers have become much more powerful, permitting calculations that were not possible before. At the same time mathematical tools have been further developed and found acceptance in the community. Particular progress has been made in the fields of structural mechanics, optics and control engineering, where new methods have gained importance over the last few decades. Also, methods for combining optical, structural and control system models into global models have found widespread use. Such combined models are usually called integrated models and were the subject of this symposium. The objective was to bring together people working in the fields of groundbased optical telescopes, ground-based radio telescopes, and space telescopes. We succeeded in doing so and had 39 interesting presentations and many fruitful discussions during coffee and lunch breaks and social arrangements. We are grateful that so many top ranked specialists found their way to Kiruna and we believe that these proceedings will prove valuable during much future work.

Investigation of magnetically smart films applied to correct the surface profile of light weight X-ray optics in two directions

NASA Astrophysics Data System (ADS)

Wang, Xiaoli; Yao, Youwei; Cao, Jian; Vaynman, Semyon; Graham, Michael E.; Liu, Tianchen; Ulmer, M. P.

2015-09-01

Our goal is to improve initially fabricated X-ray optics figures by applying a magnetic field to drive a magnetic smart material (MSM) coating on the non-reflecting side of the mirror. The consequent deformation of the surface should be three-dimensional. Here we will report on the results of working with a glass sample of 50x50x0.2 mm that has been coated with MSMs. The coated glass can be deformed in 3 dimensions and its surface profile was measured under our Zygo NewView white light interferometer (WLI). The driving magnetic field was produced via a pseudo-magnetic write head made up of two permanent magnet posts. The magnet posts were moved about the bottom of the glass sample with a 3-d computer controlled translation stage. The system allowed four degrees of freedom of motion, i.e., up and down, side to side, back and forth, and rotation of the posts (3.175 mm diameter) about the vertical axis to allow us to change the orientation of the magnetic field in the (horizontal) plane of the sample. We established a finite element analysis (FEA) model to predict deformations and compare with the observed results in order to guide the application of the magnetically controlled MSMs to improve the future X-ray optics figures.

The evolution of the X-ray afterglow emission of GW 170817/ GRB 170817A in XMM-Newton observations

NASA Astrophysics Data System (ADS)

D'Avanzo, P.; Campana, S.; Salafia, O. S.; Ghirlanda, G.; Ghisellini, G.; Melandri, A.; Bernardini, M. G.; Branchesi, M.; Chassande-Mottin, E.; Covino, S.; D'Elia, V.; Nava, L.; Salvaterra, R.; Tagliaferri, G.; Vergani, S. D.

2018-05-01

We report our observation of the short gamma-ray burst (GRB) GRB 170817A, associated to the binary neutron star merger gravitational wave (GW) event GW 170817, performed in the X-ray band with XMM-Newton 135 d after the event (on 29 December, 2017). We find evidence for a flattening of the X-ray light curve with respect to the previously observed brightening. This is also supported by a nearly simultaneous optical Hubble Space Telescope observation and successive X-ray Chandra and low-frequency radio observations recently reported in the literature. Since the optical-to-X-ray spectral slope did not change with respect to previous observations, we exclude that the change in the temporal evolution of the light curve is due to the passage of the cooling frequency: its origin must be geometric or dynamical. We interpret all the existing afterglow data with two models: i) a structured jet and ii) a jet-less isotropic fireball with some stratification in its radial velocity structure. Both models fit the data and predict that the radio flux must decrease simultaneously with the optical and X-ray emission, making it difficult to distinguish between them at the present stage. Polarimetric measurements and the rate of short GRB-GW associations in future LIGO/Virgo runs will be key to disentangle these two geometrically different scenarios.

Optical Manufacturing and Testing Requirements Identified by the NASA Science Instruments, Observatories and Sensor Systems Technology Assessment

NASA Technical Reports Server (NTRS)

Stahl, H. Philip; Barney, Rich; Bauman, Jill; Feinberg, Lee; Mcleese, Dan; Singh, Upendra

2011-01-01

In August 2010, the NASA Office of Chief Technologist (OCT) commissioned an assessment of 15 different technology areas of importance to the future of NASA. Technology assessment #8 (TA8) was Science Instruments, Observatories and Sensor Systems (SIOSS). SIOSS assess the needs for optical technology ranging from detectors to lasers, x-ray mirrors to microwave antenna, in-situ spectrographs for on-surface planetary sample characterization to large space telescopes. The needs assessment looked across the entirety of NASA and not just the Science Mission Directorate. This paper reviews the optical manufacturing and testing technologies identified by SIOSS which require development in order to enable future NASA high priority missions.

Fabrication and test of digital output interface devices for gas turbine electronic controls

NASA Technical Reports Server (NTRS)

Newirth, D. M.; Koenig, E. W.

1978-01-01

A program was conducted to develop an innovative digital output interface device, a digital effector with optical feedback of the fuel metering valve position, for future electronic controls for gas turbine engines. A digital effector (on-off solenoids driven directly by on-off signals from a digital electronic controller) with optical position feedback was fabricated, coupled with the fuel metering valve, and tested under simulated engine operating conditions. The testing indicated that a digital effector with optical position feedback is a suitable candidate, with proper development for future digital electronic gas turbine controls. The testing also identified several problem areas which would have to be overcome in a final production configuration.

Quantum properties of light emitted by dipole nano-laser

NASA Astrophysics Data System (ADS)

Ghannam, Talal

Recent technological advances allow entire optical systems to be lithographically implanted on small silicon chips. These systems include tiny semiconductor lasers that function as light sources for digital optical signals. Future advances will rely on even smaller components. At the theoretical limit of this process, the smallest lasers will have an active medium consisting of a single atom (natural or artificial). Several suggestions for how this can be accomplished have already been published, such as nano-lasers based on photonic crystals and nano wires. In particular, the "dipole nanolaser" consists of a single quantum dot functioning as the active medium. It is optically coupled to a metal nanoparticles that form a resonant cavity. Laser light is generated from the near-field optical signal. The proposed work is a theoretical exploration of the nature of the resulting laser light. The dynamics of the system will be studied and relevant time scales described. These will form the basis for a set of operator equations describing the quantum properties of the emitted light. The dynamics will be studied in both density matrix and quantum Langevin formulations, with attention directed to noise sources. The equations will be linearized and solved using standard techniques. The result of the study will be a set of predicted noise spectra describing the statistics of the emitted light. The goal will be to identify the major noise contributions and suggest methods for suppressing them. This will be done by studying the probability of getting squeezed light from the nanoparticle for the certain scheme of parameters.

Sub-microradian pointing for deep space optical telecommunications network

NASA Technical Reports Server (NTRS)

Ortiz, G.; Lee, S.; Alexander, J.

2001-01-01

This presentation will cover innovative hardware, algorithms, architectures, techniques and recent laboratory results that are applicable to all deep space optical communication links, such as the Mars Telecommunication Network to future interstellar missions.

Use of Optical Mapping in Bacterial Genome Finishing

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

Kumar, Dibyendu

2010-06-03

Dibyendu Kumar from the University of Florida discusses whole-genome optical mapping to help validate bacterial genome assemblies on June 3, 2010 at the "Sequencing, Finishing, Analysis in the Future" meeting in Santa Fe, NM.

Stunningly bright optical emission

NASA Astrophysics Data System (ADS)

Heinke, Craig O.

2017-12-01

The detection of bright, rapid optical pulsations from pulsar PSR J1023+0038 have provided a surprise for researchers working on neutron stars. This discovery poses more questions than it answers and will spur on future work and instrumentation.

Laser inscription of pseudorandom structures for microphotonic diffuser applications.

PubMed

Alqurashi, Tawfiq; Alhosani, Abdulla; Dauleh, Mahmoud; Yetisen, Ali K; Butt, Haider

2018-04-19

Optical diffusers provide a solution for a variety of applications requiring a Gaussian intensity distribution including imaging systems, biomedical optics, and aerospace. Advances in laser ablation processes have allowed the rapid production of efficient optical diffusers. Here, we demonstrate a novel technique to fabricate high-quality glass optical diffusers with cost-efficiency using a continuous CO2 laser. Surface relief pseudorandom microstructures were patterned on both sides of the glass substrates. A numerical simulation of the temperature distribution showed that the CO2 laser drills a 137 μm hole in the glass for every 2 ms of processing time. FFT simulation was utilized to design predictable optical diffusers. The pseudorandom microstructures were characterized by optical microscopy, Raman spectroscopy, and angle-resolved spectroscopy to assess their chemical properties, optical scattering, transmittance, and polarization response. Increasing laser exposure and the number of diffusing surfaces enhanced the diffusion and homogenized the incident light. The recorded speckle pattern showed high contrast with sharp bright spot free diffusion in the far field view range (250 mm). A model of glass surface peeling was also developed to prevent its occurrence during the fabrication process. The demonstrated method provides an economical approach in fabricating optical glass diffusers in a controlled and predictable manner. The produced optical diffusers have application in fibre optics, LED systems, and spotlights.

An Optical Receiver Post Processing System for the Integrated Radio and Optical Communications Software Defined Radio Test Bed

NASA Technical Reports Server (NTRS)

Nappier, Jennifer M.; Tokars, Roger P.; Wroblewski, Adam C.

2016-01-01

The Integrated Radio and Optical Communications (iROC) project at the National Aeronautics and Space Administrations (NASA) Glenn Research Center is investigating the feasibility of a hybrid radio frequency (RF) and optical communication system for future deep space missions. As a part of this investigation, a test bed for a radio frequency (RF) and optical software defined radio (SDR) has been built. Receivers and modems for the NASA deep space optical waveform are not commercially available so a custom ground optical receiver system has been built. This paper documents the ground optical receiver, which is used in order to test the RF and optical SDR in a free space optical communications link.

An Optical Receiver Post-Processing System for the Integrated Radio and Optical Communications Software Defined Radio Test Bed

NASA Technical Reports Server (NTRS)

Nappier, Jennifer M.; Tokars, Roger P.; Wroblewski, Adam C.

2016-01-01

The Integrated Radio and Optical Communications (iROC) project at the National Aeronautics and Space Administration's (NASA) Glenn Research Center is investigating the feasibility of a hybrid radio frequency (RF) and optical communication system for future deep space missions. As a part of this investigation, a test bed for a radio frequency (RF) and optical software defined radio (SDR) has been built. Receivers and modems for the NASA deep space optical waveform are not commercially available so a custom ground optical receiver system has been built. This paper documents the ground optical receiver, which is used in order to test the RF and optical SDR in a free space optical communications link.

Autofluorescence and diffuse reflectance patterns in cervical spectroscopy

NASA Astrophysics Data System (ADS)

Marin, Nena Maribel

Fluorescence and diffuse reflectance spectroscopy are two new optical technologies, which have shown promise to aid in the real time, non-invasive identification of cancers and precancers. Spectral patterns carry a fingerprint of scattering, absorption and fluorescence properties in tissue. Scattering, absorption and fluorescence in tissue are directly affected by biological features that are diagnostically significant, such as nuclear size, micro-vessel density, volume fraction of collagen fibers, tissue oxygenation and cell metabolism. Thus, analysis of spectral patterns can unlock a wealth of information directly related with the onset and progression of disease. Data from a Phase II clinical trial to assess the technical efficacy of fluorescence and diffuse reflectance spectroscopy acquired from 850 women at three clinical locations with two research grade optical devices is calibrated and analyzed. Tools to process and standardize spectra so that data from multiple spectrometers can be combined and analyzed are presented. Methodologies for calibration and quality assurance of optical systems are established to simplify design issues and ensure validity of data for future clinical trials. Empirically based algorithms, using multivariate statistical approaches are applied to spectra and evaluated as a clinical diagnostic tool. Physically based algorithms, using mathematical models of light propagation in tissue are presented. The presented mathematical model combines a diffusion theory in P3 approximation reflectance model and a 2-layer fluorescence model using exponential attenuation and diffusion theory. The resulting adjoint fluorescence and reflectance model extracts twelve optical properties characterizing fluorescence efficiency of cervical epithelium and stroma fluorophores, stromal hemoglobin and collagen absorption, oxygen saturation, and stromal scattering strength and shape. Validations with Monte Carlo simulations show that adjoint model extracted optical properties of the epithelium and the stroma can be estimated accurately. Adjoint model is applied to 926 clinical measurements from 503 patients. Mean values of extracted optical properties have demonstrated to characterize the biological changes associated with dysplastic progression. Finally, penalized logistic regression algorithms are applied to discriminate dysplastic stages in tissue based on extracted optical features. This work provides understandable and interpretable information regarding predictive and generalization ability of optical spectroscopy in neoplastic changes using a minimum subset of optical measurements. Ultimately these methodologies would facilitate the transfer of these optical technologies into clinical practice.

New perspectives on an old problem: The bending of light in Yang-Mills gravity

NASA Astrophysics Data System (ADS)

Cottrell, Kazuo Ota; Hsu, Jong-Ping

Yang-Mills gravity with electromagnetism predicts, in the geometric optics limit, a value for the deflection of light by the sun which agrees closely with the reanalysis of Eddington's 1919 optical measurements done in 1979. Einstein's General Theory of Relativity, on the other hand, agrees very closely with measurements of the deflection of electromagnetic waves made in the range of radio frequencies. Since both General Relativity and Yang-Mills gravity with electromagnetism in the geometric optics limit make predictions for the optical region which fall within experimental uncertainty, it becomes important to consider the possibility of the existence of a frequency dependence in the measurement results for the deflection of light, in order to determine which theory more closely describes nature...

Optical/thermal analysis methodology for a space-qualifiable RTP furnace

NASA Technical Reports Server (NTRS)

Bugby, D.; Dardarian, S.; Cole, E.

1993-01-01

A methodology to predict the coupled optical/thermal performance of a reflective cavity heating system was developed and a laboratory test to verify the method was carried out. The procedure was utilized to design a rapid thermal processing (RTP) furnace for the Robot-Operated Material Processing in Space (ROMPS) Program which is a planned STS HH-G canister experiment involving robotics and material processing in microgravity. The laboratory test employed a tungsten-halogen reflector/lamp to heat thin, p-type silicon wafers. Measurements instrumentation consisted of 5-mil Pt/Pt-Rh thermocouples and an optical pyrometer. The predicted results, utilizing an optical ray-tracing program and a lumped-capacitance thermal analyzer, showed good agreement with the measured data for temperatures exceeding 1300 C.

The cognitive bases of the development of past and future episodic cognition in preschoolers.

PubMed

Ünal, Gülten; Hohenberger, Annette

2017-10-01

The aim of this study was to use a minimalist framework to examine the joint development of past and future episodic cognition and their underlying cognitive abilities in 3- to 5-year-old Turkish preschoolers. Participants engaged in two main tasks, a what-where-when (www) task to measure episodic memory and a future prediction task to measure episodic future thinking. Three additional tasks were used for predicting children's performance in the two main tasks: a temporal language task, an executive function task, and a spatial working memory task. Results indicated that past and future episodic tasks were significantly correlated with each other even after controlling for age. Hierarchical multiple regressions showed that, after controlling for age, the www task was predicted by executive functions, possibly supporting binding of episodic information and by linguistic abilities. The future prediction task was predicted by linguistic abilities alone, underlining the importance of language for episodic past and future thinking. Copyright © 2017 Elsevier Inc. All rights reserved.

Cloud Optical Depths and Liquid Water Paths at the NSA CART

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

Doran, J C.; Barnard, James C.; Zhong, Shiyuan

2000-03-14

Cloud optical depths have been measured using multifilter rotating shadowband radiometers (MFRSRs) at Barrow and Atqasuk, and liquid water paths have been measured at Barrow using a microwave radiometer (MWR) during the warm season (June-September) in 1999. Comparisons have been made between these quantities and the corresponding ones determined from the ECMWF GCM. Hour-by-hour comparisons of cloud optical depths show considerable scatter. The scatter is reduced, but is still substantial, when the averaging period is increased to ''daily'' averages, i.e., the time period each day over which the MFRSR can make measurements. This period varied between 18 hours in Junemore » and 6 hours in September. Preliminary results indicate that, for measured cloud optical depths less than approximately 25, the ECMWF has a low bias in its predictions, consistent with a low bias in predicted liquid water path. Based on a more limited set of data, the optical depths at Atqasuk were found to be generally lower than those at Barrow, a trend at least qualitatively captured by the ECMWF model. Analyses to identify the cause of the biases and the considerable scatter in the predictions are continuing.« less

Tunable Laser Development for In-Flight Fiber Optic Based Structural Health Monitoring Systems

NASA Technical Reports Server (NTRS)

Richards, Lance; Parker, Allen; Chan, Patrick

2013-01-01

Briefing based on tunable laser development for in flight fiber optic based structural health monitoring systems. The objective of this task is to investigate, develop, and demonstrate a low-cost swept lasing light source for NASA DFRC's fiber optics sensing system (FOSS) to perform structural health monitoring on current and future aerospace vehicles.

Solid state electro-optic color filter and iris

NASA Technical Reports Server (NTRS)

1974-01-01

Test results obtained have confirmed the practicality of the solid state electro-optic filters as an optical control element in a television system. Neutral-density control range in excess of 1000:1 has been obtained on sample filters. Test results, measurements in a complete camera system, discussions of problem areas, analytical comparisons, and recommendations for future investigations are included.

Flight-Like Optical Reference Cavity for GRACE Follow-On Laser Frequency Stabilization

NASA Technical Reports Server (NTRS)

Folkner, W. M.; deVine, G.; Klipstein, W. M.; McKenzie, K.; Spero, R.; Thompson, R.; Yu, N.; Stephens, M.; Leitch, J.; Pierce, R.;

Thermal Damage Analysis in Biological Tissues Under Optical Irradiation: Application to the Skin

NASA Astrophysics Data System (ADS)

Fanjul-Vélez, Félix; Ortega-Quijano, Noé; Solana-Quirós, José Ramón; Arce-Diego, José Luis

2009-07-01

The use of optical sources in medical praxis is increasing nowadays. In this study, different approaches using thermo-optical principles that allow us to predict thermal damage in irradiated tissues are analyzed. Optical propagation is studied by means of the radiation transport theory (RTT) equation, solved via a Monte Carlo analysis. Data obtained are included in a bio-heat equation, solved via a numerical finite difference approach. Optothermal properties are considered for the model to be accurate and reliable. Thermal distribution is calculated as a function of optical source parameters, mainly optical irradiance, wavelength and exposition time. Two thermal damage models, the cumulative equivalent minutes (CEM) 43 °C approach and the Arrhenius analysis, are used. The former is appropriate when dealing with dosimetry considerations at constant temperature. The latter is adequate to predict thermal damage with arbitrary temperature time dependence. Both models are applied and compared for the particular application of skin thermotherapy irradiation.

Advanced optical instruments technology

NASA Technical Reports Server (NTRS)

Shao, Mike; Chrisp, Michael; Cheng, Li-Jen; Eng, Sverre; Glavich, Thomas; Goad, Larry; Jones, Bill; Kaarat, Philip; Nein, Max; Robinson, William

1992-01-01

The science objectives for proposed NASA missions for the next decades push the state of the art in sensitivity and spatial resolution over a wide range of wavelengths, including the x-ray to the submillimeter. While some of the proposed missions are larger and more sensitive versions of familiar concepts, such as the next generation space telescope, others use concepts, common on the Earth, but new to space, such as optical interferometry, in order to provide spatial resolutions impossible with other concepts. However, despite their architecture, the performance of all of the proposed missions depends critically on the back-end instruments that process the collected energy to produce scientifically interesting outputs. The Advanced Optical Instruments Technology panel was chartered with defining technology development plans that would best improve optical instrument performance for future astrophysics missions. At this workshop the optical instrument was defined as the set of optical components that reimage the light from the telescope onto the detectors to provide information about the spatial, spectral, and polarization properties of the light. This definition was used to distinguish the optical instrument technology issues from those associated with the telescope, which were covered by a separate panel. The panel identified several areas for optical component technology development: diffraction gratings; tunable filters; interferometric beam combiners; optical materials; and fiber optics. The panel also determined that stray light suppression instruments, such as coronagraphs and nulling interferometers, were in need of general development to support future astrophysics needs.

Advanced optical instruments technology

NASA Astrophysics Data System (ADS)

Shao, Mike; Chrisp, Michael; Cheng, Li-Jen; Eng, Sverre; Glavich, Thomas; Goad, Larry; Jones, Bill; Kaarat, Philip; Nein, Max; Robinson, William

1992-08-01

The science objectives for proposed NASA missions for the next decades push the state of the art in sensitivity and spatial resolution over a wide range of wavelengths, including the x-ray to the submillimeter. While some of the proposed missions are larger and more sensitive versions of familiar concepts, such as the next generation space telescope, others use concepts, common on the Earth, but new to space, such as optical interferometry, in order to provide spatial resolutions impossible with other concepts. However, despite their architecture, the performance of all of the proposed missions depends critically on the back-end instruments that process the collected energy to produce scientifically interesting outputs. The Advanced Optical Instruments Technology panel was chartered with defining technology development plans that would best improve optical instrument performance for future astrophysics missions. At this workshop the optical instrument was defined as the set of optical components that reimage the light from the telescope onto the detectors to provide information about the spatial, spectral, and polarization properties of the light. This definition was used to distinguish the optical instrument technology issues from those associated with the telescope, which were covered by a separate panel. The panel identified several areas for optical component technology development: diffraction gratings; tunable filters; interferometric beam combiners; optical materials; and fiber optics. The panel also determined that stray light suppression instruments, such as coronagraphs and nulling interferometers, were in need of general development to support future astrophysics needs.

An Overview of the Tropospheric Aerosol Radiative Forcing Observational Experiment

NASA Technical Reports Server (NTRS)

Russell, P. B.; Chan, K. Roland (Technical Monitor)

1997-01-01

Aerosol effects on atmospheric radiation are a leading source of uncertainty in predicting future climate. As a result, the International Global Atmospheric Chemistry Program has established a Focus on Atmospheric Aerosols (IGAC/FAA) and endorsed a series of aerosol field campaigns. TARFOX, the second in the IGAC/FAA series, was designed to reduce this uncertainty by measuring aerosol properties and effects in the US eastern seaboard, where one of the world's major plumes of industrial haze moves from the continent over the Atlantic Ocean. TARFOX's objectives are to: 1. Make simultaneous measurements of: (a) aerosol effects on radiation fields, and (b) the chemical, physical, and optical properties of the aerosols causing those effects. 2. Perform a variety of closure studies by using overdetermined data sets to test the mutual consistency of measurements and calculations of a wide range of aerosol properties and effects. 3. Use the results of the closure studies to assess and reduce uncertainties in estimates of aerosol radiative forcing, as well as to guide future field programs. An important subset of the closure studies is tests and improvements of algorithms used to derive aerosol properties and radiative effects from satellite measurements. The TARFOX Intensive Field Period (IFP) was conducted July 10-31, 1996. It included coordinated measurements from four satellites (GOES-8, NOAA-14, ERS-2, LANDSAT), four aircraft (ER-2, C-130, C-131, and a modified Cessna), land sites, and ships. A variety of aerosol conditions was sampled, ranging from relatively clean behind frontal passages to moderately polluted with aerosol optical depths exceeding 0.5 at mid-visible wavelengths. The latter conditions included separate incidents of enhancements caused primarily by anthropogenic sources and another incident of enhancement apparently influenced by recent fog processing. Spatial gradients of aerosol optical thickness were sampled to aid in isolating aerosol effects from other radiative effects and to more tightly constrain closure tests, including those of satellite retrievals. This talk gives an overview of TARFOX goals, rationale, methods, and initial key findings.

The future of time and frequency dissemination

NASA Astrophysics Data System (ADS)

Levine, Judah

1994-05-01

I will try to extrapolate the changes in the dissemination of time and frequency information that have taken place during the last 25 years to predict the future developments both in the methods of disseminating time and frequency and in the kinds of customers we will be asked to serve. Two important developments are likely to play pivotal roles in driving the evolution of dissemination. The first is the commercial availability of very high quality clocks -- devices whose performance may eventually rival that of the current generation of primary frequency standards. The widespread use of these devices may blur the traditional distinction between client and server, and may replace it with a more symmetrical interchange of data among peers. The second is the increasing demand for digital time and frequency information driven by the increasing sophistication of everything from traffic lights to electric power meters. The needs of these individual users may not tax the state of the art of primary frequency standards in principle, but their large numbers and wide geographical distribution present a technological challenge that is difficult to meet at a reasonable price using existing methods. Some of these problems may be solved (or at least addressed) using developments in communications and consumer electronics such as the increasing use of fiber-optic telephone circuits and the increasing bandwidth and sophistication of the cable network used to transmit television pictures. To be useful, these advances in hardware must stimulate parallel advances in software algorithms and methods. These advances are more difficult to predict with great confidence, but the developments of the last few years will be examined to provide some indications of the future.

The future of time and frequency dissemination

NASA Technical Reports Server (NTRS)

Levine, Judah

1994-01-01

I will try to extrapolate the changes in the dissemination of time and frequency information that have taken place during the last 25 years to predict the future developments both in the methods of disseminating time and frequency and in the kinds of customers we will be asked to serve. Two important developments are likely to play pivotal roles in driving the evolution of dissemination. The first is the commercial availability of very high quality clocks -- devices whose performance may eventually rival that of the current generation of primary frequency standards. The widespread use of these devices may blur the traditional distinction between client and server, and may replace it with a more symmetrical interchange of data among peers. The second is the increasing demand for digital time and frequency information driven by the increasing sophistication of everything from traffic lights to electric power meters. The needs of these individual users may not tax the state of the art of primary frequency standards in principle, but their large numbers and wide geographical distribution present a technological challenge that is difficult to meet at a reasonable price using existing methods. Some of these problems may be solved (or at least addressed) using developments in communications and consumer electronics such as the increasing use of fiber-optic telephone circuits and the increasing bandwidth and sophistication of the cable network used to transmit television pictures. To be useful, these advances in hardware must stimulate parallel advances in software algorithms and methods. These advances are more difficult to predict with great confidence, but the developments of the last few years will be examined to provide some indications of the future.

Theory of Interactions of Intense Light with Nonlinear, Inhomogeneous, and Periodic Structures and Its Applications to Optical Bistability, Optic Gyroscopes, Nonlinear Spectroscopy, Radiation Protection, X-Ray Emission, and Related Fields.

DTIC Science & Technology

1987-10-01

bistable interaction of an electromagnetic wave with the simplest microscopic physical object. Most recently, consistent with this prediction , the hysteresis...1985, p. 17) credited both the experimental observation and the theoretical prediction as very important discoveries. London-based journal "Nature...order processes of this kind was also predicted , which was described as higher-order cyclo- -6- Raman effect whereby w, - W2 = nfl, where n is an

Direct hot slumping of thin glass foils for future generation x-ray telescopes: current state of the art and future outlooks

NASA Astrophysics Data System (ADS)

Salmaso, B.; Basso, S.; Brizzolari, C.; Civitani, M.; Ghigo, M.; Pareschi, G.; Spiga, D.; Tagliaferri, G.; Vecchi, G.

2017-11-01

To significantly improve the performances of the current X-ray observatories, the next generation of X-ray telescopes has to be characterized by a large effective area (Aeff { 2 m2 at 1 keV) and angular resolution better than 5 arcsec. The large dimension implied by these requirements forces the use of a modular approach, splitting the optics into segments. Moreover, lightweight materials, such as glass, have to be selected for the segmented optics in order to maintain a manageable weight for the optics. Since 2009 we are developing a direct hot slumping technique assisted by pressure, in which the glass optical surface is in contact with the mould and a pressure is applied in order to force the glass to copy the mould shape. A cold slumping step is used then to integrate the mirror segments into the final Wolter-I configuration. We present the state of the art of our hot slumping technology, comparing the results obtained with different glass types and mould materials. We also provide an overview of the possibilities of this technology also in view of future developments.

Characterization of the Performance of Sapphire Optical Fiber in Intense Radiation Fields, when Subjected to Very High Temperatures

NASA Astrophysics Data System (ADS)

Petrie, Christian M.

The U.S. Department of Energy is interested in extending optically-based instrumentation from non-extreme environments to extremely high temperature radiation environments for the purposes of developing in-pile instrumentation. The development of in-pile instrumentation would help support the ultimate goal of understanding the behavior and predicting the performance of nuclear fuel systems at a microstructural level. Single crystal sapphire optical fibers are a promising candidate for in-pile instrumentation due to the high melting temperature and radiation hardness of sapphire. In order to extend sapphire fiber-based optical instrumentation to high temperature radiation environments, the ability of sapphire fibers to adequately transmit light in such an environment must first be demonstrated. Broadband optical transmission measurements of sapphire optical fibers were made in-situ as the sapphire fibers were heated and/or irradiated. The damage processes in sapphire fibers were also modeled from the primary knock-on event from energetic neutrons to the resulting damage cascade in order to predict the formation of stable defects that ultimately determine the resulting change in optical properties. Sapphire optical fibers were shown to withstand temperatures as high as 1300 °C with minimal increases in optical attenuation. A broad absorption band was observed to grow over time without reaching a dynamic equilibrium when the sapphire fiber was heated at temperatures of 1400 °C and above. The growth of this absorption band limits the use of sapphire optical fibers, at least in air, to temperatures of 1300 °C and below. Irradiation of sapphire fibers with gamma rays caused saturation of a defect center located below 500 nm, and extending as far as ~1000 nm, with little effect on the transmission at 1300 and 1550 nm. Increasing temperature during gamma irradiation generally reduced the added attenuation. Reactor irradiation of sapphire fibers caused an initial rapid increase in attenuation, followed by a linear increase with continued irradiation time at constant reactor power. The linear increases were a result of displacement damage, and the rate of increase was proportional to the neutron flux. The transmission of sapphire fibers at 1300 and 1550 nm in a reactor radiation environment would ultimately be limited by the growth of low wavelength defect centers, whose tails extend into the near infrared. A model was proposed for the reactor radiation-induced attenuation that involves three previously reported color centers. The model accounts for gamma radiation-induced ionization of pre-existing defects, generation of new defects via displacement damage, and conversion between defect centers via ionization and charge recombination. Heated reactor irradiation experiments showed that the rate of increase of the added attenuation during constant power reactor irradiation monotonically decreases with increasing temperature up to 1000 °C, with the most significant decrease occurring between 300 and 600 °C. Testing of sapphire fiber-based sensors under irradiation at high temperatures is recommended as future work, along with advanced life irradiation testing, for example in the Advanced Test Reactor or the High Flux Isotope Reactor.

Diffractive-optical correlators: chances to make optical image preprocessing as intelligent as human vision

NASA Astrophysics Data System (ADS)

Lauinger, Norbert

2004-10-01

The human eye is a good model for the engineering of optical correlators. Three prominent intelligent functionalities in human vision could in the near future become realized by a new diffractive-optical hardware design of optical imaging sensors: (1) Illuminant-adaptive RGB-based color Vision, (2) Monocular 3D Vision based on RGB data processing, (3) Patchwise fourier-optical Object-Classification and Identification. The hardware design of the human eye has specific diffractive-optical elements (DOE's) in aperture and in image space and seems to execute the three jobs at -- or not far behind -- the loci of the images of objects.

Pricing Software and Information on CD-ROM.

ERIC Educational Resources Information Center

Gibbins, Patrick

1987-01-01

Examines the relationships between purchases of optical data disk products, publishers, and software suppliers. The discussion covers current pricing strategies for optical data disk software and information products, and possible future developments in marketing and pricing. (CLB)

Engineered materials for all-optical helicity-dependent magnetic switching

NASA Astrophysics Data System (ADS)

Mangin, S.; Gottwald, M.; Lambert, C.-H.; Steil, D.; Uhlíř, V.; Pang, L.; Hehn, M.; Alebrand, S.; Cinchetti, M.; Malinowski, G.; Fainman, Y.; Aeschlimann, M.; Fullerton, E. E.

2014-03-01

The possibility of manipulating magnetic systems without applied magnetic fields have attracted growing attention over the past fifteen years. The low-power manipulation of the magnetization, preferably at ultrashort timescales, has become a fundamental challenge with implications for future magnetic information memory and storage technologies. Here we explore the optical manipulation of the magnetization in engineered magnetic materials. We demonstrate that all-optical helicity-dependent switching (AO-HDS) can be observed not only in selected rare earth-transition metal (RE-TM) alloy films but also in a much broader variety of materials, including RE-TM alloys, multilayers and heterostructures. We further show that RE-free Co-Ir-based synthetic ferrimagnetic heterostructures designed to mimic the magnetic properties of RE-TM alloys also exhibit AO-HDS. These results challenge present theories of AO-HDS and provide a pathway to engineering materials for future applications based on all-optical control of magnetic order.

Feasibility of utilizing Cherenkov Telescope Array gamma-ray telescopes as free-space optical communication ground stations.

PubMed

Carrasco-Casado, Alberto; Vilera, Mariafernanda; Vergaz, Ricardo; Cabrero, Juan Francisco

2013-04-10

The signals that will be received on Earth from deep-space probes in future implementations of free-space optical communication will be extremely weak, and new ground stations will have to be developed in order to support these links. This paper addresses the feasibility of using the technology developed in the gamma-ray telescopes that will make up the Cherenkov Telescope Array (CTA) observatory in the implementation of a new kind of ground station. Among the main advantages that these telescopes provide are the much larger apertures needed to overcome the power limitation that ground-based gamma-ray astronomy and optical communication both have. Also, the large number of big telescopes that will be built for CTA will make it possible to reduce costs by economy-scale production, enabling optical communications in the large telescopes that will be needed for future deep-space links.

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

Khalili, Farid; Danilishin, Stefan; Mueller-Ebhardt, Helge

We consider enhancing the sensitivity of future gravitational-wave detectors by using double optical spring. When the power, detuning and bandwidth of the two carriers are chosen appropriately, the effect of the double optical spring can be described as a 'negative inertia', which cancels the positive inertia of the test masses and thus increases their response to gravitational waves. This allows us to surpass the free-mass standard quantum limit (SQL) over a broad frequency band, through signal amplification, rather than noise cancellation, which has been the case for all broadband SQL-beating schemes so far considered for gravitational-wave detectors. The merit ofmore » such signal amplification schemes lies in the fact that they are less susceptible to optical losses than noise-cancellation schemes. We show that it is feasible to demonstrate such an effect with the Gingin High Optical Power Test Facility, and it can eventually be implemented in future advanced GW detectors.« less

Optical Characterization of Window Materials for Aerospace Applications

NASA Technical Reports Server (NTRS)

Tedjojuwono, Ken K.; Clark, Natalie; Humphreys, William M., Jr.

2013-01-01

An optical metrology laboratory has been developed to characterize the optical properties of optical window materials to be used for aerospace applications. Several optical measurement systems have been selected and developed to measure spectral transmittance, haze, clarity, birefringence, striae, wavefront quality, and wedge. In addition to silica based glasses, several optical lightweight polymer materials and transparent ceramics have been investigated in the laboratory. The measurement systems and selected empirical results for non-silica materials are described. These measurements will be used to form the basis of acceptance criteria for selection of window materials for future aerospace vehicle and habitat designs.

Multichannel demultiplexer/demodulator technologies for future satellite communication systems

NASA Technical Reports Server (NTRS)

Ivancic, William D.; Budinger, James M.; Staples, Edward J.; Abramovitz, Irwin; Courtois, Hector A.

1992-01-01

NASA-Lewis' Space Electronics Div. supports ongoing research in advanced satellite communication architectures, onboard processing, and technology development. Recent studies indicate that meshed VSAT (very small aperture terminal) satellite communication networks using FDMA (frequency division multiple access) uplinks and TDMA (time division multiplexed) downlinks are required to meet future communication needs. One of the critical advancements in such a satellite communication network is the multichannel demultiplexer/demodulator (MCDD). The progress is described which was made in MCDD development using either acousto-optical, optical, or digital technologies.

Modeling and prediction of relaxation of polar order in high-activity nonlinear optical polymers

NASA Astrophysics Data System (ADS)

Guenthner, Andrew J.; Lindsay, Geoffrey A.; Wright, Michael E.; Fallis, Stephen; Ashley, Paul R.; Sanghadasa, Mohan

2007-09-01

Mach-Zehnder optical modulators were fabricated using the CLD and FTC chromophores in polymer-on-silicon optical waveguides. Up to 17 months of oven-ageing stability are reported for the poled polymer films. Modulators containing an FTC-polyimide had the best over all aging performance. To model and extrapolate the ageing data, a relaxation correlation function attributed to A. K. Jonscher was compared to the well-established stretched exponential correlation function. Both models gave a good fit to the data. The Jonscher model predicted a slower relaxation rate in the out years. Analysis showed that collecting data for a longer period relative to the relaxation time was more important for generating useful predictions than the precision with which individual model parameters could be estimated. Thus from a practical standpoint, time-temperature superposition must be assumed in order to generate meaningful predictions. For this purpose, Arrhenius-type expressions were found to relate the model time constants to the ageing temperatures.

Advanced optical network architecture for integrated digital avionics

NASA Astrophysics Data System (ADS)

Morgan, D. Reed

1996-12-01

For the first time in the history of avionics, the network designer now has a choice in selecting the media that interconnects the sources and sinks of digital data on aircraft. Electrical designs are already giving way to photonics in application areas where the data rate times distance product is large or where special design requirements such as low weight or EMI considerations are critical. Future digital avionic architectures will increasingly favor the use of photonic interconnects as network data rates of one gigabit/second and higher are needed to support real-time operation of high-speed integrated digital processing. As the cost of optical network building blocks is reduced and as temperature-rugged laser sources are matured, metal interconnects will be forced to retreat to applications spanning shorter and shorter distances. Although the trend is already underway, the widespread use of digital optics will first occur at the system level, where gigabit/second, real-time interconnects between sensors, processors, mass memories and displays separated by a least of few meters will be required. The application of photonic interconnects for inter-printed wiring board signalling across the backplane will eventually find application for gigabit/second applications since signal degradation over copper traces occurs before one gigabit/second and 0.5 meters are reached. For the foreseeable future however, metal interconnects will continue to be used to interconnect devices on printed wiring boards since 5 gigabit/second signals can be sent over metal up to around 15 centimeters. Current-day applications of optical interconnects at the system level are described and a projection of how advanced optical interconnect technology will be driven by the use of high speed integrated digital processing on future aircraft is presented. The recommended advanced network for application in the 2010 time frame is a fiber-based system with a signalling speed of around 2-3 gigabits per second. This switch-based unified network will interconnect sensors, displays, mass memory and controls and displays to computer modules within the processing complex. The characteristics of required building blocks needed for the future are described. These building blocks include the fiber, an optical switch, a laser-based transceiver, blind-mate connectors and an optical backplane.

Epoxy and Silicone Optical Nanocomposites Filled with Grafted Nanoparticles

NASA Astrophysics Data System (ADS)

Tao, Peng

Polymer nanocomposites, as a technologically important class of materials, exhibit diverse functional properties, and are used for applications ranging from structural and biomedical to electronic and optical. The properties of polymer nanocomposites are determined, in part, by the chemical composition of the polymer matrix and the nanofillers. Their properties are also sensitive to the geometry and size of the nanofillers, and to spatial distribution of the fillers. Control of the nanoparticle size and dispersion within a given polymer provides opportunities to tailor and optimize the properties of nanocomposites for specific application. For optical applications such as encapsulation of light emitting diodes (LEDs), polymer nanocomposites filled with homogeneously dispersed nanoparticles would endow the polymer encapsulant with new functionality without sacrificing optical transparency. To this end, this thesis focuses on developing a simple and versatile approach towards the fabrication of epoxy and silicone transparent nanocomposites using matrix compatible chain-grafted nanoparticles as fillers, and studying the optical properties of the nanocomposites. The surface chemistry and grafted polymer chain design have been shown to play an important role in determining the dispersion state of the grafted nanoparticles and hence the final optical properties of the nanocomposites. To prepare transparent epoxy nanocomposites, poly (glycidyl methacrylate) (PGMA) chains were grafted onto the optical nanoparticle surfaces via a combined phosphate ligand exchange process and azide-alkyne "click" chemistry. The dispersion behavior of PGMA-grafted nanoparticles within the epoxy matrix was investigated by systematically varying the grafting density and grafted chain length. It was found that within the small molecular weight epoxy resins, the dispersion states are more sensitive to the grafting density than the molecular weight of grafted chains. With high grafting densities, the grafted PGMA brushes effectively screen the van der Waals attraction between the particles, and homogenous nanoparticle dispersions of grafted nanoparticles were obtained. Transparent high refractive index TiO2/epoxy thin film and bulk nancomposites were obtained by dispersing PGMA brushes-grafted TiO2 nanoparticles into a commercial epoxy matrix. The refractive index of the nanocomposites showed a linear dependence on the volume fraction of TiO2 nanoparticles and the optical transparency could be generally described by the Rayleigh scattering model. This powerful dispersing technique was further employed to make visibly transparent, UV/IR blocking ITO/epoxy nanocomposites which can be easily applied onto glass and plastic substrates as energy saving optical coating materials. To produce transparent silicone nanocomposites, we directly coupled phosphate-terminated PDMS chains onto the optical nanoparticle surface. It was observed that the mono-modal PDMS-grafted particles usually formed agglomerates within silicone matrices, whereas the bimodal PDMS-grafted particles were able to be individually dispersed even within high molecular weight matrices. Transparent high refractive index bulk TiO2/silicone nanocomposites were successfully prepared by filling with bimodal PDMS-grafted TiO2 nanoparticles. Furthermore, we used the PDMS-grafted TiO2/silicone nanocomposite as a model system to create a methodology to predict and control the dispersion behavior of grafted nanoparticles. The good agreement between experimental observation of dispersion of mono-modal and bimodal grafted particles and theoretical prediction would better guide future experiments and lead to predictability in polymer composite design. Finally, the bimodal grafted chain design was implemented in the preparation of transparent and luminescent CdSe/silicone nanocomposites with potential application as non-scattering light conversion materials for LEDs. The homogeneous dispersion of bimodal PDMS-grafted CdSe quantum dots not only minimizes the transparency loss due to scattering, but also benefits the uniformity and long-term stability of photoluminescence of the nanocomposites.

Toward a complete theory for predicting inclusive deuteron breakup away from stability

NASA Astrophysics Data System (ADS)

Potel, G.; Perdikakis, G.; Carlson, B. V.; Atkinson, M. C.; Dickhoff, W. H.; Escher, J. E.; Hussein, M. S.; Lei, J.; Li, W.; Macchiavelli, A. O.; Moro, A. M.; Nunes, F. M.; Pain, S. D.; Rotureau, J.

2017-09-01

We present an account of the current status of the theoretical treatment of inclusive ( d, p) reactions in the breakup-fusion formalism, pointing to some applications and making the connection with current experimental capabilities. Three independent implementations of the reaction formalism have been recently developed, making use of different numerical strategies. The codes also originally relied on two different but equivalent representations, namely the prior (Udagawa-Tamura, UT) and the post (Ichimura-Austern-Vincent, IAV) representations. The different implementations have been benchmarked for the first time, and then applied to the Ca isotopic chain. The neutron-Ca propagator is described in the Dispersive Optical Model (DOM) framework, and the interplay between elastic breakup (EB) and non-elastic breakup (NEB) is studied for three Ca isotopes at two different bombarding energies. The accuracy of the description of different reaction observables is assessed by comparing with experimental data of ( d, p) on 40,48Ca. We discuss the predictions of the model for the extreme case of an isotope (60Ca) currently unavailable experimentally, though possibly available in future facilities (nominally within production reach at FRIB). We explore the use of ( d, p) reactions as surrogates for (n,γ ) processes, by using the formalism to describe the compound nucleus formation in a (d,pγ ) reaction as a function of excitation energy, spin, and parity. The subsequent decay is then computed within a Hauser-Feshbach formalism. Comparisons between the (d,pγ ) and (n,γ ) induced gamma decay spectra are discussed to inform efforts to infer neutron captures from (d,pγ ) reactions. Finally, we identify areas of opportunity for future developments, and discuss a possible path toward a predictive reaction theory.

JUPITER’S PHASE VARIATIONS FROM CASSINI : A TESTBED FOR FUTURE DIRECT-IMAGING MISSIONS

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

Mayorga, L. C.; Jackiewicz, J.; Rages, K.

We present empirical phase curves of Jupiter from ∼0° to 140° as measured in multiple optical bandpasses by Cassini /Imaging Science Subsystem (ISS) during the Millennium flyby of Jupiter in late 2000 to early 2001. Phase curves are of interest for studying the energy balance of Jupiter and understanding the scattering behavior of the planet as an exoplanet analog. We find that Jupiter is significantly darker at partial phases than an idealized Lambertian planet by roughly 25% and is not well fit by Jupiter-like exoplanet atmospheric models across all wavelengths. We provide analytic fits to Jupiter’s phase function in severalmore » Cassini /ISS imaging filter bandpasses. In addition, these observations show that Jupiter’s color is more variable with phase angle than predicted by models. Therefore, the color of even a near Jupiter-twin planet observed at a partial phase cannot be assumed to be comparable to that of Jupiter at full phase. We discuss how the Wide-Field Infrared Survey Telescope and other future direct-imaging missions can enhance the study of cool giants.« less

Colorizing SENTINEL-1 SAR Images Using a Variational Autoencoder Conditioned on SENTINEL-2 Imagery

NASA Astrophysics Data System (ADS)

Schmitt, M.; Hughes, L. H.; Körner, M.; Zhu, X. X.

2018-05-01

In this paper, we have shown an approach for the automatic colorization of SAR backscatter images, which are usually provided in the form of single-channel gray-scale imagery. Using a deep generative model proposed for the purpose of photograph colorization and a Lab-space-based SAR-optical image fusion formulation, we are able to predict artificial color SAR images, which disclose much more information to the human interpreter than the original SAR data. Future work will aim at further adaption of the employed procedure to our special case of multi-sensor remote sensing imagery. Furthermore, we will investigate if the low-level representations learned intrinsically by the deep network can be used for SAR image interpretation in an end-to-end manner.

Gas trace detection with cavity enhanced absorption spectroscopy: a review of its process in the field

NASA Astrophysics Data System (ADS)

Liu, Siqi; Luo, Zhifu; Tan, Zhongqi; Long, Xingwu

2016-11-01

Cavity-enhanced absorption spectroscopy (CEAS) is a technology in which the intracavity absorption is deduced from the intensity of light transmitted by the high finesse optical cavity. Then the samples' parameters, such as their species, concentration and absorption cross section, would be detection. It was first proposed and demonstrated by Engeln R. [1] and O'Keefe[2] in 1998. This technology has extraordinary detection sensitivity, high resolution and good practicability, so it is used in many fields , such as clinical medicine, gas detection and basic physics research. In this paper, we focus on the use of gas trace detection, including the advance of CEAS over the past twenty years, the newest research progresses, and the prediction of this technology's development direction in the future.

Graphene levitation and orientation control using a magnetic field

NASA Astrophysics Data System (ADS)

Niu, Chao; Lin, Feng; Wang, Zhiming M.; Bao, Jiming; Hu, Jonathan

2018-01-01

This paper studies graphene levitation and orientation control using a magnetic field. The torques in all three spatial directions induced by diamagnetic forces are used to predict stable conditions for different shapes of millimeter-sized graphite plates. We find that graphite plates, in regular polygon shapes with an even number of sides, will be levitated in a stable manner above four interleaved permanent magnets. In addition, the orientation of micrometer-sized graphene flakes near a permanent magnet is studied in both air and liquid environments. Using these analyses, we are able to simulate optical transmission and reflection on a writing board and thereby reveal potential applications using this technology for display screens. Understanding the control of graphene flake orientation will lead to the discovery of future applications using graphene flakes.

Infrared studies of topological insulator systems

NASA Astrophysics Data System (ADS)

Post, Kirk; Chapler, Brian; Schafgans, Alex; Liu, Mengkun; Wu, Jih-Sheng; Richardella, Anthony; Lee, Joon Sue; Reijnders, Anjan; Lee, Yun Sang; He, Liang; Kou, Xufeng; Novak, Mario; Taskin, Alexey; Segawa, Kouji; Goldflam, Michael; Stinson, H. Theodore; Qi, Xiao Liang; Burch, Kenneth; Wang, Kang; Fogler, Michael; Samarth, Nitin; Ando, Yoichi; Basov, Dimitri

The theoretical prediction, and subsequent experimental realization, of topological insulator (TI) systems, has vaulted this new class of materials to the vanguard of condensed matter physics. Since their discovery, we have carried out a number of infrared studies on various TI systems, including Bi2Se3, Bi1-xSbx, and Bi2-xSbxTe3-ySey crystals as well as Bi2Se3 and (Bi,Sb)2Te3 thin films. A key element of these works is the revelation that the infrared response of Bi1-xSbx crystals and (Bi,Sb)2Te3 thin films possess a significant, or even dominant, component from the topologically protected surface states. I will review these works and discuss future prospects of measuring the surface state response through optical spectroscopy techniques

FSO and quality of service software prediction

NASA Astrophysics Data System (ADS)

Bouchet, O.; Marquis, T.; Chabane, M.; Alnaboulsi, M.; Sizun, H.

2005-08-01

Free-space optical (FSO) communication links constitute an alternative option to radio relay links and to optical cables facing growth needs in high-speed telecommunications (abundance of unregulated bandwidth, rapid installation, availability of low-cost optical components offering a high data rate, etc). Their operationalisation requires a good knowledge of the atmospheric effects which can negatively affect role propagation and the availability of the link, and thus to the quality of service (QoS). Better control of these phenomena will allow for the evaluation of system performance and thus assist with improving reliability. The aim of this paper is to compare the behavior of a FSO link located in south of France (Toulouse: with the following parameters: around 270 meters (0.2 mile) long, 34 Mbps data rate, 850 nm wavelength and PDH frame) with airport meteorological data. The second aim of the paper is to assess in-house FSO quality of service prediction software, through comparing simulations with the optical link data and the weather data. The analysis uses in-house software FSO quality of service prediction software ("FSO Prediction") developed by France Telecom Research & Development, which integrates news fog fading equations (compare to Kim & al.) and includes multiple effects (geometrical attenuation, atmospheric fading, rain, snow, scintillation and refraction attenuation due to atmospheric turbulence, optical mispointing attenuation). The FSO link field trial, intended to enable the demonstration and evaluation of these different effects, is described; and preliminary results of the field trial, from December 2004 to May 2005, are then presented.

Optical pulse response of a fibre ring resonator

NASA Astrophysics Data System (ADS)

Pandian, G. S.; Seraji, Faramarz E.

1991-06-01

This article presents the optical pulse response analysis of a fiber ring resonator. It is shown that several interesting functions, namely optical pulse generation, and equalization of fiber dispersion can be realized by using the resonator. The theory is presented in an easy to understand manner, by first considering the steady-state response. The results of the transient pulse response are explained in relation to the steady state results. The results related to optical pulse shaping will be of interest to the future when coherent optical pulse and switching circuits will become available.

Testing of Sapphire Optical Fiber and Sensors in Intense Radiation Fields When Subjected to Very High Temperatures

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

Blue, Thomas; Windl, Wolfgang

The primary objective of this project was to determine the optical attenuation and signal degradation of sapphire optical fibers & sensors (temperature & strain), in-situ, operating at temperatures up to 1500°C during reactor irradiation through experiments and modeling. The results will determine the feasibility of extending sapphire optical fiber-based instrumentation to extremely high temperature radiation environments. This research will pave the way for future testing of sapphire optical fibers and fiber-based sensors under conditions expected in advanced high temperature reactors.

Telecommunications Policy Research Conference. Future of the Telecommunications Network Section. Papers.

ERIC Educational Resources Information Center

Telecommunications Policy Research Conference, Inc., Washington, DC.

The paper for which an abstract is presented here, "Future Network Architectures" (Anthony Rutowski), discussed innovations in processing/switching and transmission technologies, including the development of new broadband optical transfer modes using label and position multiplexing techniques. It is suggested that future network…

Review and perspective: Sapphire optical fiber cladding development for harsh environment sensing

NASA Astrophysics Data System (ADS)

Chen, Hui; Buric, Michael; Ohodnicki, Paul R.; Nakano, Jinichiro; Liu, Bo; Chorpening, Benjamin T.

2018-03-01

The potential to use single-crystal sapphire optical fiber as an alternative to silica optical fibers for sensing in high-temperature, high-pressure, and chemically aggressive harsh environments has been recognized for several decades. A key technological barrier to the widespread deployment of harsh environment sensors constructed with sapphire optical fibers has been the lack of an optical cladding that is durable under these conditions. However, researchers have not yet succeeded in incorporating a high-temperature cladding process into the typical fabrication process for single-crystal sapphire fibers, which generally involves seed-initiated fiber growth from the molten oxide state. While a number of advances in fabrication of a cladding after fiber-growth have been made over the last four decades, none have successfully transitioned to a commercial manufacturing process. This paper reviews the various strategies and techniques for fabricating an optically clad sapphire fiber which have been proposed and explored in published research. The limitations of current approaches and future prospects for sapphire fiber cladding are discussed, including fabrication methods and materials. The aim is to provide an understanding of the past research into optical cladding of sapphire fibers and to assess possible material systems for future research on this challenging problem for harsh environment sensors.

Dust models post-Planck: constraining the far-infrared opacity of dust in the diffuse interstellar medium

NASA Astrophysics Data System (ADS)

Fanciullo, L.; Guillet, V.; Aniano, G.; Jones, A. P.; Ysard, N.; Miville-Deschênes, M.-A.; Boulanger, F.; Köhler, M.

2015-08-01

Aims: We compare the performance of several dust models in reproducing the dust spectral energy distribution (SED) per unit extinction in the diffuse interstellar medium (ISM). We use our results to constrain the variability of the optical properties of big grains in the diffuse ISM, as published by the Planck collaboration. Methods: We use two different techniques to compare the predictions of dust models to data from the Planck HFI, IRAS, and SDSS surveys. First, we fit the far-infrared emission spectrum to recover the dust extinction and the intensity of the interstellar radiation field (ISRF). Second, we infer the ISRF intensity from the total power emitted by dust per unit extinction, and then predict the emission spectrum. In both cases, we test the ability of the models to reproduce dust emission and extinction at the same time. Results: We identify two issues. Not all models can reproduce the average dust emission per unit extinction: there are differences of up to a factor ~2 between models, and the best accord between model and observation is obtained with the more emissive grains derived from recent laboratory data on silicates and amorphous carbons. All models fail to reproduce the variations in the emission per unit extinction if the only variable parameter is the ISRF intensity: this confirms that the optical properties of dust are indeed variable in the diffuse ISM. Conclusions: Diffuse ISM observations are consistent with a scenario where both ISRF intensity and dust optical properties vary. The ratio of the far-infrared opacity to the V band extinction cross-section presents variations of the order of ~20% (40-50% in extreme cases), while ISRF intensity varies by ~30% (~60% in extreme cases). This must be accounted for in future modelling. Appendices are available in electronic form at http://www.aanda.org

Infrared fiber optic probe evaluation of degenerative cartilage correlates to histological grading.

PubMed

Hanifi, Arash; Bi, Xiaohong; Yang, Xu; Kavukcuoglu, Beril; Lin, Ping Chang; DiCarlo, Edward; Spencer, Richard G; Bostrom, Mathias P G; Pleshko, Nancy

2012-12-01

Osteoarthritis (OA), a degenerative cartilage disease, results in alterations of the chemical and structural properties of tissue. Arthroscopic evaluation of full-depth tissue composition is limited and would require tissue harvesting, which is inappropriate in daily routine. Fourier transform infrared (FT-IR) spectroscopy is a modality based on molecular vibrations of matrix components that can be used in conjunction with fiber optics to acquire quantitative compositional data from the cartilage matrix. To develop a model based on infrared spectra of articular cartilage to predict the histological Mankin score as an indicator of tissue quality. Comparative laboratory study. Infrared fiber optic probe (IFOP) spectra were collected from nearly normal and more degraded regions of tibial plateau articular cartilage harvested during knee arthroplasty (N = 61). Each region was graded using a modified Mankin score. A multivariate partial least squares algorithm using second-derivative spectra was developed to predict the histological modified Mankin score. The partial least squares model derived from IFOP spectra predicted the modified Mankin score with a prediction error of approximately 1.4, which resulted in approximately 72% of the Mankin-scored tissues being predicted correctly and 96% being predicted within 1 grade of their true score. These data demonstrate that IFOP spectral parameters correlate with histological tissue grade and can be used to provide information on tissue composition. Infrared fiber optic probe studies have significant potential for the evaluation of cartilage tissue quality without the need for tissue harvest. Combined with arthroscopy, IFOP analysis could facilitate the definition of tissue margins in debridement procedures.

An optical profilometer for spatial characterization of three-dimensional surfaces

NASA Technical Reports Server (NTRS)

Kelly, W. L., IV; Burcher, E. E.; Skolaut, M. W., Jr.

1977-01-01

The design concept and system operation of an optical profilometer are discussed, and a preliminary evaluation of a breadboard system is presented to demonstrate the feasibility of the optical profilometer technique. Measurement results are presented for several test surfaces; and to illustrate a typical application, results are shown for a cleft palate cast used by dental surgeons. Finally, recommendations are made for future development of the optical profilometer technique for specific engineering or scientific applications.

Grazing Incidence Nickel Replicated Optics for Hard X-ray Telescopes

NASA Technical Reports Server (NTRS)

Peturzzo, J. J., III; Elsner, R. F.; Joy, M. K.; ODell, S. L.; Weisskopf, M. C.

1997-01-01

The requirements for future hard x-ray (up to 50 keV) telescopes are lightweight, high angular resolution optics with large collecting areas. Grazing incidence replicated optics are an excellent candidate for this, type of mission, providing better angular resolution, comparable area/unit mass, and simpler fabrication than multilayer-coated foils. Most importantly, the technology to fabricate the required optics currently exists. A comparison of several hard x-ray telescope designs will be presented.

Efficient optical cloud removal technique for earth observation based on MOEMs device

NASA Astrophysics Data System (ADS)

Zamkotsian, Frédéric; Lanzoni, Patrick; Liotard, Arnaud; Viard, Thierry; Noell, Wilfried

2017-11-01

In Earth Observation instruments, observation of scenes including bright sources leads to an important degradation of the recorded signal. We propose a new concept to remove dynamically the bright sources and then obtain a field of view with an optically enhanced Signal-to-Noise Ratio (SNR). Micro-Opto-Electro-Mechanical Systems (MOEMS) could be key components in future generation of space instruments. MOEMS-based programmable slit masks will permit the straylight control in future Earth Observation instruments. Experimental demonstration of this concept has been conducted on a dedicated bench. This successful first demonstration shows the high potential of this new concept in future spectro-imager for Earth Observation.

Overview and future direction for blackbody solar-pumped lasers

NASA Technical Reports Server (NTRS)

Deyoung, R. J.

1988-01-01

A review of solar-pumped blackbody lasers is given which addresses their present status and suggests future research directions. The blackbody laser concept is one system proposed to scale to multimegawatt power levels for space-to-space power transmissions for such applications as onboard spacecraft electrical or propulsion needs. Among the critical technical issues are the scalability to high powers and the laser wavelength which impacts the transmission optics size as well as the laser-to-electric converter at the receiver. Because present blackbody solar-pumped lasers will have laser wavelengths longer than 4 microns, simple photovoltaic converters cannot be used, and transmission optics will be large. Thus, future blackbody laser systems should emphasize near visible laser wavelengths.

AMTD - Advanced Mirror Technology Development in Mechanical Stability

NASA Technical Reports Server (NTRS)

Knight, J. Brent

2015-01-01

Analytical tools and processes are being developed at NASA Marshal Space Flight Center in support of the Advanced Mirror Technology Development (AMTD) project. One facet of optical performance is mechanical stability with respect to structural dynamics. Pertinent parameters are: (1) the spacecraft structural design, (2) the mechanical disturbances on-board the spacecraft (sources of vibratory/transient motion such as reaction wheels), (3) the vibration isolation systems (invariably required to meet future science needs), and (4) the dynamic characteristics of the optical system itself. With stability requirements of future large aperture space telescopes being in the lower Pico meter regime, it is paramount that all sources of mechanical excitation be considered in both feasibility studies and detailed analyses. The primary objective of this paper is to lay out a path to perform feasibility studies of future large aperture space telescope projects which require extreme stability. To get to that end, a high level overview of a structural dynamic analysis process to assess an integrated spacecraft and optical system is included.

Modeling a space-based quantum link that includes an adaptive optics system

NASA Astrophysics Data System (ADS)

Duchane, Alexander W.; Hodson, Douglas D.; Mailloux, Logan O.

2017-10-01

Quantum Key Distribution uses optical pulses to generate shared random bit strings between two locations. If a high percentage of the optical pulses are comprised of single photons, then the statistical nature of light and information theory can be used to generate secure shared random bit strings which can then be converted to keys for encryption systems. When these keys are incorporated along with symmetric encryption techniques such as a one-time pad, then this method of key generation and encryption is resistant to future advances in quantum computing which will significantly degrade the effectiveness of current asymmetric key sharing techniques. This research first reviews the transition of Quantum Key Distribution free-space experiments from the laboratory environment to field experiments, and finally, ongoing space experiments. Next, a propagation model for an optical pulse from low-earth orbit to ground and the effects of turbulence on the transmitted optical pulse is described. An Adaptive Optics system is modeled to correct for the aberrations caused by the atmosphere. The long-term point spread function of the completed low-earth orbit to ground optical system is explored in the results section. Finally, the impact of this optical system and its point spread function on an overall quantum key distribution system as well as the future work necessary to show this impact is described.

Micro-precision control/structure interaction technology for large optical space systems

NASA Technical Reports Server (NTRS)

Sirlin, Samuel W.; Laskin, Robert A.

1993-01-01

The CSI program at JPL is chartered to develop the structures and control technology needed for sub-micron level stabilization of future optical space systems. The extreme dimensional stability required for such systems derives from the need to maintain the alignment and figure of critical optical elements to a small fraction (typically 1/20th to 1/50th) of the wavelength of detected radiation. The wavelength is about 0.5 micron for visible light and 0.1 micron for ultra-violet light. This lambda/50 requirement is common to a broad class of optical systems including filled aperture telescopes (with monolithic or segmented primary mirrors), sparse aperture telescopes, and optical interferometers. The challenge for CSI arises when such systems become large, with spatially distributed optical elements mounted on a lightweight, flexible structure. In order to better understand the requirements for micro-precision CSI technology, a representative future optical system was identified and developed as an analytical testbed for CSI concepts and approaches. An optical interferometer was selected as a stressing example of the relevant mission class. The system that emerged was termed the Focus Mission Interferometer (FMI). This paper will describe the multi-layer control architecture used to address the FMI's nanometer level stabilization requirements. In addition the paper will discuss on-going and planned experimental work aimed at demonstrating that multi-layer CSI can work in practice in the relevant performance regime.

Tunable Laser Development for In-flight Fiber Optic Based Structural Health Monitoring Systems

NASA Technical Reports Server (NTRS)

Richards, Lance; Parker, Allen; Chan, Patrick

2014-01-01

The objective of this task is to investigate, develop, and demonstrate a low-cost swept lasing light source for NASA DFRC's fiber optics sensing system (FOSS) to perform structural health monitoring on current and future aerospace vehicles. This is the regular update of the Tunable Laser Development for In-flight Fiber Optic Based Structural Health Monitoring Systems website.

SPECKLE NOISE SUBTRACTION AND SUPPRESSION WITH ADAPTIVE OPTICS CORONAGRAPHIC IMAGING

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

Ren Deqing; Dou Jiangpei; Zhang Xi

2012-07-10

Future ground-based direct imaging of exoplanets depends critically on high-contrast coronagraph and wave-front manipulation. A coronagraph is designed to remove most of the unaberrated starlight. Because of the wave-front error, which is inherit from the atmospheric turbulence from ground observations, a coronagraph cannot deliver its theoretical performance, and speckle noise will limit the high-contrast imaging performance. Recently, extreme adaptive optics, which can deliver an extremely high Strehl ratio, is being developed for such a challenging mission. In this publication, we show that barely taking a long-exposure image does not provide much gain for coronagraphic imaging with adaptive optics. We furthermore » discuss a speckle subtraction and suppression technique that fully takes advantage of the high contrast provided by the coronagraph, as well as the wave front corrected by the adaptive optics. This technique works well for coronagraphic imaging with conventional adaptive optics with a moderate Strehl ratio, as well as for extreme adaptive optics with a high Strehl ratio. We show how to substrate and suppress speckle noise efficiently up to the third order, which is critical for future ground-based high-contrast imaging. Numerical simulations are conducted to fully demonstrate this technique.« less

Experimental performance evaluation of software defined networking (SDN) based data communication networks for large scale flexi-grid optical networks.

PubMed

Zhao, Yongli; He, Ruiying; Chen, Haoran; Zhang, Jie; Ji, Yuefeng; Zheng, Haomian; Lin, Yi; Wang, Xinbo

2014-04-21

Software defined networking (SDN) has become the focus in the current information and communication technology area because of its flexibility and programmability. It has been introduced into various network scenarios, such as datacenter networks, carrier networks, and wireless networks. Optical transport network is also regarded as an important application scenario for SDN, which is adopted as the enabling technology of data communication networks (DCN) instead of general multi-protocol label switching (GMPLS). However, the practical performance of SDN based DCN for large scale optical networks, which is very important for the technology selection in the future optical network deployment, has not been evaluated up to now. In this paper we have built a large scale flexi-grid optical network testbed with 1000 virtual optical transport nodes to evaluate the performance of SDN based DCN, including network scalability, DCN bandwidth limitation, and restoration time. A series of network performance parameters including blocking probability, bandwidth utilization, average lightpath provisioning time, and failure restoration time have been demonstrated under various network environments, such as with different traffic loads and different DCN bandwidths. The demonstration in this work can be taken as a proof for the future network deployment.

Opto-mechanical design of ShaneAO: the adaptive optics system for the 3-meter Shane Telescope

NASA Astrophysics Data System (ADS)

Ratliff, C.; Cabak, J.; Gavel, D.; Kupke, R.; Dillon, D.; Gates, E.; Deich, W.; Ward, J.; Cowley, D.; Pfister, T.; Saylor, M.

2014-07-01

A Cassegrain mounted adaptive optics instrument presents unique challenges for opto-mechanical design. The flexure and temperature tolerances for stability are tighter than those of seeing limited instruments. This criteria requires particular attention to material properties and mounting techniques. This paper addresses the mechanical designs developed to meet the optical functional requirements. One of the key considerations was to have gravitational deformations, which vary with telescope orientation, stay within the optical error budget, or ensure that we can compensate with a steering mirror by maintaining predictable elastic behavior. Here we look at several cases where deformation is predicted with finite element analysis and Hertzian deformation analysis and also tested. Techniques used to address thermal deformation compensation without the use of low CTE materials will also be discussed.

Correlation of Predicted and Observed Optical Properties of Multilayer Thermal Control Coatings

NASA Technical Reports Server (NTRS)

Jaworske, Donald A.

1998-01-01

Thermal control coatings on spacecraft will be increasingly important, as spacecraft grow smaller and more compact. New thermal control coatings will be needed to meet the demanding requirements of next generation spacecraft. Computer programs are now available to design optical coatings and one such program was used to design several thermal control coatings consisting of alternating layers of WO3 and SiO2. The coatings were subsequently manufactured with electron beam evaporation and characterized with both optical and thermal techniques. Optical data were collected in both the visible region of the spectrum and the infrared. Predictions of solar absorptance and infrared emittance were successfully correlated to the observed thermal control properties. Functional performance of the coatings was verified in a bench top thermal vacuum chamber.

Space Optics for the 21st Century

NASA Technical Reports Server (NTRS)

Bilbro, James W.

2006-01-01

Technological advances over the last decade in metrology, fabrication techniques and materials have made a significant impact on spacebased astronomy and together with advances in adaptive optics offer the opportunity for even more radical changes in the future. The Hubble Space Telescope primary mirror is 2.4 meters in diameter and weighs on the order of 150 kilograms per square meter. The technology demonstration mirrors developed for the James Webb Telescope had an order of magnitude less in area density and developments in membrane optics offer the opportunity to achieve another order of magnitude decrease. Similar advances in mirrors for x-ray astronomy means that across the spectrum future space based telescopes will have greater and greater collecting areas with ever increasing resolution.

Analysis of intrinsic optical bistability in Tm-doped laser-related crystals

NASA Astrophysics Data System (ADS)

Noginov, M. A.; Vondrova, M.; Casimir, D.

2003-11-01

We predict and theoretically study intrinsic optical bistability (IOB) mediated by nonlinear energy transfer processes in rare-earth-doped laser-related crystals. In particular, we investigate Tm-Ho and Tm-Yb systems, in which avalanche pumping is overimposed by energy transfer up-conversion. We predict that IOB can be experimentally observed in (Tm,Yb):BaY2F8 crystals in a wide range of experimentally achievable parameters.

First principles calculation of material properties of group IV elements and III-V compounds

NASA Astrophysics Data System (ADS)

Malone, Brad Dean

This thesis presents first principles calculations on the properties of group IV elements and group III-V compounds. It includes investigations into what structure a material is likely to form in, and given that structure, what are its electronic, optical, and lattice dynamical properties as well as what are the properties of defects that might be introduced into the sample. The thesis is divided as follows: • Chapter 1 contains some of the conceptual foundations used in the present work. These involve the major approximations which allow us to approach the problem of systems with huge numbers of interacting electrons and atomic cores. • Then, in Chapter 2, we discuss one of the major limitations to the DFT formalism introduced in Chapter 1, namely its inability to predict the quasiparticle spectra of materials and in particular the band gap of a semiconductor. We introduce a Green's function approach to the electron self-energy Sigma known as the GW approximation and use it to compute the quasiparticle band structures of a number of group IV and III-V semiconductors. • In Chapter 3 we present a first-principles study of a number of high-pressure metastable phases of Si with tetrahedral bonding. The phases studied include all experimentally determined phases that result from decompression from the metallic beta-Sn phase, specifically the BC8 (Si-III), hexagonal diamond (Si-IV), and R8 (Si-XII). In addition to these, we also study the hypothetical ST12 structure found upon decompression from beta-Sn in germanium. • Our attention is then turned to the first principles calculations of optical properties in Chapter 4. The Bethe-Salpeter equation is then solved to obtain the optical spectrum of this material including electron-hole interactions. The calculated optical spectrum is compared with experimental data for other forms of silicon commonly used in photovoltaic devices, namely the cubic, polycrystalline, and amorphous forms. • In Chapter 5 we present first principles calculations of the quasiparticle and optical excitation spectra of recently predicted silicon and germanium polytypes in the body-centered-tetragonal (bct) structure. The quasiparticle spectra calculated within the GW approximation predict that both silicon and germanium in the bct structure are small band gap materials. The optical spectra are then evaluated by solving the Bethe-Salpeter equation taking into account. • We examine the low-pressure phases of Ge in Chapter 6 by performing first principles calculations of the electronic structure and lattice dynamics of the R8, BC8, ST12, and hexagonal diamond structures of Ge. To aid future experimental investigation, we include predictions of the Raman-active frequencies of these phases as well as present the full phonon dispersion throughout the zone. • In Chapter 7 we demonstrate how first principles calculations can be used to predict new structures. In a study aimed at finding new useful forms of silicon, we use an ab initio random structure searching (AIRSS) method to identify a new phase of silicon in the Ibamstructure. The Ibam phase is found to be semimetallic within density functional theory with a small band overlap, and it is expected that quasiparticle corrections using the GW approximation would yield a semiconducting state with a small band gap. • We present a first-principles study of boron and phosphorus substitutional defects in Si-XII in Chapter 8. Recent result from nanoindentation experiments reveal that the Si-XII phase is semiconducting and has the interesting property that it can be doped n- and p-type at room temperature without an annealing step. Using the hybrid functional of Heyd, Scuseria, and Ernzerhof (HSE), we examine the formation energies of the B and P defects at the two distinct atomic sites in Si-XII to find on which site the substitutional defects are more easily accommodated. We also estimate the thermodynamic transition levels of each defect in its relevant charge states. (Abstract shortened by UMI.).

Prediction and Prescription in Systems Modeling

DTIC Science & Technology

1988-06-30

are so fascinated by prediction of the future -- whether achieved through horoscopes or otherwise. The future is our future, or at least the future...entirely true , has enormous import for public policy, and could have been inferred from textbook treatments of linear dynamic systems without any

Gambling and the Reasoned Action Model: Predicting Past Behavior, Intentions, and Future Behavior.

PubMed

Dahl, Ethan; Tagler, Michael J; Hohman, Zachary P

2018-03-01

Gambling is a serious concern for society because it is highly addictive and is associated with a myriad of negative outcomes. The current study applied the Reasoned Action Model (RAM) to understand and predict gambling intentions and behavior. Although prior studies have taken a reasoned action approach to understand gambling, no prior study has fully applied the RAM or used the RAM to predict future gambling. Across two studies the RAM was used to predict intentions to gamble, past gambling behavior, and future gambling behavior. In study 1 the model significantly predicted intentions and past behavior in both a college student and Amazon Mechanical Turk sample. In study 2 the model predicted future gambling behavior, measured 2 weeks after initial measurement of the RAM constructs. This study stands as the first to show the utility of the RAM in predicting future gambling behavior. Across both studies, attitudes and perceived normative pressure were the strongest predictors of intentions to gamble. These findings provide increased understanding of gambling and inform the development of gambling interventions based on the RAM.

Temporal effects in trend prediction: identifying the most popular nodes in the future.

PubMed

Zhou, Yanbo; Zeng, An; Wang, Wei-Hong

2015-01-01

Prediction is an important problem in different science domains. In this paper, we focus on trend prediction in complex networks, i.e. to identify the most popular nodes in the future. Due to the preferential attachment mechanism in real systems, nodes' recent degree and cumulative degree have been successfully applied to design trend prediction methods. Here we took into account more detailed information about the network evolution and proposed a temporal-based predictor (TBP). The TBP predicts the future trend by the node strength in the weighted network with the link weight equal to its exponential aging. Three data sets with time information are used to test the performance of the new method. We find that TBP have high general accuracy in predicting the future most popular nodes. More importantly, it can identify many potential objects with low popularity in the past but high popularity in the future. The effect of the decay speed in the exponential aging on the results is discussed in detail.

Temporal Effects in Trend Prediction: Identifying the Most Popular Nodes in the Future

PubMed Central

Zhou, Yanbo; Zeng, An; Wang, Wei-Hong

2015-01-01

Prediction is an important problem in different science domains. In this paper, we focus on trend prediction in complex networks, i.e. to identify the most popular nodes in the future. Due to the preferential attachment mechanism in real systems, nodes’ recent degree and cumulative degree have been successfully applied to design trend prediction methods. Here we took into account more detailed information about the network evolution and proposed a temporal-based predictor (TBP). The TBP predicts the future trend by the node strength in the weighted network with the link weight equal to its exponential aging. Three data sets with time information are used to test the performance of the new method. We find that TBP have high general accuracy in predicting the future most popular nodes. More importantly, it can identify many potential objects with low popularity in the past but high popularity in the future. The effect of the decay speed in the exponential aging on the results is discussed in detail. PMID:25806810

Perceived Surface Slant Is Systematically Biased in the Actively-Generated Optic Flow

PubMed Central

Fantoni, Carlo; Caudek, Corrado; Domini, Fulvio

2012-01-01

Humans make systematic errors in the 3D interpretation of the optic flow in both passive and active vision. These systematic distortions can be predicted by a biologically-inspired model which disregards self-motion information resulting from head movements (Caudek, Fantoni, & Domini 2011). Here, we tested two predictions of this model: (1) A plane that is stationary in an earth-fixed reference frame will be perceived as changing its slant if the movement of the observer's head causes a variation of the optic flow; (2) a surface that rotates in an earth-fixed reference frame will be perceived to be stationary, if the surface rotation is appropriately yoked to the head movement so as to generate a variation of the surface slant but not of the optic flow. Both predictions were corroborated by two experiments in which observers judged the perceived slant of a random-dot planar surface during egomotion. We found qualitatively similar biases for monocular and binocular viewing of the simulated surfaces, although, in principle, the simultaneous presence of disparity and motion cues allows for a veridical recovery of surface slant. PMID:22479473

Thermal Testing of a Stacked Core Mirror for UV Applications

NASA Technical Reports Server (NTRS)

Matthews, Gary; Kirk, Charles S.; Maffett, Steven; Hanson, Craig; Eng, Ron; Stahl, H. Philip

2013-01-01

The ASTRO2010 Decadal Survey stated that an advanced large-aperture ultraviolet, optical, near-infrared (UVOIR) telescope is required to enable the next generation of compelling astrophysics and exoplanet science; and, that present technology is not mature enough to affordably build and launch any potential UVOIR mission concept. Under Science and Technology funding, NASA's Marshall Space Flight Center and ITT Exelis have developed a more cost effective process to make 4m monolithic spaceflight UV quality, low areal density, thermally and dynamically stable primary mirrors. A proof of concept mirror was built and tested down to 250K which would allow imaging out to 2.5 microns. This mirror was thermally tested at the Marshall Spaceflight Center to understand the thermal changes between the processing temperature of 293K and the potential low end of the operational temperature of 250K. Isothermal testing results and front plate gradient results have been evaluated and compared to analysis predictions. Measurement of gravity effects on surface figure will be compared to analytical predictions. Future testing of a larger Pathfinder mirror will also be discussed.

Uncertainty characterization of particle location from refocused plenoptic images.

PubMed

Hall, Elise M; Guildenbecher, Daniel R; Thurow, Brian S

2017-09-04

Plenoptic imaging is a 3D imaging technique that has been applied for quantification of 3D particle locations and sizes. This work experimentally evaluates the accuracy and precision of such measurements by investigating a static particle field translated to known displacements. Measured 3D displacement values are determined from sharpness metrics applied to volumetric representations of the particle field created using refocused plenoptic images, corrected using a recently developed calibration technique. Comparison of measured and known displacements for many thousands of particles allows for evaluation of measurement uncertainty. Mean displacement error, as a measure of accuracy, is shown to agree with predicted spatial resolution over the entire measurement domain, indicating robustness of the calibration methods. On the other hand, variation in the error, as a measure of precision, fluctuates as a function of particle depth in the optical direction. Error shows the smallest variation within the predicted depth of field of the plenoptic camera, with a gradual increase outside this range. The quantitative uncertainty values provided here can guide future measurement optimization and will serve as useful metrics for design of improved processing algorithms.

Status of Technology Development to enable Large Stable UVOIR Space Telescopes

NASA Astrophysics Data System (ADS)

Stahl, H. Philip; MSFC AMTD Team

2017-01-01

NASA MSFC has two funded Strategic Astrophysics Technology projects to develop technology for potential future large missions: AMTD and PTC. The Advanced Mirror Technology Development (AMTD) project is developing technology to make mechanically stable mirrors for a 4-meter or larger UVOIR space telescope. AMTD is demonstrating this technology by making a 1.5 meter diameter x 200 mm thick ULE(C) mirror that is 1/3rd scale of a full size 4-m mirror. AMTD is characterizing the mechanical and thermal performance of this mirror and of a 1.2-meter Zerodur(R) mirror to validate integrate modeling tools. Additionally, AMTD has developed integrated modeling tools which are being used to evaluate primary mirror systems for a potential Habitable Exoplanet Mission and analyzed the interaction between optical telescope wavefront stability and coronagraph contrast leakage. Predictive Thermal Control (PTC) project is developing technology to enable high stability thermal wavefront performance by using integrated modeling tools to predict and actively control the thermal environment of a 4-m or larger UVOIR space telescope.

Algorithms and the Future of Music Education: A Response to Shuler

ERIC Educational Resources Information Center

Thibeault, Matthew D.

2014-01-01

This article is a response to Shuler's 2001 article predicting the future of music education. The respondent assesses Shuler's predictions, finding that many have come true but critiquing Shuler's overall positive assessment. The respondent then goes on to make one prediction about the future of music education: that algorithms will…

Optical fiber sensors and signal processing for intelligent structure monitoring

NASA Technical Reports Server (NTRS)

Thomas, Daniel; Cox, Dave; Lindner, D. K.; Claus, R. O.

1989-01-01

Few mode optical fibers have been shown to produce predictable interference patterns when placed under strain. The use is described of a modal domain sensor in a vibration control experiment. An optical fiber is bonded along the length of a flexible beam. Output from the modal domain sensor is used to suppress vibrations induced in the beam. A distributed effect model for the modal domain sensor is developed. This model is combined with the beam and actuator dynamics to produce a system suitable for control design. Computer simulations predict open and closed loop dynamic responses. An experimental apparatus is described and experimental results are presented.

Experimental demonstration of free-space optical vortex transmutation with polygonal lenses.

PubMed

Gao, Nan; Xie, Changqing

2012-08-01

Vortex transmutation was predicted to take place when vortices interact with systems possessing discrete rotational symmetries of finite order [Phys. Rev. Lett.95, 123901 (2005)]. Here we report what is believed to be the first experimental demonstration of vortex transmutation. We show that in free space, by simply inserting polygonal lenses into the optical path, the central vorticity of a coaxially incident optical vortex can be changed following the modular transmutation rule. We generate the wavefront at the exit face of the lenses with computer generated holograms and measure the output vorticity using the interference patterns at the focal plane. The results agree well with theoretical predictions.

Networking in 2005: Its only Limitations May Be the Boundaries of Imagination.

ERIC Educational Resources Information Center

Butters, Gerry

1998-01-01

Presents insights into the state of networking of the near future. Discusses the promotion of virtual reality in every-day society; the unlimited bandwidth of optical networking; and terrestrial wireless links tethered to optical tools. (AEF)

Optics Developments for X-Ray Astronomy

NASA Technical Reports Server (NTRS)

Ramsey, Brian

2014-01-01

X-ray optics has revolutionized x-ray astronomy. The degree of background suppression that these afford, have led to a tremendous increase in sensitivity. The current Chandra observatory has the same collecting area (approx. 10(exp 3)sq cm) as the non-imaging UHURU observatory, the first x-ray observatory which launched in 1970, but has 5 orders of magnitude more sensitivity due to its focusing optics. In addition, its 0.5 arcsec angular resolution has revealed a wealth of structure in many cosmic x-ray sources. The Chandra observatory achieved its resolution by using relatively thick pieces of Zerodur glass, which were meticulously figured and polished to form the four-shell nested array. The resulting optical assembly weighed around 1600 kg, and cost approximately $0.5B. The challenge for future x-ray astronomy missions is to greatly increase the collecting area (by one or more orders of magnitude) while maintaining high angular resolution, and all within realistic mass and budget constraints. A review of the current status of US optics for x-ray astronomy will be provided along with the challenges for future developments.

Recent Developments Of Optical Fiber Sensors For Automotive Use

NASA Astrophysics Data System (ADS)

Sasayama, Takao; Oho, Shigeru; Kuroiwa, Hiroshi; Suzuki, Seikoo

1987-12-01

Optical fiber sensing technologies are expected to apply for many future electronic control systems in automobiles, because of their original outstanding features, such as high noise immunity, high heat resistance, and flexible light propagation paths which can be applicable to measure the movements and directions of the mobiles. In this paper, two typical applications of fiber sensing technologies in automobiles have been described in detail. The combustion flame detector is one of the typical applications of a fiber spectroscopic technology which utilizes the feature of high noise and heat resistibility and remote sensibility. Measurements of engine combustion conditions, such as the detonation, the combustion initiation, and the air-fuel ratio, have been demonstrated in an experimental fiber sensing method. Fiber interferometers, such as a fiber gyroscope, have a lot of possibilities in future mobile applications because they are expandable to many kinds of measurements for movements and physical variables. An optical fiber gyroscope utilizing the single polarized optical fiber and optical devices has been developed. Quite an accurate measurement of vehicle position was displayed on a prototype navigation system which installed the fiber gyroscope as a rotational speed sensor.

Helicopter Rotor Noise Prediction: Background, Current Status, and Future Direction

NASA Technical Reports Server (NTRS)

Brentner, Kenneth S.

1997-01-01

Helicopter noise prediction is increasingly important. The purpose of this viewgraph presentation is to: 1) Put into perspective the recent progress; 2) Outline current prediction capabilities; 3) Forecast direction of future prediction research; 4) Identify rotorcraft noise prediction needs. The presentation includes an historical perspective, a description of governing equations, and the current status of source noise prediction.

Numerical simulations of the hard X-ray pulse intensity distribution at the Linac Coherent Light Source

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

Pardini, Tom; Aquila, Andrew; Boutet, Sebastien

Numerical simulations of the current and future pulse intensity distributions at selected locations along the Far Experimental Hall, the hard X-ray section of the Linac Coherent Light Source (LCLS), are provided. Estimates are given for the pulse fluence, energy and size in and out of focus, taking into account effects due to the experimentally measured divergence of the X-ray beam, and measured figure errors of all X-ray optics in the beam path. Out-of-focus results are validated by comparison with experimental data. Previous work is expanded on, providing quantitatively correct predictions of the pulse intensity distribution. Numerical estimates in focus aremore » particularly important given that the latter cannot be measured with direct imaging techniques due to detector damage. Finally, novel numerical estimates of improvements to the pulse intensity distribution expected as part of the on-going upgrade of the LCLS X-ray transport system are provided. As a result, we suggest how the new generation of X-ray optics to be installed would outperform the old one, satisfying the tight requirements imposed by X-ray free-electron laser facilities.« less

Numerical simulations of the hard X-ray pulse intensity distribution at the Linac Coherent Light Source

DOE PAGES

Pardini, Tom; Aquila, Andrew; Boutet, Sebastien; ...

2017-06-15

Numerical simulations of the current and future pulse intensity distributions at selected locations along the Far Experimental Hall, the hard X-ray section of the Linac Coherent Light Source (LCLS), are provided. Estimates are given for the pulse fluence, energy and size in and out of focus, taking into account effects due to the experimentally measured divergence of the X-ray beam, and measured figure errors of all X-ray optics in the beam path. Out-of-focus results are validated by comparison with experimental data. Previous work is expanded on, providing quantitatively correct predictions of the pulse intensity distribution. Numerical estimates in focus aremore » particularly important given that the latter cannot be measured with direct imaging techniques due to detector damage. Finally, novel numerical estimates of improvements to the pulse intensity distribution expected as part of the on-going upgrade of the LCLS X-ray transport system are provided. As a result, we suggest how the new generation of X-ray optics to be installed would outperform the old one, satisfying the tight requirements imposed by X-ray free-electron laser facilities.« less

Optical coherence tomography spectral analysis for detecting apoptosis in vitro and in vivo

NASA Astrophysics Data System (ADS)

Farhat, Golnaz; Giles, Anoja; Kolios, Michael C.; Czarnota, Gregory J.

2015-12-01

Apoptosis is a form of programmed cell death characterized by a series of predictable morphological changes at the subcellular level, which modify the light-scattering properties of cells. We present a spectroscopic optical coherence tomography (OCT) technique to detect changes in subcellular morphology related to apoptosis in vitro and in vivo. OCT data were acquired from acute myeloid leukemia (AML) cells treated with cisplatin over a 48-h period. The backscatter spectrum of the OCT signal acquired from the cell samples was characterized by calculating its in vitro integrated backscatter (IB) and spectral slope (SS). The IB increased with treatment duration, while the SS decreased, with the most significant changes occurring after 24 to 48 h of treatment. These changes coincided with striking morphological transformations in the cells and their nuclei. Similar trends in the spectral parameter values were observed in vivo in solid tumors grown from AML cells in mice, which were treated with chemotherapy and radiation. Our results provide a strong foundation from which future experiments may be designed to further understand the effect of cellular morphology and kinetics of apoptosis on the OCT signal and demonstrate the feasibility of using this technique in vivo.

Do future commercial broadband communication satellites really need laser-communication intersatellite links (ISLs)?

NASA Astrophysics Data System (ADS)

Freidell, James E.

1997-04-01

Large commercial satellite programs requiring ISLs are growing in number and maturing. An important segment of the commercial satellite market, and its ISL needs, is discussed in the paper. ISL value will increase as long-haul terrestrial backbones become increasingly congested. Providing interregional and intercontinental connectivity via ISL presents far lower cost and fewer problems than relying on terrestrial fiber-optic networks. To demonstrate this, a new metric is proposed which allows 'apples-to- apples' cost/performance comparisons between laser communications in GEO, LEO, and terrestrial fiber-optics. ISL requirements in to the next decade are predicted >= 50-100 Gb/s full duplex. Many attitudinal changes must be embraced among those who choose to focus on this new commercial business. Foremost among these is a preponderance to delivering fully acceptable hardware fast and at low cost, as opposed to merely designing such. Considerable attention must be given business considerations foreign to professionals who have spent time in the government or government contracting sectors. Successful ISL customers will come to recognize that ISLs are not commodity products. Failure to embrace these attitudes will nonetheless constitute decision to which the commercial market, and particularly the financial market, will appropriately respond.

An all-reflective wide-angle flat-field telescope for space

NASA Technical Reports Server (NTRS)

Hallam, K. L.; Howell, B. J.; Wilson, M. E.

1984-01-01

An all-reflective wide-angle flat-field telescope (WAFFT) designed and built at Goddard Space Flight Center demonstrates the markedly improved wide-angle imaging capability which can be achieved with a design based on a recently announced class of unobscured 3-mirror optical systems. Astronomy and earth observation missions in space dictate the necessity or preference for wide-angle all-reflective systems which can provide UV through IR wavelength coverage and tolerate the space environment. An initial prototype unit has been designed to meet imaging requirements suitable for monitoring the ultraviolet sky from space. The unobscured f/4, 36 mm efl system achieves a full 20 x 30 deg field of view with resolution over a flat focal surface that is well matched for use with advanced ultraviolet image array detectors. Aspects of the design and fabrication approach, which have especially important bearing on the system solution, are reviewed; and test results are compared with the analytic performance predictions. Other possible applications of the WAFFT class of imaging system are briefly discussed. The exceptional wide-angle, high quality resolution, and very wide spectral coverage of the WAFFT-type optical system could make it a very important tool for future space research.

Relating remotely sensed optical variability to marine benthic biodiversity.

PubMed

Herkül, Kristjan; Kotta, Jonne; Kutser, Tiit; Vahtmäe, Ele

2013-01-01

Biodiversity is important in maintaining ecosystem viability, and the availability of adequate biodiversity data is a prerequisite for the sustainable management of natural resources. As such, there is a clear need to map biodiversity at high spatial resolutions across large areas. Airborne and spaceborne optical remote sensing is a potential tool to provide such biodiversity data. The spectral variation hypothesis (SVH) predicts a positive correlation between spectral variability (SV) of a remotely sensed image and biodiversity. The SVH has only been tested on a few terrestrial plant communities. Our study is the first attempt to apply the SVH in the marine environment using hyperspectral imagery recorded by Compact Airborne Spectrographic Imager (CASI). All coverage-based diversity measures of benthic macrophytes and invertebrates showed low but statistically significant positive correlations with SV whereas the relationship between biomass-based diversity measures and SV were weak or lacking. The observed relationships did not vary with spatial scale. SV had the highest independent effect among predictor variables in the statistical models of coverage-derived total benthic species richness and Shannon index. Thus, the relevance of SVH in marine benthic habitats was proved and this forms a prerequisite for the future use of SV in benthic biodiversity assessments.

Excitonic gap formation in pumped Dirac materials

NASA Astrophysics Data System (ADS)

Triola, Christopher; Pertsova, Anna; Markiewicz, Robert S.; Balatsky, Alexander V.

2017-05-01

Recent pump-probe experiments demonstrate the possibility that Dirac materials may be driven into transient excited states describable by two chemical potentials, one for the electrons and one for the holes. Given the Dirac nature of the spectrum, such an inverted population allows the optical tunability of the density of states of the electrons and holes, effectively offering control of the strength of the Coulomb interaction. Here we discuss the feasibility of realizing transient excitonic instabilities in optically pumped Dirac materials. We demonstrate, theoretically, the reduction of the critical coupling leading to the formation of a transient condensate of electron-hole pairs and identify signatures of this state. Furthermore, we provide guidelines for experiments by both identifying the regimes in which such exotic many-body states are more likely to be observed and estimating the magnitude of the excitonic gap for a few important examples of existing Dirac materials. We find a set of material parameters for which our theory predicts large gaps and high critical temperatures and which could be realized in future Dirac materials. We also comment on transient excitonic instabilities in three-dimensional Dirac and Weyl semimetals. This study provides an example of a transient collective instability in driven Dirac materials.

Growth of single crystals of organic salts with large second-order optical nonlinearities by solution processes for devices

NASA Technical Reports Server (NTRS)

Leslie, Thomas M.

1995-01-01

Data obtained from the electric field induced second harmonic generation (EFISH) and Kurtz Powder Methods will be provided to MSFC for further refinement of their method. A theoretical model for predicting the second-order nonlinearities of organic salts is being worked on. Another task is the synthesis of a number of salts with various counterions. Several salts with promising SHG activities and new salts will be tested for the presence of two crystalline forms. The materials will be recrystallized from dry and wet solvents and compared for SHG efficiency. Salts that have a high SHG efficiency and no tendency to form hydrates will be documented. The synthesis of these materials are included in this report. A third task involves method to aid in the growth of large, high quality single crystals by solution processes. These crystals will be characterized for their applicability in the fabrication of devices that will be incorporated into optical computers in future programs. Single crystals of optimum quality may be obtained by crystal growth in low-gravity. The final task is the design of a temperature lowering single crystal growth apparatus for ground based work. At least one prototype will be built.

Magneto-optical Kerr effect of a Ni2.00Mn1.16Ga0.84 single crystal across austenite and intermartensite transitions

NASA Astrophysics Data System (ADS)

Fikáček, Jan; Heczko, Oleg; Kopecký, Vít; Kaštil, Jiří; Honolka, Jan

2018-04-01

We carried out magneto-optical Kerr effect (MOKE) and magnetization measurements on a single crystal of Ni2.00Mn1.16Ga0.84, which is a magnetic shape memory material with application potential for actuator devices or for energy recuperation. Up to the time of our study, there had been reports of MOKE measurements in polar geometry. Against earlier predictions, we show that surface magnetic states of the martensite and the austenite can be also probed efficiently via longitudinal MOKE. A single-variant magnetic state prepared at room temperature is characterized by square-shaped ferromagnetic hysteresis loops yielding coercive fields, which are key material properties for future applications. Temperature dependencies of Kerr rotation were found to be linearly proportional to magnetization for martensitic phases. After passing through an inter-martensitic structural transition below room temperature in zero magnetic field, the coercive fields are more than doubled in comparison with the room temperature values. Above room temperature where an austenite structure is formed, MOKE signals are dominated by quadratic contributions and the magnitude of Kerr rotation drops due to changes in the electronic and magnetic domains structure.

Review of optical freeform surface representation technique and its application

NASA Astrophysics Data System (ADS)

Ye, Jingfei; Chen, Lu; Li, Xinhua; Yuan, Qun; Gao, Zhishan

2017-11-01

Modern advanced manufacturing and testing technologies allow the application of freeform optical elements. Compared with traditional spherical surfaces, an optical freeform surface has more degrees of freedom in optical design and provides substantially improved imaging performance. In freeform optics, the representation technique of a freeform surface has been a fundamental and key research topic in recent years. Moreover, it has a close relationship with other aspects of the design, manufacturing, testing, and application of optical freeform surfaces. Improvements in freeform surface representation techniques will make a significant contribution to the further development of freeform optics. We present a detailed review of the different types of optical freeform surface representation techniques and their applications and discuss their properties and differences. Additionally, we analyze the future trends of optical freeform surface representation techniques.

Optical atomic clocks

NASA Astrophysics Data System (ADS)

Poli, N.; Oates, C. W.; Gill, P.; Tino, G. M.

2013-12-01

In the last ten years extraordinary results in time and frequency metrology have been demonstrated. Frequency-stabilization techniques for continuous-wave lasers and femtosecond optical frequency combs have enabled a rapid development of frequency standards based on optical transitions in ultra-cold neutral atoms and trapped ions. As a result, today's best performing atomic clocks tick at an optical rate and allow scientists to perform high-resolution measurements with a precision approaching a few parts in 1018. This paper reviews the history and the state of the art in optical-clock research and addresses the implementation of optical clocks in a possible future redefinition of the SI second as well as in tests of fundamental physics.

Universal Behavior of Quantum Spin Liquid and Optical Conductivity in the Insulator Herbertsmithite

NASA Astrophysics Data System (ADS)

Shaginyan, V. R.; Msezane, A. Z.; Stephanovich, V. A.; Popov, K. G.; Japaridze, G. S.

2018-04-01

We analyze optical conductivity with the goal to demonstrate experimental manifestation of a new state of matter, the so-called fermion condensate. Fermion condensates are realized in quantum spin liquids, exhibiting typical behavior of heavy-fermion metals. Measurements of the low-frequency optical conductivity collected on the geometrically frustrated insulator herbertsmithite provide important experimental evidence of the nature of its quantum spin liquid composed of spinons. To analyze recent measurements of the herbertsmithite optical conductivity at different temperatures, we employ a model of strongly correlated quantum spin liquid located near the fermion condensation phase transition. Our theoretical analysis of the optical conductivity allows us to expose the physical mechanism of its temperature dependence. We also predict a dependence of the optical conductivity on a magnetic field. We consider an experimental manifestation (optical conductivity) of a new state of matter (so-called fermion condensate) realized in quantum spin liquids, for, in many ways, they exhibit typical behavior of heavy-fermion metals. Measurements of the low-frequency optical conductivity collected on the geometrically frustrated insulator herbertsmithite produce important experimental evidence of the nature of its quantum spin liquid composed of spinons. To analyze recent measurements of the herbertsmithite optical conductivity at different temperatures, we employ a model of a strongly correlated quantum spin liquid located near the fermion condensation phase transition. Our theoretical analysis of the optical conductivity allows us to reveal the physical mechanism of its temperature dependence. We also predict a dependence of the optical conductivity on a magnetic field.

System concepts and design examples for optical communication with planetary spacecraft

NASA Astrophysics Data System (ADS)

Lesh, James R.

Systems concepts for optical communication with future deep-space (planetary) spacecraft are described. These include not only the optical transceiver package aboard the distant spacecraft, but the earth-vicinity optical-communications receiving station as well. Both ground-based, and earth-orbiting receivers are considered. Design examples for a number of proposed or potential deep-space missions are then presented. These include an orbital mission to Saturn, a Lander and Rover mission to Mars, and an astronomical mission to a distance of 1000 astronomical units.

Optical PAyload for Lasercomm Science (OPALS) link validation

NASA Technical Reports Server (NTRS)

Biswas, Abhijit; Oaida, Bogdan V.; Andrews, Kenneth S.; Kovalik, Joseph M.; Abrahamson, Matthew J.; Wright, Malcolm W.

2015-01-01

Recently several day and nighttime links under diverse atmospheric conditions were completed using the Optical Payload for Lasercomm Science (OPALS) flight system on-board the International Space Station (ISS). In this paper we compare measured optical power and its variance at either end of the link with predictions that include atmospheric propagation models. For the 976 nm laser beacon mean power transmitted from the ground to the ISS the predicted mean irradiance of 10's of microwatts per square meter close to zenith and its decrease with range and increased air mass shows good agreement with predictions. The irradiance fluctuations sampled at 100 Hz also follow the expected increase in scintillation with air mass representative of atmospheric coherence lengths at zenith at 500 nm in the 3-8 cm range. The downlink predicted power of 100's of nanowatts was also reconciled within the uncertainty of the atmospheric losses. Expected link performance with uncoded bit-error rates less than 1E-4 required for the Reed-Solomon code to correct errors for video, text and file transmission was verified. The results of predicted and measured powers and fluctuations suggest the need for further study and refinement.

IOL calculation using paraxial matrix optics.

PubMed

Haigis, Wolfgang

2009-07-01

Matrix methods have a long tradition in paraxial physiological optics. They are especially suited to describe and handle optical systems in a simple and intuitive manner. While these methods are more and more applied to calculate the refractive power(s) of toric intraocular lenses (IOL), they are hardly used in routine IOL power calculations for cataract and refractive surgery, where analytical formulae are commonly utilized. Since these algorithms are also based on paraxial optics, matrix optics can offer rewarding approaches to standard IOL calculation tasks, as will be shown here. Some basic concepts of matrix optics are introduced and the system matrix for the eye is defined, and its application in typical IOL calculation problems is illustrated. Explicit expressions are derived to determine: predicted refraction for a given IOL power; necessary IOL power for a given target refraction; refractive power for a phakic IOL (PIOL); predicted refraction for a thick lens system. Numerical examples with typical clinical values are given for each of these expressions. It is shown that matrix optics can be applied in a straightforward and intuitive way to most problems of modern routine IOL calculation, in thick or thin lens approximation, for aphakic or phakic eyes.

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.

Impact of future climate policy scenarios on air quality and aerosol-cloud interactions using an advanced version of CESM/CAM5: Part II. Future trend analysis and impacts of projected anthropogenic emissions

NASA Astrophysics Data System (ADS)

Glotfelty, Timothy; Zhang, Yang

2017-03-01

Following a comprehensive evaluation of the Community Earth System Model modified at the North Carolina State University (CESM-NCSU), Part II describes the projected changes in the future state of the atmosphere under the representative concentration partway scenarios (RCP4.5 and 8.5) by 2100 for the 2050 time frame and examine the impact of climate change on future air quality under both scenarios, and the impact of projected emission changes under the RCP4.5 scenario on future climate through aerosol direct and indirect effects. Both the RCP4.5 and RCP8.5 simulations predict similar changes in air quality by the 2050 period due to declining emissions under both scenarios. The largest differences occur in O3, which decreases by global mean of 1.4 ppb under RCP4.5 but increases by global mean of 2.3 ppb under RCP8.5 due to differences in methane levels, and PM10, which decreases by global mean of 1.2 μg m-3 under RCP4.5 and increases by global mean of 0.2 μg m-3 under RCP8.5 due to differences in dust and sea-salt emissions under both scenarios. Enhancements in cloud formation in the Arctic and Southern Ocean and increases of aerosol optical depth (AOD) in central Africa and South Asia dominate the change in surface radiation in both scenarios, leading to global average dimming of 1.1 W m-2 and 2.0 W m-2 in the RCP4.5 and RCP8.5 scenarios, respectively. Declines in AOD, cloud formation, and cloud optical thickness from reductions of emissions of primary aerosols and aerosol precursors under RCP4.5 result in near surface warming of 0.2 °C from a global average increase of 0.7 W m-2 in surface downwelling solar radiation. This warming leads to a weakening of the Walker Circulation in the tropics, leading to significant changes in cloud and precipitation that mirror a shift in climate towards the negative phase of the El Nino Southern Oscillation.

A new European small platform: Proteus and prospected optical application missions

NASA Astrophysics Data System (ADS)

Dubois, J.-B.; Paoli, F.

2018-04-01

Progress in technology in recent years and new industrial approaches now make it possible to design valuable optical missions using a small-class satellite, like the PROTEUS multi mission platform. Some future space optical missions using existing or planned instruments, combined with the PROTEUS platform, have been assessed by AEROSPATIALE / SPACE and DEFENSE and/or the CNES (French National Space Agency).

Laser diode technology for coherent communications

NASA Technical Reports Server (NTRS)

Channin, D. J.; Palfrey, S. L.; Toda, M.

1989-01-01

The effect of diode laser characteristics on the overall performance capabilities of coherent communication systems is discussed. In particular, attention is given to optical performance issues for diode lasers in coherent systems, measurements of key performance parameters, and optical requirements for coherent single-channel and multichannel communication systems. The discussion also covers limitations imposed by diode laser optical performance on multichannel system capabilities and implications for future developments.

Wide field/planetary camera optics study. [for the large space telescope

NASA Technical Reports Server (NTRS)

1979-01-01

Design feasibility of the baseline optical design concept was established for the wide field/planetary camera (WF/PC) and will be used with the space telescope (ST) to obtain high angular resolution astronomical information over a wide field. The design concept employs internal optics to relay the ST image to a CCD detector system. Optical design performance predictions, sensitivity and tolerance analyses, manufacturability of the optical components, and acceptance testing of the two mirror Cassegrain relays are discussed.

Comparative Time Series Analysis of Aerosol Optical Depth over Sites in United States and China Using ARIMA Modeling

NASA Astrophysics Data System (ADS)

Li, X.; Zhang, C.; Li, W.

2017-12-01

Long-term spatiotemporal analysis and modeling of aerosol optical depth (AOD) distribution is of paramount importance to study radiative forcing, climate change, and human health. This study is focused on the trends and variations of AOD over six stations located in United States and China during 2003 to 2015, using satellite-retrieved Moderate Resolution Imaging Spectrometer (MODIS) Collection 6 retrievals and ground measurements derived from Aerosol Robotic NETwork (AERONET). An autoregressive integrated moving average (ARIMA) model is applied to simulate and predict AOD values. The R2, adjusted R2, Root Mean Square Error (RMSE), Mean Absolute Error (MAE), Mean Absolute Percentage Error (MAPE), and Bayesian Information Criterion (BIC) are used as indices to select the best fitted model. Results show that there is a persistent decreasing trend in AOD for both MODIS data and AERONET data over three stations. Monthly and seasonal AOD variations reveal consistent aerosol patterns over stations along mid-latitudes. Regional differences impacted by climatology and land cover types are observed for the selected stations. Statistical validation of time series models indicates that the non-seasonal ARIMA model performs better for AERONET AOD data than for MODIS AOD data over most stations, suggesting the method works better for data with higher quality. By contrast, the seasonal ARIMA model reproduces the seasonal variations of MODIS AOD data much more precisely. Overall, the reasonably predicted results indicate the applicability and feasibility of the stochastic ARIMA modeling technique to forecast future and missing AOD values.

Fast incorporation of optical flow into active polygons.

PubMed

Unal, Gozde; Krim, Hamid; Yezzi, Anthony

2005-06-01

In this paper, we first reconsider, in a different light, the addition of a prediction step to active contour-based visual tracking using an optical flow and clarify the local computation of the latter along the boundaries of continuous active contours with appropriate regularizers. We subsequently detail our contribution of computing an optical flow-based prediction step directly from the parameters of an active polygon, and of exploiting it in object tracking. This is in contrast to an explicitly separate computation of the optical flow and its ad hoc application. It also provides an inherent regularization effect resulting from integrating measurements along polygon edges. As a result, we completely avoid the need of adding ad hoc regularizing terms to the optical flow computations, and the inevitably arbitrary associated weighting parameters. This direct integration of optical flow into the active polygon framework distinguishes this technique from most previous contour-based approaches, where regularization terms are theoretically, as well as practically, essential. The greater robustness and speed due to a reduced number of parameters of this technique are additional and appealing features.

Method and apparatus for sensor fusion

NASA Technical Reports Server (NTRS)

Krishen, Kumar (Inventor); Shaw, Scott (Inventor); Defigueiredo, Rui J. P. (Inventor)

1991-01-01

Method and apparatus for fusion of data from optical and radar sensors by error minimization procedure is presented. The method was applied to the problem of shape reconstruction of an unknown surface at a distance. The method involves deriving an incomplete surface model from an optical sensor. The unknown characteristics of the surface are represented by some parameter. The correct value of the parameter is computed by iteratively generating theoretical predictions of the radar cross sections (RCS) of the surface, comparing the predicted and the observed values for the RCS, and improving the surface model from results of the comparison. Theoretical RCS may be computed from the surface model in several ways. One RCS prediction technique is the method of moments. The method of moments can be applied to an unknown surface only if some shape information is available from an independent source. The optical image provides the independent information.

TH-A-9A-01: Active Optical Flow Model: Predicting Voxel-Level Dose Prediction in Spine SBRT

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

Liu, J; Wu, Q.J.; Yin, F

2014-06-15

Purpose: To predict voxel-level dose distribution and enable effective evaluation of cord dose sparing in spine SBRT. Methods: We present an active optical flow model (AOFM) to statistically describe cord dose variations and train a predictive model to represent correlations between AOFM and PTV contours. Thirty clinically accepted spine SBRT plans are evenly divided into training and testing datasets. The development of predictive model consists of 1) collecting a sequence of dose maps including PTV and OAR (spinal cord) as well as a set of associated PTV contours adjacent to OAR from the training dataset, 2) classifying data into fivemore » groups based on PTV's locations relative to OAR, two “Top”s, “Left”, “Right”, and “Bottom”, 3) randomly selecting a dose map as the reference in each group and applying rigid registration and optical flow deformation to match all other maps to the reference, 4) building AOFM by importing optical flow vectors and dose values into the principal component analysis (PCA), 5) applying another PCA to features of PTV and OAR contours to generate an active shape model (ASM), and 6) computing a linear regression model of correlations between AOFM and ASM.When predicting dose distribution of a new case in the testing dataset, the PTV is first assigned to a group based on its contour characteristics. Contour features are then transformed into ASM's principal coordinates of the selected group. Finally, voxel-level dose distribution is determined by mapping from the ASM space to the AOFM space using the predictive model. Results: The DVHs predicted by the AOFM-based model and those in clinical plans are comparable in training and testing datasets. At 2% volume the dose difference between predicted and clinical plans is 4.2±4.4% and 3.3±3.5% in the training and testing datasets, respectively. Conclusion: The AOFM is effective in predicting voxel-level dose distribution for spine SBRT. Partially supported by NIH/NCI under grant #R21CA161389 and a master research grant by Varian Medical System.« less

Predictive analysis of optical ablation in several dermatological tumoral tissues

NASA Astrophysics Data System (ADS)

Fanjul-Vélez, F.; Blanco-Gutiérrez, A.; Salas-García, I.; Ortega-Quijano, N.; Arce-Diego, J. L.

2013-06-01

Optical techniques for treatment and characterization of biological tissues are revolutionizing several branches of medical praxis, for example in ophthalmology or dermatology. The non-invasive, non-contact and non-ionizing character of optical radiation makes it specially suitable for these applications. Optical radiation can be employed in medical ablation applications, either for tissue resection or surgery. Optical ablation may provide a controlled and clean cut on a biological tissue. This is particularly relevant in tumoral tissue resection, where a small amount of cancerous cells could make the tumor appear again. A very important aspect of tissue optical ablation is then the estimation of the affected volume. In this work we propose a complete predictive model of tissue ablation that provides an estimation of the resected volume. The model is based on a Monte Carlo approach for the optical propagation of radiation inside the tissue, and a blow-off model for tissue ablation. This model is applied to several types of dermatological tumoral tissues, specifically squamous cells, basocellular and infiltrative carcinomas. The parameters of the optical source are varied and the estimated resected volume is calculated. The results for the different tumor types are presented and compared. This model can be used for surgical planning, in order to assure the complete resection of the tumoral tissue.

Advanced technologies for future ground-based, laser-interferometric gravitational wave detectors

PubMed Central

Hammond, Giles; Hild, Stefan; Pitkin, Matthew

2014-01-01

We present a review of modern optical techniques being used and developed for the field of gravitational wave detection. We describe the current state-of-the-art of gravitational waves detector technologies with regard to optical layouts, suspensions and test masses. We discuss the dominant sources and noise in each of these subsystems and the developments that will help mitigate them for future generations of detectors. We very briefly summarise some of the novel astrophysics that will be possible with these upgraded detectors. PMID:25705087

The Need for Optical Means as an Alternative for Electronic Computing

NASA Technical Reports Server (NTRS)

Adbeldayem, Hossin; Frazier, Donald; Witherow, William; Paley, Steve; Penn, Benjamin; Bank, Curtis; Whitaker, Ann F. (Technical Monitor)

2001-01-01

An increasing demand for faster computers is rapidly growing to encounter the fast growing rate of Internet, space communication, and robotic industry. Unfortunately, the Very Large Scale Integration technology is approaching its fundamental limits beyond which the device will be unreliable. Optical interconnections and optical integrated circuits are strongly believed to provide the way out of the extreme limitations imposed on the growth of speed and complexity of nowadays computations by conventional electronics. This paper demonstrates two ultra-fast, all-optical logic gates and a high-density storage medium, which are essential components in building the future optical computer.

Precision injection molding of freeform optics

NASA Astrophysics Data System (ADS)

Fang, Fengzhou; Zhang, Nan; Zhang, Xiaodong

2016-08-01

Precision injection molding is the most efficient mass production technology for manufacturing plastic optics. Applications of plastic optics in field of imaging, illumination, and concentration demonstrate a variety of complex surface forms, developing from conventional plano and spherical surfaces to aspheric and freeform surfaces. It requires high optical quality with high form accuracy and lower residual stresses, which challenges both optical tool inserts machining and precision injection molding process. The present paper reviews recent progress in mold tool machining and precision injection molding, with more emphasis on precision injection molding. The challenges and future development trend are also discussed.

Propagating modes in gain-guided optical fibers.

PubMed

Siegman, A E

2003-08-01

Optical fibers in which gain-guiding effects are significant or even dominant compared with conventional index guiding may become of practical interest for future high-power single-mode fiber lasers. I derive the propagation characteristics of symmetrical slab waveguides and cylindrical optical fibers having arbitrary amounts of mixed gain and index guiding, assuming a single uniform transverse profile for both the gain and the refractive-index steps. Optical fibers of this type are best characterized by using a complex-valued v-squared parameter in place of the real-valued v parameter commonly used to describe conventional index-guided optical fibers.

Mariner-Venus-Mercury optical navigation demonstration - Results and implications for future missions

NASA Technical Reports Server (NTRS)

Acton, C. H., Jr.; Ohtakay, H.

1975-01-01

Optical navigation uses spacecraft television pictures of a target body against a known star background in a process which relates the spacecraft trajectory to the target body. This technology was used in the Mariner-Venus-Mercury mission, with the optical data processed in near-real-time, simulating a mission critical environment. Optical data error sources were identified, and a star location error analysis was carried out. Several methods for selecting limb crossing coordinates were used, and a limb smear compensation was introduced. Omission of planetary aberration corrections was the source of large optical residuals.

Master's level education in biomedical optics: four-year experience at the University of Latvia

NASA Astrophysics Data System (ADS)

Spigulis, Janis

2000-06-01

Pilot program for Master's studies on Biomedical Optics has been developed and launched at University of Latvia in 1995. The Curriculum contains several basic subjects like Fundamentals of Biomedical Optics, Medical Lightguides, Anatomy and Physiology, Lasers and Non-coherent Light Sources, Optical Instrumentation for Healthcare, Optical Methods for Patient Treatment, Basic Physics, etc. Special English Terminology and Laboratory-Clinical Praxis are also involved, and the Master Theses is the final step for the degree award. Following one four-year teaching experience, some observations, conclusions and eventual future activities are discussed.

Radio Frequency Magneto-Optical Trapping of CaF with High Density.

PubMed

Anderegg, Loïc; Augenbraun, Benjamin L; Chae, Eunmi; Hemmerling, Boerge; Hutzler, Nicholas R; Ravi, Aakash; Collopy, Alejandra; Ye, Jun; Ketterle, Wolfgang; Doyle, John M

2017-09-08

We demonstrate significantly improved magneto-optical trapping of molecules using a very slow cryogenic beam source and either rf modulated or dc magnetic fields. The rf magneto-optical trap (MOT) confines 1.0(3)×10^{5} CaF molecules at a density of 7(3)×10^{6}  cm^{-3}, which is an order of magnitude greater than previous molecular MOTs. Near Doppler-limited temperatures of 340(20)  μK are attained. The achieved density enables future work to directly load optical tweezers and create optical arrays for quantum simulation.

Real-Time Optical Biopsy of Colon Polyps With Narrow Band Imaging in Community Practice Does Not Yet Meet Key Thresholds for Clinical Decisions

PubMed Central

LADABAUM, URI; FIORITTO, ANN; MITANI, AYA; DESAI, MANISHA; KIM, JANE P.; REX, DOUGLAS K.; IMPERIALE, THOMAS; GUNARATNAM, NARESH

2017-01-01

BACKGROUND & AIMS Accurate optical analysis of colorectal polyps (optical biopsy) could prevent unnecessary polypectomies or allow a “resect and discard” strategy with surveillance intervals determined based on the results of the optical biopsy; this could be less expensive than histopathologic analysis of polyps. We prospectively evaluated real-time optical biopsy analysis of polyps with narrow band imaging (NBI) by community-based gastroenterologists. METHODS We first analyzed a computerized module to train gastroenterologists (N = 13) in optical biopsy skills using photographs of polyps. Then we evaluated a practice-based learning program for these gastroenterologists (n = 12) that included real-time optical analysis of polyps in vivo, comparison of optical biopsy predictions to histopathologic analysis, and ongoing feedback on performance. RESULTS Twelve of 13 subjects identified adenomas with >90% accuracy at the end of the computer study, and 3 of 12 subjects did so with accuracy ≥90% in the in vivo study. Learning curves showed considerable variation among batches of polyps. For diminutive rectosigmoid polyps assessed with high confidence at the end of the study, adenomas were identified with mean (95% confidence interval [CI]) accuracy, sensitivity, specificity, and negative predictive values of 81% (73%–89%), 85% (74%–96%), 78% (66%–92%), and 91% (86%–97%), respectively. The adjusted odds ratio for high confidence as a predictor of accuracy was 1.8 (95% CI, 1.3–2.5). The agreement between surveillance recommendations informed by high-confidence NBI analysis of diminutive polyps and results from histopathologic analysis of all polyps was 80% (95% CI, 77%–82%). CONCLUSIONS In an evaluation of real-time optical biopsy analysis of polyps with NBI, only 25% of gastroenterologists assessed polyps with ≥90% accuracy. The negative predictive value for identification of adenomas, but not the surveillance interval agreement, met the American Society for Gastrointestinal Endoscopy–recommended thresholds for optical biopsy. Better results in community practice must be achieved before NBI-based optical biopsy methods can be used routinely to evaluate polyps; ClinicalTrials.gov number, NCT01638091. PMID:23041328

Collection efficiency of a single optical fiber in turbid media.

PubMed

Bargo, Paulo R; Prahl, Scott A; Jacques, Steven L

2003-06-01

If a single optical fiber is used for both delivery and collection of light, two major factors affect the measurement of collected light: (1) the light transport in the medium that describes the amount of light that returns to the fiber and (2) the light coupling to the optical fiber that depends on the angular distribution of photons entering the fiber. We focus on the importance of the latter factor and describe how the efficiency of the coupling depends on the optical properties of the medium. For highly scattering tissues, the efficiency is well predicted by the numerical aperture (NA) of the fiber. For lower scattering, such as in soft tissues, photons arrive at the fiber from deeper depths, and the coupling efficiency could increase twofold to threefold above that predicted by the NA.

Modeling and testing of fast response, fiber-optic temperature sensors

NASA Astrophysics Data System (ADS)

Tonks, Michael James

The objective of this work was to design, analyze and test a fast response fiber-optic temperature probe and sensor. The sensor is intended for measuring rapid temperature changes such as produced by a blast wave formed by a detonation. This work was performed in coordination with Luna Innovations Incorporated, and the design is based on extensions of an existing fiber-optic temperature sensor developed by Luna. The sensor consists of a glass fiber with an optical wafer attached to the tip. A basic description of the principles behind the fiber-optic temperature sensor and an accompanying demodulation system is provided. For experimental validation tests, shock tubes were used to simulate the blast wave experienced at a distance of 3.0 m from the detonation of 22.7 kg of TNT. The flow conditions were predicted using idealized shock tube theory. The temperature sensors were tested in three configurations, flush at the end of the shock tube, extended on a probe 2.54 cm into the flow and extended on a probe 12.7 cm into the flow. The total temperature was expected to change from 300 K to 1130 K for the flush wall experiments and from 300 K to 960 K for the probe experiments. During the initial 0.1 milliseconds of the data the temperature only changed 8 K when the sensors were flush in the end of the shock tube. The sensor temperature changed 36 K during the same time when mounted on a probe in the flow. Schlieren pictures were taken of the flow in the shock tube to further understand the shock tube environment. Contrary to ideal shock tube theory, it was discovered that the flow did not remain stagnant in the end of the shock tube after the shock reflects from the end of the shock tube. Instead, the effects of turbulence were recorded with the fiber-optic sensors, and this turbulence was also captured in the schlieren photographs. A fast-response thermocouple was used to collect data for comparison with the fiber-optic sensor, and the fiber-optic sensor was proven to have a faster response time compared to the thermocouple. When the sensors were extended 12.7 cm into the flow, the fiber-optic sensors recorded a temperature change of 143 K compared to 38 K recorded by the thermocouple during the 0.5 millisecond test. This corresponds to 22% of the change of total temperature in the air recorded by the fiber-optic sensor and only 6% recorded by the thermocouple. Put another way, the fiber-optic sensor experience a rate of temperature change equal to 2.9x105 K/s and the thermocouple changed at a rate of 0.79x105 K/s. The data recorded from the fiber-optic sensor also contained much less noise than the thermocouple data. An unsteady finite element thermal model was created using ANSYS to predict the temperature response of the sensor. Test cases with known analytical solutions were used to verify the ANSYS modeling procedures. The shock tube flow environment was also modeled with Fluent, a commercially available CFD code. Fluent was used to determine the heat transfer between the shock tube flow and the sensor. The convection film coefficient for the flow was predicted by Fluent to be 27,150 W/m2K for the front of the wafer and 13,385 W/m2K for the side. The Fluent results were used with the ANSYS model to predict the response of the fiber-optic sensor when exposed to the shock tube flow. The results from the Fluent/ANSYS model were compared to the fiber-optic measurements taken in the shock tube. It was seen that the heat flux to the sensor was slightly over-predicted by the model, and the heat losses from the wafer were also over-predicted. Since the prediction fell within the uncertainty of the measurement, it was found to be in good agreement with the measured values. (Abstract shortened by UMI.)

Predictive analysis of thermal distribution and damage in thermotherapy on biological tissue

NASA Astrophysics Data System (ADS)

Fanjul-Vélez, Félix; Arce-Diego, José Luis

2007-05-01

The use of optical techniques is increasing the possibilities and success of medical praxis in certain cases, either in tissue characterization or treatment. Photodynamic therapy (PDT) or low intensity laser treatment (LILT) are two examples of the latter. Another very interesting implementation is thermotherapy, which consists of controlling temperature increase in a pathological biological tissue. With this method it is possible to provoke an improvement on specific diseases, but a previous analysis of treatment is needed in order for the patient not to suffer any collateral damage, an essential point due to security margins in medical procedures. In this work, a predictive analysis of thermal distribution in a biological tissue irradiated by an optical source is presented. Optical propagation is based on a RTT (Radiation Transport Theory) model solved via a numerical Monte Carlo method, in a multi-layered tissue. Data obtained are included in a bio-heat equation that models heat transference, taking into account conduction, convection, radiation, blood perfusion and vaporization depending on the specific problem. Spatial-temporal differential bio-heat equation is solved via a numerical finite difference approach. Experimental temperature distributions on animal tissue irradiated by laser radiation are shown. From thermal distribution in tissue, thermal damage is studied, based on an Arrhenius analysis, as a way of predicting harmful effects. The complete model can be used for concrete treatment proposals, as a way of predicting treatment effects and consequently decide which optical source parameters are appropriate for the specific disease, mainly wavelength and optical power, with reasonable security margins in the process.

Endoscopists can sustain high performance for the optical diagnosis of colorectal polyps following standardized and continued training.

PubMed

McGill, Sarah K; Soetikno, Roy; Rastogi, Amit; Rouse, Robert V; Sato, Tohru; Bansal, Ajay; McQuaid, Kenneth; Kaltenbach, Tonya

2015-03-01

The learning curve for optical diagnosis of colorectal polyps with the narrow-band imaging (NBI) is unknown. To forego histological analysis of diminutive polyps diagnosed optically with high confidence, guidelines recommend ≥ 90 % negative predictive value (NPV) and concordance of ≥ 90 % for surveillance intervals predicted optically and histologically. We aimed to study the learning of optical diagnosis for colorectal polyps. We studied five endoscopists as part of a randomized multisite trial comparing near-focus and standard-focus views for optical diagnosis. They trained using a computer-based module, followed by 10 real-time colonoscopies with pathology correlation. Endoscopists then optically diagnosed and resected all the polyps found during 558 consecutive colonoscopies, and diagnoses were compared with pathology. Endoscopists repeated the training module at the study midpoint. NPV and concordance of surveillance intervals for diminutive polyps diagnosed optically with high confidence were measured over time. Endoscopists showed high diagnostic performance, with a nonsignificant trend toward higher NPV in the second half of the study. For the 445 polyps in the standard-view arm, the NPV was 88.0 % (95 %CI 75.7 % - 95.5 %) in the first half and 95.8 % (88.3 % - 99.1 %) in the second; P = 0.7. Three endoscopists in the first half and four in the second achieved > 90 % NPV. Concordance of surveillance intervals was identical in the first and second halves at 98.1 % (95 %CI 93.3 % - 99.8 %). High NPV for the prediction of non-neoplasms with NBI was achieved and maintained in this group of endoscopists who participated in standardized and continued training. Both NPV and surveillance interval agreement indicated high performance in the optical diagnosis of colorectal polyps and exceeded thresholds. © Georg Thieme Verlag KG Stuttgart · New York.

Optical signal processing techniques and applications of optical phase modulation in high-speed communication systems

NASA Astrophysics Data System (ADS)

Deng, Ning

In recent years, optical phase modulation has attracted much research attention in the field of fiber optic communications. Compared with the traditional optical intensity-modulated signal, one of the main merits of the optical phase-modulated signal is the better transmission performance. For optical phase modulation, in spite of the comprehensive study of its transmission performance, only a little research has been carried out in terms of its functions, applications and signal processing for future optical networks. These issues are systematically investigated in this thesis. The research findings suggest that optical phase modulation and its signal processing can greatly facilitate flexible network functions and high bandwidth which can be enjoyed by end users. In the thesis, the most important physical-layer technology, signal processing and multiplexing, are investigated with optical phase-modulated signals. Novel and advantageous signal processing and multiplexing approaches are proposed and studied. Experimental investigations are also reported and discussed in the thesis. Optical time-division multiplexing and demultiplexing. With the ever-increasing demand on communication bandwidth, optical time division multiplexing (OTDM) is an effective approach to upgrade the capacity of each wavelength channel in current optical systems. OTDM multiplexing can be simply realized, however, the demultiplexing requires relatively complicated signal processing and stringent timing control, and thus hinders its practicability. To tackle this problem, in this thesis a new OTDM scheme with hybrid DPSK and OOK signals is proposed. Experimental investigation shows this scheme can greatly enhance the demultiplexing timing misalignment and improve the demultiplexing performance, and thus make OTDM more practical and cost effective. All-optical signal processing. In current and future optical communication systems and networks, the data rate per wavelength has been approaching the speed limitation of electronics. Thus, all-optical signal processing techniques are highly desirable to support the necessary optical switching functionalities in future ultrahigh-speed optical packet-switching networks. To cope with the wide use of optical phase-modulated signals, in the thesis, an all-optical logic for DPSK or PSK input signals is developed, for the first time. Based on four-wave mixing in semiconductor optical amplifier, the structure of the logic gate is simple, compact, and capable of supporting ultrafast operation. In addition to the general logic processing, a simple label recognition scheme, as a specific signal processing function, is proposed for phase-modulated label signals. The proposed scheme can recognize any incoming label pattern according to the local pattern, and is potentially capable of handling variable-length label patterns. Optical access network with multicast overlay and centralized light sources. In the arena of optical access networks, wavelength division multiplexing passive optical network (WDM-PON) is a promising technology to deliver high-speed data traffic. However, most of proposed WDM-PONs only support conventional point-to-point service, and cannot meet the requirement of increasing demand on broadcast and multicast service. In this thesis, a simple network upgrade is proposed based on the traditional PON architecture to support both point-to-point and multicast service. In addition, the two service signals are modulated on the same lightwave carrier. The upstream signal is also remodulated on the same carrier at the optical network unit, which can significantly relax the requirement on wavelength management at the network unit.

Optical MEMS: past, present and future

NASA Astrophysics Data System (ADS)

Ramani, Chandra Mouli

2005-09-01

Spurred by the growth of the internet, Optical Telecommunications bandwidth, experienced unprecedented growth during late 1990's. During this time of great economic expansion, the creation of new enterprises was vast and the expansion of established component, system and services companies was breathtaking. Unfortunately, this positive economic state was short-lived. This period was followed in 2001-2004 by one of the most significant market crashes in history. During those 10 years of economic growth, about $20B in venture capital was invested in the optical telecom industry, most of this investment was lost in recent years. Many start-up industries which experienced unprecedented growth at the end of the 20th century were lost at the start of the 21st. (1) During this time many, innovative technologies were born and buried. However, many new capabilities emerged from this period of unrest; one such example is the advent of Optical MEMS (MOEMS). Many academics and corporate laboratories pursued the development of MOEMS during the economic boom and, in the author's view; MOEMS surfaced as a powerful and versatile tool set that has proved invaluable and in the last few years during economic downturn, stood the test of time. In the Telecommunications industry, for optical switching and wavelength management applications MOEMS has proven to be the technology of choice. (2) Variable Optical Attenuators (VOA), Wavelength Blockers (WB), Dynamic Gain Equalizers (DGE), and most recently Wavelength Selective Switches (WSS) are being used in the numerous recent network deployments. Moreover, agile networks of the future will have MOEMS at every node. This presentation will provide an overview of the history of MOEMS in Telecommunications, discuss its byproducts and offer a window into the future of the technology.

Addressing the Future in Ancient and Modern Times.

ERIC Educational Resources Information Center

Roshwald, Mordecai

1982-01-01

Explores the similarities between ancient prophecy and modern futures prediction. The article suggests that the perceived degree of certainty in predictions of the future affects the patterns of emotional and rational responses in those receiving them. (AM)

Monitoring blood glucose changes in cutaneous tissue by temperature-modulated localized reflectance measurements.

PubMed

Yeh, Shu-Jen; Hanna, Charles F; Khalil, Omar S

2003-06-01

Most proposed noninvasive methods for glucose measurements do not consider the physiologic response of the body to changes in glucose concentration. Rather than consider the body as an inert matrix for the purpose of glucose measurement, we exploited the possibility that noninvasive measurements of glucose can be approached by investigating their effects on the skin's thermo-optical response. Glucose concentrations in humans were correlated with temperature-modulated localized reflectance signals at wavelengths between 590 and 935 nm, which do not correspond to any near-infrared glucose absorption wavelengths. Optical signal was collected while skin temperature was modulated between 22 and 38 degrees C over 2 h to generate a periodic set of cutaneous vasoconstricting and vasodilating events, as well as a periodic change in skin light scattering. The method was tested in a series of modified meal tolerance tests involving carbohydrate-rich meals and no-meal or high-protein/no-carbohydrate meals. The optical data correlated with glucose values. Changes in glucose concentrations resulting from a carbohydrate-rich meal were predicted with a model based on a carbohydrate-meal calibration run. For diabetic individuals, glucose concentrations were predicted with a standard error of prediction <1.5 mmol/L and a prediction correlation coefficient 0.73 in 80% of the cases. There were run-to-run differences in predicted glucose concentrations. Non-carbohydrate meals showed a high degree of scatter when predicted by a carbohydrate meal calibration model. Blood glucose concentrations alter thermally modulated optical signals, presumably through physiologic and physical effects. Temperature changes drive cutaneous vascular and refractive index responses in a way that mimics the effect of changes in glucose concentration. Run-to-run differences are attributable to site-to-site structural differences.

A Novel Cost-effective OFDM WDM-PON Radio Over Fiber System Employing FBG to Generate Optical mm-wave

NASA Astrophysics Data System (ADS)

Nguyen, HoangViet

2015-03-01

We have investigated and demonstrated a novel scheme to generate 2.5 Gbit/s 64 QAM orthogonal frequency division multiplexing (OFDM) signals for Radio Over Fiber (ROF) systems. We employ Fiber Bragg Grating (FBG) because the repetitive frequency of the RF source and the bandwidth of the optical modulator are largely reduced and the architecture of the ROF system is simpler. Wavelength-Division-Multiplexed Passive Optical Network (WDM-PON) has been considered as a promising solution for future broadband access networks. Principle of WDM-PON access network compatible with OFDM-ROF systems is investigated. This novel scheme which has multiple double-frequency technique to generate mm-wave signal to carry OFDM signals is a practical scheme to be applied for future broadband access networks.

Fixed Future and Uncertain Past: Theorems Explain Why It Is Often More Difficult to Reconstruct the Past Than to Predict the Future

NASA Technical Reports Server (NTRS)

Alefeld, Goetz; Koshelev, Misha; Mayer, Guenter

1997-01-01

At first glance. it may seem that reconstructing the past is, in general, easier than predicting the future, because the past has already occurred and it has already left its traces, while the future is still yet to come, and so no traces of the future are available. However, in many real life situations, including problems from geophysics and celestial mechanics, reconstructing the past is much more computationally difficult than predicting the future. In this paper, we give an explanation of this difficulty. This explanation is given both on a formal level (as a theorem) and on the informal level (as a more intuitive explanation).

Predicting the thermal/structural performance of the atmospheric trace molecules spectroscopy /ATMOS/ Fourier transform spectrometer

NASA Technical Reports Server (NTRS)

Miller, J. M.

1980-01-01

ATMOS is a Fourier transform spectrometer to measure atmospheric trace molecules over a spectral range of 2-16 microns. Assessment of the system performance of ATMOS includes evaluations of optical system errors induced by thermal and structural effects. In order to assess the optical system errors induced from thermal and structural effects, error budgets are assembled during system engineering tasks and line of sight and wavefront deformations predictions (using operational thermal and vibration environments and computer models) are subsequently compared to the error budgets. This paper discusses the thermal/structural error budgets, modelling and analysis methods used to predict thermal/structural induced errors and the comparisons that show that predictions are within the error budgets.

Optical coherence tomography in the diagnosis of dysplasia and adenocarcinoma in Barret's esophagus

NASA Astrophysics Data System (ADS)

Gladkova, N. D.; Zagaynova, E. V.; Zuccaro, G.; Kareta, M. V.; Feldchtein, F. I.; Balalaeva, I. V.; Balandina, E. B.

2007-02-01

Statistical analysis of endoscopic optical coherence tomography (EOCT) surveillance of 78 patients with Barrett's esophagus (BE) is presented in this study. The sensitivity of OCT device in retrospective open detection of early malignancy (including high grade dysplasia and intramucosal adenocarcinoma (IMAC)) was 75%, specificity 82%, diagnostic accuracy - 80%, positive predictive value- 60%, negative predictive value- 87%. In the open recognition of IMAC sensitivity was 81% and specificity were 85% each. Results of a blind recognition with the same material were similar: sensitivity - 77%, specificity 85%, diagnostic accuracy - 82%, positive predictive value- 70%, negative predictive value- 87%. As the endoscopic detection of early malignancy is problematic, OCT holds great promise in enhancing the diagnostic capability of clinical GI endoscopy.

Prediction in complex systems: The case of the international trade network

NASA Astrophysics Data System (ADS)

Vidmer, Alexandre; Zeng, An; Medo, Matúš; Zhang, Yi-Cheng

2015-10-01

Predicting the future evolution of complex systems is one of the main challenges in complexity science. Based on a current snapshot of a network, link prediction algorithms aim to predict its future evolution. We apply here link prediction algorithms to data on the international trade between countries. This data can be represented as a complex network where links connect countries with the products that they export. Link prediction techniques based on heat and mass diffusion processes are employed to obtain predictions for products exported in the future. These baseline predictions are improved using a recent metric of country fitness and product similarity. The overall best results are achieved with a newly developed metric of product similarity which takes advantage of causality in the network evolution.

Space qualification of silicon carbide for mirror applications: progress and future objectives

NASA Astrophysics Data System (ADS)

Palusinski, Iwona A.; Ghozeil, Isaac

2006-09-01

Production of optical silicon carbide (SiC) for mirror applications continues to evolve and there are renewed plans to use this material in future space-based systems. While SiC has the potential for rapid and cost-effective manufacturing of large, lightweight, athermal optical systems, this material's use in mirror applications is relatively new and has limited flight heritage. This combination of drivers stresses the necessity for a space qualification program for this material. Successful space qualification will require independent collaboration to absorb the high cost of executing this program while taking advantage of each contributing group's laboratory expertise to develop a comprehensive SiC database. This paper provides an overview of the trends and progress in the production of SiC, and identifies future objectives such as non-destructive evaluation and space-effects modeling to ensure proper implementation of this material into future space-based systems.

Combined use of SAR and optical data for environmental assessments around refugee camps in semiarid landscapes

NASA Astrophysics Data System (ADS)

Braun, A.; Hochschild, V.

2015-04-01

Over 15 million people were officially considered as refugees in the year 2012 and another 28 million as internally displaced people (IDPs). Natural disasters, climatic and environmental changes, violent regional conflicts and population growth force people to migrate in all parts of this world. This trend is likely to continue in the near future, as political instabilities increase and land degradation progresses. EO4HumEn aims at developing operational services to support humanitarian operations during crisis situations by means of dedicated geo-spatial information products derived from Earth observation and GIS data. The goal is to develop robust, automated methods of image analysis routines for population estimation, identification of potential groundwater extraction sites and monitoring the environmental impact of refugee/IDP camps. This study investigates the combination of satellite SAR data with optical sensors and elevation information for the assessment of the environmental conditions around refugee camps. In order to estimate their impact on land degradation, land cover classifications are required which target dynamic landscapes. We performed a land use / land cover classification based on a random forest algorithm and 39 input prediction rasters based on Landsat 8 data and additional layers generated from radar texture and elevation information. The overall accuracy was 92.9 %, while optical data had the highest impact on the final classification. By analysing all combinations of the three input datasets we additionally estimated their impact on single classification outcomes and land cover classes.

Radio Follow-Up of Gravitational-Wave Triggers during Advanced LIGO 01

DOE PAGES

Palliyaguru, N. T.; Corsi, Alessandra; Kasliwal, M. M.; ...

2016-09-28

We present radio follow-up observations carried out with the Karl G. Jansky Very Large Array during the first observing run (O1) of the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO). A total of three gravitational-wave triggers were followed-up during the ≈4 months of O1, from 2015 September to 2016 January. Two of these triggers, GW150914 and GW151226, are binary black hole (BH) merger events of high significance. A third trigger, G194575, was subsequently declared as an event of no interest (i.e., a false alarm). Our observations targeted selected optical transients identified by the intermediate Palomar Transient Factory in the Advanced LIGOmore » error regions of the three triggers, and a limited region of the gravitational-wave localization area of G194575 not accessible to optical telescopes due to Sun constraints, where a possible high-energy transient was identified. No plausible radio counterparts to GW150914 and GW151226 were found, in agreement with expectations for binary BH mergers. We show that combining optical and radio observations is key to identifying contaminating radio sources that may be found in the follow-up of gravitational-wave triggers, such as emission associated with star formation and active galactic nuclei. We discuss our results in the context of the theoretical predictions for radio counterparts to gravitational-wave transients, and describe our future plans for the radio follow-up of Advanced LIGO (and Virgo) triggers.« less

Spatial-spectral flexible optical networking: enabling switching solutions for a simplified and efficient SDM network platform

NASA Astrophysics Data System (ADS)

Tomkos, I.; Zakynthinos, P.; Klonidis, D.; Marom, D.; Sygletos, S.; Ellis, A.; Salvadori, E.; Siracusa, D.; Angelou, M.; Papastergiou, G.; Psaila, N.; Ferran, J. F.; Ben-Ezra, S.; Jimenez, F.; Fernández-Palacios, J. P.

2013-12-01

The traffic carried by core optical networks grows at a steady but remarkable pace of 30-40% year-over-year. Optical transmissions and networking advancements continue to satisfy the traffic requirements by delivering the content over the network infrastructure in a cost and energy efficient manner. Such core optical networks serve the information traffic demands in a dynamic way, in response to requirements for shifting of traffics demands, both temporally (day/night) and spatially (business district/residential). However as we are approaching fundamental spectral efficiency limits of singlemode fibers, the scientific community is pursuing recently the development of an innovative, all-optical network architecture introducing the spatial degree of freedom when designing/operating future transport networks. Spacedivision- multiplexing through the use of bundled single mode fibers, and/or multi-core fibers and/or few-mode fibers can offer up to 100-fold capacity increase in future optical networks. The EU INSPACE project is working on the development of a complete spatial-spectral flexible optical networking solution, offering the network ultra-high capacity, flexibility and energy efficiency required to meet the challenges of delivering exponentially growing traffic demands in the internet over the next twenty years. In this paper we will present the motivation and main research activities of the INSPACE consortium towards the realization of the overall project solution.

Cultural variation in the use of current life satisfaction to predict the future.

PubMed

Oishi, S; Wyer, R S; Colcombe, S J

2000-03-01

Three studies examined cultural and situational influences on the tendency for people to use their current life satisfaction to predict future life events. On the basis of the self-enhancement literature, it was predicted that either writing about a positive personal experience or reading about another's negative experience would lead European Americans to focus their attention on internal attributes and thus would lead them to use their current life satisfaction in predicting the future. Conversely, on the basis of the self-criticism literature, it was predicted that these same conditions would lead Asian Americans to focus their attention on external factors and, therefore, would decrease their likelihood of using their current life satisfaction to predict the future. Studies 1 and 2 supported these hypotheses. Study 3 showed that these patterns could be obtained by subliminally priming concepts associated with individualism and collectivism.

The Next Twenty-Five Years: It's Time to Plan.

ERIC Educational Resources Information Center

Jugenheimer, Donald W.

There is a need in the advertising industry for prediction--of the future in general, of the new communication technology, and of the implications for advertising. Studies of the future in other disciplines have identified at least four separate future trends relevant to prediction and preparation for the future in advertising: within specified…

The Optical Gravitational Lensing Experiment

NASA Technical Reports Server (NTRS)

Udalski, A.; Szymanski, M.; Kaluzny, J.; Kubiak, M.; Mateo, Mario

1992-01-01

The technical features are described of the Optical Gravitational Lensing Experiment, which aims to detect a statistically significant number of microlensing events toward the Galactic bulge. Clusters of galaxies observed during the 1992 season are listed and discussed and the reduction methods are described. Future plans are addressed.

The OPTICON technology roadmap for optical and infrared astronomy

NASA Astrophysics Data System (ADS)

Cunningham, Colin; Melotte, David; Molster, Frank

2010-07-01

The Key Technology Network (KTN) within the OPTICON programme has been developing a roadmap for the technology needed to meet the challenges of optical and infrared astronomy over the next few years, with particular emphasis on the requirements of Extremely Large Telescopes. The process and methodology so far will be described, along with the most recent roadmap. The roadmap shows the expected progression of ground-based astronomy facilities and the technological developments which will be required to realise these new facilities. The roadmap highlights the key stages in the development of these technologies. In some areas, such as conventional optics, gradual developments in areas such as light-weighting of optics will slowly be adopted into future instruments. In other areas, such as large area IR detectors, more rapid progress can be expected as new processing techniques allow larger and faster arrays. Finally, other areas such as integrated photonics have the potential to revolutionise astronomical instrumentation. Future plans are outlined, in particular our intention to look at longer term development and disruptive technologies.

MEMS-based beam-steerable free-space optical communication link for reconfigurable wireless data center

NASA Astrophysics Data System (ADS)

Deng, Peng; Kavehrad, Mohsen; Lou, Yan

2017-01-01

Flexible wireless datacenter networks based on free space optical communication (FSO) links are being considered as promising solutions to meet the future datacenter demands of high throughput, robustness to dynamic traffic patterns, cabling complexity and energy efficiency. Robust and precise steerable FSO links over dynamic traffic play a key role in the reconfigurable optical wireless datacenter inter-rack network. In this work, we propose and demonstrate a reconfigurable 10Gbps FSO system incorporated with smart beam acquisition and tracking mechanism based on gimballess two-axis MEMS micro-mirror and retro-reflective film marked aperture. The fast MEMS-based beam acquisition switches laser beam of FSO terminal from one rack to the next for reconfigurable networks, and the precise beam tracking makes FSO device auto-correct the misalignment in real-time. We evaluate the optical power loss and bit error rate performance of steerable FSO links at various directions. Experimental results suggest that the MEMS based beam steerable FSO links hold considerable promise for the future reconfigurable wireless datacenter networks.

The future of quantum dots in drug discovery.

PubMed

Lin, Guimiao; Yin, Feng; Yong, Ken-Tye

2014-09-01

The rapid development of drug discovery today is inseparable from the interaction of advanced particle technologies and new drug synthesis protocols. Quantum dots (QDs) are regarded as a unique class of fluorescent labels, with unique optical properties such as high brightness and long-term colloidal and optical stability; these are suitable for optical imaging, drug delivery and optical tracking, fluorescence immunoassay and other medicinal applications. More importantly, QD possesses a rich surface chemistry property that is useful for incorporating various drug molecules, targeting ligands, and additional contrast agents (e.g., MRI, PET, etc.) onto the nanoparticle surface for achieving targeted and traceable drug delivery therapy at both cellular and systemic levels. In recent times, the advancement of QD technology has promoted the use of functionalized nanocrystals for in vivo applications. Such research is paving the way for drug discovery using various bioconjugated QD formulations. In this editorial, the authors highlight the current research progress and future applications of QDs in drug discovery.

X-ray pore optic developments

NASA Astrophysics Data System (ADS)

Wallace, Kotska; Bavdaz, Marcos; Collon, Maximilien; Beijersbergen, Marco; Kraft, Stefan; Fairbend, Ray; Séguy, Julien; Blanquer, Pascal; Graue, Roland; Kampf, Dirk

2017-11-01

In support of future x-ray telescopes ESA is developing new optics for the x-ray regime. To date, mass and volume have made x-ray imaging technology prohibitive to planetary remote sensing imaging missions. And although highly successful, the mirror technology used on ESA's XMM-Newton is not sufficient for future, large, x-ray observatories, since physical limits on the mirror packing density mean that aperture size becomes prohibitive. To reduce telescope mass and volume the packing density of mirror shells must be reduced, whilst maintaining alignment and rigidity. Structures can also benefit from a modular optic arrangement. Pore optics are shown to meet these requirements. This paper will discuss two pore optic technologies under development, with examples of results from measurement campaigns on samples. One activity has centred on the use of coated, silicon wafers, patterned with ribs, that are integrated onto a mandrel whose form has been polished to the required shape. The wafers follow the shape precisely, forming pore sizes in the sub-mm region. Individual stacks of mirrors can be manufactured without risk to, or dependency on, each other and aligned in a structure from which they can also be removed without hazard. A breadboard is currently being built to demonstrate this technology. A second activity centres on glass pore optics. However an adaptation of micro channel plate technology to form square pores has resulted in a monolithic material that can be slumped into an optic form. Alignment and coating of two such plates produces an x-ray focusing optic. A breadboard 20cm aperture optic is currently being built.

Adaptive optics scanning laser ophthalmoscopy in fundus imaging, a review and update.

PubMed

Zhang, Bing; Li, Ni; Kang, Jie; He, Yi; Chen, Xiao-Ming

2017-01-01

Adaptive optics scanning laser ophthalmoscopy (AO-SLO) has been a promising technique in funds imaging with growing popularity. This review firstly gives a brief history of adaptive optics (AO) and AO-SLO. Then it compares AO-SLO with conventional imaging methods (fundus fluorescein angiography, fundus autofluorescence, indocyanine green angiography and optical coherence tomography) and other AO techniques (adaptive optics flood-illumination ophthalmoscopy and adaptive optics optical coherence tomography). Furthermore, an update of current research situation in AO-SLO is made based on different fundus structures as photoreceptors (cones and rods), fundus vessels, retinal pigment epithelium layer, retinal nerve fiber layer, ganglion cell layer and lamina cribrosa. Finally, this review indicates possible research directions of AO-SLO in future.

Figuring large optics at the sub-nanometer level: compensation for coating and gravity distortions.

PubMed

Gensemer, Stephen; Gross, Mark

2015-11-30

Large, precision optics can now be manufactured with surface figures specified at the sub-nanometer level. However, coatings and gravity deform large optics, and there are limits to what can be corrected by clever compensation. Instead, deformations caused by stress from optical mounts and deposited coatings must be incorporated into the optical design. We demonstrate compensation of coating stress on a 370mm substrate to λ/200 by a process of coating and annealing. We also model the same process and identify the leading effects that must be anticipated in fabrication of optics for future gravitational wave detectors and other applications of large, precisely figured optics, and identify the limitations inherent in using coatings to compensate for these deformations.

Adaptive optics scanning laser ophthalmoscopy in fundus imaging, a review and update

PubMed Central

Zhang, Bing; Li, Ni; Kang, Jie; He, Yi; Chen, Xiao-Ming

2017-01-01

Adaptive optics scanning laser ophthalmoscopy (AO-SLO) has been a promising technique in funds imaging with growing popularity. This review firstly gives a brief history of adaptive optics (AO) and AO-SLO. Then it compares AO-SLO with conventional imaging methods (fundus fluorescein angiography, fundus autofluorescence, indocyanine green angiography and optical coherence tomography) and other AO techniques (adaptive optics flood-illumination ophthalmoscopy and adaptive optics optical coherence tomography). Furthermore, an update of current research situation in AO-SLO is made based on different fundus structures as photoreceptors (cones and rods), fundus vessels, retinal pigment epithelium layer, retinal nerve fiber layer, ganglion cell layer and lamina cribrosa. Finally, this review indicates possible research directions of AO-SLO in future. PMID:29181321

CHRONICLE: Third International Symposium on Modern Optics, Budapest, September 1988

NASA Astrophysics Data System (ADS)

Bukhenskiĭ, M. F.; Nikitin, P. I.; Semenov, A. S.

1989-07-01

The Third International Symposium on Modern Optics (Optics-88), held in Budapest on 13-16 September 1988, was organized by the Hungarian Optical, Acoustic, and Cinematographic Society with the support of the International Commission on Optics and various scientific and industrial organizations in Hungary. The International Symposium Committee was composed of leading specialists from 11 countries in Asia, America, and Europe with A. M. Prokhorov (USSR) and N. Kroo (Hungary) as Co-chairmen. The purpose of this regular symposium is to summarize the scientific and technical progress underlying the developments in optics itself, discuss the branches of science where progress depends on optical methods in devices, and draw the attention of specialists to the most promising trends which should yield results in the immediate future.

Combining a Spatial Model and Demand Forecasts to Map Future Surface Coal Mining in Appalachia

PubMed Central

Strager, Michael P.; Strager, Jacquelyn M.; Evans, Jeffrey S.; Dunscomb, Judy K.; Kreps, Brad J.; Maxwell, Aaron E.

2015-01-01

Predicting the locations of future surface coal mining in Appalachia is challenging for a number of reasons. Economic and regulatory factors impact the coal mining industry and forecasts of future coal production do not specifically predict changes in location of future coal production. With the potential environmental impacts from surface coal mining, prediction of the location of future activity would be valuable to decision makers. The goal of this study was to provide a method for predicting future surface coal mining extents under changing economic and regulatory forecasts through the year 2035. This was accomplished by integrating a spatial model with production demand forecasts to predict (1 km2) gridded cell size land cover change. Combining these two inputs was possible with a ratio which linked coal extraction quantities to a unit area extent. The result was a spatial distribution of probabilities allocated over forecasted demand for the Appalachian region including northern, central, southern, and eastern Illinois coal regions. The results can be used to better plan for land use alterations and potential cumulative impacts. PMID:26090883

Predicting past and future diameter growth for trees in the northeastern United States

Treesearch

James A. Westfall

2006-01-01

Tree diameter growth models are widely used in forestry applications, often to predict tree size at a future point in time. Also, there are instances where projections of past diameters are needed. A relative diameter growth model was developed to allow prediction of both future and past growth rates. Coefficients were estimated for 15 species groups that cover most...

IMF Prediction with Cosmic Rays

NASA Astrophysics Data System (ADS)

Bieber, J. W.; Evenson, P. A.; Kuwabara, T.; Pei, C.

2013-12-01

Cosmic rays impacting Earth have passed through and interacted with the interplanetary magnetic field (IMF) surrounding Earth, and in some sense they carry information on the three-dimensional structure of that field. This work uses neutron monitor data in an effort to extract that information and use it to predict the future behavior of the IMF, especially the north-south component (Bz) which is so crucial in determining geomagnetic activity. We consider 161 events from a published list of interplanetary coronal mass ejections and compare hourly averages of the predicted field with the actual field measured later. We find that the percentage of events with 'good' predictions of Bz (in the sense of having a positive correlation between the prediction and the subsequent measurement) varies from about 85% for predictions 1 hour into the future to about 60% for predictions 4 hours into the future. We present several ideas for how the method might be improved in future implementations. Supported by NASA grant NNX08AQ01G and NSF grant ANT-0739620.

Single mode variable-sensitivity fiber optic sensors

NASA Technical Reports Server (NTRS)

Murphy, K. A.; Fogg, B. R.; Gunther, M. F.; Claus, R. O.

1992-01-01

We review spatially-weighted optical fiber sensors that filter specific vibration modes from one dimensional beams placed in clamped-free and clamped-clamped configurations. The sensitivity of the sensor is varied along the length of the fiber by tapering circular-core, dual-mode optical fibers. Selective vibration mode suppression on the order of 10 dB was obtained. We describe experimental results and propose future extensions to single mode sensor applications.

Coherent Optical Communications: Historical Perspectives and Future Directions

NASA Astrophysics Data System (ADS)

Kikuchi, Kazuro

Coherent optical fiber communications were studied extensively in the 1980s mainly because high sensitivity of coherent receivers could elongate the unrepeated transmission distance; however, their research and development have been interrupted for nearly 20 years behind the rapid progress in high-capacity wavelength-division multiplexed (WDM) systems using erbium-doped fiber amplifiers (EDFAs). In 2005, the demonstration of digital carrier phase estimation in coherent receivers has stimulated a widespread interest in coherent optical communications again. This is due to the fact that the digital coherent receiver enables us to employ a variety of spectrally efficient modulation formats such as M-ary phase-shift keying (PSK) and quadrature amplitude modulation (QAM) without relying upon a rather complicated optical phase-locked loop. In addition, since the phase information is preserved after detection, we can realize electrical post-processing functions such as compensation for chromatic dispersion and polarization-mode dispersion in the digital domain. These advantages of the born-again coherent receiver have enormous potential for innovating existing optical communication systems. In this chapter, after reviewing the 20-year history of coherent optical communication systems, we describe the principle of operation of coherent detection, the concept of the digital coherent receiver, and its performance evaluation. Finally, challenges for the future are summarized.

Optical Fiber Distributed Sensing Structural Health Monitoring (SHM) Strain Measurements Taken During Cryotank Y-Joint Test Article Load Cycling at Liquid Helium Temperatures

NASA Technical Reports Server (NTRS)

Allison, Sidney G.; Prosser, William H.; Hare, David A.; Moore, Thomas C.; Kenner, Winfred S.

2007-01-01

This paper outlines cryogenic Y-joint testing at Langley Research Center (LaRC) to validate the performance of optical fiber Bragg grating strain sensors for measuring strain at liquid helium temperature (-240 C). This testing also verified survivability of fiber sensors after experiencing 10 thermal cool-down, warm-up cycles and 400 limit load cycles. Graphite composite skins bonded to a honeycomb substrate in a sandwich configuration comprised the Y-joint specimens. To enable SHM of composite cryotanks for consideration to future spacecraft, a light-weight, durable monitoring technology is needed. The fiber optic distributed Bragg grating strain sensing system developed at LaRC is a viable substitute for conventional strain gauges which are not practical for SHM. This distributed sensing technology uses an Optical Frequency Domain Reflectometer (OFDR). This measurement approach has the advantage that it can measure hundreds of Bragg grating sensors per fiber and the sensors are all written at one frequency, greatly simplifying fiber manufacturing. Fiber optic strain measurements compared well to conventional strain gauge measurements obtained during these tests. These results demonstrated a high potential for a successful implementation of a SHM system incorporating LaRC's fiber optic sensing system on the composite cryotank and other future cryogenic applications.

High-speed laser communications in UAV scenarios

NASA Astrophysics Data System (ADS)

Griethe, Wolfgang; Gregory, Mark; Heine, Frank; Kämpfner, Hartmut

2011-05-01

Optical links, based on coherent homodyne detection and BPSK modulation with bidirectional data transmission of 5.6 Gbps over distances of about 5,000 km and BER of 10-8, have been sufficiently verified in space. The verification results show that this technology is suitable not only for space applications but also for applications in the troposphere. After a brief description of the Laser Communication Terminal (LCT) for space applications, the paper consequently discusses the future utilization of satellite-based optical data links for Beyond Line of Sight (BLOS) operations of High Altitude Long Endurance (HALE) Unmanned Aerial Vehicles (UAV). It is shown that the use of optical frequencies is the only logical consequence of an ever-increasing demand for bandwidth. In terms of Network Centric Warfare it is highly recommended that Unmanned Aircraft Systems (UAS) of the future should incorporate that technology which allows almost unlimited bandwidth. The advantages of optical communications especially for Intelligence, Surveillance and Reconnaissance (ISR) are underlined. Moreover, the preliminary design concept of an airborne laser communication terminal is described. Since optical bi-directional links have been tested between a LCT in space and a TESAT Optical Ground Station (OGS), preliminary analysis on tracking and BER performance and the impact of atmospheric disturbances on coherent links will be presented.

Understanding Alterations in Cell Nano-architecture during Early Carcinogenesis using Optical Microscopy

NASA Astrophysics Data System (ADS)

Damania, Dhwanil

Carcinogenesis is a complex multi-step process which eventually results in a malignant phenotype that often progresses into a fatal metastatic stage. There are several molecular changes (e.g. DNA methylation, activation of proto-oncogenes, loss of tumor-suppressor genes, histone acetylation) that occur in cells prior to the microscopically detectable morphological alterations. Hence, it is intuitive that these molecular changes should impact various biochemical, biophysical and transport processes within the cell and therefore its nanoscale morphology. Furthermore, recent studies have established that apparently `normal' cells (i.e., away from the actual tumor location) undergo similar genetic/epigenetic changes as the actual cancer cells, giving rise to the phenomenon of field carcinogenesis. Unfortunately, traditional microscopy or histopathology cannot resolve structures below 300 nm due to diffraction-limited resolution. Hence, we developed a novel optical imaging technique, partial wave spectroscopic (PWS) microscopy or optical nanocytology which quantifies the nanoscale refractive-index fluctuations (i.e. mass-density variations such as chromatin compaction) in an optically measured biomarker, disorder strength (Ld). This dissertation proves the nanoscale sensitivity of PWS nanocytology and shows that increase in Ld parallels neoplastic potential of a cell by using standardized cell-lines and animal-models. Based on concept of field carcinogenesis, we employ PWS nanocytology in a multi-center clinical study on approximately 450 patients in four different cancer-types (colon, ovarian, thyroid and lung) and we illustrate that nanoscale disorder increase is a ubiquitous phenomenon across different organs. We further demonstrate the potential of PWS nanocytology in predicting risk for developing future neoplasia. Biologically, we prove that cytoskeletal organization in both nucleus and cytoplasm plays a crucial role in governing L d-differences. Moreover, we elucidate the role of chromatin architecture (specifically histone deacetylase2) in determining nanoscale nuclear disorder. Finally, we develop an image-analysis technique to extract native 3-dimensional-mass-density correlation function of biological cells (cheek cells) using scanning transmission electron microscopy (STEM) without staining or sectioning. This technique can be used in future to corroborate PWS results. Overall, this work signifies the potential of PWS nanocytology in a clinical setting and establishes it as an important minimally-invasive tool for early cancer detection as well as for better biological understanding of a disease.

Drive to miniaturization: integrated optical networks on mobile platforms

NASA Astrophysics Data System (ADS)

Salour, Michael M.; Batayneh, Marwan; Figueroa, Luis

2011-11-01

With rapid growth of the Internet, bandwidth demand for data traffic is continuing to explode. In addition, emerging and future applications are becoming more and more network centric. With the proliferation of data communication platforms and data-intensive applications (e.g. cloud computing), high-bandwidth materials such as video clips dominating the Internet, and social networking tools, a networking technology is very desirable which can scale the Internet's capability (particularly its bandwidth) by two to three orders of magnitude. As the limits of Moore's law are approached, optical mesh networks based on wavelength-division multiplexing (WDM) have the ability to satisfy the large- and scalable-bandwidth requirements of our future backbone telecommunication networks. In addition, this trend is also affecting other special-purpose systems in applications such as mobile platforms, automobiles, aircraft, ships, tanks, and micro unmanned air vehicles (UAVs) which are becoming independent systems roaming the sky while sensing data, processing, making decisions, and even communicating and networking with other heterogeneous systems. Recently, WDM optical technologies have seen advances in its transmission speeds, switching technologies, routing protocols, and control systems. Such advances have made WDM optical technology an appealing choice for the design of future Internet architectures. Along these lines, scientists across the entire spectrum of the network architectures from physical layer to applications have been working on developing devices and communication protocols which can take full advantage of the rapid advances in WDM technology. Nevertheless, the focus has always been on large-scale telecommunication networks that span hundreds and even thousands of miles. Given these advances, we investigate the vision and applicability of integrating the traditionally large-scale WDM optical networks into miniaturized mobile platforms such as UAVs. We explain the benefits of WDM optical technology for these applications. We also describe some of the limitations of WDM optical networks as the size of a vehicle gets smaller, such as in micro-UAVs, and study the miniaturization and communication system limitations in such environments.

Characterization of Material Response During Arc-Jet Testing with Optical Methods Status and Perspectives

NASA Technical Reports Server (NTRS)

Winter, Michael

2012-01-01

The characterization of ablation and recession of heat shield materials during arc jet testing is an important step towards understanding the governing processes during these tests and therefore for a successful extrapolation of ground test data to flight. The behavior of ablative heat shield materials in a ground-based arc jet facility is usually monitored through measurement of temperature distributions (across the surface and in-depth), and through measurement of the final surface recession. These measurements are then used to calibrate/validate materials thermal response codes, which have mathematical models with reasonably good fidelity to the physics and chemistry of ablation, and codes thus calibrated are used for predicting material behavior in flight environments. However, these thermal measurements only indirectly characterize the pyrolysis processes within an ablative material pyrolysis is the main effect during ablation. Quantification of pyrolysis chemistry would therefore provide more definitive and useful data for validation of the material response codes. Information of the chemical products of ablation, to various levels of detail, can be obtained using optical methods. Suitable optical methods to measure the shape and composition of these layers (with emphasis on the blowing layer) during arc jet testing are: 1) optical emission spectroscopy (OES) 2) filtered imaging 3) laser induced fluorescence (LIF) and 4) absorption spectroscopy. Several attempts have been made to optically measure the material response of ablative materials during arc-jet testing. Most recently, NH and OH have been identified in the boundary layer of a PICA ablator. These species are suitable candidates for a detection through PLIF which would enable a spatially-resolved characterization of the blowing layer in terms of both its shape and composition. The recent emission spectroscopy data will be presented and future experiments for a qualitative and quantitative characterization of the material response of ablative materials during arc-jet testing will be discussed.

Stress Optical Coefficient, Test Methodology, and Glass Standard Evaluation

DTIC Science & Technology

2016-05-01

identifying and mapping flaw size distributions on glass surfaces for predicting mechanical response. International Journal of Applied Glass ...ARL-TN-0756 ● MAY 2016 US Army Research Laboratory Stress Optical Coefficient, Test Methodology, and Glass Standard Evaluation...Stress Optical Coefficient, Test Methodology, and Glass Standard Evaluation by Clayton M Weiss Oak Ridge Institute for Science and Education

Longitudinally Jointed Edge-Wise Compression HoneyComb Composite Sandwich Coupon Testing And Fe Analysis: Three Methods of Strain Measurement, And Comparison

NASA Technical Reports Server (NTRS)

Farrokh, Babak; Rahim, Nur Aida Abul; Segal, Ken; Fan, Terry; Jones, Justin; Hodges, Ken; Mashni, Noah; Garg, Naman; Sang, Alex

2013-01-01

Three distinct strain measurement methods (i.e., foil resistance strain gages, fiber optic strain sensors, and a three-dimensional digital image photogrammetry that gives full field strain and displacement measurements) were implemented to measure strains on the back and front surfaces of a longitudinally jointed curved test article subjected to edge-wise compression testing, at NASA Goddard Space Flight Center, according to ASTM C364. The pre-test finite element analysis (FEA) was conducted to assess ultimate failure load and predict strain distribution pattern throughout the test coupon. The predicted strain pattern contours were then utilized as guidelines for installing the strain measurement instrumentations. The foil resistance strain gages and fiber optic strain sensors were bonded on the specimen at locations with nearly the same analytically predicted strain values, and as close as possible to each other, so that, comparisons between the measured strains by strain gages and fiber optic sensors, as well as the three-dimensional digital image photogrammetric system are relevant. The test article was loaded to failure (at 167 kN), at the compressive strain value of 10,000 micro epsilon. As a part of this study, the validity of the measured strains by fiber optic sensors is examined against the foil resistance strain gages and the three-dimensional digital image photogrammetric data, and comprehensive comparisons are made with FEA predictions.

Optimal Performance Monitoring of Hybrid Mid-Infrared Wavelength MIMO Free Space Optical and RF Wireless Networks in Fading Channels

NASA Astrophysics Data System (ADS)

Schmidt, Barnet Michael

An optimal performance monitoring metric for a hybrid free space optical and radio-frequency (RF) wireless network, the Outage Capacity Objective Function, is analytically developed and studied. Current and traditional methods of performance monitoring of both optical and RF wireless networks are centered on measurement of physical layer parameters, the most common being signal-to-noise ratio, error rate, Q factor, and eye diagrams, occasionally combined with link-layer measurements such as data throughput, retransmission rate, and/or lost packet rate. Network management systems frequently attempt to predict or forestall network failures by observing degradations of these parameters and to attempt mitigation (such as offloading traffic, increasing transmitter power, reducing the data rate, or combinations thereof) prior to the failure. These methods are limited by the frequent low sensitivity of the physical layer parameters to the atmospheric optical conditions (measured by optical signal-to-noise ratio) and the radio frequency fading channel conditions (measured by signal-to-interference ratio). As a result of low sensitivity, measurements of this type frequently are unable to predict impending failures sufficiently in advance for the network management system to take corrective action prior to the failure. We derive and apply an optimal measure of hybrid network performance based on the outage capacity of the hybrid optical and RF channel, the outage capacity objective function. The objective function provides high sensitivity and reliable failure prediction, and considers both the effects of atmospheric optical impairments on the performance of the free space optical segment as well as the effect of RF channel impairments on the radio frequency segment. The radio frequency segment analysis considers the three most common RF channel fading statistics: Rayleigh, Ricean, and Nakagami-m. The novel application of information theory to the underlying physics of the gamma-gamma optical channel and radio fading channels in determining the joint hybrid channel outage capacity provides the best performance estimate under any given set of operating conditions. It is shown that, unlike traditional physical layer performance monitoring techniques, the objective function based upon the outage capacity of the hybrid channel at any combination of OSNR and SIR, is able to predict channel degradation and failure well in advance of the actual outage. An outage in the information-theoretic definition occurs when the offered load exceeds the outage capacity under the current conditions of OSNR and SIR. The optical channel is operated at the "long" mid-infrared wavelength of 10000 nm. which provides improved resistance to scattering compared to shorter wavelengths such as 1550 nm.

Measurements of resonant scattering in the Perseus Cluster core with Hitomi SXS

NASA Astrophysics Data System (ADS)

Hitomi Collaboration; Aharonian, Felix; Akamatsu, Hiroki; Akimoto, Fumie; Allen, Steven W.; Angelini, Lorella; Audard, Marc; Awaki, Hisamitsu; Axelsson, Magnus; Bamba, Aya; Bautz, Marshall W.; Blandford, Roger; Brenneman, Laura W.; Brown, Gregory V.; Bulbul, Esra; Cackett, Edward M.; Chernyakova, Maria; Chiao, Meng P.; Coppi, Paolo S.; Costantini, Elisa; de Plaa, Jelle; de Vries, Cor P.; den Herder, Jan-Willem; Done, Chris; Dotani, Tadayasu; Ebisawa, Ken; Eckart, Megan E.; Enoto, Teruaki; Ezoe, Yuichiro; Fabian, Andrew C.; Ferrigno, Carlo; Foster, Adam R.; Fujimoto, Ryuichi; Fukazawa, Yasushi; Furukawa, Maki; Furuzawa, Akihiro; Galeazzi, Massimiliano; Gallo, Luigi C.; Gandhi, Poshak; Giustini, Margherita; Goldwurm, Andrea; Gu, Liyi; Guainazzi, Matteo; Haba, Yoshito; Hagino, Kouichi; Hamaguchi, Kenji; Harrus, Ilana M.; Hatsukade, Isamu; Hayashi, Katsuhiro; Hayashi, Takayuki; Hayashida, Kiyoshi; Hiraga, Junko S.; Hornschemeier, Ann; Hoshino, Akio; Hughes, John P.; Ichinohe, Yuto; Iizuka, Ryo; Inoue, Hajime; Inoue, Yoshiyuki; Ishida, Manabu; Ishikawa, Kumi; Ishisaki, Yoshitaka; Iwai, Masachika; Kaastra, Jelle; Kallman, Tim; Kamae, Tsuneyoshi; Kataoka, Jun; Katsuda, Satoru; Kawai, Nobuyuki; Kelley, Richard L.; Kilbourne, Caroline A.; Kitaguchi, Takao; Kitamoto, Shunji; Kitayama, Tetsu; Kohmura, Takayoshi; Kokubun, Motohide; Koyama, Katsuji; Koyama, Shu; Kretschmar, Peter; Krimm, Hans A.; Kubota, Aya; Kunieda, Hideyo; Laurent, Philippe; Lee, Shiu-Hang; Leutenegger, Maurice A.; Limousin, Olivier O.; Loewenstein, Michael; Long, Knox S.; Lumb, David; Madejski, Greg; Maeda, Yoshitomo; Maier, Daniel; Makishima, Kazuo; Markevitch, Maxim; Matsumoto, Hironori; Matsushita, Kyoko; McCammon, Dan; McNamara, Brian R.; Mehdipour, Missagh; Miller, Eric D.; Miller, Jon M.; Mineshige, Shin; Mitsuda, Kazuhisa; Mitsuishi, Ikuyuki; Miyazawa, Takuya; Mizuno, Tsunefumi; Mori, Hideyuki; Mori, Koji; Mukai, Koji; Murakami, Hiroshi; Mushotzky, Richard F.; Nakagawa, Takao; Nakajima, Hiroshi; Nakamori, Takeshi; Nakashima, Shinya; Nakazawa, Kazuhiro; Nobukawa, Kumiko K.; Nobukawa, Masayoshi; Noda, Hirofumi; Odaka, Hirokazu; Ogorzalek, Anna; Ohashi, Takaya; Ohno, Masanori; Okajima, Takashi; Ota, Naomi; Ozaki, Masanobu; Paerels, Frits; Paltani, Stéphane; Petre, Robert; Pinto, Ciro; Porter, Frederick S.; Pottschmidt, Katja; Reynolds, Christopher S.; Safi-Harb, Samar; Saito, Shinya; Sakai, Kazuhiro; Sasaki, Toru; Sato, Goro; Sato, Kosuke; Sato, Rie; Sawada, Makoto; Schartel, Norbert; Serlemtsos, Peter J.; Seta, Hiromi; Shidatsu, Megumi; Simionescu, Aurora; Smith, Randall K.; Soong, Yang; Stawarz, Łukasz; Sugawara, Yasuharu; Sugita, Satoshi; Szymkowiak, Andrew; Tajima, Hiroyasu; Takahashi, Hiromitsu; Takahashi, Tadayuki; Takeda, Shiníchiro; Takei, Yoh; Tamagawa, Toru; Tamura, Takayuki; Tanaka, Takaaki; Tanaka, Yasuo; Tanaka, Yasuyuki T.; Tashiro, Makoto S.; Tawara, Yuzuru; Terada, Yukikatsu; Terashima, Yuichi; Tombesi, Francesco; Tomida, Hiroshi; Tsuboi, Yohko; Tsujimoto, Masahiro; Tsunemi, Hiroshi; Tsuru, Takeshi Go; Uchida, Hiroyuki; Uchiyama, Hideki; Uchiyama, Yasunobu; Ueda, Shutaro; Ueda, Yoshihiro; Uno, Shiníchiro; Urry, C. Megan; Ursino, Eugenio; Watanabe, Shin; Werner, Norbert; Wilkins, Dan R.; Williams, Brian J.; Yamada, Shinya; Yamaguchi, Hiroya; Yamaoka, Kazutaka; Yamasaki, Noriko Y.; Yamauchi, Makoto; Yamauchi, Shigeo; Yaqoob, Tahir; Yatsu, Yoichi; Yonetoku, Daisuke; Zhuravleva, Irina; Zoghbi, Abderahmen

2018-03-01

Thanks to its high spectral resolution (˜5 eV at 6 keV), the Soft X-ray Spectrometer (SXS) on board Hitomi enables us to measure the detailed structure of spatially resolved emission lines from highly ionized ions in galaxy clusters for the first time. In this series of papers, using the SXS we have measured the velocities of gas motions, metallicities and the multi-temperature structure of the gas in the core of the Perseus Cluster. Here, we show that when inferring physical properties from line emissivities in systems like Perseus, the resonant scattering effect should be taken into account. In the Hitomi waveband, resonant scattering mostly affects the Fe XXV Heα line (w)—the strongest line in the spectrum. The flux measured by Hitomi in this line is suppressed by a factor of ˜1.3 in the inner ˜30 kpc, compared to predictions for an optically thin plasma; the suppression decreases with the distance from the center. The w line also appears slightly broader than other lines from the same ion. The observed distortions of the w line flux, shape, and distance dependence are all consistent with the expected effect of the resonant scattering in the Perseus core. By measuring the ratio of fluxes in optically thick (w) and thin (Fe XXV forbidden, Heβ, Lyα) lines, and comparing these ratios with predictions from Monte Carlo radiative transfer simulations, the velocities of gas motions have been obtained. The results are consistent with the direct measurements of gas velocities from line broadening described elsewhere in this series, although the systematic and statistical uncertainties remain significant. Further improvements in the predictions of line emissivities in plasma models, and deeper observations with future X-ray missions offering similar or better capabilities to the Hitomi SXS, will enable resonant scattering measurements to provide powerful constraints on the amplitude and anisotropy of cluster gas motions.

Results of Kirari optical communication demonstration experiments with NICT optical ground station (KODEN) aiming for future classical and quantum communications in space

NASA Astrophysics Data System (ADS)

Toyoshima, Morio; Takenaka, Hideki; Shoji, Yozo; Takayama, Yoshihisa; Koyama, Yoshisada; Kunimori, Hiroo

2012-05-01

Bi-directional ground-to-satellite laser communication experiments were successfully performed between the optical ground station developed by the National Institute of Information and Communications Technology (NICT), located in Koganei City in suburban Tokyo, and a low earth orbit (LEO) satellite, the "Kirari" Optical Inter-orbit Communications Engineering Test Satellite (OICETS). The experiments were conducted in cooperation with the Japan Aerospace Exploration Agency (JAXA), and called the Kirari Optical communication Demonstration Experiments with the NICT optical ground station (or KODEN). The ground-to-OICETS laser communication experiment was the first in-orbit demonstration involving the LEO satellite. The laser communication experiment was conducted since March 2006. The polarization characteristics of an artificial laser source in space, such as Stokes parameters, and the degree of polarization were measured through space-to-ground atmospheric transmission paths, which results contribute to the link estimation for quantum key distribution via space and provide the potential for enhancements in quantum cryptography on a global scale in the future. The Phase-5 experiment, international laser communications experiments were also successfully conducted with four optical ground stations located in the United States, Spain, Germany, and Japan from April 2009 to September 2009. The purpose of the Phase-5 experiment was to establish OICETS-to-ground laser communication links from the different optical ground stations and the statistical analyses such as the normalized power, scintillation index, probability density function, auto-covariance function, and power spectral density were performed. Thus the applicability of the satellite laser communications was demonstrated, aiming not only for geostationary earth orbit-LEO links but also for ground-to-LEO optical links. This paper presents the results of the KODEN experiments and mainly introduces the common analyses among the different optical ground stations.

Incorporating population viability models into species status assessment and listing decisions under the U.S. Endangered Species Act

USGS Publications Warehouse

McGowan, Conor P.; Allan, Nathan; Servoss, Jeff; Hedwall, Shaula J.; Wooldridge, Brian

2017-01-01

Assessment of a species' status is a key part of management decision making for endangered and threatened species under the U.S. Endangered Species Act. Predicting the future state of the species is an essential part of species status assessment, and projection models can play an important role in developing predictions. We built a stochastic simulation model that incorporated parametric and environmental uncertainty to predict the probable future status of the Sonoran desert tortoise in the southwestern United States and North Central Mexico. Sonoran desert tortoise was a Candidate species for listing under the Endangered Species Act, and decision makers wanted to use model predictions in their decision making process. The model accounted for future habitat loss and possible effects of climate change induced droughts to predict future population growth rates, abundances, and quasi-extinction probabilities. Our model predicts that the population will likely decline over the next few decades, but there is very low probability of quasi-extinction less than 75 years into the future. Increases in drought frequency and intensity may increase extinction risk for the species. Our model helped decision makers predict and characterize uncertainty about the future status of the species in their listing decision. We incorporated complex ecological processes (e.g., climate change effects on tortoises) in transparent and explicit ways tailored to support decision making processes related to endangered species.

Collective motion of predictive swarms

PubMed Central

Vural, Dervis Can

2017-01-01

Theoretical models of populations and swarms typically start with the assumption that the motion of agents is governed by the local stimuli. However, an intelligent agent, with some understanding of the laws that govern its habitat, can anticipate the future, and make predictions to gather resources more efficiently. Here we study a specific model of this kind, where agents aim to maximize their consumption of a diffusing resource, by attempting to predict the future of a resource field and the actions of other agents. Once the agents make a prediction, they are attracted to move towards regions that have, and will have, denser resources. We find that the further the agents attempt to see into the future, the more their attempts at prediction fail, and the less resources they consume. We also study the case where predictive agents compete against non-predictive agents and find the predictors perform better than the non-predictors only when their relative numbers are very small. We conclude that predictivity pays off either when the predictors do not see too far into the future or the number of predictors is small. PMID:29065136

Collective motion of predictive swarms.

PubMed

Rupprecht, Nathaniel; Vural, Dervis Can

2017-01-01

Theoretical models of populations and swarms typically start with the assumption that the motion of agents is governed by the local stimuli. However, an intelligent agent, with some understanding of the laws that govern its habitat, can anticipate the future, and make predictions to gather resources more efficiently. Here we study a specific model of this kind, where agents aim to maximize their consumption of a diffusing resource, by attempting to predict the future of a resource field and the actions of other agents. Once the agents make a prediction, they are attracted to move towards regions that have, and will have, denser resources. We find that the further the agents attempt to see into the future, the more their attempts at prediction fail, and the less resources they consume. We also study the case where predictive agents compete against non-predictive agents and find the predictors perform better than the non-predictors only when their relative numbers are very small. We conclude that predictivity pays off either when the predictors do not see too far into the future or the number of predictors is small.

Digital Telematics: Present and Future.

ERIC Educational Resources Information Center

Stalberg, Christian E.

1987-01-01

This overview of developments in international telecommunications networks focuses on their importance for developing countries and the necessary interdependence of all countries. Highlights include digital technology, telephone service, packet switching networks, communications satellites, fiber optic cables, and possible future developments.…

The future of laboratory medicine - a 2014 perspective.

PubMed

Kricka, Larry J; Polsky, Tracey G; Park, Jason Y; Fortina, Paolo

2015-01-01

Predicting the future is a difficult task. Not surprisingly, there are many examples and assumptions that have proved to be wrong. This review surveys the many predictions, beginning in 1887, about the future of laboratory medicine and its sub-specialties such as clinical chemistry and molecular pathology. It provides a commentary on the accuracy of the predictions and offers opinions on emerging technologies, economic factors and social developments that may play a role in shaping the future of laboratory medicine. Copyright © 2014 Elsevier B.V. All rights reserved.

Harnessing Light: Capitalizing on Optical Science Trends and Challenges for Future Research

DTIC Science & Technology

2012-12-31

Optics: The 96th OSA Annual Meeting and Exhibit ( FiO ) 10/14- 10/18 Rochester, New York http://www.frontiersinoptics.com/ Publication & Products...Virginiaq VINCENT J. RUSSO , Aerospace Technologies Associates, LLC, Dayton, Ohio KENNETH H. SANDHAGE, Georgia Institute of Technology, Atlanta, Georgia

Optical information processing for NASA's space exploration

NASA Technical Reports Server (NTRS)

Chao, Tien-Hsin; Ochoa, Ellen; Juday, Richard

1990-01-01

The development status of optical processing techniques under development at NASA-JPL, NASA-Ames, and NASA-Johnson, is evaluated with a view to their potential applications in future NASA planetary exploration missions. It is projected that such optical processing systems can yield major reductions in mass, volume, and power requirements relative to exclusively electronic systems of comparable processing capabilities. Attention is given to high-order neural networks for distortion-invariant classification and pattern recognition, multispectral imaging using an acoustooptic tunable filter, and an optical matrix processor for control problems.

Nonlinear optical oscillation dynamics in high-Q lithium niobate microresonators.

PubMed

Sun, Xuan; Liang, Hanxiao; Luo, Rui; Jiang, Wei C; Zhang, Xi-Cheng; Lin, Qiang

2017-06-12

Recent advance of lithium niobate microphotonic devices enables the exploration of intriguing nonlinear optical effects. We show complex nonlinear oscillation dynamics in high-Q lithium niobate microresonators that results from unique competition between the thermo-optic nonlinearity and the photorefractive effect, distinctive to other device systems and mechanisms ever reported. The observed phenomena are well described by our theory. This exploration helps understand the nonlinear optical behavior of high-Q lithium niobate microphotonic devices which would be crucial for future application of on-chip nonlinear lithium niobate photonics.

Accelerated optical polymer aging studies for LED luminaire applications

NASA Astrophysics Data System (ADS)

Estupiñán, Edgar; Wendling, Peter; Kostrun, Marijan; Garner, Richard

2013-09-01

There is a need in the lighting industry to design and implement accelerated aging methods that accurately simulate the aging process of LED luminaire components. In response to this need, we have built a flexible and reliable system to study the aging characteristics of optical polymer materials, and we have employed it to study a commercially available LED luminaire diffuser made of PMMA. The experimental system consists of a "Blue LED Emitter" and a working surface. Both the temperatures of the samples and the optical powers of the LEDs are appropriately characterized in the system. Several accelerated aging experiments are carried out at different temperatures and optical powers over a 90 hour period and the measured transmission values are used as inputs to a degradation model derived using plausibility arguments. This model seems capable of predicting the behavior of the material as a function of time, temperature and optical power. The model satisfactorily predicts the measured transmission values of diffusers aged in luminaires at two different times and thus can be used to make application recommendations for this material. Specifically, at 35000 hours (the manufacturer's stated life of the luminaire) and at the typical operational temperature of the diffuser, the model predicts a transmission loss of only a few percent over the original transmission of the material at 450 nm, which renders this material suitable for this application.

Solar Field Optical Characterization at Stillwater Geothermal/Solar Hybrid Plant

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

Zhu, Guangdong; Turchi, Craig

Concentrating solar power (CSP) can provide additional thermal energy to boost geothermal plant power generation. For a newly constructed solar field at a geothermal power plant site, it is critical to properly characterize its performance so that the prediction of thermal power generation can be derived to develop an optimum operating strategy for a hybrid system. In the past, laboratory characterization of a solar collector has often extended into the solar field performance model and has been used to predict the actual solar field performance, disregarding realistic impacting factors. In this work, an extensive measurement on mirror slope error andmore » receiver position error has been performed in the field by using the optical characterization tool called Distant Observer (DO). Combining a solar reflectance sampling procedure, a newly developed solar characterization program called FirstOPTIC and public software for annual performance modeling called System Advisor Model (SAM), a comprehensive solar field optical characterization has been conducted, thus allowing for an informed prediction of solar field annual performance. The paper illustrates this detailed solar field optical characterization procedure and demonstrates how the results help to quantify an appropriate tracking-correction strategy to improve solar field performance. In particular, it is found that an appropriate tracking-offset algorithm can improve the solar field performance by about 15%. The work here provides a valuable reference for the growing CSP industry.« less

Solar Field Optical Characterization at Stillwater Geothermal/Solar Hybrid Plant

DOE PAGES

Zhu, Guangdong; Turchi, Craig

2017-01-27

Concentrating solar power (CSP) can provide additional thermal energy to boost geothermal plant power generation. For a newly constructed solar field at a geothermal power plant site, it is critical to properly characterize its performance so that the prediction of thermal power generation can be derived to develop an optimum operating strategy for a hybrid system. In the past, laboratory characterization of a solar collector has often extended into the solar field performance model and has been used to predict the actual solar field performance, disregarding realistic impacting factors. In this work, an extensive measurement on mirror slope error andmore » receiver position error has been performed in the field by using the optical characterization tool called Distant Observer (DO). Combining a solar reflectance sampling procedure, a newly developed solar characterization program called FirstOPTIC and public software for annual performance modeling called System Advisor Model (SAM), a comprehensive solar field optical characterization has been conducted, thus allowing for an informed prediction of solar field annual performance. The paper illustrates this detailed solar field optical characterization procedure and demonstrates how the results help to quantify an appropriate tracking-correction strategy to improve solar field performance. In particular, it is found that an appropriate tracking-offset algorithm can improve the solar field performance by about 15%. The work here provides a valuable reference for the growing CSP industry.« less

Al nanogrid electrode for ultraviolet detectors.

PubMed

Ding, G; Deng, J; Zhou, L; Gan, Q; Hwang, J C M; Dierolf, V; Bartoli, F J; Mazuir, C; Schoenfeld, W V

2011-09-15

Optical properties of Al nanogrids of different pitches and gaps were investigated both theoretically and experimentally. Three-dimensional finite-difference time-domain simulation predicted that surface plasmons at the air/Al interface would enhance ultraviolet transmission through the subwavelength gaps of the nanogrid, making it an effective electrode on GaN-based photodetectors to compensate for the lack of transparent electrode and high p-type doping. The predicted transmission enhancement was verified by confocal scanning optical microscopy performed at 365 nm. The quality of the nanogrids fabricated by electron-beam lithography was verified by near-field scanning optical microscopy and scanning electron microscopy. Based on the results, the pitch and gap of the nanogrids can be optimized for the best trade-off between electrical conductivity and optical transmission at different wavelengths. Based on different cutoff wavelengths, the nanogrids can also double as a filter to render photodetectors solar-blind.

A comparison between GO/aperture-field and physical-optics methods for offset reflectors

NASA Technical Reports Server (NTRS)

Rahmat-Samii, Y.

1984-01-01

Both geometrical optics (GO)/aperture-field and physical-optics (PO) methods are used extensively in the diffraction analysis of offset parabolic and dual reflectors. An analytical/numerical comparative study is performed to demonstrate the limitations of the GO/aperture-field method for accurately predicting the sidelobe and null positions and levels. In particular, it is shown that for offset parabolic reflectors and for feeds located at the focal point, the predicted far-field patterns (amplitude) by the GO/aperture-field method will always be symmetric even in the offset plane. This, of course, is inaccurate for the general case and it is shown that the physical-optics method can result in asymmetric patterns for cases in which the feed is located at the focal point. Representative numerical data are presented and a comparison is made with available measured data.

Design of a fiber-optic multiphoton microscopy handheld probe

PubMed Central

Zhao, Yuan; Sheng, Mingyu; Huang, Lin; Tang, Shuo

2016-01-01

We have developed a fiber-optic multiphoton microscopy (MPM) system with handheld probe using femtosecond fiber laser. Here we present the detailed optical design and analysis of the handheld probe. The optical systems using Lightpath 352140 and 352150 as objective lens were analyzed. A custom objective module that includes Lightpath 355392 and two customized corrective lenses was designed. Their performances were compared by wavefront error, field curvature, astigmatism, F-θ error, and tolerance in Zemax simulation. Tolerance analysis predicted the focal spot size to be 1.13, 1.19 and 0.83 µm, respectively. Lightpath 352140 and 352150 were implemented in experiment and the measured lateral resolution was 1.22 and 1.3 µm, respectively, which matched with the prediction. MPM imaging by the handheld probe were conducted on leaf, fish scale and rat tail tendon. The MPM resolution can potentially be improved by the custom objective module. PMID:27699109

Design of a fiber-optic multiphoton microscopy handheld probe.

PubMed

Zhao, Yuan; Sheng, Mingyu; Huang, Lin; Tang, Shuo

2016-09-01

We have developed a fiber-optic multiphoton microscopy (MPM) system with handheld probe using femtosecond fiber laser. Here we present the detailed optical design and analysis of the handheld probe. The optical systems using Lightpath 352140 and 352150 as objective lens were analyzed. A custom objective module that includes Lightpath 355392 and two customized corrective lenses was designed. Their performances were compared by wavefront error, field curvature, astigmatism, F-θ error, and tolerance in Zemax simulation. Tolerance analysis predicted the focal spot size to be 1.13, 1.19 and 0.83 µm, respectively. Lightpath 352140 and 352150 were implemented in experiment and the measured lateral resolution was 1.22 and 1.3 µm, respectively, which matched with the prediction. MPM imaging by the handheld probe were conducted on leaf, fish scale and rat tail tendon. The MPM resolution can potentially be improved by the custom objective module.

Resonant indirect optical absorption in germanium

NASA Astrophysics Data System (ADS)

Menéndez, José; Noël, Mario; Zwinkels, Joanne C.; Lockwood, David J.

2017-09-01

The optical absorption coefficient of pure Ge has been determined from high-accuracy, high-precision optical measurements at photon energies covering the spectral range between the indirect and direct gaps. The results are compared with a theoretical model that fully accounts for the resonant nature of the energy denominators that appear in perturbation-theory expansions of the absorption coefficient. The model generalizes the classic Elliott approach to indirect excitons, and leads to a predicted optical absorption that is in excellent agreement with the experimental values using just a single adjustable parameter: the average deformation potential DΓ L coupling electrons at the bottom of the direct and indirect valleys in the conduction band. Remarkably, the fitted value, DΓ L=4.3 ×108eV /cm , is in nearly perfect agreement with independent measurements and ab initio predictions of this parameter, confirming the validity of the proposed theory, which has general applicability.

Role of impurities on the optical properties of rectangular graphene flakes

NASA Astrophysics Data System (ADS)

Sadeq, Z. S.; Muniz, Rodrigo A.; Sipe, J. E.

2018-01-01

We study rectangular graphene flakes using mean field states as the basis for a configuration interaction calculation, which allows us to analyze the low lying electronic excited states including electron correlations beyond the mean field level. We find that the lowest energy transition is polarized along the long axis of the flake, but the charge distributions involved in these transitions are invariably localized on the zigzag edges. We also investigate the impact of both short and long range impurity potentials on the optical properties of these systems. We predict that even a weak impurity localized at a zigzag edge of the flake can have a significant—and often dramatic—effect on its optical properties. This is in contrast to impurities localized at armchair edges or central regions of the flake, for which we predict almost no change to the optical properties of the flake even with strong impurity potentials.

Simple approach for high-contrast optical imaging and characterization of graphene-based sheets.

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

Jung, I.; Pelton, M.; Piner, R.

2007-12-01

A simple optical method is presented for identifying and measuring the effective optical properties of nanometer-thick, graphene-based materials, based on the use of substrates consisting of a thin dielectric layer on silicon. High contrast between the graphene-based materials and the substrate is obtained by choosing appropriate optical properties and thickness of the dielectric layer. The effective refractive index and optical absorption coefficient of graphene oxide, thermally reduced graphene oxide, and graphene are obtained by comparing the predicted and measured contrasts.

Using Emotion as Information in Future-Oriented Cognition: Individual Differences in the Context of State Negative Affect

PubMed Central

Marroquín, Brett; Boyle, Chloe C.; Nolen-Hoeksema, Susan; Stanton, Annette L.

2016-01-01

Predictions about the future are susceptible to mood-congruent influences of emotional state. However, recent work suggests individuals also differ in the degree to which they incorporate emotion into cognition. This study examined the role of such individual differences in the context of state negative emotion. We examined whether trait tendencies to use negative or positive emotion as information affect individuals' predictions of what will happen in the future (likelihood estimation) and how events will feel (affective forecasting), and whether trait influences depend on emotional state. Participants (N=119) reported on tendencies to use emotion as information (“following feelings”), underwent an emotion induction (negative versus neutral), and made likelihood estimates and affective forecasts for future events. Views of the future were predicted by both emotional state and individual differences in following feelings. Whereas following negative feelings affected most future-oriented cognition across emotional states, following positive feelings specifically buffered individuals' views of the future in the negative emotion condition, and specifically for positive future events, a category of future-event prediction especially important in psychological health. Individual differences may confer predisposition toward optimistic or pessimistic expectations of the future in the context of acute negative emotion, with implications for adaptive and maladaptive functioning. PMID:27041783

Longitudinally Jointed Edge-wise Compression Honeycomb Composite Sandwich Coupon Testing and FE Analysis: Three Methods of Strain Measurement, and Comparison

NASA Technical Reports Server (NTRS)

Farrokh, Babak; AbdulRahim, Nur Aida; Segal, Ken; Fan, Terry; Jones, Justin; Hodges, Ken; Mashni, Noah; Garg, Naman; Sang, Alex; Gifford, Dawn;