Optical fibres in the radiation environment of CERN

NASA Astrophysics Data System (ADS)

Guillermain, E.

2017-11-01

CERN, the European Organization for Nuclear Research (in Geneva, Switzerland), is home to a complex scientific instrument: the 27-kilometre Large Hadron Collider (LHC) collides beams of high-energy particles at close to the speed of light. Optical fibres are widely used at CERN, both in surface areas (e.g. for inter-building IT networks) and in the accelerator complex underground (e.g. for cryogenics, vacuum, safety systems). Optical fibres in the accelerator are exposed to mixed radiation fields (mainly composed of protons, pions, neutrons and other hadrons, gamma rays and electrons), with dose rates depending on the particular installation zone, and with radiation levels often significantly higher than those encountered in space. In the LHC and its injector chain radiation levels range from relatively low annual doses of a few Gy up to hundreds of kGy. Optical fibres suffer from Radiation Induced Attenuation (RIA, expressed in dB per unit length) that affect light transmission and which depends on the irradiation conditions (e.g. dose rate, total dose, temperature). In the CERN accelerator complex, the failure of an optical link can affect the proper functionality of control or monitoring systems and induce the interruption of the accelerator operation. The qualification of optical fibres for installation in critical radiation areas is therefore crucial. Thus, all optical fibre types installed in radiation areas at CERN are subject to laboratory irradiation tests, in order to evaluate their RIA at different total dose and dose rates. This allows the selection of the appropriate optical fibre type (conventional or radiation resistant) compliant with the requirements of each installation. Irradiation tests are performed in collaboration with Fraunhofer INT (irradiation facilities and expert team in Euskirchen, Germany). Conventional off-the-shelf optical fibres can be installed for optical links exposed to low radiation levels (i.e. annual dose typically below few kGy). Nevertheless, the conventional optical fibres must be carefully qualified as a spread in RIA of factor 10 is observed among optical fibres of different types and dopants. In higher radiation areas, special radiation resistant optical fibres are installed. For total dose above 1 kGy, the RIA of these special optical fibres is at least 10 times lower than the conventional optical fibres RIA at same irradiation conditions. 2400 km of these special radiation resistant optical fibres were recently procured at CERN. As part of this procurement process, a quality assurance plan including the irradiation testing of all 65 produced batches was set up. This presentation will review the selection process of the appropriate optical fibre types to be installed in the radiation environment of CERN. The methodology for choosing the irradiation parameters for the laboratory tests will be discussed together with an overview of the RIA of different optical fibre types under several irradiation conditions.

Optical+NIR Quasar Selection with the SDSS and UKIDSS

NASA Astrophysics Data System (ADS)

Mehta, Sajjan S.; Mahon, R. G.; Richards, G. T.; Hewett, P. C.

2010-01-01

We present the details of an optical+near-IR quasar selection technique, which utilizes near-IR data from the UKIDSS Large Area Survey and the optical data from the Sloan Digital Sky Survey in the SDSS's deep "Stripe 82" region, which covers over 200 deg2. Our selection methods primarily consist of isolating potential candidates in giK and gJK color space, in which there exists a significant separation of the stellar locus from the quasar locus. Additionally, we discuss secondary techniques such as comparison of catalog magnitudes with aperture photometry, analysis of SDSS and UKIDSS morphological type classifications, and flag cuts. Our primary color-cut selections include most quasars with redshifts below 3.4, significantly increasing the completeness both to dust reddened quasars and quasars with redshifts z 2.7 in the SDSS footprint. A simple color cut in the UKIDSS LAS Stripe 82 regions reveals 4200 quasar candidates down to K=18. These NIR selections have been used to contribute to the Baryon Oscillation Spectroscopic Survey (BOSS), which is one of the four surveys of the SDSS-III collaboration. We additionally intend to use our NIR techniques to perform an 8-dimensional optical+NIR Bayesian selection of quasars for the AAOmege UKIDSS SDSS (AUS) survey.

Collisional Lifetimes of Elementary Excitations in Two-Dimensional Systems in the Field of a Strong Electromagnetic Wave

NASA Astrophysics Data System (ADS)

Kovalev, V. M.

2018-04-01

A two-dimensional system with two nonequivalent valleys in the field of a strong circularly polarized electromagnetic wave is considered. It is assumed that the optical selection rules for a given polarization of light allow band-to-band transitions only in valleys of one, optically active, type (two-dimensional layer based on transition metal dichalcogenides, gapped graphene, etc.). This leads to the formation of photon-coupled electron-hole pairs, or an "optical insulator" state. It is assumed that the valleys of the second type (optically inactive) are populated with an equilibrium electron gas. The relaxation of elementary excitations in this hybrid system consisting of an electron gas and a gas of electron-hole pairs caused by the Coulomb interaction between the particles is investigated.

Photoinduced Electron Transfer Based Ion Sensing within an Optical Fiber

PubMed Central

Englich, Florian V.; Foo, Tze Cheung; Richardson, Andrew C.; Ebendorff-Heidepriem, Heike; Sumby, Christopher J.; Monro, Tanya M.

2011-01-01

We combine suspended-core microstructured optical fibers with the photoinduced electron transfer (PET) effect to demonstrate a new type of fluorescent optical fiber-dip sensing platform for small volume ion detection. A sensor design based on a simple model PET-fluoroionophore system and small core microstructured optical fiber capable of detecting sodium ions is demonstrated. The performance of the dip sensor operating in a high sodium concentration regime (925 ppm Na+) and for lower sodium concentration environments (18.4 ppm Na+) is explored and future approaches to improving the sensor’s signal stability, sensitivity and selectivity are discussed. PMID:22163712

Optimal Filter Estimation for Lucas-Kanade Optical Flow

PubMed Central

Sharmin, Nusrat; Brad, Remus

2012-01-01

Optical flow algorithms offer a way to estimate motion from a sequence of images. The computation of optical flow plays a key-role in several computer vision applications, including motion detection and segmentation, frame interpolation, three-dimensional scene reconstruction, robot navigation and video compression. In the case of gradient based optical flow implementation, the pre-filtering step plays a vital role, not only for accurate computation of optical flow, but also for the improvement of performance. Generally, in optical flow computation, filtering is used at the initial level on original input images and afterwards, the images are resized. In this paper, we propose an image filtering approach as a pre-processing step for the Lucas-Kanade pyramidal optical flow algorithm. Based on a study of different types of filtering methods and applied on the Iterative Refined Lucas-Kanade, we have concluded on the best filtering practice. As the Gaussian smoothing filter was selected, an empirical approach for the Gaussian variance estimation was introduced. Tested on the Middlebury image sequences, a correlation between the image intensity value and the standard deviation value of the Gaussian function was established. Finally, we have found that our selection method offers a better performance for the Lucas-Kanade optical flow algorithm.

Dissolved organic carbon and unimodal variation in sexual signal coloration in mosquitofish: a role for light limitation?

PubMed Central

Layman, Craig A.

2017-01-01

Natural selection plays an important role in the evolution of sexual communication systems. Here, we assess the effect of two well-known selection agents, transmission environment and predation, on interpopulation variation in sexual signals. Our model system is a series of 21 populations of Bahamian mosquitofish subjected to independent variation in optical conditions and predation risk. We show that optically diverse environments, caused by locally variable dissolved organic carbon concentrations, rather than spatial variation in predation, drove divergence in fin coloration (fin redness). We found a unimodal pattern of phenotypic variation along the optical gradient indicating a threshold-type response of visual signals to broad variation in optical conditions. We discuss evolutionary and ecological mechanisms that may drive such a pattern as well as the implications of non-monotonic clines for evolutionary differentiation. PMID:28381625

Dissolved organic carbon and unimodal variation in sexual signal coloration in mosquitofish: a role for light limitation?

PubMed

Giery, Sean T; Layman, Craig A

2017-04-12

Natural selection plays an important role in the evolution of sexual communication systems. Here, we assess the effect of two well-known selection agents, transmission environment and predation, on interpopulation variation in sexual signals. Our model system is a series of 21 populations of Bahamian mosquitofish subjected to independent variation in optical conditions and predation risk. We show that optically diverse environments, caused by locally variable dissolved organic carbon concentrations, rather than spatial variation in predation, drove divergence in fin coloration (fin redness). We found a unimodal pattern of phenotypic variation along the optical gradient indicating a threshold-type response of visual signals to broad variation in optical conditions. We discuss evolutionary and ecological mechanisms that may drive such a pattern as well as the implications of non-monotonic clines for evolutionary differentiation. © 2017 The Author(s).

High resolution earth observation from geostationary orbit by optical aperture synthesys

NASA Astrophysics Data System (ADS)

Mesrine, M.; Thomas, E.; Garin, S.; Blanc, P.; Alis, C.; Cassaing, F.; Laubier, D.

2017-11-01

In this paper, we describe Optical Aperture Synthesis (OAS) imaging instrument concepts studied by Alcatel Alenia Space under a CNES R&T contract in term of technical feasibility. First, the methodology to select the aperture configuration is proposed, based on the definition and quantification of image quality criteria adapted to an OAS instrument for direct imaging of extended objects. The following section presents, for each interferometer type (Michelson and Fizeau), the corresponding optical configurations compatible with a large field of view from GEO orbit. These optical concepts take into account the constraints imposed by the foreseen resolution and the implementation of the co-phasing functions. The fourth section is dedicated to the analysis of the co-phasing methodologies, from the configuration deployment to the fine stabilization during observation. Finally, we present a trade-off analysis allowing to select the concept wrt mission specification and constraints related to instrument accommodation under launcher shroud and in-orbit deployment.

Optical biosensors.

PubMed

Damborský, Pavel; Švitel, Juraj; Katrlík, Jaroslav

2016-06-30

Optical biosensors represent the most common type of biosensor. Here we provide a brief classification, a description of underlying principles of operation and their bioanalytical applications. The main focus is placed on the most widely used optical biosensors which are surface plasmon resonance (SPR)-based biosensors including SPR imaging and localized SPR. In addition, other optical biosensor systems are described, such as evanescent wave fluorescence and bioluminescent optical fibre biosensors, as well as interferometric, ellipsometric and reflectometric interference spectroscopy and surface-enhanced Raman scattering biosensors. The optical biosensors discussed here allow the sensitive and selective detection of a wide range of analytes including viruses, toxins, drugs, antibodies, tumour biomarkers and tumour cells. © 2016 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

Fibre Optic Sensors for Selected Wastewater Characteristics

PubMed Central

Chong, Su Sin; Abdul Aziz, A. R.; Harun, Sulaiman W.

2013-01-01

Demand for online and real-time measurements techniques to meet environmental regulation and treatment compliance are increasing. However the conventional techniques, which involve scheduled sampling and chemical analysis can be expensive and time consuming. Therefore cheaper and faster alternatives to monitor wastewater characteristics are required as alternatives to conventional methods. This paper reviews existing conventional techniques and optical and fibre optic sensors to determine selected wastewater characteristics which are colour, Chemical Oxygen Demand (COD) and Biological Oxygen Demand (BOD). The review confirms that with appropriate configuration, calibration and fibre features the parameters can be determined with accuracy comparable to conventional method. With more research in this area, the potential for using FOS for online and real-time measurement of more wastewater parameters for various types of industrial effluent are promising. PMID:23881131

Enhanced and selective optical trapping in a slot-graphite photonic crystal.

PubMed

Krishnan, Aravind; Huang, Ningfeng; Wu, Shao-Hua; Martínez, Luis Javier; Povinelli, Michelle L

2016-10-03

Applicability of optical trapping tools for nanomanipulation is limited by the available laser power and trap efficiency. We utilized the strong confinement of light in a slot-graphite photonic crystal to develop high-efficiency parallel trapping over a large area. The stiffness is 35 times higher than our previously demonstrated on-chip, near field traps. We demonstrate the ability to trap both dielectric and metallic particles of sub-micron size. We find that the growth kinetics of nanoparticle arrays on the slot-graphite template depends on particle size. This difference is exploited to selectively trap one type of particle out of a binary colloidal mixture, creating an efficient optical sieve. This technique has rich potential for analysis, diagnostics, and enrichment and sorting of microscopic entities.

Infrared vibrational nanocrystallography and nanoimaging

PubMed Central

Muller, Eric A.; Pollard, Benjamin; Bechtel, Hans A.; van Blerkom, Peter; Raschke, Markus B.

2016-01-01

Molecular solids and polymers can form low-symmetry crystal structures that exhibit anisotropic electron and ion mobility in engineered devices or biological systems. The distribution of molecular orientation and disorder then controls the macroscopic material response, yet it is difficult to image with conventional techniques on the nanoscale. We demonstrated a new form of optical nanocrystallography that combines scattering-type scanning near-field optical microscopy with both optical antenna and tip-selective infrared vibrational spectroscopy. From the symmetry-selective probing of molecular bond orientation with nanometer spatial resolution, we determined crystalline phases and orientation in aggregates and films of the organic electronic material perylenetetracarboxylic dianhydride. Mapping disorder within and between individual nanoscale domains, the correlative hybrid imaging of nanoscale heterogeneity provides insight into defect formation and propagation during growth in functional molecular solids. PMID:27730212

Design Reference Missions for Deep-Space Optical Communication

NASA Astrophysics Data System (ADS)

Breidenthal, J.; Abraham, D.

2016-05-01

We examined the potential, but uncertain, NASA mission portfolio out to a time horizon of 20 years, to identify mission concepts that potentially could benefit from optical communication, considering their communications needs, the environments in which they would operate, and their notional size, weight, and power constraints. A set of 12 design reference missions was selected to represent the full range of potential missions. These design reference missions span the space of potential customer requirements, and encompass the wide range of applications that an optical ground segment might eventually be called upon to serve. The design reference missions encompass a range of orbit types, terminal sizes, and positions in the solar system that reveal the chief system performance variables of an optical ground segment, and may be used to enable assessments of the ability of alternative systems to meet various types of customer needs.

Designing and specifying aspheres for manufacturability

NASA Astrophysics Data System (ADS)

Kumler, Jay

2005-08-01

New technologies for the fabrication of aspheres have increased opportunities for using aspheres in a wider range of optical systems. If manufacturability is considered early in the optical design process, the short and long term costs of the aspheric surface can be greatly reduced without sacrificing performance. The optical designer must learn how to select optimum materials for aspheres. Using non-staining glasses, higher index glass types, and softer glass types can help reduce production costs. If the optical designer understands what range of aspheric surfaces can be manufactured, they can constrain the aspheric surface during optimization. The steepness of the aspheric departure (the slope of the aspheric departure) often has a larger impact on manufacturing difficulty than the amplitude of the asphere or the steepness of the base radius. Tolerancing can increase the difficulty without measurably improving optical performance. Finally, the asphere can be designed for ease of metrology. Understanding the options that are available for aspheric metrology will allow the engineer to control tooling and fixturing that is required for testing.

Model for a pulsed terahertz quantum cascade laser under optical feedback.

PubMed

Agnew, Gary; Grier, Andrew; Taimre, Thomas; Lim, Yah Leng; Bertling, Karl; Ikonić, Zoran; Valavanis, Alexander; Dean, Paul; Cooper, Jonathan; Khanna, Suraj P; Lachab, Mohammad; Linfield, Edmund H; Davies, A Giles; Harrison, Paul; Indjin, Dragan; Rakić, Aleksandar D

2016-09-05

Optical feedback effects in lasers may be useful or problematic, depending on the type of application. When semiconductor lasers are operated using pulsed-mode excitation, their behavior under optical feedback depends on the electronic and thermal characteristics of the laser, as well as the nature of the external cavity. Predicting the behavior of a laser under both optical feedback and pulsed operation therefore requires a detailed model that includes laser-specific thermal and electronic characteristics. In this paper we introduce such a model for an exemplar bound-to-continuum terahertz frequency quantum cascade laser (QCL), illustrating its use in a selection of pulsed operation scenarios. Our results demonstrate significant interplay between electro-optical, thermal, and feedback phenomena, and that this interplay is key to understanding QCL behavior in pulsed applications. Further, our results suggest that for many types of QCL in interferometric applications, thermal modulation via low duty cycle pulsed operation would be an alternative to commonly used adiabatic modulation.

Optical/Near-infrared Selection of Red Quasi-stellar Objects: Evidence for Steep Extinction Curves toward Galactic Centers?

NASA Astrophysics Data System (ADS)

Fynbo, J. P. U.; Krogager, J.-K.; Venemans, B.; Noterdaeme, P.; Vestergaard, M.; Møller, P.; Ledoux, C.; Geier, S.

2013-01-01

We present the results of a search for red QSOs using a selection based on optical imaging from the Sloan Digital Sky Survey (SDSS) and near-infrared imaging from UKIDSS. Our main goal with the selection is to search for QSOs reddened by foreground dusty absorber galaxies. For a sample of 58 candidates (including 20 objects fulfilling our selection criteria that already have spectra in the SDSS), 46 (79%) are confirmed to be QSOs. The QSOs are predominantly dust-reddened except for a handful at redshifts z >~ 3.5. However, the dust is most likely located in the QSO host galaxies (and for two, the reddening is primarily caused by Galactic dust) rather than in the intervening absorbers. More than half of the QSOs show evidence of associated absorption (BAL absorption). Four (7%) of the candidates turned out to be late-type stars, and another four (7%) are compact galaxies. We could not identify the remaining four objects. In terms of their optical spectra, these QSOs are similar to the QSOs selected in the FIRST-2MASS Red Quasar Survey except they are on average fainter, more distant, and only two are detected in the FIRST survey. As per the usual procedure, we estimate the amount of extinction using the SDSS QSO template reddened by Small-Magellanic-Cloud-(SMC) like dust. It is possible to get a good match to the observed (rest-frame ultraviolet) spectra, but it is not possible to match the observed near-IR photometry from UKIDSS for nearly all the reddened QSOs. The most likely reasons are that the SDSS QSO template is too red at optical wavelengths due to contaminating host galaxy light and because the assumed SMC extinction curve is too shallow. Three of the compact galaxies display old stellar populations with ages of several Gyr and masses of about 1010 M ⊙ (based on spectral energy distribution modeling). The inferred stellar densities in these galaxies exceed 1010 M ⊙ kpc-2, which is among the highest measured for early-type galaxies. Our survey has demonstrated that selection of QSOs based on near-IR photometry is an efficient way to select QSOs, including reddened QSOs, with only small contamination from late-type stars and compact galaxies. This will be useful with ongoing and future wide-field near-IR surveys such as the VISTA and EUCLID surveys. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, under program 088.A-0098, and on observations made with the Nordic Optical Telescope, jointly operated on the island of La Palma by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.

Properties of an H I-selected galaxy sample

NASA Technical Reports Server (NTRS)

Szomoru, Arpad; Guhathakurta, Puragra; Van Gorkom, Jacqueline H.; Knapen, Johan H.; Weinberg, David H.; Fruchter, Andrew S.

1994-01-01

We analyze the properties of a sample of galaxies identified in a 21cm, H I-line survey of selected areas in the Perseus-Pisces supercluster and its foreground void. Twelve fields were observed in the supercluster, five of them (target fields) centered on optically bright galaxies, and the other seven (blank fields) selected to contain no bright galaxies within 45 min. of their centers. We detected nine previously uncatalogued, gas-rich galaxies, six of them in the target fields. We also detected H I from seven previously catalogued galaxies in these fields. Observations in the void covered the same volume as the 12 supercluster fields at the same H I-mass sensitivity, but no objects were detected. Combining out H I data with optical broadband and H alpha imaging, we conclude that the properties of H I-selected galaxies do not differ substantially from those of late-type galaxies found in optical surveys. In particular, the galaxies in our sample do not appear to be unusually faint for their H I mass, or for their circular velocity. We find tentative evidence for a connection between optical surface brightness and degree of isolation, in the sense that low surface brightness galaxies tend to be more isolated. The previously catalogued, optically bright galaxies in our survey volume dominate the total H I mass density and cross section; the uncatalogued galaxies contribute only approximately 19 percent of the mass and approximately 12 percent of the cross section. Thus, existing estimates of the density and cross section of neutral hydrogen, most of which are based on optically selected galaxy samples, are probably accurate. Such estimates can be used to compare the nearby universe to the high-redshift universe probed by quasar absorption lines.

Integration of multi-interface conversion channel using FPGA for modular photonic network

NASA Astrophysics Data System (ADS)

Janicki, Tomasz; Pozniak, Krzysztof T.; Romaniuk, Ryszard S.

2010-09-01

The article discusses the integration of different types of interfaces with FPGA circuits using a reconfigurable communication platform. The solution has been implemented in practice in a single node of a distributed measurement system. Construction of communication platform has been presented with its selected hardware modules, described in VHDL and implemented in FPGA circuits. The graphical user interface (GUI) has been described that allows a user to control the operation of the system. In the final part of the article selected practical solutions have been introduced. The whole measurement system resides on multi-gigabit optical network. The optical network construction is highly modular, reconfigurable and scalable.

Spin-lattice relaxation of optically polarized nuclei in p -type GaAs

NASA Astrophysics Data System (ADS)

Kotur, M.; Dzhioev, R. I.; Vladimirova, M.; Cherbunin, R. V.; Sokolov, P. S.; Yakovlev, D. R.; Bayer, M.; Suter, D.; Kavokin, K. V.

2018-04-01

Spin-lattice relaxation of the nuclear spin system in p -type GaAs is studied using a three-stage experimental protocol including optical pumping and measuring the difference of the nuclear spin polarization before and after a dark interval of variable length. This method allows us to measure the spin-lattice relaxation time T1 of optically pumped nuclei "in the dark," that is, in the absence of illumination. The measured T1 values fall into the subsecond time range, being three orders of magnitude shorter than in earlier studied n -type GaAs. The drastic difference is further emphasized by magnetic-field and temperature dependencies of T1 in p -GaAs, showing no similarity to those in n -GaAs. This unexpected behavior finds its explanation in the spatial selectivity of the optical pumping in p -GaAs, that is only efficient in the vicinity of shallow donors, together with the quadrupole relaxation of nuclear spins, which is induced by electric fields within closely spaced donor-acceptor pairs. The developed theoretical model explains the whole set of experimental results.

Initial Performance Evaluation of Optical Fibers and Sensors Under High-Energy Electron Beam Irradiation

NASA Astrophysics Data System (ADS)

Palmer, Matthew E.; Slusher, David; Fielder, Robert S.

2006-01-01

In this paper, recent work on the performance of optical fiber, fiber optic sensors, and fiber optic connectors under the influence of a high-energy electron beam is presented. Electron beam irradiation is relevant for the Jupiter Icy Moons Orbiter (JIMO) mission due to the high electron radiation environment surrounding Jupiter. As an initial feasibility test, selected optical fiber components were exposed to dose levels relevant to the Jupiter environment. Three separate fiber types were used: one series consisted of pure silica core fiber, two other series consisted of different levels of Germania-doped fiber. Additionally, a series of fused silica Extrinsic Fabry-Perot Interferometer (EFPI)-based fiber optic sensors and two different types of fiber optic connectors were tested. Two types of fiber coatings were evaluated: acrylate and polyimide. All samples were exposed to three different dose levels: 2 MRad, 20 MRad, and 50 MRad. Optical loss measurements were made on the optical fiber spools as a function of wavelength between 750 and 1750nm at periodic intervals up to 75 hrs after exposure. Attenuation is minimal and wavelength-dependent. Fiber optic sensors were evaluated using a standard EFPI sensor readout and diagnostic system. Optical connectors and optical fiber coatings were visually inspected for degradation. Additionally, tensile testing and minimum bend radius testing was conducted on the fibers. Initial loss measurements indicate a low-level of induced optical attenuation in the fiber which recovers with time. The fiber optic sensors exhibited no observable degradation after exposure. The optical fiber connectors and coatings also showed no observable degradation. In addition to harsh environment survivability, fiber optic sensors offer a number of intrinsic advantages for space nuclear power applications including extremely low mass, immunity to electromagnetic interference, self diagnostics / prognostics, and smart sensor capability. Deploying fiber optic sensors on future space exploration missions would provide a substantial improvement in spacecraft instrumentation.

A novel, highly sensitive, selective, reversible and turn-on chemi-sensor based on Schiff base for rapid detection of Cu(II)

NASA Astrophysics Data System (ADS)

Saleh, Sayed M.; Ali, Reham; Ali, Ibrahim A. I.

2017-08-01

In this work, a novel optical fluoro-chemisensor was designed and synthesized for copper (II) ions detection. The sensor film is created by embedded N,N-Bis(2-hydroxo-5-bromobenzyl)ethylenediamine in poly vinyl chloride (PVC) film in presence of dioctyl phthalate (DOP) as plasticizer. The receptor Schiff base reveals "off-on" mode with high selectivity, significant sensitivity to Cu(II) ions. The selectivity of optical sensor for Cu(II) ions is the result of chelation enhanced fluorescence (CHEF). The optimal conditions of pH and response time at which higher efficiency of sensor film is performed was found to be 6.8 and 2.48 min. The possible interference of other metal ions in solution was examined in presence of different types of metal ions. This film shows high selectivity and ultra-sensitivity with low detection limit LOD (1.1 × 10- 8 M). Thus, these considerable properties make it viable to monitor copper metal ions within very low concentration range (0-15 × 10- 6 M Cu(II)) and highly selective even in the presence of different types of metal ions. The sensor reversibility was achieved by utilizing EDTA solution with concentration of 0.1 M solution.

Influence of laser beam profiles on received power fluctuation

NASA Astrophysics Data System (ADS)

Dordova, Lucie; Diblik, Jan

2011-09-01

Gaussian beam is very often used for the transmission of information in optical wireless links. The usage of this optical beam has its advantages and, of course, disadvantages. This work focuses on possibilities of using laser beams with different distribution of optical intensity - Top Hat beam. Creation of the optical beam with selected optical intensity profile will be briefly described. Optical beams will propagate through the "clear" and stationary atmosphere in the experimental part of this work. These results will be compared with the data obtained after a laser beam is passed through the turbulent and attenuated atmosphere. We will use an ultrasound fog generator for laser beam attenuation testing. To create the turbulence, infra radiators will be applied. Particular results obtained from different atmospheric conditions will be compared and using different types of optical beams will be assessed.

Differential Deposition for Surface Figure Corrections in Grazing Incidence X-Ray Optics

NASA Technical Reports Server (NTRS)

Ramsey, Brian D.; Kilaru, Kiranmayee; Atkins, Carolyn; Gubarev, Mikhail V.; Broadway, David M.

2015-01-01

Differential deposition corrects the low- and mid- spatial-frequency deviations in the axial figure of Wolter-type grazing incidence X-ray optics. Figure deviations is one of the major contributors to the achievable angular resolution. Minimizing figure errors can significantly improve the imaging quality of X-ray optics. Material of varying thickness is selectively deposited, using DC magnetron sputtering, along the length of optic to minimize figure deviations. Custom vacuum chambers are built that can incorporate full-shell and segmented Xray optics. Metrology data of preliminary corrections on a single meridian of full-shell x-ray optics show an improvement of mid-spatial frequencies from 6.7 to 1.8 arc secs HPD. Efforts are in progress to correct a full-shell and segmented optics and to verify angular-resolution improvement with X-ray testing.

The selection criteria elements of X-ray optics system

NASA Astrophysics Data System (ADS)

Plotnikova, I. V.; Chicherina, N. V.; Bays, S. S.; Bildanov, R. G.; Stary, O.

2018-01-01

At the design of new modifications of x-ray tomography there are difficulties in the right choice of elements of X-ray optical system. Now this problem is solved by practical consideration, selection of values of the corresponding parameters - tension on an x-ray tube taking into account the thickness and type of the studied material. For reduction of time and labor input of design it is necessary to create the criteria of the choice, to determine key parameters and characteristics of elements. In the article two main elements of X-ray optical system - an x-ray tube and the detector of x-ray radiation - are considered. Criteria of the choice of elements, their key characteristics, the main dependences of parameters, quality indicators and also recommendations according to the choice of elements of x-ray systems are received.

Transrectal Near-Infrared Optical Tomography for Prostate Imaging

DTIC Science & Technology

2010-03-01

valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) 31-03-2010 2. REPORT TYPE Annual 3...technology of trans-rectal near-infrared (NIR) optical tomography for accurate, selective prostate biopsy. Prostate cancer is the most common non ...mice and recovered/homogenized for injection into the non -immune suppressed dog’s prostate gland. Under general anesthesia, ~2 cc of TVT cells

Driver-receiver combined optical transceiver modules for bidirectional optical interconnection

NASA Astrophysics Data System (ADS)

Park, Hyo-Hoon; Kang, Sae-Kyoung; Kim, Do-Won; Nga, Nguyen T. H.; Hwang, Sung-Hwan; Lee, Tae-Woo

2008-02-01

We review a bidirectional optical link scheme for memory-interface applications. A driver-receiver combined optical transceiver (TRx) modules was demonstrated on an optical printed-circuit board (OPCB) platform. To select the bidirectional electric input/output signals, a driver-receiver combined TRx IC with a switching function was designed in 0.18-μm CMOS technology. The TRx IC was integrated with VCSEL/PD chips for optical link in the TRx module. The optical TRx module was assembled on a fiber-embedded OPCB, employing a 90°-bent fiber connector for 90° deflection of light beams between the TRx module and the OPCB. The TRx module and the 90° connector were passively assembled on the OPCB, using ferrule-type guide pins/ holes. Employing these constituent components, the bidirectional optical link between a pair of TRx modules has been successfully demonstrated up to 1.25 Gb/s on the OPCB.

MSM optical detector on the basis of II-type ZnSe/ZnTe superlattice

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

Kuznetzov, P. I., E-mail: pik218@ire216.msk.su; Averin, S. V., E-mail: sva278@ire216.msk.su; Zhitov, V. A.

2017-02-15

On the basis of a type-II ZnSe/ZnTe superlattice, a MSM (metal—semiconductor–metal) photodetector is fabricated and investigated. The detector features low dark currents and a high sensitivity. The spectral characteristic of the detector provides the possibility of the selective detection of three separate spectral portions of visible and near-infrared radiation.

Optical techniques for the determination of nitrate in environmental waters: Guidelines for instrument selection, operation, deployment, maintenance, quality assurance, and data reporting

USGS Publications Warehouse

Pellerin, Brian A.; Bergamaschi, Brian A.; Downing, Bryan D.; Saraceno, John Franco; Garrett, Jessica D.; Olsen, Lisa D.

2013-01-01

The recent commercial availability of in situ optical sensors, together with new techniques for data collection and analysis, provides the opportunity to monitor a wide range of water-quality constituents on time scales in which environmental conditions actually change. Of particular interest is the application of ultraviolet (UV) photometers for in situ determination of nitrate concentrations in rivers and streams. The variety of UV nitrate sensors currently available differ in several important ways related to instrument design that affect the accuracy of their nitrate concentration measurements in different types of natural waters. This report provides information about selection and use of UV nitrate sensors by the U.S. Geological Survey to facilitate the collection of high-quality data across studies, sites, and instrument types. For those in need of technical background and information about sensor selection, this report addresses the operating principles, key features and sensor design, sensor characterization techniques and typical interferences, and approaches for sensor deployment. For those needing information about maintaining sensor performance in the field, key sections in this report address maintenance and calibration protocols, quality-assurance techniques, and data formats and reporting. Although the focus of this report is UV nitrate sensors, many of the principles can be applied to other in situ optical sensors for water-quality studies.

Limits of colour vision in dim light.

PubMed

Kelber, Almut; Lind, Olle

2010-09-01

Humans and most vertebrates have duplex retinae with multiple cone types for colour vision in bright light, and one single rod type for achromatic vision in dim light. Instead of comparing signals from multiple spectral types of photoreceptors, such species use one highly sensitive receptor type thus improving the signal-to-noise ratio at night. However, the nocturnal hawkmoth Deilephila elpenor, the nocturnal bee Xylocopa tranquebarica and the nocturnal gecko Tarentola chazaliae can discriminate colours at extremely dim light intensities. To be able to do so, they sacrifice spatial and temporal resolution in favour of colour vision. We review what is known about colour vision in dim light, and compare colour vision thresholds with the optical sensitivity of the photoreceptors in selected animal species with lens and compound eyes. © 2010 The Authors, Ophthalmic and Physiological Optics © 2010 The College of Optometrists.

Comparison between Different Types of Sensors Used in the Real Operational Environment Based on Optical Scanning System.

PubMed

Flores-Fuentes, Wendy; Miranda-Vega, Jesús Elías; Rivas-López, Moisés; Sergiyenko, Oleg; Rodríguez-Quiñonez, Julio C; Lindner, Lars

2018-05-24

The present paper describes the experimentation in a controlled environment and a real environment using different photosensors, such as infrared light emitting diode (IRLED-as receiver), photodiode, light dependent resistor (LDR), and blue LED for the purpose of selecting those devices, which can be employed in adverse conditions, such as sunlight or artificial sources. The experiments that are described in this paper confirmed that the blue LED and phototransistor could be used as a photosensor of an Optical Scanning System (OSS), because they were less sensitive to sunlight radiation. Moreover, they are appropriate as reference sources that are selected for the experiment (blue LED flashlight and light bulb). The best experimental results that were obtained contained a digital filter that was applied to the output of the photosensor, which reduced the standard deviation for the best case for the phototransistor LED from 100.26 to 0.15. For the best case, using the blue LED, the standard deviation was reduced from 86.08 to 0.11. Using these types of devices the cost of the Optical Scanning System can be reduced and a considerable increase in resolution and accuracy.

Preferred mirror coatings for UV, visible, and IR space optical instruments

NASA Astrophysics Data System (ADS)

Heaney, James B.; Kauder, Lonny R.; Freese, Scott C.; Quijada, Manuel A.

2012-09-01

This paper will review the suitability of the common four types of reflecting surfaces - Ag, Al, Au and Be - for use aboard satellite borne remote sensing and astrophysical observatories, from the uv to far-ir spectral bands. The choice of appropriate protecting and reflectance enhancing overcoats for these reflecting metals will be discussed. Laboratory test data and optical diagnostic techniques used to verify durability of the selected coatings in a terrestrial storage environment and their sensitivity to a space radiation and cold temperature environment will be presented. For some of the selected coatings, a connection will be made between pre-launch laboratory quality checks and post-launch performance on orbit.

The X-CLASS-redMaPPer galaxy cluster comparison. I. Identification procedures

NASA Astrophysics Data System (ADS)

Sadibekova, T.; Pierre, M.; Clerc, N.; Faccioli, L.; Gastaud, R.; Le Fevre, J.-P.; Rozo, E.; Rykoff, E.

2014-11-01

Context. This paper is the first in a series undertaking a comprehensive correlation analysis between optically selected and X-ray-selected cluster catalogues. The rationale of the project is to develop a holistic picture of galaxy clusters utilising optical and X-ray-cluster-selected catalogues with well-understood selection functions. Aims: Unlike most of the X-ray/optical cluster correlations to date, the present paper focuses on the non-matching objects in either waveband. We investigate how the differences observed between the optical and X-ray catalogues may stem from (1) a shortcoming of the detection algorithms; (2) dispersion in the X-ray/optical scaling relations; or (3) substantial intrinsic differences between the cluster populations probed in the X-ray and optical bands. The aim is to inventory and elucidate these effects in order to account for selection biases in the further determination of X-ray/optical cluster scaling relations. Methods: We correlated the X-CLASS serendipitous cluster catalogue extracted from the XMM archive with the redMaPPer optical cluster catalogue derived from the Sloan Digital Sky Survey (DR8). We performed a detailed and, in large part, interactive analysis of the matching output from the correlation. The overlap between the two catalogues has been accurately determined and possible cluster positional errors were manually recovered. The final samples comprise 270 and 355 redMaPPer and X-CLASS clusters, respectively. X-ray cluster matching rates were analysed as a function of optical richness. In the second step, the redMaPPer clusters were correlated with the entire X-ray catalogue, containing point and uncharacterised sources (down to a few 10-15 erg s-1 cm-2 in the [0.5-2] keV band). A stacking analysis was performed for the remaining undetected optical clusters. Results: We find that all rich (λ ≥ 80) clusters are detected in X-rays out to z = 0.6. Below this redshift, the richness threshold for X-ray detection steadily decreases with redshift. Likewise, all X-ray bright clusters are detected by redMaPPer. After correcting for obvious pipeline shortcomings (about 10% of the cases both in optical and X-ray), ~50% of the redMaPPer (down to a richness of 20) are found to coincide with an X-CLASS cluster; when considering X-ray sources of any type, this fraction increases to ~80%; for the remaining objects, the stacking analysis finds a weak signal within 0.5 Mpc around the cluster optical centres. The fraction of clusters totally dominated by AGN-type emission appears to be a few percent. Conversely, ~40% of the X-CLASS clusters are identified with a redMaPPer (down to a richness of 20) - part of the non-matches being due to the X-CLASS sample extending further out than redMaPPer (z< 1.5 vs. z< 0.6), but extending the correlation down to a richness of 5 raises the matching rate to ~65%. Conclusions: This state-of-the-art study involving two well-validated cluster catalogues has shown itself to be complex, and it points to a number of issues inherent to blind cross-matching, owing both to pipeline shortcomings and cluster peculiar properties. These can only been accounted for after a manual check. The combined X-ray and optical scaling relations will be presented in a subsequent article.

Laser scanning endoscope for diagnostic medicine

NASA Astrophysics Data System (ADS)

Ouimette, Donald R.; Nudelman, Sol; Spackman, Thomas; Zaccheo, Scott

1990-07-01

A new type of endoscope is being developed which utilizes an optical raster scanning system for imaging through an endoscope. The optical raster scanner utilizes a high speed, multifaceted, rotating polygon mirror system for horizontal deflection, and a slower speed galvanometer driven mirror as the vertical deflection system. When used in combination, the optical raster scanner traces out a raster similar to an electron beam raster used in television systems. This flying spot of light can then be detected by various types of photosensitive detectors to generate a video image of the surface or scene being illuminated by the scanning beam. The optical raster scanner has been coupled to an endoscope. The raster is projected down the endoscope, thereby illuminating the object to be imaged at the distal end of the endoscope. Elemental photodetectors are placed at the distal or proximal end of the endoscope to detect the reflected illumination from the flying spot of light. This time sequenced signal is captured by an image processor for display and processing. This technique offers the possibility for very small diameter endoscopes since illumination channel requirements are eliminated. Using various lasers, very specific spectral selectivity can be achieved to optimum contrast of specific lesions of interest. Using several laser lines, or a white light source, with detectors of specific spectral response, multiple spectrally selected images can be acquired simultaneously. The potential for co-linear therapy delivery while imaging is also possible.

A geological history of reflecting optics.

PubMed

Parker, Andrew Richard

2005-03-22

Optical reflectors in animals are diverse and ancient. The first image-forming eye appeared around 543 million years ago. This introduced vision as a selection pressure in the evolution of animals, and consequently the evolution of adapted optical devices. The earliest known optical reflectors--diffraction gratings--are 515 Myr old. The subsequent fossil record preserves multilayer reflectors, including liquid crystals and mirrors, 'white' and 'blue' scattering structures, antireflective surfaces and the very latest addition to optical physics--photonic crystals. The aim of this article is to reveal the diversity of reflecting optics in nature, introducing the first appearance of some reflector types as they appear in the fossil record as it stands (which includes many new records) and backdating others in geological time through evolutionary analyses. This article also reveals the commercial potential for these optical devices, in terms of lessons from their nano-level designs and the possible emulation of their engineering processes--molecular self-assembly.

Differential Deposition Technique for Figure Corrections in Grazing Incidence X-ray Optics

NASA Technical Reports Server (NTRS)

Kilaru, Kiranmayee; Ramsey, Brian D.; Gubarev, Mikhail

2009-01-01

A differential deposition technique is being developed to correct the low- and mid-spatial-frequency deviations in the axial figure profile of Wolter type grazing incidence X-ray optics. These deviations arise due to various factors in the fabrication process and they degrade the performance of the optics by limiting the achievable angular resolution. In the differential deposition technique, material of varying thickness is selectively deposited along the length of the optic to minimize these deviations, thereby improving the overall figure. High resolution focusing optics being developed at MSFC for small animal radionuclide imaging are being coated to test the differential deposition technique. The required spatial resolution for these optics is 100 m. This base resolution is achievable with the regular electroform-nickel-replication fabrication technique used at MSFC. However, by improving the figure quality of the optics through differential deposition, we aim at significantly improving the resolution beyond this value.

Studies of Second Order Optical Nonlinearities of 4-Aminobenzophenone (ABP) Single Crystal Films

NASA Astrophysics Data System (ADS)

Bhowmik, Achintya; Thakur, Mrinal

1998-03-01

Specific organic materials exhibit very high second order optical susceptibilities. Growth of single crystal films of these materials and characterization of nonlinear optical properties are necessary for implementation of device applications. We have grown large-area films ( 1 cm^2 area, 4 μm thick) of ABP by a modification of the shear method. Single crystal nature of the films was confirmed by polarized optical microscopy. X-ray diffraction analysis showed a [100] surface orientation. The absorption spectra revealed transparency from 390 nm to 1940 nm. Significant elements of the second order optical susceptibility tensor were measured by detailed SHG experiments using a Nd:YAG laser (1064 nm, 100 ps, 82 MHz). Second-harmonic power was measured using lock-in detection with carefully selected polarization conditions while the film was rotated about the propagation direction. Using LiNbØas the reference, d-coefficients of ABP were found to be d_23=7.2 pm/V and d_22=0.7 pm/V. Type-I and type-II phase-matching directions were identified on the film by analyzing the optical indicatrix surfaces at fundamental and second-harmonic frequencies.

RF kicker cavity to increase control in common transport lines

DOEpatents

Douglas, David R.; Ament, Lucas J. P.

2017-04-18

A method of controlling e-beam transport where electron bunches with different characteristics travel through the same beam pipe. An RF kicker cavity is added at the beginning of the common transport pipe or at various locations along the common transport path to achieve independent control of different bunch types. RF energy is applied by the kicker cavity kicks some portion of the electron bunches, separating the bunches in phase space to allow independent control via optics, or separating bunches into different beam pipes. The RF kicker cavity is operated at a specific frequency to enable kicking of different types of bunches in different directions. The phase of the cavity is set such that the selected type of bunch passes through the cavity when the RF field is at a node, leaving that type of bunch unaffected. Beam optics may be added downstream of the kicker cavity to cause a further separation in phase space.

ICC Type II large-format FPA detector assemblies

NASA Astrophysics Data System (ADS)

Clynne, Thomas H.; Powers, Thomas P.

1997-08-01

ICC presents a new addition to their integrated detector assembly product line with the announcement of their type II large format staring class FPA units. A result of internally funded research and development, the ICC type II detector assembly can accommodate all existing large format staring class PtSi, InSb and MCT focal planes, up to 640 by 480. Proprietary methodologies completely eliminate all FPA stresses to allow for maximum FPA survivability. Standard optical and cryocooler interfaces allow for the use of BEI, AEG, TI SADA Hughes/Magnavox and Joule Thompson coolers. This unit has been qualified to the current SADA II thermal environmental specifications and was tailored around ICC's worldwide industry standard type IV product. Assembled in a real world flexible manufacturing environment, this unit features a wide degree of adaptability and can be easily modified to a user's specifications via standard options and add-ons that include optical interfaces, electrical interfaces and window/filter material selections.

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.

Variability-selected active galactic nuclei in the VST-SUDARE/VOICE survey of the COSMOS field

NASA Astrophysics Data System (ADS)

De Cicco, D.; Paolillo, M.; Covone, G.; Falocco, S.; Longo, G.; Grado, A.; Limatola, L.; Botticella, M. T.; Pignata, G.; Cappellaro, E.; Vaccari, M.; Trevese, D.; Vagnetti, F.; Salvato, M.; Radovich, M.; Brandt, W. N.; Capaccioli, M.; Napolitano, N. R.; Schipani, P.

2015-02-01

Context. Active galaxies are characterized by variability at every wavelength, with timescales from hours to years depending on the observing window. Optical variability has proven to be an effective way of detecting AGNs in imaging surveys, lasting from weeks to years. Aims: In the present work we test the use of optical variability as a tool to identify active galactic nuclei in the VST multiepoch survey of the COSMOS field, originally tailored to detect supernova events. Methods: We make use of the multiwavelength data provided by other COSMOS surveys to discuss the reliability of the method and the nature of our AGN candidates. Results: The selection on the basis of optical variability returns a sample of 83 AGN candidates; based on a number of diagnostics, we conclude that 67 of them are confirmed AGNs (81% purity), 12 are classified as supernovae, while the nature of the remaining 4 is unknown. For the subsample of AGNs with some spectroscopic classification, we find that Type 1 are prevalent (89%) compared to Type 2 AGNs (11%). Overall, our approach is able to retrieve on average 15% of all AGNs in the field identified by means of spectroscopic or X-ray classification, with a strong dependence on the source apparent magnitude (completeness ranging from 26% to 5%). In particular, the completeness for Type 1 AGNs is 25%, while it drops to 6% for Type 2 AGNs. The rest of the X-ray selected AGN population presents on average a larger rms variability than the bulk of non-variable sources, indicating that variability detection for at least some of these objects is prevented only by the photometric accuracy of the data. The low completeness is in part due to the short observing span: we show that increasing the temporal baseline results in larger samples as expected for sources with a red-noise power spectrum. Our results allow us to assess the usefulness of this AGN selection technique in view of future wide-field surveys. Observations were provided by the ESO programs 088.D-0370 and 088.D-4013 (PI G. Pignata).Table 3 is available in electronic form at http://www.aanda.org

Miniaturized fiber-optic Michelson-type interferometric sensors

NASA Technical Reports Server (NTRS)

Murphy, Kent A.; Miller, William V., III; Tran, Tuan A.; Vengsarkar, Ashish M.; Claus, Richard O.

1991-01-01

A novel, miniaturized Michelson-type fiber-optic interferometric sensor that is relatively insensitive to temperature drifts is presented. A fused-biconical tapered coupler is cleaved immediately after the coupled length and polished down to the region of the fused cladding, but short of the interaction region. The end of one core is selectively coated with a reflective surface and is used as the reference arm; the other core serves as the sensing arm. The detection of surface acoustic waves, microdisplacements, and magnetic fields is reported. The sensor is shown to be highly stable in comparison to a classic homodyne, uncompensated Michelson interferometer, and signal-to-noise ratios of 65 dB have been obtained.

VizieR Online Data Catalog: Warm IRAS sources. II. (de Grijp+, 1992)

NASA Astrophysics Data System (ADS)

de Grijp, M. H. K.; Keel, W. C.; Miley, G. K.; Goudfrooij, P.; Lub, J.

2011-01-01

We present optical spectra for a sample of 563 high-latitude IRAS sources selected from the Point Source Catalog to have relatively warm 25 to 60 micron colours. We have shown this selection criterion to be an efficient indicator for finding Seyfert galaxies. Plots of the optical spectra are shown and the fluxes of the strongest emission lines in these spectra are tabulated. After excluding 128 sources which are clearly galactic foreground objects, we obtained spectroscopic information for 358 extragalactic objects. Emission-line ratios have been used to classify these objects, resulting in 80 Seyfert 1, 141 Seyfert 2 and 133 HII-type objects. In comparison with samples of active nuclei selected in other ways, about 50% of known Seyfert nuclei are included by our colour criteria. This fraction is larger for high luminosities, reaching 80% for quasar luminosities. For lower-luminosity objects, contamination by the host galaxies becomes important and the sample becomes seriously incomplete. It should be moderately complete and representative for core luminosities greater than 1023.5W/Hz at 12m. Finally, the infrared luminosity function for each type of object is derived; the shapes for Seyfert 1 and 2 nuclei are identical, with a type 2/type 1 space-density ratio of 3.0. Our census is consistent with an obscuration scheme for producing both types of object from a single parent population, though the origin of excess cool IR radiation Irom many Seyferts is still unclear. We note the appearance of an apparent type II supernova in IRAS 0225-103 observed in 1985 September. Its spectrum suggests that it was observed between 1 and 2 months after maximum, perhaps in a "plateau" phase. (2 data files).

Local Area Networks.

ERIC Educational Resources Information Center

Marks, Kenneth E.; Nielsen, Steven

1991-01-01

Discusses cabling that is needed in local area networks (LANs). Types of cables that may be selected are described, including twisted pair, coaxial cables (or ethernet), and fiber optics; network topologies, the manner in which the cables are laid out, are considered; and cable installation issues are discussed. (LRW)

Atomically precise arrays of fluorescent silver clusters: a modular approach for metal cluster photonics on DNA nanostructures.

PubMed

Copp, Stacy M; Schultz, Danielle E; Swasey, Steven; Gwinn, Elisabeth G

2015-03-24

The remarkable precision that DNA scaffolds provide for arraying nanoscale optical elements enables optical phenomena that arise from interactions of metal nanoparticles, dye molecules, and quantum dots placed at nanoscale separations. However, control of ensemble optical properties has been limited by the difficulty of achieving uniform particle sizes and shapes. Ligand-stabilized metal clusters offer a route to atomically precise arrays that combine desirable attributes of both metals and molecules. Exploiting the unique advantages of the cluster regime requires techniques to realize controlled nanoscale placement of select cluster structures. Here we show that atomically monodisperse arrays of fluorescent, DNA-stabilized silver clusters can be realized on a prototypical scaffold, a DNA nanotube, with attachment sites separated by <10 nm. Cluster attachment is mediated by designed DNA linkers that enable isolation of specific clusters prior to assembly on nanotubes and preserve cluster structure and spectral purity after assembly. The modularity of this approach generalizes to silver clusters of diverse sizes and DNA scaffolds of many types. Thus, these silver cluster nano-optical elements, which themselves have colors selected by their particular DNA templating oligomer, bring unique dimensions of control and flexibility to the rapidly expanding field of nano-optics.

Practical Aspects of Access Network Indoor Extensions Using Multimode Glass and Plastic Optical Fibers

NASA Astrophysics Data System (ADS)

Keiser, Gerd; Liu, Hao-Yu; Lu, Shao-Hsi; Devi Pukhrambam, Puspa

2012-07-01

Low-cost multimode glass and plastic optical fibers are attractive for high-capacity indoor telecom networks. Many existing buildings already have glass multimode fibers installed for local area network applications. Future indoor applications will use combinations of glass multimode fibers with plastic optical fibers that have low losses in the 850-nm-1,310-nm range. This article examines real-world link losses when randomly interconnecting glass and plastic fiber segments having factory-installed connectors. Potential interconnection issues include large variations in connector losses among randomly selected fiber segments, asymmetric link losses in bidirectional links, and variations in bandwidths among different types of fibers.

Real-Space Mapping of the Chiral Near-Field Distributions in Spiral Antennas and Planar Metasurfaces.

PubMed

Schnell, M; Sarriugarte, P; Neuman, T; Khanikaev, A B; Shvets, G; Aizpurua, J; Hillenbrand, R

2016-01-13

Chiral antennas and metasurfaces can be designed to react differently to left- and right-handed circularly polarized light, which enables novel optical properties such as giant optical activity and negative refraction. Here, we demonstrate that the underlying chiral near-field distributions can be directly mapped with scattering-type scanning near-field optical microscopy employing circularly polarized illumination. We apply our technique to visualize, for the first time, the circular-polarization selective nanofocusing of infrared light in Archimedean spiral antennas, and explain this chiral optical effect by directional launching of traveling waves in analogy to antenna theory. Moreover, we near-field image single-layer rosette and asymmetric dipole-monopole metasurfaces and find negligible and strong chiral optical near-field contrast, respectively. Our technique paves the way for near-field characterization of optical chirality in metal nanostructures, which will be essential for the future development of chiral antennas and metasurfaces and their applications.

Simultaneous topography and tomography of latent fingerprints using full-field swept-source optical coherence tomography

NASA Astrophysics Data System (ADS)

Dubey, Satish Kumar; Singh Mehta, Dalip; Anand, Arun; Shakher, Chandra

2008-01-01

We demonstrate simultaneous topography and tomography of latent fingerprints using full-field swept-source optical coherence tomography (OCT). The swept-source OCT system comprises a superluminescent diode (SLD) as broad-band light source, an acousto-optic tunable filter (AOTF) as frequency tuning device, and a compact, nearly common-path interferometer. Both the amplitude and the phase map of the interference fringe signal are reconstructed. Optical sectioning of the latent fingerprint sample is obtained by selective Fourier filtering and the topography is retrieved from the phase map. Interferometry, selective filtering, low coherence and hence better resolution are some of the advantages of the proposed system over the conventional fingerprint detection techniques. The present technique is non-invasive in nature and does not require any physical or chemical processing. Therefore, the quality of the sample does not alter and hence the same fingerprint can be used for other types of forensic test. Exploitation of low-coherence interferometry for fingerprint detection itself provides an edge over other existing techniques as fingerprints can even be lifted from low-reflecting surfaces. The proposed system is very economical and compact.

Dark field photoelectron emission microscopy of micron scale few layer graphene

NASA Astrophysics Data System (ADS)

Barrett, N.; Conrad, E.; Winkler, K.; Krömker, B.

2012-08-01

We demonstrate dark field imaging in photoelectron emission microscopy (PEEM) of heterogeneous few layer graphene (FLG) furnace grown on SiC(000-1). Energy-filtered, threshold PEEM is used to locate distinct zones of FLG graphene. In each region, selected by a field aperture, the k-space information is imaged using appropriate transfer optics. By selecting the photoelectron intensity at a given wave vector and using the inverse transfer optics, dark field PEEM gives a spatial distribution of the angular photoelectron emission. In the results presented here, the wave vector coordinates of the Dirac cones characteristic of commensurate rotations of FLG on SiC(000-1) are selected providing a map of the commensurate rotations across the surface. This special type of contrast is therefore a method to map the spatial distribution of the local band structure and offers a new laboratory tool for the characterisation of technically relevant, microscopically structured matter.

Diffractive optics in large sizes: computer-generated holograms (CGH) based on Bayfol HX photopolymer

NASA Astrophysics Data System (ADS)

Bruder, Friedrich-Karl; Fäcke, Thomas; Hagen, Rainer; Hönel, Dennis; Kleinschmidt, Tim Patrick; Orselli, Enrico; Rewitz, Christian; Rölle, Thomas; Walze, Günther

2015-03-01

Volume Holographic Optical Elements (vHOE) offer angular and spectral Bragg selectivity that can be tuned by film thickness and holographic recording conditions. With the option to integrate complex optical function in a very thin plastic layer formerly heavy refractive optics can be made thin and lightweight especially for large area applications like liquid crystal displays, projection screens or photovoltaic. Additionally their Bragg selectivity enables the integration of several completely separated optical functions in the same film. The new instant developing photopolymer film (Bayfol® HX) paves the way towards new cost effective diffractive large optics, due to its easy holographic recording and environmental stability. A major bottleneck for large area applications has been the master hologram recording which traditionally needs expensive, large high precision optical equipment and high power laser with long coherence length. Further the recording setup needs to be rearranged for a change in optical design. In this paper we describe an alternative method for large area holographic master recording, using standard optics and low power lasers in combination with an x, y-translation stage. In this setup small sub-holograms generated by a phase only spatial light modulator (SLM) are recorded next to each other to generate a large size vHOE. The setup is flexible to generate various types of HOEs without the need of a change in the mechanical and optical construction by convenient SLM programming. One Application example and parameter studies for printed vHOEs based on Bayfol® HX Photopolymer will be given.

Fabrication and characterization of a nanometer-sized optical fiber electrode based on selective chemical etching for scanning electrochemical/optical microscopy.

PubMed

Maruyama, Kenichi; Ohkawa, Hiroyuki; Ogawa, Sho; Ueda, Akio; Niwa, Osamu; Suzuki, Koji

2006-03-15

We have already reported a method for fabricating ultramicroelectrodes (Suzuki, K. JP Patent, 2004-45394, 2004). This method is based on the selective chemical etching of optical fibers. In this work, we undertake a detailed investigation involving a combination of etched optical fibers with various types of tapered tip (protruding-shape, double- (or pencil-) shape and triple-tapered electrode) and insulation with electrophoretic paint. Our goal is to establish a method for fabricating nanometer-sized optical fiber electrodes with high reproducibility. As a result, we realized pencil-shaped and triple-tapered electrodes that had radii in the nanometer range with high reproducibility. These nanometer-sized electrodes showed well-defined sigmoidal curves and stable diffusion-limited responses with cyclic voltammetry. The pencil-shaped optical fiber, which has a conical tip with a cone angle of 20 degrees , was effective for controlling the electrode radius. The pencil-shaped electrodes had higher reproducibility and smaller electrode radii (r(app) < 1.0 nm) than those of other etched optical fiber electrodes. By using a pencil-shaped electrode with a 105-nm radius as a probe, we obtained simultaneous electrochemical and optical images of an implantable interdigitated array electrode. We achieved nanometer-scale resolution with a combination of scanning electrochemical microscopy SECM and optical microscopy. The resolution of the electrochemical and optical images indicated sizes of 300 and 930 nm, respectively. The neurites of living PC12 cells were also successfully imaged on a 1.6-microm scale by using the negative feedback mode of an SECM.

Development Of The Drexler Optical-Card Reader/Writer System

NASA Astrophysics Data System (ADS)

Pierce, Gerald A.

1988-06-01

An optical-card reader/writer optical and electronic breadboard system, developed by SRI International under contract to Drexler Technology, is described. The optical card, which is the same size as a credit card, can contain more than 2 megabytes of digital user data, which may also include preformatted tracking information and preformatted data. The data layout on the card is similar to that on a floppy disk, with each track containing a header and clocking information. The design of this optical reader/writer system for optical cards is explained. Design of the optical card system entails a number of unique issues: To accommodate both laser-recorded and mass-duplicated information, the system must be compatible with preencoded information, which implies a larger-than-normal spot size (5 gm) and a detection system that can read both types of optical patterns. Cost-reduction considerations led to selection of a birefringent protection layer, which dictated a nonstandard optical system. The non-polarization-sensitive optics use an off-axis approach to detection. An LED illumination system makes it possible to read multiple tracks.

All optical wavelength broadcast based on simultaneous Type I QPM broadband SFG and SHG in MgO:PPLN.

PubMed

Gong, Mingjun; Chen, Yuping; Lu, Feng; Chen, Xianfeng

2010-08-15

We experimentally demonstrate wavelength broadcast based on simultaneous Type I quasi-phase-matched (QPM) broadband sum-frequency generation (SFG) and second-harmonic generation (SHG) in 5 mol.% MgO-doped periodically poled lithium niobate (MgO:PPLN). One signal has been synchronously converted into seven different wavelengths using two pumps at a 1.5 microm band via quadratic cascaded nonlinear wavelength conversion. By selecting different pump regions, i.e., selecting different cascaded chi((2)):chi((2)) interactions, the flexible wavelength conversions with shifting from one signal to single, double, and triple channels were also demonstrated.

A Real-Time Method to Estimate Speed of Object Based on Object Detection and Optical Flow Calculation

NASA Astrophysics Data System (ADS)

Liu, Kaizhan; Ye, Yunming; Li, Xutao; Li, Yan

2018-04-01

In recent years Convolutional Neural Network (CNN) has been widely used in computer vision field and makes great progress in lots of contents like object detection and classification. Even so, combining Convolutional Neural Network, which means making multiple CNN frameworks working synchronously and sharing their output information, could figure out useful message that each of them cannot provide singly. Here we introduce a method to real-time estimate speed of object by combining two CNN: YOLOv2 and FlowNet. In every frame, YOLOv2 provides object size; object location and object type while FlowNet providing the optical flow of whole image. On one hand, object size and object location help to select out the object part of optical flow image thus calculating out the average optical flow of every object. On the other hand, object type and object size help to figure out the relationship between optical flow and true speed by means of optics theory and priori knowledge. Therefore, with these two key information, speed of object can be estimated. This method manages to estimate multiple objects at real-time speed by only using a normal camera even in moving status, whose error is acceptable in most application fields like manless driving or robot vision.

A geological history of reflecting optics

PubMed Central

Parker, Andrew Richard

2005-01-01

Optical reflectors in animals are diverse and ancient. The first image-forming eye appeared around 543 million years ago. This introduced vision as a selection pressure in the evolution of animals, and consequently the evolution of adapted optical devices. The earliest known optical reflectors—diffraction gratings—are 515 Myr old. The subsequent fossil record preserves multilayer reflectors, including liquid crystals and mirrors, ‘white’ and ‘blue’ scattering structures, antireflective surfaces and the very latest addition to optical physics—photonic crystals. The aim of this article is to reveal the diversity of reflecting optics in nature, introducing the first appearance of some reflector types as they appear in the fossil record as it stands (which includes many new records) and backdating others in geological time through evolutionary analyses. This article also reveals the commercial potential for these optical devices, in terms of lessons from their nano-level designs and the possible emulation of their engineering processes—molecular self-assembly. PMID:16849159

Optical–Mid-infrared Period–Luminosity Relations for W UMa-type Contact Binaries Based on Gaia DR 1: 8% Distance Accuracy

NASA Astrophysics Data System (ADS)

Chen, Xiaodian; Deng, Licai; de Grijs, Richard; Wang, Shu; Feng, Yuting

2018-06-01

W Ursa Majoris (W UMa)-type contact binary systems (CBs) are useful statistical distance indicators because of their large numbers. Here, we establish (orbital) period–luminosity relations (PLRs) in 12 optical to mid-infrared bands (GBVRIJHK s W1W2W3W4) based on 183 nearby W UMa-type CBs with accurate Tycho–Gaia parallaxes. The 1σ dispersion of the PLRs decreases from optical to near- and mid-infrared wavelengths. The minimum scatter, 0.16 mag, implies that W UMa-type CBs can be used to recover distances to 7% precision. Applying our newly determined PLRs to 19 open clusters containing W UMa-type CBs demonstrates that the PLR and open cluster CB distance scales are mutually consistent to within 1%. Adopting our PLRs as secondary distance indicators, we compiled a catalog of 55,603 CB candidates, of which 80% have distance estimates based on a combination of optical, near-infrared, and mid-infrared photometry. Using Fourier decomposition, 27,318 high-probability W UMa-type CBs were selected. The resulting 8% distance accuracy implies that our sample encompasses the largest number of objects with accurate distances within a local volume with a radius of 3 kpc available to date. The distribution of W UMa-type CBs in the Galaxy suggests that in different environments, the CB luminosity function may be different: larger numbers of brighter (longer-period) W UMa-type CBs are found in younger environments.

The Ultracool Typing Kit - An Open-Source, Qualitative Spectral Typing GUI for L Dwarfs

NASA Astrophysics Data System (ADS)

Schwab, Ellianna; Cruz, Kelle; Núñez, Alejandro; Burgasser, Adam J.; Rice, Emily; Reid, Neill; Faherty, Jacqueline K.; BDNYC

2018-01-01

The Ultracool Typing Kit (UTK) is an open-source graphical user interface for classifying the NIR spectral types of L dwarfs, including field and low-gravity dwarfs spanning L0-L9. The user is able to input an NIR spectrum and qualitatively compare the input spectrum to a full suite of spectral templates, including low-gravity beta and gamma templates. The user can choose to view the input spectrum as both a band-by-band comparison with the templates and a full bandwidth comparison with NIR spectral standards. Once an optimal qualitative comparison is selected, the user can save their spectral type selection both graphically and to a database. Using UTK to classify 78 previously typed L dwarfs, we show that a band-by-band classification method more accurately agrees with optical spectral typing systems than previous L dwarf NIR classification schemes. UTK is written in python, released on Zenodo with a BSD-3 clause license and publicly available on the BDNYC Github page.

Space Density Of Optically-Selected Type II Quasars From The SDSS

NASA Astrophysics Data System (ADS)

Reyes, Reinabelle; Zakamska, N. L.; Strauss, M. A.; Green, J.; Krolik, J. H.; Shen, Y.; Richards, G. T.

2007-12-01

Type II quasars are luminous Active Galactic Nuclei (AGN) whose central regions are obscured by large amounts of gas and dust. In this poster, we present a catalog of 887 type II quasars with redshifts z<0.83 from the Sloan Digital Sky Survey (SDSS), selected based on their emission lines, and derive the 1/Vmax [OIII] 5007 luminosity function from this sample. Since some objects may not be included in the sample because they lack strong emission lines, the derived luminosity function is only a lower limit. We also derive the [OIII] 5007 luminosity function for a sample of type I (broad-line) quasars in the same redshift range. Taking [OIII] 5007 luminosity as a tracer of intrinsic luminosity in both type I and type II quasars, we obtain lower limits to the type II quasar fraction as a function of [OIII] 5007 luminosity, from L[OIII] = 108.3 to 1010 Lsun, which roughly correspond to bolometric luminosities of 1044 to 1046 erg/s.

Spectral classification of selected ISOGAL sources using Himalayan Chandra Telescope

NASA Astrophysics Data System (ADS)

Joshi, U. C.; Ganesh, S.; Baliyan, K. S.; Parthasarathy, M.; Schultheis, M.; Rajpurohit, A.; Simon, G.; Omont, A.

The ISOGAL survey (Omont et al. 1999) is devoted to the observation of selected regions of the Galactic plane in the mid-infrared with ISOCAM. More than 240 fields were observed at 7 and 15 micron wave-bands with ISOCAM at an angular resolution of 6'' which has provided a complete census, in the areas surveyed, of the stars in the late stages (RGB/AGB phases) of stellar evolution. Optical counterparts are detected for some of the ISOGAL sources in the directions where the extinction is relatively lower. We obtained optical spectra of ˜100 such sources with the Himalayan Chandra Telescope (HCT), India and estimated their spectral classes. Optical spectroscopy together with mid-IR data is expected to allow us to obtain the spectral-type vs mass-loss relation which are important parameters to understand the late stages of stellar evolution. In this paper, we present a set of spectra taken in the field FC97 for which ISOGAL survey is complete.

Functional architecture of an optic flow-responsive area that drives horizontal eye movements in zebrafish.

PubMed

Kubo, Fumi; Hablitzel, Bastian; Dal Maschio, Marco; Driever, Wolfgang; Baier, Herwig; Arrenberg, Aristides B

2014-03-19

Animals respond to whole-field visual motion with compensatory eye and body movements in order to stabilize both their gaze and position with respect to their surroundings. In zebrafish, rotational stimuli need to be distinguished from translational stimuli to drive the optokinetic and the optomotor responses, respectively. Here, we systematically characterize the neural circuits responsible for these operations using a combination of optogenetic manipulation and in vivo calcium imaging during optic flow stimulation. By recording the activity of thousands of neurons within the area pretectalis (APT), we find four bilateral pairs of clusters that process horizontal whole-field motion and functionally classify eleven prominent neuron types with highly selective response profiles. APT neurons are prevalently direction selective, either monocularly or binocularly driven, and hierarchically organized to distinguish between rotational and translational optic flow. Our data predict a wiring diagram of a neural circuit tailored to drive behavior that compensates for self-motion. Copyright © 2014 Elsevier Inc. All rights reserved.

DISCOVERING BRIGHT QUASARS AT INTERMEDIATE REDSHIFTS BASED ON OPTICAL/NEAR-INFRARED COLORS

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

Wu, Xue-Bing; Zuo, Wenwen; Yang, Jinyi

2013-10-01

The identification of quasars at intermediate redshifts (2.2 < z < 3.5) has been inefficient in most previous quasar surveys since the optical colors of quasars are similar to those of stars. The near-IR K-band excess technique has been suggested to overcome this difficulty. Our recent study also proposed to use optical/near-IR colors for selecting z < 4 quasars. To verify the effectiveness of this method, we selected a list of 105 unidentified bright targets with i ≤ 18.5 from the quasar candidates of SDSS DR6 with both SDSS ugriz optical and UKIDSS YJHK near-IR photometric data, which satisfy ourmore » proposed Y – K/g – z criterion and have photometric redshifts between 2.2 and 3.5 estimated from the nine-band SDSS-UKIDSS data. We observed 43 targets with the BFOSC instrument on the 2.16 m optical telescope at Xinglong station of the National Astronomical Observatory of China in the spring of 2012. We spectroscopically identified 36 targets as quasars with redshifts between 2.1 and 3.4. The high success rate of discovering these quasars in the SDSS spectroscopic surveyed area further demonstrates the robustness of both the Y – K/g – z selection criterion and the photometric redshift estimation technique. We also used the above criterion to investigate the possible stellar contamination rate among the quasar candidates of SDSS DR6, and found that the rate is much higher when selecting 3 < z < 3.5 quasar candidates than when selecting lower redshift candidates (z < 2.2). The significant improvement in the photometric redshift estimation when using the nine-band SDSS-UKIDSS data over the five-band SDSS data is demonstrated and a catalog of 7727 unidentified quasar candidates in SDSS DR6 selected with optical/near-IR colors and having photometric redshifts between 2.2 and 3.5 is provided. We also tested the Y – K/g – z selection criterion with the recently released SDSS-III/DR9 quasar catalog and found that 96.2% of 17,999 DR9 quasars with UKIDSS Y- and K-band data satisfy our criterion. With some available samples of red quasars and type II quasars, we find that 88% and 96.5% of these objects can be selected by the Y – K/g – z criterion, respectively, which supports our claim that using the Y – K/g – z criterion efficiently selects both unobscured and obscured quasars. We discuss the implications of our results on the ongoing and upcoming large optical and near-IR sky surveys.« less

Enhanced Optical Transmission Mediated by Localized Plasmons in Anisotropic, 3D Nanohole Arrays

PubMed Central

Yang, Jiun-Chan; Gao, Hanwei; Suh, Jae Yong; Zhou, Wei; Lee, Min Hyung; Odom, Teri W.

2010-01-01

This paper describes 3D nanohole arrays whose high optical transmission is mediated more by localized surface plasmon (LSP) excitations than by surface plasmon polaritons (SPPs). First, LSPs on 3D hole arrays lead to optical transmission an order of magnitude higher than 2D planar hole arrays. Second, LSP-mediated transmission is broadband and more tunable than SPP-enhanced transmission which is restricted by Bragg coupling. Third, for the first time, two types of surface plasmons can be selectively excited and manipulated on the same plasmonic substrate. This new plasmonic substrate fabricated by high-throughput nanolithography techniques paves the way for cutting-edge optoelectronic and biomedical applications. PMID:20698633

Minimal residual method provides optimal regularization parameter for diffuse optical tomography

NASA Astrophysics Data System (ADS)

Jagannath, Ravi Prasad K.; Yalavarthy, Phaneendra K.

2012-10-01

The inverse problem in the diffuse optical tomography is known to be nonlinear, ill-posed, and sometimes under-determined, requiring regularization to obtain meaningful results, with Tikhonov-type regularization being the most popular one. The choice of this regularization parameter dictates the reconstructed optical image quality and is typically chosen empirically or based on prior experience. An automated method for optimal selection of regularization parameter that is based on regularized minimal residual method (MRM) is proposed and is compared with the traditional generalized cross-validation method. The results obtained using numerical and gelatin phantom data indicate that the MRM-based method is capable of providing the optimal regularization parameter.

Minimal residual method provides optimal regularization parameter for diffuse optical tomography.

PubMed

Jagannath, Ravi Prasad K; Yalavarthy, Phaneendra K

2012-10-01

The inverse problem in the diffuse optical tomography is known to be nonlinear, ill-posed, and sometimes under-determined, requiring regularization to obtain meaningful results, with Tikhonov-type regularization being the most popular one. The choice of this regularization parameter dictates the reconstructed optical image quality and is typically chosen empirically or based on prior experience. An automated method for optimal selection of regularization parameter that is based on regularized minimal residual method (MRM) is proposed and is compared with the traditional generalized cross-validation method. The results obtained using numerical and gelatin phantom data indicate that the MRM-based method is capable of providing the optimal regularization parameter.

Optically active single-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Peng, Xiaobin; Komatsu, Naoki; Bhattacharya, Sumanta; Shimawaki, Takanori; Aonuma, Shuji; Kimura, Takahide; Osuka, Atsuhiro

2007-06-01

The optical, electrical and mechanical properties of single-walled carbon nanotubes (SWNTs) are largely determined by their structures, and bulk availability of uniform materials is vital for extending their technological applications. Since they were first prepared, much effort has been directed toward selective synthesis and separation of SWNTs with specific structures. As-prepared samples of chiral SWNTs contain equal amounts of left- and right-handed helical structures, but little attention has been paid to the separation of these non-superimposable mirror image forms, known as optical isomers. Here, we show that optically active SWNT samples can be obtained by preferentially extracting either right- or left-handed SWNTs from a commercial sample. Chiral `gable-type' diporphyrin molecules bind with different affinities to the left- and right-handed helical nanotube isomers to form complexes with unequal stabilities that can be readily separated. Significantly, the diporphyrins can be liberated from the complexes afterwards, to provide optically enriched SWNTs.

Phase-selective vanadium dioxide (VO2) nanostructured thin films by pulsed laser deposition

NASA Astrophysics Data System (ADS)

Masina, B. N.; Lafane, S.; Wu, L.; Akande, A. A.; Mwakikunga, B.; Abdelli-Messaci, S.; Kerdja, T.; Forbes, A.

2015-10-01

Thin films of monoclinic nanostructured vanadium dioxide are notoriously difficult to produce in a selective manner. To date, post-annealing, after pulsed laser deposition (PLD), has been used to revert the crystal phase or to remove impurities, and non-glass substrates have been employed, thus reducing the efficacy of the transparency switching. Here, we overcome these limitations in PLD by optimizing a laser-ablation and deposition process through optical imaging of the laser-induced plasma. We report high quality monoclinic rutile-type vanadium dioxide (VO2) (M1) nanoparticles without post-annealing, and on a glass substrate. Our samples demonstrate a reversible metal-to-insulator transition at ˜43 °C, without any doping, paving the way to switchable transparency in optical materials at room temperature.

Highly spectrum-selective ultraviolet photodetector based on p-NiO/n-IGZO thin film heterojunction structure.

PubMed

Li, H K; Chen, T P; Hu, S G; Li, X D; Liu, Y; Lee, P S; Wang, X P; Li, H Y; Lo, G Q

2015-10-19

Ultraviolet photodetector with p-n heterojunction is fabricated by magnetron sputtering deposition of n-type indium gallium zinc oxide (n-IGZO) and p-type nickel oxide (p-NiO) thin films on ITO glass. The performance of the photodetector is largely affected by the conductivity of the p-NiO thin film, which can be controlled by varying the oxygen partial pressure during the deposition of the p-NiO thin film. A highly spectrum-selective ultraviolet photodetector has been achieved with the p-NiO layer with a high conductivity. The results can be explained in terms of the "optically-filtering" function of the NiO layer.

The NuSTAR Serendipitous Survey: The 40-month Catalog and the Properties of the Distant High-energy X-Ray Source Population

NASA Astrophysics Data System (ADS)

Lansbury, G. B.; Stern, D.; Aird, J.; Alexander, D. M.; Fuentes, C.; Harrison, F. A.; Treister, E.; Bauer, F. E.; Tomsick, J. A.; Baloković, M.; Del Moro, A.; Gandhi, P.; Ajello, M.; Annuar, A.; Ballantyne, D. R.; Boggs, S. E.; Brandt, W. N.; Brightman, M.; Chen, C.-T. J.; Christensen, F. E.; Civano, F.; Comastri, A.; Craig, W. W.; Forster, K.; Grefenstette, B. W.; Hailey, C. J.; Hickox, R. C.; Jiang, B.; Jun, H. D.; Koss, M.; Marchesi, S.; Melo, A. D.; Mullaney, J. R.; Noirot, G.; Schulze, S.; Walton, D. J.; Zappacosta, L.; Zhang, W. W.

2017-02-01

We present the first full catalog and science results for the Nuclear Spectroscopic Telescope Array (NuSTAR) serendipitous survey. The catalog incorporates data taken during the first 40 months of NuSTAR operation, which provide ≈20 Ms of effective exposure time over 331 fields, with an areal coverage of 13 deg2, and 497 sources detected in total over the 3-24 keV energy range. There are 276 sources with spectroscopic redshifts and classifications, largely resulting from our extensive campaign of ground-based spectroscopic follow-up. We characterize the overall sample in terms of the X-ray, optical, and infrared source properties. The sample is primarily composed of active galactic nuclei (AGNs), detected over a large range in redshift from z = 0.002 to 3.4 (median of < z> =0.56), but also includes 16 spectroscopically confirmed Galactic sources. There is a large range in X-ray flux, from {log}({f}3-24{keV}/{erg} {{{s}}}-1 {{cm}}-2)≈ -14 to -11, and in rest-frame 10-40 keV luminosity, from {log}({L}10-40{keV}/{erg} {{{s}}}-1)≈ 39 to 46, with a median of 44.1. Approximately 79% of the NuSTAR sources have lower-energy (<10 keV) X-ray counterparts from XMM-Newton, Chandra, and Swift XRT. The mid-infrared (MIR) analysis, using WISE all-sky survey data, shows that MIR AGN color selections miss a large fraction of the NuSTAR-selected AGN population, from ≈15% at the highest luminosities ({L}{{X}}> {10}44 erg s-1) to ≈80% at the lowest luminosities ({L}{{X}}< {10}43 erg s-1). Our optical spectroscopic analysis finds that the observed fraction of optically obscured AGNs (I.e., the type 2 fraction) is {F}{Type2}={53}-15+14 % , for a well-defined subset of the 8-24 keV selected sample. This is higher, albeit at a low significance level, than the type 2 fraction measured for redshift- and luminosity-matched AGNs selected by <10 keV X-ray missions.

First Searches for Optical Counterparts to Gravitational-wave Candidate Events

NASA Astrophysics Data System (ADS)

Aasi, J.; Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Accadia, T.; Acernese, F.; Adams, C.; Adams, T.; Adhikari, R. X.; Affeldt, C.; Agathos, M.; Aggarwal, N.; Aguiar, O. D.; Ajith, P.; Allen, B.; Allocca, A.; Amador Ceron, E.; Amariutei, D.; Anderson, R. A.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C.; Areeda, J.; Ast, S.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Austin, L.; Aylott, B. E.; Babak, S.; Baker, P. T.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barker, D.; Barnum, S. H.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barton, M. A.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J.; Bauchrowitz, J.; Bauer, Th. S.; Bebronne, M.; Behnke, B.; Bejger, M.; Beker, M. G.; Bell, A. S.; Bell, C.; Belopolski, I.; Bergmann, G.; Berliner, J. M.; Bertolini, A.; Bessis, D.; Betzwieser, J.; Beyersdorf, P. T.; Bhadbhade, T.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Bitossi, M.; Bizouard, M. A.; Black, E.; Blackburn, J. K.; Blackburn, L.; Blair, D.; Blom, M.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogan, C.; Bond, C.; Bondu, F.; Bonelli, L.; Bonnand, R.; Bork, R.; Born, M.; Bose, S.; Bosi, L.; Bowers, J.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brannen, C. A.; Brau, J. E.; Breyer, J.; Briant, T.; Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Britzger, M.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brückner, F.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Calderón Bustillo, J.; Calloni, E.; Camp, J. B.; Campsie, P.; Cannon, K. C.; Canuel, B.; Cao, J.; Capano, C. D.; Carbognani, F.; Carbone, L.; Caride, S.; Castiglia, A.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chen, X.; Chen, Y.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Chow, J.; Christensen, N.; Chu, Q.; Chua, S. S. Y.; Chung, S.; Ciani, G.; Clara, F.; Clark, D. E.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Colombini, M.; Constancio, M., Jr.; Conte, A.; Conte, R.; Cook, D.; Corbitt, T. R.; Cordier, M.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M. W.; Coulon, J.-P.; Countryman, S.; Couvares, P.; Coward, D. M.; Cowart, M.; Coyne, D. C.; Craig, K.; Creighton, J. D. E.; Creighton, T. D.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dahl, K.; Dal Canton, T.; Damjanic, M.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dattilo, V.; Daudert, B.; Daveloza, H.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; Dayanga, T.; De Rosa, R.; Debreczeni, G.; Degallaix, J.; Del Pozzo, W.; Deleeuw, E.; Deléglise, S.; Denker, T.; Dereli, H.; Dergachev, V.; DeRosa, R.; DeSalvo, R.; Dhurandhar, S.; Di Fiore, L.; Di Lieto, A.; Di Palma, I.; Di Virgilio, A.; Díaz, M.; Dietz, A.; Dmitry, K.; Donovan, F.; Dooley, K. L.; Doravari, S.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Dumas, J.-C.; Dwyer, S.; Eberle, T.; Edwards, M.; Effler, A.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Endrőczi, G.; Essick, R.; Etzel, T.; Evans, K.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst, S.; Fang, Q.; Farr, B.; Farr, W.; Favata, M.; Fazi, D.; Fehrmann, H.; Feldbaum, D.; Ferrante, I.; Ferrini, F.; Fidecaro, F.; Finn, L. S.; Fiori, I.; Fisher, R.; Flaminio, R.; Foley, E.; Foley, S.; Forsi, E.; Forte, L. A.; Fotopoulos, N.; Fournier, J.-D.; Franco, S.; Frasca, S.; Frasconi, F.; Frede, M.; Frei, M.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fujimoto, M.-K.; Fulda, P.; Fyffe, M.; Gair, J.; Gammaitoni, L.; Garcia, J.; Garufi, F.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; Gergely, L.; Ghosh, S.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Giazotto, A.; Gil-Casanova, S.; Gill, C.; Gleason, J.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gordon, N.; Gorodetsky, M. L.; Gossan, S.; Goßler, S.; Gouaty, R.; Graef, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Griffo, C.; Grote, H.; Grover, K.; Grunewald, S.; Guidi, G. M.; Guido, C.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hall, B.; Hall, E.; Hammer, D.; Hammond, G.; Hanke, M.; Hanks, J.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G. M.; Harry, I. W.; Harstad, E. D.; Hartman, M. T.; Haughian, K.; Hayama, K.; Heefner, J.; Heidmann, A.; Heintze, M.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Holt, K.; Holtrop, M.; Hong, T.; Hooper, S.; Horrom, T.; Hosken, D. J.; Hough, J.; Howell, E. J.; Hu, Y.; Hua, Z.; Huang, V.; Huerta, E. A.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh, M.; Huynh-Dinh, T.; Iafrate, J.; Ingram, D. R.; Inta, R.; Isogai, T.; Ivanov, A.; Iyer, B. R.; Izumi, K.; Jacobson, M.; James, E.; Jang, H.; Jang, Y. J.; Jaranowski, P.; Jiménez-Forteza, F.; Johnson, W. W.; Jones, D.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; K, Haris; Kalmus, P.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Kasprzack, M.; Kasturi, R.; Katsavounidis, E.; Katzman, W.; Kaufer, H.; Kaufman, K.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Kéfélian, F.; Keitel, D.; Kelley, D. B.; Kells, W.; Keppel, D. G.; Khalaidovski, A.; Khalili, F. Y.; Khazanov, E. A.; Kim, B. K.; Kim, C.; Kim, K.; Kim, N.; Kim, W.; Kim, Y.-M.; King, E. J.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Klimenko, S.; Kline, J.; Koehlenbeck, S.; Kokeyama, K.; Kondrashov, V.; Koranda, S.; Korth, W. Z.; Kowalska, I.; Kozak, D.; Kremin, A.; Kringel, V.; Krishnan, B.; Królak, A.; Kucharczyk, C.; Kudla, S.; Kuehn, G.; Kumar, A.; Kumar, P.; Kumar, R.; Kurdyumov, R.; Kwee, P.; Landry, M.; Lantz, B.; Larson, S.; Lasky, P. D.; Lawrie, C.; Lazzarini, A.; Le Roux, A.; Leaci, P.; Lebigot, E. O.; Lee, C.-H.; Lee, H. K.; Lee, H. M.; Lee, J.; Lee, J.; Leonardi, M.; Leong, J. R.; Leroy, N.; Letendre, N.; Levine, B.; Lewis, J. B.; Lhuillier, V.; Li, T. G. F.; Lin, A. C.; Littenberg, T. B.; Litvine, V.; Liu, F.; Liu, H.; Liu, Y.; Liu, Z.; Lloyd, D.; Lockerbie, N. A.; Lockett, V.; Lodhia, D.; Loew, K.; Logue, J.; Lombardi, A. L.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J.; Luan, J.; Lubinski, M. J.; Lück, H.; Lundgren, A. P.; Macarthur, J.; Macdonald, E.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magana-Sandoval, F.; Mageswaran, M.; Mailand, K.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Manca, G. M.; Mandel, I.; Mandic, V.; Mangano, V.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markosyan, A.; Maros, E.; Marque, J.; Martelli, F.; Martin, I. W.; Martin, R. M.; Martinelli, L.; Martynov, D.; Marx, J. N.; Mason, K.; Masserot, A.; Massinger, T. J.; Matichard, F.; Matone, L.; Matzner, R. A.; Mavalvala, N.; May, G.; Mazumder, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.; McGuire, S. C.; McIntyre, G.; McIver, J.; Meacher, D.; Meadors, G. D.; Mehmet, M.; Meidam, J.; Meier, T.; Melatos, A.; Mendell, G.; Mercer, R. A.; Meshkov, S.; Messenger, C.; Meyer, M. S.; Miao, H.; Michel, C.; Mikhailov, E. E.; Milano, L.; Miller, J.; Minenkov, Y.; Mingarelli, C. M. F.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moe, B.; Mohan, M.; Mohapatra, S. R. P.; Mokler, F.; Moraru, D.; Moreno, G.; Morgado, N.; Mori, T.; Morriss, S. R.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, C. L.; Mueller, G.; Mukherjee, S.; Mullavey, A.; Munch, J.; Murphy, D.; Murray, P. G.; Mytidis, A.; Nagy, M. F.; Nanda Kumar, D.; Nardecchia, I.; Nash, T.; Naticchioni, L.; Nayak, R.; Necula, V.; Neri, I.; Newton, G.; Nguyen, T.; Nishida, E.; Nishizawa, A.; Nitz, A.; Nocera, F.; Nolting, D.; Normandin, M. E.; Nuttall, L. K.; Ochsner, E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Oppermann, P.; O'Reilly, B.; Ortega Larcher, W.; O'Shaughnessy, R.; Osthelder, C.; Ottaway, D. J.; Ottens, R. S.; Ou, J.; Overmier, H.; Owen, B. J.; Padilla, C.; Pai, A.; Palomba, C.; Pan, Y.; Pankow, C.; Paoletti, F.; Paoletti, R.; Papa, M. A.; Paris, H.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Pedraza, M.; Peiris, P.; Penn, S.; Perreca, A.; Phelps, M.; Pichot, M.; Pickenpack, M.; Piergiovanni, F.; Pierro, V.; Pinard, L.; Pindor, B.; Pinto, I. M.; Pitkin, M.; Poeld, J.; Poggiani, R.; Poole, V.; Poux, C.; Predoi, V.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prix, R.; Prodi, G. A.; Prokhorov, L.; Puncken, O.; Punturo, M.; Puppo, P.; Quetschke, V.; Quintero, E.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Rácz, I.; Radkins, H.; Raffai, P.; Raja, S.; Rajalakshmi, G.; Rakhmanov, M.; Ramet, C.; Rapagnani, P.; Raymond, V.; Re, V.; Reed, C. M.; Reed, T.; Regimbau, T.; Reid, S.; Reitze, D. H.; Ricci, F.; Riesen, R.; Riles, K.; Robertson, N. A.; Robinet, F.; Rocchi, A.; Roddy, S.; Rodriguez, C.; Rodruck, M.; Roever, C.; Rolland, L.; Rollins, J. G.; Romano, J. D.; Romano, R.; Romanov, G.; Romie, J. H.; Rosińska, D.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Salemi, F.; Sammut, L.; Sandberg, V.; Sanders, J.; Sannibale, V.; Santiago-Prieto, I.; Saracco, E.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Savage, R.; Schilling, R.; Schnabel, R.; Schofield, R. M. S.; Schreiber, E.; Schuette, D.; Schulz, B.; Schutz, B. F.; Schwinberg, P.; Scott, J.; Scott, S. M.; Seifert, F.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sergeev, A.; Shaddock, D.; Shah, S.; Shahriar, M. S.; Shaltev, M.; Shapiro, B.; Shawhan, P.; Shoemaker, D. H.; Sidery, T. L.; Siellez, K.; Siemens, X.; Sigg, D.; Simakov, D.; Singer, A.; Singer, L.; Sintes, A. M.; Skelton, G. R.; Slagmolen, B. J. J.; Slutsky, J.; Smith, J. R.; Smith, M. R.; Smith, R. J. E.; Smith-Lefebvre, N. D.; Soden, K.; Son, E. J.; Sorazu, B.; Souradeep, T.; Sperandio, L.; Staley, A.; Steinert, E.; Steinlechner, J.; Steinlechner, S.; Steplewski, S.; Stevens, D.; Stochino, A.; Stone, R.; Strain, K. A.; Strigin, S.; Stroeer, A. S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Susmithan, S.; Sutton, P. J.; Swinkels, B.; Szeifert, G.; Tacca, M.; Talukder, D.; Tang, L.; Tanner, D. B.; Tarabrin, S. P.; Taylor, R.; ter Braack, A. P. M.; Thirugnanasambandam, M. P.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Tiwari, V.; Tokmakov, K. V.; Tomlinson, C.; Toncelli, A.; Tonelli, M.; Torre, O.; Torres, C. V.; Torrie, C. I.; Travasso, F.; Traylor, G.; Tse, M.; Ugolini, D.; Unnikrishnan, C. S.; Vahlbruch, H.; Vajente, G.; Vallisneri, M.; van den Brand, J. F. J.; Van Den Broeck, C.; van der Putten, S.; van der Sluys, M. V.; van Heijningen, J.; van Veggel, A. A.; Vass, S.; Vasúth, M.; Vaulin, R.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Verkindt, D.; Verma, S.; Vetrano, F.; Viceré, A.; Vincent-Finley, R.; Vinet, J.-Y.; Vitale, S.; Vlcek, B.; Vo, T.; Vocca, H.; Vorvick, C.; Vousden, W. D.; Vrinceanu, D.; Vyachanin, S. P.; Wade, A.; Wade, L.; Wade, M.; Waldman, S. J.; Walker, M.; Wallace, L.; Wan, Y.; Wang, J.; Wang, M.; Wang, X.; Wanner, A.; Ward, R. L.; Was, M.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Welborn, T.; Wen, L.; Wessels, P.; West, M.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; White, D. J.; Whiting, B. F.; Wibowo, S.; Wiesner, K.; Wilkinson, C.; Williams, L.; Williams, R.; Williams, T.; Willis, J. L.; Willke, B.; Wimmer, M.; Winkelmann, L.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Worden, J.; Yablon, J.; Yakushin, I.; Yamamoto, H.; Yancey, C. C.; Yang, H.; Yeaton-Massey, D.; Yoshida, S.; Yum, H.; Yvert, M.; Zadrożny, A.; Zanolin, M.; Zendri, J.-P.; Zhang, F.; Zhang, L.; Zhao, C.; Zhu, H.; Zhu, X. J.; Zotov, N.; Zucker, M. E.; Zweizig, J.; LIGO Scientific Collaboration; Virgo Collaboration; Akerlof, C.; Baltay, C.; Bloom, J. S.; Cao, Y.; Cenko, S. B.; Ćwiek, A.; Ćwiok, M.; Dhillon, V.; Fox, D. B.; Gal-Yam, A.; Kasliwal, M. M.; Klotz, A.; Laas-Bourez, M.; Laher, R. R.; Law, N. M.; Majcher, A.; Małek, K.; Mankiewicz, L.; Nawrocki, K.; Nissanke, S.; Nugent, P. E.; Ofek, E. O.; Opiela, R.; Piotrowski, L.; Poznanski, D.; Rabinowitz, D.; Rapoport, S.; Richards, J. W.; Schmidt, B.; Siudek, M.; Sokołowski, M.; Steele, I. A.; Sullivan, M.; Żarnecki, A. F.; Zheng, W.

2014-03-01

During the Laser Interferometer Gravitational-wave Observatory and Virgo joint science runs in 2009-2010, gravitational wave (GW) data from three interferometer detectors were analyzed within minutes to select GW candidate events and infer their apparent sky positions. Target coordinates were transmitted to several telescopes for follow-up observations aimed at the detection of an associated optical transient. Images were obtained for eight such GW candidates. We present the methods used to analyze the image data as well as the transient search results. No optical transient was identified with a convincing association with any of these candidates, and none of the GW triggers showed strong evidence for being astrophysical in nature. We compare the sensitivities of these observations to several model light curves from possible sources of interest, and discuss prospects for future joint GW-optical observations of this type.

First Searches for Optical Counterparts to Gravitational-Wave Candidate Events

NASA Technical Reports Server (NTRS)

Aasi, J.; Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Accadia, T.; Acernese, F.; Adams, C.; Adams, T.;

Technology optimization techniques for multicomponent optical band-pass filter manufacturing

NASA Astrophysics Data System (ADS)

Baranov, Yuri P.; Gryaznov, Georgiy M.; Rodionov, Andrey Y.; Obrezkov, Andrey V.; Medvedev, Roman V.; Chivanov, Alexey N.

2016-04-01

Narrowband optical devices (like IR-sensing devices, celestial navigation systems, solar-blind UV-systems and many others) are one of the most fast-growing areas in optical manufacturing. However, signal strength in this type of applications is quite low and performance of devices depends on attenuation level of wavelengths out of operating range. Modern detectors (photodiodes, matrix detectors, photomultiplier tubes and others) usually do not have required selectivity or have higher sensitivity to background spectrum at worst. Manufacturing of a single component band-pass filter with high attenuation level of wavelength is resource-intensive task. Sometimes it's not possible to find solution for this problem using existing technologies. Different types of filters have technology variations of transmittance profile shape due to various production factors. At the same time there are multiple tasks with strict requirements for background spectrum attenuation in narrowband optical devices. For example, in solar-blind UV-system wavelengths above 290-300 nm must be attenuated by 180dB. In this paper techniques of multi-component optical band-pass filters assembly from multiple single elements with technology variations of transmittance profile shape for optimal signal-tonoise ratio (SNR) were proposed. Relationships between signal-to-noise ratio and different characteristics of transmittance profile shape were shown. Obtained practical results were in rather good agreement with our calculations.

A search for optical variability of type 2 quasars in SDSS stripe 82

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

Barth, Aaron J.; Carson, Daniel J.; Voevodkin, Alexey

Hundreds of Type 2 quasars have been identified in Sloan Digital Sky Survey (SDSS) data, and there is substantial evidence that they are generally galaxies with highly obscured central engines, in accord with unified models for active galactic nuclei (AGNs). A straightforward expectation of unified models is that highly obscured Type 2 AGNs should show little or no optical variability on timescales of days to years. As a test of this prediction, we have carried out a search for variability in Type 2 quasars in SDSS Stripe 82 using difference-imaging photometry. Starting with the Type 2 AGN catalogs of Zakamskamore » et al. and Reyes et al., we find evidence of significant g-band variability in 17 out of 173 objects for which light curves could be measured from the Stripe 82 data. To determine the nature of this variability, we obtained new Keck spectropolarimetry observations for seven of these variable AGNs. The Keck data show that these objects have low continuum polarizations (p ≲ 1% in most cases) and all seven have broad Hα and/or Mg II emission lines in their total (unpolarized) spectra, indicating that they should actually be classified as Type 1 AGNs. We conclude that the primary reason variability is found in the SDSS-selected Type 2 AGN samples is that these samples contain a small fraction of Type 1 AGNs as contaminants, and it is not necessary to invoke more exotic possible explanations such as a population of 'naked' or unobscured Type 2 quasars. Aside from misclassified Type 1 objects, the Type 2 quasars do not generally show detectable optical variability over the duration of the Stripe 82 survey.« less

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

Shim, Hyunjin; Im, Myungshin; Jeon, Yiseul

We present spectra of 1796 sources selected in the AKARI North Ecliptic Pole Wide Survey field, obtained with MMT/Hectospec and WIYN/Hydra, for which we measure 1645 redshifts. We complemented the generic flux-limited spectroscopic surveys at 11 {mu}m and 15 {mu}m, with additional sources selected based on the MIR and optical colors. In MMT/Hectospec observations, the redshift identification rates are {approx}80% for objects with R < 21.5 mag. On the other hand, in WIYN/Hydra observations, the redshift identification rates are {approx}80% at R magnitudes brighter than 19 mag. The observed spectra were classified through the visual inspection or from the linemore » diagnostics. We identified 1128 star-forming or absorption-line-dominated galaxies, 198 Type-1 active galactic nuclei (AGNs), 8 Type-2 AGNs, 121 Galactic stars, and 190 spectra in unknown category due to low signal-to-noise ratio. The spectra were flux-calibrated but to an accuracy of 0.1-0.18 dex for most of the targets and worse for the remainder. We derive star formation rates (SFRs) from the mid-infrared fluxes or from the optical emission lines, showing that our sample spans an SFR range of 0.1 to a few hundred M{sub Sun} yr{sup -1}. We find that the extinction inferred from the difference between the IR and optical SFR increases as the IR luminosity increases but with a large scatter.« less

A Multi-color Optical Survey of the Orion Nebula Cluster. II. The H-R Diagram

NASA Astrophysics Data System (ADS)

Da Rio, N.; Robberto, M.; Soderblom, D. R.; Panagia, N.; Hillenbrand, L. A.; Palla, F.; Stassun, K. G.

2010-10-01

We present a new analysis of the stellar population of the Orion Nebula Cluster (ONC) based on multi-band optical photometry and spectroscopy. We study the color-color diagrams in BVI, plus a narrowband filter centered at 6200 Å, finding evidence that intrinsic color scales valid for main-sequence dwarfs are incompatible with the ONC in the M spectral-type range, while a better agreement is found employing intrinsic colors derived from synthetic photometry, constraining the surface gravity value as predicted by a pre-main-sequence isochrone. We refine these model colors even further, empirically, by comparison with a selected sample of ONC stars with no accretion and no extinction. We consider the stars with known spectral types from the literature, and extend this sample with the addition of 65 newly classified stars from slit spectroscopy and 182 M-type from narrowband photometry; in this way, we isolate a sample of about 1000 stars with known spectral type. We introduce a new method to self-consistently derive the stellar reddening and the optical excess due to accretion from the location of each star in the BVI color-color diagram. This enables us to accurately determine the extinction of the ONC members, together with an estimate of their accretion luminosities. We adopt a lower distance for the Orion Nebula than previously assumed, based on recent parallax measurements. With a careful choice of also the spectral-type-temperature transformation, we produce the new Hertzsprung-Russell diagram of the ONC population, more populated than previous works. With respect to previous works, we find higher luminosity for late-type stars and a slightly lower luminosity for early types. We determine the age distribution of the population, peaking from ~2 to ~3 Myr depending on the model. We study the distribution of the members in the mass-age plane and find that taking into account selection effects due to incompleteness, removes an apparent correlation between mass and age. We derive the initial mass function for low- and intermediate-mass members of the ONC, which turns out to be model dependent and shows a turnover at M <~ 0.2 M sun.

Causes of cine image quality deterioration in cardiac catheterization laboratories.

PubMed

Levin, D C; Dunham, L R; Stueve, R

1983-10-01

Deterioration of cineangiographic image quality can result from malfunctions or technical errors at a number of points along the cine imaging chain: generator and automatic brightness control, x-ray tube, x-ray beam geometry, image intensifier, optics, cine camera, cine film, film processing, and cine projector. Such malfunctions or errors can result in loss of image contrast, loss of spatial resolution, improper control of film optical density (brightness), or some combination thereof. While the electronic and photographic technology involved is complex, physicians who perform cardiac catheterization should be conversant with the problems and what can be done to solve them. Catheterization laboratory personnel have control over a number of factors that directly affect image quality, including radiation dose rate per cine frame, kilovoltage or pulse width (depending on type of automatic brightness control), cine run time, selection of small or large focal spot, proper object-intensifier distance and beam collimation, aperture of the cine camera lens, selection of cine film, processing temperature, processing immersion time, and selection of developer.

Monitoring of Diisopropyl Fluorophosphate Hydrolysis by Fluoride-Selective Polymeric Films Using Absorbance Spectroscopy

PubMed Central

Ramanathan, Madhumati; Wang, Lin; Wild, James R.; Meyeroff, Mark E.; Simonian, Aleksandr L.

2012-01-01

In this study, a novel system for the detection and quantification of organofluorophosphonates (OFP) has been developed by using an optical sensing polymeric membrane to detect the fluoride ions produced upon OFP hydrolysis. Diisopropyl fluorophosphate (DFP), a structural analogue of Type G Chemical Warfare Agents such as Sarin (GB) and Soman (GD), is used as the surrogate target analyte. An optical sensing fluoride-ion-selective polymeric film was formulated from plasticized PVC containing aluminum(III) octaethylporphyrin and ETH 7075 chromoionophore (Al[OEP]-ETH 7075). Selected formulations were used to detect the fluoride ions produced by the catalytic hydrolysis of DFP by the enzyme organophosphate hydrolase (OPH, EC 3.1.8.1). The changes in absorbance that corresponded to the deprotonated state of chromoionophore within the film results from simultaneous co-extraction of fluoride and protons as DFP hydrolysis takes place in the solution phase in contact with the film. The developed sensing system demonstrates excellent sensitivity for concentrations as low as 0.1 µM DFP. PMID:20441875

VizieR Online Data Catalog: MIR-selected quasar parameters (Dai+, 2014)

NASA Astrophysics Data System (ADS)

Dai, Y. S.; Elvis, M.; Bergeron, J.; Fazio, G. G.; Huang, J.-S.; Wilkes, B. J.; Willmer, C. N. A.; Omont, A.; Papovich, C.

2017-03-01

The combined MIR 24 um and optical selection for this survey was designed to detect objects with luminous torus/nucleus and not biased against dusty hosts. The MIR selection allows for the detection of hot dust (a few hundred Kelvin) at the redshifts z ~ 1.5; while optical follow-up spectroscopically identified the BEL objects, confirming their unobscured (type 1) quasar nature. This MIR selection also allows for a far-infrared (FIR) cross-match to look for cool dust for SMBH-host studies, as demonstrated in Dai et al. (2012ApJ...753...33D). We select Spitzer MIPS (Rieke et al. 2004ApJS..154...25R) 24 um sources from the SWIRE survey in the ~22 deg2 LHS field centered at RA=10:46:48, DE=57:54:00 (Lonsdale et al. 2003PASP..115..897L). The SDSS imaging also covers the LHS region to r = 22.2 at 95% detection repeatability, but can go as deep as r = 23. All magnitudes are taken from the SDSS photoObj catalog in DR7, which are already corrected for Galactic extinction according to Schlegel et al. (1998ApJ...500..525S). (6 data files).

Eat-by-light fiber-optic and micro-optic devices for food quality and safety assessment

NASA Astrophysics Data System (ADS)

Mignani, A. G.; Ciaccheri, L.; Cucci, C.; Mencaglia, A. A.; Cimato, A.; Attilio, C.; Thienpont, H.; Ottevaere, H.; Paolesse, R.; Mastroianni, M.; Monti, D.; Buonocore, G.; Del Nobile, A.; Mentana, A.; Grimaldi, M. F.; Dall'Asta, C.; Faccini, A.; Galaverna, G.; Dossena, A.

2007-06-01

A selection is presented of fiber-optic and micro-optic devices that have been designed and tested for guaranteeing the quality and safety of typical foods, such as extra virgin olive oil, beer, and milk. Scattered colorimetry is used to authenticate various types of extra virgin olive oil and beer, while a fiber-optic-based device for UV-VIS-NIR absorption spectroscopy is exploited in order to obtain the hyperspectral optical signature of olive oil. This is done not only for authentication purposes, but also so as to correlate the spectral data with the content of fatty acids, which are important nutritional factors. A micro-optic sensor for the detection of olive oil aroma that is capable of distinguishing different ageing levels of extra virgin olive oil is also presented. It shows effective potential for acting as a smart cap of bottled olive oil in order to achieve a non-destructive olfactory perception of oil ageing. Lastly, a compact portable fluorometer for the rapid monitoring of the carcinogenic M1 aflatoxin in milk, is experimented.

Eat-by-light: fiber-optic and micro-optic devices for food safety and quality assessment

NASA Astrophysics Data System (ADS)

Mignani, A. G.; Ciaccheri, L.; Cucci, C.; Mencaglia, A. A.; Cimato, A.; Attilio, C.; Thienpont, H.; Ottevaere, H.; Paolesse, R.; Mastroianni, M.; Monti, D.; Buonocore, G.; Del Nobile, A.; Mentana, A.; Dall'Asta, C.; Faccini, A.; Galaverna, G.; Dossena, A.

2007-07-01

A selection of fiber-optic and micro-optic devices is presented designed and tested for monitoring the quality and safety of typical foods, namely the extra virgin olive oil, the beer, and the milk. Scattered colorimetry is used for the authentication of various types of extra virgin olive oil and beer, while a fiber-optic-based device for UV-VIS-NIR absorption spectroscopy is exploited in order to obtain the hyperspectral optical signature of olive oil. This is done not only for authentication purposes, but also so as to correlate the spectral data with the content of fatty acids that are important nutritional factors. A micro-optic sensor for the detection of olive oil aroma is presented. It is capable of distinguishing different ageing levels of extra virgin olive oil. It shows effective potential for acting as a smart cap of bottled olive oil in order to achieve a non-destructive olfactory perception of oil ageing. Lastly, a compact portable fluorometer is experimented for the rapid monitoring of the carcinogenic M1 aflatoxin in milk.

Optical multi-species gas monitoring sensor and system

NASA Technical Reports Server (NTRS)

Korman, Valentin (Inventor); Polzin, Kurt A. (Inventor)

2012-01-01

The system includes at least one light source generating light energy having a corresponding wavelength. The system's sensor is based on an optical interferometer that receives light energy from each light source. The interferometer includes a free-space optical path disposed in an environment of interest. The system's sensor includes an optical device disposed in the optical path that causes light energy of a first selected wavelength to continue traversing the optical path whereas light energy of at least one second selected wavelength is directed away from the optical path. The interferometer generates an interference between the light energy of the first selected wavelength so-traversing the optical path with the light energy at the corresponding wavelength incident on the optical interferometer. A first optical detector detects the interference. At least one second detector detects the light energy at the at least one second selected wavelength directed away from the optical path.

Perovskite-type oxide thin film integrated fiber optic sensor for high-temperature hydrogen measurement.

PubMed

Tang, Xiling; Remmel, Kurtis; Lan, Xinwei; Deng, Jiangdong; Xiao, Hai; Dong, Junhang

2009-09-15

Small size fiber optic devices integrated with chemically sensitive photonic materials are emerging as a new class of high-performance optical chemical sensor that have the potential to meet many analytical challenges in future clean energy systems and environmental management. Here, we report the integration of a proton conducting perovskite oxide thin film with a long-period fiber grating (LPFG) device for high-temperature in situ measurement of bulk hydrogen in fossil- and biomass-derived syngas. The perovskite-type Sr(Ce(0.8)Zr(0.1))Y(0.1)O(2.95) (SCZY) nanocrystalline thin film is coated on the 125 microm diameter LPFG by a facile polymeric precursor route. This fiber optic sensor (FOS) operates by monitoring the LPFG resonant wavelength (lambda(R)), which is a function of the refractive index of the perovskite oxide overcoat. At high temperature, the types and population of the ionic and electronic defects in the SCZY structure depend on the surrounding hydrogen partial pressure. Thus, varying the H(2) concentration changes the SCZY film refractive index and light absorbing characteristics that in turn shifts the lambda(R) of the LPFG. The SCZY-coated LPFG sensor has been demonstrated for bulk hydrogen measurement at 500 degrees C for its sensitivity, stability/reversibility, and H(2)-selectivity over other relevant small gases including CO, CH(4), CO(2), H(2)O, and H(2)S, etc.

Phase-selective vanadium dioxide (VO{sub 2}) nanostructured thin films by pulsed laser deposition

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

Masina, B. N., E-mail: BMasina@csir.co.za, E-mail: slafane@cdta.dz; School of Physics, University of KwaZulu-Natal, Private Bag X54001, Durban 4000; Lafane, S., E-mail: BMasina@csir.co.za, E-mail: slafane@cdta.dz

2015-10-28

Thin films of monoclinic nanostructured vanadium dioxide are notoriously difficult to produce in a selective manner. To date, post-annealing, after pulsed laser deposition (PLD), has been used to revert the crystal phase or to remove impurities, and non-glass substrates have been employed, thus reducing the efficacy of the transparency switching. Here, we overcome these limitations in PLD by optimizing a laser-ablation and deposition process through optical imaging of the laser-induced plasma. We report high quality monoclinic rutile-type vanadium dioxide (VO{sub 2}) (M1) nanoparticles without post-annealing, and on a glass substrate. Our samples demonstrate a reversible metal-to-insulator transition at ∼43 °C, withoutmore » any doping, paving the way to switchable transparency in optical materials at room temperature.« less

Selecting among competing models of electro-optic, infrared camera system range performance

USGS Publications Warehouse

Nichols, Jonathan M.; Hines, James E.; Nichols, James D.

2013-01-01

Range performance is often the key requirement around which electro-optical and infrared camera systems are designed. This work presents an objective framework for evaluating competing range performance models. Model selection based on the Akaike’s Information Criterion (AIC) is presented for the type of data collected during a typical human observer and target identification experiment. These methods are then demonstrated on observer responses to both visible and infrared imagery in which one of three maritime targets was placed at various ranges. We compare the performance of a number of different models, including those appearing previously in the literature. We conclude that our model-based approach offers substantial improvements over the traditional approach to inference, including increased precision and the ability to make predictions for some distances other than the specific set for which experimental trials were conducted.

Holographic Gratings for Optical Processing

NASA Technical Reports Server (NTRS)

Kukhtarev, Nickolai

2002-01-01

Investigation of astronomical objects and tracking of man-made space objects lead to generation of huge amount of information for optical processing. Traditional big-size optical elements (such as optical telescopes) have a tendency for increasing aperture size in order to improve sensitivity. This tendency leads to increasing of weight and costs of optical systems and stimulate search for the new, more adequate technologies. One approach to meet these demands is based on developing of holographic optical elements using new polymeric materials. We have investigated possibility to use new material PQ-PMMA (phenantrenequinone-doped PMMA (Polymethyl Methacrylate)) for fabrication of highly selective optical filters and fast spatial-temporal light modulators. This material was originally developed in Russia and later was tested in CalTech as a candidate material for optical storage. Our theoretical investigation predicts the possibility of realization of fast spatial and temporal light modulation, using volume reflection-type spectral filter. We have developed also model of holographic-grating recording in PQ-PMMA material, based on diffusional amplification. This mechanism of recording allow to receive high diffraction efficiency during recording of reflection-type volume holographic grating (holographic mirror). We also investigated recording of dynamic gratings in the photorefractive crystals LiNbO3 (LN) for space-based spectroscopy and for adaptive correction of aberrations in the telescope's mirrors. We have shown, that specific 'photogalvanic' mechanism of holographic grating recording in LN allow to realize recording of blazed gratings for volume and surface gratings. Possible applications of dynamic gratings in LN for amplification of images, transmitted through an imaging fiber guide was also demonstrated.

An Einstein Observatory SAO-based catalog of B-type stars

NASA Technical Reports Server (NTRS)

Grillo, F.; Sciortino, S.; Micela, G.; Vaiana, G. S.; Harnden, F. R., Jr.

1992-01-01

About 4000 X-ray images obtained with the Einstein Observatory are used to measure the 0.16-4.0 keV emission from 1545 B-type SAO stars falling in the about 10 percent of the sky surveyed with the IPC. Seventy-four detected X-ray sources with B-type stars are identified, and it is estimated that no more than 15 can be misidentified. Upper limits to the X-ray emission of the remaining stars are presented. In addition to summarizing the X-ray measurements and giving other relevant optical data, the present extensive catalog discusses the reduction process and analyzes selection effects associated with both SAO catalog completeness and IPC target selection procedures. It is concluded that X-ray emission, at the level of Lx not less than 10 exp 30 ergs/s, is quite common in B stars of early spectral types (B0-B3), regardless of luminosity class, but that emission, at the same level, becomes less common, or nonexistent, in later B-type stars.

Radio stars - A possible link between the Hipparcos optical reference frame and an extra-galactic very long baseline interferometry reference frame

NASA Technical Reports Server (NTRS)

Lestrade, J.-F.; Preston, R. A.; Slade, M. A.

1983-01-01

The concept of typing the Hipparcos optical and the JPL VLBI frames of reference by means of VLBI measurements of the positions and proper motions of the radio components of some bright stars is considered. The properties of the thermal and non-thermal radio-stars are discussed and 22 candidate stars are selected to achieve this tie. A description is given of the first VLBI attempt to detect these stars on the intercontinental baselines of the Deep Space Network with the Mark II recording system.

Comparative study of solar optics for paraboloidal concentrators

NASA Technical Reports Server (NTRS)

Wen, L.; Poon, P.; Carley, W.; Huang, L.

1979-01-01

Different analytical methods for computing the flux distribution on the focal plane of a paraboloidal solar concentrator are reviewed. An analytical solution in algebraic form is also derived for an idealized model. The effects resulting from using different assumptions in the definition of optical parameters used in these methodologies are compared and discussed in detail. These parameters include solar irradiance distribution (limb darkening and circumsolar), reflector surface specular spreading, surface slope error, and concentrator pointing inaccuracy. The type of computational method selected for use depends on the maturity of the design and the data available at the time the analysis is made.

Primary chromatic aberration elimination via optimization work with genetic algorithm

NASA Astrophysics Data System (ADS)

Wu, Bo-Wen; Liu, Tung-Kuan; Fang, Yi-Chin; Chou, Jyh-Horng; Tsai, Hsien-Lin; Chang, En-Hao

2008-09-01

Chromatic Aberration plays a part in modern optical systems, especially in digitalized and smart optical systems. Much effort has been devoted to eliminating specific chromatic aberration in order to match the demand for advanced digitalized optical products. Basically, the elimination of axial chromatic and lateral color aberration of an optical lens and system depends on the selection of optical glass. According to reports from glass companies all over the world, the number of various newly developed optical glasses in the market exceeds three hundred. However, due to the complexity of a practical optical system, optical designers have so far had difficulty in finding the right solution to eliminate small axial and lateral chromatic aberration except by the Damped Least Squares (DLS) method, which is limited in so far as the DLS method has not yet managed to find a better optical system configuration. In the present research, genetic algorithms are used to replace traditional DLS so as to eliminate axial and lateral chromatic, by combining the theories of geometric optics in Tessar type lenses and a technique involving Binary/Real Encoding, Multiple Dynamic Crossover and Random Gene Mutation to find a much better configuration for optical glasses. By implementing the algorithms outlined in this paper, satisfactory results can be achieved in eliminating axial and lateral color aberration.

Applications of maximally concentrating optics for solar energy collection

NASA Astrophysics Data System (ADS)

O'Gallagher, J.; Winston, R.

1985-11-01

A new family of optical concentrators based on a general nonimaging design principle for maximizing the geometric concentration, C, for radiation within a given acceptance half angle ±θα has been developed. The maximum limit exceeds by factors of 2 to 10 that attainable by systems using focusing optics. The wide acceptance angles permitted using these techniques have several unique advantages for solar concentrators including the elimination of the diurnal tracking requirement at intermediate concentrations (up to ˜10x), collection of circumsolar and some diffuse radiation, and relaxed tolerances. Because of these advantages, these types of concentrators have applications in solar energy wherever concentration is desired, e.g. for a wide variety of both thermal and photovoltaic uses. The basic principles of nonimaging optical design are reviewed. Selected configurations for thermal collector applications are discussed and the use of nonimaging elements as secondary concentrators is illustrated in the context of higher concentration applications.

Demonstration of the spin solar cell and spin photodiode effect

PubMed Central

Endres, B.; Ciorga, M.; Schmid, M.; Utz, M.; Bougeard, D.; Weiss, D.; Bayreuther, G.; Back, C.H.

2013-01-01

Spin injection and extraction are at the core of semiconductor spintronics. Electrical injection is one method of choice for the creation of a sizeable spin polarization in a semiconductor, requiring especially tailored tunnel or Schottky barriers. Alternatively, optical orientation can be used to generate spins in semiconductors with significant spin-orbit interaction, if optical selection rules are obeyed, typically by using circularly polarized light at a well-defined wavelength. Here we introduce a novel concept for spin injection/extraction that combines the principle of a solar cell with the creation of spin accumulation. We demonstrate that efficient optical spin injection can be achieved with unpolarized light by illuminating a p-n junction where the p-type region consists of a ferromagnet. The discovered mechanism opens the window for the optical generation of a sizeable spin accumulation also in semiconductors without direct band gap such as Si or Ge. PMID:23820766

Nonlinear optical effects in organic microstructures

NASA Astrophysics Data System (ADS)

Novikov, Vladimir B.; Mamonov, Evgeniy A.; Kopylov, Denis A.; Mitetelo, Nikolai V.; Venkatakrishnarao, D.; Narayana, YSLV; Chandrasekar, R.; Murzina, Tatiana V.

2017-05-01

Organic microstructures attract much attention due to their unique properties originating from the design of their shape and optical parameters. In this work we discuss the linear, second- and third-order nonlinear optical effects in arrays and in individual organic microstructures composed by self-assembling technique and formed randomly on top of a solid substrate. The structures under study consist of micro-spheres, -hemispheres or -frustums made of red laser dye and reveal an intense fluorescence (FL) in the visible spectral range. Importantly, that due to a high value of the refractive index and confined geometry, such micro-structures support the excitation of whispering gallery modes (WGM), which brings about strong and spectrally-selected light localization. We show that an amplification of the nonlinear optical effects is observed for these structures as compared to a homogeneous dye film of similar composition. The obtained data are in agreement with the results of the FDTD calculations performed for the structures of different dimensions. Perspectives of application of such type of organic nonlinear microresonators in optical devices are discussed.

Optical Properties of Aerosol Types from Satellite and Ground-based Observations

NASA Astrophysics Data System (ADS)

Lin, Tang-Huang; Liu, Gin-Rong; Liu, Chian-Yi

2014-05-01

In this study, the properties of aerosol types are characterized from the aspects of remote sensing and in situ measurements. Particles of dust, smoke and anthropogenic pollutant are selected as the principal types in the study. The measurements of AERONET sites and MODIS data, during the dust storm and biomass burning events in the period from 2002 to 2008, suggest that the aerosol species can be discriminated sufficiently based on the dissimilarity of AE (Ångström exponent) and SSA (single scattering albedo) properties. However, the physicochemical characteristics of source aerosols can be altered after the external/internal combination along the pathway of transportation, thus induce error to the satellite retrievals. In order to eliminate from this kind of errors, the optical properties of mixed aerosols (external) are also simulated with the database of dust and soot aggregates in this study. The preliminary results show that SSA value (at 470 nm) of mineral dust may decay 5-11 % when external mixed with 15-30 % soot aggregates, then result in 11-22 % variation of reflectance observed from satellite which could lead to sufficiently large uncertainty on the retrieval of aerosol optical thickness. As a result, the effect of heterogeneous mixture should be taken into account for more accurate retrieval of aerosol properties, especially after the long-range transport. Keywords: Aerosol type, Ångström exponent, Single scattering albedo, AERONET, MODIS, External mixture

Morphology and astrometry of Infrared-Faint Radio Sources

NASA Astrophysics Data System (ADS)

Middelberg, Enno; Norris, Ray; Randall, Kate; Mao, Minnie; Hales, Christopher

2008-10-01

Infrared-Faint Radio Sources, or IFRS, are an unexpected class of object discovered in the Australia Telescope Large Area Survey, ATLAS. They are compact 1.4GHz radio sources with no visible counterparts in co-located (relatively shallow) Spitzer infrared and optical images. We have detected two of these objects with VLBI, indicating the presence of an AGN. These observations and our ATLAS data indicate that IFRS are extended on scales of arcseconds, and we wish to image their morphologies to obtain clues about their nature. These observations will also help us to select optical counterparts from very deep, and hence crowded, optical images which we have proposed. With these data in hand, we will be able to compare IFRS to known object types and to apply for spectroscopy to obtain their redshifts.

Comparison of the Climates of Selected Locations in the United States with the Climate of Beersheba, Israel.

DTIC Science & Technology

1981-01-01

INTRODUCTION .. ...... . . . .. .. .. .... 1 II. THE CLIMATE OF BEERSHEBA .............. 3 A. KZ~ppen Classification. ............. 3 B. Synoptic Features...Local Mean Solar Time. ............. 18 B. Period of Observation .. ........... 20 C. Statistical Calculations. .......... 20 1. Introduction ...157 vi I. INTRODUCTION Battlefield obscuration plays an important role in the performance of Army electro-optical devices. In turn, the type

Enantio-selective optode for the β-blocker propranolol

NASA Astrophysics Data System (ADS)

He, Huarui; Uray, Georg; Wolfbeis, Otto S.

1991-03-01

We present a scheme for sensing optical isomers (enantiomers) of biogenic amines such as the Bblocker propranolol. Recognition of one of the enantiomers of propranolol is accomplished by specific interaction of the amine (which is present in the protonated ammonium form at physiological pH) with an optically active substrate (dibutyl tartrate) in a pvc membrane. As the ammonium ion is carried into the pvc membrane a proton is simultaneously released from the proton carrier (a lipophilic phenolic xanthene dye which undergoes protolytic dissociation in the pvc membrane) which thereby suffers a color change. The sensor responds to propranolol but also to other biogenic amines such as 1-phenylethylamine and norephedrine in the 20 pM to 10 mM range but has a pH-dependent response. The selectivity factors depend on the type of receptor and range from 0. 0 to 0. 30.

The Rise of SN 2014J in the Nearby Galaxy M 82

NASA Technical Reports Server (NTRS)

A.Goobar; Johansson, J.; Amanullah, R.; Cao, Y.; Perley, D.A.; Kasliwal, M. M.; Ferreti, R.; Nugent, P. E.; Harris, C.; Cenko, S. B.

2014-01-01

We report on the discovery of SN 2014J in the nearby galaxy M 82. Given its proximity, it offers the best opportunity to date to study a thermonuclear supernova over a wide range of the electromagnetic spectrum. Optical, near-IR and mid-IR observations on the rising lightcurve, orchestrated by the intermediate Palomar Transient Factory (iPTF), show that SN 2014J is a spectroscopically normal Type Ia supernova, albeit exhibiting high-velocity features in its spectrum and heavily reddened by dust in the host galaxy. Our earliest detections start just hours after the fitted time of explosion. We use high-resolution optical spectroscopy to analyze the dense intervening material and do not detect any evolution in the resolved absorption features during the lightcurve rise. Similarly to other highly reddened Type Ia supernovae, a low value of total-to-selective extinction, R (sub V) less than or approximately equal to 2, provides the best match to our observations. We also study pre-explosion optical and near-IR images from HST with special emphasis on the sources nearest to the SN location.

Head-Mounted Display Technology for Low Vision Rehabilitation and Vision Enhancement

PubMed Central

Ehrlich, Joshua R.; Ojeda, Lauro V.; Wicker, Donna; Day, Sherry; Howson, Ashley; Lakshminarayanan, Vasudevan; Moroi, Sayoko E.

2017-01-01

Purpose To describe the various types of head-mounted display technology, their optical and human factors considerations, and their potential for use in low vision rehabilitation and vision enhancement. Design Expert perspective. Methods An overview of head-mounted display technology by an interdisciplinary team of experts drawing on key literature in the field. Results Head-mounted display technologies can be classified based on their display type and optical design. See-through displays such as retinal projection devices have the greatest potential for use as low vision aids. Devices vary by their relationship to the user’s eyes, field of view, illumination, resolution, color, stereopsis, effect on head motion and user interface. These optical and human factors considerations are important when selecting head-mounted displays for specific applications and patient groups. Conclusions Head-mounted display technologies may offer advantages over conventional low vision aids. Future research should compare head-mounted displays to commonly prescribed low vision aids in order to compare their effectiveness in addressing the impairments and rehabilitation goals of diverse patient populations. PMID:28048975

Activity in X-ray-selected late-type stars

NASA Technical Reports Server (NTRS)

Takalo, Leo O.; Nousek, J. A.

1988-01-01

A spectroscopic study has been conducted of nine X-ray bright late-type stars selected from two Einstein X-ray surveys: the Columbia Astrophysical Laboratory Survey (five stars) and the CFA Medium Sensitivity Survey (MSS; four stars). Spectral classes were determined and radial and V sin(i) velocities were measured for the stars. Four of the Columbia Survey stars were found to be new RS CVn-type binaries. The fifth Columbia survey star was found to be an active G dwarf star without evidence for binarity. None of the four MSS stars were found to be either binaries or optically active stars. Activity in these stars was assessed by measuring the excess emission in H-alpha and the Ca II IRT (8498, 8542) lines in comparison with inactive stars of similar spectral types. A correlation was found between X-ray luminosity and V sin(i) and H-alpha line excess. The measured excess line emission in H-alpha was also correlated with V sin(i) but not with the IRT line excess.

Efficient Incorporation of Mg in Solution Grown GaN Crystals

NASA Astrophysics Data System (ADS)

Freitas, Jaime A., Jr.; Feigelson, Boris N.; Anderson, Travis J.

2013-11-01

Detailed spectrometry and optical spectroscopy studies carried out on GaN crystals grown in solution detect and identify Mg as the dominant shallow acceptor. Selective etching of crystals with higher Mg levels than that of the donor concentration background indicates that Mg acceptors incorporate preferentially in the N-polar face. Electrical transport measurements verified an efficient incorporation and activation of the Mg acceptors. These results suggest that this growth method has the potential to produce p-type doped epitaxial layers or p-type substrates characterized by high hole concentration and low defect density.

Measurement of the transmittance of edible films of aloe vera (barbadensis miller) and cassava starch using optical fibers trifurcated

NASA Astrophysics Data System (ADS)

Díaz, L.; Reales, J.; Torres, C.

2017-01-01

In Colombia, especially in the Atlantic Coast it is produced and marketed the costeño cheese, an indigenous product of the gastronomy of this region, but the prolonged exposure of this product to the environment leads to microbial contamination and non-enzymatic rancidity. For this reason the transmittance of an edible coating based in aloe vera gel and cassava starch to preserve costeño cheese was evaluated using trifurcated optical fibers. The results become a tool for the selection of treatments in making edible films and their subsequent use in coatings for various types of food products.

Short cavity active mode locking fiber laser for optical sensing and imaging

NASA Astrophysics Data System (ADS)

Lee, Hwi Don; Han, Ga Hee; Jeong, Syung Won; Jeong, Myung Yung; Kim, Chang-Seok; Shin, Jun Geun; Lee, Byeong Ha; Eom, Tae Joong

2014-05-01

We demonstrate a highly linear wavenumber- swept active mode locking (AML) fiber laser for optical sensing and imaging without any wavenumber-space resampling process. In this all-electric AML wavenumber-swept mechanism, a conventional wavelength selection filter is eliminated and, instead, the suitable programmed electric modulation signal is directly applied to the gain medium. Various types of wavenumber (or wavelength) tunings can be implemented because of the filter-less cavity configuration. Therefore, we successfully demonstrate a linearly wavenumber-swept AML fiber laser with 26.5 mW of output power to obtain an in-vivo OCT image at the 100 kHz swept rate.

Design, fabrication and performance of two grazing incidence telescopes for celestial extreme ultraviolet astronomy

NASA Technical Reports Server (NTRS)

Lampton, M.; Cash, W.; Malina, R. F.; Bowyer, S.

1977-01-01

The design and performance of grazing incidence telescopes for celestial extreme ultraviolet (EUV) astronomy are described. The telescopes basically consist of a star tracker, collimator, grazing incidence mirror, vacuum box lid, vacuum housing, filters, a ranicon detector, an electronics box, and an aspect camera. For the survey mirror a Wolter-Schwarzschild type II configuration was selected. Diamond-turning was used for mirror fabrication, a technique which machines surfaces to the order of 10 microns over the required dimensions. The design of the EUV spectrometer is discussed with particular reference to the optics for a primarily spectroscopic application and the fabrication of the f/10 optics.

Optical multiple access techniques for on-board routing

NASA Technical Reports Server (NTRS)

Mendez, Antonio J.; Park, Eugene; Gagliardi, Robert M.

1992-01-01

The purpose of this research contract was to design and analyze an optical multiple access system, based on Code Division Multiple Access (CDMA) techniques, for on board routing applications on a future communication satellite. The optical multiple access system was to effect the functions of a circuit switch under the control of an autonomous network controller and to serve eight (8) concurrent users at a point to point (port to port) data rate of 180 Mb/s. (At the start of this program, the bit error rate requirement (BER) was undefined, so it was treated as a design variable during the contract effort.) CDMA was selected over other multiple access techniques because it lends itself to bursty, asynchronous, concurrent communication and potentially can be implemented with off the shelf, reliable optical transceivers compatible with long term unattended operations. Temporal, temporal/spatial hybrids and single pulse per row (SPR, sometimes termed 'sonar matrices') matrix types of CDMA designs were considered. The design, analysis, and trade offs required by the statement of work selected a temporal/spatial CDMA scheme which has SPR properties as the preferred solution. This selected design can be implemented for feasibility demonstration with off the shelf components (which are identified in the bill of materials of the contract Final Report). The photonic network architecture of the selected design is based on M(8,4,4) matrix codes. The network requires eight multimode laser transmitters with laser pulses of 0.93 ns operating at 180 Mb/s and 9-13 dBm peak power, and 8 PIN diode receivers with sensitivity of -27 dBm for the 0.93 ns pulses. The wavelength is not critical, but 830 nm technology readily meets the requirements. The passive optical components of the photonic network are all multimode and off the shelf. Bit error rate (BER) computations, based on both electronic noise and intercode crosstalk, predict a raw BER of (10 exp -3) when all eight users are communicating concurrently. If better BER performance is required, then error correction codes (ECC) using near term electronic technology can be used. For example, the M(8,4,4) optical code together with Reed-Solomon (54,38,8) encoding provides a BER of better than (10 exp -11). The optical transceiver must then operate at 256 Mb/s with pulses of 0.65 ns because the 'bits' are now channel symbols.

Femtosecond laser processing of optical fibres for novel sensor development

NASA Astrophysics Data System (ADS)

Kalli, Kyriacos; Theodosiou, Antreas; Ioannou, Andreas; Lacraz, Amedee

2017-04-01

We present results of recent research where we have utilized a femtosecond laser to micro-structure silica and polymer optical fibres in order to realize versatile optical components such as diffractive optical elements on the fibre end face, the inscription of integrated waveguide circuits in the fibre cladding and novel optical fibre sensors designs based on Bragg gratings in the core. A major hurdle in tailoring or modifying the properties of optical fibres is the development of an inscription method that can prove to be a flexible and reliable process that is generally applicable to all optical fibre types; this requires careful matching of the laser parameters and optics in order to examine the spatial limits of direct laser writing, whether the application is structuring at the surface of the optical fibre or inscription in the core and cladding of the fibre. We demonstrate a variety of optical components such as two-dimensional grating structures, Bessel, Airy and vortex beam generators; moreover, optical bridging waveguides inscribed in the cladding of single-mode fibre as a means to selectively couple light from single-core to multi-core optical fibres, and demonstrate a grating based sensor; finally, we have developed a novel femtosecond laser inscription method for the precise inscription of tailored Bragg grating sensors in silica and polymer optical fibres. We also show that this novel fibre Bragg grating inscription technique can be used to modify and add versatility to an existing, encapsulated optical fibre pressure sensor.

The K-selected Butcher-Oemler Effect

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

Stanford, S A; De Propris, R; Dickinson, M

2004-03-02

We investigate the Butcher-Oemler effect using samples of galaxies brighter than observed frame K* + 1.5 in 33 clusters at 0.1 {approx}< z {approx}< 0.9. We attempt to duplicate as closely as possible the methodology of Butcher & Oemler. Apart from selecting in the K-band, the most important difference is that we use a brightness limit fixed at 1.5 magnitudes below an observed frame K* rather than the nominal limit of rest frame M(V ) = -20 used by Butcher & Oemler. For an early type galaxy at z = 0.1 our sample cutoff is 0.2 magnitudes brighter than restmore » frame M(V ) = -20, while at z = 0.9 our cutoff is 0.9 magnitudes brighter. If the blue galaxies tend to be faint, then the difference in magnitude limits should result in our measuring lower blue fractions. A more minor difference from the Butcher & Oemler methodology is that the area covered by our galaxy samples has a radius of 0.5 or 0.7 Mpc at all redshifts rather than R{sub 30}, the radius containing 30% of the cluster population. In practice our field sizes are generally similar to those used by Butcher & Oemler. We find the fraction of blue galaxies in our K-selected samples to be lower on average than that derived from several optically selected samples, and that it shows little trend with redshift. However, at the redshifts z < 0.6 where our sample overlaps with that of Butcher & Oemler, the difference in fB as determined from our K-selected samples and those of Butcher & Oemler is much reduced. The large scatter in the measured f{sub B}, even in small redshift ranges, in our study indicates that determining the f{sub B} for a much larger sample of clusters from K-selected galaxy samples is important. As a test of our methods, our data allow us to construct optically-selected samples down to rest frame M(V ) = -20, as used by Butcher & Oemler, for four clusters that are common between our sample and that of Butcher & Oemler. For these rest V selected samples, we find similar fractions of blue galaxies to Butcher & Oemler, while the K selected samples for the same 4 clusters yield blue fractions which are typically half as large. This comparison indicates that selecting in the K-band is the primary difference between our study and previous optically-based studies of the Butcher & Oemler effect. Selecting in the observed K-band is more nearly a process of selecting galaxies by their mass than is the case for optically-selected samples. Our results suggest that the Butcher-Oemler effect is at least partly due to low mass galaxies whose optical luminosities are boosted. These lower mass galaxies could evolve into the rich dwarf population observed in nearby clusters.« less

The Chandra COSMOS-Legacy Survey: Source X-Ray Spectral Properties

NASA Astrophysics Data System (ADS)

Marchesi, S.; Lanzuisi, G.; Civano, F.; Iwasawa, K.; Suh, H.; Comastri, A.; Zamorani, G.; Allevato, V.; Griffiths, R.; Miyaji, T.; Ranalli, P.; Salvato, M.; Schawinski, K.; Silverman, J.; Treister, E.; Urry, C. M.; Vignali, C.

2016-10-01

We present the X-ray spectral analysis of the 1855 extragalactic sources in the Chandra COSMOS-Legacy survey catalog having more than 30 net counts in the 0.5-7 keV band. A total of 38% of the sources are optically classified type 1 active galactic nuclei (AGNs), 60% are type 2 AGNs, and 2% are passive, low-redshift galaxies. We study the distribution of AGN photon index Γ and of the intrinsic absorption {N}{{H},{{z}}} based on the sources’ optical classification: type 1 AGNs have a slightly steeper mean photon index Γ than type 2 AGNs, which, on the other hand, have average {N}{{H},{{z}}} ˜ 3 times higher than type 1 AGNs. We find that ˜15% of type 1 AGNs have {N}{{H},{{z}}}\\gt {10}22 cm-2, I.e., are obscured according to the X-ray spectral fitting; the vast majority of these sources have {L}2{--10{keV}} \\gt 1044 erg s-1. The existence of these objects suggests that optical and X-ray obscuration can be caused by different phenomena, the X-ray obscuration being, for example, caused by dust-free material surrounding the inner part of the nuclei. Approximately 18% of type 2 AGNs have {N}{{H},{{z}}}\\lt {10}22 cm-2, and most of these sources have low X-ray luminosities (L {}2{--10{keV}} \\lt 1043 erg s-1). We expect a part of these sources to be low-accretion, unobscured AGNs lacking broad emission lines. Finally, we also find a direct proportional trend between {N}{{H},{{z}}} and host-galaxy mass and star formation rate, although part of this trend is due to a redshift selection effect.

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

Lee, Jaekwang; Huang, Jingsong; Sumpter, Bobby G.

Compared with their bulk counterparts, 2D materials can sustain much higher elastic strain at which optical quantities such as bandgaps and absorption spectra governing optoelectronic device performance can be modified with relative ease. Using first-principles density functional theory and quasiparticle GW calculations, we demonstrate how uniaxial tensile strain can be utilized to optimize the electronic and optical properties of transition metal dichalcogenide lateral (in-plane) heterostructures such as MoX 2/WX 2 (X = S, Se, Te). We find that these lateral-type heterostructures may facilitate efficient electron–hole separation for light detection/harvesting and preserve their type II characteristic up to 12% of uniaxialmore » strain. Based on the strain-dependent bandgap and band offset, we show that uniaxial tensile strain can significantly increase the power conversion efficiency of these lateral heterostructures. Our results suggest that these strain-engineered lateral heterostructures are promising for optimizing optoelectronic device performance by selectively tuning the energetics of the bandgap.« less

Glassblowers' ocular health and safety: optical radiation hazards and eye protection assessment.

PubMed

Oriowo, O M; Chou, B R; Cullen, A P

1997-05-01

The aims of this study were to investigate the levels of optical radiation exposure in glassblowing and to determine type(s) of protective eyewear commonly used. Radiometric measurements of radiant emissions from different molten glass materials and heating systems were carried out in six installations. Spectral transmittance curves of available protective lenses used at the locations were obtained. Significant variation (P = 0.0001) in ocular irradiation was obtained. All operations produced irradiances higher than the threshold limit values (TLVs) for the visible spectrum (400 to 700 nm). In craft glassblowing which employs furnace systems, irradiance levels exceeding the TLVs for near infrared (760 1o 1100 nm) were obtained. Molten soda-lime and quartz glasses emitted substantial subthreshold near UV radiation. This study shows that variation exists in glassblowing ocular radiation exposure due to different glass materials and heating systems, therefore selection of appropriate eye protector should be on an individual basis.

Self-accommodation of B19' martensite in Ti-Ni shape memory alloys - Part I. Morphological and crystallographic studies of the variant selection rule

NASA Astrophysics Data System (ADS)

Nishida, M.; Nishiura, T.; Kawano, H.; Inamura, T.

2012-06-01

The self-accommodation morphologies of B19‧ martensite in Ti-Ni alloys have been investigated by optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Twelve pairs of minimum units consisting of two habit plane variants (HPVs) with V-shaped morphology connected to a ? B19‧ type I variant accommodation twin were observed. Three types of self-accommodation morphologies, based on the V-shaped minimum unit, developed around one of the {111}B2 traces, which were triangular, rhombic and hexangular and consisted of three, four and six HPVs, respectively. In addition, the variant selection rule and the number of possible HPV combinations in each of these self-accommodation morphologies are discussed.

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.

Reference data set of volcanic ash physicochemical and optical properties

NASA Astrophysics Data System (ADS)

Vogel, A.; Diplas, S.; Durant, A. J.; Azar, A. S.; Sunding, M. F.; Rose, W. I.; Sytchkova, A.; Bonadonna, C.; Krüger, K.; Stohl, A.

2017-09-01

Uncertainty in the physicochemical and optical properties of volcanic ash particles creates errors in the detection and modeling of volcanic ash clouds and in quantification of their potential impacts. In this study, we provide a data set that describes the physicochemical and optical properties of a representative selection of volcanic ash samples from nine different volcanic eruptions covering a wide range of silica contents (50-80 wt % SiO2). We measured and calculated parameters describing the physical (size distribution, complex shape, and dense-rock equivalent mass density), chemical (bulk and surface composition), and optical (complex refractive index from ultraviolet to near-infrared wavelengths) properties of the volcanic ash and classified the samples according to their SiO2 and total alkali contents into the common igneous rock types basalt to rhyolite. We found that the mass density ranges between ρ = 2.49 and 2.98 g/cm3 for rhyolitic to basaltic ash types and that the particle shape varies with changing particle size (d < 100 μm). The complex refractive indices in the wavelength range between λ = 300 nm and 1500 nm depend systematically on the composition of the samples. The real part values vary from n = 1.38 to 1.66 depending on ash type and wavelength and the imaginary part values from k = 0.00027 to 0.00268. We place our results into the context of existing data and thus provide a comprehensive data set that can be used for future and historic eruptions, when only basic information about the magma type producing the ash is known.

Continuum radiation from active galactic nuclei: A statistical study

NASA Technical Reports Server (NTRS)

Isobe, T.; Feigelson, E. D.; Singh, K. P.; Kembhavi, A.

1986-01-01

The physics of the continuum spectrum of active galactic nuclei (AGNs) was examined using a large data set and rigorous statistical methods. A data base was constructed for 469 objects which include radio selected quasars, optically selected quasars, X-ray selected AGNs, BL Lac objects, and optically unidentified compact radio sources. Each object has measurements of its radio, optical, X-ray core continuum luminosity, though many of them are upper limits. Since many radio sources have extended components, the core component were carefully selected out from the total radio luminosity. With survival analysis statistical methods, which can treat upper limits correctly, these data can yield better statistical results than those previously obtained. A variety of statistical tests are performed, such as the comparison of the luminosity functions in different subsamples, and linear regressions of luminosities in different bands. Interpretation of the results leads to the following tentative conclusions: the main emission mechanism of optically selected quasars and X-ray selected AGNs is thermal, while that of BL Lac objects is synchrotron; radio selected quasars may have two different emission mechanisms in the X-ray band; BL Lac objects appear to be special cases of the radio selected quasars; some compact radio sources show the possibility of synchrotron self-Compton (SSC) in the optical band; and the spectral index between the optical and the X-ray bands depends on the optical luminosity.

X-ray-bright optically faint active galactic nuclei in the Subaru Hyper Suprime-Cam wide survey

NASA Astrophysics Data System (ADS)

Terashima, Yuichi; Suganuma, Makoto; Akiyama, Masayuki; Greene, Jenny E.; Kawaguchi, Toshihiro; Iwasawa, Kazushi; Nagao, Tohru; Noda, Hirofumi; Toba, Yoshiki; Ueda, Yoshihiro; Yamashita, Takuji

2018-01-01

We construct a sample of X-ray-bright optically faint active galactic nuclei by combining Subaru Hyper Suprime-Cam, XMM-Newton, and infrared source catalogs. Fifty-three X-ray sources satisfying i-band magnitude fainter than 23.5 mag and X-ray counts with the EPIC-PN detector larger than 70 are selected from 9.1 deg2, and their spectral energy distributions (SEDs) and X-ray spectra are analyzed. Forty-four objects with an X-ray to i-band flux ratio FX/Fi > 10 are classified as extreme X-ray-to-optical flux sources. Spectral energy distributions of 48 among 53 are represented by templates of type 2 AGNs or star-forming galaxies and show the optical signature of stellar emission from host galaxies in the source rest frame. Infrared/optical SEDs indicate a significant contribution of emission from dust to the infrared fluxes, and that the central AGN is dust obscured. The photometric redshifts determined from the SEDs are in the range of 0.6-2.5. The X-ray spectra are fitted by an absorbed power-law model, and the intrinsic absorption column densities are modest (best-fit log NH = 20.5-23.5 cm-2 in most cases). The absorption-corrected X-ray luminosities are in the range of 6 × 1042-2 × 1045 erg s-1. Twenty objects are classified as type 2 quasars based on X-ray luminsosity and NH. The optical faintness is explained by a combination of redshifts (mostly z > 1.0), strong dust extinction, and in part a large ratio of dust/gas.

Testing light concentrators prototypes for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Hénault, François; Petrucci, Pierre-Olivier; Jocou, Laurent; Arezki, Brahim; Magnard, Yves; Khélifi, Bruno; Manigot, Pascal; Olive, Jean-François; Jean, Pierre; Punch, Michael

2017-09-01

With more than 30 Medium-Size Telescopes (MST) located in both North and South hemispheres, the Cherenkov Telescope Array (CTA) shall be the largest cosmic gamma ray detector ever built. Each MST focal plane consists in an array of some 1800 photomultipliers equipped with their own light concentrating optics in order to maximizing the amount of Cherenkov radiation collected by the telescope and to block stray light originating from ground environment. Within the CTA Consortium, the Institut de Planétologie et d'Astrophysique de Grenoble (IPAG) is in charge of designing, subcontracting the realization to industry, and testing the MST light concentrators. Two different optical solutions were pre-selected, respectively based on CPCs (Winston cones) and non-imaging concentrating lenses. Prototypes were manufactured by different industrial companies and tested in our laboratory on a test bench specifically built for the project. After shortly describing both optical designs, this communication is essentially focused at experimental results. Each type of concentrator has been submitted to extensive performance measurements, including radiometric efficiency at different wavelengths, rejection curves, and qualitative shape error test. The final selected concentrator is the CPC, although non-imaging lenses exhibit interesting properties in terms of radiometric performance.

Hybrid optical security system using photonic crystals and MEMS devices

NASA Astrophysics Data System (ADS)

Ciosek, Jerzy; Ostrowski, Roman

2017-10-01

An important issue in security systems is that of selection of the appropriate detectors or sensors, whose sensitivity guarantees functional reliability whilst avoiding false alarms. Modern technology enables the optimization of sensor systems, tailored to specific risk factors. In optical security systems, one of the safety parameters considered is the spectral range in which the excitation signal is associated with a risk factor. Advanced safety systems should be designed taking into consideration the possible occurrence of, often multiple, complex risk factors, which can be identified individually. The hazards of concern in this work are chemical warfare agents and toxic industrial compounds present in the forms of gases and aerosols. The proposed sensor solution is a hybrid optical system consisting of a multi-spectral structure of photonic crystals associated with a MEMS (Micro Electro-Mechanical System) resonator. The crystallographic structures of carbon present in graphene rings and graphenecarbon nanotube nanocomposites have properties which make them desirable for use in detectors. The advantage of this system is a multi-spectral sensitivity at the same time as narrow-band selectivity for the identification of risk factors. It is possible to design a system optimized for detecting specified types of risk factor from very complex signals.

1700 deg C optical temperature sensor

NASA Technical Reports Server (NTRS)

Mossey, P. W.; Shaffernocker, W. M.; Mulukutla, A. R.

1986-01-01

A new gas temperature sensor was developed that shows promise of sufficient ruggedness to be useful as a gas turbine temperature sensor. The sensor is in the form of a single-crystal aluminum oxide ceramic, ground to a cone shape and given an emissive coating. A lens and an optical fiber conduct the thermally emitted light to a remote and near-infrared photodetector assembly. Being optically coupled and passive, the sensor is highly immune to all types of electrical interference. Candidate sensors were analyzed for optical sensor performance, heat transfer characteristics, stress from gas loading. This led to the selection of the conical shape as the most promising for the gas turbine environment. One uncoated and two coated sensing elements were prepared for testing. Testing was conducted to an indicated 1750 C in a propane-air flame. Comparison with the referee optical pyrometer shows an accuracy of + or - 25 C at 1700 C for this initial development. One hundred cycles from room temperature to 1700 C left the sapphire cone intact, but some loss of the platinum, 6% rhodium coating was observed. Several areas for improving the overall performance and durability are identified.

Automated sample plan selection for OPC modeling

NASA Astrophysics Data System (ADS)

Casati, Nathalie; Gabrani, Maria; Viswanathan, Ramya; Bayraktar, Zikri; Jaiswal, Om; DeMaris, David; Abdo, Amr Y.; Oberschmidt, James; Krause, Andreas

2014-03-01

It is desired to reduce the time required to produce metrology data for calibration of Optical Proximity Correction (OPC) models and also maintain or improve the quality of the data collected with regard to how well that data represents the types of patterns that occur in real circuit designs. Previous work based on clustering in geometry and/or image parameter space has shown some benefit over strictly manual or intuitive selection, but leads to arbitrary pattern exclusion or selection which may not be the best representation of the product. Forming the pattern selection as an optimization problem, which co-optimizes a number of objective functions reflecting modelers' insight and expertise, has shown to produce models with equivalent quality to the traditional plan of record (POR) set but in a less time.

Identification of dusty massive stars in star-forming dwarf irregular galaxies in the Local Group with mid-IR photometry

NASA Astrophysics Data System (ADS)

Britavskiy, N. E.; Bonanos, A. Z.; Mehner, A.; Boyer, M. L.; McQuinn, K. B. W.

2015-12-01

Context. Increasing the statistics of spectroscopically confirmed evolved massive stars in the Local Group enables the investigation of the mass loss phenomena that occur in these stars in the late stages of their evolution. Aims: We aim to complete the census of luminous mid-IR sources in star-forming dwarf irregular (dIrr) galaxies of the Local Group. To achieve this we employed mid-IR photometric selection criteria to identify evolved massive stars, such as red supergiants (RSGs) and luminous blue variables (LBVs), by using the fact that these types of stars have infrared excess due to dust. Methods: The method is based on 3.6 μm and 4.5 μm photometry from archival Spitzer Space Telescope images of nearby galaxies. We applied our criteria to four dIrr galaxies: Pegasus, Phoenix, Sextans A, and WLM, selecting 79 point sources that we observed with the VLT/FORS2 spectrograph in multi-object spectroscopy mode. Results: We identified 13 RSGs, of which 6 are new discoveries, as well as two new emission line stars, and one candidate yellow supergiant. Among the other observed objects we identified carbon stars, foreground giants, and background objects, such as a quasar and an early-type galaxy that contaminate our survey. We use the results of our spectroscopic survey to revise the mid-IR and optical selection criteria for identifying RSGs from photometric measurements. The optical selection criteria are more efficient in separating extragalactic RSGs from foreground giants than mid-IR selection criteria, but the mid-IR selection criteria are useful for identifying dusty stars in the Local Group. This work serves as a basis for further investigation of the newly discovered dusty massive stars and their host galaxies. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme IDs 090.D-0009 and 091.D-0010.Appendix A is available in electronic form at http://www.aanda.org

Predictive analysis of photodynamic therapy applied to esophagus cancer

NASA Astrophysics Data System (ADS)

Fanjul-Vélez, F.; del Campo-Gutiérrez, M.; Ortega-Quijano, N.; Arce-Diego, J. L.

2008-04-01

The use of optical techniques in medicine has revolutionized in many cases the medical praxis, providing new tools for practitioners or improving the existing ones in the fight against diseases. The application of this technology comprises mainly two branches, characterization and treatment of biological tissues. Photodynamic Therapy (PDT) provides a solution for malignant tissue destruction, by means of the inoculation of a photosensitizer and irradiation by an optical source. The key factor of the procedure is the localization of the damage to avoid collateral harmful effects. The volume of tissue destroyed depends on the type of photosensitizer inoculated, both on its reactive characteristics and its distribution inside the tissue, and also on the specific properties of the optical source, that is, the optical power, wavelength and exposition time. In this work, a model for PDT based on the one-dimensional diffusion equation, extensible to 3D, to estimate the optical distribution in tissue, and on photosensitizer parameters to take into account the photobleaching effect is proposed. The application to esophagus cancer allows the selection of the right optical source parameters, like irradiance, wavelength or exposition time, in order to predict the area of tissue destruction.

Initial experiments to understand the interaction of stellar radiation with molecular clouds

NASA Astrophysics Data System (ADS)

Vandervort, Robert; Davis, Josh; Trantham, Matt; Klein, Sallee; Shvarts, Dov; Keiter, Paul; Drake, R. Paul

2017-10-01

Enhanced star formation triggered by local O and B type stars is an astrophysical problem of interest. O and B type stars are massive, hot stars that emit an enormous amount of radiation. This radiation acts to either compress or blow apart gas clumps in the interstellar media. For example, in the optically thick limit, when the radiation in the gas clump has a short mean free path, radiation is absorbed near the clump edge and compresses the clump. In the optically thin limit, when the mean free path is long, the radiation is absorbed throughout, acting to heat the clump. This heating explodes the gas clump. Careful selection of parameters, such as foam density or source temperature, allow the experimental platform to access different hydrodynamic regimes. 2D CRASH simulations guide our parameter selection. A stellar radiation source is mimicked by a laser-irradiated, thin, gold foil, providing a source of thermal x-rays around 100 eV. The gas clump is mimicked by low-density CRF foam. We plan to show the preliminary experimental results of this platform in the optically thick limit, from experiments scheduled in August. This work is funded by the U.S. DOE, through the NNSA-DS and SC-OFES Joint Program in HEDPLP, Grant No. DE-NA0002956, and the NLUF Program, Grant No. DE-NA0002719, and through LLE, University of Rochester by the NNSA/OICF under Cooperative Agreement No. DE-NA0001944. This work is funded by the Lawrence Livermore National Laboratory under subcontract B614207.

Highly sensitive wide bandwidth photodetector based on internal photoemission in CVD grown p-type MoS2/graphene Schottky junction.

PubMed

Vabbina, PhaniKiran; Choudhary, Nitin; Chowdhury, Al-Amin; Sinha, Raju; Karabiyik, Mustafa; Das, Santanu; Choi, Wonbong; Pala, Nezih

2015-07-22

Two dimensional (2D) Molybdenum disulfide (MoS2) has evolved as a promising material for next generation optoelectronic devices owing to its unique electrical and optical properties, such as band gap modulation, high optical absorption, and increased luminescence quantum yield. The 2D MoS2 photodetectors reported in the literature have presented low responsivity compared to silicon based photodetectors. In this study, we assembled atomically thin p-type MoS2 with graphene to form a MoS2/graphene Schottky photodetector where photo generated holes travel from graphene to MoS2 over the Schottky barrier under illumination. We found that the p-type MoS2 forms a Schottky junction with graphene with a barrier height of 139 meV, which results in high photocurrent and wide spectral range of detection with wavelength selectivity. The fabricated photodetector showed excellent photosensitivity with a maximum photo responsivity of 1.26 AW(-1) and a noise equivalent power of 7.8 × 10(-12) W/√Hz at 1440 nm.

A multiwavelength study of young stars in the Elephant Trunk

NASA Astrophysics Data System (ADS)

López Martí, B.; Bayo, A.; Morales Calderón, M.; Barrado, D.

2013-05-01

We present the results of a multiwavelength study of young stars in IC 1396A, ``the Elephant Trunk Nebula''. Our targets are selected combining optical, near-infrared and mid-infrared photometry. Near-infrared and optical spectroscopy are used to confirm their youth and to derive spectral types for these objects, showing that they are early to mid-M stars, and that our sample includes some of the lowest-mass objects reported so far in the region. The photometric and spectroscopic information is used to construct the spectral energy distributions and to study the properties of the stars (mass, age, accretion, disks, spatial location). The implications for the triggered star formation picture are discussed.

Silver nanocube aggregation gradient materials in search for total internal reflection with high phase sensitivity

NASA Astrophysics Data System (ADS)

König, Tobias A. F.; Ledin, Petr A.; Russell, Michael; Geldmeier, Jeffrey A.; Mahmoud, Mahmoud. A.; El-Sayed, Mostafa A.; Tsukruk, Vladimir V.

2015-03-01

We fabricated monolayer coatings of a silver nanocube aggregation to create a step-wise optical strip by applying different surface pressures during slow Langmuir-Blodgett deposition. The varying amount of randomly distributed nanocube aggregates with different surface coverages in gradient manner due to changes in surface pressure allows for continuous control of the polarization sensitive absorption of the incoming light over a broad optical spectrum. Optical characterization under total internal reflection conditions combined with electromagnetic simulations reveal that the broadband light absorption depends on the relative orientation of the nanoparticles to the polarization of the incoming light. By using computer simulations, we found that the electric field vector of the s-polarized light interacts with the different types of silver nanocube aggregations to excite different plasmonic resonances. The s-polarization shows dramatic changes of the plasmonic resonances at different angles of incidence (shift of 64 nm per 10° angle of incidence). With a low surface nanocube coverage (from 5% to 20%), we observed a polarization-selective high absorption of 80% (with an average 75%) of the incoming light over a broad optical range in the visible region from 400 nm to 700 nm. This large-area gradient material with location-dependent optical properties can be of particular interest for broadband light absorption, phase-sensitive sensors, and imaging.We fabricated monolayer coatings of a silver nanocube aggregation to create a step-wise optical strip by applying different surface pressures during slow Langmuir-Blodgett deposition. The varying amount of randomly distributed nanocube aggregates with different surface coverages in gradient manner due to changes in surface pressure allows for continuous control of the polarization sensitive absorption of the incoming light over a broad optical spectrum. Optical characterization under total internal reflection conditions combined with electromagnetic simulations reveal that the broadband light absorption depends on the relative orientation of the nanoparticles to the polarization of the incoming light. By using computer simulations, we found that the electric field vector of the s-polarized light interacts with the different types of silver nanocube aggregations to excite different plasmonic resonances. The s-polarization shows dramatic changes of the plasmonic resonances at different angles of incidence (shift of 64 nm per 10° angle of incidence). With a low surface nanocube coverage (from 5% to 20%), we observed a polarization-selective high absorption of 80% (with an average 75%) of the incoming light over a broad optical range in the visible region from 400 nm to 700 nm. This large-area gradient material with location-dependent optical properties can be of particular interest for broadband light absorption, phase-sensitive sensors, and imaging. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr06430e

The BAT AGN Spectroscopic Survey (BASS)

NASA Astrophysics Data System (ADS)

Koss, Michael

2017-08-01

We present the Swift BAT AGN Spectroscopic Survey (BASS) and discus the first four papers. The catalog represents an unprecedented census of hard-X-ray selected AGN in the local universe, with ~90% of sources at z<0.2. Starting from an all-sky catalog of AGN detected based on their 14-195 keV flux from the 70-month Swift/BAT catalog, we analyze a total of 1279 optical spectra, taken from twelve different telescopes, for a total of 642 spectra of unique AGN. We present the absorption and emission line measurements as well as black hole masses and accretion rates for the majority of obscured and un-obscured AGN (473), representing more than a factor of 10 increase from past studies. Consistent with previous surveys, we find an increase in the fraction of un-obscured (type 1) AGN, as measured from broad Hbeta and Halpha, with increasing 14-195 keV and 2-10 keV luminosity. We find the FWHM of the emission lines to show broad agreement with the X-ray obscuration measurements. Compared to narrow line AGN in the SDSS, the X-ray selected AGN in our sample with emission lines have a larger fraction of dustier galaxies suggesting these types of galaxies are missed in optical AGN surveys using emission line diagnostics.

Erratum: "Space Density of Optically Selected Type 2 Quasars" (2008, AJ, 136, 2373)

NASA Astrophysics Data System (ADS)

Reyes, Reinabelle; Zakamska, Nadia L.; Strauss, Michael A.; Green, Joshua; Krolik, Julian H.; Shen, Yue; Richards, Gordon T.; Anderson, Scott F.; Schneider, Donald P.

2010-03-01

Figure 12 of the paper "Space Density of Optically Selected Type 2 Quasars" compares the obscured quasar fractions derived in our work with those of other studies. Unfortunately, some of the points from these other studies were shown incorrectly. Specifically, the results from X-ray data—Hasinger (2004; open circles) and Ueda et al. (2003; open squares)—which we had taken from Figure 16 of Hopkins et al. (2006), were affected by a luminosity conversion error, in the sense that the displayed luminosities for these data were too high by ~1 dex. With this erratum, we correct this problem and update the figure. The new version (Figure 12) shows more recent results from Hasinger (2008), in lieu of the Hasinger (2004) data points. These are based on data in the redshift range z = 0.2-3.2 (open circles) in that work. The best linear fit to these data (black dashed line) is consistent with that derived for the redshift slice z = 0.4-0.8, which overlaps with the highest redshift bin in our study, and is higher than that derived for redshifts smaller than 0.4 (corresponding to a shift of ~0.7 dex in luminosity). Figure 12 also shows estimates of the obscured quasar fraction derived from the ratio of IR to bolometric luminosities of an AGN sample at redshift z ~ 1 (Treister et al. 2008; filled triangles). Because the obscured quasar fractions derived from our analysis (colored arrows) are strict lower limits, there was already a hint in the previous version of Figure 12 that at high quasar luminosities, we find higher obscured quasar fractions than X-ray surveys. The correction and updates of Figure 12 strengthen this conclusion. At face value, our derived obscured quasar fractions are consistent with those from IR data (Treister et al. 2008; filled triangles). However, we find that they are significantly higher than those derived from X-ray surveys at L_[O\\,\\mathsc {iii]}\\gtrsim 10^{9.5}\\;L_{\\odot }, especially those from the recent analysis by Hasinger (2008). This comparison strongly suggests that optical selection successfully identifies a population of luminous obscured quasars that are missed by X-ray selection.

Fiber optic crossbar switch for automatically patching optical signals

NASA Technical Reports Server (NTRS)

Bell, C. H. (Inventor)

1983-01-01

A system for automatically optically switching fiber optic data signals between a plurality of input optical fibers and selective ones of a plurality of output fibers is described. The system includes optical detectors which are connected to each of the input fibers for converting the optic data signals appearing at the respective input fibers to an RF signal. A plurality of RF to optical signal converters are arranged in rows and columns. The output of each of the optical detectors are each applied to a respective row of optical signal converted for being converters back to an optical signal when the particular optical signal converter is selectively activated by a dc voltage.

Optical properties of the uropygial gland secretion: no evidence for UV cosmetics in birds

NASA Astrophysics Data System (ADS)

Delhey, Kaspar; Peters, Anne; Biedermann, Peter H. W.; Kempenaers, Bart

2008-10-01

Ultraviolet (UV) reflectance of the plumage is common in birds and plays an important role in sexual signalling. Recently, it has been proposed that birds are able to modify plumage UV reflectance by the application of uropygial gland secretion. Based on a survey of the optical properties of this secretion from 51 species belonging to 12 avian orders, we show that two main types of uropygial secretions exist, one predominantly found in passerines and one in non-passerines, both reducing relative UV reflectance of a white background (Teflon™ tape). We quantified how each type of secretion (exemplified by blue tit and mallard) affected feather UV reflectance. Both secretions reduced overall brightness and relative UV reflectance of white mallard feathers but hardly affected the reflectance of UV/blue blue tit crown feathers. According to models of avian colour vision, changes in reflectance due to application of the secretion were at or below the discrimination threshold of most birds. We conclude that the uropygial secretion is unlikely to play a major role in modifying plumage UV reflectance. However, the optical properties of the uropygial secretion may have been selected to interfere as little as possible with visual signaling through plumage reflectance.

Holographic Optical Elements Recorded in Silver Halide Sensitized Gelatin Emulsions. Part 2. Reflection Holographic Optical Elements

NASA Astrophysics Data System (ADS)

Kim, Jong Man; Choi, Byung So; Choi, Yoon Sun; Kim, Jong Min; Bjelkhagen, Hans I.; Phillips, Nicholas J.

2002-03-01

Silver halide sensitized gelatin (SHSG) holograms are similar to holograms recorded in dichromated gelatin (DCG), the main recording material for holographic optical elements (HOEs). The drawback of DCG is its low energetic sensitivity and limited spectral response. Silver halide materials can be processed in such a way that the final hologram will have properties like a DCG hologram. Recently this technique has become more interesting since the introduction of new ultra-fine-grain silver halide (AgHal) emulsions. In particular, high spatial-frequency fringes associated with HOEs of the reflection type are difficult to construct when SHSG processing methods are employed. Therefore an optimized processing technique for reflection HOEs recorded in the new AgHal materials is introduced. Diffraction efficiencies over 90% can be obtained repeatably for reflection diffraction gratings. Understanding the importance of a selective hardening process has made it possible to obtain results similar to conventional DCG processing. The main advantage of the SHSG process is that high-sensitivity recording can be performed with laser wavelengths anywhere within the visible spectrum. This simplifies the manufacturing of high-quality, large-format HOEs, also including high-quality display holograms of the reflection type in both monochrome and full color.

A reflective-type, quasi-optical metasurface filter

NASA Astrophysics Data System (ADS)

Sima, Boyu; Momeni Hasan Abadi, Seyed Mohamad Amin; Behdad, Nader

2017-08-01

We introduce a new technique for designing quasi-optical, reflective-type spatial filters. The proposed filter is a reflective metasurface with a one dimensional, frequency-dependent phase gradient along the aperture. By careful design of each unit cell of the metasurface, the phase shift gradient provided by the adjacent unit cells can be engineered to steer the beam towards a desired, anomalous reflection direction over the passband region of the filter. Outside of that range, the phase shift gradient required to produce the anomalous reflection is not present and hence, the wave is reflected towards the specular reflection direction. This way, the metasurface acts as a reflective filter in a quasi-optical system where the detector is placed along the direction of anomalous reflection. The spectral selectivity of this filter is determined by the frequency dispersion of the metasurface's phase response. Based on this principle, a prototype of the proposed metasurface filter, which operates at 10 GHz and has a bandwidth of 3%, is designed. The device is modeled using a combination of theoretical analysis using the phased-array theory and full-wave electromagnetic simulations. A prototype of this device is also fabricated and characterized using a free-space measurement system. Experimental results agree well with the simulations.

Deep brain optical measurements of cell type-specific neural activity in behaving mice.

PubMed

Cui, Guohong; Jun, Sang Beom; Jin, Xin; Luo, Guoxiang; Pham, Michael D; Lovinger, David M; Vogel, Steven S; Costa, Rui M

2014-01-01

Recent advances in genetically encoded fluorescent sensors enable the monitoring of cellular events from genetically defined groups of neurons in vivo. In this protocol, we describe how to use a time-correlated single-photon counting (TCSPC)-based fiber optics system to measure the intensity, emission spectra and lifetime of fluorescent biosensors expressed in deep brain structures in freely moving mice. When combined with Cre-dependent selective expression of genetically encoded Ca(2+) indicators (GECIs), this system can be used to measure the average neural activity from a specific population of cells in mice performing complex behavioral tasks. As an example, we used viral expression of GCaMPs in striatal projection neurons (SPNs) and recorded the fluorescence changes associated with calcium spikes from mice performing a lever-pressing operant task. The whole procedure, consisting of virus injection, behavior training and optical recording, takes 3-4 weeks to complete. With minor adaptations, this protocol can also be applied to recording cellular events from other cell types in deep brain regions, such as dopaminergic neurons in the ventral tegmental area. The simultaneously recorded fluorescence signals and behavior events can be used to explore the relationship between the neural activity of specific brain circuits and behavior.

VizieR Online Data Catalog: Variability-selected AGN in Chandra DFS (Trevese+, 2008)

NASA Astrophysics Data System (ADS)

Trevese, D.; Boutsia, K.; Vagnetti, F.; Cappellaro, E.; Puccetti, S.

2008-11-01

Variability is a property shared by virtually all active galactic nuclei (AGNs), and was adopted as a criterion for their selection using data from multi epoch surveys. Low Luminosity AGNs (LLAGNs) are contaminated by the light of their host galaxies, and cannot therefore be detected by the usual colour techniques. For this reason, their evolution in cosmic time is poorly known. Consistency with the evolution derived from X-ray detected samples has not been clearly established so far, also because the low luminosity population consists of a mixture of different object types. LLAGNs can be detected by the nuclear optical variability of extended objects. Several variability surveys have been, or are being, conducted for the detection of supernovae (SNe). We propose to re-analyse these SNe data using a variability criterion optimised for AGN detection, to select a new AGN sample and study its properties. We analysed images acquired with the wide field imager at the 2.2m ESO/MPI telescope, in the framework of the STRESS supernova survey. We selected the AXAF field centred on the Chandra Deep Field South where, besides the deep X-ray survey, various optical data exist, originating in the EIS and COMBO-17 photometric surveys and the spectroscopic database of GOODS. (1 data file).

BAT AGN Spectroscopic Survey. VIII. Type 1 AGN with Massive Absorbing Columns

NASA Astrophysics Data System (ADS)

Shimizu, T. Taro; Davies, Richard I.; Koss, Michael; Ricci, Claudio; Lamperti, Isabella; Oh, Kyuseok; Schawinski, Kevin; Trakhtenbrot, Benny; Burtscher, Leonard; Genzel, Reinhard; Lin, Ming-yi; Lutz, Dieter; Rosario, David; Sturm, Eckhard; Tacconi, Linda

2018-04-01

We explore the relationship between X-ray absorption and optical obscuration within the BAT AGN Spectroscopic Survey (BASS), which has been collecting and analyzing the optical and X-ray spectra for 641 hard X-ray selected (E > 14 keV) active galactic nuclei (AGNs). We use the deviation from a linear broad Hα-to-X-ray relationship as an estimate of the maximum optical obscuration toward the broad line region (BLR) and compare the A V to the hydrogen column densities ({N}{{H}}) found through systematic modeling of their X-ray spectra. We find that the inferred columns implied by A V toward the BLR are often orders of magnitude less than the columns measured toward the X-ray emitting region, indicating a small-scale origin for the X-ray absorbing gas. After removing 30% of Sy 1.9s that potentially have been misclassified due to outflows, we find that 86% (164/190) of the Type 1 population (Sy 1–1.9) are X-ray unabsorbed as expected based on a single obscuring structure. However, 14% (26/190), of which 70% (18/26) are classified as Sy 1.9, are X-ray absorbed, suggesting that the BLR itself is providing extra obscuration toward the X-ray corona. The fraction of X-ray absorbed Type 1 AGNs remains relatively constant with AGN luminosity and Eddington ratio, indicating a stable BLR covering fraction.

Investigating the Impact of Optical Selection Effects on Observed Rest-frame Prompt GRB Properties

NASA Astrophysics Data System (ADS)

Turpin, D.; Heussaff, V.; Dezalay, J.-P.; Atteia, J.-L.; Klotz, A.; Dornic, D.

2016-11-01

Measuring gamma-ray burst (GRB) properties in their rest frame is crucial for understanding the physics at work in GRBs. This can only be done for GRBs with known redshifts. Since redshifts are usually measured from the optical spectrum of the afterglow, correlations between prompt and afterglow emissions may introduce biases into the distribution of the rest-frame properties of the prompt emission, especially considering that we measure the redshift of only one-third of Swift GRBs. In this paper, we study the optical flux of GRB afterglows and its connection to various intrinsic properties of GRBs. We also discuss the impact of the optical selection effect on the distribution of rest-frame prompt properties of GRBs. Our analysis is based on a sample of 90 GRBs with good optical follow-up and well-measured prompt emission. Seventy-six of them have a measure of redshift and 14 have no redshift. We compare the rest-frame prompt properties of GRBs with different afterglow optical fluxes in order to check for possible correlations between the promt properties and the optical flux of the afterglow. The optical flux is measured two hours after the trigger, which is a typical time for the measure of the redshift. We find that the optical flux of GRB afterglows in our sample is mainly driven by their optical luminosity and depends only slightly on their redshift. We show that GRBs with low and high afterglow optical fluxes have similar E {}{{pi}}, E {}{{iso}}, and L {}{{iso}}, indicating that the rest-frame distributions computed from GRBs with a redshift are not significantly distorted by optical selection effects. However, we found that the {T}90{rest} distribution is not immune to optical selection effects, which favor the selection of GRBs with longer durations. Finally, we note that GRBs well above the E {}{{pi}}-E {}{{iso}} relation have lower optical fluxes and we show that optical selection effects favor the detection of GRBs with bright optical afterglows located close to or below the best-fit E {}{{pi}}-E {}{{iso}} relation (Amati relation), whose redshift is easily measurable. With more than 300 GRBs with a redshift, we now have a much better view of the intrinsic properties of these remarkable events. At the same time, increasing statistics allow us to understand the biases acting on the measurements. The optical selection effects induced by the redshift measurement strategies cannot be neglected when we study the properties of GRBs in their rest frame, even for studies focused on prompt emission.

Adaptive Optics Image Restoration Based on Frame Selection and Multi-frame Blind Deconvolution

NASA Astrophysics Data System (ADS)

Tian, Yu; Rao, Chang-hui; Wei, Kai

Restricted by the observational condition and the hardware, adaptive optics can only make a partial correction of the optical images blurred by atmospheric turbulence. A postprocessing method based on frame selection and multi-frame blind deconvolution is proposed for the restoration of high-resolution adaptive optics images. By frame selection we mean we first make a selection of the degraded (blurred) images for participation in the iterative blind deconvolution calculation, with no need of any a priori knowledge, and with only a positivity constraint. This method has been applied to the restoration of some stellar images observed by the 61-element adaptive optics system installed on the Yunnan Observatory 1.2m telescope. The experimental results indicate that this method can effectively compensate for the residual errors of the adaptive optics system on the image, and the restored image can reach the diffraction-limited quality.

Spin and wavelength multiplexed nonlinear metasurface holography

NASA Astrophysics Data System (ADS)

Ye, Weimin; Zeuner, Franziska; Li, Xin; Reineke, Bernhard; He, Shan; Qiu, Cheng-Wei; Liu, Juan; Wang, Yongtian; Zhang, Shuang; Zentgraf, Thomas

2016-06-01

Metasurfaces, as the ultrathin version of metamaterials, have caught growing attention due to their superior capability in controlling the phase, amplitude and polarization states of light. Among various types of metasurfaces, geometric metasurface that encodes a geometric or Pancharatnam-Berry phase into the orientation angle of the constituent meta-atoms has shown great potential in controlling light in both linear and nonlinear optical regimes. The robust and dispersionless nature of the geometric phase simplifies the wave manipulation tremendously. Benefitting from the continuous phase control, metasurface holography has exhibited advantages over conventional depth controlled holography with discretized phase levels. Here we report on spin and wavelength multiplexed nonlinear metasurface holography, which allows construction of multiple target holographic images carried independently by the fundamental and harmonic generation waves of different spins. The nonlinear holograms provide independent, nondispersive and crosstalk-free post-selective channels for holographic multiplexing and multidimensional optical data storages, anti-counterfeiting, and optical encryption.

Spin and wavelength multiplexed nonlinear metasurface holography

PubMed Central

Ye, Weimin; Zeuner, Franziska; Li, Xin; Reineke, Bernhard; He, Shan; Qiu, Cheng-Wei; Liu, Juan; Wang, Yongtian; Zhang, Shuang; Zentgraf, Thomas

2016-01-01

Metasurfaces, as the ultrathin version of metamaterials, have caught growing attention due to their superior capability in controlling the phase, amplitude and polarization states of light. Among various types of metasurfaces, geometric metasurface that encodes a geometric or Pancharatnam–Berry phase into the orientation angle of the constituent meta-atoms has shown great potential in controlling light in both linear and nonlinear optical regimes. The robust and dispersionless nature of the geometric phase simplifies the wave manipulation tremendously. Benefitting from the continuous phase control, metasurface holography has exhibited advantages over conventional depth controlled holography with discretized phase levels. Here we report on spin and wavelength multiplexed nonlinear metasurface holography, which allows construction of multiple target holographic images carried independently by the fundamental and harmonic generation waves of different spins. The nonlinear holograms provide independent, nondispersive and crosstalk-free post-selective channels for holographic multiplexing and multidimensional optical data storages, anti-counterfeiting, and optical encryption. PMID:27306147

Tuning the nonlinear response of (6,5)-enriched single-wall carbon nanotubes dispersions

NASA Astrophysics Data System (ADS)

Aréstegui, O. S.; Silva, E. C. O.; Baggio, A. L.; Gontijo, R. N.; Hickmann, J. M.; Fantini, C.; Alencar, M. A. R. C.; Fonseca, E. J. S.

2017-04-01

Ultrafast nonlinear optical properties of (6,5)-enriched single-wall carbon nanotubes (SWCNTs) dispersions are investigated using the thermally managed Z-scan technique. As the (6,5) SWCNTs presented a strong resonance in the range of 895-1048 nm, the nonlinear refractive index (n2) and the absorption coefficients (β) measurements were performed tuning the laser exactly around absorption peak of the (6,5) SWCNTs. It is observed that the nonlinear response is very sensitive to the wavelength and the spectral behavior of n2 is strongly correlated to the tubes one-photon absorption band, presenting also a peak when the laser photon energy is near the tube resonance energy. This result suggests that a suitable selection of nanotubes types may provide optimized nonlinear optical responses in distinct regions of the electromagnetic spectrum. Analysis of the figures of merit indicated that this material is promising for ultrafast nonlinear optical applications under near infrared excitation.

Design of time-pulse coded optoelectronic neuronal elements for nonlinear transformation and integration

NASA Astrophysics Data System (ADS)

Krasilenko, Vladimir G.; Nikolsky, Alexander I.; Lazarev, Alexander A.; Lazareva, Maria V.

2008-03-01

In the paper the actuality of neurophysiologically motivated neuron arrays with flexibly programmable functions and operations with possibility to select required accuracy and type of nonlinear transformation and learning are shown. We consider neurons design and simulation results of multichannel spatio-time algebraic accumulation - integration of optical signals. Advantages for nonlinear transformation and summation - integration are shown. The offered circuits are simple and can have intellectual properties such as learning and adaptation. The integrator-neuron is based on CMOS current mirrors and comparators. The performance: consumable power - 100...500 μW, signal period- 0.1...1ms, input optical signals power - 0.2...20 μW time delays - less 1μs, the number of optical signals - 2...10, integration time - 10...100 of signal periods, accuracy or integration error - about 1%. Various modifications of the neuron-integrators with improved performance and for different applications are considered in the paper.

In-situ identification of meat from different animal species by shifted excitation Raman difference spectroscopy

NASA Astrophysics Data System (ADS)

Sowoidnich, Kay; Kronfeldt, Heinz-Detlef

2012-05-01

The identification of food products and the detection of adulteration are of global interest for food safety and quality control. We present a non-invasive in-situ approach for the differentiation of meat from selected animal species using microsystem diode laser based shifted excitation Raman difference spectroscopy (SERDS) at 671 nm and 785 nm. In that way, the fingerprint Raman spectra can be used for identification without a disturbing fluorescence background masking Raman signals often occurring in the investigation of biological samples. Two miniaturized SERDS measurement heads including the diode laser and all optical elements are fiber-optically coupled to compact laboratory spectrometers. To realize two slightly shifted excitation wavelengths necessary for SERDS the 671 nm laser (spectral shift: 0.7 nm, optical power: 50 mW) comprises two separate laser cavities each with a volume Bragg grating for frequency selection whereas the 785 nm light source (spectral shift: 0.5 nm, optical power: 110 mW) is a distributed feedback laser. For our investigations we chose the most consumed meat types in the US and Europe, i.e. chicken and turkey as white meat as well as pork and beef as red meat species. The applied optical powers were sufficient to detect meat Raman spectra with integration times of 10 seconds pointing out the ability for a rapid discrimination of meat samples. Principal components analysis was applied to the SERDS spectra to reveal spectral differences between the animals suitable for their identification. The results will be discussed with respect to specific characteristics of the analyzed meat species.

Optical and radio properties of X-ray selected BL Lacertae objects

NASA Technical Reports Server (NTRS)

Stocke, J. T.; Liebert, J.; Schmidt, G.; Gioia, I. M.; Maccacaro, T.

1985-01-01

The eight BL Lac objects from the HEAO 1 A-2 all-sky survey and from the Einstein medium-sensitivity survey (MSS) form a flux-limited complete X-ray selected sample. The optical and radio properties of the MSS BL Lac objects are presented and compared with those of the HEAO 1 A-2 sample and with those of radio-selected BL Lac objects. The X-ray selected BL Lac objects possess smaller polarized fractions and less violent optical variability than radio-selected BL Lac objects. These properties are consistent with the substantial starlight fraction seen in the optical spectra of a majority of these objects. This starlight allows a determination of definite redshifts for two of four MSS BL Lac objects and a probable redshift for a third. These redshifts are 0.2, 0.3, and 0.6. Despite the differences in characteristics between the X-ray selected and radio-selected samples, it is concluded that these eight objects possess most of the basic qualities of BL Lac objects and should be considered members of that class. Moreover, as a class, these X-ray selected objects have the largest ratio of X-ray to optical flux of any active galactic nuclei yet discovered.

Bolometric-Effect-Based Wavelength-Selective Photodetectors Using Sorted Single Chirality Carbon Nanotubes

PubMed Central

Zhang, Suoming; Cai, Le; Wang, Tongyu; Shi, Rongmei; Miao, Jinshui; Wei, Li; Chen, Yuan; Sepúlveda, Nelson; Wang, Chuan

2015-01-01

This paper exploits the chirality-dependent optical properties of single-wall carbon nanotubes for applications in wavelength-selective photodetectors. We demonstrate that thin-film transistors made with networks of carbon nanotubes work effectively as light sensors under laser illumination. Such photoresponse was attributed to photothermal effect instead of photogenerated carriers and the conclusion is further supported by temperature measurements. Additionally, by using different types of carbon nanotubes, including a single chirality (9,8) nanotube, the devices exhibit wavelength-selective response, which coincides well with the absorption spectra of the corresponding carbon nanotubes. This is one of the first reports of controllable and wavelength-selective bolometric photoresponse in macroscale assemblies of chirality-sorted carbon nanotubes. The results presented here provide a viable route for achieving bolometric-effect-based photodetectors with programmable response spanning from visible to near-infrared by using carbon nanotubes with pre-selected chiralities. PMID:26643777

Optical Addressing of Multi-Colour Photochromic Material Mixture for Volumetric Display.

PubMed

Hirayama, Ryuji; Shiraki, Atsushi; Naruse, Makoto; Nakamura, Shinichiro; Nakayama, Hirotaka; Kakue, Takashi; Shimobaba, Tomoyoshi; Ito, Tomoyoshi

2016-08-16

This is the first study to demonstrate that colour transformations in the volume of a photochromic material (PM) are induced at the intersections of two control light channels, one controlling PM colouration and the other controlling decolouration. Thus, PM colouration is induced by position selectivity, and therefore, a dynamic volumetric display may be realised using these two control lights. Moreover, a mixture of multiple PM types with different absorption properties exhibits different colours depending on the control light spectrum. Particularly, the spectrum management of the control light allows colour-selective colouration besides position selectivity. Therefore, a PM-based, full-colour volumetric display is realised. We experimentally construct a mixture of two PM types and validate the operating principles of such a volumetric display system. Our system is constructed simply by mixing multiple PM types; therefore, the display hardware structure is extremely simple, and the minimum size of a volume element can be as small as the size of a molecule. Volumetric displays can provide natural three-dimensional (3D) perception; therefore, the potential uses of our system include high-definition 3D visualisation for medical applications, architectural design, human-computer interactions, advertising, and entertainment.

Optical Addressing of Multi-Colour Photochromic Material Mixture for Volumetric Display

NASA Astrophysics Data System (ADS)

Hirayama, Ryuji; Shiraki, Atsushi; Naruse, Makoto; Nakamura, Shinichiro; Nakayama, Hirotaka; Kakue, Takashi; Shimobaba, Tomoyoshi; Ito, Tomoyoshi

2016-08-01

This is the first study to demonstrate that colour transformations in the volume of a photochromic material (PM) are induced at the intersections of two control light channels, one controlling PM colouration and the other controlling decolouration. Thus, PM colouration is induced by position selectivity, and therefore, a dynamic volumetric display may be realised using these two control lights. Moreover, a mixture of multiple PM types with different absorption properties exhibits different colours depending on the control light spectrum. Particularly, the spectrum management of the control light allows colour-selective colouration besides position selectivity. Therefore, a PM-based, full-colour volumetric display is realised. We experimentally construct a mixture of two PM types and validate the operating principles of such a volumetric display system. Our system is constructed simply by mixing multiple PM types; therefore, the display hardware structure is extremely simple, and the minimum size of a volume element can be as small as the size of a molecule. Volumetric displays can provide natural three-dimensional (3D) perception; therefore, the potential uses of our system include high-definition 3D visualisation for medical applications, architectural design, human-computer interactions, advertising, and entertainment.

MID-INFRARED SELECTION OF ACTIVE GALACTIC NUCLEI WITH THE WIDE-FIELD INFRARED SURVEY EXPLORER. I. CHARACTERIZING WISE-SELECTED ACTIVE GALACTIC NUCLEI IN COSMOS

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

Stern, Daniel; Assef, Roberto J.; Eisenhardt, Peter

2012-07-01

The Wide-field Infrared Survey Explorer (WISE) is an extremely capable and efficient black hole finder. We present a simple mid-infrared color criterion, W1 - W2 {>=} 0.8 (i.e., [3.4]-[4.6] {>=}0.8, Vega), which identifies 61.9 {+-} 5.4 active galactic nucleus (AGN) candidates per deg{sup 2} to a depth of W2 {approx} 15.0. This implies a much larger census of luminous AGNs than found by typical wide-area surveys, attributable to the fact that mid-infrared selection identifies both unobscured (type 1) and obscured (type 2) AGNs. Optical and soft X-ray surveys alone are highly biased toward only unobscured AGNs, while this simple WISEmore » selection likely identifies even heavily obscured, Compton-thick AGNs. Using deep, public data in the COSMOS field, we explore the properties of WISE-selected AGN candidates. At the mid-infrared depth considered, 160 {mu}Jy at 4.6 {mu}m, this simple criterion identifies 78% of Spitzer mid-infrared AGN candidates according to the criteria of Stern et al. and the reliability is 95%. We explore the demographics, multiwavelength properties and redshift distribution of WISE-selected AGN candidates in the COSMOS field.« less

Depth Of Modulation And Spot Size Selection In Bar-Code Laser Scanners

NASA Astrophysics Data System (ADS)

Barkan, Eric; Swartz, Jerome

1982-04-01

Many optical and electronic considerations enter into the selection of optical spot size in flying spot laser scanners of the type used in modern industrial and commerical environments. These include: the scale of the symbols to be read, optical background noise present in the symbol substrate, and factors relating to the characteristics of the signal processor. Many 'front ends' consist of a linear signal conditioner followed by nonlinear conditioning and digitizing circuitry. Although the nonlinear portions of the circuit can be difficult to characterize mathematically, it is frequently possible to at least give a minimum depth of modulation measure to yield a worst-case guarantee of adequate performance with respect to digitization accuracy. Depth of modulation actually delivered to the nonlinear circuitry will depend on scale, contrast, and noise content of the scanned symbol, as well as the characteristics of the linear conditioning circuitry (eg. transfer function and electronic noise). Time and frequency domain techniques are applied in order to estimate the effects of these factors in selecting a spot size for a given system environment. Results obtained include estimates of the effects of the linear front end transfer function on effective spot size and asymmetries which can affect digitization accuracy. Plots of convolution-computed modulation patterns and other important system properties are presented. Considerations are limited primarily to Gaussian spot profiles but also apply to more general cases. Attention is paid to realistic symbol models and to implications with respect to printing tolerances.

An optical water type framework for selecting and blending retrievals from bio-optical algorithms in lakes and coastal waters.

PubMed

Moore, Timothy S; Dowell, Mark D; Bradt, Shane; Verdu, Antonio Ruiz

2014-03-05

Bio-optical models are based on relationships between the spectral remote sensing reflectance and optical properties of in-water constituents. The wavelength range where this information can be exploited changes depending on the water characteristics. In low chlorophyll- a waters, the blue/green region of the spectrum is more sensitive to changes in chlorophyll- a concentration, whereas the red/NIR region becomes more important in turbid and/or eutrophic waters. In this work we present an approach to manage the shift from blue/green ratios to red/NIR-based chlorophyll- a algorithms for optically complex waters. Based on a combined in situ data set of coastal and inland waters, measures of overall algorithm uncertainty were roughly equal for two chlorophyll- a algorithms-the standard NASA OC4 algorithm based on blue/green bands and a MERIS 3-band algorithm based on red/NIR bands-with RMS error of 0.416 and 0.437 for each in log chlorophyll- a units, respectively. However, it is clear that each algorithm performs better at different chlorophyll- a ranges. When a blending approach is used based on an optical water type classification, the overall RMS error was reduced to 0.320. Bias and relative error were also reduced when evaluating the blended chlorophyll- a product compared to either of the single algorithm products. As a demonstration for ocean color applications, the algorithm blending approach was applied to MERIS imagery over Lake Erie. We also examined the use of this approach in several coastal marine environments, and examined the long-term frequency of the OWTs to MODIS-Aqua imagery over Lake Erie.

An optical water type framework for selecting and blending retrievals from bio-optical algorithms in lakes and coastal waters

PubMed Central

Moore, Timothy S.; Dowell, Mark D.; Bradt, Shane; Verdu, Antonio Ruiz

2014-01-01

Bio-optical models are based on relationships between the spectral remote sensing reflectance and optical properties of in-water constituents. The wavelength range where this information can be exploited changes depending on the water characteristics. In low chlorophyll-a waters, the blue/green region of the spectrum is more sensitive to changes in chlorophyll-a concentration, whereas the red/NIR region becomes more important in turbid and/or eutrophic waters. In this work we present an approach to manage the shift from blue/green ratios to red/NIR-based chlorophyll-a algorithms for optically complex waters. Based on a combined in situ data set of coastal and inland waters, measures of overall algorithm uncertainty were roughly equal for two chlorophyll-a algorithms—the standard NASA OC4 algorithm based on blue/green bands and a MERIS 3-band algorithm based on red/NIR bands—with RMS error of 0.416 and 0.437 for each in log chlorophyll-a units, respectively. However, it is clear that each algorithm performs better at different chlorophyll-a ranges. When a blending approach is used based on an optical water type classification, the overall RMS error was reduced to 0.320. Bias and relative error were also reduced when evaluating the blended chlorophyll-a product compared to either of the single algorithm products. As a demonstration for ocean color applications, the algorithm blending approach was applied to MERIS imagery over Lake Erie. We also examined the use of this approach in several coastal marine environments, and examined the long-term frequency of the OWTs to MODIS-Aqua imagery over Lake Erie. PMID:24839311

Test Operations Procedure (TOP) 6-3-044. Optical Transfer Function

DTIC Science & Technology

2009-07-27

Mounting Fixtures As required Alignment Periscope See section 4.1.6 TOP 6-3-040 27 July 2009 3 3. REQUIRED TEST CONDITIONS. 3.1 Pre-test...carefully selected. The stabilized cast iron lathe bed type, typically 2-3 m long, provides adequate support for mounting the various assemblies...combined size and weight of some vehicle mounted sights, a special mounting fixture , perhaps including a periscopic system may be required. It is

VizieR Online Data Catalog: Luminosity and redshift of galaxies from WISE/SDSS (Toba+, 2014)

NASA Astrophysics Data System (ADS)

Toba, Y.; Oyabu, S.; Matsuhara, H.; Malkan, M. A.; Gandhi, P.; Nakagawa, T.; Isobe, N.; Shirahata, M.; Oi, N.; Ohyama, Y.; Takita, S.; Yamauchi, C.; Yano, K.

2017-07-01

We selected 12 and 22 um flux-limited galaxies based on the WISE (Cat. II/311) and SDSS (Cat. II/294) catalogs, and these galaxies were then classified into five types according to their optical spectroscopic information in the SDSS catalog. For spectroscopically classified galaxies, we constructed the luminosity functions using the 1/Vmax method, considering the detection limit of the WISE and SDSS catalogs. (1 data file).

Development of Independent-type Optical CT

NASA Astrophysics Data System (ADS)

Yamaguchi, Tatsushi; Shiozawa, Daigoro; Rokunohe, Toshiaki; Kida, Junzo; Zhang, Wei

Optical current transformers (optical CTs) have features that they can be made much smaller and lighter than conventional electromagnetic induction transformers by their simple structure, and contribute to improvement of equipment reliability because of their excellent surge resistance performance. Authors consider optical CTs to be next generation transformers, and are conducting research and development of optical CTs aiming to apply to measuring and protection in electric power systems. Specifically we developed an independent-type optical CT by utilizing basic data of optical CTs accumulated for large current characteristics, temperature characteristics, vibration resistance characteristics, and so on. In performance verification, type tests complying with IEC standards, such as short-time current tests, insulation tests, accuracy tests, and so on, showed good results. This report describes basic principle and configuration of optical CTs. After that, as basic characteristics of optical CTs, conditions and results of verification tests for dielectric breakdown characteristics of sensor fibers, large current characteristics, temperature characteristics, and vibration resistance characteristics are described. Finally, development outline of the independent-type optical CT aiming to apply to all digital substation and its type tests results are described.

Polarization-selective optical transmission through a plasmonic metasurface.

PubMed

Pelzman, Charles; Cho, Sang-Yeon

2015-06-22

We present the design, fabrication, and experimental characterization of a nanoslit-based metasurface that offers polarization-selective optical transmission for advanced imaging applications. The metasurface consists of an array of meta-atoms, constructed with two orthogonally coupled subwavelength apertures. Highly enhanced optical transmission was achieved by selective excitation of surface plasmon waves on the metasurface. By rotating the orientation of the linearly polarized incident beam, switching of enhanced optical transmission bands through the metasurface was experimentally demonstrated. This demonstration is a significant step towards developing advanced multispectral imaging devices.

Polarization-selective optical transmission through a plasmonic metasurface

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

Pelzman, Charles; Cho, Sang-Yeon, E-mail: sangycho@nmsu.edu

2015-06-22

We present the design, fabrication, and experimental characterization of a nanoslit-based metasurface that offers polarization-selective optical transmission for advanced imaging applications. The metasurface consists of an array of meta-atoms, constructed with two orthogonally coupled subwavelength apertures. Highly enhanced optical transmission was achieved by selective excitation of surface plasmon waves on the metasurface. By rotating the orientation of the linearly polarized incident beam, switching of enhanced optical transmission bands through the metasurface was experimentally demonstrated. This demonstration is a significant step towards developing advanced multispectral imaging devices.

An Optical Biosensing Strategy Based on Selective Light Absorption and Wavelength Filtering from Chromogenic Reaction

PubMed Central

Chun, Hyeong Jin; Han, Yong Duk; Park, Yoo Min; Kim, Ka Ram; Lee, Seok Jae

2018-01-01

To overcome the time and space constraints in disease diagnosis via the biosensing approach, we developed a new signal-transducing strategy that can be applied to colorimetric optical biosensors. Our study is focused on implementation of a signal transduction technology that can directly translate the color intensity signals—that require complicated optical equipment for the analysis—into signals that can be easily counted with the naked eye. Based on the selective light absorption and wavelength-filtering principles, our new optical signaling transducer was built from a common computer monitor and a smartphone. In this signal transducer, the liquid crystal display (LCD) panel of the computer monitor served as a light source and a signal guide generator. In addition, the smartphone was used as an optical receiver and signal display. As a biorecognition layer, a transparent and soft material-based biosensing channel was employed generating blue output via a target-specific bienzymatic chromogenic reaction. Using graphics editor software, we displayed the optical signal guide patterns containing multiple polygons (a triangle, circle, pentagon, heptagon, and 3/4 circle, each associated with a specified color ratio) on the LCD monitor panel. During observation of signal guide patterns displayed on the LCD monitor panel using a smartphone camera via the target analyte-loaded biosensing channel as a color-filtering layer, the number of observed polygons changed according to the concentration of the target analyte via the spectral correlation between absorbance changes in a solution of the biosensing channel and color emission properties of each type of polygon. By simple counting of the changes in the number of polygons registered by the smartphone camera, we could efficiently measure the concentration of a target analyte in a sample without complicated and expensive optical instruments. In a demonstration test on glucose as a model analyte, we could easily measure the concentration of glucose in the range from 0 to 10 mM. PMID:29509682

An Optical Biosensing Strategy Based on Selective Light Absorption and Wavelength Filtering from Chromogenic Reaction.

PubMed

Chun, Hyeong Jin; Han, Yong Duk; Park, Yoo Min; Kim, Ka Ram; Lee, Seok Jae; Yoon, Hyun C

2018-03-06

To overcome the time and space constraints in disease diagnosis via the biosensing approach, we developed a new signal-transducing strategy that can be applied to colorimetric optical biosensors. Our study is focused on implementation of a signal transduction technology that can directly translate the color intensity signals-that require complicated optical equipment for the analysis-into signals that can be easily counted with the naked eye. Based on the selective light absorption and wavelength-filtering principles, our new optical signaling transducer was built from a common computer monitor and a smartphone. In this signal transducer, the liquid crystal display (LCD) panel of the computer monitor served as a light source and a signal guide generator. In addition, the smartphone was used as an optical receiver and signal display. As a biorecognition layer, a transparent and soft material-based biosensing channel was employed generating blue output via a target-specific bienzymatic chromogenic reaction. Using graphics editor software, we displayed the optical signal guide patterns containing multiple polygons (a triangle, circle, pentagon, heptagon, and 3/4 circle, each associated with a specified color ratio) on the LCD monitor panel. During observation of signal guide patterns displayed on the LCD monitor panel using a smartphone camera via the target analyte-loaded biosensing channel as a color-filtering layer, the number of observed polygons changed according to the concentration of the target analyte via the spectral correlation between absorbance changes in a solution of the biosensing channel and color emission properties of each type of polygon. By simple counting of the changes in the number of polygons registered by the smartphone camera, we could efficiently measure the concentration of a target analyte in a sample without complicated and expensive optical instruments. In a demonstration test on glucose as a model analyte, we could easily measure the concentration of glucose in the range from 0 to 10 mM.

Recent progress on mid-IR sensing with optical fibers

NASA Astrophysics Data System (ADS)

Kellner, Robert A.; Gobel, R.; Goetz, R.; Lendl, B.; Edl-Mizaikoff, B.; Tacke, Maurus; Katzir, Abraham

1995-09-01

Chemical sensors are analytical systems for the evaluation of compound- or ion-specific or - selective signals produced by specific or selective chemical reactions taking place at the interface between the chemically modified sensor surface and the substrate. The well known electrochemical sensing schemes have greatly contributed that sensors are considered now as the 'third supporting pillar of analytical chemistry' besides chromatography and spectroscopy. The aim of this paper is to describe the novel capabilities of chemical modified IR-transparent fibers as chemical IR-sensors for the on-line analysis of chlorinated hydrocarbons and organic compounds in aqueous solutions and gaseous mixtures, glucose, and sucrose in aqueous solution as developed in our laboratory. Moreover, the relative merits of this new method wil be depicted in comparison to other sensing techniques. Optical fiber sensors are novel analysis systems, based on molecular spectroscopy in the UV/VIS/IR-range. They benefit from the tremendous development in the field of optical fibers, an offspring of the telecommunication industry and the electronic revolution during the last few years. With the development of new materials besides the well known quartz fibers for the UV/VIS/NIR-range the optical window for fiber optic sensors was enlarged from 0,2 to 20 micrometers recently. The fiber length was increased recently to up to 2 meters for silver halides and approximately 10 meters for chalcogenides. New applications for environmental, food, and clinical sensing as well as process analysis are the driving force for modern research in IR-optical fiber sensors using mainly sapphire (Al2O3), chalcogenide (As-Se-Te) and silver halide (AgBr/AgCl) fibers and flow injection analysis (FIA) systems. Few representative examples for each of the various optical sensor types will be presented. Particular attention will be given to the use of silver halide fibers for the simultaneous determination of traces of chlorinated hydrocarbons in water and to FIA-systems for the process analysis of beverages.

Strain-engineered optoelectronic properties of 2D transition metal dichalcogenide lateral heterostructures

DOE PAGES

Lee, Jaekwang; Huang, Jingsong; Sumpter, Bobby G.; ...

2017-02-17

Compared with their bulk counterparts, 2D materials can sustain much higher elastic strain at which optical quantities such as bandgaps and absorption spectra governing optoelectronic device performance can be modified with relative ease. Using first-principles density functional theory and quasiparticle GW calculations, we demonstrate how uniaxial tensile strain can be utilized to optimize the electronic and optical properties of transition metal dichalcogenide lateral (in-plane) heterostructures such as MoX 2/WX 2 (X = S, Se, Te). We find that these lateral-type heterostructures may facilitate efficient electron–hole separation for light detection/harvesting and preserve their type II characteristic up to 12% of uniaxialmore » strain. Based on the strain-dependent bandgap and band offset, we show that uniaxial tensile strain can significantly increase the power conversion efficiency of these lateral heterostructures. Our results suggest that these strain-engineered lateral heterostructures are promising for optimizing optoelectronic device performance by selectively tuning the energetics of the bandgap.« less

A luminescence-optical spectroscopy study of Rb2KTiOF5 single crystals

NASA Astrophysics Data System (ADS)

Pustovarov, V. A.; Ogorodnikov, I. N.; Kozlov, A. V.; Isaenko, L. I.

2018-06-01

Large single crystals of Rb2KTiOF5 (RKTF), grown by slow solidification method, were studied (7-400 K) for various types of optical and radiation effects. The optical absorption spectra, the parameters of the Urbach rule at 293 K (σ = 0.24 and EU = 105 meV), the low-temperature reflection spectra (T = 7 K, E = 3.7-22 eV) were determined. The luminescence spectra (1.2-6.2 eV) and luminescence decay kinetics are studied upon excitation by a nanosecond electron beam (PCL), ultraviolet and vacuum ultraviolet light (PL), or X-rays radiation (XRL). PL excitation spectra under selective photoexcitation by synchrotron radiation (E = 3.7-22 eV, T = 7 K), temperature dependences of the intensity of steady-state XRL in different emission bands, as well as thermoluminescence (7-400 K) are studied. In the visible spectral region, we detected three luminescence bands that were attributed to radiative annihilation of intrinsic excitons (2.25 eV), recombination-type luminescence (2.1 eV) and luminescence of higher TiOF5 complexes (1.9 eV). The exponential component with lifetime of about 19 μs was revealed in the PCL decay kinetics at 2.25 eV. The low-energy onset of the intrinsic host absorption Ec = 3.55 eV was determined on the basis of the experimental data obtained. Spectra of optical constants were calculated by the Kramers-Krönig method, the energy of the onset of the interband transitions Eg = 4.2 eV was determined, and the main peaks of the optical spectra were identified.

Effect of capping agent on selectivity and sensitivity of CdTe quantum dots optical sensor for detection of mercury ions

NASA Astrophysics Data System (ADS)

Labeb, Mohmed; Sakr, Abdel-Hamed; Soliman, Moataz; Abdel-Fettah, Tarek M.; Ebrahim, Shaker

2018-05-01

Cadmium telluride (CdTe) quantum dots (QDs) were prepared from an aqueous solution containing CdCl2 and Te precursor in the presence of thioglycolic acid (TGA) or L-cysteine as capping agents. Two optical sensors have been developed for Hg2+ ions with very low concentration in the range of nanomolar (nM) or picomolar (pM) depending on the type of capping agents and based on photoluminescence (PL) quenching of CdTe QDs. It was observed that low concentrations of Hg2+ ions quench the fluorescence spectra of CdTe QDs and TGA capped CdTe QDs exhibited a linear response to Hg2+ ions in the concentration range from 1.25 to 10 nM. Moreover, it was found that L-cysteine capped CdTe QDs optical sensor with a sensitivity of 6 × 109 M-1, exhibited a linear coefficient of 0.99 and showed a detection limit of 2.7 pM in range from 5 to 25 pM of Hg2+ ions was achieved. In contrast to the significant response that was observed for Hg2+, a weak signal response was noted upon the addition of other metal ions indicating an excellent selectivity of CdTe QDs towards Hg2+.

Hydrodynamic Effects in Soft-matter Self-assembly: The Case of J-Aggregates of Amphiphilic Porphyrins.

PubMed

Ribo, Josep M; El-Hachemi, Zoubir; Arteaga, Oriol; Canillas, Adolf; Crusats, Joaquim

2017-07-01

Chiral J-aggregates of achiral amphiphilic porphyrins (4-sulfonatophenyl and aryl meso-substituted porphyrins) show several effects under the hydrodynamic forces of common stirring. These effects can be classified as pure mechanic (e. g. elasticity, plasticity and breaking of the self-assembly non-covalent bonding) and chemically selective as detected in the formation/growth of the nanoparticles. Diastereoselective, enantioselective and, depending on the sign of chiral shear forces, even enantiospecific selections have been described. Some types of these effects have been reported in other type of J-aggregates. Reversible and irreversible structural effects have been studied by atomic force imaging. The determination of the optical polarization properties (linear and circular) of their solutions is best done using Mueller matrix polarimetry methods. © 2017 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

A highly selective fluorescent chemosensor for CN- based on a novel bis(salamo)-type tetraoxime ligand

NASA Astrophysics Data System (ADS)

Wang, Fei; Gao, Lei; Zhao, Qing; Zhang, Yang; Dong, Wen-Kui; Ding, Yu-Jie

2018-02-01

The optical properties of a novel chemosensor for cyanide anions based on a symmetric bis(salamo)-type ligand (H3L) were investigated by UV-Vis and fluorescence spectroscopy in MeOH/H2O (1:1 v/v) solution. Sensor H3L can selectively sense CN- based on prominent color changes among other anions. The chemosensor exhibits an apparent fluorescence enhancement at 482 nm to CN- which because cyanide ions interact with Cdbnd N bonds. Combining the corrected Benesi-Hildebrand formula, the binding constant of the formed host-guest complex was calculated as 2.42 × 105 M- 1. Meanwhile, the detection limit of the sensor toward CN- was 8.91 × 10- 7 M. It is worth noting that the designed sensor can be used for rapid detection of cyanide anions in basic pH range, and has great practical value.

Solar internal lighting using optical collectors and fibers

NASA Astrophysics Data System (ADS)

Francini, F.; Fontani, D.; Jafrancesco, D.; Mercatelli, L.; Sansoni, P.

2006-08-01

A system exploiting solar energy, by means of optical collectors and fibres, has been applied for indoor illumination. The project has been called "The Sunflowers" for the property of solar collectors to track solar position during the day. Every "sunflower" contains several solar collectors, each of which is coupled to an optical fibre. The "Sunflower" is provided of mechanical systems and electric accessories for solar tracking. The light focused by the solar collector can be used in two possible ways: for internal illumination with direct solar light; otherwise it can be accumulated for lighting when the sun is not present. The first function is obtained coupling the optical collector to an optical fibre, which transports the solar light in selected points within the showcases. The second one consists in focusing solar light on a photovoltaic cell of the last generation type with high efficiency. In this configuration the photovoltaic cell converts the focused light into electric energy to be used for illumination in case of sun absence. A demonstrative installation has been realised applying this solar illumination system to museum lighting: a prototype has been tested in a prestigious museum in Florence.

A novel optical gating method for laser gated imaging

NASA Astrophysics Data System (ADS)

Ginat, Ran; Schneider, Ron; Zohar, Eyal; Nesher, Ofer

2013-06-01

For the past 15 years, Elbit Systems is developing time-resolved active laser-gated imaging (LGI) systems for various applications. Traditional LGI systems are based on high sensitive gated sensors, synchronized to pulsed laser sources. Elbit propriety multi-pulse per frame method, which is being implemented in LGI systems, improves significantly the imaging quality. A significant characteristic of the LGI is its ability to penetrate a disturbing media, such as rain, haze and some fog types. Current LGI systems are based on image intensifier (II) sensors, limiting the system in spectral response, image quality, reliability and cost. A novel propriety optical gating module was developed in Elbit, untying the dependency of LGI system on II. The optical gating module is not bounded to the radiance wavelength and positioned between the system optics and the sensor. This optical gating method supports the use of conventional solid state sensors. By selecting the appropriate solid state sensor, the new LGI systems can operate at any desired wavelength. In this paper we present the new gating method characteristics, performance and its advantages over the II gating method. The use of the gated imaging systems is described in a variety of applications, including results from latest field experiments.

Non-binary Colour Modulation for Display Device Based on Phase Change Materials.

PubMed

Ji, Hong-Kai; Tong, Hao; Qian, Hang; Hui, Ya-Juan; Liu, Nian; Yan, Peng; Miao, Xiang-Shui

2016-12-19

A reflective-type display device based on phase change materials is attractive because of its ultrafast response time and high resolution compared with a conventional display device. This paper proposes and demonstrates a unique display device in which multicolour changing can be achieved on a single device by the selective crystallization of double layer phase change materials. The optical contrast is optimized by the availability of a variety of film thicknesses of two phase change layers. The device exhibits a low sensitivity to the angle of incidence, which is important for display and colour consistency. The non-binary colour rendering on a single device is demonstrated for the first time using optical excitation. The device shows the potential for ultrafast display applications.

Fiber optic submarine cables cuts cost modeling and cable protection aspects

NASA Astrophysics Data System (ADS)

Al-Lawati, Ali

2015-03-01

This work presents a model to calculate costs associated with submarine fiber optic cable cuts. It accounts for both fixed and variable factors determining cost of fixing cables and restoring data transmission. It considers duration of a cut, capacity of fibers, number of fiber pairs and expected number of cuts during cable life time. Moreover, it provides templates for initial feasibility assessments by comparing cut costs to cost of different cable protection schemes. It offers a needed tool to assist in guiding decision makers in selecting type of cable, length and depth of cable burial in terms of increase in initial investment due to adapting such protection methods, and compare it to cost of cuts repair and alternative restoration paths for data.

Phase-locking of combination-cylinder discharge CO2 laser

NASA Astrophysics Data System (ADS)

Xu, Yonggen

2014-05-01

A new type of laser resonator is presented to obtained good coherent beam and the parameters of the laser beam are calculated. The principle of phase-locking is described based on the injection-locking, the properties of the injected beam in the resonator are studied in detail. The output beam from output mirror is an annular laser beam with zero central intensity. An analytical expression for the annular laser beam through the ABCD optical system is derived. Typical numerical examples are calculated to confirm our analytical results. It is shown that the good coherent beam can be obtained through phase-locking, and the central intensity of annular beam through ABCD optical system will become maximum when the parameters of laser beam are selected reasonably.

Biological samples on the ISS-EXPOSE facility for the ROSE/PUR experiment

NASA Astrophysics Data System (ADS)

Rontó, Gy.; Bérces, A.; Fekete, A.; Kerékgyártó, T.; Lammer, H.; Kargl, G.; Kömle, N. I.

2002-11-01

Three types of samples, bacteriophage T7, isolated phage DNA, polycrystalline uracil thin films were prepared in sandwich form that were closed vacuum-tightly with inert gaseous environment. The response of the samples to the following selected space environmental conditions was investigated: temperature (-20 - +40°C), vacuum, short wavelength UV irradiation. Uracil thin layer samples proved to be insensitive for temperature. In the vacuum chamber the structure of the samples in sandwich arrangement did not change. Irradiation with germicidal and Deuterium lamps caused a decrease in the optical density of the uracil layers and the decrease showed a saturation tendency in both cases. The dose-effect curves at germicidal lamp possess a saturation level at a lower optical density than at Deuterium.

Background-free balanced optical cross correlator

DOEpatents

Nejadmalayeri, Amir Hossein; Kaertner, Franz X

2014-12-23

A balanced optical cross correlator includes an optical waveguide, a first photodiode including a first n-type semiconductor and a first p-type semiconductor positioned about the optical waveguide on a first side of the optical waveguide's point of symmetry, and a second photodiode including a second n-type semiconductor and a second p-type semiconductor positioned about the optical waveguide on a second side of the optical waveguide's point of symmetry. A balanced receiver including first and second inputs is configured to produce an output current or voltage that reflects a difference in currents or voltages, originating from the first and the second photodiodes of the balanced cross correlator and fed to the first input and to the second input of the balanced receiver.

Fiber optics spectrochemical emission sensors

DOEpatents

Griffin, Jeffrey W.; Olsen, Khris B.

1992-01-01

A method of in situ monitoring of a body of a fluid stored in a tank or groundwater or vadose zone gases in a well for the presence of selected chemical species uses a probe insertable into the well or tank via a cable and having electrical apparatus for exciting selected chemical species in the body of fluid. The probe can have a pair of electrodes for initiating a spark or a plasma cell for maintaining a plasma to excite the selected chemical species. The probe also has optical apparatus for receiving optical emissions emitted by the excited species and optically transmitting the emissions via the cable to an analysis location outside the well. The analysis includes detecting a selected wavelength in the emissions indicative of the presence of the selected chemical species. A plurality of probes can be suspended at an end of a respective cable, with the transmitting and analyzing steps for each probe being synchronized sequentially for one set of support equipment and instrumentation to monitor at multiple test points. The optical apparatus is arranged about the light guide axis so that the selected chemical species are excited the fluid in alignment with the light guide axis and optical emissions are received from the excited chemical species along such axis.

Fiber optics spectrochemical emission sensors

DOEpatents

Griffin, J.W.; Olsen, K.B.

1992-02-04

A method is described of in situ monitoring of a body of a fluid stored in a tank or groundwater or vadose zone gases in a well for the presence of selected chemical species. The method uses a probe insertable into the well or tank via a cable and having an electrical apparatus for exciting selected chemical species in the body of fluid. The probe can have a pair of electrodes for initiating a spark or a plasma cell for maintaining a plasma to excite the selected chemical species. The probe also has an optical apparatus for receiving optical emissions emitted by the excited species and optically transmitting the emissions via the cable to an analysis location outside the well. The analysis includes detecting a selected wavelength in the emissions indicative of the presence of the selected chemical species. A plurality of probes can be suspended at an end of a respective cable, with the transmitting and analyzing steps for each probe being synchronized sequentially for one set of support equipment and instrumentation to monitor at multiple test points. The optical apparatus is arranged about the light guide axis so that the selected chemical species are excited in the fluid in alignment with the light guide axis. Optical emissions are received from the excited chemical species along such axis. 18 figs.

Adaptive optics images restoration based on frame selection and multi-framd blind deconvolution

NASA Astrophysics Data System (ADS)

Tian, Y.; Rao, C. H.; Wei, K.

2008-10-01

The adaptive optics can only partially compensate the image blurred by atmospheric turbulent due to the observing condition and hardware restriction. A post-processing method based on frame selection and multi-frame blind deconvolution to improve images partially corrected by adaptive optics is proposed. The appropriate frames which are picked out by frame selection technique is deconvolved. There is no priori knowledge except the positive constraint. The method has been applied in the image restoration of celestial bodies which were observed by 1.2m telescope equipped with 61-element adaptive optical system in Yunnan Observatory. The results showed that the method can effectively improve the images partially corrected by adaptive optics.

Optical filters for wavelength selection in fluorescence instrumentation.

PubMed

Erdogan, Turan

2011-04-01

Fluorescence imaging and analysis techniques have become ubiquitous in life science research, and they are poised to play an equally vital role in in vitro diagnostics (IVD) in the future. Optical filters are crucial for nearly all fluorescence microscopes and instruments, not only to provide the obvious function of spectral control, but also to ensure the highest possible detection sensitivity and imaging resolution. Filters make it possible for the sample to "see" light within only the absorption band, and the detector to "see" light within only the emission band. Without filters, the detector would not be able to distinguish the desired fluorescence from scattered excitation light and autofluorescence from the sample, substrate, and other optics in the system. Today the vast majority of fluorescence instruments, including the widely popular fluorescence microscope, use thin-film interference filters to control the spectra of the excitation and emission light. Hence, this unit emphasizes thin-film filters. After briefly introducing different types of thin-film filters and how they are made, the unit describes in detail different optical filter configurations in fluorescence instruments, including both single-color and multicolor imaging systems. Several key properties of thin-film filters, which can significantly affect optical system performance, are then described. In the final section, tunable optical filters are also addressed in a relative comparison.

The nature of X-ray selected star candidates

NASA Astrophysics Data System (ADS)

Mickaelian, A. M.; Paronyan, G. M.; Abrahamyan, H. V.; Gigoyan, K. S.; Gyulzadyan, M. V.; Kostandyan, G. R.

2016-12-01

The joint HRC/BHRC catalogue of optical identifications of ROSAT BSC and FSC X-ray sources is based on merging the Hamburg-ROSAT Catalogue (HRC) and Byurakan-Hamburg-ROSAT Catalogue (BHRC). Both have been made by optical identifications of X-ray sources based on low-dispersion spectra of the Hamburg QuasarSurvey (HQS) using the ROSAT Catalogues. HRC/BHRC contains a sample of 8132 (5341+2791) optically identified X-ray sources with count rate (CR) of photons ≥ 0.04 ct/s in the area of the low-dispersion Hamburg Quasar Survey (HQS), |b| ≥ 20° and δ ≥ 0°. Based on low-dispersion spectral classification, there are 4253 AGN, 492 galaxies, 1800 stars and 1587 unknown objects in the sample. 1800 star candidates include 1429 objects listed in SDSS DR12 photometric catalogue and 433 given in SDSS spectroscopic catalogue. Using these spectra, we have carried out classification of these star candidates to reveal new interesting objects, as well as to define the true content of our sample. 34 cataclysmic variables (including 7 new ones), 19 white dwarfs, 19 late-type stars (K-M and C types), 16 early type stars (O-B), 40 hot coronal stars (A-F types), 2 composite spectrum objects, and 17 bright stars have been revealed, as well as 286 objects which turned out to be extragalactic ones; 75 emission-line galaxies (HII/SB and AGN, including QSOs, Seyferts, and LINERs) and 211 absorption line galaxies were revealed (wrong classifications in HRC/BHRC due to their faint images and low-quality spectra). We have retrieved multiwavelength data from recent catalogues and carried out statistical investigations of the multiwavelength properties for the whole sample of stars. All stars have been found in GSC 2.3.2, as well as most of them are in GALEX, USNO-B1.0, 2MASS and WISE catalogues. Relations between the radiation fluxes in different bands from X-ray to radio for different types of sources are studied and analysis of their characteristics is made. X-ray selected stars are an important complement to the stellar populations of our Galaxy in solar neighbourhood and beyond. Keywords: X-ray sources, cross-correlations, white dwarfs, cataclysmic variables, carbon stars

Correlation between corneal thickness and optic disc morphology in normal tension glaucoma using modern technical analysis.

PubMed

Coman, Laurenţiu; Costescu, Monica; Alecu, Mihail; Coman, Oana Andreia

2014-01-01

The purpose of this study was to evaluate the relationship between central corneal thickness (CCT) and optic disc morphology in normal tension glaucoma (NTG). Patients with NTG underwent eye examination, optic disc imaging with Heildelberg Retina Tomograph II (HRT II) and ultrasound corneal pachymetry. The morphological parameters of the optic discs were used to classify the eyes into four groups: generalized enlargement (GE) type, myopic glaucomatous (MY) type, focal ischemic (FI) type and senile sclerotic (SS) type. A correlation between CCT and optic disc morphology obtained by HRT II was calculated. Multiple comparison and post hoc tests were performed in order to determine the significance of the differences between the four groups. The strongest correlation was between CCT and the parameters of optic disc imaging obtained at HRT II in the GE type of optic disc.

Pulse-Shaping-Based Nonlinear Microscopy: Development and Applications

NASA Astrophysics Data System (ADS)

Flynn, Daniel Christopher

The combination of optical microscopy and ultrafast spectroscopy make the spatial characterization of chemical kinetics on the femtosecond time scale possible. Commercially available octave-spanning Ti:Sapphire oscillators with sub-8 fs pulse durations can drive a multitude of nonlinear transitions across a significant portion of the visible spectrum with minimal average power. Unfortunately, dispersion from microscope objectives broadens pulse durations, decreases temporal resolution and lowers the peak intensities required for driving nonlinear transitions. In this dissertation, pulse shaping is used to compress laser pulses after the microscope objective. By using a binary genetic algorithm, pulse-shapes are designed to enable selective two-photon excitation. The pulse-shapes are demonstrated in two-photon fluorescence of live COS-7 cells expressing GFP-variants mAmetrine and tdTomato. The pulse-shaping approach is applied to a new multiphoton fluorescence resonance energy transfer (FRET) stoichiometry method that quantifies donor and acceptor molecules in complex, as well as the ratio of total donor to acceptor molecules. Compared to conventional multi-photon imaging techniques that require laser tuning or multiple laser systems to selectively excite individual fluorophores, the pulse-shaping approach offers rapid selective multifluorphore imaging at biologically relevant time scales. By splitting the laser beam into two beams and building a second pulse shaper, a pulse-shaping-based pump-probe microscope is developed. The technique offers multiple imaging modalities, such as excited state absorption (ESA), ground state bleach (GSB), and stimulated emission (SE), enhancing contrast of structures via their unique quantum pathways without the addition of contrast agents. Pulse-shaping based pump-probe microscopy is demonstrated for endogenous chemical-contrast imaging of red blood cells. In the second section of this dissertation, ultrafast spectroscopic techniques are used to characterize structure-function relationships of two-photon absorbing GFP-type probes and optical limiting materials. Fluorescence lifetimes of GFP-type probes are shown to depend on functional group substitution position, therefore, enabling the synthesis of designer probes for the possible study of conformation changes and aggregation in biological systems. Similarly, it is determined that small differences in the structure and dimensionality of organometallic macrocycles result in a diverse set of optical properties, which serves as a basis for the molecular level design of nonlinear optical materials.

Tidal Disruption Events: From iPTF to ZTF

NASA Astrophysics Data System (ADS)

Hung, Tiara; Gezari, Suvi; Cenko, Bradley; Kulkarni, Shri; Blagorodnova, Nadia; Yan, Lin

2018-01-01

The biggest challenge to finding tidal disruption events (TDEs) in optical transient sky surveys is to get rid of the numerous interlopers such as AGN and Type Ia supernovae that are at least 100 times more common. We will describe our selection process that led to the prompt discoveries of two TDEs (iPTF16axa and iPTF16fnl) in a 4-month long experiment to study nuclear transients in the intermediate Palomar Transient Factory (iPTF) together with UV and X-ray imaging follow-up from our Swift Cycle 12 Key Project. Subsequent multi-wavelength follow-up observations were triggered in order to study these rare events. We found that most of the optically-bright TDEs share similar peak luminosities, light curves, and temperature evolution except iPTF16fnl, which is the nearest, faintest, and fastest optical TDE ever found. Based on our detection rate in iPTF, we expect to discover ~30 TDEs in the first year of the Zwicky Transient Factory (ZTF), doubling the current TDE sample aggregated over ~7 years of wide-field optical surveys.

Highly selective optical fluoride ion sensor with submicromolar detection limit based on aluminum(III) octaethylporphyrin in thin polymeric film.

PubMed

Badr, Ibrahim H A; Meyerhoff, Mark E

2005-04-20

A highly selective, sensitive, and reversible fluoride optical sensing film based on aluminum(III)octaethylporphyrin as a fluoride ionophore and a lipophilic pH indicator as the optical transducer is described. The fluoride optical sensing films exhibit a submicromolar detection limit and high discrimination for fluoride over several lipophilic anions such as nitrate, perchlorate, and thiocyanate.

Effect of microemulsions on cell viability of human dermal fibroblasts

NASA Astrophysics Data System (ADS)

Li, Juyi; Mironava, Tatsiana; Simon, Marcia; Rafailovich, Miriam; Garti, Nissim

Microemulsions are optically clear, thermostable and isotropic mixture consisting of water, oil and surfactants. Their advantages of ease preparation, spontaneous formation, long-term stability and enhanced solubility of bioactive materials make them great potentials as vehicles in food and pharmaceutical applications. In this study, comparative in vitro cytotoxicity tests were performed to select a best formulation of microemulsion with the least toxicity for human dermal fibroblasts. Three different kinds of oils and six different kinds of surfactants were used to form microemulsions by different ratios. The effect of oil type and surfactant type as well as their proportions on cell proliferation and viability were tested.

An experimental investigation on the three-point bending behavior of composite laminate

NASA Astrophysics Data System (ADS)

A, Azzam; W, Li

2014-08-01

The response of composite laminate structure to three-point bending load was investigated by subjecting two types of stacking sequences of composite laminate structure by using electronic universal tester (Type: WDW-20) machine. Optical microscope was selected in order to characterize bending damage, delamination, and damage shapes in composite laminate structures. The results showed that the [0/90/-45/45]2s exhibits a brittle behavior, while other laminates exhibit a progressive failure mode consisting of fiber failure, debonding (splitting), and delamination. The [45/45/90/0]2s laminate has a highly nonlinear load- displacement curve due to compressive yielding.

VizieR Online Data Catalog: SPIRE observations of Herschel-BAT sample (Shimizu+, 2016)

NASA Astrophysics Data System (ADS)

Shimizu, T. T.; Melendez, M.; Mushotzky, R. F.; Koss, M. J.; Barger, A. J.; Cowie, L. L.

2016-09-01

We selected our sample of 313 AGN from the 58 month Swift/BAT Catalogue (https://swift.gsfc.nasa.gov/results/bs58mon) (Baumgartner et al., 2012, in prep.), imposing a redshift cutoff of z<0.05. All different types of AGN were chosen only excluding Blazars/BL Lac objects which most likely introduce complicated beaming effects. To determine their AGN type, for 252 sources we used the classifications from the BAT AGN Spectroscopic Survey (Koss et al., in preparation) which compiled and analysed optical spectra for the Swift/BAT 70 month catalogue (Berney et al., 2015MNRAS.454.3622B). (2 data files).

Combined Analysis of SENTINEL-1 and Rapideye Data for Improved Crop Type Classification: AN Early Season Approach for Rapeseed and Cereals

NASA Astrophysics Data System (ADS)

Lussem, U.; Hütt, C.; Waldhoff, G.

2016-06-01

Timely availability of crop acreage estimation is crucial for maintaining economic and ecological sustainability or modelling purposes. Remote sensing data has proven to be a reliable source for crop mapping and acreage estimation on parcel-level. However, when relying on a single source of remote sensing data, e.g. multispectral sensors like RapidEye or Landsat, several obstacles can hamper the desired outcome, for example cloud cover or haze. Another limitation may be a similarity in optical reflectance patterns of crops, especially in an early season approach by the end of March, early April. Usually, a reliable crop type map for winter-crops (winter wheat/rye, winter barley and rapeseed) in Central Europe can be obtained by using optical remote sensing data from late April to early May, given a full coverage of the study area and cloudless conditions. These prerequisites can often not be met. By integrating dual-polarimetric SAR-sensors with high temporal and spatial resolution, these limitations can be overcome. SAR-sensors are not influenced by clouds or haze and provide an additional source of information due to the signal-interaction with plant-architecture. The overall goal of this study is to investigate the contribution of Sentinel-1 SAR-data to regional crop type mapping for an early season map of disaggregated winter-crops for a subset of the Rur-Catchment in North Rhine-Westphalia (Germany). For this reason, RapidEye data and Sentinel-1 data are combined and the performance of Support Vector Machine and Maximum Likelihood classifiers are compared. Our results show that a combination of Sentinel-1 and RapidEye is a promising approach for most crops, but consideration of phenology for data selection can improve results. Thus the combination of optical and radar remote sensing data indicates advances for crop-type classification, especially when optical data availability is limited.

Temperature-dependent phase transition and comparative investigation on enhanced magnetic and optical properties between sillenite and perovskite bismuth ferrite-rGO nanocomposites

NASA Astrophysics Data System (ADS)

Jalil, M. A.; Chowdhury, Sayeed Shafayet; Alam Sakib, Mashnoon; Enamul Hoque Yousuf, S. M.; Khan Ashik, Emran; Firoz, Shakhawat H.; Basith, M. A.

2017-08-01

The manuscript reports the synthesis as well as a comparative investigation of the structural, magnetic, and optical properties between sillenite and perovskite type bismuth ferrite-reduced graphene oxide nanocomposites. Graphite oxide is prepared using the modified Hummers' method, followed by hydrothermal synthesis of bismuth ferrite-reduced graphene oxide nanocomposites at different reaction temperatures. The X-ray diffraction measurements confirm the formation of perovskite type BiFeO3-rGO nanocomposites at a reaction temperature of 200 °C. This is the lowest temperature to obtain perovskite type BiFeO3-rGO nanocomposites under the reaction procedure adopted, however, a structural transition to sillenite type Bi25FeO40-rGO is observed at 180 °C. The FESEM images demonstrate that the particle size of the perovskite nanocomposite is 25-60 nm, and for the sillenite phase nanocomposite it is 10-30 nm. The as-synthesized nanocomposites exhibit significantly enhanced saturation magnetization over pure BiFeO3 nanoparticles, with the sillenite Bi25FeO40-rGO nanocomposite having higher saturation magnetization than perovskite BiFeO3-rGO. The optical characteristics of the as-synthesized nanocomposites demonstrate considerably higher absorbance in the visible range with significantly lower band gap in comparison to undoped BiFeO3. Again, the sillenite Bi25FeO40-rGO nanocomposite is shown to have a lower band gap compared to the perovskite counterpart. Our investigation provides a means of selective phase formation as desired between sillenite Bi25FeO40-rGO and perovskite BiFeO3-rGO by controlling the hydrothermal reaction temperature. The outcome of our investigation suggests that the formation of nanocomposite of sillenite bismuth ferrite with reduced graphene oxide is promising to improve the magnetic and optical properties for potential technological applications.

Selective Optical Addressing of Nuclear Spins through Superhyperfine Interaction in Rare-Earth Doped Solids.

PubMed

Car, B; Veissier, L; Louchet-Chauvet, A; Le Gouët, J-L; Chanelière, T

2018-05-11

In Er^{3+}:Y_{2}SiO_{5}, we demonstrate the selective optical addressing of the ^{89}Y^{3+} nuclear spins through their superhyperfine coupling with the Er^{3+} electronic spins possessing large Landé g factors. We experimentally probe the electron-nuclear spin mixing with photon echo techniques and validate our model. The site-selective optical addressing of the Y^{3+} nuclear spins is designed by adjusting the magnetic field strength and orientation. This constitutes an important step towards the realization of long-lived solid-state qubits optically addressed by telecom photons.

Selective Optical Addressing of Nuclear Spins through Superhyperfine Interaction in Rare-Earth Doped Solids

NASA Astrophysics Data System (ADS)

Car, B.; Veissier, L.; Louchet-Chauvet, A.; Le Gouët, J.-L.; Chanelière, T.

2018-05-01

In Er3 +:Y2SiO5 , we demonstrate the selective optical addressing of the Y89 3 + nuclear spins through their superhyperfine coupling with the Er3 + electronic spins possessing large Landé g factors. We experimentally probe the electron-nuclear spin mixing with photon echo techniques and validate our model. The site-selective optical addressing of the Y3 + nuclear spins is designed by adjusting the magnetic field strength and orientation. This constitutes an important step towards the realization of long-lived solid-state qubits optically addressed by telecom photons.

Fiber optic vibration sensor

DOEpatents

Dooley, Joseph B.; Muhs, Jeffrey D.; Tobin, Kenneth W.

1995-01-01

A fiber optic vibration sensor utilizes two single mode optical fibers supported by a housing with one optical fiber fixedly secured to the housing and providing a reference signal and the other optical fiber having a free span length subject to vibrational displacement thereof with respect to the housing and the first optical fiber for providing a signal indicative of a measurement of any perturbation of the sensor. Damping or tailoring of the sensor to be responsive to selected levels of perturbation is provided by altering the diameter of optical fibers or by immersing at least a portion of the free span length of the vibration sensing optical fiber into a liquid of a selected viscosity.

Fiber optic vibration sensor

DOEpatents

Dooley, J.B.; Muhs, J.D.; Tobin, K.W.

1995-01-10

A fiber optic vibration sensor utilizes two single mode optical fibers supported by a housing with one optical fiber fixedly secured to the housing and providing a reference signal and the other optical fiber having a free span length subject to vibrational displacement thereof with respect to the housing and the first optical fiber for providing a signal indicative of a measurement of any perturbation of the sensor. Damping or tailoring of the sensor to be responsive to selected levels of perturbation is provided by altering the diameter of optical fibers or by immersing at least a portion of the free span length of the vibration sensing optical fiber into a liquid of a selected viscosity. 2 figures.

Evaluating the Assumptions of Surface Reflectance and Aerosol Type Selection Within the MODIS Aerosol Retrieval Over Land: The Problem of Dust Type Selection

NASA Technical Reports Server (NTRS)

Mielonen, T.; Levy, R. C.; Aaltonen, V.; Komppula, M.; de Leeuw, G.; Huttunen, J.; Lihavainen, H.; Kolmonen, P.; Lehtinen, K. E. J.; Arola, A.

2011-01-01

Aerosol Optical Depth (AOD) and Angstrom exponent (AE) values derived with the MODIS retrieval algorithm over land (Collection 5) are compared with ground based sun photometer measurements at eleven sites spanning the globe. Although, in general, total AOD compares well at these sites (R2 values generally over 0.8), there are cases (from 2 to 67% of the measurements depending on the site) where MODIS clearly retrieves the wrong spectral dependence, and hence, an unrealistic AE value. Some of these poor AE retrievals are due to the aerosol signal being too small (total AOD<0.3) but in other cases the AOD should have been high enough to derive accurate AE. However, in these cases, MODIS indicates AE values close to 0.6 and zero fine model weighting (FMW), i.e. dust model provides the best fitting to the MODIS observed reflectance. Yet, according to evidence from the collocated sun photometer measurements and back-trajectory analyses, there should be no dust present. This indicates that the assumptions about aerosol model and surface properties made by the MODIS algorithm may have been incorrect. Here we focus on problems related to parameterization of the land-surface optical properties in the algorithm, in particular the relationship between the surface reflectance at 660 and 2130 nm.

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

DOEpatents

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

1993-01-01

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

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

DOEpatents

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

1993-11-16

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

Optical properties of orthodontic aligners--spectrophotometry analysis of three types before and after aging.

PubMed

Lombardo, Luca; Arreghini, Angela; Maccarrone, Roberta; Bianchi, Anna; Scalia, Santo; Siciliani, Giuseppe

2015-01-01

The aim was to assess and compare absorbance and transmittance values of three types of clear orthodontic aligners before and after two cycles of in vitro aging. Nine samples of orthodontic aligners from three different manufacturers (Invisalign, Align Technology, Santa Clara, CA, USA; All-In, Micerium, Avegno, GE, Italy; F22 Aligner, Sweden & Martina, Due Carrare, PD, Italy) were selected, and each sample was subjected to spectrophotometry analysis of both its transmittance and absorbance a total of 27 times. Samples were subsequently aged in vitro at a constant temperature in artificial saliva supplemented with food colouring for two cycles of 14 days each. The spectrophotometry protocol was then repeated, and the resulting data were analysed and compared by means of ANOVA (p < 0.05). All types of aligners tested yielded lower transmittance and higher absorbance values after aging, but the difference was not significant in any case. That being said, the F22 aligners were found to be most transparent, both before and after aging, followed by Invisalign and All-In, and these differences were statistically significant. Commercial aligners possess significantly different optical, and therefore aesthetic, properties, both as delivered and following aging.

Two-color mixing for classifying agricultural products for safety and quality

NASA Astrophysics Data System (ADS)

Ding, Fujian; Chen, Yud-Ren; Chao, Kuanglin; Chan, Diane E.

2006-02-01

We show that the chromaticness of the visual signal that results from the two-color mixing achieved through an optically enhanced binocular device is directly related to the band ratio of light intensity at the two selected wavebands. A technique that implements the band-ratio criterion in a visual device by using two-color mixing is presented here. The device will allow inspectors to identify targets visually in accordance with a two-wavelength band ratio. It is a method of inspection by human vision assisted by an optical device, which offers greater flexibility and better cost savings than a multispectral machine vision system that implements the band-ratio criterion. With proper selection of the two narrow wavebands, discrimination by chromaticness that is directly related to the band ratio can work well. An example application of this technique for the inspection of carcasses chickens of afficted with various diseases is given. An optimal pair of wavelengths of 454 and 578 nm was selected to optimize differences in saturation and hue in CIE LUV color space among different types of target. Another example application, for the detection of chilling injury in cucumbers, is given, here the selected wavelength pair was 504 and 652 nm. The novel two-color mixing technique for visual inspection can be included in visual devices for various applications, ranging from target detection to food safety inspection.

The Global Implications of the Hard X-ray Excess in Type 1 AGN

NASA Astrophysics Data System (ADS)

Tatum, Malachi; Turner, T. J.; Miller, L.; Reeves, J. N.

2012-09-01

Suzaku observations of 1H 0419-577 and PDS 456 revealed a marked 'hard excess' of flux above 10 keV, likely due to the presence of a Compton-thick absorber covering a large fraction of the continuum source. The discovery is intriguing, given the clear view to the optical BLR in type 1 objects. These results motivated an exploratory study of the hard excess phenomenon in the local type 1 AGN population, using the Swift Burst Alert Telescope (BAT). We selected radio quiet type 1-1.9 AGN from the 58-month BAT catalog. The hardness of the X-ray spectrum, combined with measurements of the equivalent width of Fe Ka emission suggest that type 1 X-ray spectra are shaped by an ensemble of Compton-thick clouds, partially covering the continuum. I discuss our methodology, the observational findings & possible location of the Compton-thick gas.

Integrating optical satellite data and airborne laser scanning in habitat classification for wildlife management

NASA Astrophysics Data System (ADS)

Nijland, W.; Coops, N. C.; Nielsen, S. E.; Stenhouse, G.

2015-06-01

Wildlife habitat selection is determined by a wide range of factors including food availability, shelter, security and landscape heterogeneity all of which are closely related to the more readily mapped landcover types and disturbance regimes. Regional wildlife habitat studies often used moderate resolution multispectral satellite imagery for wall to wall mapping, because it offers a favourable mix of availability, cost and resolution. However, certain habitat characteristics such as canopy structure and topographic factors are not well discriminated with these passive, optical datasets. Airborne laser scanning (ALS) provides highly accurate three dimensional data on canopy structure and the underlying terrain, thereby offers significant enhancements to wildlife habitat mapping. In this paper, we introduce an approach to integrate ALS data and multispectral images to develop a new heuristic wildlife habitat classifier for western Alberta. Our method combines ALS direct measures of canopy height, and cover with optical estimates of species (conifer vs. deciduous) composition into a decision tree classifier for habitat - or landcover types. We believe this new approach is highly versatile and transferable, because class rules can be easily adapted for other species or functional groups. We discuss the implications of increased ALS availability for habitat mapping and wildlife management and provide recommendations for integrating multispectral and ALS data into wildlife management.

Optical data transmission technology for fixed and drag-on STS payload umbilicals, volume 2

NASA Technical Reports Server (NTRS)

St.denis, R. W.

1981-01-01

Optical data handling methods are studied as applicable to payload communications checkout and monitoring. Both payload umbilicals and interconnecting communication lines carrying payload data are examined for the following: (1) ground checkout requirements; (2) optical approach (technical survey of optical approaches, selection of optimum approach); (3) survey and select components; (4) compare with conventional approach; and (5) definition of follow on activity.

Compact wavelength-selective optical switch based on digital optical phase conjugation.

PubMed

Li, Zhiyang; Claver, Havyarimana

2013-11-15

In this Letter, we show that digital optical phase conjugation might be utilized to construct a new kind of wavelength-selective switches. When incorporated with a multimode interferometer, these switches have wide bandwidth, high tolerance for fabrication error, and low polarization dependency. They might help to build large-scale multiwavelength nonblocking switching systems, or even to fabricate an optical cross-connecting or routing system on a chip.

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

Yang, Jinyi; Wu, Xue-Bing; Wang, Feige

We present initial results from the first systematic survey of luminous z  ∼ 5.5 quasars. Quasars at z ∼ 5.5, the post-reionization epoch, are crucial tools to explore the evolution of intergalactic medium, quasar evolution, and the early super-massive black hole growth. However, it has been very challenging to select quasars at redshifts 5.3 ≤ z ≤ 5.7 using conventional color selections, due to their similar optical colors to late-type stars, especially M dwarfs, resulting in a glaring redshift gap in quasar redshift distributions. We develop a new selection technique for z ∼ 5.5 quasars based on optical, near-IR, and mid-IRmore » photometric data from Sloan Digital Sky Survey (SDSS), UKIRT InfraRed Deep Sky Surveys—Large Area Survey (ULAS), VISTA Hemisphere Survey (VHS), and Wide Field Infrared Survey Explorer . From our pilot observations in the SDSS-ULAS/VHS area, we have discovered 15 new quasars at 5.3 ≤ z ≤ 5.7 and 6 new lower redshift quasars, with SDSS z band magnitude brighter than 20.5. Including other two z ∼ 5.5 quasars already published in our previous work, we now construct a uniform quasar sample at 5.3 ≤ z ≤ 5.7, with 17 quasars in a ∼4800 square degree survey area. For further application in a larger survey area, we apply our selection pipeline to do a test selection by using the new wide field J-band photometric data from a preliminary version of the UKIRT Hemisphere Survey (UHS). We successfully discover the first UHS selected z ∼ 5.5 quasar.« less

Photonic Biosensor Assays to Detect and Distinguish Subspecies of Francisella tularensis

PubMed Central

Cooper, Kristie L.; Bandara, Aloka B.; Wang, Yunmiao; Wang, Anbo; Inzana, Thomas J.

2011-01-01

The application of photonic biosensor assays to diagnose the category-A select agent Francisella tularensis was investigated. Both interferometric and long period fiber grating sensing structures were successfully demonstrated; both these sensors are capable of detecting the optical changes induced by either immunological binding or DNA hybridization. Detection was made possible by the attachment of DNA probes or immunoglobulins (IgG) directly to the fiber surface via layer-by-layer electrostatic self-assembly. An optical fiber biosensor was tested using a standard transmission mode long period fiber grating of length 15 mm and period 260 μm, and coated with the IgG fraction of antiserum to F. tularensis. The IgG was deposited onto the optical fiber surface in a nanostructured film, and the resulting refractive index change was measured using spectroscopic ellipsometry. The presence of F. tularensis was detected from the decrease of peak wavelength caused by binding of specific antigen. Detection and differentiation of F. tularensis subspecies tularensis (type A strain TI0902) and subspecies holarctica (type B strain LVS) was further accomplished using a single-mode multi-cavity fiber Fabry-Perot interferometric sensor. These sensors were prepared by depositing seven polymer bilayers onto the fiber tip followed by attaching one of two DNA probes: (a) a 101-bp probe from the yhhW gene unique to type-A strains, or (b) a 117-bp probe of the lpnA gene, common to both type-A and type-B strains. The yhhW probe was reactive with the type-A, but not the type-B strain. Probe lpnA was reactive with both type-A and type-B strains. Nanogram quantities of the target DNA could be detected, highlighting the sensitivity of this method for DNA detection without the use of PCR. The DNA probe reacted with 100% homologous target DNA, but did not react with sequences containing 2-bp mismatches, indicating the high specificity of the assay. These assays will fill an important void that exists for rapid, culture-free, and field-compatible diagnosis of F. tularensis. PMID:22163782

Range Imaging without Moving Parts

NASA Technical Reports Server (NTRS)

Blair, J. Bryan; Scott, V. Stanley, III; Ramos-Izquierdo, Luis

2008-01-01

Range-imaging instruments of a type now under development are intended to generate the equivalent of three-dimensional images from measurements of the round-trip times of flight of laser pulses along known directions. These instruments could also provide information on characteristics of targets, including roughnesses and reflectivities of surfaces and optical densities of such semi-solid objects as trees and clouds. Unlike in prior range-imaging instruments based on times of flight along known directions, there would be no moving parts; aiming of the laser beams along the known directions would not be accomplished by mechanical scanning of mirrors, prisms, or other optical components. Instead, aiming would be accomplished by using solid-state devices to switch input and output beams along different fiber-optic paths. Because of the lack of moving parts, these instruments could be extraordinarily reliable, rugged, and long-lasting. An instrument of this type would include an optical transmitter that would send out a laser pulse along a chosen direction to a target. An optical receiver coaligned with the transmitter would measure the temporally varying intensity of laser light reflected from the target to determine the distance and surface characteristics of the target. The transmitter would be a combination of devices for generating precise directional laser illumination. It would include a pulsed laser, the output of which would be coupled into a fiber-optic cable with a fan-out and solid-state optical switches that would enable switching of the laser beam onto one or more optical fibers terminated at known locations in an array on a face at the focal plane of a telescope. The array would be imaged by the telescope onto the target space. The receiver optical system could share the aforementioned telescope with the transmitter or could include a separate telescope aimed in the same direction as that of the transmitting telescope. In either case, light reflected from the target would be focused by the receiver optical system onto an array of optical fibers matching the array in the transmitter. These optical fibers would couple the received light to one or more photodetector( s). Optionally, the receiver could include solid-state optical switches for choosing which optical fiber(s) would couple light to the photodetector(s). This instrument architecture is flexible and can be optimized for a wide variety of applications and levels of performance. For example, it is scalable to any number of pixels and pixel resolutions and is compatible with a variety of ranging and photodetection methodologies, including, for example, ranging by use of modulated (including pulsed and encoded) light signals. The use of fixed arrays of optical fibers to generate controlled illumination patterns would eliminate the mechanical complexity and much of the bulk of optomechanical scanning assemblies. Furthermore, digital control of the selection of the fiber-optic pathways for the transmitted beams could afford capabilities not seen in previous three-dimensional range-imaging systems. Instruments of this type could be specialized for use as, for example, proximity detectors, three-dimensional robotic vision systems, airborne terrain-mapping systems, and inspection systems.

Lateral access to the holes of photonic crystal fibers selective filling and sensing applications

NASA Astrophysics Data System (ADS)

Cordeiro, Cristiano M. B.; Dos Santos, Eliane M.; Brito Cruz, C. H.; de Matos, Christiano J.; Ferreiira, Daniel S.

2006-09-01

A new, simple, technique is demonstrated to laterally access the cladding holes of solid-core photonic crystal fibers (PCFs) or the central hole of hollow-core PCFs by blowing a hole through the fiber wall (using a fusion splicer and the application of pressure). For both fiber types material was subsequently and successfully inserted into the holes. The proposed method compares favorably with other reported selective filling techniques in terms of simplicity and reproducibility. Also, since the holes are laterally filled, simultaneous optical access to the PCFs is possible, which can prove useful for practical sensing applications. As a proof-of-concept experiment, Rhodamine fluorescence measurements are shown.

Optical signal splitting and chirping device modeling

NASA Astrophysics Data System (ADS)

Vinogradova, Irina L.; Andrianova, Anna V.; Meshkov, Ivan K.; Sultanov, Albert Kh.; Abdrakhmanova, Guzel I.; Grakhova, Elizaveta P.; Ishmyarov, Arsen A.; Yantilina, Liliya Z.; Kutlieva, Gulnaz R.

2017-04-01

This article examines the devices for optical signal splitting and chirping device modeling. Models with splitting and switching functions are taken into consideration. The described device for optical signal splitting and chirping represents interferential splitter with profiled mixer which provides allocation of correspondent spectral component from ultra wide band frequency diapason, and signal phase shift for aerial array (AA) directive diagram control. This paper proposes modeling for two types of devices for optical signal splitting and chirping: the interference-type optical signal splitting and chirping device and the long-distance-type optical signal splitting and chirping device.

Selection Algorithm for the CALIPSO Lidar Aerosol Extinction-to-Backscatter Ratio

NASA Technical Reports Server (NTRS)

Omar, Ali H.; Winker, David M.; Vaughan, Mark A.

2006-01-01

The extinction-to-backscatter ratio (S(sub a)) is an important parameter used in the determination of the aerosol extinction and subsequently the optical depth from lidar backscatter measurements. We outline the algorithm used to determine Sa for the Cloud and Aerosol Lidar and Infrared Pathfinder Spaceborne Observations (CALIPSO) lidar. S(sub a) for the CALIPSO lidar will either be selected from a look-up table or calculated using the lidar measurements depending on the characteristics of aerosol layer. Whenever suitable lofted layers are encountered, S(sub a) is computed directly from the integrated backscatter and transmittance. In all other cases, the CALIPSO observables: the depolarization ratio, delta, the layer integrated attenuated backscatter, beta, and the mean layer total attenuated color ratio, gamma, together with the surface type, are used to aid in aerosol typing. Once the type is identified, a look-up-table developed primarily from worldwide observations, is used to determine the S(sub a) value. The CALIPSO aerosol models include desert dust, biomass burning, background, polluted continental, polluted dust, and marine aerosols.

Optical data transmission technology for fixed and drag-on STS payloads umbilicals. Volume 1: Executive summary

NASA Technical Reports Server (NTRS)

St.denis, R. W.

1981-01-01

The feasibility of using optical data handling methods to transmit payload checkout and telemetry is discussed. Optical communications are superior to conventional communication systems for the following reasons: high data capacity optical channels; small and light weight optical cables; and optical signal immunity to electromagnetic interference. Task number one analyzed the ground checkout data requirements that may be expected from the payload community. Task number two selected the optical approach based on the interface requirements, the location of the interface, the amount of time required to reconfigure hardware, and the method of transporting the optical signal. Task number three surveyed and selected optical components for the two payload data link. Task number four makes a qualitative comparison of the conventional electrical communication system and the proposed optical communication system.

Optical filter selection for high confidence discrimination of strongly overlapping infrared chemical spectra.

PubMed

Major, Kevin J; Poutous, Menelaos K; Ewing, Kenneth J; Dunnill, Kevin F; Sanghera, Jasbinder S; Aggarwal, Ishwar D

2015-09-01

Optical filter-based chemical sensing techniques provide a new avenue to develop low-cost infrared sensors. These methods utilize multiple infrared optical filters to selectively measure different response functions for various chemicals, dependent on each chemical's infrared absorption. Rather than identifying distinct spectral features, which can then be used to determine the identity of a target chemical, optical filter-based approaches rely on measuring differences in the ensemble response between a given filter set and specific chemicals of interest. Therefore, the results of such methods are highly dependent on the original optical filter choice, which will dictate the selectivity, sensitivity, and stability of any filter-based sensing method. Recently, a method has been developed that utilizes unique detection vector operations defined by optical multifilter responses, to discriminate between volatile chemical vapors. This method, comparative-discrimination spectral detection (CDSD), is a technique which employs broadband optical filters to selectively discriminate between chemicals with highly overlapping infrared absorption spectra. CDSD has been shown to correctly distinguish between similar chemicals in the carbon-hydrogen stretch region of the infrared absorption spectra from 2800-3100 cm(-1). A key challenge to this approach is how to determine which optical filter sets should be utilized to achieve the greatest discrimination between target chemicals. Previous studies used empirical approaches to select the optical filter set; however this is insufficient to determine the optimum selectivity between strongly overlapping chemical spectra. Here we present a numerical approach to systematically study the effects of filter positioning and bandwidth on a number of three-chemical systems. We describe how both the filter properties, as well as the chemicals in each set, affect the CDSD results and subsequent discrimination. These results demonstrate the importance of choosing the proper filter set and chemicals for comparative discrimination, in order to identify the target chemical of interest in the presence of closely matched chemical interferents. These findings are an integral step in the development of experimental prototype sensors, which will utilize CDSD.

Aerosol-type retrieval and uncertainty quantification from OMI data

NASA Astrophysics Data System (ADS)

Kauppi, Anu; Kolmonen, Pekka; Laine, Marko; Tamminen, Johanna

2017-11-01

We discuss uncertainty quantification for aerosol-type selection in satellite-based atmospheric aerosol retrieval. The retrieval procedure uses precalculated aerosol microphysical models stored in look-up tables (LUTs) and top-of-atmosphere (TOA) spectral reflectance measurements to solve the aerosol characteristics. The forward model approximations cause systematic differences between the modelled and observed reflectance. Acknowledging this model discrepancy as a source of uncertainty allows us to produce more realistic uncertainty estimates and assists the selection of the most appropriate LUTs for each individual retrieval.This paper focuses on the aerosol microphysical model selection and characterisation of uncertainty in the retrieved aerosol type and aerosol optical depth (AOD). The concept of model evidence is used as a tool for model comparison. The method is based on Bayesian inference approach, in which all uncertainties are described as a posterior probability distribution. When there is no single best-matching aerosol microphysical model, we use a statistical technique based on Bayesian model averaging to combine AOD posterior probability densities of the best-fitting models to obtain an averaged AOD estimate. We also determine the shared evidence of the best-matching models of a certain main aerosol type in order to quantify how plausible it is that it represents the underlying atmospheric aerosol conditions.The developed method is applied to Ozone Monitoring Instrument (OMI) measurements using a multiwavelength approach for retrieving the aerosol type and AOD estimate with uncertainty quantification for cloud-free over-land pixels. Several larger pixel set areas were studied in order to investigate the robustness of the developed method. We evaluated the retrieved AOD by comparison with ground-based measurements at example sites. We found that the uncertainty of AOD expressed by posterior probability distribution reflects the difficulty in model selection. The posterior probability distribution can provide a comprehensive characterisation of the uncertainty in this kind of problem for aerosol-type selection. As a result, the proposed method can account for the model error and also include the model selection uncertainty in the total uncertainty budget.

Acoustic force mapping in a hybrid acoustic-optical micromanipulation device supporting high resolution optical imaging† †Electronic supplementary information (ESI) available: Additional information about 1D model calculations for a piezoelectric transducer. See DOI: 10.1039/c6lc00182c Click here for additional data file.

PubMed Central

McDougall, Craig; MacDonald, Michael Peter; Ritsch-Marte, Monika

2016-01-01

Many applications in the life-sciences demand non-contact manipulation tools for forceful but nevertheless delicate handling of various types of sample. Moreover, the system should support high-resolution optical imaging. Here we present a hybrid acoustic/optical manipulation system which utilizes a transparent transducer, making it compatible with high-NA imaging in a microfluidic environment. The powerful acoustic trapping within a layered resonator, which is suitable for highly parallel particle handling, is complemented by the flexibility and selectivity of holographic optical tweezers, with the specimens being under high quality optical monitoring at all times. The dual acoustic/optical nature of the system lends itself to optically measure the exact acoustic force map, by means of direct force measurements on an optically trapped particle. For applications with (ultra-)high demand on the precision of the force measurements, the position of the objective used for the high-NA imaging may have significant influence on the acoustic force map in the probe chamber. We have characterized this influence experimentally and the findings were confirmed by model simulations. We show that it is possible to design the chamber and to choose the operating point in such a way as to avoid perturbations due to the objective lens. Moreover, we found that measuring the electrical impedance of the transducer provides an easy indicator for the acoustic resonances. PMID:27025398

The Las Campanas Infrared Survey - II. Photometric redshifts, comparison with models and clustering evolution

NASA Astrophysics Data System (ADS)

Firth, A. E.; Somerville, R. S.; McMahon, R. G.; Lahav, O.; Ellis, R. S.; Sabbey, C. N.; McCarthy, P. J.; Chen, H.-W.; Marzke, R. O.; Wilson, J.; Abraham, R. G.; Beckett, M. G.; Carlberg, R. G.; Lewis, J. R.; Mackay, C. D.; Murphy, D. C.; Oemler, A. E.; Persson, S. E.

2002-05-01

The Las Campanas Infrared (LCIR) Survey, using the Cambridge Infra-Red Survey Instrument (CIRSI), reaches H ~21 over nearly 1deg2 . In this paper we present results from 744arcmin2 centred on the Hubble Deep Field South for which UBVRI optical data are publicly available. Making conservative magnitude cuts to ensure spatial uniformity, we detect 3177 galaxies to H =20.0 in 744arcmin2 and a further 842 to H =20.5 in a deeper subregion of 407arcmin2 . We compare the observed optical-infrared (IR) colour distributions with the predictions of semi-analytic hierarchical models and find reasonable agreement. We also determine photometric redshifts, finding a median redshift of ~0.55. We compare the redshift distributions N (z ) of E, Sbc, Scd and Im spectral types with models, showing that the observations are inconsistent with simple passive-evolution models while semi-analytic models provide a reasonable fit to the total N (z ) but underestimate the number of z ~1 red spectral types relative to bluer spectral types. We also present N (z ) for samples of extremely red objects (EROs) defined by optical-IR colours. We find that EROs with R -H >4 and H <20.5 have a median redshift z m ~1 while redder colour cuts have slightly higher z m . In the magnitude range 194 comprise ~18 per cent of the observed galaxy population, while in semi-analytic models they contribute only ~4 per cent. We also determine the angular correlation function w (θ ) for magnitude, colour, spectral type and photometric redshift-selected subsamples of the data and use the photometric redshift distributions to derive the spatial clustering statistic ξ (r ) as a function of spectral type and redshift out to z ~1.2. Parametrizing ξ (r ) by ξ (r c ,z )=[r c /r *(z )]-1.8 , where r c is in comoving coordinates, we find that r *(z ) increases by a factor of 1.5-2 from z =0 to z ~1.2. We interpret this as a selection effect - the galaxies selected at z ~1.2 are intrinsically very luminous, about 1-1.5mag brighter than L *. When galaxies are selected by absolute magnitude, we find no evidence for evolution in r * over this redshift range. Extrapolated to z =0, we find r *(z =0)~6.5h -1 Mpc for red galaxies and r *(z =0)~2-4h -1 Mpc for blue galaxies. We also find that, while the angular clustering amplitude of EROs with R -H >4 or I -H >3 is up to four times that of the whole galaxy population, the spatial clustering length r *(z =1) is ~7.5-10.5h -1 Mpc, which is only a factor of ~1.7 times r *(z =1) for R -H <4 and I -H <3 galaxies lying in a similar redshift and luminosity range. This difference is similar to that observed between red and blue galaxies at low redshifts.

The influence of the quantum dot/polymethylmethacrylate composite preparation method on the stability of its optical properties under laser radiation

NASA Astrophysics Data System (ADS)

Zvaigzne, M. A.; Martynov, I. L.; Krivenkov, V. A.; Samokhvalov, P. S.; Nabiev, I. R.

2017-01-01

Photoluminescent semiconductor nanocrystals, quantum dots (QDs), are nowadays one of the most promising materials for developing a new generation of fluorescent labels, new types of light-emitting devices and displays, flexible electronic components, and solar panels. In many areas the use of QDs is associated with an intense optical excitation, which, in the case of a prolonged exposure, often leads to changes in their optical characteristics. In the present work we examined how the method of preparation of quantum dot/polymethylmethacrylate (QD/PMMA) composite influenced the stability of the optical properties of QD inside the polymer matrix under irradiation by different laser harmonics in the UV (355 nm) and visible (532 nm) spectral regions. The composites were synthesized by spin-coating and radical polymerization methods. Experiments with the samples obtained by spin-coating showed that the properties of the QD/PMMA films remain almost constant at values of the radiation dose below 10 fJ per particle. Irradiating the composites prepared by the radical polymerization method, we observed a monotonic increase in the luminescence quantum yield (QY) accompanied by an increase in the luminescence decay time regardless of the wavelength of the incident radiation. We assume that the observed difference in the optical properties of the samples under exposure to laser radiation is associated with the processes occurring during radical polymerization, in particular, with charge transfer from the radical particles inside QDs. The results of this study are important for understanding photophysical properties of composites on the basis of QDs, as well as for selection of the type of polymer and the composite synthesis method with quantum dots that would allow one to avoid the degradation of their luminescence.

Fiber Optic Distributed Sensors for High-resolution Temperature Field Mapping.

PubMed

Lomperski, Stephen; Gerardi, Craig; Lisowski, Darius

2016-11-07

The reliability of computational fluid dynamics (CFD) codes is checked by comparing simulations with experimental data. A typical data set consists chiefly of velocity and temperature readings, both ideally having high spatial and temporal resolution to facilitate rigorous code validation. While high resolution velocity data is readily obtained through optical measurement techniques such as particle image velocimetry, it has proven difficult to obtain temperature data with similar resolution. Traditional sensors such as thermocouples cannot fill this role, but the recent development of distributed sensing based on Rayleigh scattering and swept-wave interferometry offers resolution suitable for CFD code validation work. Thousands of temperature measurements can be generated along a single thin optical fiber at hundreds of Hertz. Sensors function over large temperature ranges and within opaque fluids where optical techniques are unsuitable. But this type of sensor is sensitive to strain and humidity as well as temperature and so accuracy is affected by handling, vibration, and shifts in relative humidity. Such behavior is quite unlike traditional sensors and so unconventional installation and operating procedures are necessary to ensure accurate measurements. This paper demonstrates implementation of a Rayleigh scattering-type distributed temperature sensor in a thermal mixing experiment involving two air jets at 25 and 45 °C. We present criteria to guide selection of optical fiber for the sensor and describe installation setup for a jet mixing experiment. We illustrate sensor baselining, which links readings to an absolute temperature standard, and discuss practical issues such as errors due to flow-induced vibration. This material can aid those interested in temperature measurements having high data density and bandwidth for fluid dynamics experiments and similar applications. We highlight pitfalls specific to these sensors for consideration in experiment design and operation.

H-ATLAS/GAMA: the nature and characteristics of optically red galaxies detected at submillimetre wavelengths

NASA Astrophysics Data System (ADS)

Dariush, A.; Dib, S.; Hony, S.; Smith, D. J. B.; Zhukovska, S.; Dunne, L.; Eales, S.; Andrae, E.; Baes, M.; Baldry, I.; Bauer, A.; Bland-Hawthorn, J.; Brough, S.; Bourne, N.; Cava, A.; Clements, D.; Cluver, M.; Cooray, A.; De Zotti, G.; Driver, S.; Grootes, M. W.; Hopkins, A. M.; Hopwood, R.; Kaviraj, S.; Kelvin, L.; Lara-Lopez, M. A.; Liske, J.; Loveday, J.; Maddox, S.; Madore, B.; Michałowski, M. J.; Pearson, C.; Popescu, C.; Robotham, A.; Rowlands, K.; Seibert, M.; Shabani, F.; Smith, M. W. L.; Taylor, E. N.; Tuffs, R.; Valiante, E.; Virdee, J. S.

2016-02-01

We combine Herschel/SPIRE submillimetre (submm) observations with existing multiwavelength data to investigate the characteristics of low-redshift, optically red galaxies detected in submm bands. We select a sample of galaxies in the redshift range 0.01 ≤ z ≤ 0.2, having >5σ detections in the SPIRE 250 μm submm waveband. Sources are then divided into two sub-samples of red and blue galaxies, based on their UV-optical colours. Galaxies in the red sample account for ≈4.2 per cent of the total number of sources with stellar masses M* ≳ 1010 M⊙. Following visual classification of the red galaxies, we find that ≳30 per cent of them are early-type galaxies and ≳40 per cent are spirals. The colour of the red-spiral galaxies could be the result of their highly inclined orientation and/or a strong contribution of the old stellar population. It is found that irrespective of their morphological types, red and blue sources occupy environments with more or less similar densities (I.e. the Σ5 parameter). From the analysis of the spectral energy distributions of galaxies in our samples based on MAGPHYS, we find that galaxies in the red sample (of any morphological type) have dust masses similar to those in the blue sample (I.e. normal spiral/star-forming systems). However, in comparison to the red-spirals and in particular blue systems, red-ellipticals have lower mean dust-to-stellar mass ratios. Besides galaxies in the red-elliptical sample have much lower mean star formation/specific star formation rates in contrast to their counterparts in the blue sample. Our results support a scenario where dust in early-type systems is likely to be of an external origin.

Flight Integral Field Spectrograph (IFS) Optical Design for WFIRST Coronagraphic Exoplanet Demonstration

NASA Technical Reports Server (NTRS)

Gong, Qian; Groff, Tyler D.; Zimmerman, Neil; Mandell, Avi; McElwain, Michael; Rizzo, Maxime; Saxena, Prabal

2017-01-01

Based on the experience from Prototype Imaging Spectrograph for Coronagraphic Exoplanet Studies (PISCES) for WFIRST, we have moved to the flight instrument design phase. The specifications for flight IFS have similarities and differences from the prototype. This paper starts with the science and system requirement, discusses a number of critical trade-offs: such as IFS type selection, lenslet array shape and layout versus detector pixel accuracy, how to accommodate the larger Field Of View (FOV) and wider wavelength band for a potential add-on StarShade occulter. Finally, the traditional geometric optical design is also investigated and traded: reflective versus refractive, telecentric versus non-telecentric relay. The relay before the lenslet array controls the chief angle distribution on the lenslet array. Our previous paper has addressed how the relay design combined with lenslet arraypinhole mask can further compress the residual star light and increase the contrast. Finally, a complete phase A IFS optical design is presented.

The model of the optical-electronic control system of vehicles location at level crossing

NASA Astrophysics Data System (ADS)

Verezhinskaia, Ekaterina A.; Gorbachev, Aleksei A.; Maruev, Ivan A.; Shavrygina, Margarita A.

2016-04-01

Level crossing - one of the most dangerous sections of the road network, where railway line crosses motor road at the same level. The collision of trains with vehicles at a level crossing is a serious type of road traffic accidents. The purpose of this research is to develop complex optical electronic control system of vehicles location in the dangerous zone of level crossing. The system consists of registration blocks (including photodetector, lens, infrared emitting diode), determinant devices and camera installed within the boundaries of level crossing. The system performs detection of objects (vehicles) by analysing the time of the object movement opposite to the registration block and level of the reflected signal from the object. The paper presents theoretical description and experimental research of main principles of the system operation. Experimental research of the system model with selected optical-electronic components have confirmed the possibility of metal objects detection at the required distance (0.5 - 2 m) with different values of background illuminance.

Method and apparatus for determining minority carrier diffusion length in semiconductors

DOEpatents

Goldstein, Bernard; Dresner, Joseph; Szostak, Daniel J.

1983-07-12

Method and apparatus are provided for determining the diffusion length of minority carriers in semiconductor material, particularly amorphous silicon which has a significantly small minority carrier diffusion length using the constant-magnitude surface-photovoltage (SPV) method. An unmodulated illumination provides the light excitation on the surface of the material to generate the SPV. A manually controlled or automatic servo system maintains a constant predetermined value of the SPV. A vibrating Kelvin method-type probe electrode couples the SPV to a measurement system. The operating optical wavelength of an adjustable monochromator to compensate for the wavelength dependent sensitivity of a photodetector is selected to measure the illumination intensity (photon flux) on the silicon. Measurements of the relative photon flux for a plurality of wavelengths are plotted against the reciprocal of the optical absorption coefficient of the material. A linear plot of the data points is extrapolated to zero intensity. The negative intercept value on the reciprocal optical coefficient axis of the extrapolated linear plot is the diffusion length of the minority carriers.

Inversion Schemes to Retrieve Atmospheric and Oceanic Parameters from SeaWiFS Data

NASA Technical Reports Server (NTRS)

Deschamps, P.-Y.; Frouin, R.

1997-01-01

The investigation focuses on two key issues in satellite ocean color remote sensing, namely the presence of whitecaps on the sea surface and the validity of the aerosol models selected for the atmospheric correction of SeaWiFS data. Experiments were designed and conducted at the Scripps Institution of Oceanography to measure the optical properties of whitecaps and to study the aerosol optical properties in a typical mid-latitude coastal environment. CIMEL Electronique sunphotometers, now integrated in the AERONET network, were also deployed permanently in Bermuda and in Lanai, calibration/validation sites for SeaWiFS and MODIS. Original results were obtained on the spectral reflectance of whitecaps and on the choice of aerosol models for atmospheric correction schemes and the type of measurements that should be made to verify those schemes. Bio-optical algorithms to remotely sense primary productivity from space were also evaluated, as well as current algorithms to estimate PAR at the earth's surface.

Femtosecond optical polarization switching using a cadmium oxide-based perfect absorber

DOE PAGES

Yang, Yuanmu; Kelley, Kyle; Sachet, Edward; ...

2017-05-01

Ultrafast control of the polarization state of light may enable a plethora of applications in optics, chemistry and biology. However, conventional polarizing elements, such as polarizers and waveplates, are either static or possess only gigahertz switching speeds. Here, with the aid of high-mobility indium-doped cadmium oxide (CdO) as the gateway plasmonic material, we realize a high-quality factor Berreman-type perfect absorber at a wavelength of 2.08 μm. On sub-bandgap optical pumping, the perfect absorption resonance strongly redshifts because of the transient increase of the ensemble-averaged effective electron mass of CdO, which leads to an absolute change in the p-polarized reflectance frommore » 1.0 to 86.3%. As a result, by combining the exceedingly high modulation depth with the polarization selectivity of the perfect absorber, we experimentally demonstrate a reflective polarizer with a polarization extinction ratio of 91 that can be switched on and off within 800 fs.« less

Femtosecond optical polarization switching using a cadmium oxide-based perfect absorber

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

Yang, Yuanmu; Kelley, Kyle; Sachet, Edward

Ultrafast control of the polarization state of light may enable a plethora of applications in optics, chemistry and biology. However, conventional polarizing elements, such as polarizers and waveplates, are either static or possess only gigahertz switching speeds. Here, with the aid of high-mobility indium-doped cadmium oxide (CdO) as the gateway plasmonic material, we realize a high-quality factor Berreman-type perfect absorber at a wavelength of 2.08 μm. On sub-bandgap optical pumping, the perfect absorption resonance strongly redshifts because of the transient increase of the ensemble-averaged effective electron mass of CdO, which leads to an absolute change in the p-polarized reflectance frommore » 1.0 to 86.3%. As a result, by combining the exceedingly high modulation depth with the polarization selectivity of the perfect absorber, we experimentally demonstrate a reflective polarizer with a polarization extinction ratio of 91 that can be switched on and off within 800 fs.« less

Order parameter description of walk-off effect on pattern selection in degenerate optical parametric oscillators

NASA Astrophysics Data System (ADS)

Taki, Majid; San Miguel, Maxi; Santagiustina, Marco

2000-02-01

Degenerate optical parametric oscillators can exhibit both uniformly translating fronts and nonuniformly translating envelope fronts under the walk-off effect. The nonlinear dynamics near threshold is shown to be described by a real convective Swift-Hohenberg equation, which provides the main characteristics of the walk-off effect on pattern selection. The predictions of the selected wave vector and the absolute instability threshold are in very good quantitative agreement with numerical solutions found from the equations describing the optical parametric oscillator.

A versatile optical microscope for time-dependent single-molecule and single-particle spectroscopy

NASA Astrophysics Data System (ADS)

Li, Hao; Yang, Haw

2018-03-01

This work reports the design and implementation of a multi-function optical microscope for time-dependent spectroscopy on single molecules and single nanoparticles. It integrates the now-routine single-object measurements into one standalone platform so that no reconfiguration is needed when switching between different types of sample or spectroscopy modes. The illumination modes include evanescent field through total internal reflection, dark-field illumination, and epi-excitation onto a diffraction-limited spot suitable for confocal detection. The detection modes include spectrally resolved line imaging, wide-field imaging with dual-color capability, and two-color single-element photon-counting detection. The switch between different spectroscopy and data acquisition modes is fully automated and executed through computer programming. The capability of this microscope is demonstrated through selected proof-of-principle experiments.

A sandwich-type optical immunosensor based on the alkaline phosphatase enzyme for Salmonella thypimurium detection

NASA Astrophysics Data System (ADS)

Widyastuti, E.; Puspitasari Schonherr, M. F.; Masruroh, A.; Anggraeni, R. A.; Nisak, Y. K.; Mursidah, S.

2018-03-01

Salmonella is pathogenic bacteria that caused foodborne diseases which being called Salmonellosis. Prevalence of Salmonellosis that being caused by Salmonella thypimurium in Indonesia is quite high. However, detection of Salmonella bacteria in food still limited, complicated, and required a lot time. Sensitive optical assay for Salmonella thypimurium paper based detection has been developed by integrating sandwich assay between antibody-antigen complex and alkaline phosphatase enzyme that produce visible bluish-purple colour with presence of NBT-BCIP substrate. The results showed that Limit of Quantitation of detection is 105 CFU mL-1 with detection time 15 minutes. Linearity test between Colour intensity that produced from Salmonella concentration presence on samples showed that detection has good linearity. Selectivity test exhibited excellent sensitivity with good discrimination against Escherichia coli.

Optical properties of porous polylactide scaffolds

NASA Astrophysics Data System (ADS)

Yusupov, Vladimir I.; Sviridov, Alexander P.; Zhigarkov, Vyacheslav S.; Shubnyy, Andrey G.; Vorobieva, Nataliya N.; Churbanov, Semyon N.; Minaev, Nikita V.; Timashev, Peter S.; Rochev, Yury A.; Bagratashvili, Victor N.

2018-04-01

Light field intensity distribution in three-dimensional polylactide scaffolds after irradiation with low-intensity light from one side of the samples has been determined in the visible and near-infrared regions of the spectrum. Two different types of scaffolds manufactured by the methods of supercritical fluid foaming and surface selective laser sintering have been investigated. The problem is solved by numerical calculation according to the Monte Carlo method involving experimentally obtained information about effective optical parameters of the scaffold material. Information about intensity distribution of the incident light in the matrix volume is needed to assess the radiation level for the scaffold cells after photobiostimulation. It has been shown that the formation of the light field in case of strongly scattering media, such as polylactide scaffolds, is determined by anisotropy g and the scattering coefficient μs.

Multimodal diagnosis and visualisation of oncologic pathologies

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

Zakharov, V P; Bratchenko, I A; Myakinin, O O

2014-08-31

The combined application of optical coherence tomography, Raman and autofluorescence spectroscopy of biotissues for the analysis of human malignant neoplasms is demonstrated. Rapid investigation of vast biotissue regions (at the scale of entire organs) is possible using the autofluorescence response. After selection of possible zones of pathologies one can visualise the neoplasm topology in the zone of interest with micron precision by using optical coherence tomography. In the case of suspecting the malignancy the analysis of the biotissue Raman spectrum is carried out that allows identification of the neoplasm type with the sensitivity and specificity ∼85%. An experimental scheme ismore » proposed with the combined use of the abovementioned methods, which is a prototype of the medical system for complex analysis of neoplasms. (laser biophotonics)« less

A versatile optical microscope for time-dependent single-molecule and single-particle spectroscopy.

PubMed

Li, Hao; Yang, Haw

2018-03-28

This work reports the design and implementation of a multi-function optical microscope for time-dependent spectroscopy on single molecules and single nanoparticles. It integrates the now-routine single-object measurements into one standalone platform so that no reconfiguration is needed when switching between different types of sample or spectroscopy modes. The illumination modes include evanescent field through total internal reflection, dark-field illumination, and epi-excitation onto a diffraction-limited spot suitable for confocal detection. The detection modes include spectrally resolved line imaging, wide-field imaging with dual-color capability, and two-color single-element photon-counting detection. The switch between different spectroscopy and data acquisition modes is fully automated and executed through computer programming. The capability of this microscope is demonstrated through selected proof-of-principle experiments.

The ESA RADGLASS activity: a radiation study of non rad-hard glasses

NASA Astrophysics Data System (ADS)

Manolis, Ilias; Bézy, Jean-Loup; Costantino, Alessandra; Vink, Ramon; Deep, Atul; Ahmad, Munadi; Amorim, Emmanuel; Miranda, Micael D.; Meynart, Roland

2015-10-01

Only a small set of radiation hardened optical glasses are currently offered in the market, thus drastically limiting the optical design choices available to the engineers at the early phases of an instrument development. Furthermore, availability of those glasses cannot be easily guaranteed for the long term horizon of future space instrument developments. Radiation tests on conventional glasses on the other hand have shown significant sensitivity to high radiation levels but such levels are not necessarily representative of typical low Earth (LEO) orbits. We have conducted irradiation campaigns on several different types of conventional, non-radiation hard glasses, selected from the wider pool of the Schott "new" arsenic and lead free series (N-*) and characterized their spectral transmission properties before and after ionizing dose deposition. We report our first findings here.

Optical Trap Loading of Dielectric Microparticles In Air.

PubMed

Park, Haesung; LeBrun, Thomas W

2017-02-05

We demonstrate a method to trap a selected dielectric microparticle in air using radiation pressure from a single-beam gradient optical trap. Randomly scattered dielectric microparticles adhered to a glass substrate are momentarily detached using ultrasonic vibrations generated by a piezoelectric transducer (PZT). Then, the optical beam focused on a selected particle lifts it up to the optical trap while the vibrationally excited microparticles fall back to the substrate. A particle may be trapped at the nominal focus of the trapping beam or at a position above the focus (referred to here as the levitation position) where gravity provides the restoring force. After the measurement, the trapped particle can be placed at a desired position on the substrate in a controlled manner. In this protocol, an experimental procedure for selective optical trap loading in air is outlined. First, the experimental setup is briefly introduced. Second, the design and fabrication of a PZT holder and a sample enclosure are illustrated in detail. The optical trap loading of a selected microparticle is then demonstrated with step-by-step instructions including sample preparation, launching into the trap, and use of electrostatic force to excite particle motion in the trap and measure charge. Finally, we present recorded particle trajectories of Brownian and ballistic motions of a trapped microparticle in air. These trajectories can be used to measure stiffness or to verify optical alignment through time domain and frequency domain analysis. Selective trap loading enables optical tweezers to track a particle and its changes over repeated trap loadings in a reversible manner, thereby enabling studies of particle-surface interaction.

AEGIS: Demographics of X-ray and Optically Selected Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

Yan, Renbin; Ho, Luis C.; Newman, Jeffrey A.; Coil, Alison L.; Willmer, Christopher N. A.; Laird, Elise S.; Georgakakis, Antonis; Aird, James; Barmby, Pauline; Bundy, Kevin; Cooper, Michael C.; Davis, Marc; Faber, S. M.; Fang, Taotao; Griffith, Roger L.; Koekemoer, Anton M.; Koo, David C.; Nandra, Kirpal; Park, Shinae Q.; Sarajedini, Vicki L.; Weiner, Benjamin J.; Willner, S. P.

2011-02-01

We develop a new diagnostic method to classify galaxies into active galactic nucleus (AGN) hosts, star-forming galaxies, and absorption-dominated galaxies by combining the [O III]/Hβ ratio with rest-frame U - B color. This can be used to robustly select AGNs in galaxy samples at intermediate redshifts (z < 1). We compare the result of this optical AGN selection with X-ray selection using a sample of 3150 galaxies with 0.3 < z < 0.8 and I AB < 22, selected from the DEEP2 Galaxy Redshift Survey and the All-wavelength Extended Groth Strip International Survey. Among the 146 X-ray sources in this sample, 58% are classified optically as emission-line AGNs, the rest as star-forming galaxies or absorption-dominated galaxies. The latter are also known as "X-ray bright, optically normal galaxies" (XBONGs). Analysis of the relationship between optical emission lines and X-ray properties shows that the completeness of optical AGN selection suffers from dependence on the star formation rate and the quality of observed spectra. It also shows that XBONGs do not appear to be a physically distinct population from other X-ray detected, emission-line AGNs. On the other hand, X-ray AGN selection also has strong bias. About 2/3 of all emission-line AGNs at L bol > 1044 erg s-1 in our sample are not detected in our 200 ks Chandra images, most likely due to moderate or heavy absorption by gas near the AGN. The 2-7 keV detection rate of Seyfert 2s at z ~ 0.6 suggests that their column density distribution and Compton-thick fraction are similar to that of local Seyferts. Multiple sample selection techniques are needed to obtain as complete a sample as possible.

Single-crystalline oxide films of the Al2O3-Y2O3-R2O3 system as optical sensors of various types of ionizing radiation: significant advantages over volume analogs

NASA Astrophysics Data System (ADS)

Zorenko, Yuri V.; Batenchuk, M.; Gorbenco, V.; Pashkovsky, M.

1997-02-01

This investigation is dedicated to studying of peculiarities of luminescent properties of the single crystalline films (SCF) of Al2O3-Y2O3-R2O3 oxide system with alpha-Al2O3 and garnet structure, which are used as various types of ionizing radiation luminescent detectors. These peculiarities define the number of nontrivial advantages over their volume analogues. It is shown that SCF are characterized by the low concentrations of vacancy type defects and substituent defects, and the high concentration of Pb ion as dopant. This allows us to substantially increase the spatial resolution and selectivity of cathodoluminophores on the base of these compounds.

A Cre Mouse Line for Probing Irradiance- and Direction-Encoding Retinal Networks

PubMed Central

Sabbah, Shai

2017-01-01

Abstract Cell type-specific Cre driver lines have revolutionized the analysis of retinal cell types and circuits. We show that the transgenic mouse Rbp4-Cre selectively labels several retinal neuronal types relevant to the encoding of absolute light intensity (irradiance) and visual motion. In the ganglion cell layer (GCL), most marked cells are wide-field spiking polyaxonal amacrine cells (ACs) with sustained irradiance-encoding ON responses that persist during chemical synaptic blockade. Their arbors spread about 1 mm across the retina and are restricted to the inner half of the ON sublamina of the inner plexiform layer (IPL). There, they costratify with dendrites of M2 intrinsically photosensitive retinal ganglion cells (ipRGCs), to which they are tracer coupled. We propose that synaptically driven and intrinsic photocurrents of M2 cells pass through gap junctions to drive AC light responses. Also marked in this mouse are two types of RGCs. R-cells have a bistratified dendritic arbor, weak directional tuning, and irradiance-encoding ON responses. However, they also receive excitatory OFF input, revealed during ON-channel blockade. Serial blockface electron microscopic (SBEM) reconstruction confirms OFF bipolar input, and reveals that some OFF input derives from a novel type of OFF bipolar cell (BC). R-cells innervate specific layers of the dorsal lateral geniculate nucleus (dLGN) and superior colliculus (SC). The other marked RGC type (RDS) is bistratified, transient, and ON-OFF direction selective (DS). It apparently innervates the nucleus of the optic tract (NOT). The Rbp4-Cre mouse will be valuable for targeting these cell types for further study and for selectively manipulating them for circuit analysis. PMID:28466070

Post-processing of adaptive optics images based on frame selection and multi-frame blind deconvolution

NASA Astrophysics Data System (ADS)

Tian, Yu; Rao, Changhui; Wei, Kai

2008-07-01

The adaptive optics can only partially compensate the image blurred by atmospheric turbulence due to the observing condition and hardware restriction. A post-processing method based on frame selection and multi-frames blind deconvolution to improve images partially corrected by adaptive optics is proposed. The appropriate frames which are suitable for blind deconvolution from the recorded AO close-loop frames series are selected by the frame selection technique and then do the multi-frame blind deconvolution. There is no priori knowledge except for the positive constraint in blind deconvolution. It is benefit for the use of multi-frame images to improve the stability and convergence of the blind deconvolution algorithm. The method had been applied in the image restoration of celestial bodies which were observed by 1.2m telescope equipped with 61-element adaptive optical system at Yunnan Observatory. The results show that the method can effectively improve the images partially corrected by adaptive optics.

Sensitive And Selective Chemical Sensor With Nanostructured Surfaces.

DOEpatents

Pipino, Andrew C. R.

2003-02-04

A chemical sensor is provided which includes an optical resonator including a nanostructured surface comprising a plurality of nanoparticles bound to one or more surfaces of the resonator. The nanoparticles provide optical absorption and the sensor further comprises a detector for detecting the optical absorption of the nanoparticles or their environment. In particular, a selective chemical interaction is provided which modifies the optical absorption of the nanoparticles or their environment, and an analyte is detected based on the modified optical absorption. A light pulse is generated which enters the resonator to interrogate the modified optical absorption and the exiting light pulse is detected by the detector.

Sighting optics including an optical element having a first focal length and a second focal length

DOEpatents

Crandall, David Lynn [Idaho Falls, ID

2011-08-01

One embodiment of sighting optics according to the teachings provided herein may include a front sight and a rear sight positioned in spaced-apart relation. The rear sight includes an optical element having a first focal length and a second focal length. The first focal length is selected so that it is about equal to a distance separating the optical element and the front sight and the second focal length is selected so that it is about equal to a target distance. The optical element thus brings into simultaneous focus, for a user, images of the front sight and the target.

Sighting optics including an optical element having a first focal length and a second focal length and methods for sighting

DOEpatents

Crandall, David Lynn

2011-08-16

Sighting optics include a front sight and a rear sight positioned in a spaced-apart relation. The rear sight includes an optical element having a first focal length and a second focal length. The first focal length is selected so that it is about equal to a distance separating the optical element and the front sight and the second focal length is selected so that it is about equal to a target distance. The optical element thus brings into simultaneous focus for a user images of the front sight and the target.

Analysis of behavior of focusing error signals generated by astigmatic method when a focused spot moves beyond the radius of a land-groove-type optical disk

NASA Astrophysics Data System (ADS)

Shinoda, Masahisa; Nakatani, Hidehiko; Nakai, Kenya; Ohmaki, Masayuki

2015-09-01

We theoretically calculate behaviors of focusing error signals generated by an astigmatic method in a land-groove-type optical disk. The focusing error signal from the land does not coincide with that from the groove. This behavior is enhanced when a focused spot of an optical pickup moves beyond the radius of the optical disk. A gain difference between the slope sensitivities of focusing error signals from the land and the groove is an important factor with respect to stable focusing servo control. In our calculation, the format of digital versatile disc-random access memory (DVD-RAM) is adopted as the land-groove-type optical disk model, and the dependences of the gain difference on various factors are investigated. The gain difference strongly depends on the optical intensity distribution of the laser beam in the optical pickup. The calculation method and results in this paper will be reflected in newly developed land-groove-type optical disks.

Analysis of the selected optical parameters of filters protecting against hazardous infrared radiation.

PubMed

Gralewicz, Grzegorz; Owczarek, Grzegorz

2016-09-01

The paper analyses the selected optical parameters of protective optic filters used for protection of the eyes against hazardous radiation within the visible (VIS) and near infrared (NIR) spectrum range. The indexes characterizing transmission and reflection of optic radiation incident on the filter are compared. As it follows from the completed analysis, the newly developed interference filters provide more effective blocking of infrared radiation in comparison with the currently used protective filters.

The XMM-Newton bright serendipitous survey. Identification and optical spectral properties

NASA Astrophysics Data System (ADS)

Caccianiga, A.; Severgnini, P.; Della Ceca, R.; Maccacaro, T.; Cocchia, F.; Barcons, X.; Carrera, F. J.; Matute, I.; McMahon, R. G.; Page, M. J.; Pietsch, W.; Sbarufatti, B.; Schwope, A.; Tedds, J. A.; Watson, M. G.

2008-01-01

Aims:We present the optical classification and redshift of 348 X-ray selected sources from the XMM-Newton Bright Serendipitous Survey (XBS), which contains a total of 400 objects (identification level = 87%). About 240 are new identifications. In particular, we discuss in detail the classification criteria adopted for the active galactic nuclei (AGNs) population. Methods: By means of systematic spectroscopic campaigns using various telescopes and through the literature search, we have collected an optical spectrum for the large majority of the sources in the XBS survey and applied a well-defined classification “flow chart”. Results: We find that the AGNs represent the most numerous population at the flux limit of the XBS survey (~10-13 erg cm-2 s-1) constituting 80% of the XBS sources selected in the 0.5-4.5 keV energy band and 95% of the “hard” (4.5-7.5 keV) selected objects. Galactic sources populate the 0.5-4.5 keV sample significantly (17%) and only marginally (3%) the 4.5-7.5 keV sample. The remaining sources in both samples are clusters/groups of galaxies and normal galaxies (i.e. probably not powered by an AGN). Furthermore, the percentage of type 2 AGNs (i.e. optically absorbed AGNs with A_V>2 mag) dramatically increases going from the 0.5-4.5 keV sample (f=NAGN 2/N_AGN=7%) to the 4.5-7.5 keV sample (f=32%). We finally propose two simple diagnostic plots that can be easily used to obtain the spectral classification for relatively low-redshift AGNs even if the quality of the spectrum is not good. Based on observations collected at the Telescopio Nazionale Galileo (TNG) and at the European Southern Observatory (ESO) and on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and the USA (NASA). Table 3 is only available in electronic form at http://www.aanda.org

Non-Dispersive Infrared Sensor for Online Condition Monitoring of Gearbox Oil.

PubMed

Rauscher, Markus S; Tremmel, Anton J; Schardt, Michael; Koch, Alexander W

2017-02-18

The condition of lubricating oil used in automotive and industrial gearboxes must be controlled in order to guarantee optimum performance and prevent damage to machinery parts. In normal practice, this is done by regular oil change intervals and routine laboratory analysis, both of which involve considerable operating costs. In this paper, we present a compact and robust optical sensor that can be installed in the lubrication circuit to provide quasi-continuous information about the condition of the oil. The measuring principle is based on non-dispersive infrared spectroscopy. The implemented sensor setup consists of an optical measurement cell, two thin-film infrared emitters, and two four-channel pyroelectric detectors equipped with optical bandpass filters. We present a method based on multivariate partial least squares regression to select appropriate optical bandpass filters for monitoring the oxidation, water content, and acid number of the oil. We perform a ray tracing analysis to analyze and correct the influence of the light path in the optical setup on the optical parameters of the bandpass filters. The measurement values acquired with the sensor for three different gearbox oil types show high correlation with laboratory reference data for the oxidation, water content, and acid number. The presented sensor can thus be a useful supplementary tool for the online condition monitoring of lubricants when integrated into a gearbox oil circuit.

Ultrafast Silicon Photonics with Visible to Mid-Infrared Pumping of Silicon Nanocrystals.

PubMed

Diroll, Benjamin T; Schramke, Katelyn S; Guo, Peijun; Kortshagen, Uwe R; Schaller, Richard D

2017-10-11

Dynamic optical control of infrared (IR) transparency and refractive index is achieved using boron-doped silicon nanocrystals excited with mid-IR optical pulses. Unlike previous silicon-based optical switches, large changes in transmittance are achieved without a fabricated structure by exploiting strong light coupling of the localized surface plasmon resonance (LSPR) produced from free holes of p-type silicon nanocrystals. The choice of optical excitation wavelength allows for selectivity between hole heating and carrier generation through intraband or interband photoexcitation, respectively. Mid-IR optical pumping heats the free holes of p-Si nanocrystals to effective temperatures greater than 3500 K. Increases of the hole effective mass at high effective hole temperatures lead to a subpicosecond change of the dielectric function, resulting in a redshift of the LSPR, modulating mid-IR transmission by as much as 27%, and increasing the index of refraction by more than 0.1 in the mid-IR. Low hole heat capacity dictates subpicosecond hole cooling, substantially faster than carrier recombination, and negligible heating of the Si lattice, permitting mid-IR optical switching at terahertz repetition frequencies. Further, the energetic distribution of holes at high effective temperatures partially reverses the Burstein-Moss effect, permitting the modulation of transmittance at telecommunications wavelengths. The results presented here show that doped silicon, particularly in micro- or nanostructures, is a promising dynamic metamaterial for ultrafast IR photonics.

Non-Dispersive Infrared Sensor for Online Condition Monitoring of Gearbox Oil

PubMed Central

Rauscher, Markus S.; Tremmel, Anton J.; Schardt, Michael; Koch, Alexander W.

2017-01-01

The condition of lubricating oil used in automotive and industrial gearboxes must be controlled in order to guarantee optimum performance and prevent damage to machinery parts. In normal practice, this is done by regular oil change intervals and routine laboratory analysis, both of which involve considerable operating costs. In this paper, we present a compact and robust optical sensor that can be installed in the lubrication circuit to provide quasi-continuous information about the condition of the oil. The measuring principle is based on non-dispersive infrared spectroscopy. The implemented sensor setup consists of an optical measurement cell, two thin-film infrared emitters, and two four-channel pyroelectric detectors equipped with optical bandpass filters. We present a method based on multivariate partial least squares regression to select appropriate optical bandpass filters for monitoring the oxidation, water content, and acid number of the oil. We perform a ray tracing analysis to analyze and correct the influence of the light path in the optical setup on the optical parameters of the bandpass filters. The measurement values acquired with the sensor for three different gearbox oil types show high correlation with laboratory reference data for the oxidation, water content, and acid number. The presented sensor can thus be a useful supplementary tool for the online condition monitoring of lubricants when integrated into a gearbox oil circuit. PMID:28218701

Ultrafast Silicon Photonics with Visible to Mid-Infrared Pumping of Silicon Nanocrystals

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

Diroll, Benjamin T.; Schramke, Katelyn S.; Guo, Peijun

Dynamic optical control of infrared (IR) transparency and refractive index is achieved using boron-doped silicon nanocrystals excited with mid-IR optical pulses. Also, unlike previous silicon-based optical switches, large changes in transmittance are achieved without a fabricated structure by exploiting strong light coupling of the localized surface plasmon resonance (LSPR) produced from free holes of p-type silicon nanocrystals. The choice of optical excitation wavelength allows selectivity between hole heating and carrier generation through intraband or interband photoexcitation, respectively. Mid-IR optical pumping heats the free holes of p-Si nanocrystals to effective temperatures greater than 3500 K. Increases of the hole effective massmore » at high effective hole temperatures lead to a sub-picosecond change of the dielectric function resulting in a redshift of the LSPR, modulating mid-IR transmission by as much as 27% and increasing the index of refraction by more than 0.1 in the mid-IR. Low hole heat capacity dictates sub-picosecond hole cooling, substantially faster than carrier recombination, and negligible heating of the Si lattice, permitting mid-IR optical switching at terahertz repetition frequencies. Further, the energetic distribution of holes at high effective temperatures partially reverses the Burstein-Moss effect, permitting modulation of transmittance at telecommunications wavelengths. Lastly, the results presented here show that doped silicon, particularly in micro- or nanostructures, is a promising dynamic metamaterial for ultrafast IR photonics.« less

Ultrafast Silicon Photonics with Visible to Mid-Infrared Pumping of Silicon Nanocrystals

DOE PAGES

Diroll, Benjamin T.; Schramke, Katelyn S.; Guo, Peijun; ...

2017-09-11

Dynamic optical control of infrared (IR) transparency and refractive index is achieved using boron-doped silicon nanocrystals excited with mid-IR optical pulses. Also, unlike previous silicon-based optical switches, large changes in transmittance are achieved without a fabricated structure by exploiting strong light coupling of the localized surface plasmon resonance (LSPR) produced from free holes of p-type silicon nanocrystals. The choice of optical excitation wavelength allows selectivity between hole heating and carrier generation through intraband or interband photoexcitation, respectively. Mid-IR optical pumping heats the free holes of p-Si nanocrystals to effective temperatures greater than 3500 K. Increases of the hole effective massmore » at high effective hole temperatures lead to a sub-picosecond change of the dielectric function resulting in a redshift of the LSPR, modulating mid-IR transmission by as much as 27% and increasing the index of refraction by more than 0.1 in the mid-IR. Low hole heat capacity dictates sub-picosecond hole cooling, substantially faster than carrier recombination, and negligible heating of the Si lattice, permitting mid-IR optical switching at terahertz repetition frequencies. Further, the energetic distribution of holes at high effective temperatures partially reverses the Burstein-Moss effect, permitting modulation of transmittance at telecommunications wavelengths. Lastly, the results presented here show that doped silicon, particularly in micro- or nanostructures, is a promising dynamic metamaterial for ultrafast IR photonics.« less

Polarization Dependence Suppression of Optical Fiber Grating Sensor in a π-Shifted Sagnac Loop Interferometer

PubMed Central

Son, Jaebum; Lee, Min-Kyoung; Jeong, Myung Yung; Kim, Chang-Seok

2010-01-01

In the sensing applications of optical fiber grating, it is necessary to reduce the transmission-type polarization dependence to isolate the sensing parameter. It is experimentally shown that the polarization-dependent spectrum of acousto-optic long-period fiber grating sensors can be suppressed in the transmission port of a π-shifted Sagnac loop interferometer. General expressions for the transmittance and reflectance are derived for transmission-type, reflection-type, and partially reflecting/transmitting-type polarization-dependent optical devices. The compensation of polarization dependence through the counter propagation in the Sagnac loop interferometer is quantitatively measured for a commercial in-line polarizer and an acousto-optic long-period fiber grating sensor. PMID:22399884

The optical blocking filter for the ATHENA wide field imager: ongoing activities towards the conceptual design

NASA Astrophysics Data System (ADS)

Barbera, M.; Branduardi-Raymont, G.; Collura, A.; Comastri, A.; Eder, J.; Kamisiński, T.; Lo Cicero, U.; Meidinger, N.; Mineo, T.; Molendi, S.; Parodi, G.; Pilch, A.; Piro, L.; Rataj, M.; Rauw, G.; Sciortino, L.; Sciortino, S.; Wawer, P.

2015-08-01

ATHENA is the L2 mission selected by ESA to pursue the science theme "Hot and Energetic Universe" (launch scheduled in 2028). One of the key instruments of ATHENA is the Wide Field Imager (WFI) which will provide imaging in the 0.1-15 keV band over a 40'x40' large field of view, together with spectrally and time-resolved photon counting. The WFI camera, based on arrays of DEPFET active pixel sensors, is also sensitive to UV/Vis photons. Optically generated electron-hole pairs may degrade the spectral resolution as well as change the energy scale by introducing a signal offset. For this reason, the use of an X-ray transparent optical blocking filter is needed to allow the observation of all type of X-ray sources that present a UV/Visible bright counterpart. In this paper, we describe the main activities that we are carrying on for the conceptual design of the optical blocking filter, that will be mounted on the filter wheel, in order to satisfy the scientific requirements on optical load from bright UV/Vis astrophysical source, to maximize the X-ray transmission, and to withstand the severe acoustic and vibration loads foreseen during launch.

Characteristics of strain-sensitive photonic crystal cavities in a flexible substrate.

PubMed

No, You-Shin; Choi, Jae-Hyuck; Kim, Kyoung-Ho; Park, Hong-Gyu

2016-11-14

High-index semiconductor photonic crystal (PhC) cavities in a flexible substrate support strong and tunable optical resonances that can be used for highly sensitive and spatially localized detection of mechanical deformations in physical systems. Here, we report theoretical studies and fundamental understandings of resonant behavior of an optical mode excited in strain-sensitive rod-type PhC cavities consisting of high-index dielectric nanorods embedded in a low-index flexible polymer substrate. Using the three-dimensional finite-difference time-domain simulation method, we calculated two-dimensional transverse-electric-like photonic band diagrams and the three-dimensional dispersion surfaces near the first Γ-point band edge of unidirectionally strained PhCs. A broken rotational symmetry in the PhCs modifies the photonic band structures and results in the asymmetric distributions and different levels of changes in normalized frequencies near the first Γ-point band edge in the reciprocal space, which consequently reveals strain-dependent directional optical losses and selected emission patterns. The calculated electric fields, resonant wavelengths, and quality factors of the band-edge modes in the strained PhCs show an excellent agreement with the results of qualitative analysis of modified dispersion surfaces. Furthermore, polarization-resolved time-averaged Poynting vectors exhibit characteristic dipole-like emission patterns with preferentially selected linear polarizations, originating from the asymmetric band structures in the strained PhCs.

The system spatial-frequency filtering of birefringence images of human blood layers

NASA Astrophysics Data System (ADS)

Ushenko, A. G.; Boychuk, T. M.; Mincer, O. P.; Angelsky, P. O.; Bodnar, N. B.; Oleinichenko, B. P.; Bizer, L. I.

2013-09-01

Among various opticophysical methods [1 - 3] of diagnosing the structure and properties of the optical anisotropic component of various biological objects a specific trend has been singled out - multidimensional laser polarimetry of microscopic images of the biological tissues with the following statistic, correlative and fractal analysis of the coordinate distributions of the azimuths and ellipticity of polarization in approximating of linear birefringence polycrystalline protein networks [4 - 10]. At the same time, in most cases, experimental obtaining of tissue sample is a traumatic biopsy operation. In addition, the mechanisms of transformation of the state of polarization of laser radiation by means of the opticoanisotropic biological structures are more varied (optical dichroism, circular birefringence). Hereat, real polycrystalline networks can be formed by different types, both in size and optical properties of biological crystals. Finally, much more accessible for an experimental investigation are biological fluids such as blood, bile, urine, and others. Thus, further progress of laser polarimetry can be associated with the development of new methods of analysis and processing (selection) of polarization- heterogeneous images of biological tissues and fluids, taking into account a wider set of mechanisms anisotropic mechanisms. Our research is aimed at developing experimental method of the Fourier polarimetry and a spatialfrequency selection for distributions of the azimuth and the ellipticity polarization of blood plasma laser images with a view of diagnosing prostate cancer.

Optical Properties of the DIRC Fused Silica Radiator

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

Convery, Mark R

2003-04-15

The DIRC detector is successfully operating as the hadronic particle identification system for the BaBar experiment at SLAC. The production of its Cherenkov radiator required much effort in practice, both in manufacture and conception, which in turn required a large number of R&D measurements. One of the major outcomes of this R&D work was an understanding of methods to select radiation hard and optically uniform fused silica material. Others included measurement of the wavelength dependency of the internal reflection coefficient, and its sensitivity to the surface pollution, selection of the radiator support, selection of good optical glue, etc. This notemore » summarizes the optical R&D test results.« less

Linearization of Positional Response Curve of a Fiber-optic Displacement Sensor

NASA Astrophysics Data System (ADS)

Babaev, O. G.; Matyunin, S. A.; Paranin, V. D.

2018-01-01

Currently, the creation of optical measuring instruments and sensors for measuring linear displacement is one of the most relevant problems in the area of instrumentation. Fiber-optic contactless sensors based on the magneto-optical effect are of special interest. They are essentially contactless, non-electrical and have a closed optical channel not subject to contamination. The main problem of this type of sensors is the non-linearity of their positional response curve due to the hyperbolic nature of the magnetic field intensity variation induced by moving the magnetic source mounted on the controlled object relative to the sensing element. This paper discusses an algorithmic method of linearizing the positional response curve of fiber-optic displacement sensors in any selected range of the displacements to be measured. The method is divided into two stages: 1 - definition of the calibration function, 2 - measurement and linearization of the positional response curve (including its temperature stabilization). The algorithm under consideration significantly reduces the number of points of the calibration function, which is essential for the calibration of temperature dependence, due to the use of the points that randomly deviate from the grid points with uniform spacing. Subsequent interpolation of the deviating points and piecewise linear-plane approximation of the calibration function reduces the microcontroller storage capacity for storing the calibration function and the time required to process the measurement results. The paper also presents experimental results of testing real samples of fiber-optic displacement sensors.

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.

Herschel-ATLAS: Dusty early-type galaxies

NASA Astrophysics Data System (ADS)

Rowlands, K.; Dunne, L.; Maddox, S.

2015-03-01

Early-type galaxies (ETGs) are thought to be devoid of dust and star-formation, having formed most of their stars at early epochs. We present the detection of the dustiest ETGs in a large-area blind submillimetre survey with Herschel (H-ATLAS, Eales et al. 2010), where the lack of pre-selection in other bands makes it the first unbiased survey for cold dust in ETGs. The parent sample of 1087 H-ATLAS galaxies in this study have a >= 5σ detection at 250μm, a reliable optical counterpart to the submillimetre source (Smith et al. 2011) and a spectroscopic redshift from the GAMA survey (Driver et al. 2011). Additionally, we construct a control sample of 1052 optically selected galaxies undetected at 250μm and matched in stellar mass to the H-ATLAS parent sample to eliminate selection effects. ETGs were selected from both samples via visual classifications using SDSS images. Further details can be found in Rowlands et al. (2012). Physical parameters are derived for each galaxy using the multiwavelength spectral energy distribution (SED) fitting code of da Cunha, Charlot and Elbaz (2008), Smith et al. 2012, using an energy balance argument. We investigate the differences between the dusty ETGs and the general ETG population, and find that the H-ATLAS ETGs are more than an order of magnitude dustier than the control ETGs. The mean dust mass of the 42 H-ATLAS ETGs is 5.5 × 107M⊙ (comparable to the dust mass of spirals in our sample), whereas the dust mass of the 233 control ETGs inferred from stacking at optical positions on the 250μm map is (0.8 - 4.0) × 106M⊙ for 25-15 K dust. The average star-formation rate of the H-ATLAS ETGs is 1.0 dex higher than that of control ETGs, and the mean r-band light-weighted age of the H-ATLAS ETGs is 1.8 Gyr younger than the control ETGs. The rest-frame NUV - r colours of the H-ATLAS ETGs are 1.0 magnitudes bluer than the control ETGs, and some ETGs may be transitioning from the blue cloud to the red sequence. Some H-ATLAS ETGs show signs of morphological disturbance and may have undergone recent rejuvenation of their ISM via gas and dust delivered by mergers. It is found that late-type stars cannot produce enough dust to account for that observed in the H-ATLAS ETGs. This indicates that either an external source of dust from mergers is required, a substantial amount of dust grain growth must occur in the ISM, or dust destruction by hot X-ray gas is less efficient than predicted.

Interferometric phase locking of two electronic oscillators with a cascade electro-optic modulator

NASA Astrophysics Data System (ADS)

Chao, C. H.; Chien, P. Y.; Chang, L. W.; Juang, F. Y.; Hsia, C. H.; Chang, C. C.

1993-01-01

An optical-type electrical phase-locked-loop system based on a cascade electro-optic modulator has been demonstrated. By using this technique, a set of optical-type phase detectors, operating at any harmonic frequencies of two applied phase-modulation signals, has been implemented.

Micro-optical fiber probe for use in an intravascular Raman endoscope.

PubMed

Komachi, Yuichi; Sato, Hidetoshi; Aizawa, Katsuo; Tashiro, Hideo

2005-08-01

We believe that we have developed the narrowest optical-fiber Raman probe ever reported, 600 microm in total diameter, that can be inserted into coronary arteries. The selection of suitable optical fibers, filters, and a processing method is discussed. Custom-made filters attached to the front end of a probe eliminate the background Raman signals of the optical fiber itself. The experimental evaluation of various optical fibers is carried out for the selection of suitable fibers. Measurement of the Raman spectra of an atherosclerotic lesion of a rabbit artery in vitro demonstrates the excellent performance of the micro-Raman probe.

The most luminous type 2 Active Galactic Nuclei of the Swift/ BAT catalog : Are they different?

NASA Astrophysics Data System (ADS)

Baer, Rudolf Erik; Oh, Kyuseok; Koss, Michael; Wong, Ivy; Schawinski, Kevin

2018-01-01

We present an analysis of the most luminous obscured AGN of the Swift/BAT 70 month catalog, which is based on an all-sky survey in the 14 – 195 keV energy range. This survey identified 838 AGN. Excluding Blazars and AGN close ( |gb| < 6o ) to the Galactic plane we select a sample of the 30 most luminous type 2 AGN. We analyze their emission line properties in the optical and infrared range and their radio properties using data in the 150 MHz to 22 GHz range. We obtained their black hole masses from the Swift/ BAT 70 month catalog and from a specific observation campaign in order to analyze the relationship of their luminosity to black hole mass and their Eddington ratios. We discuss whether these most luminous type 2 AGN have common characteristics, which differentiate them from all the type 2 AGN in the 70 month catalog.

Merging Features and Optical-Near Infrared Color Gradients of Early-type Galaxies

NASA Astrophysics Data System (ADS)

Kim, Duho; Im, M.

2012-01-01

It has been suggested that merging plays an important role in the formation and the evolution of early-type galaxies (ETGs). Optical-NIR color gradients of ETGs in high density environments are found to be less steep than those of ETGs in low density environments, hinting frequent merger activities in ETGs in high density environments. In order to examine if the flat color gradients are the result of dry mergers, we studied the relations between merging features, color gradient, and environments of 198 low redshift ETGs selected from Sloan Digital Sky Survey (SDSS) Stripe82. Near Infrared (NIR) images are taken from UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS). Color(r-K) gradients of ETGs with tidal features are a little flatter than relaxed ETGs, but not significant. We found that massive (>1011.3 M⊙) relaxed ETGs have 2.5 times less scattered color gradients than less massive ETGs. The less scattered color gradients of massive ETGs could be evidence of dry merger processes in the evolution of massive ETGs. We found no relation between color gradients of ETGs and their environments.

A Survey for Hα Emission from Late L Dwarfs and T Dwarfs

NASA Astrophysics Data System (ADS)

Pineda, J. Sebastian; Hallinan, Gregg; Kirkpatrick, J. Davy; Cotter, Garret; Kao, Melodie M.; Mooley, Kunal

2016-07-01

Recently, studies of brown dwarfs have demonstrated that they possess strong magnetic fields and have the potential to produce radio and optical auroral emissions powered by magnetospheric currents. This emission provides the only window on magnetic fields in the coolest brown dwarfs and identifying additional benchmark objects is key to constraining dynamo theory in this regime. To this end, we conducted a new red optical (6300-9700 Å) survey with the Keck telescopes looking for Hα emission from a sample of late L dwarfs and T dwarfs. Our survey gathered optical spectra for 29 targets, 18 of which did not have previous optical spectra in the literature, greatly expanding the number of moderate-resolution (R ˜ 2000) spectra available at these spectral types. Combining our sample with previous surveys, we confirm an Hα detection rate of 9.2±{}2.13.5% for L and T dwarfs in the optical spectral range of L4-T8. This detection rate is consistent with the recently measured detection rate for auroral radio emission from Kao et al., suggesting that geometrical selection effects due to the beaming of the radio emission are small or absent. We also provide the first detection of Hα emission from 2MASS 0036+1821, previously notable as the only electron cyclotron maser radio source without a confirmed detection of Hα emission. Finally, we also establish optical standards for spectral types T3 and T4, filling in the previous gap between T2 and T5. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

Optical selection and collection of DNA fragments

DOEpatents

Roslaniec, Mary C.; Martin, John C.; Jett, James H.; Cram, L. Scott

1998-01-01

Optical selection and collection of DNA fragments. The present invention includes the optical selection and collection of large (>.mu.g) quantities of clonable, chromosome-specific DNA from a sample of chromosomes. Chromosome selection is based on selective, irreversible photoinactivation of unwanted chromosomal DNA. Although more general procedures may be envisioned, the invention is demonstrated by processing chromosomes in a conventional flow cytometry apparatus, but where no droplets are generated. All chromosomes in the sample are first stained with at least one fluorescent analytic dye and bonded to a photochemically active species which can render chromosomal DNA unclonable if activated. After passing through analyzing light beam(s), unwanted chromosomes are irradiated using light which is absorbed by the photochemically active species, thereby causing photoinactivation. As desired chromosomes pass this photoinactivation point, the inactivating light source is deflected by an optical modulator; hence, desired chromosomes are not photoinactivated and remain clonable. The selection and photoinactivation processes take place on a microsecond timescale. By eliminating droplet formation, chromosome selection rates 50 times greater than those possible with conventional chromosome sorters may be obtained. Thus, usable quantities of clonable DNA from any source thereof may be collected.

Fetal muscle-type nicotinic acetylcholine receptor activation in TE-671 cells and inhibition of fetal movement in a day 40 pregnant goat model by optical isomers of the piperidine alkaloid coniine.

PubMed

Green, Benedict T; Lee, Stephen T; Welch, Kevin D; Pfister, James A; Panter, Kip E

2013-01-01

Coniine is an optically active toxic piperidine alkaloid and nicotinic acetylcholine receptor (nAChR) agonist found in poison hemlock (Conium maculatum L.). Coniine teratogenicity is hypothesized to be attributable to the binding, activation, and prolonged desensitization of fetal muscle-type nAChR, which results in the complete inhibition of fetal movement. However, pharmacological evidence of coniine actions at fetal muscle-type nAChR is lacking. The present study compared (-)-coniine, (+)-coniine, and nicotine for the ability to inhibit fetal movement in a day 40 pregnant goat model and in TE-671 cells that express fetal muscle-type nAChR. Furthermore, α-conotoxins (CTx) EI and GI were used to antagonize the actions of (+)- and (-)-coniine in TE-671 cells. (-)-Coniine was more effective at eliciting electrical changes in TE-671 cells and inhibiting fetal movement than was (+)-coniine, suggesting stereoselectivity by the receptor. The pyridine alkaloid nicotine did not inhibit fetal movement in a day 40 pregnant goat model, suggesting agonist specificity for the inhibition of fetal movement. Low concentrations of both CTxs potentiated the TE-671 cell response and higher concentrations of CTx EI, and GI antagonized the actions of both coniine enantiomers demonstrating concentration-dependent coagonism and selective antagonism. These results provide pharmacological evidence that the piperidine alkaloid coniine is acting at fetal muscle-type nAChR in a concentration-dependent manner.

Selectivity to Translational Egomotion in Human Brain Motion Areas

PubMed Central

Pitzalis, Sabrina; Sdoia, Stefano; Bultrini, Alessandro; Committeri, Giorgia; Di Russo, Francesco; Fattori, Patrizia; Galletti, Claudio; Galati, Gaspare

2013-01-01

The optic flow generated when a person moves through the environment can be locally decomposed into several basic components, including radial, circular, translational and spiral motion. Since their analysis plays an important part in the visual perception and control of locomotion and posture it is likely that some brain regions in the primate dorsal visual pathway are specialized to distinguish among them. The aim of this study is to explore the sensitivity to different types of egomotion-compatible visual stimulations in the human motion-sensitive regions of the brain. Event-related fMRI experiments, 3D motion and wide-field stimulation, functional localizers and brain mapping methods were used to study the sensitivity of six distinct motion areas (V6, MT, MST+, V3A, CSv and an Intra-Parietal Sulcus motion [IPSmot] region) to different types of optic flow stimuli. Results show that only areas V6, MST+ and IPSmot are specialized in distinguishing among the various types of flow patterns, with a high response for the translational flow which was maximum in V6 and IPSmot and less marked in MST+. Given that during egomotion the translational optic flow conveys differential information about the near and far external objects, areas V6 and IPSmot likely process visual egomotion signals to extract information about the relative distance of objects with respect to the observer. Since area V6 is also involved in distinguishing object-motion from self-motion, it could provide information about location in space of moving and static objects during self-motion, particularly in a dynamically unstable environment. PMID:23577096

Classifying aerosol type using in situ surface spectral aerosol optical properties

NASA Astrophysics Data System (ADS)

Schmeisser, Lauren; Andrews, Elisabeth; Ogren, John A.; Sheridan, Patrick; Jefferson, Anne; Sharma, Sangeeta; Kim, Jeong Eun; Sherman, James P.; Sorribas, Mar; Kalapov, Ivo; Arsov, Todor; Angelov, Christo; Mayol-Bracero, Olga L.; Labuschagne, Casper; Kim, Sang-Woo; Hoffer, András; Lin, Neng-Huei; Chia, Hao-Ping; Bergin, Michael; Sun, Junying; Liu, Peng; Wu, Hao

2017-10-01

Knowledge of aerosol size and composition is important for determining radiative forcing effects of aerosols, identifying aerosol sources and improving aerosol satellite retrieval algorithms. The ability to extrapolate aerosol size and composition, or type, from intensive aerosol optical properties can help expand the current knowledge of spatiotemporal variability in aerosol type globally, particularly where chemical composition measurements do not exist concurrently with optical property measurements. This study uses medians of the scattering Ångström exponent (SAE), absorption Ångström exponent (AAE) and single scattering albedo (SSA) from 24 stations within the NOAA/ESRL Federated Aerosol Monitoring Network to infer aerosol type using previously published aerosol classification schemes.Three methods are implemented to obtain a best estimate of dominant aerosol type at each station using aerosol optical properties. The first method plots station medians into an AAE vs. SAE plot space, so that a unique combination of intensive properties corresponds with an aerosol type. The second typing method expands on the first by introducing a multivariate cluster analysis, which aims to group stations with similar optical characteristics and thus similar dominant aerosol type. The third and final classification method pairs 3-day backward air mass trajectories with median aerosol optical properties to explore the relationship between trajectory origin (proxy for likely aerosol type) and aerosol intensive parameters, while allowing for multiple dominant aerosol types at each station.The three aerosol classification methods have some common, and thus robust, results. In general, estimating dominant aerosol type using optical properties is best suited for site locations with a stable and homogenous aerosol population, particularly continental polluted (carbonaceous aerosol), marine polluted (carbonaceous aerosol mixed with sea salt) and continental dust/biomass sites (dust and carbonaceous aerosol); however, current classification schemes perform poorly when predicting dominant aerosol type at remote marine and Arctic sites and at stations with more complex locations and topography where variable aerosol populations are not well represented by median optical properties. Although the aerosol classification methods presented here provide new ways to reduce ambiguity in typing schemes, there is more work needed to find aerosol typing methods that are useful for a larger range of geographic locations and aerosol populations.

Near-infrared image-guided laser ablation of artificial caries lesions.

PubMed

Tao, You-Chen; Fan, Kenneth; Fried, Daniel

2007-01-01

Laser removal of dental hard tissue can be combined with optical, spectral or acoustic feedback systems to selectively ablate dental caries and restorative materials. Near-infrared (NIR) imaging has considerable potential for the optical discrimination of sound and demineralized tissue. The objective of this study was to test the hypothesis that two-dimensional NIR images of demineralized tooth surfaces can be used to guide CO(2) laser ablation for the selective removal of artificial caries lesions. Highly patterned artificial lesions were produced by submerging 5 × 5 mm(2) bovine enamel samples in demineralized solution for a 9-day period while sound areas were protected with acid resistant varnish. NIR imaging and polarization sensitive optical coherence tomography (PS-OCT) were used to acquire depth-resolved images at a wavelength of 1310-nm. An imaging processing module was developed to analyze the NIR images and to generate optical maps. The optical maps were used to control a CO(2) laser for the selective removal of the lesions at a uniform depth. This experiment showed that the patterned artificial lesions were removed selectively using the optical maps with minimal damage to sound enamel areas. Post-ablation NIR and PS-OCT imaging confirmed that demineralized areas were removed while sound enamel was conserved. This study successfully demonstrated that near-IR imaging can be integrated with a CO(2) laser ablation system for the selective removal of dental caries.

Near-infrared image-guided laser ablation of artificial caries lesions

PubMed Central

Tao, You-Chen; Fan, Kenneth; Fried, Daniel

2012-01-01

Laser removal of dental hard tissue can be combined with optical, spectral or acoustic feedback systems to selectively ablate dental caries and restorative materials. Near-infrared (NIR) imaging has considerable potential for the optical discrimination of sound and demineralized tissue. The objective of this study was to test the hypothesis that two–dimensional NIR images of demineralized tooth surfaces can be used to guide CO2 laser ablation for the selective removal of artificial caries lesions. Highly patterned artificial lesions were produced by submerging 5 × 5 mm2 bovine enamel samples in demineralized solution for a 9-day period while sound areas were protected with acid resistant varnish. NIR imaging and polarization sensitive optical coherence tomography (PS-OCT) were used to acquire depth-resolved images at a wavelength of 1310-nm. An imaging processing module was developed to analyze the NIR images and to generate optical maps. The optical maps were used to control a CO2 laser for the selective removal of the lesions at a uniform depth. This experiment showed that the patterned artificial lesions were removed selectively using the optical maps with minimal damage to sound enamel areas. Post-ablation NIR and PS-OCT imaging confirmed that demineralized areas were removed while sound enamel was conserved. This study successfully demonstrated that near-IR imaging can be integrated with a CO2 laser ablation system for the selective removal of dental caries. PMID:22866210

Near-infrared image-guided laser ablation of artificial caries lesions

NASA Astrophysics Data System (ADS)

Tao, You-Chen; Fan, Kenneth; Fried, Daniel

2007-02-01

Laser removal of dental hard tissue can be combined with optical, spectral or acoustic feedback systems to selectively ablate dental caries and restorative materials. Near-infrared (NIR) imaging has considerable potential for the optical discrimination of sound and demineralized tissue. The objective of this study was to test the hypothesis that two-dimensional NIR images of demineralized tooth surfaces can be used to guide CO II laser ablation for the selective removal of artificial caries lesions. Highly patterned artificial lesions were produced by submerging 5 x 5 mm2 bovine enamel samples in demineralized solution for a 9-day period while sound areas were protected with acid resistant varnish. NIR imaging and polarization sensitive optical coherence tomography (PS-OCT) were used to acquire depth-resolved images at a wavelength of 1310-nm. An imaging processing module was developed to analyze the NIR images and to generate optical maps. The optical maps were used to control a CO II laser for the selective removal of the lesions at a uniform depth. This experiment showed that the patterned artificial lesions were removed selectively using the optical maps with minimal damage to sound enamel areas. Post-ablation NIR and PS-OCT imaging confirmed that demineralized areas were removed while sound enamel was conserved. This study successfully demonstrated that near-IR imaging can be integrated with a CO II laser ablation system for the selective removal of dental caries.

Optical signal processing

NASA Astrophysics Data System (ADS)

Vanderlugt, A.

1993-07-01

A quasi-realtime adaptive processing system was used to correct the multipath distortion found in wideband digital radios. The measured power spectral density of the input signal was used to adaptively select one of eight equalization filters which reduce the residual distortion to less than 3.6 dB even for the most severe channel distortion. A related adaptive system was used for signal excision in which we removed narrowband interference from wideband signals with minimum signal distortion. An 8x8 acousto-optic switch in a multimode fiber-optic system was built. Insertion loss is approximately 2-4 dB, signal-to-crosstalk ratio is better than 25 dB, and the reconfiguration time is 880 nsec. Short pulses were detected by using the Fresnel transform. Pulses as short as the theoretical limit of 20 nanoseconds were detected for this system, and separated by as little as 60 nanoseconds or by as much as 17 nanoseconds. All possible acousto-optic scanning configurations were considered and classified into four basic types. A consistent set of design relationships for each of the scanning configurations was developed and presented in both tabular and graphic forms from which a preliminary design is obtained.

Three-dimensional cavity nanoantennas with resonant-enhanced surface plasmons as dynamic color-tuning reflectors.

PubMed

Fan, J R; Wu, W G; Chen, Z J; Zhu, J; Li, J

2017-03-09

As plasmonic antennas for surface-plasmon-assisted control of optical fields at specific frequencies, metallic nanostructures have recently emerged as crucial optical components for fascinating plasmonic color engineering. Particularly, plasmonic resonant nanocavities can concentrate lightwave energy to strongly enhance light-matter interactions, making them ideal candidates as optical elements for fine-tuning color displays. Inspired by the color mixing effect found on butterfly wings, a new type of plasmonic, multiresonant, narrow-band (the minimum is about 45 nm), high-reflectance (the maximum is about 95%), and dynamic color-tuning reflector is developed. This is achieved from periodic patterns of plasmonic resonant nanocavities in free-standing capped-pillar nanostructure arrays. Such cavity-coupling structures exhibit multiple narrow-band selective and continuously tunable reflections via plasmon standing-wave resonances. Consequently, they can produce a variety of dark-field vibrant reflective colors with good quality, strong color signal and fine tonal variation at the optical diffraction limit. This proposed multicolor scheme provides an elegant strategy for realizing personalized and customized applications in ultracompact photonic data storage and steganography, colorimetric sensing, 3D holograms and other plasmon-assisted photonic devices.

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.

Changing image of correlation optics: introduction.

PubMed

Angelsky, Oleg V; Desyatnikov, Anton S; Gbur, Gregory J; Hanson, Steen G; Lee, Tim; Miyamoto, Yoko; Schneckenburger, Herbert; Wyant, James C

2016-04-20

This feature issue of Applied Optics contains a series of selected papers reflecting recent progress of correlation optics and illustrating current trends in vector singular optics, internal energy flows at light fields, optical science of materials, and new biomedical applications of lasers.

Studies on Molecular and Ion Transport in Silicalite Membranes and Applications as Ion Separator for Redox Flow Battery

NASA Astrophysics Data System (ADS)

Yang, Ruidong

Microporous zeolite membranes have been widely studied for molecular separations based on size exclusion or preferential adsorption-diffusion mechanisms. The MFI-type zeolite membranes were also demonstrated for brine water desalination by molecular sieving effect. In this research, the pure silica MFI-type zeolite (i.e. silicalite) membrane has been for the first time demonstrated for selective permeation of hydrated proton (i.e. H3O+) in acidic electrolyte solutions. The silicalite membrane allows for permeation of H 3O+ ions, but is inaccessible to the large hydrated multivalent vanadium ions due to steric effect. The silicalite membrane has been further demonstrated as an effective ion separator in the all-vanadium redox flow battery (RFB).The silicalite is nonionic and its proton conductivity relies on the electric field-driven H3O+ transport through the sub nanometer-sized pores under the RFB operation conditions. The silicalite membrane displayed a significantly reduced self-discharge rate because of its high proton-to-vanadium ion transport selectivity. However, the nonionic nature of the silicalite membrane and very small diffusion channel size render low proton conductivity and is therefore inefficient as ion exchange membranes (IEMs) for practical applications. The proton transport efficiency may be improved by reducing the membrane thickness. However, the zeolite thin films are extremely fragile and must be supported on mechanically strong and rigid porous substrates. In this work, silicalite-Nafion composite membranes were synthesized to achieve a colloidal silicalite skin on the Nafion thin film base. The "colloidal zeolite-ionic polymer" layered composite membrane combines the advantages of high proton-selectivity of the zeolite layer and the mechanical flexibility and low proton transport resistance of the ionic polymer membrane. The composite membrane exhibited higher proton/vanadium ion separation selectivity and lower electrical resistance than the commercial Nafion 117 membrane. The high proton transport selectivity is a result of the molecular sieving effect between the H3O+ and multivalent vanadium ions by the zeolitic pores; thus the zeolite particles significantly reduced the effective membrane surface area for vanadium ion permeation. The low resistance of the composite membrane can be attributed to the reduced thickness of the Nafion base film and the thinness of the colloidal silicalite top layer. The composite membrane outperformed the Nafion 117 membrane in the vanadium RFB operation in terms of the overall charge-discharge energy efficiency. Efforts have been made in further investigation of ion and molecular transport diffusivity in the polycrystalline silicalite film using zeolite-coated optical fiber interferometers. A physical model has been established for analyzing the molecular diffusivity in the zeolite layer based on the temporal responses of the optical interferometric signals during the transient process of molecular sorption. Experiments were first carried out to study the diffusivity of isobutane to evaluate the effectiveness of the proposed optical method. The isobutane diffusivities in silicalite measured by this method were in good agreement with the values reported in literature. The zeolite coated fiber optic interferometer was however ineffective in monitoring ion sorption or ion exchange in the silicalite films. It is suggested that more sensitive fiber optic devices are needed for studying the ion diffusion.

Global Aerosol Optical Models and Lookup Tables for the New MODIS Aerosol Retrieval over Land

NASA Technical Reports Server (NTRS)

Levy, Robert C.; Remer, Loraine A.; Dubovik, Oleg

2007-01-01

Since 2000, MODIS has been deriving aerosol properties over land from MODIS observed spectral reflectance, by matching the observed reflectance with that simulated for selected aerosol optical models, aerosol loadings, wavelengths and geometrical conditions (that are contained in a lookup table or 'LUT'). Validation exercises have showed that MODIS tends to under-predict aerosol optical depth (tau) in cases of large tau (tau greater than 1.0), signaling errors in the assumed aerosol optical properties. Using the climatology of almucantur retrievals from the hundreds of global AERONET sunphotometer sites, we found that three spherical-derived models (describing fine-sized dominated aerosol), and one spheroid-derived model (describing coarse-sized dominated aerosol, presumably dust) generally described the range of observed global aerosol properties. The fine dominated models were separated mainly by their single scattering albedo (omega(sub 0)), ranging from non-absorbing aerosol (omega(sub 0) approx. 0.95) in developed urban/industrial regions, to neutrally absorbing aerosol (omega(sub 0) approx.90) in forest fire burning and developing industrial regions, to absorbing aerosol (omega(sub 0) approx. 0.85) in regions of savanna/grassland burning. We determined the dominant model type in each region and season, to create a 1 deg. x 1 deg. grid of assumed aerosol type. We used vector radiative transfer code to create a new LUT, simulating the four aerosol models, in four MODIS channels. Independent AERONET observations of spectral tau agree with the new models, indicating that the new models are suitable for use by the MODIS aerosol retrieval.

Crystallography with online optical and X-ray absorption spectroscopies demonstrates an ordered mechanism in copper nitrite reductase.

PubMed

Hough, Michael A; Antonyuk, Svetlana V; Strange, Richard W; Eady, Robert R; Hasnain, S Samar

2008-04-25

Nitrite reductases are key enzymes that perform the first committed step in the denitrification process and reduce nitrite to nitric oxide. In copper nitrite reductases, an electron is delivered from the type 1 copper (T1Cu) centre to the type 2 copper (T2Cu) centre where catalysis occurs. Despite significant structural and mechanistic studies, it remains controversial whether the substrates, nitrite, electron and proton are utilised in an ordered or random manner. We have used crystallography, together with online X-ray absorption spectroscopy and optical spectroscopy, to show that X-rays rapidly and selectively photoreduce the T1Cu centre, but that the T2Cu centre does not photoreduce directly over a typical crystallographic data collection time. Furthermore, internal electron transfer between the T1Cu and T2Cu centres does not occur, and the T2Cu centre remains oxidised. These data unambiguously demonstrate an 'ordered' mechanism in which electron transfer is gated by binding of nitrite to the T2Cu. Furthermore, the use of online multiple spectroscopic techniques shows their value in assessing radiation-induced redox changes at different metal sites and demonstrates the importance of ensuring the correct status of redox centres in a crystal structure determination. Here, optical spectroscopy has shown a very high sensitivity for detecting the change in T1Cu redox state, while X-ray absorption spectroscopy has reported on the redox status of the T2Cu site, as this centre has no detectable optical absorption.

Early valproic acid exposure alters functional organization in the primary visual cortex

PubMed Central

Pohl-Guimaraes, Fernanda; Krahe, Thomas E.; Medina, Alexandre E.

2018-01-01

Epilepsy is one of the most common neurologic disorders and affects 0.5 to 1% of pregnant women. The use of antiepileptic drugs, which is usually continued throughout pregnancy, can cause in offspring mild to severe sensory deficits. Neuronal selectivity to stimulus orientation is a basic functional property of the visual cortex that is crucial for perception of shapes and borders. Here we investigate the effects of early exposure to valproic acid (Val) and levetiracetam (Lev), commonly used antiepileptic drugs, on the development of cortical neuron orientation selectivity and organization of cortical orientation columns. Ferrets pups were exposed to Val (200 mg/kg), Lev (100 mg/kg) or saline every other day between postnatal day (P) 10 and P30, a period roughly equivalent to the third trimester of human gestation. Optical imaging of intrinsic signals or single-unit recordings were examined at P42–P84, when orientation selectivity in the ferret cortex has reached a mature state. Optical imaging of intrinsic signals revealed decreased contrast of orientation maps in Val-but not Lev- or saline-treated animals. Moreover, single-unit recordings revealed that early Val treatment also reduced orientation selectivity at the cellular level. These findings indicate that Val exposure during a brief period of development disrupts cortical processing of sensory information at a later age and suggest a neurobiological substrate for some types of sensory deficits in fetal anticonvulsant syndrome. PMID:21215743

Early valproic acid exposure alters functional organization in the primary visual cortex.

PubMed

Pohl-Guimaraes, Fernanda; Krahe, Thomas E; Medina, Alexandre E

2011-03-01

Epilepsy is one of the most common neurologic disorders and affects 0.5 to 1% of pregnant women. The use of antiepileptic drugs, which is usually continued throughout pregnancy, can cause in offspring mild to severe sensory deficits. Neuronal selectivity to stimulus orientation is a basic functional property of the visual cortex that is crucial for perception of shapes and borders. Here we investigate the effects of early exposure to valproic acid (Val) and levetiracetam (Lev), commonly used antiepileptic drugs, on the development of cortical neuron orientation selectivity and organization of cortical orientation columns. Ferrets pups were exposed to Val (200mg/kg), Lev (100mg/kg) or saline every other day between postnatal day (P) 10 and P30, a period roughly equivalent to the third trimester of human gestation. Optical imaging of intrinsic signals or single-unit recordings were examined at P42-P84, when orientation selectivity in the ferret cortex has reached a mature state. Optical imaging of intrinsic signals revealed decreased contrast of orientation maps in Val- but not Lev- or saline-treated animals. Moreover, single-unit recordings revealed that early Val treatment also reduced orientation selectivity at the cellular level. These findings indicate that Val exposure during a brief period of development disrupts cortical processing of sensory information at a later age and suggest a neurobiological substrate for some types of sensory deficits in fetal anticonvulsant syndrome. Copyright © 2011 Elsevier Inc. All rights reserved.

Method and system for evaluating integrity of adherence of a conductor bond to a mating surface of a substrate

DOEpatents

Telschow, K.L.; Siu, B.K.

1996-07-09

A method of evaluating integrity of adherence of a conductor bond to a substrate includes: (a) impinging a plurality of light sources onto a substrate; (b) detecting optical reflective signatures emanating from the substrate from the impinged light; (c) determining location of a selected conductor bond on the substrate from the detected reflective signatures; (d) determining a target site on the selected conductor bond from the detected reflective signatures; (e) optically imparting an elastic wave at the target site through the selected conductor bond and into the substrate; (f) optically detecting an elastic wave signature emanating from the substrate resulting from the optically imparting step; and (g) determining integrity of adherence of the selected conductor bond to the substrate from the detected elastic wave signature emanating from the substrate. A system is disclosed which is capable of conducting the method. 13 figs.

Method and system for evaluating integrity of adherence of a conductor bond to a mating surface of a substrate

DOEpatents

Telschow, Kenneth L.; Siu, Bernard K.

1996-01-01

A method of evaluating integrity of adherence of a conductor bond to a substrate includes: a) impinging a plurality of light sources onto a substrate; b) detecting optical reflective signatures emanating from the substrate from the impinged light; c) determining location of a selected conductor bond on the substrate from the detected reflective signatures; d) determining a target site on the selected conductor bond from the detected reflective signatures; e) optically imparting an elastic wave at the target site through the selected conductor bond and into the substrate; f) optically detecting an elastic wave signature emanating from the substrate resulting from the optically imparting step; and g) determining integrity of adherence of the selected conductor bond to the substrate from the detected elastic wave signature emanating from the substrate. A system is disclosed which is capable of conducting the method.

Angular dependence of Raman scattering selection rules for long-wavelength optical phonons in short-period GaAs/AlAs superlattices

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

Volodin, V. A., E-mail: volodin@isp.nsc.ru; Sachkov, V. A.; Sinyukov, M. P.

2016-07-15

The angular dependence of Raman scattering selection rules for optical phonons in short-period (001) GaAs/AlAs superlattices is calculated and experimentally studied. Experiments are performed using a micro-Raman setup, in the scattering geometry with the wavevectors of the incident and scattered light lying in the plane of superlattices (so-called in-plane geometry). Phonon frequencies are calculated using the Born model taking the Coulomb interaction into account in the rigid-ion approximation. Raman scattering spectra are calculated in the framework of the deformation potential and electro-optical mechanisms. Calculations show an angular dependence of the selection rules for optical phonons with different directions of themore » wavevectors. Drastic differences in the selection rules are found for experimental and calculated spectra. Presumably, these differences are due to the Fröhlich mechanism in Raman scattering for short-period superlattices.« less

Dosimetry in dentistry.

PubMed

Asha, M L; Chatterjee, Ingita; Patil, Preeti; Naveen, S

2015-01-01

The purpose of this paper was to review various dosimeters used in dentistry and the cumulative results of various studies done with various dosimeters. Several relevant PubMed indexed articles from 1999 to 2013 were electronically searched by typing "dosimeters", "dosimeters in dentistry", "properties of dosimeters", "thermoluminescent and optically stimulated dosimeters", "recent advancements in dosimetry in dentistry." The searches were limited to articles in English to prepare a concise review on dental dosimetry. Titles and abstracts were screened, and articles that fulfilled the criteria of use of dosimeters in dental applications were selected for a full-text reading. Article was divided into four groups: (1) Biological effects of radiation, (2) properties of dosimeters, (3) types of dosimeters and (4) results of various studies using different dosimeters. The present review on dosimetry based on various studies done with dosimeters revealed that, with the advent of radiographic technique the effective dose delivered is low. Therefore, selection of radiological technique plays an important role in dental dose delivery.

Nonlinear optical selection rule based on valley-exciton locking in monolayer ws 2

DOE PAGES

Xiao, Jun; Ye, Ziliang; Wang, Ying; ...

2015-12-18

Optical selection rules fundamentally determine the optical transitions between energy states in a variety of physical systems, from hydrogen atoms to bulk crystals such as gallium arsenide. These rules are important for optoelectronic applications such as lasers, energy-dispersive X-ray spectroscopy, and quantum computation. Recently, single-layer transition metal dichalcogenides have been found to exhibit valleys in momentum space with nontrivial Berry curvature and excitons with large binding energy. However, there has been little study of how the unique valley degree of freedom combined with the strong excitonic effect influences the nonlinear optical excitation. Here in this paper, we report the discoverymore » of nonlinear optical selection rules in monolayer WS 2, an important candidate for visible 2D optoelectronics because of its high quantum yield and large direct bandgap. We experimentally demonstrated this principle for second-harmonic generation and two-photon luminescence (TPL). Moreover, the circularly polarized TPL and the study of its dynamics evince a sub-ps interexciton relaxation (2p → 1s). The discovery of this new optical selection rule in a valleytronic 2D system not only considerably enhances knowledge in this area but also establishes a foundation for the control of optical transitions that will be crucial for valley optoelectronic device applications such as 2D valley-polarized THz sources with 2p-1s transitions, optical switches, and coherent control for quantum computing.« less

Fiber optic sensors

NASA Technical Reports Server (NTRS)

Hesse, J.; Sohler, W.

1984-01-01

A survey of the developments in the field of fiber optics sensor technology is presented along with a discussion of the advantages of optical measuring instruments as compared with electronic sensors. The two primary types of fiber optics sensors, specifically those with multiwave fibers and those with monowave fibers, are described. Examples of each major sensor type are presented and discussed. Multiwave detectors include external and internal fiber optics sensors. Among the monowave detectors are Mach-Zender interferometers, Michelson interferometers, Sagnac interferometers (optical gyroscopes), waveguide resonators, and polarimeter sensors. Integrated optical sensors and their application in spectroscopy are briefly discussed.

NbN tunnel junctions

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

Villegier, J.C.; Goniche, M.; Renard, P.

1985-03-01

All-niobium nitride Josephson junctions have been prepared successfully using a new processing called SNOP: Selective Niobium (Nitride) Overlap Process. Such a process involves the ''trilayer'' deposition on the whole wafer before selective patterning of the electrodes by optically controlled Dry Reactive Ion Etching. Only two photomask levels are need to define an ''overlap'' or a ''cross-type'' junction with a good accuracy. The properties of the niobium nitride films deposited by DC-Magnetron sputtering and the surface oxide growth are analysed. The most critical point to obtain high quality and high gap value junctions resides in the early stage of the NbNmore » counterelectrode growth. Some possibilities to overcome such a handicap exist even if the fabrication needs substrate temperatures below 250/sup 0/C.« less

Stereocontrolled dopamine receptor binding and subtype selectivity of clebopride analogues synthesized from aspartic acid.

PubMed

Einsiedel, Jürgen; Weber, Klaus; Thomas, Christoph; Lehmann, Thomas; Hübner, Harald; Gmeiner, Peter

2003-10-06

Employing the achiral 4-aminopiperidine derivative clebopride as a lead compound, chiral analogues were developed displaying dopamine receptor binding profiles that proved to be strongly dependent on the stereochemistry. Compared to the D1 receptor, the test compounds showed high selectivity for the D2-like subtypes including D2(long), D2(short), D3 and D4. The highest D4 and D3 affinities were observed for the cis-3-amino-4-methylpyrrolidines 3e and the enantiomer ent3e resulting in K(i) values of 0.23 and 1.8 nM, respectively. The benzamides of type 3 and 5 were synthesized in enantiopure form starting from (S)-aspartic acid and its unnatural optical antipode.

Scalable InP integrated wavelength selector based on binary search.

PubMed

Calabretta, Nicola; Stabile, Ripalta; Albores-Mejia, Aaron; Williams, Kevin A; Dorren, Harm J S

2011-10-01

We present an InP monolithically integrated wavelength selector that implements a binary search for selecting one from N modulated wavelengths. The InP chip requires only log(2)N optical filters and log(2)N optical switches. Experimental results show nanosecond reconfiguration and error-free wavelength selection of four modulated wavelengths with 2 dB of power penalty. © 2011 Optical Society of America

Luciferase-Specific Coelenterazine Analogues for Optical Contamination-Free Bioassays.

PubMed

Nishihara, Ryo; Abe, Masahiro; Nishiyama, Shigeru; Citterio, Daniel; Suzuki, Koji; Kim, Sung Bae

2017-04-19

Spectral overlaps among the multiple optical readouts commonly cause optical contamination in fluorescence and bioluminescence. To tackle this issue, we created five-different lineages of coelenterazine (CTZ) analogues designed to selectively illuminate a specific luciferase with unique luciferase selectivity. In the attempt, we found that CTZ analogues with ethynyl or styryl groups display dramatically biased bioluminescence to specific luciferases and pHs by modifying the functional groups at the C-2 and C-6 positions of the imidazopyradinone backbone of CTZ. The optical contamination-free feature was exemplified with the luciferase-specific CTZ analogues, which illuminated anti-estrogenic and rapamycin activities in a mixture of optical probes. This unique bioluminescence platform has great potential for specific and high throughput imaging of multiple optical readouts in bioassays without optical contamination.

NuSTAR Reveals Extreme Absorption in z < 0.5 Type 2 Quasars

NASA Astrophysics Data System (ADS)

Lansbury, G. B.; Gandhi, P.; Alexander, D. M.; Assef, R. J.; Aird, J.; Annuar, A.; Ballantyne, D. R.; Baloković, M.; Bauer, F. E.; Boggs, S. E.; Brandt, W. N.; Brightman, M.; Christensen, F. E.; Civano, F.; Comastri, A.; Craig, W. W.; Del Moro, A.; Grefenstette, B. W.; Hailey, C. J.; Harrison, F. A.; Hickox, R. C.; Koss, M.; LaMassa, S. M.; Luo, B.; Puccetti, S.; Stern, D.; Treister, E.; Vignali, C.; Zappacosta, L.; Zhang, W. W.

2015-08-01

The intrinsic column density (NH) distribution of quasars is poorly known. At the high obscuration end of the quasar population and for redshifts z < 1, the X-ray spectra can only be reliably characterized using broad-band measurements that extend to energies above 10 keV. Using the hard X-ray observatory NuSTAR, along with archival Chandra and XMM-Newton data, we study the broad-band X-ray spectra of nine optically selected (from the SDSS), candidate Compton-thick (NH > 1.5 × 1024 cm-2) type 2 quasars (CTQSO2s); five new NuSTAR observations are reported herein, and four have been previously published. The candidate CTQSO2s lie at z < 0.5, have observed [O iii] luminosities in the range 8.4\\lt {log}({L}[{{O} {{III}}]}/{L}⊙ )\\lt 9.6, and show evidence for extreme, Compton-thick absorption when indirect absorption diagnostics are considered. Among the nine candidate CTQSO2s, five are detected by NuSTAR in the high-energy (8-24 keV) band: two are weakly detected at the ≈3σ confidence level and three are strongly detected with sufficient counts for spectral modeling (≳90 net source counts at 8-24 keV). For these NuSTAR-detected sources direct (i.e., X-ray spectral) constraints on the intrinsic active galactic nucleus properties are feasible, and we measure column densities ≈2.5-1600 times higher and intrinsic (unabsorbed) X-ray luminosities ≈10-70 times higher than pre-NuSTAR constraints from Chandra and XMM-Newton. Assuming the NuSTAR-detected type 2 quasars are representative of other Compton-thick candidates, we make a correction to the NH distribution for optically selected type 2 quasars as measured by Chandra and XMM-Newton for 39 objects. With this approach, we predict a Compton-thick fraction of {f}{CT}={36}-12+14 %, although higher fractions (up to 76%) are possible if indirect absorption diagnostics are assumed to be reliable.

Sphenoid sinus types, dimensions and relationship with surrounding structures.

PubMed

Štoković, Nikola; Trkulja, Vladimir; Dumić-Čule, Ivo; Čuković-Bagić, Ivana; Lauc, Tomislav; Vukičević, Slobodan; Grgurević, Lovorka

2016-01-01

The human sphenoid sinus is an extremely variable cavity and an important landmark in hypophyseal surgery. The aim of this study was to investigate the relationship between the sphenoid sinus type, size, extent of pneumatization and occurrence of protrusions of the adjacent neurovascular structures. A total of 51 randomly selected skulls (≥20 years of age, 33 male; 102 sinuses) were analyzed using cone beam computed tomography to estimate pneumatization extension beyond the body of the sphenoid (planum sphenoidale, pterygoid process, greater wings, clivus, dorsum sellae) and protrusions of the maxillary, mandibular, optic or pterygoid nerve or the internal carotid artery. Difference in pneumatization type between the left and the right-sided sinus was observed in 45% of the skulls. Conchal pneumatization was registered in 2%, presellar in 24%, sellar in 41% and postsellar in 33% of total sinuses. Presellar sinuses frequently pneumatized planum sphenoidale and sporadically other structures, and were characterized by sporadic optic nerve protrusions. Sellar and particularly postsellar sinuses were characterized by simultaneous pneumatization extensions and neurovascular protrusions. In the case of postsellar-type sinuses, the probability of these multiple interactions was not affected by their actual size, while it increased with the increasing sinus dimensions in the case of sellar-type sinuses. A more detailed analysis indicated that increasing sinus height, length or width increased the probability of interactions and pneumatization of particular surrounding structures. Data suggest that the sphenoid sinus pneumatization type and dimensions might be used to estimate the risks of iatrogenic injury during transsphenoidal surgical procedures. Copyright © 2015 Elsevier GmbH. All rights reserved.

Apparatus and process for determining the susceptibility of microorganisms to antibiotics

NASA Technical Reports Server (NTRS)

Gibson, Sandra F. (Inventor); Fadler, Norman L. (Inventor)

1976-01-01

A process for determining the susceptibility of microorganisms to antibiotics involves introducing a diluted specimen into discrete quantities of a selective culture medium which favors a specific microorganism in that the microorganism is sustained by the medium and when so sustained will change the optical characteristics of the medium. Only the specific microorganism will alter the optical characteristics. Some of the discrete quantities are blended with known antibiotics, while at least one is not. If the specimen contains the microorganisms favored by the selective medium, the optical characteristics of the discrete quantity of pure selective medium, that is the one without antibiotics, will change. If the antibiotics in any of the other discrete quantities are ineffective against the favored microorganisms, the optical characteristics of those quantities will likewise change. No change in the optical characteristics of a discrete quantity indicates that the favored microorganism is susceptible to the antibiotic in the quantity.

Optical-NIR dust extinction towards Galactic O stars

NASA Astrophysics Data System (ADS)

Maíz Apellániz, J.; Barbá, R. H.

2018-05-01

Context. O stars are excellent tracers of the intervening ISM because of their high luminosity, blue intrinsic SED, and relatively featureless spectra. We are currently conducting the Galactic O-Star Spectroscopic Survey (GOSSS), which is generating a large sample of O stars with accurate spectral types within several kpc of the Sun. Aims: We aim to obtain a global picture of the properties of dust extinction in the solar neighborhood based on optical-NIR photometry of O stars with accurate spectral types. Methods: We have processed a carefully selected photometric set with the CHORIZOS code to measure the amount [E(4405 - 5495)] and type [R5495] of extinction towards 562 O-type stellar systems. We have tested three different families of extinction laws and analyzed our results with the help of additional archival data. Results: The Maíz Apellániz et al. (2014, A&A, 564, A63) family of extinction laws provides a better description of Galactic dust that either the Cardelli et al. (1989, ApJ, 345, 245) or Fitzpatrick (1999, PASP, 111, 63) families, so it should be preferentially used when analysing samples similar to the one in this paper. In many cases O stars and late-type stars experience similar amounts of extinction at similar distances but some O stars are located close to the molecular clouds left over from their births and have larger extinctions than the average for nearby late-type populations. In qualitative terms, O stars experience a more diverse extinction than late-type stars, as some are affected by the small-grain-size, low-R5495 effect of molecular clouds and others by the large-grain-size, high-R5495 effect of H II regions. Late-type stars experience a narrower range of grain sizes or R5495, as their extinction is predominantly caused by the average, diffuse ISM. We propose that the reason for the existence of large-grain-size, high-R5495 regions in the ISM in the form of H II regions and hot-gas bubbles is the selective destruction of small dust grains by EUV photons and possibly by thermal sputtering by atoms or ions. Table 1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/613/A9

Optical pulse synthesis using brillouin selective sideband amplification

NASA Technical Reports Server (NTRS)

Yao, X. Steve (Inventor)

2002-01-01

Techniques for producing optical pulses based on Brillouin selective sideband amplification by using a common modulation control signal to modulate both a signal beam to produce multiple sideband signals and a single pump beam to produce multiple pump beams.

Highly Reliable PON Optical Splitters for Optical Access Networks in Outside Environments

NASA Astrophysics Data System (ADS)

Watanabe, Hiroshi; Araki, Noriyuki; Fujimoto, Hisashi

Broadband optical access services are spreading throughout the world, and the number of fiber to the home (FTTH) subscribers is increasing rapidly. Telecom operators are constructing passive optical networks (PONs) to provide optical access services. Externally installed optical splitters for PONs are very important passive devices in optical access networks, and they must provide satisfactory performance as outdoor plant over long periods. Therefore, we calculate the failure rate of optical access networks and assign a failure rate to the optical splitters in optical access networks. The maximum cumulative failure rate of 1 × 8 optical splitters was calculated as 0.025 for an optical access fiber length of 2.1km and a 20-year operating lifetime. We examined planar lightwave circuit (PLC) type optical splitters for use as outside plant in terms of their optical characteristics and environmental reliability. We confirmed that PLC type optical splitters have sufficient optical performance for a PON splitter and sufficient reliability as outside plant in accordance with ITU-T standard values. We estimated the lifetimes of three kinds of PLC type optical splitters by using accelerated aging tests. The estimated failure rate of these splitters installed in optical access networks was below the target value for the cumulative failure rate, and we confirmed that they have sufficient reliability to maintain the quality of the network service. We developed 1 × 8 optical splitter modules with plug and socket type optical connectors and optical fiber cords for optical aerial closures designed for use as outside plant. These technologies make it easy to install optical splitters in an aerial optical closure. The optical splitter modules have sufficient optical performance levels for PONs because the insertion loss at the commercially used wavelengths of 1.31 and 1.55µm is less than the criterion established by ITU-T Recommendation G.671 for optical splitters. We performed a temperature cycling test, and a low temperature storage and damp heat test to confirm the long-term reliability of these modules. They exhibited sufficient reliability as regards heat and moisture because the maximum loss change was less than 0.3dB.

Starburst Galaxies. II. Imaging and Spectroscopy of a Radio-selected Sample

NASA Astrophysics Data System (ADS)

Smith, Denise A.; Herter, Terry; Haynes, Martha P.; Beichman, C. A.; Gautier, T. N., III

1996-06-01

We present J-, H-, and K-band images and low-resolution K-band spectra of the 20 most luminous starburst galaxies from the survey of Condon, Frayer, & Broderick. Optical rotation curves are also shown for 10 of these galaxies. Near-infrared colors, optical depths, CO indices, and dynamical masses are calculated. The near-infrared colors of the starburst nuclei are significantly redder than those observed in "normal" galaxies. Together, the Brγ and radio fluxes available for five of the galaxies imply that the starbursts are heavily obscured; an average extinction of A_V_~ 25 is derived. Strong CO absorption features indicate that late-type evolved stars are present in many of the starbursts. The average dynamical mass of the starburst region is found to be (1.0 +/- 0.4) x 10^9^ M_sun_.

Classification of wet aged related macular degeneration using optical coherence tomographic images

NASA Astrophysics Data System (ADS)

Haq, Anam; Mir, Fouwad Jamil; Yasin, Ubaid Ullah; Khan, Shoab A.

2013-12-01

Wet Age related macular degeneration (AMD) is a type of age related macular degeneration. In order to detect Wet AMD we look for Pigment Epithelium detachment (PED) and fluid filled region caused by choroidal neovascularization (CNV). This form of AMD can cause vision loss if not treated in time. In this article we have proposed an automated system for detection of Wet AMD in Optical coherence tomographic (OCT) images. The proposed system extracts PED and CNV from OCT images using segmentation and morphological operations and then detailed feature set are extracted. These features are then passed on to the classifier for classification. Finally performance measures like accuracy, sensitivity and specificity are calculated and the classifier delivering the maximum performance is selected as a comparison measure. Our system gives higher performance using SVM as compared to other methods.

IRAS 17380 - 3031 - A new dusty late WC-type Wolf-Rayet star

NASA Astrophysics Data System (ADS)

Cohen, Martin; van der Hucht, K. A.; Williams, P. M.; The, P. S.

1991-09-01

Infrared photometry is presented of IRAS 17380 - 3031 and of IRAS 18405 - 0448, two of the proposed candidates for late WC-type stars suggested by Vok and Cohen (1989). Systematic 12-micron flux-limited surveys of the complete IRAS low-resolution spectrometer (LSR) data base show that late-type WC (WCL) stars with circumstellar dust emission have unique midinfrared spectra, suggesting a novel method for detecting such stars. It is confirmed through optical spectroscopy that IRAS 17380 - 3031, a prime LRS-selected WCL candidate, is a very red WCL star. It is classified as WC8 - 9, with a probable distance of 3 + or - 1 kpc, and a total extinction of about 12.5 mag. The confirmation demonstrates the power of the LRS technique for discovery of dusty WCL stars with IRAS.

Antibody Recognition of a Human Chorionic Gonadotropin Epitope (hCGβ66–80) Depends on Local Structure Retained in the Free Peptide*

PubMed Central

Gregor, Craig R.; Cerasoli, Eleonora; Schouten, James; Ravi, Jascindra; Slootstra, Jerry; Horgan, Adrian; Martyna, Glenn J.; Ryadnov, Maxim G.; Davis, Paul; Crain, Jason

2011-01-01

Human chorionic gonadotropin (hCG) is an important biomarker in pregnancy and oncology, where it is routinely detected and quantified by specific immunoassays. Intelligent epitope selection is essential to achieving the required assay performance. We present binding affinity measurements demonstrating that a typical β3-loop-specific monoclonal antibody (8G5) is highly selective in competitive immunoassays and distinguishes between hCGβ66–80 and the closely related luteinizing hormone (LH) fragment LHβ86–100, which differ only by a single amino acid residue. A combination of optical spectroscopic measurements and atomistic computer simulations on these free peptides reveals differences in turn type stabilized by specific hydrogen bonding motifs. We propose that these structural differences are the basis for the observed selectivity in the full protein. PMID:21592960

High-spatial-resolution K-band Imaging of Select K2 Campaign Fields

NASA Astrophysics Data System (ADS)

Colón, Knicole D.; Howell, Steve B.; Ciardi, David R.; Barclay, Thomas

2017-12-01

NASA's K2 mission began observing fields along the ecliptic plane in 2014. Each observing campaign lasts approximately 80 days, during which high-precision optical photometry of select astrophysical targets is collected by the Kepler spacecraft. Due to the 4 arcsec pixel scale of the Kepler photometer, significant blending between the observed targets can occur (especially in dense fields close to the Galactic plane). We undertook a program to use the Wide Field Camera (WFCAM) on the 3.8 m United Kingdom InfraRed Telescope (UKIRT) to collect high-spatial-resolution near-infrared images of targets in select K2 campaign fields, which we report here. These 0.4 arcsec resolution K-band images offer the opportunity to perform a variety of science, including vetting exoplanet candidates by identifying nearby stars blended with the target star and estimating the size, color, and type of galaxies observed by K2.

LIVAS: a 3-D multi-wavelength aerosol/cloud database based on CALIPSO and EARLINET

NASA Astrophysics Data System (ADS)

Amiridis, V.; Marinou, E.; Tsekeri, A.; Wandinger, U.; Schwarz, A.; Giannakaki, E.; Mamouri, R.; Kokkalis, P.; Binietoglou, I.; Solomos, S.; Herekakis, T.; Kazadzis, S.; Gerasopoulos, E.; Proestakis, E.; Kottas, M.; Balis, D.; Papayannis, A.; Kontoes, C.; Kourtidis, K.; Papagiannopoulos, N.; Mona, L.; Pappalardo, G.; Le Rille, O.; Ansmann, A.

2015-07-01

We present LIVAS (LIdar climatology of Vertical Aerosol Structure for space-based lidar simulation studies), a 3-D multi-wavelength global aerosol and cloud optical database, optimized to be used for future space-based lidar end-to-end simulations of realistic atmospheric scenarios as well as retrieval algorithm testing activities. The LIVAS database provides averaged profiles of aerosol optical properties for the potential spaceborne laser operating wavelengths of 355, 532, 1064, 1570 and 2050 nm and of cloud optical properties at the wavelength of 532 nm. The global database is based on CALIPSO observations at 532 and 1064 nm and on aerosol-type-dependent backscatter- and extinction-related Ångström exponents, derived from EARLINET (European Aerosol Research Lidar Network) ground-based measurements for the UV and scattering calculations for the IR wavelengths, using a combination of input data from AERONET, suitable aerosol models and recent literature. The required spectral conversions are calculated for each of the CALIPSO aerosol types and are applied to CALIPSO backscatter and extinction data corresponding to the aerosol type retrieved by the CALIPSO aerosol classification scheme. A cloud optical database based on CALIPSO measurements at 532 nm is also provided, neglecting wavelength conversion due to approximately neutral scattering behavior of clouds along the spectral range of LIVAS. Averages of particle linear depolarization ratio profiles at 532 nm are provided as well. Finally, vertical distributions for a set of selected scenes of specific atmospheric phenomena (e.g., dust outbreaks, volcanic eruptions, wild fires, polar stratospheric clouds) are analyzed and spectrally converted so as to be used as case studies for spaceborne lidar performance assessments. The final global data set includes 4-year (1 January 2008-31 December 2011) time-averaged CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) data on a uniform grid of 1° × 1° with the original high vertical resolution of CALIPSO in order to ensure realistic simulations of the atmospheric variability in lidar end-to-end simulations.

Phosphodiesterase Inhibition Increases CREB Phosphorylation and Restores Orientation Selectivity in a Model of Fetal Alcohol Spectrum Disorders

PubMed Central

Krahe, Thomas E.; Wang, Weili; Medina, Alexandre E.

2009-01-01

Background Fetal alcohol spectrum disorders (FASD) are the leading cause of mental retardation in the western world and children with FASD present altered somatosensory, auditory and visual processing. There is growing evidence that some of these sensory processing problems may be related to altered cortical maps caused by impaired developmental neuronal plasticity. Methodology/Principal Findings Here we show that the primary visual cortex of ferrets exposed to alcohol during the third trimester equivalent of human gestation have decreased CREB phosphorylation and poor orientation selectivity revealed by western blotting, optical imaging of intrinsic signals and single-unit extracellular recording techniques. Treating animals several days after the period of alcohol exposure with a phosphodiesterase type 1 inhibitor (Vinpocetine) increased CREB phosphorylation and restored orientation selectivity columns and neuronal orientation tuning. Conclusions/Significance These findings suggest that CREB function is important for the maturation of orientation selectivity and that plasticity enhancement by vinpocetine may play a role in the treatment of sensory problems in FASD. PMID:19680548

Dosimetry control and monitoring of selective retina therapy using optical coherence tomography

NASA Astrophysics Data System (ADS)

Kaufmann, Daniel; Burri, Christian; Arnold, Patrik; Koch, Volker M.; Meier, Christoph; Považay, Boris; Justiz, Joern

2017-07-01

Selective retina therapy and optical coherence tomography have been combined to monitor laser-tissue interaction in real-time. An ex-vivo study of porcine eyes unveils mechanisms that enable automated and accurate dose-control during laser-therapy.

Calendar of Selected Aeronautical and Space Meetings (Calendrier des Manifestations Aeronautiques et Spatiales (Selection)).

DTIC Science & Technology

1983-01-01

Physique de l’Atmosphire et Environnement terrestre 71 09 - Information, Documentation et Informatique 74 10 - Thimes gin~raux (pluridisciplinaires) et...March Louisiana (US) Fiber Communication Optical Communications IEEE Fibre Optics Electro-Optics 02-08 7-9 March Baden-Baden VDE -IEEE Specialists...Conference on Very Large Electronic Systems VDE (GE) Scale Integrated Circuits Solid State Devices IEEE Integrated Circuits Engineering Design Fabrication

An XMM-Newton spectral survey of 12 μm selected galaxies - II. Implications for AGN selection and unification

NASA Astrophysics Data System (ADS)

Brightman, Murray; Nandra, Kirpal

2011-07-01

We present a multi-waveband analysis of a 126-galaxy sub-sample of the 12 μm galaxy sample (12MGS), for which we have carried out a detailed X-ray spectral analysis in a previous paper. We determine the activity class of the galaxies by way of optical-line ratio diagnostics and characterize the optical classes by their X-ray, 12 μm and [O III] luminosities and X-ray spectral properties. Our most interesting results from this investigation are as follows. (i) Seyfert (Sy) 1s and Sy2s show a significantly different X-ray luminosity distributions from each other. (ii) Sy2 galaxies with a detection of a hidden broad-line region show a significantly higher X-ray luminosity than those without a detection, supporting the findings of Tran. (iii) Sy1s also present a significantly different 12 μm luminosity distribution from both intermediate Sy types and Sy2s. (iv) The Sy2 fraction decreases towards high X-ray luminosities. (v) X-ray indications of active galactic nuclei (AGN) power agree well with the optical classifications. (vi) There is X-ray evidence for the presence of an AGN in 17 per cent of H II/AGN composite galaxies and 40 per cent of LINERs. (vii) We advocate the use of a 2-10 keV X-ray luminosity of 1041 erg s-1 in the X-ray selection of AGN, rather than 1042 erg s-1, which we find gives a contamination rate of only 3 per cent from star-forming galaxies. (viii) From an analysis of the X-ray power-law index, Γ, we find that Sy1s and Sy2 have the same intrinsic distributions, implying that the central engines are the same, in support of AGN unification schemes. (ix) In 24 per cent of cases the absorption measured in the X-ray spectra does not correspond directly to that implied in the optical band from the visibility of the broad-line regions (BLRs), which is in conflict with AGN unification schemes. (x) We confirm the previous work showing that the obscured fraction in AGN declines at high X-ray luminosity, but also find a decrease at low luminosity having peaked at LX˜ 1042 erg s-1, suggesting that source luminosity has a large effect on the obscuring material, therefore also calling for a modification to unified schemes. (xi) The average obscured and Compton-thick fractions for this sample are 62 ± 5 per cent and 20 ± 4 per cent, respectively, which are higher than hard X-ray and optically selected samples, therefore supporting mid-infrared (MIR) selection as a relatively unbiased method of selecting AGN. (xii) We assess the use of the 'T' ratio (?) for selecting Compton-thick candidates. We conclude here that this quantity can often be unreliable due to uncertainties in the extinction corrections to the [O III] flux. These results have important impacts on AGN selection and unification, and the results from the 12MGS are particularly useful as a local analogue to Spitzer/MIPS 24 μm samples selected at z= 1, as observed 24 μm emission originates at rest-frame 12 μm in sources at this redshift.

X-Ray Absorption, Nuclear Infrared Emission, and Dust Covering Factors of AGNs: Testing Unification Schemes

NASA Astrophysics Data System (ADS)

Mateos, S.; Carrera, F. J.; Alonso-Herrero, A.; Hernán-Caballero, A.; Barcons, X.; Asensio Ramos, A.; Watson, M. G.; Blain, A.; Caccianiga, A.; Ballo, L.; Braito, V.; Ramos Almeida, C.

2016-03-01

We present the distributions of the geometrical covering factors of the dusty tori (f2) of active galactic nuclei (AGNs) using an X-ray selected complete sample of 227 AGNs drawn from the Bright Ultra-hard XMM-Newton Survey. The AGNs have z from 0.05 to 1.7, 2-10 keV luminosities between 1042 and 1046 erg s-1, and Compton-thin X-ray absorption. Employing data from UKIDSS, 2MASS, and the Wide-field Infrared Survey Explorer in a previous work, we determined the rest-frame 1-20 μm continuum emission from the torus, which we model here with the clumpy torus models of Nenkova et al. Optically classified type 1 and type 2 AGNs are intrinsically different, with type 2 AGNs having, on average, tori with higher f2 than type 1 AGNs. Nevertheless, ˜20% of type 1 AGNs have tori with large covering factors, while ˜23%-28% of type 2 AGNs have tori with small covering factors. Low f2 are preferred at high AGN luminosities, as postulated by simple receding torus models, although for type 2 AGNs the effect is certainly small. f2 increases with the X-ray column density, which implies that dust extinction and X-ray absorption take place in material that share an overall geometry and most likely belong to the same structure, the putative torus. Based on our results, the viewing angle, AGN luminosity, and also f2 determine the optical appearance of an AGN and control the shape of the rest-frame ˜1-20 μm nuclear continuum emission. Thus, the torus geometrical covering factor is a key ingredient of unification schemes.

Fast-steering solutions for cubesat-scale optical communications

NASA Astrophysics Data System (ADS)

Kingsbury, R. W.; Nguyen, T.; Riesing, K.; Cahoy, K.

2017-11-01

We describe the design of a compact free-space optical communications module for use on a nanosatellite and present results from a detailed trade study to select an optical fine steering mechanism compatible with our stringent size, weight and power (SWaP) constraints. This mechanism is an integral component of the compact free-space optical communications system that is under development at the MIT Space Systems Laboratory [1]. The overall goal of this project is to develop a laser communications (lasercom) payload that fits within the SWaP constraints of a typical ``3U'' CubeSat. The SWaP constraints for the entire lasercom payload are 5 cm × 10 cm × 10 cm, 600 g and 10W. Although other efforts are underway to qualify MEMS deformable mirrors for use in CubeSats [2], there has been very little work towards qualifying tip-tilt MEMS mirrors [3]. Sec. II provides additional information on how the fast steering mechanism is used in our lasercom system. Performance requirements and desirable traits of the mechanism are given. In Sec. III we describe the various types of compact tip-tilt mirrors that are commercially available as well as the justification for selecting a MEMS-based device for our application. Sec. IV presents an analysis of the device's transfer function characteristics and ways of predicting this behavior that are suitable for use in the control processor. This analysis is based upon manufacturer-provided test data which was collected at standard room conditions. In the final section, we describe on-going work to build a testbed that will be used to measure device performance in a thermal chamber.

Homeostatic Presynaptic Plasticity Is Specifically Regulated by P/Q-type Ca2+ Channels at Mammalian Hippocampal Synapses.

PubMed

Jeans, Alexander F; van Heusden, Fran C; Al-Mubarak, Bashayer; Padamsey, Zahid; Emptage, Nigel J

2017-10-10

Voltage-dependent Ca 2+ channels (VGCC) represent the principal source of Ca 2+ ions driving evoked neurotransmitter release at presynaptic boutons. In mammals, presynaptic Ca 2+ influx is mediated mainly via P/Q-type and N-type VGCC, which differ in their properties. Changes in their relative contributions tune neurotransmission both during development and in Hebbian plasticity. However, whether this represents a functional motif also present in other forms of activity-dependent regulation is unknown. Here, we study the role of VGCC in homeostatic plasticity (HSP) in mammalian hippocampal neurons using optical techniques. We find that changes in evoked Ca 2+ currents specifically through P/Q-type, but not N-type, VGCC mediate bidirectional homeostatic regulation of both neurotransmitter release efficacy and the size of the major synaptic vesicle pools. Selective dependence of HSP on P/Q-type VGCC in mammalian terminals has important implications for phenotypes associated with P/Q-type channelopathies, including migraine and epilepsy. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

Optical bio-sniffer for methyl mercaptan in halitosis.

PubMed

Mitsubayashi, Kohji; Minamide, Takeshi; Otsuka, Kimio; Kudo, Hiroyuki; Saito, Hirokazu

2006-07-28

An optical bio-sniffer for methyl mercaptan (MM) one of major odorous chemicals in halitosis (bad breath) was constructed by immobilizing monoamine oxidase type A (MAO-A) onto a tip of a fiber optic oxygen sensor (od: 1.59 mm) with an oxygen sensitive ruthenium organic complex (excitation: 470 nm, fluorescent: 600 nm). A flow cell for circulating buffer solution was applied to rinse and clean the tip of the device like nasal mucosa. In order to amplify the bio-sniffer output, a substrate regeneration cycle caused by coupling MAO-A with l-ascorbic acid (AsA) as reducing reaction with reagent system was applied to the sensor system. After evaluating the sensor characteristics using a gas flow measurement system with a gas generator, the optical bio-sniffer was applied to expired gases from healthy male volunteers for halitosis analysis as a physiological application. The optical bio-sniffer was applied to detect the oxygen consumption induced by MAO-A enzymatic reaction (and AsA chemical reduction) with gaseous MM application. The bio-sniffer was calibrated against MM vapor from 8.7 to 11500 ppb with correlation coefficient of 0.977, including a MM threshold (200 ppb) of pathologic halitosis and the human sense of smell level 3.5 (10.0 ppb), with good gas-selectivity based on the MAO-A substrate specificity. As the result of the physiological application, the optical bio-sniffer could successfully monitor the MM level change in breath samples during daytime, which is consistent with the previously reported results.

Competition between SFG and two SHGs in broadband type-I QPM

NASA Astrophysics Data System (ADS)

Dang, Weirui; Chen, Yuping; Gong, Mingjun; Chen, Xianfeng

2013-03-01

In this paper, we have studied the characteristics of second-order nonlinear interactions with band-overlapped type-I quasi-phase-matching (QPM) second harmonic generation (SHG) and sum-frequency generation (SFG), and predicted a blue-shift with a band-narrowing of their bands and a sunken response in the SFG curve, which are due to the phase-matching-dependent competition between band-overlapped SHG and SFG processes. This prediction is then verified by the experiment in an 18-mm-long bulk MgO-doped periodically poled lithium niobate crystal (MgO:PPLN) and may provide the candidate solution to output controlling for flexible broadcast wavelength conversion, channel-selective wavelength conversion and all-optical logic gates by cascaded QPM second-order nonlinear processes.

Figures of merit for self-beating filtered microwave photonic systems.

PubMed

Pérez, Daniel; Gasulla, Ivana; Capmany, José; Fandiño, Javier S; Muñoz, Pascual; Alavi, Hossein

2016-05-02

We present a model to compute the figures of merit of self-beating Microwave Photonic systems, a novel class of systems that work on a self-homodyne fashion by sharing the same laser source for information bearing and local oscillator tasks. General and simplified expressions are given and, as an example, we have considered their application to the design of a tunable RF MWP BS/UE front end for band selection, based on a Chebyshev Type-II optical filter. The applicability and usefulness of the model are also discussed.

Design of a laboratory study of contaminant film darkening in space

NASA Astrophysics Data System (ADS)

Judeikis, H. S.; Arnold, G. S.; Hill, M.; Young Owl, R. C.; Hall, D. F.

This paper reports the philosophy, design, and initial results of a program aimed at improving control of the optical effects of contamination in the design of a spacecraft. The types of basic data needed to produce criteria for the selection of spacecraft material based on the effects of the contaminant films they produce are discussed. The results of a spacecraft nonmetallic materials list analysis and radiation sensitivity estimates are presented. A rationale is given for simulation analysis of the potential effects of the geosynchronous environment on organic contaminant films.

Practical photochemistry: General considerations

NASA Astrophysics Data System (ADS)

Hutchison, J.

1986-05-01

Practical aspects of laboratory scale preparative photochemistry are discussed under the headings of: (1) lamps: dimensions, power ratings, spectral distributions and output intensities of different lamp types; (2) the reaction mixture: factors involved in establishing the most suitable wavelength region to use to carry out a particular reaction; the selection of the appropriate solvents, filters, and glassware; concentration of the photoactive component; (3) preparative photoreactions: immersion well, falling film, external irradiation and elliptical configurations; (4) apparatus for quantitative work: carousel and optical bench arrangements; (5) hazards: effects of ultraviolet radiation on eyes and skin and precautions to be taken.

Topological insulator infrared pseudo-bolometer with polarization sensitivity

DOEpatents

Sharma, Peter Anand

2017-10-25

Topological insulators can be utilized in a new type of infrared photodetector that is intrinsically sensitive to the polarization of incident light and static magnetic fields. The detector isolates single topological insulator surfaces and allows light collection and exposure to static magnetic fields. The wavelength range of interest is between 750 nm and about 100 microns. This detector eliminates the need for external polarization selective optics. Polarization sensitive infrared photodetectors are useful for optoelectronics applications, such as light detection in environments with low visibility in the visible wavelength regime.

Ultrafast optical technique for the characterization of altered materials

DOEpatents

Maris, H.J.

1998-01-06

Disclosed herein is a method and a system for non-destructively examining a semiconductor sample having at least one localized region underlying a surface through into which a selected chemical species has been implanted or diffused. A first step induces at least one transient time-varying change in optical constants of the sample at a location at or near to a surface of the sample. A second step measures a response of the sample to an optical probe beam, either pulsed or continuous wave, at least during a time that the optical constants are varying. A third step associates the measured response with at least one of chemical species concentration, chemical species type, implant energy, a presence or absence of an introduced chemical species region at the location, and a presence or absence of implant-related damage. The method and apparatus in accordance with this invention can be employed in conjunction with a measurement of one or more of the following effects arising from a time-dependent change in the optical constants of the sample due to the application of at least one pump pulse: (a) a change in reflected intensity; (b) a change in transmitted intensity; (c) a change in a polarization state of the reflected and/or transmitted light; (d) a change in the optical phase of the reflected and/or transmitted light; (e) a change in direction of the reflected and/or transmitted light; and (f) a change in optical path length between the sample`s surface and a detector. 22 figs.

Type II Supernova Light Curves and Spectra from the CfA

NASA Astrophysics Data System (ADS)

Hicken, Malcolm; Friedman, Andrew S.; Blondin, Stephane; Challis, Peter; Berlind, Perry; Calkins, Mike; Esquerdo, Gil; Matheson, Thomas; Modjaz, Maryam; Rest, Armin; Kirshner, Robert P.

2017-11-01

We present multiband photometry of 60 spectroscopically confirmed supernovae (SNe): 39 SNe II/IIP, 19 IIn, 1 IIb, and 1 that was originally classified as a IIn but later as a Ibn. Of these, 46 have only optical photometry, 6 have only near-infrared (NIR) photometry, and 8 have both optical and NIR. The median redshift of the sample is 0.016. We also present 195 optical spectra for 48 of the 60 SN. There are 26 optical and 2 NIR light curves of SNe II/IIP with redshifts z> 0.01, some of which may give rise to useful distances for cosmological applications. All photometry was obtained between 2000 and 2011 at the Fred Lawrence Whipple Observatory (FLWO), via the 1.2 m and 1.3 m PAIRITEL telescopes for the optical and NIR, respectively. Each SN was observed in a subset of the u\\prime {UBVRIr}\\prime I\\prime {{JHK}}s bands. There are a total of 2932 optical and 816 NIR light curve points. Optical spectra were obtained using the FLWO 1.5 m Tillinghast telescope with the FAST spectrograph and the MMT Telescope with the Blue Channel Spectrograph. Our photometry is in reasonable agreement with select samples from the literature: two-thirds of our star sequences have average V offsets within ±0.02 mag and roughly three-quarters of our light curves have average differences within ±0.04 mag. The data from this work and the literature will provide insight into SN II explosions, help with developing methods for photometric SN classification, and contribute to their use as cosmological distance indicators.

Ultrafast optical technique for the characterization of altered materials

DOEpatents

Maris, Humphrey J.

1998-01-01

Disclosed herein is a method and a system for non-destructively examining a semiconductor sample (30) having at least one localized region underlying a surface (30a) through into which a selected chemical species has been implanted or diffused. A first step induces at least one transient time-varying change in optical constants of the sample at a location at or near to a surface of the sample. A second step measures a response of the sample to an optical probe beam, either pulsed or continuous wave, at least during a time that the optical constants are varying. A third step associates the measured response with at least one of chemical species concentration, chemical species type, implant energy, a presence or absence of an introduced chemical species region at the location, and a presence or absence of implant-related damage. The method and apparatus in accordance with this invention can be employed in conjunction with a measurement of one or more of the following effects arising from a time-dependent change in the optical constants of the sample due to the application of at least one pump pulse: (a) a change in reflected intensity; (b) a change in transmitted intensity; (c) a change in a polarization state of the reflected and/or transmitted light; (d) a change in the optical phase of the reflected and/or transmitted light; (e) a change in direction of the reflected and/or transmitted light; and (f) a change in optical path length between the sample's surface and a detector.

Fluoride-selective optical sensor based on aluminum(III)-octaethylporphyrin in thin polymeric film: further characterization and practical application.

PubMed

Badr, Ibrahim H A; Meyerhoff, Mark E

2005-10-15

More detailed analytical studies of a new fluoride-selective optical sensor based on the use of aluminum(III)-octaethylporphyrin and a lipophilic pH indicator (4',5'-dibromofluorescein octadecyl ester; ETH-7075) within a thin plasticized poly(vinyl chloride) film are reported. The sensor exhibits extraordinary optical selectivity for fluoride over a wide range of other anions, including anions with far more positive free energies of hydration (e.g., perchlorate, thiocyanate, nitrate, etc.). UV-visible spectrophotometric studies of the sensing films indicate that fluoride interacts with the Al(III) center of the porphyrin structure, yielding both a change in the Soret band lambda(max) of the porphyrin and a change in the protonation state of the pH indicator within the film. The same change in spectral properties of the metalloporphyrin occurs in the absence of added pH indicator or with added tetraphenylborate derivative anionic sites, but optical responses to fluoride in these cases are shown to be irreversible. The presence of the pH indicator and the simultaneous fluoride/proton coextraction equilibrium chemistry is shown to greatly enhance the reversibility of fluoride binding to the Al(III) porphyrin. Optical response toward fluoride can be observed in the range of 0.1 microM-1.6 mM. Optical selectivity coefficients of <10(-6) for common anions (e.g., sulfate, chloride, nitrate, etc.) and <10(-4) for perchlorate and thiocyanate are obtained. Measurements of fluoride in drinking water via the new optical sensor are shown to correlate well with values obtained for the same samples using a classical LaF3-based fluoride ion-selective electrode method.

Fluoride Selective Optical Sensor Based on Aluminum(III)-Octaethylporphyrin in Thin Polymeric Film: Further Characterization and Practical Application

PubMed Central

Badr, Ibrahim H. A.; Meyerhoff, Mark E.

2008-01-01

More detailed analytical studies of a new fluoride selective optical sensor based on the use of aluminum(III)-octaethylporphyrin and a lipophilic pH indicator (4′,5′-dibromofluorescein octadecyl ester; ETH-7075) within a thin plasticized poly(vinyl chloride) film are reported. The sensor exhibits extraordinary optical selectivity for fluoride over a wide range of other anions, including anions with far more positive free energies of hydration (e.g., perchlorate, thiocyanate, nitrate, etc.). UV-VIS spectrophotometric studies of the sensing films indicate that fluoride interacts with the Al(III) center of the porphyrin structure, yielding both a change in the Soret band λmax of the porphyrin as well as a change in the protonation state of the pH indicator within the film. The same change in spectral properties of the metalloporphyrin occurs in the absence of added pH indicator or with added tetraphenylborate derivative anionic sites, but optical responses to fluoride in these cases are shown to be irreversible. The presence of the pH indicator and the simultaneous fluoride/proton coextraction equilibrium chemistry is shown to greatly enhance the reversibility of fluoride binding to the Al(III) porphyrin. Optical response toward fluoride can be observed in the range of 0.1 μM to 1.6 mM. Optical selectivity coefficients of < 10−6 for common anions (e.g., sulfate, chloride, nitrate etc.) and < 10−4 for perchlorate and thiocyanate are obtained. Measurements of fluoride in drinking water via the new optical sensor are shown to correlate well with values obtained for the same samples using a classical LaF3 based fluoride ion-selective electrode method. PMID:16223262

Prism-type holographic optical element design and verification for the blue-light small-form-factor optical pickup head.

PubMed

Shih, Hsi-Fu; Chiu, Yi; Cheng, Stone; Lee, Yuan-Chin; Lu, Chun-Shin; Chen, Yung-Chih; Chiou, Jin-Chern

2012-08-20

This paper presents the prism-type holographic optical element (PT-HOE) design for a small-form-factor (SFF) optical pickup head (OPH). The surface of the PT-HOE was simulated by three steps of optimization and generated by binary optics. Its grating pattern was fabricated on the inclined plane of a microprism by using the standard photolithography and specific dicing procedures. The optical characteristics of the device were verified. Based on the virtual image method, the SFF-OPH with the device was assembled and realized.

Infrared wavelength dependence of leaky mode losses and steady state distribution in W-type glass optical fibers

NASA Astrophysics Data System (ADS)

Djordjevich, Alexandar; Simović, Ana; Savović, Svetislav; Drljača, Branko

2018-07-01

Infrared wavelength dependence of leaky mode losses and steady state distribution (SSD) in W-type glass optical fibers (doubly clad fibers with three layers) is investigated in this paper for parametrically varied depths and widths of the fiber's intermediate optical layer. This enables a tailoring of configuration of the W-type fiber to suit an application at hand. We have shown that the proposed W-type fiber has better transmission characteristics at longer infrared wavelengths.

Rugged, Portable, Real-Time Optical Gaseous Analyzer for Hydrogen Fluoride

NASA Technical Reports Server (NTRS)

Pilgrim, Jeffrey; Gonzales, Paula

2012-01-01

Hydrogen fluoride (HF) is a primary evolved combustion product of fluorinated and perfluorinated hydrocarbons. HF is produced during combustion by the presence of impurities and hydrogen- containing polymers including polyimides. This effect is especially dangerous in closed occupied volumes like spacecraft and submarines. In these systems, combinations of perfluorinated hydrocarbons and polyimides are used for insulating wiring. HF is both highly toxic and short-lived in closed environments due to its reactivity. The high reactivity also makes HF sampling problematic. An infrared optical sensor can detect promptly evolving HF with minimal sampling requirements, while providing both high sensitivity and high specificity. A rugged optical path length enhancement architecture enables both high HF sensitivity and rapid environmental sampling with minimal gaseous contact with the low-reactivity sensor surfaces. The inert optical sample cell, combined with infrared semiconductor lasers, is joined with an analog and digital electronic control architecture that allows for ruggedness and compactness. The combination provides both portability and battery operation on a simple camcorder battery for up to eight hours. Optical detection of gaseous HF is confounded by the need for rapid sampling with minimal contact between the sensor and the environmental sample. A sensor is required that must simultaneously provide the required sub-parts-permillion detection limits, but with the high specificity and selectivity expected of optical absorption techniques. It should also be rugged and compact for compatibility with operation onboard spacecraft and submarines. A new optical cell has been developed for which environmental sampling is accomplished by simply traversing the few mm-thick cell walls into an open volume where the measurement is made. A small, low-power fan or vacuum pump may be used to push or pull the gaseous sample into the sample volume for a response time of a few seconds. The optical cell simultaneously provides for an enhanced optical interaction path length between the environmental sample and the infrared laser. Further, the optical cell itself is comprised of inert materials that render it immune to attack by HF. In some cases, the sensor may be configured so that the optoelectronic devices themselves are protected and isolated from HF by the optical cell. The optical sample cell is combined with custom-developed analog and digital control electronics that provide rugged, compact operation on a platform that can run on a camcorder battery. The sensor is inert with respect to acidic gases like HF, while providing the required sensitivity, selectivity, and response time. Certain types of combustion events evolve copious amounts of HF, very little of other gases typically associated with combustion (e.g., carbon monoxide), and very low levels of aerosols and particulates (which confound traditional smoke detectors). The new sensor platform could warn occupants early enough to take the necessary countermeasures.

Meeting the Cool Neighbors. XII. An Optically Anchored Analysis of the Near-infrared Spectra of L Dwarfs

NASA Astrophysics Data System (ADS)

Cruz, Kelle L.; Núñez, Alejandro; Burgasser, Adam J.; Abrahams, Ellianna; Rice, Emily L.; Reid, I. Neill; Looper, Dagny

2018-01-01

Discrepancies between competing optical and near-infrared (NIR) spectral typing systems for L dwarfs have motivated us to search for a classification scheme that ties the optical and NIR schemes together, and addresses complexities in the spectral morphology. We use new and extant optical and NIR spectra to compile a sample of 171 L dwarfs, including 27 low-gravity β and γ objects, with spectral coverage from 0.6–2.4 μm. We present 155 new low-resolution NIR spectra and 19 new optical spectra. We utilize a method for analyzing NIR spectra that partially removes the broad-band spectral slope and reveals similarities in the absorption features between objects of the same optical spectral type. Using the optical spectra as an anchor, we generate near-infrared spectral average templates for L0–L8, L0–L4γ, and L0–L1β type dwarfs. These templates reveal that NIR spectral morphologies are correlated with the optical types. They also show the range of spectral morphologies spanned by each spectral type. We compare low-gravity and field-gravity templates to provide recommendations on the minimum required observations for credibly classifying low-gravity spectra using low-resolution NIR data. We use the templates to evaluate the existing NIR spectral standards and propose new ones where appropriate. Finally, we build on the work of Kirkpatrick et al. to provide a spectral typing method that is tied to the optical and can be used when only H or K band data are available. The methods we present here provide resolutions to several long-standing issues with classifying L dwarf spectra and could also be the foundation for a spectral classification scheme for cloudy exoplanets.

Mini Survey of SDSS [OIII] AGN with Swift: Testing the Hypothesis that L(sub [OIII]) Traces AGN Luminosity

NASA Technical Reports Server (NTRS)

2007-01-01

The number of AGN and their luminosity distribution are crucial parameters for our understanding of the AGN phenomenon. Recent work strongly suggests every massive galaxy has a central black hole. However most of these objects either are not radiating or have been very difficult to detect We are now in the era of large surveys, and the luminosity function (LF] of AGN has been estimated in various ways. In the X-ray band. Chandra and XMM surveys have revealed that the LF of hard X-ray selected AGN shows a strong luminosity-dependent evolution with a dramatic break towards low L(sub x) (at all z). This is seen for all types of AGN, but is stronger for the broad-line objects. In sharp contrast, the local LF of optically-selected samples shows no such break and no differences between narrow and broad-line objects. If as been suggested, hard X ray and optical emission line can both can be fair indicators of AGN activity, it is important to first understand how reliable these characteristics are if we hope to understand the apparent discrepancy in the LFs.

Tune-out wavelengths and landscape-modulated polarizabilities of alkali-metal Rydberg atoms in infrared optical lattices

NASA Astrophysics Data System (ADS)

Topcu, Turker; Derevianko, Andrei

2013-11-01

Intensity-modulated optical lattice potentials can change sign for an alkali-metal Rydberg atom, and the atoms are not always attracted to intensity minima in optical lattices with wavelengths near the CO2 laser band. Here we demonstrate that such IR lattices can be tuned so that the trapping potential experienced by the Rydberg atom can be made to vanish for atoms in “targeted” Rydberg states. Such state-selective trapping of Rydberg atoms can be useful in controlled cold Rydberg collisions, cooling Rydberg states, and species-selective trapping and transport of Rydberg atoms in optical lattices. We tabulate wavelengths at which the trapping potential vanishes for the ns, np, and nd Rydberg states of Na and Rb atoms and discuss advantages of using such optical lattices for state-selective trapping of Rydberg atoms. We also develop exact analytical expressions for the lattice-induced polarizability for the mz=0 Rydberg states and derive an accurate formula predicting tune-out wavelengths at which the optical trapping potential becomes invisible to Rydberg atoms in targeted l=0 states.

Soft exfoliation of 2D SnO with size-dependent optical properties

NASA Astrophysics Data System (ADS)

Singh, Mandeep; Della Gaspera, Enrico; Ahmed, Taimur; Walia, Sumeet; Ramanathan, Rajesh; van Embden, Joel; Mayes, Edwin; Bansal, Vipul

2017-06-01

Two-dimensional (2D) materials have recently gained unprecedented attention as potential candidates for next-generation (opto)electronic devices due to their fascinating optical and electrical properties. Tin monoxide, SnO, is an important p-type semiconductor with applications across photocatalysis (water splitting) and electronics (transistors). However, despite its potential in several important technological applications, SnO remains underexplored in its 2D form. Here we present a soft exfoliation strategy to produce 2D SnO nanosheets with tunable optical and electrical properties. Our approach involves the initial synthesis of layered SnO microspheres, which are readily exfoliated through a low-power sonication step to form high quality SnO nanosheets. We demonstrate that the properties of 2D SnO are strongly dependent on its dimensions. As verified through optical absorption and photoluminescence studies, a strong size-dependent quantum confinement effect in 2D SnO leads to substantial variation in its optical and electrical properties. This results in a remarkable (>1 eV) band gap widening in atomically thin SnO. Through photoconductivity measurements, we further validate a strong correlation between the quantum-confined properties of 2D SnO and the selective photoresponse of atomically thin sheets in the high energy UV light. Such tunable semiconducting properties of 2D SnO could be exploited for a variety of applications including photocatalysis, photovoltaics and optoelectronics in general.

Low-cost, high-precision micro-lensed optical fiber providing deep-micrometer to deep-nanometer-level light focusing.

PubMed

Wen, Sy-Bor; Sundaram, Vijay M; McBride, Daniel; Yang, Yu

2016-04-15

A new type of micro-lensed optical fiber through stacking appropriate high-refractive microspheres at designed locations with respect to the cleaved end of an optical fiber is numerically and experimentally demonstrated. This new type of micro-lensed optical fiber can be precisely constructed with low cost and high speed. Deep micrometer-scale and submicrometer-scale far-field light spots can be achieved when the optical fibers are multimode and single mode, respectively. By placing an appropriate teardrop dielectric nanoscale scatterer at the far-field spot of this new type of micro-lensed optical fiber, a deep-nanometer near-field spot can also be generated with high intensity and minimum joule heating, which is valuable in high-speed, high-resolution, and high-power nanoscale detection compared with traditional near-field optical fibers containing a significant portion of metallic material.

Optical interconnect technologies for high-bandwidth ICT systems

NASA Astrophysics Data System (ADS)

Chujo, Norio; Takai, Toshiaki; Mizushima, Akiko; Arimoto, Hideo; Matsuoka, Yasunobu; Yamashita, Hiroki; Matsushima, Naoki

2016-03-01

The bandwidth of information and communication technology (ICT) systems is increasing and is predicted to reach more than 10 Tb/s. However, an electrical interconnect cannot achieve such bandwidth because of its density limits. To solve this problem, we propose two types of high-density optical fiber wiring for backplanes and circuit boards such as interface boards and switch boards. One type uses routed ribbon fiber in a circuit board because it has the ability to be formed into complex shapes to avoid interfering with the LSI and electrical components on the board. The backplane is required to exhibit high density and flexibility, so the second type uses loose fiber. We developed a 9.6-Tb/s optical interconnect demonstration system using embedded optical modules, optical backplane, and optical connector in a network apparatus chassis. We achieved 25-Gb/s transmission between FPGAs via the optical backplane.

Cross Matching as Strategy to Find Radio Stars

NASA Astrophysics Data System (ADS)

Christian, Tiffany; Kimball, Amy

2018-01-01

Using cross-matching between the FIRST (20cm) and GPS1 (optical) catalogs, we identified possible radio star candidates. This is an extension of earlier work by Kimball et al. (2009), who sought to identify radiostar candidates by cross-matching the FIRST (radio)and SDSS (optical) catalogs, but did not include the consideration of stellar proper motions. We used proper motions from GPS1 to match with FIRST radio sources; the region of sky where they overlap contains ~900,000 FIRST sources and several million GPS1 sources. We used WISE near-infrared and PanSTARRS optical information to identify matches that have stellar colors. Our selection constraints identified 6 stars (spectroscopically confirmed) as radio star candidates. They are faint in the radio (<1 mJy) indicating we may be searching at the limits of the radio survey. Other candidates had no spectral confirmation or object type identification in SIMBAD, which would make them ideal for follow up radio observations. However, random analysis indicated that many other possible candidates were random associations, which may also be true for these 6 stars.

Progress towards measuring the Rydberg Constant Using Circular Rydberg Atoms in an Intensity-Modulated Optical Lattice

NASA Astrophysics Data System (ADS)

Ramos, Andira; Moore, Kaitlin; Raithel, Georg

2015-05-01

Recent significant disagreement with the previously established size of the proton demonstrates a need to reconsider the current value of the Rydberg constant, the effects of the nuclear charge distribution and QED in hydrogen-like atoms. An experiment is in progress to obtain a measurement of the Rydberg constant by studying circular Rydberg atoms, which exhibit very small QED shifts and electron wavefunctions which do not overlap with the nucleus. Cold Rydberg atoms are trapped using a ponderomotive potential. To drive the transitions, a novel type of spectroscopy is used which utilizes an optical-lattice field that is intensity-modulated at the frequencies of atomic transitions. The method is free of typical spectroscopic selection rules and has been shown to drive transitions up to fifth order. Combined with optical Rydberg-atom trapping, the method enables the measurement of narrow, sub-THz transitions between long-lived circular Rydberg levels. Energy shifts affecting this precision measurement will also be discussed. This work is suported by NSF, NIST and NASA grants.

Rapid evaluation of high-performance systems

NASA Astrophysics Data System (ADS)

Forbes, G. W.; Ruoff, J.

2017-11-01

System assessment for design often involves averages, such as rms wavefront error, that are estimated by ray tracing through a sample of points within the pupil. Novel general-purpose sampling and weighting schemes are presented and it is also shown that optical design can benefit from tailored versions of these schemes. It turns out that the type of Gaussian quadrature that has long been recognized for efficiency in this domain requires about 40-50% more ray tracing to attain comparable accuracy to generic versions of the new schemes. Even greater efficiency gains can be won, however, by tailoring such sampling schemes to the optical context where azimuthal variation in the wavefront is generally weaker than the radial variation. These new schemes are special cases of what is known in the mathematical world as cubature. Our initial results also led to the consideration of simpler sampling configurations that approximate the newfound cubature schemes. We report on the practical application of a selection of such schemes and make observations that aid in the discovery of novel cubature schemes relevant to optical design of systems with circular pupils.

Fresnel zone plate with apodized aperture for hard X-ray Gaussian beam optics.

PubMed

Takeuchi, Akihisa; Uesugi, Kentaro; Suzuki, Yoshio; Itabashi, Seiichi; Oda, Masatoshi

2017-05-01

Fresnel zone plates with apodized apertures [apodization FZPs (A-FZPs)] have been developed to realise Gaussian beam optics in the hard X-ray region. The designed zone depth of A-FZPs gradually decreases from the center to peripheral regions. Such a zone structure forms a Gaussian-like smooth-shouldered aperture function which optically behaves as an apodization filter and produces a Gaussian-like focusing spot profile. Optical properties of two types of A-FZP, i.e. a circular type and a one-dimensional type, have been evaluated by using a microbeam knife-edge scan test, and have been carefully compared with those of normal FZP optics. Advantages of using A-FZPs are introduced.

[Treatment options for nystagmus].

PubMed

Tegetmeyer, H

2015-02-01

The goal of treatment for nystagmus is to reduce or to abolish the typical symptoms associated with nystagmus. These are (i) reduction of visual acuity (and amblyopia in infantile nystagmus), (ii) abnormal head posture (with possible secondary changes of cervical spine) and (iii) oscillopsia (often connected with vertigo and disorders of gait and orientation). Treatment strategies include pharmacological treatment, surgical therapy and optical devices. Choice of treatment depends on the type of nystagmus and its characteristics. The following surgical procedures were successfully used as treatment of selected symptoms: (i) unilateral recess-resect surgery of the dominant eye in infantile esotropia with latent nystagmus for the relief of abnormal head posture, (ii) Kestenbaum operation of both eyes in infantile nystagmus syndrome with excentric null zone and abnormal head posture, (iii) recess-resect surgery to produce artificial exophoria in infantile nystagmus syndrome. PHARMACOLOGICAL TREATMENT: Depending on the pathophysiology of different types of nystagmus, several drugs were effective in clinical application (off-label use): (i) gabapentin (non-selective GABAergic and anti-glutamatergic effect): up to 2400 mg/d in infantile nystagmus, acquired pendular nystagmus and oculopalatal tremor, (ii) nemantine (anti-glutamatergic effect): dosage up to 40 mg/d in infantile nystagmus, also in acquired pendular nystagmus and oculopalatal tremor, (iii) baclofen (GABA-B-receptor agonist): 3 × 5-10 mg/d in periodic alternating nystagmus and in upbeat nystagmus, (iv) 4-aminopyridine (non-selective blocker of voltage-gated potassium channels): 3 × 5 mg/d or 1-2 × 10 mg Fampridin in downbeat nystagmus and upbeat nystagmus, (v) acetazolamide (carbonic anhydrase inhibitor): in hereditary episodic ataxia type 2. OPTICAL DEVICES: (i) Contact lenses are used in infantile nystagmus in order to overcome negative effects of eye glasses in abnormal head posture, lateral gaze, and higher refractive errors, (ii) spectacle prisms are useful to induce an artificial exophoria (base-out prisms) or to shift an excentric null zone (base in direction of head posture) of infantile nystagmus with abnormal head posture, (iii) low vision aids may be necessary and should be prescribed according to magnification requirements. Georg Thieme Verlag KG Stuttgart · New York.

SODI-COLLOID (Selectable Optical Diagnostics Instrument - Colloid)

NASA Image and Video Library

2011-10-17

ISS029-E-027431 (17 Oct. 2011) --- In the International Space Station?s Destiny laboratory, Japan Aerospace Exploration Agency astronaut Satoshi Furukawa, Expedition 29 flight engineer, activates the Microgravity Science Glovebox (MSG) in preparation for work with the Selectable Optical Diagnostics Instrument ? Colloid (SODI-COLLOID) hardware.

SODI-COLLOID (Selectable Optical Diagnostics Instrument - Colloid)

NASA Image and Video Library

2011-10-17

ISS029-E-027435 (17 Oct. 2011) --- In the International Space Station?s Destiny laboratory, Japan Aerospace Exploration Agency astronaut Satoshi Furukawa, Expedition 29 flight engineer, activates the Microgravity Science Glovebox (MSG) in preparation for work with the Selectable Optical Diagnostics Instrument ? Colloid (SODI-COLLOID) hardware.

Isotopologue-selective excitation studied via optical-optical double resonance using the E3 Σ1+(63S1) ←A3Π0+(53P1) ←X1Σ0+(51S0) transitions in CdAr and CdKr van der Waals complexes

NASA Astrophysics Data System (ADS)

Urbańczyk, T.; Dudek, J.; Koperski, J.

2018-06-01

A method of experimental selection of molecular isotopologues using optical-optical double resonance (OODR) scheme and supersonic beam source of van der Waals (vdW) complexes is presented. Due to an appropriately large isotopic shift, the proper choice of a wavenumber of a sufficiently narrowband laser in the first transition of OODR scheme can lead to a selective isotopologue excitation to the intermediate state. Thanks to this approach, it is possible to select some of the isotopologues which subsequently give a contribution to laser induced fluorescence (LIF) signal originated from the final state of OODR. In this article, results of tests of the proposed method that employs the E3 Σ1+ ←A3Π0+ ←X1Σ0+ transitions in two vdW complexes, CdKr and CdAr, are presented and analysed.

Highly efficient all-dielectric optical tensor impedance metasurfaces for chiral polarization control.

PubMed

Kim, Minseok; Eleftheriades, George V

2016-10-15

We propose a highly efficient (nearly lossless and impedance-matched) all-dielectric optical tensor impedance metasurface that mimics chiral effects at optical wavelengths. By cascading an array of rotated crossed silicon nanoblocks, we realize chiral optical tensor impedance metasurfaces that operate as circular polarization selective surfaces. Their efficiencies are maximized through a nonlinear numerical optimization process in which the tensor impedance metasurfaces are modeled via multi-conductor transmission line theory. From rigorous full-wave simulations that include all material losses, we show field transmission efficiencies of 94% for right- and left-handed circular polarization selective surfaces at 800 nm.

Optical-Correlator Neural Network Based On Neocognitron

NASA Technical Reports Server (NTRS)

Chao, Tien-Hsin; Stoner, William W.

1994-01-01

Multichannel optical correlator implements shift-invariant, high-discrimination pattern-recognizing neural network based on paradigm of neocognitron. Selected as basic building block of this neural network because invariance under shifts is inherent advantage of Fourier optics included in optical correlators in general. Neocognitron is conceptual electronic neural-network model for recognition of visual patterns. Multilayer processing achieved by iteratively feeding back output of feature correlator to input spatial light modulator and updating Fourier filters. Neural network trained by use of characteristic features extracted from target images. Multichannel implementation enables parallel processing of large number of selected features.

Mode-selective mapping and control of vectorial nonlinear-optical processes in multimode photonic-crystal fibers.

PubMed

Hu, Ming-Lie; Wang, Ching-Yue; Song, You-Jian; Li, Yan-Feng; Chai, Lu; Serebryannikov, Evgenii; Zheltikov, Aleksei

2006-02-06

We demonstrate an experimental technique that allows a mapping of vectorial nonlinear-optical processes in multimode photonic-crystal fibers (PCFs). Spatial and polarization modes of PCFs are selectively excited in this technique by varying the tilt angle of the input beam and rotating the polarization of the input field. Intensity spectra of the PCF output plotted as a function of the input field power and polarization then yield mode-resolved maps of nonlinear-optical interactions in multimode PCFs, facilitating the analysis and control of nonlinear-optical transformations of ultrashort laser pulses in such fibers.

Investigation of the feasibility of optical diagnostic measurements at the exit of the SSME

NASA Technical Reports Server (NTRS)

Shirley, John A.; Boedeker, Laurence R.

1993-01-01

Under Contract NAS8-36861 sponsored by NASA Marshall Space Flight Center, the United Technologies Research Center is conducting an investigation of the feasibility of remote optical diagnostics to measure temperature, species concentration and velocity at the exit of the Space Shuttle Main Engine (SSME). This is a two phase study consisting of a conceptual design phase followed by a laboratory experimental investigation. The first task of the conceptual design studies is to screen and evaluate the techniques which can be used for the measurements. The second task is to select the most promising technique or techniques, if as expected, more than one type of measurement must be used to measure all the flow variables of interest. The third task is to examine in detail analytically the capabilities and limitations of the selected technique(s). The results of this study are described in the section of this report entitled Conceptual Design Investigations. The conceptual design studies identified spontaneous Raman scattering and photodissociative flow-tagging for measurements respectively of gas temperature and major species concentration and for velocity. These techniques and others that were considered are described in the section describing the conceptual design. The objective of the second phase of investigations was to investigate experimentally the techniques identified in the first phase. The first task of the experimental feasibility study is to design and assemble laboratory scale experimental apparatus to evaluate the best approaches for SSME exit optical diagnostics for temperature, species concentrations and velocity, as selected in the Phase I conceptual design study. The second task is to evaluate performance, investigate limitations, and establish actual diagnostic capabilities, accuracies and precision for the selected optical systems. The third task is to evaluate design requirements and system trade-offs of conceptual instruments. Spontaneous Raman scattering excited by a KrF excimer laser pulse was investigated for SSME exit plane temperature and major species concentration measurements. The relative concentrations of molecular hydrogen and water vapor would be determined by measuring the integrated Q-branch scattering signals through narrow bandpass filters in front of photomultipliers. The temperature would be determined by comparing the signal from a single hydrogen rotational Raman line to the total hydrogen Q-branch signal. The rotational Raman line would be isolated by a monochromator and detected with a PMT.

Contact Electrification of Individual Dielectric Microparticles Measured by Optical Tweezers in Air.

PubMed

Park, Haesung; LeBrun, Thomas W

2016-12-21

We measure charging of single dielectric microparticles after interaction with a glass substrate using optical tweezers to control the particle, measure its charge with a sensitivity of a few electrons, and precisely contact the particle with the substrate. Polystyrene (PS) microparticles adhered to the substrate can be selected based on size, shape, or optical properties and repeatedly loaded into the optical trap using a piezoelectric (PZT) transducer. Separation from the substrate leads to charge transfer through contact electrification. The charge on the trapped microparticles is measured from the response of the particle motion to a step excitation of a uniform electric field. The particle is then placed onto a target location of the substrate in a controlled manner. Thus, the triboelectric charging profile of the selected PS microparticle can be measured and controlled through repeated cycles of trap loading followed by charge measurement. Reversible optical trap loading and manipulation of the selected particle leads to new capabilities to study and control successive and small changes in surface interactions.

Programmable optical processor chips: toward photonic RF filters with DSP-level flexibility and MHz-band selectivity

NASA Astrophysics Data System (ADS)

Xie, Yiwei; Geng, Zihan; Zhuang, Leimeng; Burla, Maurizio; Taddei, Caterina; Hoekman, Marcel; Leinse, Arne; Roeloffzen, Chris G. H.; Boller, Klaus-J.; Lowery, Arthur J.

2017-12-01

Integrated optical signal processors have been identified as a powerful engine for optical processing of microwave signals. They enable wideband and stable signal processing operations on miniaturized chips with ultimate control precision. As a promising application, such processors enables photonic implementations of reconfigurable radio frequency (RF) filters with wide design flexibility, large bandwidth, and high-frequency selectivity. This is a key technology for photonic-assisted RF front ends that opens a path to overcoming the bandwidth limitation of current digital electronics. Here, the recent progress of integrated optical signal processors for implementing such RF filters is reviewed. We highlight the use of a low-loss, high-index-contrast stoichiometric silicon nitride waveguide which promises to serve as a practical material platform for realizing high-performance optical signal processors and points toward photonic RF filters with digital signal processing (DSP)-level flexibility, hundreds-GHz bandwidth, MHz-band frequency selectivity, and full system integration on a chip scale.

Polarization Control with Plasmonic Antenna Tips: A Universal Approach to Optical Nanocrystallography and Vector-Field Imaging

NASA Astrophysics Data System (ADS)

Park, Kyoung-Duck; Raschke, Markus B.

2018-05-01

Controlling the propagation and polarization vectors in linear and nonlinear optical spectroscopy enables to probe the anisotropy of optical responses providing structural symmetry selective contrast in optical imaging. Here we present a novel tilted antenna-tip approach to control the optical vector-field by breaking the axial symmetry of the nano-probe in tip-enhanced near-field microscopy. This gives rise to a localized plasmonic antenna effect with significantly enhanced optical field vectors with control of both \\textit{in-plane} and \\textit{out-of-plane} components. We use the resulting vector-field specificity in the symmetry selective nonlinear optical response of second-harmonic generation (SHG) for a generalized approach to optical nano-crystallography and -imaging. In tip-enhanced SHG imaging of monolayer MoS$_2$ films and single-crystalline ferroelectric YMnO$_3$, we reveal nano-crystallographic details of domain boundaries and domain topology with enhanced sensitivity and nanoscale spatial resolution. The approach is applicable to any anisotropic linear and nonlinear optical response, and provides for optical nano-crystallographic imaging of molecular or quantum materials.

Contrasting aerosol optical and radiative properties between dust and urban haze episodes in megacities of Pakistan

NASA Astrophysics Data System (ADS)

Iftikhar, Muhammad; Alam, Khan; Sorooshian, Armin; Syed, Waqar Adil; Bibi, Samina; Bibi, Humera

2018-01-01

Satellite and ground based remote sensors provide vital information about aerosol optical and radiative properties. Analysis of aerosol optical and radiative properties during heavy aerosol loading events in Pakistan are limited and, therefore, require in-depth examination. This work examines aerosol properties and radiative forcing during Dust Episodes (DE) and Haze Episodes (HE) between 2010 and 2014 over mega cities of Pakistan (Karachi and Lahore). Episodes having the daily averaged values of Aerosol Optical Depth (AOD) exceeding 1 were selected. DE were associated with high AOD and low Ångström Exponent (AE) over Karachi and Lahore while high AOD and high AE values were associated with HE over Lahore. Aerosol volume size distributions (AVSD) exhibited a bimodal lognormal distribution with a noticeable coarse mode peak at a radius of 2.24 μm during DE, whereas a fine mode peak was prominent at a radius 0.25 μm during HE. The results reveal distinct differences between HE and DE for spectral profiles of several parameters including Single Scattering Albedo (SSA), ASYmmetry parameter (ASY), and the real and imaginary components of refractive index (RRI and IRI). The AOD-AE correlation revealed that dust was the dominant aerosol type during DE and that biomass burning and urban/industrial aerosol types were pronounced during HE. Aerosol radiative forcing (ARF) was estimated using the Santa Barbra DISORT Atmospheric Radiative Transfer (SBDART) model. Calculations revealed a negative ARF at the Top Of the Atmosphere (ARFTOA) and at the Bottom Of the Atmosphere (ARFBOA), with positive ARF within the Atmosphere (ARFATM) during both DE and HE over Karachi and Lahore. Furthermore, estimations of ARFATM by SBDART were shown to be in good agreement with values derived from AERONET data for DE and HE over Karachi and Lahore.

Classification of Human Retinal Microaneurysms Using Adaptive Optics Scanning Light Ophthalmoscope Fluorescein Angiography

PubMed Central

Dubow, Michael; Pinhas, Alexander; Shah, Nishit; Cooper, Robert F.; Gan, Alexander; Gentile, Ronald C.; Hendrix, Vernon; Sulai, Yusufu N.; Carroll, Joseph; Chui, Toco Y. P.; Walsh, Joseph B.; Weitz, Rishard; Dubra, Alfredo; Rosen, Richard B.

2014-01-01

Purpose. Microaneurysms (MAs) are considered a hallmark of retinal vascular disease, yet what little is known about them is mostly based upon histology, not clinical observation. Here, we use the recently developed adaptive optics scanning light ophthalmoscope (AOSLO) fluorescein angiography (FA) to image human MAs in vivo and to expand on previously described MA morphologic classification schemes. Methods. Patients with vascular retinopathies (diabetic, hypertensive, and branch and central retinal vein occlusion) were imaged with reflectance AOSLO and AOSLO FA. Ninety-three MAs, from 14 eyes, were imaged and classified according to appearance into six morphologic groups: focal bulge, saccular, fusiform, mixed, pedunculated, and irregular. The MA perimeter, area, and feret maximum and minimum were correlated to morphology and retinal pathology. Select MAs were imaged longitudinally in two eyes. Results. Adaptive optics scanning light ophthalmoscope fluorescein angiography imaging revealed microscopic features of MAs not appreciated on conventional images. Saccular MAs were most prevalent (47%). No association was found between the type of retinal pathology and MA morphology (P = 0.44). Pedunculated and irregular MAs were among the largest MAs with average areas of 4188 and 4116 μm2, respectively. Focal hypofluorescent regions were noted in 30% of MAs and were more likely to be associated with larger MAs (3086 vs. 1448 μm2, P = 0.0001). Conclusions. Retinal MAs can be classified in vivo into six different morphologic types, according to the geometry of their two-dimensional (2D) en face view. Adaptive optics scanning light ophthalmoscope fluorescein angiography imaging of MAs offers the possibility of studying microvascular change on a histologic scale, which may help our understanding of disease progression and treatment response. PMID:24425852

Nanodiamond in Colloidal Suspension: Electrophoresis; Other Observations

NASA Technical Reports Server (NTRS)

Meshik, A. P.; Pravdivtseva, O. V.; Hohenberg, C. M.

2002-01-01

Selective laser extraction has demonstrated that meteoritic diamonds may consist of subpopulations with different optical absorption properties, but it is not clear what makes them optically different. More work is needed to understand the mechanism for selective laser extraction. Additional information is contained in the original extended abstract.

VLA observations of a complete sample of extragalactic X-ray sources. II

NASA Technical Reports Server (NTRS)

Schild, R.; Zamorani, G.; Gioia, I. M.; Feigelson, E. D.; Maccacaro, T.

1983-01-01

A complete sample of 35 X-ray selected sources found with the Einstein Observatory has been observed with the Very Large Array at 6 cm to investigate the relationship between radio and X-ray emission in extragalactic objects. Detections include three active galactic nuclei (AGNs), two clusters or groups of galaxies, two individual galaxies, and two BL Lac objects. The frequency of radio emission in X-ray selected AGNs is compared with that of optically selected quasars using the integral radio-optical luminosity function. The result suggests that the probability for X-ray selected quasars to be radio sources is higher than for those optically selected. No obvious correlation is found in the sample between the richness of X-ray luminosity of the cluster and the presence of a galaxy with radio luminosity at 5 GHz larger than 10 to the 30th ergs/s/Hz.

Selective laser spectroscopy of molecules and ions in solids: a history, fundamentals and applications

NASA Astrophysics Data System (ADS)

Sapozhnikov, Michael

2018-03-01

A history of the development of selective laser spectroscopy is presented, beginning with a pioneering work by Yu. V. Denisov and V. A. Kizel in 1967, who were the first to demonstrate the possibility of removing the inhomogeneous broadening of luminescence spectra of impurity ions in glasses upon monochromatic resonance excitation. Selective excitation of optical centers can be achieved due to existence of zero-phonon transitions corresponding to narrow homogeneous zero-phonon lines in the spectra of impurity centers in solids, which are hidden in broad inhomogeneous optical bands upon usual nonselective excitation. The fundamentals of zero-phonon transition spectroscopy are considered and the mechanism of removing the inhomogeneous broadening of optical spectra of ions and molecules in crystals and amorphous solids under selective laser excitation of luminescence and persistent hole burning in absorption spectra is presented in detail. Various applications of selective laser spectroscopy for fundamental and applied studies are discussed.

Flamingos 2 Spectroscopy of Obscured and Unobscured Quasars

NASA Astrophysics Data System (ADS)

Ridgway, Susan; Lacy, Mark; Urrutia, Tanya; Petric, Andreea

2013-08-01

We will use Flamingos-2 to obtain spectra of luminous AGN and quasars selected in the mid-infrared. Mid-infrared selection is much less biased with respect to obscuration than optical and X-ray techniques, and hence allows for finding obscured (Type-2) quasars as well as Type-1 quasars. Our survey so far has been very successful and has provided an unique opportunity to construct luminosity functions for both Type-1 and Type-2 quasars selected in the same way and covering similar redshifts and luminosities. We have quantifed the change in the obscured fraction with luminosity and redshift for the first time, and find interesting indications that at high redshift the obscured fraction rises, consistent with models for the joint formation of the galaxy and black hole populations. Our samples are, however, still quite incomplete at low fluxes (and therefore lower luminosities at a given redshift), particularly in the southern hemisphere. Near-infrared spectroscopy, such as that we have previously obtained with NIRI at Gemini N, offers us the best possibility of bringing these southern samples to a reasonable completeness level, and will greatly increase the number of high z quasars in our sample. This will allow us to better judge our tantalizing initial results on the redshift evolution of the obscured fraction. In addition, these southern targets can be followed up with ALMA and GEMS/GSAOI to study the morphologies and star-formation properties of the hosts, allowing further exploration of the relationship between the formation of massive bulges and supermassive blackholes in the early universe.

Spectroscopic follow-up of variability-selected active galactic nuclei in the Chandra Deep Field South

NASA Astrophysics Data System (ADS)

Boutsia, K.; Leibundgut, B.; Trevese, D.; Vagnetti, F.

2009-04-01

Context: Supermassive black holes with masses of 10^5-109 M⊙ are believed to inhabit most, if not all, nuclear regions of galaxies, and both observational evidence and theoretical models suggest a scenario where galaxy and black hole evolution are tightly related. Luminous AGNs are usually selected by their non-stellar colours or their X-ray emission. Colour selection cannot be used to select low-luminosity AGNs, since their emission is dominated by the host galaxy. Objects with low X-ray to optical ratio escape even the deepest X-ray surveys performed so far. In a previous study we presented a sample of candidates selected through optical variability in the Chandra Deep Field South, where repeated optical observations were performed in the framework of the STRESS supernova survey. Aims: The analysis is devoted to breaking down the sample in AGNs, starburst galaxies, and low-ionisation narrow-emission line objects, to providing new information about the possible dependence of the emission mechanisms on nuclear luminosity and black-hole mass, and eventually studying the evolution in cosmic time of the different populations. Methods: We obtained new optical spectroscopy for a sample of variability selected candidates with the ESO NTT telescope. We analysed the new spectra, together with those existing in the literature and studied the distribution of the objects in U-B and B-V colours, optical and X-ray luminosity, and variability amplitude. Results: A large fraction (17/27) of the observed candidates are broad-line luminous AGNs, confirming the efficiency of variability in detecting quasars. We detect: i) extended objects which would have escaped the colour selection and ii) objects of very low X-ray to optical ratio, in a few cases without any X-ray detection at all. Several objects resulted to be narrow-emission line galaxies where variability indicates nuclear activity, while no emission lines were detected in others. Some of these galaxies have variability and X-ray to optical ratio close to active galactic nuclei, while others have much lower variability and X-ray to optical ratio. This result can be explained by the dilution of the nuclear light due to the host galaxy. Conclusions: Our results demonstrate the effectiveness of supernova search programmes to detect large samples of low-luminosity AGNs. A sizable fraction of the AGN in our variability sample had escaped X-ray detection (5/47) and/or colour selection (9/48). Spectroscopic follow-up to fainter flux limits is strongly encouraged. Based on observations collected at the European Southern Observatory, Chile, 080.B-0187(A).

Detection of tire tread particles using laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Prochazka, David; Bilík, Martin; Prochazková, Petra; Klus, Jakub; Pořízka, Pavel; Novotný, Jan; Novotný, Karel; Ticová, Barbora; Bradáč, Albert; Semela, Marek; Kaiser, Jozef

2015-06-01

The objective of this paper is a study of the potential of laser induced breakdown spectroscopy (LIBS) for detection of tire tread particles. Tire tread particles may represent pollutants; simultaneously, it is potentially possible to exploit detection of tire tread particles for identification of optically imperceptible braking tracks at locations of road accidents. The paper describes the general composition of tire treads and selection of an element suitable for detection using the LIBS method. Subsequently, the applicable spectral line is selected considering interferences with lines of elements that might be present together with the detected particles, and optimization of measurement parameters such as incident laser energy, gate delay and gate width is performed. In order to eliminate the matrix effect, measurements were performed using 4 types of tires manufactured by 3 different producers. An adhesive tape was used as a sample carrier. The most suitable adhesive tape was selected from 5 commonly available tapes, on the basis of their respective LIBS spectra. Calibration standards, i.e. an adhesive tape with different area content of tire tread particles, were prepared for the selected tire. A calibration line was created on the basis of the aforementioned calibration standards. The linear section of this line was used for determination of the detection limit value applicable to the selected tire. Considering the insignificant influence of matrix of various types of tires, it is possible to make a simple recalculation of the detection limit value on the basis of zinc content in a specific tire.

Analysis of focusing error signals by differential astigmatic method under off-center tracking in the land-groove-type optical disk

NASA Astrophysics Data System (ADS)

Shinoda, Masahisa; Nakatani, Hidehiko

2015-04-01

We theoretically calculate the behavior of the focusing error signal in the land-groove-type optical disk when the objective lens traverses on out of the radius of the optical disk. The differential astigmatic method is employed instead of the conventional astigmatic method for generating the focusing error signals. The signal behaviors are compared and analyzed in terms of the gain difference of the slope sensitivity of the focusing error signals from the land and the groove. In our calculation, the format of digital versatile disc-random access memory (DVD-RAM) is adopted as the land-groove-type optical disk model, and advantageous conditions for suppressing the gain difference are investigated. The calculation method and results described in this paper will be reflected in the next generation land-groove-type optical disks.

Main types of optical beams giving predominant contributions to the light backscatter for the irregular hexagonal columns

NASA Astrophysics Data System (ADS)

Shishko, Victor A.; Konoshonkin, Alexander V.; Kustova, Natalia V.; Borovoi, Anatoli G.

2017-11-01

This work presents the estimation of contribution of the main types of optical beams to the light backscatter for randomly oriented hexagonal ice column, the right dihedral angle of which was distorted within the range of 0° (regular particle) to 10°. Calculations were obtained within the physical optics approximation. The wavelength was 532 nm and the refractive index was 1.3116. The results showed that the total contribution of the main types of optical beams to the total backscattering cross section reach the value of 85% at small distortion angle of the hexagonal column and at substantial distortion angle the total contribution of the main types of optical beams decrease up to 55% of the total backscattering cross section. The obtained conclusions can significantly reduce the calculation time in the case when there is no need for high accuracy of the calculation.

Analysis of tuning methods in semiconductor frequency-selective surfaces

NASA Astrophysics Data System (ADS)

Shemelya, Corey; Palm, Dominic; Fip, Tassilo; Rahm, Marco

2017-02-01

Advanced technology, such as sensing and communication equipment, has recently begun to combine optically sensitive nano-scale structures with customizable semiconductor material systems. Included within this broad field of study is the aptly named frequency-selective surface; which is unique in that it can be artificially designed to produce a specific electromagnetic or optical response. With the inherent utility of a frequency-selective surface, there has been an increased interest in the area of dynamic frequency-selective surfaces, which can be altered through optical or electrical tuning. This area has had exciting break throughs as tuning methods have evolved; however, these methods are typically energy intensive (optical tuning) or have met with limited success (electrical tuning). As such, this work investigates multiple structures and processes which implement semiconductor electrical biasing and/or optical tuning. Within this study are surfaces ranging from transmission meta-structures to metamaterial surface-waves and the associated coupling schemes. This work shows the utility of each design, while highlighting potential methods for optimizing dynamic meta-surfaces. As an added constraint, the structures were also designed to operate in unison with a state-of-the-art Ti:Sapphire Spitfire Ace and Spitfire Ace PA dual system (12 Watt) with pulse front matching THz generation and an EOS detection system. Additionally, the Ti:Sapphire laser system would provide the means for optical tunablity, while electrical tuning can be obtained through external power supplies.

A search for cataclysmic binaries containing strongly magnetic white dwarfs

NASA Technical Reports Server (NTRS)

Bond, H. E.; Chanmugam, G.

1982-01-01

The AM Herculis type binaries which contain accreting white dwarfs with surface magnetic fields of a few times 10 to the seventh power gauss were studied. If white dwarfs in cataclysmic binaries have a range of field strengths similar to that among single white dwarfs. AM Her like systems should exist with fields as high as 3 x 10 to the eighth power gauss. It is suggested that such objects will not have the strong optical polarization of the AM Her variables; however, they exhibit high harmonic cyclotron emission, making them spectacular UV sources. We made IUE observations of seven candidate cataclysmic variables selected for optical similarity to AM Her binaries. Although all seven objects were detected in the UV, none display unusually strong UV continua. It is suggested that the distribution of magnetic field strengths among single white dwarfs may be different from that among binaries.

Multispectral interference filter arrays with compensation of angular dependence or extended spectral range.

PubMed

Frey, Laurent; Masarotto, Lilian; Armand, Marilyn; Charles, Marie-Lyne; Lartigue, Olivier

2015-05-04

Thin film Fabry-Perot filter arrays with high selectivity can be realized with a single patterning step, generating a spatial modulation of the effective refractive index in the optical cavity. In this paper, we investigate the ability of this technology to address two applications in the field of image sensors. First, the spectral tuning may be used to compensate the blue-shift of the filters in oblique incidence, provided the filter array is located in an image plane of an optical system with higher field of view than aperture angle. The technique is analyzed for various types of filters and experimental evidence is shown with copper-dielectric infrared filters. Then, we propose a design of a multispectral filter array with an extended spectral range spanning the visible and near-infrared range, using a single set of materials and realizable on a single substrate.

Chamber catalogues of optical and fluorescent signatures distinguish bioaerosol classes

NASA Astrophysics Data System (ADS)

Hernandez, Mark; Perring, Anne E.; McCabe, Kevin; Kok, Greg; Granger, Gary; Baumgardner, Darrel

2016-07-01

Rapid bioaerosol characterization has immediate applications in the military, environmental and public health sectors. Recent technological advances have facilitated single-particle detection of fluorescent aerosol in near real time; this leverages controlled ultraviolet exposures with single or multiple wavelengths, followed by the characterization of associated fluorescence. This type of ultraviolet induced fluorescence has been used to detect airborne microorganisms and their fragments in laboratory studies, and it has been extended to field studies that implicate bioaerosol to compose a substantial fraction of supermicron atmospheric particles. To enhance the information yield that new-generation fluorescence instruments can provide, we report the compilation of a referential aerobiological catalogue including more than 50 pure cultures of common airborne bacteria, fungi and pollens, recovered at water activity equilibrium in a mesoscale chamber (1 m3). This catalogue juxtaposes intrinsic optical properties and select bandwidths of fluorescence emissions, which manifest to clearly distinguish between major classes of airborne microbes and pollens.

One Thousand New Dwarf Novae from the OGLE Survey

NASA Astrophysics Data System (ADS)

Mróz, P.; Udalski, A.; Poleski, R.; Pietrukowicz, P.; Szymański, M. K.; Soszyński, I.; Wyrzykowski, Ł.; Ulaczyk, K.; Kozłowski, S.; Skowron, J.

2015-12-01

We present one of the largest collections of dwarf novae (DNe) containing 1091 objects that have been discovered in the long-term photometric data from the Optical Gravitational Lensing Experiment (OGLE) survey. They were found in the OGLE fields toward the Galactic bulge and the Magellanic Clouds. We analyze basic photometric properties of all systems and tentatively find a population of DNe from the Galactic bulge. We identify several dozen of WZ Sge-type DN candidates, including two with superhump periods longer than 0.09 d. Other interesting objects include SU UMa-type stars with "early" precursor outbursts or a Z Cam-type star showing outbursts during standstills. We also provide a list of DNe which will be observed during the K2 Campaign 9 microlensing experiment in 2016. Finally, we present the new OGLE-IV real-time data analysis system: CVOM, which has been designed to provide continuous real time photometric monitoring of selected CVs.

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

NASA Technical Reports Server (NTRS)

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

1990-01-01

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

One-step production of phage-silicon nanoparticles by PLAL as fluorescent nanoprobes for cell identification

NASA Astrophysics Data System (ADS)

De Plano, Laura M.; Scibilia, Santi; Rizzo, Maria Giovanna; Crea, Sara; Franco, Domenico; Mezzasalma, Angela M.; Guglielmino, Salvatore P. P.

2018-03-01

Silicon nanoparticles (SiNPs) are widely used as promising nanoplatform owing to their high specific surface area, optical properties and biocompatibility. Silicon nanoparticles find possible application in biomedical environment for their potential quantum effects and the functionalization with biomaterials, too. In this work, we propose a new approach for bio-functionalization of SiNPs and M13-engineered bacteriophage, displaying specific peptides that selectively recognize peripheral blood mononuclear cells (PBMC). The "one-step" functionalization is conducted during the laser ablation of silicon plate in buffer solution with engineered bacteriophages, to obtain SiNPs binding bacteriophages (phage-SiNPs). The interaction between SiNPs and bacteriophage is investigated. Particularly, the optical and morphological characterizations of phage-SiNPs are performed by UV-Vis spectroscopy, scanning electron microscopy operating in transmission mode (STEM) and X-ray spectroscopy (EDX). The functionality of phage-SiNPs is investigated through the photoemissive properties in recognition test on PBMC. Our results showed that phage-SiNPs maintain the capability and the activity to bind PBMC within 30 min. The fluorescence of phage-SiNPs allowed to obtain an optical signal on cell type targets. Finally, the proposed strategy demonstrated its potential use in in vitro applications and could be exploited to realize an optical biosensor to detect a specific target.

Report on the Study of Radiation Damage in Calcium Fluoride and Magnesium Fluoride Crystals for use in Excimer Laser Applications

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

None, None

1999-10-04

A study was performed to investigate the effects of radiation damage in calcium fluoride and magnesium fluoride crystals caused by gamma rays and UV photons from excimer lasers. The purpose was to study and correlate the damage caused by these two different mechanisms in various types of material used for fabricating optical elements in high power excimer lasers and lens systems of lithography tools. These optical systems are easily damaged by the laser itself, and it is necessary to use only the most radiation resistant materials for certain key elements. It was found that a clear correlation exists between the,more » radiation induced damage caused by high energy gamma rays and that produced by UV photons from the excimer laser. This correlation allows a simple procedure to be developed to select the most radiation resistant material at the ingot level, which would be later used to fabricate various components of the optical system. This avoids incurring the additional cost of fabricating actual optical elements with material that would later be damaged under prolonged use. The result of this screening procedure can result in a considerable savings in the overall cost of the lens and laser system.« less

Ultra-precision turning of complex spiral optical delay line

NASA Astrophysics Data System (ADS)

Zhang, Xiaodong; Li, Po; Fang, Fengzhou; Wang, Qichang

2011-11-01

Optical delay line (ODL) implements the vertical or depth scanning of optical coherence tomography, which is the most important factor affecting the scanning resolution and speed. The spinning spiral mirror is found as an excellent optical delay device because of the high-speed and high-repetition-rate. However, it is one difficult task to machine the mirror due to the special shape and precision requirement. In this paper, the spiral mirror with titled parabolic generatrix is proposed, and the ultra-precision turning method is studied for its machining using the spiral mathematic model. Another type of ODL with the segmental shape is also introduced and machined to make rotation balance for the mass equalization when scanning. The efficiency improvement is considered in details, including the rough cutting with the 5- axis milling machine, the machining coordinates unification, and the selection of layer direction in turning. The onmachine measuring method based on stylus gauge is designed to analyze the shape deviation. The air bearing is used as the measuring staff and the laser interferometer sensor as the position sensor, whose repeatability accuracy is proved up to 10nm and the stable feature keeps well. With this method developed, the complex mirror with nanometric finish of 10.7nm in Ra and the form error within 1um are achieved.

Incorporation of wavelength selective devices into waveguides with applications to a miniature spectrometer

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

Stallard, B. R.; Kaushik, S.; Hadley, G. R.

1996-02-01

This report pertains to a Laboratory Directed Research and Development project which was funded for FY94 and FY95. The goal was to develop building blocks for small, cheap sensors that use optical spectroscopy as a means of detecting chemical analytes. Such sensors can have an impact on a wide variety of technologies, such as: industrial process control, environmental monitors, chemical analysis in medicine, and automotive monitors. We describe work in fabricating and demonstrating a waveguide/grating device that can serve as the wavelength dispersive component in a miniature spectrometer. Also, we describe the invention and modeling of a new way tomore » construct an array of optical interference filters using sub-wavelength lithography to tune the index of refraction of a fixed Fabry-Perot cavity. Next we describe progress in more efficiently calculating the fields in grating devices. Finally we present the invention of a new type of near field optical probe, applicable to scanning microscopy or optical data storage, which is based on a circular grating constructed in a waveguide. This result diverges from the original goal of the project but is quite significant in that it promises to increase the data storage capacity of CD-ROMs by 10 times.« less

Optofluidic Modulation of Self-Associated Nanostructural Units Forming Planar Bragg Microcavities.

PubMed

Oliva-Ramirez, Manuel; Barranco, Angel; Löffler, Markus; Yubero, Francisco; González-Elipe, Agustin R

2016-01-26

Bragg microcavities (BMs) formed by the successive stacking of nanocolumnar porous SiO2 and TiO2 layers with slanted, zigzag, chiral, and vertical configurations are prepared by physical vapor deposition at oblique angles while azimuthally varying the substrate orientation during the multilayer growth. The slanted and zigzag BMs act as wavelength-selective optical retarders when they are illuminated with linearly polarized light, while no polarization dependence is observed for the chiral and vertical cavities. This distinct optical behavior is attributed to a self-nanostructuration mechanism involving a fence-bundling association of nanocolumns as observed by focused ion beam scanning electron microscopy in the slanted and zigzag microcavities. The outstanding retarder response of the optically active BMs can be effectively modulated by dynamic infiltration of nano- and mesopores with liquids of different refraction indices acting as a switch of the polarization behavior. The unprecedented polarization and tunable optofluidic properties of these nanostructured photonic systems have been successfully simulated with a simple model that assumes a certain birefringence for the individual stacked layers and accounts for the light interference phenomena developed in the BMs. The possibilities of this type of self-arranged nanostructured and optically active BMs for liquid sensing and monitoring applications are discussed.

Innovative multi-cantilever array sensor system with MOEMS read-out

NASA Astrophysics Data System (ADS)

Ivaldi, F.; Bieniek, T.; Janus, P.; Grabiec, P.; Majstrzyk, W.; Kopiec, D.; Gotszalk, T.

2016-11-01

Cantilever based sensor system are a well-established sensor family exploited in several every-day life applications as well as in high-end research areas. The very high sensitivity of such systems and the possibility to design and functionalize the cantilevers to create purpose built and highly selective sensors have increased the interest of the scientific community and the industry in further exploiting this promising sensors type. Optical deflection detection systems for cantilever sensors provide a reliable, flexible method for reading information from cantilevers with the highest sensitivity. However the need of using multi-cantilever arrays in several fields of application such as medicine, biology or safety related areas, make the optical method less suitable due to its structural complexity. Working in the frame of a the Joint Undertaking project Lab4MEMS II our group proposes a novel and innovative approach to solve this issue, by integrating a Micro-Opto-Electro-Mechanical-System (MOEMS) with dedicated optics, electronics and software with a MOEMS micro-mirror, ultimately developed in the frame of Lab4MEMSII. In this way we are able to present a closely packed, lightweight solution combining the advantages of standard optical read-out systems with the possibility of recording multiple read-outs from large cantilever arrays quasi simultaneously.

Optical properties of metal nanoparticles embedded in amorphous silicon analysed using discrete dipole approximation

NASA Astrophysics Data System (ADS)

Fantoni, Alessandro; Fernandes, Miguel; Vygranenko, Yuri; Vieira, Manuela; Oliveira-Silva, Rui P.; Prazeres, D. M. F.; Ribeiro, Ana P. C.; Alegria, Elisabete C. B. A.

2018-02-01

Localized surface plasmons (LSP) can be excited in metal nanoparticles (NP) by UV, visible or NIR light and are described as coherent oscillation of conduction electrons. Taking advantage of the tunable optical properties of NPs, we propose the realization of a plasmonic structure, based on the LSP interaction of NP with an embedding matrix of amorphous silicon. This study is directed to define the characteristics of NP and substrate necessary to the development of a LSP proteomics sensor that, once provided immobilized antibodies on its surface, will screen the concentration of selected antigens through the determination of LSPR spectra and peaks of light absorption. Metals of interest for NP composition are: Aluminium and Gold. Recent advances in nanoparticle production techniques allow almost full control over shapes and size, permitting full control over their optical and plasmonic properties and, above all, over their responsive spectra. Analytical solution is only possible for simple NP geometries, therefore our analysis, is realized recurring to computer simulation using the Discrete Dipole Approximation method (DDA). In this work we use the free software DDSCAT to study the optical properties of metal nanoparticles embedded in an amorphous silicon matrix, as a function of size, shape, aspect-ratio and metal type. Experimental measurements realized with arrays of metal nanoparticles are compared with the simulations.

Mapping chromatic pathways in the Drosophila visual system.

PubMed

Lin, Tzu-Yang; Luo, Jiangnan; Shinomiya, Kazunori; Ting, Chun-Yuan; Lu, Zhiyuan; Meinertzhagen, Ian A; Lee, Chi-Hon

2016-02-01

In Drosophila, color vision and wavelength-selective behaviors are mediated by the compound eye's narrow-spectrum photoreceptors R7 and R8 and their downstream medulla projection (Tm) neurons Tm5a, Tm5b, Tm5c, and Tm20 in the second optic neuropil or medulla. These chromatic Tm neurons project axons to a deeper optic neuropil, the lobula, which in insects has been implicated in processing and relaying color information to the central brain. The synaptic targets of the chromatic Tm neurons in the lobula are not known, however. Using a modified GFP reconstitution across synaptic partners (GRASP) method to probe connections between the chromatic Tm neurons and 28 known and novel types of lobula neurons, we identify anatomically the visual projection neurons LT11 and LC14 and the lobula intrinsic neurons Li3 and Li4 as synaptic targets of the chromatic Tm neurons. Single-cell GRASP analyses reveal that Li4 receives synaptic contacts from over 90% of all four types of chromatic Tm neurons, whereas LT11 is postsynaptic to the chromatic Tm neurons, with only modest selectivity and at a lower frequency and density. To visualize synaptic contacts at the ultrastructural level, we develop and apply a "two-tag" double-labeling method to label LT11's dendrites and the mitochondria in Tm5c's presynaptic terminals. Serial electron microscopic reconstruction confirms that LT11 receives direct contacts from Tm5c. This method would be generally applicable to map the connections of large complex neurons in Drosophila and other animals. © 2015 Wiley Periodicals, Inc.

The BAT AGN Spectroscopic Survey (BASS)

NASA Astrophysics Data System (ADS)

Koss, Michael; Trakhtenbrot, Benny; Ricci, Claudio; Lamperti, Isabella; Oh, Kyuseok; Berney, Simon; Schawinski, Kevin; Balokovic, Mislav; Baronchelli, Linda; Gehrels, Neil; Stern, Daniel; Mushotzky, Richard; Veilleux, Sylvain; Ueda, Yoshihiro; Crenshaw, D. Michael; Harrison, Fiona; Fischer, Travis C.; Treister, Ezequiel; BASS Team; Swift BAT Team

2017-01-01

We present the Swift BAT AGN Spectroscopic Survey (BASS) and discus the first four papers. The catalog represents an unprecedented census of hard-X-ray selected AGN in the local universe, with ~90% of sources at z<0.2. Starting from an all-sky catalog of AGN detected based on their 14-195 keV flux from the 70-month Swift/BAT catalog, we analyze a total of 1279 optical spectra, taken from twelve dierent telescopes, for a total of 642 spectra of unique AGN. We present the absorption and emission line measurements as well as black hole masses and accretion rates for the majority of obscured and un-obscured AGN (473), representing more than a factor of 10 increase from past studies. Consistent with previous surveys, we find an increase in the fraction of un-obscured (type 1) AGN, as measured from broad Hbeta and Halpha, with increasing 14-195 keV and 2-10 keV luminosity. We find the FWHM of the emission lines to show broad agreement with the X-ray obscuration measurements. Compared to narrow line AGN in the SDSS, the X-ray selected AGN in our sample with emission lines have a larger fraction of dustier galaxies suggesting these types of galaxies are missed in optical AGN surveys using emission line diagnostics. Additionally, we discuss follow-on efforts to study the variation of [OIII] to Xray measurements, a new method to measure accretion rates from using line ratios, a sample of 100 AGN observed with NIR spectroscopy, and an effort to measure the accretion rates and obscuration with merger stage in a subsample of mergers.

Anterior segment morphology and morphometry in selected reptile species using optical coherence tomography.

PubMed

Rival, Franck; Linsart, Adeline; Isard, Pierre-François; Besson, Christian; Dulaurent, Thomas

2015-01-01

To provide new and original images of the anterior segment (AS) of the eye of selected Ophidian, Chelonian, and Saurian species and to compare the AS architecture among and within these three groups. 17 Saurians, 14 Ophidians, and 11 Chelonians with no concurrent systemic or eye disease were included in the study. Age, weight, nose-cloaca distance (NCD), and pupil shape were collected for each animal. The AS was examined by optical coherence tomography (OCT). After gross description of the appearance of the AS, the central and peripheral corneal thickness (CCT, PCT) and anterior chamber depth (ACD) were measured using the software provided with the OCT device. The ratio CCT/ACD was then calculated for each animal. Pupil shape was a vertical slit in all the crepuscular or nocturnal animals (except for 1 chelonian and 1 ophidian). Each group had its own particular AS architecture. Saurians had a regularly thin cornea with a flat anterior lens capsule and a deep anterior chamber. Ophidians had a thick cornea with a narrow anterior chamber due to a very anteriorly anchored spherical lens. The spectacle was difficult to identify in all ophidians except in Python molurus bivitattus in which it was more obvious. Chelonians displayed an intermediate architecture which more closely resembled the Saurian type than the Ophidian type. Despite grossly similar AS architecture, the three groups of reptiles in the study demonstrated differences that are suggestive of a link between anatomical disparities and variations in environment and lifestyle. © 2014 American College of Veterinary Ophthalmologists.

Complications of cataract and refractive surgery: a clinicopathological documentation.

PubMed Central

Apple, D J; Werner, L

2001-01-01

PURPOSE: To present selected complications of keratorefractive and phakic intraocular lens (IOL) surgery and a series of IOLs that required explantation because of various postimplantation opacification of the IOL optic. METHODS: Two specimens obtained after keratorefractive surgery, 2 phakic IOLs, and a total of 23 explanted IOLs from cases in which postimplantation opacification of the IOL optic had occurred were studied. These included 6 Bausch and Lomb (B&L) Hydroview H60 M designs, 9 Medical Developmental Research (MDR) SC60B-OUV designs, and 24 IOLs with rigid PMMA optics that had been implanted in the 1980s and early 1990s. Of the latter, 8 required late explantation because of decreased visual acuity. Analyses performed included gross and light microscopic evaluation, histochemical staining, electron microscopy, and energy-dispersive spectroscopy. RESULTS: We provide examples of 3 postrefractive surgery complications: (1) fungal keratitis after LASIK, (2) post-LASIK corneal decompensation, and (3) cataract formation after implantation of phakic posterior chamber IOLs. Regarding the IOL optic opacities, classifications of 3 types are described: (1) a surface calcification of the B&L Hydroview IOL; (2) diffusion of calcium into the substance of the optic of the hydrophilic "acrylic" SC60B-OUV MDR foldable IOL design, sometimes leading to total opacification of the IOL optic and also its haptics; (3) a distinct pattern of intraoptical opacification with rigid PMMA designs that we term a snowflake degeneration. This term is based on the clinical and pathologic appearance of the individual lesions. Each snowflake lesion represents a focal breakdown of PMMA material as opposed to deposition of exogenous material. CONCLUSIONS: Analysis of complications of refractive surgery represents a new field of ocular pathology. The clinicopathological reports presented here provide an overview of selected complications after refractive surgery. We also help define 3 newly recognized, clinically significant conditions based on postoperative IOL optic opacification. The calcification processes noted on the 2 modern foldable designs studied here (B&L and MDR lenses) need further review by the manufacturers in order to reassess production processes, especially in terms of polymer selection, manufacturing techniques, and other factors required to produce a safe and effective lens. Any lens not meeting today's high standards should not be marketed. The important fact in recognizing the snowflake complication of PMMA IOLs as described here is to alert surgeons about the nature of the lesion so that they will not alarm patients or require extensive and unnecessary testing in trying to determine its pathogenesis. There is no reason why successful explantation cannot be performed in cases where severe visual decrease or loss has occurred. PMID:11797325

Optical properties of β-BBO and potential for THz applications

NASA Astrophysics Data System (ADS)

Nikolaev, N. A.; Andreev, Yu. M.; Antsygin, V. D.; Bekker, T. B.; Ezhov, D. M.; Kokh, A. E.; Kokh, K. A.; Lanskii, G. V.; Mamrashev, A. A.; Svetlichnyi, V. A.

2018-01-01

The anisotropy of optical properties of high quality beta barium borate crystal (β-BaB2O4, β-BBO) was studied in the main transparency window by using classic spectroscopic methods and in the range of 0.2 - 2 THz by using THz time-domain spectroscopy. β-BBO crystals were grown by the top-seeded solution technique in a highly resistive furnace with a heat field of 3-fold axis symmetry. At room temperature (RT), absorption coefficient in the maximal transparency window in grown crystals did not exceed 0.05 cm-1. Strong absorption anisotropy was observed in 3 - 5 μm and the THz range. At 1 THz absorption coefficients for e and o wave were, respectively, 7 cm-1 and 21 cm-1 at RT; 2 cm-1 and 10 cm-1 at 81 K. At the most attractive for out-of-door applications range < 0.4 THz the absorption coefficient is found to be very low: below 0.2 cm-1 at RT and 1 cm-1 at 81 K. Refractive indices dispersions measured by THz-TDS were approximated in the form of Sellmeier equations. Birefringence is found quite large for phase matched difference frequency generation (DFG) or down-conversion into the THz range (THz-DFG) under near IR pump at RT and 81 K. Type II (oe-o and eo-o), and type I (ee-e) three wave interactions can be realized at RT. THz-DFG of Nd:YAG laser and KTP OPO can be realized by type II (oe-o) three-wave interaction. For selected spectral ranges of femtosecond Ti:Sapphire laser efficient phase matched and group velocity matched optical rectification can be realized by another two types of three wave interactions. Accounting other well-known attractive physical properties of β-BBO crystal, wide application in THz technique can be forecasted.

Practical protocols for fast histopathology by Fourier transform infrared spectroscopic imaging

NASA Astrophysics Data System (ADS)

Keith, Frances N.; Reddy, Rohith K.; Bhargava, Rohit

2008-02-01

Fourier transform infrared (FT-IR) spectroscopic imaging is an emerging technique that combines the molecular selectivity of spectroscopy with the spatial specificity of optical microscopy. We demonstrate a new concept in obtaining high fidelity data using commercial array detectors coupled to a microscope and Michelson interferometer. Next, we apply the developed technique to rapidly provide automated histopathologic information for breast cancer. Traditionally, disease diagnoses are based on optical examinations of stained tissue and involve a skilled recognition of morphological patterns of specific cell types (histopathology). Consequently, histopathologic determinations are a time consuming, subjective process with innate intra- and inter-operator variability. Utilizing endogenous molecular contrast inherent in vibrational spectra, specially designed tissue microarrays and pattern recognition of specific biochemical features, we report an integrated algorithm for automated classifications. The developed protocol is objective, statistically significant and, being compatible with current tissue processing procedures, holds potential for routine clinical diagnoses. We first demonstrate that the classification of tissue type (histology) can be accomplished in a manner that is robust and rigorous. Since data quality and classifier performance are linked, we quantify the relationship through our analysis model. Last, we demonstrate the application of the minimum noise fraction (MNF) transform to improve tissue segmentation.

Experimental design to understand the interaction of stellar radiation with molecular clouds

NASA Astrophysics Data System (ADS)

VanDervort, Robert; Davis, Josh; Trantham, Matt; Klein, Sallee; Frank, Yechiel; Raicher, Erez; Fraenkel, Moshe; Shvarts, Dov; Keiter, Paul; Drake, R. Paul

2017-06-01

Enhanced star formation triggered by local O and B type stars is an astrophysical problem of interest. O and B type stars are massive, hot stars that emit an enormous amount of radiation. This radiation acts to either compress or blow apart clumps of gas in the interstellar media. For example, in the optically thick limit, when the x-ray radiation in the gas clump has a short mean free path length the x-ray radiation is absorbed near the clump edge and compresses the clump. In the optically thin limit, when the mean free path is long, the radiation is absorbed throughout acting to heat the clump. This heating explodes the gas clump. Careful selection of parameters, such as foam density or source temperature, allow the experimental platform to access different hydrodynamic regimes. The stellar radiation source is mimicked by a laser irradiated thin gold foil. This will provide a source of thermal x-rays (around ~100 eV). The gas clump is mimicked by a low-density foam around 0.150 g/cc. Simulations were done using radiation hydrodynamics codes to tune the experimental parameters. The experiment will be carried out at the Omega laser facility on OMEGA 60.

Polymeric PLC-type thermo-optic optical attenuator fabricated by UV imprint technique

NASA Astrophysics Data System (ADS)

Kim, Jin Tae; Choi, Choon-Gi

2006-01-01

A planar lightwave circuit-type polymer thermo-optic optical attenuator was fabricated via a UV imprint technique. In order to reduce the step for filling of cores and minimize the detrimental residual slab waveguide, convex ridge-type micro cores for guidance of light were defined with an accuracy of ±0.5 μm on the under-clad by a single step of imprinting. The voltage-controlled polymer optical attenuator showed 30-dB attenuation with 80-mW electrical input power at a wavelength of 1.55 μm. The rise and fall times are less than 5 ms. It displays about 0.2- and 1-dB polarization dependence at 0- and 10-dB attenuations, respectively.

Optical Fiber Sensors Based on Fiber Ring Laser Demodulation Technology

PubMed Central

Xie, Wen-Ge; Wang, Peng-Zhao; Wang, Jian-Zhang

2018-01-01

A review for optical fiber sensors based on fiber ring laser (FRL) demodulation technology is presented. The review focuses on the principles, main structures, and the sensing performances of different kinds of optical fiber sensors based on FRLs. First of all, the theory background of the sensors has been discussed. Secondly, four different types of sensors are described and compared, which includes Mach–Zehnder interferometer (MZI) typed sensors, Fabry–Perot interferometer (FPI) typed sensors, Sagnac typed sensors, and fiber Bragg grating (FBG) typed sensors. Typical studies and main properties of each type of sensors are presented. Thirdly, a comparison of different types of sensors are made. Finally, the existing problems and future research directions are pointed out and analyzed. PMID:29419745

Optical Fiber Sensors Based on Fiber Ring Laser Demodulation Technology.

PubMed

Xie, Wen-Ge; Zhang, Ya-Nan; Wang, Peng-Zhao; Wang, Jian-Zhang

2018-02-08

A review for optical fiber sensors based on fiber ring laser (FRL) demodulation technology is presented. The review focuses on the principles, main structures, and the sensing performances of different kinds of optical fiber sensors based on FRLs. First of all, the theory background of the sensors has been discussed. Secondly, four different types of sensors are described and compared, which includes Mach-Zehnder interferometer (MZI) typed sensors, Fabry-Perot interferometer (FPI) typed sensors, Sagnac typed sensors, and fiber Bragg grating (FBG) typed sensors. Typical studies and main properties of each type of sensors are presented. Thirdly, a comparison of different types of sensors are made. Finally, the existing problems and future research directions are pointed out and analyzed.

Tunable photonic band gaps and optical nonreciprocity by an RF-driving ladder-type system in moving optical lattice

NASA Astrophysics Data System (ADS)

Ba, Nuo; Zhong, Xin; Wang, Lei; Fei, Jin-You; Zhang, Yan; Bao, Qian-Qian; Xiao, Li

2018-03-01

We investigate photonic transport properties of the 1D moving optical lattices filled with vast cold atoms driven into a four-level ladder-type system and obtain dynamically controlled photonic bandgaps and optical nonreciprocity. It is found that the two obvious optical nonreciprocity can be generated at two well-developed photonic bandgaps based on double dark states in the presence of a radio-frequency field. However, when the radio-frequency field is absence, the only one induced photonic bandgaps with distinguishing optical nonreciprocity can be opened up via single dark state. Dynamic control of the induced photonic bandgaps and optical nonreciprocity could be exploited to achieve all-optical diodes and routing for quantum information networks.

Second harmonics HOE recording in Bayfol HX

NASA Astrophysics Data System (ADS)

Bruder, Friedrich-Karl; Fäcke, Thomas; Hagen, Rainer; Hönel, Dennis; Orselli, Enrico; Rewitz, Christian; Rölle, Thomas; Walze, Günther; Wewer, Brita

2015-05-01

Volume Holographic Optical Elements (vHOEs) provide superior optical properties over DOEs (surface gratings) due to high diffraction efficiencies in the -1st order and their excellent Bragg selectivity. Bayer MaterialScience is offering a variety of customized instant-developing photopolymer films to meet requirements for a specific optics design of a phase hologram. For instance, the photopolymer film thickness is an ideal means to adjust the angular and the spectral selectivity while the index modulation can be adopted with the film thickness to achieve a specific required dynamic range. This is especially helpful for transmission type holograms and in multiplex recordings. The selection of different substrates is helpful to achieve the overall optical properties for a targeted application that we support in B2B-focused developments. To provide further guidance on how to record volume holograms in Bayfol HX, we describe in this paper a new route towards the recording of substrate guided vHOEs by using optimized photopolymer films. Furthermore, we discuss special writing conditions that are suitable to create higher 2nd harmonic intensities and their useful applications. Due to total internal reflection (TIR) at the photopolymer-air interface in substrate guided vHOEs, hologram recording with those large diffraction angles cannot usually be done with two free-space beams. Edge-lit recording setups are used to circumvent this limitation. However, such setups require bulky recording blocks or liquid bathes and are complex and hard to align. A different approach that we present in this paper is to exploit 2nd harmonic grating generation in a freespace recording scheme. Those 2nd harmonic components allow the replay of diffraction angles that are normally only accessible with edge-lit writing configurations. Therefore, this approach significantly simplifies master recordings for vHOEs with edge-lit functionalities, which later can be used in contact copy schemes for mass replication. In this paper, we will discuss and illustrate recording parameters to influence 2nd harmonic efficiency in optimized photopolymer films and will explain preferred geometries for recording.

Zero-phonon-line emission of single molecules for applications in quantum information processing

NASA Astrophysics Data System (ADS)

Kiraz, Alper; Ehrl, M.; Mustecaplioglu, O. E.; Hellerer, T.; Brauchle, C.; Zumbusch, A.

2005-07-01

A single photon source which generates transform limited single photons is highly desirable for applications in quantum optics. Transform limited emission guarantees the indistinguishability of the emitted single photons. This, in turn brings groundbreaking applications in linear optics quantum information processing within an experimental reach. Recently, self-assembled InAs quantum dots and trapped atoms have successfully been demonstrated as such sources for highly indistinguishable single photons. Here, we demonstrate that nearly transform limited zero-phonon-line (ZPL) emission from single molecules can be obtained by using vibronic excitation. Furthermore we report the results of coincidence detection experiments at the output of a Michelson-type interferometer. These experiments reveal Hong-Ou-Mandel correlations as a proof of the indistinguishability of the single photons emitted consecutively from a single molecule. Therefore, single molecules constitute an attractive alternative to single InAs quantum dots and trapped atoms for applications in linear optics quantum information processing. Experiments were performed with a home-built confocal microscope keeping the sample in a superfluid liquid Helium bath at 1.4K. We investigated terrylenediimide (TDI) molecules highly diluted in hexadecane (Shpol'skii matrix). A continuous wave single mode dye laser was used for excitation of vibronic transitions of individual molecules. From the integral fluorescence, the ZPL of single molecules was selected with a spectrally narrow interference filter. The ZPL emission was then sent to a scanning Fabry-Perot interferometer for linewidth measurements or a Michelson-type interferometer for coincidence detection.

Nonlinear optical coupler using a doped optical waveguide

DOEpatents

Pantell, Richard H.; Sadowski, Robert W.; Digonnet, Michel J. F.; Shaw, Herbert J.

1994-01-01

An optical mode coupling apparatus includes an Erbium-doped optical waveguide in which an optical signal at a signal wavelength propagates in a first spatial propagation mode and a second spatial propagation mode of the waveguide. The optical signal propagating in the waveguide has a beat length. The coupling apparatus includes a pump source of perturbational light signal at a perturbational wavelength that propagates in the waveguide in the first spatial propagation mode. The perturbational signal has a sufficient intensity distribution in the waveguide that it causes a perturbation of the effective refractive index of the first spatial propagation mode of the waveguide in accordance with the optical Kerr effect. The perturbation of the effective refractive index of the first spatial propagation mode of the optical waveguide causes a change in the differential phase delay in the optical signal propagating in the first and second spatial propagation modes. The change in the differential phase delay is detected as a change in the intensity distribution between two lobes of the optical intensity distribution pattern of an output signal. The perturbational light signal can be selectively enabled and disabled to selectively change the intensity distribution in the two lobes of the optical intensity distribution pattern.

High-power microwave generation using optically activated semiconductor switches

NASA Astrophysics Data System (ADS)

Nunnally, William C.

1990-12-01

The two prominent types of optically controlled switches, the optically controlled linear (OCL) switch and the optically initiated avalanche (OIA) switch, are described, and their operating parameters are characterized. Two transmission line approaches, one using a frozen-wave generator and the other using an injected-wave generator, for generation of multiple cycles of high-power microwave energy using optically controlled switches are discussed. The point design performances of the series-switch, frozen-wave generator and the parallel-switch, injected-wave generator are compared. The operating and performance limitations of the optically controlled switch types are discussed, and additional research needed to advance the development of the optically controlled, bulk, semiconductor switches is indicated.

Drug Modulation of Water–Heme Interactions in Low-Spin P450 Complexes of CYP2C9d and CYP125A1

PubMed Central

Conner, Kip P.; Cruce, Alex A.; Krzyaniak, Matthew D.; Schimpf, Alina M.; Frank, Daniel J.; de Montellano, Paul Ortiz; Atkins, William M.; Bowman, Michael K.

2015-01-01

Azoles and pyridines are commonly incorporated into small molecule inhibitor scaffolds that target cytochromes P450 (CYPs) as a strategy to increase drug binding affinity, impart isoform-dependent selectivity, and improve metabolic stability. Optical absorbance spectra of the CYP–inhibitor complex are widely used to infer whether these inhibitors are ligated directly to the heme iron as catalytically inert, low-spin (type II) complexes. Here, we show that the low-spin complex between a drug-metabolizing CYP2C9 variant and 4-(3-phenyl-propyl)-1H-1,2,3-triazole (PPT) retains an axial water ligand despite exhibiting elements of “classic” type II optical behavior. Hydrogens of the axial water ligand are observed by pulsed electron paramagnetic resonance (EPR) spectroscopy for both inhibitor-free and inhibitor-bound species and show that inhibitor binding does not displace the axial water. A 15N label incorporated into PPT is 0.444 nm from the heme iron, showing that PPT is also in the active site. The reverse type I inhibitor, LP10, of CYP125A1 from Mycobacterium tuberculosis, known from X-ray crystal structures to form a low-spin water-bridged complex, is found by EPR and by visible and near-infrared magnetic circular dichroism spectroscopy to retain the axial water ligand in the complex in solution. PMID:25591012

A polarisation maintaining fiber optimized for high temperature gyroscopes

NASA Astrophysics Data System (ADS)

Tutu, F.; Hill, Mark; Cooper, Laurence; Gillooly, A.

2015-05-01

Fiber optic gyroscopes (FOGs) are being used within increasingly severe environments, requiring operational temperatures in excess of the standard operating range for FOGs. Applications requiring these higher temperatures include: directional drilling of wells in oil and gas fields, space applications and military FOG applications. This paper will describe the relative merits of two high temperature acrylate coatings for an optical fiber designed for a FOG in such operating environments. Results for two high temperature acrylates are presented, tested in a 200m length of loose wound fiber, coiled and supported at 75mm diameter, in line with TIA/EIA-455-192 (FOTP-192). It can be seen that both coating types give very good polarization extinction ratio (PER) performance at high temperature up to 180oC, with better performance shown by one coating type on the low temperature side, since it does not harden to the same extent below 0oC. The long term thermal exposure effects will be discussed and experimental results presented which include testing the PER performance over temperature both before and after an extended period of high temperature endurance. This will demonstrate the relative merits of different styles of coatings. From the PER performance, the h-parameter of the fiber can be calculated and hence the preferred coating type selected and recommended for the customer operating environment.

Integrated optics technology study

NASA Technical Reports Server (NTRS)

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

1982-01-01

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

Optical polarimetry and photometry of X-ray selected BL Lacertae objects

NASA Technical Reports Server (NTRS)

Jannuzi, Buell T.; Smith, Paul S.; Elston, Richard

1993-01-01

We present the data from 3 years of monitoring the optical polarization and apparent brightness of 37 X-ray-selected BL Lacertae objects. The monitored objects include a complete sample drawn from the Einstein Extended Medium Sensitivity Survey. We confirm the BL Lac identifications for 15 of these 22 objects. We include descriptions of the objects and samples in our monitoring program and of the existing complete samples of BL Lac objects, highly polarized quasars, optically violent variable quasars, and blazars.

Thermal management and design for optical refrigeration

NASA Astrophysics Data System (ADS)

Symonds, G.; Farfan, B. G.; Ghasemkhani, M. R.; Albrecht, A. R.; Sheik-Bahae, M.; Epstein, R. I.

2016-03-01

We present our recent work in developing a robust and versatile optical refrigerator. This work focuses on minimizing parasitic energy losses through efficient design and material optimization. The cooler's thermal linkage system and housing are studied using thermal analysis software to minimize thermal gradients through the device. Due to the extreme temperature differences within the device, material selection and characterization are key to constructing an efficient device. We describe the design constraints and material selections necessary for thermally efficient and durable optical refrigeration.

RF and Optical Communications: A Comparison of High Data Rate Returns From Deep Space in the 2020 Timeframe

NASA Technical Reports Server (NTRS)

Williams, W. Dan; Collins, Michael; Boroson, Don M.; Lesh, James; Biswas, Abihijit; Orr, Richard; Schuchman, Leonard; Sands, O. Scott

2007-01-01

As NASA proceeds with plans for increased science data return and higher data transfer capacity for science missions, both RF and optical communications are viable candidates for significantly higher-rate communications from deep space to Earth. With the inherent advantages, smaller apertures and larger bandwidths, of optical communications, it is reasonable to expect that at some point in time and combination of increasing distance and data rate, the rapidly emerging optical capabilities would become more advantageous than the more mature and evolving RF techniques. This paper presents a comparison of the burden to a spacecraft by both RF and optical communications systems for data rates of 10, 100, and 1000 Mbps and large distances. Advanced technology for RF and optical communication systems have been considered for projecting capabilities in the 2020 timeframe. For the comparisons drawn, the optical and RF ground terminals were selected to be similar in cost. The RF system selected is composed of forty-five 12-meter antennas, whereas the selected optical system is equivalent to a 10-meter optical telescope. Potential differences in availability are disregarded since the focus of this study is on spacecraft mass and power burden for high-rate mission data, under the assumption that essential communications will be provided by low-rate, high availability RF. For both the RF and optical systems, the required EIRP, for a given data rate and a given distance, was achieved by a design that realized the lowest possible communications subsystem mass (power + aperture) consistent with achieving the lowest technology risk. A key conclusion of this paper is that optical communications has great potential for high data rates and distances of 2.67 AU and beyond, but requires R&D and flight demonstrations to prove out technologies.

Properties of optically selected BL Lacertae candidates from the SDSS

NASA Astrophysics Data System (ADS)

Kügler, S. D.; Nilsson, K.; Heidt, J.; Esser, J.; Schultz, T.

2014-09-01

Context. Deep optical surveys open the avenue for finding large numbers of BL Lac objects that are hard to identify because they lack the unique properties classifying them as such. While radio or X-ray surveys typically reveal dozens of sources, recent compilations based on optical criteria alone have increased the number of BL Lac candidates considerably. However, these compilations are subject to biases and may contain a substantial number of contaminating sources. Aims: In this paper we extend our analysis of 182 optically selected BL Lac object candidates from the SDSS with respect to an earlier study. The main goal is to determine the number of bona fide BL Lac objects in this sample. Methods: We examine their variability characteristics, determine their broad-band radio-UV spectral energy distributions (SEDs), and search for the presence of a host galaxy. In addition we present new optical spectra for 27 targets with improved signal-to-noise ratio with respect to the SDSS spectra. Results: At least 59% of our targets have shown variability between SDSS DR2 and our observations by more than 0.1-0.27 mag depending on the telescope used. A host galaxy was detected in 36% of our targets. The host galaxy type and luminosities are consistent with earlier studies of BL Lac host galaxies. Simple fits to broad-band SEDs for 104 targets of our sample derived synchrotron peak frequencies between 13.5 ≤ log 10(νpeak) ≤ 16 with a peak at log 10 ~ 14.5. Our new optical spectra do not reveal any new redshift for any of our objects. Thus the sample contains a large number of bona fide BL Lac objects and seems to contain a substantial fraction of intermediate-frequency peaked BL Lacs. Based on observations collected with the NTT on La Silla (Chile) operated by the European Southern Observatory under proposal 082.B-0133.Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA), operated jointly by the Max-Planck-Institut für Astronomie and the Instituto de Astrofisica de Canarias.Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.

Design and simulation of a planar micro-optic free-space receiver

NASA Astrophysics Data System (ADS)

Nadler, Brett R.; Hallas, Justin M.; Karp, Jason H.; Ford, Joseph E.

2017-11-01

We propose a compact directional optical receiver for free-space communications, where a microlens array and micro-optic structures selectively couple light from a narrow incidence angle into a thin slab waveguide and then to an edge-mounted detector. A small lateral translation of the lenslet array controls the coupled input angle, enabling the receiver to select the transmitter source direction. We present the optical design and simulation of a 10mm x 10mm aperture receiver using a 30μm thick silicon waveguide able to couple up to 2.5Gbps modulated input to a 10mm x 30μm wide detector.

A Comparison between Two Heterodyne Light Sources Using Different Electro-Optic Modulators for Optical Temperature Measurements at Visible Wavelengths

PubMed Central

Twu, Ruey-Ching; Lee, Yi-Huan; Hou, Hong-Yao

2010-01-01

In this paper we have successfully demonstrated a z-propagating Zn-indiffused lithium niobate electro-optic modulator used for optical heterodyne interferometry. Compared to a commercial buck-type electro-optic modulator, the proposed waveguide-type modulator has a lower driving voltage and smaller phase variation while measuring visible wavelengths of 532 nm and 632.8 nm. We also demonstrate an optical temperature measurement system using a homemade modulator. The results show that the measurement sensitivities are almost the same values of 25 deg/°C for both the homemade and the buck-type modulators for a sensing light with a wavelength of 632.8 nm. Because photorefractive impacts are essential in the buck-type modulator at a wavelength of 532 nm, it is difficult to obtain reliable phase measurements, whereas the stable phase operation of the homemade one allows the measurement sensitivity to be improved up to 30 deg/°C with the best measurement resolution at about 0.07 °C for 532 nm. PMID:22163429

Observed characteristics of dust storm events over the western United States using meteorological, satellite, and air quality measurements

NASA Astrophysics Data System (ADS)

Lei, H.; Wang, J. X. L.

2014-08-01

To improve dust storm identification over the western United States, historical dust events measured by air quality and satellite observations are analyzed based on their characteristics in data sets of regular meteorology, satellite-based aerosol optical depth (AOD), and air quality measurements. Based on the prevailing weather conditions associated with dust emission, dust storm events are classified into the following four typical types: (1) The key feature of cold front-induced dust storms is their rapid process with strong dust emissions. (2) Events caused by meso- to small-scale weather systems have the highest levels of emissions. (3) Dust storms caused by tropical disturbances show a stronger air concentration of dust and last longer than those in (1) and (2). (4) Dust storms triggered by cyclogenesis last the longest. In this paper, sample events of each type are selected and examined to explore characteristics observed from in situ and remote-sensing measurements. These characteristics include the lasting period, surface wind speeds, areas affected, average loading on ground-based optical and/or air quality measurements, peak loading on ground-based optical and/or air quality measurements, and loading on satellite-based aerosol optical depth. Based on these analyses, we compare the characteristics of the same dust events captured in different data sets in order to define the dust identification criteria. The analyses show that the variability in mass concentrations captured by in situ measurements is consistent with the variability in AOD from stationary and satellite observations. Our analyses also find that different data sets are capable of identifying certain common characteristics, while each data set also provides specific information about a dust storm event. For example, the meteorological data are good at identifying the lasting period and area impacted by a dust event; the ground-based air quality and optical measurements can capture the peak strength well; aerosol optical depth (AOD) from satellite data sets allows us to better identify dust-storm-affected areas and the spatial extent of dust. The current study also indicates that the combination of in situ and satellite observations is a better method to fill gaps in dust storm recordings.

Highly sensitive and selective fluoride detection in water through fluorophore release from a metal-organic framework

PubMed Central

Hinterholzinger, Florian M.; Rühle, Bastian; Wuttke, Stefan; Karaghiosoff, Konstantin; Bein, Thomas

2013-01-01

The detection, differentiation and visualization of compounds such as gases, liquids or ions are key challenges for the design of selective optical chemosensors. Optical chemical sensors employ a transduction mechanism that converts a specific analyte recognition event into an optical signal. Here we report a novel concept for fluoride ion sensing where a porous crystalline framework serves as a host for a fluorescent reporter molecule. The detection is based on the decomposition of the host scaffold which induces the release of the fluorescent dye molecule. Specifically, the hybrid composite of the metal-organic framework NH2-MIL-101(Al) and fluorescein acting as reporter shows an exceptional turn-on fluorescence in aqueous fluoride-containing solutions. Using this novel strategy, the optical detection of fluoride is extremely sensitive and highly selective in the presence of many other anions. PMID:24008779

Electro-optic architecture (EOA) for sensors and actuators in aircraft propulsion systems

NASA Technical Reports Server (NTRS)

Glomb, W. L., Jr.

1989-01-01

Results of a study to design an optimal architecture for electro-optical sensing and control in advanced aircraft and space systems are described. The propulsion full authority digital Electronic Engine Control (EEC) was the focus for the study. The recommended architecture is an on-engine EEC which contains electro-optic interface circuits for fiber-optic sensors on the engine. Size and weight are reduced by multiplexing arrays of functionally similar sensors on a pair of optical fibers to common electro-optical interfaces. The architecture contains common, multiplex interfaces to seven sensor groups: (1) self luminous sensors; (2) high temperatures; (3) low temperatures; (4) speeds and flows; (5) vibration; (6) pressures; and (7) mechanical positions. Nine distinct fiber-optic sensor types were found to provide these sensing functions: (1) continuous wave (CW) intensity modulators; (2) time division multiplexing (TDM) digital optic codeplates; (3) time division multiplexing (TDM) analog self-referenced sensors; (4) wavelength division multiplexing (WDM) digital optic code plates; (5) wavelength division multiplexing (WDM) analog self-referenced intensity modulators; (6) analog optical spectral shifters; (7) self-luminous bodies; (8) coherent optical interferometers; and (9) remote electrical sensors. The report includes the results of a trade study including engine sensor requirements, environment, the basic sensor types, and relevant evaluation criteria. These figures of merit for the candidate interface types were calculated from the data supplied by leading manufacturers of fiber-optic sensors.

Optical and electrical properties of CuMO2 transparent p-type conductors

NASA Astrophysics Data System (ADS)

Draeseke, A. D.; Jayaraj, M. K.; Ulbrich, T.; Kroupp, M.; Tate, J.; Nagarajan, R.; Oblezov, A.; Sleight, A. W.

2001-03-01

Wide band gap oxides of the type CuMO2 with the delafossite structure are p-type conductors and many of them are transparent. Films of these p-type oxides have been grown by sputtering and thermal evaporation, and characterized electrically and optically. We present transport and optical transmission measurements for CuY_1-xCa_xO_2, CuScO_2+x and other similar materials. Conductivities are in the range 1 200 S/cm and depend on details of film preparation. The carriers are p-type as determined by thermopower measurements, and typical Seebeck coefficients are several hundred µV/K. Optical transparency varies considerably, but is about 40% at 550 nm for the highest conductivity films. Excellent transparency can be achieved at the expense of conductivity, and optimization is being studied. Band gaps derived from optical transmission are larger than 3.1 eV. Prototype all-oxide pn diodes have been fabricated. This work was partially supported by the NSF under DMR-0071727 and by the Research Corporation under RA0291.

Studies on microstructure, mechanical and corrosion properties of high nitrogen stainless steel shielded metal arc welds

NASA Astrophysics Data System (ADS)

Mohammed, Raffi; Madhusudhan Reddy, G.; Srinivasa Rao, K.

2018-03-01

The present work is aimed at studying the microstructure, mechanical and corrosion properties of high nitrogen stainless steel shielded metal arc (SMA) welds made with Cromang-N electrode. Basis for selecting this electrode is to increase the solubility of nitrogen in weld metal due to high chromium and manganese content. Microstructures of the welds were characterized using optical microscopy (OM), field emission scanning electron microscopy (FESEM) and electron back scattered diffraction (EBSD) mainly to determine the morphology, phase analysis, grain size and orientation image mapping. Hardness, tensile and ductility bend tests were carried out to determine mechanical properties. Potentio-dynamic polarization testing was carried out to study the pitting corrosion resistance using a GillAC basic electrochemical system. Constant load type testing was carried out to study stress corrosion cracking (SCC) behaviour of welds. The investigation results shown that the selected Cr–Mn–N type electrode resulted in favourable microstructure and completely solidified as single phase coarse austenite. Mechanical properties of SMA welds are found to be inferior when compared to that of base metal and is due to coarse and dendritic structure.

Relationship between optical and X-ray properties of O-type stars surveyed with the Einstein Observatory

NASA Technical Reports Server (NTRS)

Sciortino, S.; Vaiana, G. S.; Harnden, F. R., Jr.; Ramella, M.; Morossi, C.

1990-01-01

An X-ray luminosity function is derived for a representative volume-limited sample of O-type stars selected from the catalog of Galactic O stars surveyed with the Einstein Observatory. It was found that, for the stars of this sample which is ten times larger than any previously analyzed, the level of X-ray emission is strongly correlated with bolometric luminosity, confirming previous findings of an Lx-L(bol) relationship (e.g., Harnden et al., 1979; Pallavicini et al., 1981). Correlations between the Lx and the mass loss rate with the wind terminal velocity or with the rotation rate were weak. However, there was a strong correlation with wind momentum flux as well as with the wind kinetic energy flux.

Chemical sensors for space applications

NASA Technical Reports Server (NTRS)

Bonting, Sjoerd L.

1992-01-01

The payload of the Space Station Freedom will include sensors for frequent monitoring of the water recycling process and for measuring the many biochemical parameters related to onboard experiments. This paper describes the sensor technologies and the types of transducers and selectors considered for these sensors. Particular attention is given to such aspects of monitoring of the water recycling process as the types of water use, the sources of water and their hazards, the sensor systems for monitoring, microbial monitoring, and monitoring toxic metals and organics. An approach for monitoring water recycling is suggested, which includes microbial testing with a potentiometric device (which should be in first line of tests), the use of an ion-selective electrode for inorganic ion determinations, and the use of optic fiber techniques for the determination of total organic carbon.

X-Rays and Infrared Selected AGN

NASA Astrophysics Data System (ADS)

Kirhakos, S. D.; Steiner, J. E.

1990-11-01

RESUMEN. En la busqueda de nucleos activos galacticos (NAG) oscurecidos, seleccionamos una tnuestra de galaxias ernisoras de rayos S infrarrojos, Ia mayoria de las cuales son vistas de perf ii. La 6ptica de la regi6n nuclear de las galaxias seleccionadas revelan que el 76% de ellas muestran lineas de emisi5n La clasificaci6n de los es- pectros de acuerdo a los anchos y a la intensidad de cocientes de lineas muestran que existen 34 NAG, 34 objetos de tipo de transici6n y 34 galaxias de la regi6n con nucleos de tipo regi6n H II. Entre los NAG, 3 son del tipo Seyfert I y las otras son del tipo 2. Sugerimos que los objetos identificados como NAG de llneas angostas son objetos tipo Seyfert I oscurecidos ABSTRACT. Looking for obscured active galactic nuclei (AGN), we selected a sample of infrarediX-rays emitting galaxies, mos"t of which are seen as edge-on. Optical spectroscopy of the nuclear region of the selected galaxies revealed that 76 % of them show emission l 'nes. Classification of the spectra according to the widths and line intensity ratios shows that there are 34 AGN, 34 transition type objects and 43 nuclear HIl-like region galaxies. Among the AGN, three are Seyfert type 1 and the others are type 2 objects. We suggest that the objects identified as narrow line AGN are obscured Seyfert 1. o'L : GALAXIES-ACTIVE - X-RAY S-GENERAL

Optical hydrogen sensors based on metal-hydrides

NASA Astrophysics Data System (ADS)

Slaman, M.; Westerwaal, R.; Schreuders, H.; Dam, B.

2012-06-01

For many hydrogen related applications it is preferred to use optical hydrogen sensors above electrical systems. Optical sensors reduce the risk of ignition by spark formation and are less sensitive to electrical interference. Currently palladium and palladium alloys are used for most hydrogen sensors since they are well known for their hydrogen dissociation and absorption properties at relatively low temperatures. The disadvantages of palladium in sensors are the low optical response upon hydrogen loading, the cross sensitivity for oxygen and carbon, the limited detection range and the formation of micro-cracks after some hydrogen absorption/desorption cycles. In contrast to Pd, we find that the use of magnesium or rear earth bases metal-hydrides in optical hydrogen sensors allow tuning of the detection levels over a broad pressure range, while maintaining a high optical response. We demonstrate a stable detection layer for detecting hydrogen below 10% of the lower explosion limit in an oxygen rich environment. This detection layer is deposited at the bare end of a glass fiber as a micro-mirror and is covered with a thin layer of palladium. The palladium layer promotes the hydrogen uptake at room temperature and acts as a hydrogen selective membrane. To protect the sensor for a long time in air a final layer of a hydrophobic fluorine based coating is applied. Such a sensor can be used for example as safety detector in automotive applications. We find that this type of fiber optic hydrogen sensor is also suitable for hydrogen detection in liquids. As example we demonstrate a sensor for detecting a broad range of concentrations in transformer oil. Such a sensor can signal a warning when sparks inside a high voltage power transformer decompose the transformer oil over a long period.

Selective distillation phenomenon in two-species Bose-Einstein condensates in open boundary optical lattices.

PubMed

Bai, Xiao-Dong; Zhang, Mei; Xiong, Jun; Yang, Guo-Jian; Deng, Fu-Guo

2015-11-24

We investigate the formation of discrete breathers (DBs) and the dynamics of the mixture of two-species Bose-Einstein condensates (BECs) in open boundary optical lattices using the discrete nonlinear Schrödinger equations. The results show that the coupling of intra- and interspecies interaction can lead to the existence of pure single-species DBs and symbiotic DBs (i.e., two-species DBs). Furthermore, we find that there is a selective distillation phenomenon in the dynamics of the mixture of two-species BECs. One can selectively distil one species from the mixture of two-species BECs and can even control dominant species fraction by adjusting the intra- and interspecies interaction in optical lattices. Our selective distillation mechanism may find potential application in quantum information storage and quantum information processing based on multi-species atoms.

Selective distillation phenomenon in two-species Bose-Einstein condensates in open boundary optical lattices

PubMed Central

Bai, Xiao-Dong; Zhang, Mei; Xiong, Jun; Yang, Guo-Jian; Deng, Fu-Guo

2015-01-01

We investigate the formation of discrete breathers (DBs) and the dynamics of the mixture of two-species Bose-Einstein condensates (BECs) in open boundary optical lattices using the discrete nonlinear Schrödinger equations. The results show that the coupling of intra- and interspecies interaction can lead to the existence of pure single-species DBs and symbiotic DBs (i.e., two-species DBs). Furthermore, we find that there is a selective distillation phenomenon in the dynamics of the mixture of two-species BECs. One can selectively distil one species from the mixture of two-species BECs and can even control dominant species fraction by adjusting the intra- and interspecies interaction in optical lattices. Our selective distillation mechanism may find potential application in quantum information storage and quantum information processing based on multi-species atoms. PMID:26597592

Safe Detection System for Hydrogen Leaks

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

Lieberman, Robert A.; Beshay, Manal

2012-02-29

Hydrogen is an "environmentally friendly" fuel for future transportation and other applications, since it produces only pure ("distilled") water when it is consumed. Thus, hydrogen-powered vehicles are beginning to proliferate, with the total number of such vehicles expected to rise to nearly 100,000 within the next few years. However, hydrogen is also an odorless, colorless, highly flammable gas. Because of this, there is an important need for hydrogen safety monitors that can warn of hazardous conditions in vehicles, storage facilities, and hydrogen production plants. To address this need, IOS has developed a unique intrinsically safe optical hydrogen sensing technology, andmore » has embodied it in detector systems specifically developed for safety applications. The challenge of using light to detect a colorless substance was met by creating chemically-sensitized optical materials whose color changes in the presence of hydrogen. This reversible reaction provides a sensitive, reliable, way of detecting hydrogen and measuring its concentration using light from low-cost LEDs. Hydrogen sensors based on this material were developed in three completely different optical formats: point sensors ("optrodes"), integrated optic sensors ("optical chips"), and optical fibers ("distributed sensors") whose entire length responds to hydrogen. After comparing performance, cost, time-to-market, and relative market need for these sensor types, the project focused on designing a compact optrode-based single-point hydrogen safety monitor. The project ended with the fabrication of fifteen prototype units, and the selection of two specific markets: fuel cell enclosure monitoring, and refueling/storage safety. Final testing and development of control software for these markets await future support.« less

A spectroscopic survey of WISE-selected obscured quasars with the southern african large telescope

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

Hainline, Kevin N.; Hickox, Ryan C.; Carroll, Christopher M.

2014-11-10

We present the results of an optical spectroscopic survey of a sample of 40 candidate obscured quasars identified on the basis of their mid-infrared emission detected by the Wide-Field Infrared Survey Explorer (WISE). Optical spectra for this survey were obtained using the Robert Stobie Spectrograph on the Southern African Large Telescope. Our sample was selected with WISE colors characteristic of active galactic nuclei (AGNs), as well as red optical to mid-IR colors indicating that the optical/UV AGN continuum is obscured by dust. We obtain secure redshifts for the majority of the objects that comprise our sample (35/40), and find thatmore » sources that are bright in the WISE W4 (22 μm) band are typically at moderate redshift ((z) = 0.35) while sources fainter in W4 are at higher redshifts ((z) = 0.73). The majority of the sources have narrow emission lines with optical colors and emission line ratios of our WISE-selected sources that are consistent with the locus of AGN on the rest-frame g – z color versus [Ne III] λ3869/[O II] λλ3726+3729 line ratio diagnostic diagram. We also use empirical AGN and galaxy templates to model the spectral energy distributions (SEDs) for the objects in our sample, and find that while there is significant variation in the observed SEDs for these objects, the majority require a strong AGN component. Finally, we use the results from our analysis of the optical spectra and the SEDs to compare our selection criteria to alternate criteria presented in the literature. These results verify the efficacy of selecting luminous obscured AGNs based on their WISE colors.« less

Optically intraconnected computer employing dynamically reconfigurable holographic optical element

NASA Technical Reports Server (NTRS)

Bergman, Larry A. (Inventor)

1992-01-01

An optically intraconnected computer and a reconfigurable holographic optical element employed therein. The basic computer comprises a memory for holding a sequence of instructions to be executed; logic for accessing the instructions in sequence; logic for determining for each the instruction the function to be performed and the effective address thereof; a plurality of individual elements on a common support substrate optimized to perform certain logical sequences employed in executing the instructions; and, element selection logic connected to the logic determining the function to be performed for each the instruction for determining the class of each function and for causing the instruction to be executed by those the elements which perform those associated the logical sequences affecting the instruction execution in an optimum manner. In the optically intraconnected version, the element selection logic is adapted for transmitting and switching signals to the elements optically.

Fabrication and comparison of selective, transparent optics for concentrating solar systems

NASA Astrophysics Data System (ADS)

Taylor, Robert A.; Hewakuruppu, Yasitha; DeJarnette, Drew; Otanicar, Todd P.

2015-09-01

Concentrating optics enable solar thermal energy to be harvested at high temperature (<100oC). As the temperature of the receiver increases, radiative losses can become dominant. In many concentrating systems, the receiver is coated with a selectively absorbing surface (TiNOx, Black Chrome, etc.) to obtain higher efficiency. Commercial absorber coatings are well-developed to be highly absorbing for short (solar) wavelengths, but highly reflective at long (thermal emission) wavelengths. If a solar system requires an analogous transparent, non-absorbing optic - i.e. a cover material which is highly transparent at short wavelengths, but highly reflective at long wavelengths - the technology is simply not available. Low-e glass technology represents a commercially viable option for this sector, but it has only been optimized for visible light transmission. Optically thin metal hole-arrays are another feasible solution, but are often difficult to fabricate. This study investigates combinations of thin film coatings of transparent conductive oxides and nanoparticles as a potential low cost solution for selective solar covers. This paper experimentally compares readily available materials deposited on various substrates and ranks them via an `efficiency factor for selectivity', which represents the efficiency of radiative exchange in a solar collector. Out of the materials studied, indium tin oxide and thin films of ZnS-Ag-ZnS represent the most feasible solutions for concentrated solar systems. Overall, this study provides an engineering design approach and guide for creating scalable, selective, transparent optics which could potentially be imbedded within conventional low-e glass production techniques.

Method and apparatus for chemical and topographical microanalysis

NASA Technical Reports Server (NTRS)

Kossakovski, Dmitri A. (Inventor); Baldeschwieler, John D. (Inventor); Beauchamp, Jesse L. (Inventor)

2002-01-01

A scanning probe microscope is combined with a laser induced breakdown spectrometer to provide spatially resolved chemical analysis of the surface correlated with the surface topography. Topographical analysis is achieved by scanning a sharp probe across the sample at constant distance from the surface. Chemical analysis is achieved by the means of laser induced breakdown spectroscopy by delivering pulsed laser radiation to the sample surface through the same sharp probe, and consequent collection and analysis of emission spectra from plasma generated on the sample by the laser radiation. The method comprises performing microtopographical analysis of the sample with a scanning probe, selecting a scanned topological site on the sample, generating a plasma plume at the selected scanned topological site, and measuring a spectrum of optical emission from the plasma at the selected scanned topological site. The apparatus comprises a scanning probe, a pulsed laser optically coupled to the probe, an optical spectrometer, and a controller coupled to the scanner, laser and spectrometer for controlling the operation of the scanner, laser and spectrometer. The probe and scanner are used for topographical profiling the sample. The probe is also used for laser radiation delivery to the sample for generating a plasma plume from the sample. Optical emission from the plasma plume is collected and delivered to the optical spectrometer so that analysis of emission spectrum by the optical spectrometer allows for identification of chemical composition of the sample at user selected sites.

Synthesis of elastic microfibrillar components fibrillin-1 and fibrillin-2 by human optic nerve head astrocytes in situ and in vitro.

PubMed

Pena, J D; Mello, P A; Hernandez, M R

2000-05-01

The purpose of this study was to identify elastic microfibrillar components fibrillin-1 and fibrillin-2 in optic nerve heads of adult normal and glaucomatous subjects, in cultured optic nerve head astrocytes (type 1B astrocytes), as well as fibrillin-1 in fetal optic nerve heads. To characterize synthesis and gene expression of microfibrillar proteins in human optic nerve heads and cultured type 1B astrocytes, light microscopy immunohistochemistry, in situ hybridization, and RT-PCR or Northern blots were performed. Our results demonstrated that fibrillin-1 was associated with blood vessels, astrocytes in the glial columns and cribriform plates, and with astrocyte processes in the nerve bundles in all samples. In glaucomatous optic nerves there was enhanced fibrillin-1 immunoreactivity, especially surrounding blood vessels. Fibrillin-2 was localized primarily to blood vessels in all samples, without qualitative differences between normal and glaucomatous samples. In fetal optic nerve heads fibrillin-1 mRNA was localized to glial cells and to the blood vessel walls. In adult optic nerve heads, there was little fibrillin-1 mRNA as detectable by in situ hybridization and RT-PCR. There was no detectable upregulation of fibrillin-1 mRNA in glaucoma. In cultured type 1B astrocytes, fibrillin-1 staining was mostly pericellular. There was little fibrillin-2 immunoreactivity. In conclusion, astrocytes from the optic nerve head deposit elastic microfibrillar components in situ and in vitro, with a predominance of fibrillin-1. Upregulation of fibrillin-1 mRNA was not observed in glaucoma, suggesting that increased transcription may occur early in the disease process. Cultures of type 1B astrocytes from the optic nerve head provides a useful model to study mechanisms regulating the interactions of elastin and the microfibrils in optic nerve head astrocytes.

Luminescence Sensors Applied to Water Analysis of Organic Pollutants—An Update

PubMed Central

Ibañez, Gabriela A.; Escandar, Graciela M.

2011-01-01

The development of chemical sensors for environmental analysis based on fluorescence, phosphorescence and chemiluminescence signals continues to be a dynamic topic within the sensor field. This review covers the fundamentals of this type of sensors, and an update on recent works devoted to quantifying organic pollutants in environmental waters, focusing on advances since about 2005. Among the wide variety of these contaminants, special attention has been paid polycyclic aromatic hydrocarbons, pesticides, explosives and emerging organic pollutants. The potential of coupling optical sensors with multivariate calibration methods in order to improve the selectivity is also discussed. PMID:22247654

[Design and optical principles of multifocal lenses].

PubMed

Auffarth, G U; Rabsilber, T M; Kohnen, T; Holzer, M P

2008-06-01

Multifocal intraocular lenses (MIOLs) of different designs have been used for more than 20 years in modern cataract surgery. The first IOLs were either refractive 2-3-zone designs or of diffractive concept. All MIOL types, regardless of manufacturer, show reduced contrast sensitivity and increased glare for years. Nevertheless, even first-generation MIOL patients had very good functional results when patient selection, IOL calculation, and surgical techniques were appropriate. Today's gold standard is foldable, aspherical diffractive, or refractive MIOLS. Advancements in technology allow the possibility that MIOLs will be used for aphakia correction as well as presbyopia correction.

Broccoli/weed/soil discrimination by optical reflectance using neural networks

NASA Astrophysics Data System (ADS)

Hahn, Federico

1995-04-01

Broccoli is grown extensively in Scotland, and has become one of the main vegetables cropped, due to its high yields and profits. Broccoli, weed and soil samples from 6 different farms were collected and their spectra obtained and analyzed using discriminant analysis. High crop/weed/soil discrimination success rates were encountered in each farm, but the selected wavelengths varied in each farm due to differences in broccoli variety, weed species incidence and soil type. In order to use only three wavelengths, neural networks were introduced and high crop/weed/soil discrimination accuracies for each farm were achieved.

Graphene and Carbon Quantum Dot-Based Materials in Photovoltaic Devices: From Synthesis to Applications

PubMed Central

Paulo, Sofia; Palomares, Emilio; Martinez-Ferrero, Eugenia

2016-01-01

Graphene and carbon quantum dots have extraordinary optical and electrical features because of their quantum confinement properties. This makes them attractive materials for applications in photovoltaic devices (PV). Their versatility has led to their being used as light harvesting materials or selective contacts, either for holes or electrons, in silicon quantum dot, polymer or dye-sensitized solar cells. In this review, we summarize the most common uses of both types of semiconducting materials and highlight the significant advances made in recent years due to the influence that synthetic materials have on final performance. PMID:28335285

The optical + infrared L dwarf spectral sequence of young planetary-mass objects in the Upper Scorpius association

NASA Astrophysics Data System (ADS)

Lodieu, N.; Zapatero Osorio, M. R.; Béjar, V. J. S.; Peña Ramírez, K.

2018-01-01

We present the results of photometric and spectroscopic follow-ups of the lowest mass member candidates in the nearest OB association, Upper Scorpius (∼5-10 Myr; 145 ± 17 pc), with the Gran Telescopio de Canarias (GTC) and European Southern Observatory (ESO) Very Large Telescope (VLT). We confirm the membership of the large majority (>80 per cent) of candidates originally selected photometrically and astrometrically based on their spectroscopic features, weak equivalent widths of gravity-sensitive doublets and radial velocities. Confirmed members follow a sequence over a wide magnitude range (J = 17.0-19.3 mag) in several colour-magnitude diagrams with optical, near- and mid-infrared photometry and have near-infrared spectral types in the L1-L7 interval with likely masses below 15 Jupiter masses. We find that optical spectral types tend to be earlier than near-infrared spectral types by a few subclasses for spectral types later than M9. We investigate the behaviour of spectral indices, defined in the literature as a function of spectral type and gravity, by comparison with values reported in the literature for young and old dwarfs. We also derive effective temperatures in the 1900-1600 K range from fits of synthetic model-atmosphere spectra to the observed photometry, but we caution that the procedure carries large uncertainties. We determine bolometric corrections for young L dwarfs with ages of ∼5-10 Myr (Upper Sco association) and find them to be similar in the J band but larger by 0.1-0.4 mag in the K band with respect to field L dwarfs. Finally, we discover two faint young L dwarfs, Visible and Infrared Survey Telescope for Astronomy (VISTA) J1607-2146 (L4.5) and VISTA J1611-2215 (L5), that have Hα emission and possible flux excesses at 4.5 μm, pointing to the presence of accretion from a disc on to the central objects of mass below ∼15MJup at an age of 5-10 Myr.

Highly selective and sensitive optical sensor for determination of Pb2+and Hg2+ ions based on the covalent immobilization of dithizone on agarose membrane

NASA Astrophysics Data System (ADS)

Zargoosh, Kiomars; Babadi, Fatemeh Farhadian

2015-02-01

A highly sensitive and selective optical membrane for determination of Hg2+ and Pb2+ was prepared by covalent immobilization of dithizone on agarose membrane. In addition to its high stability, reproducibility and relatively long lifetime, the proposed optical sensor revealed good selectivity for target ions over a large number of alkali, alkaline earth, transition, and heavy metal ions. The proposed optical membrane displays linear responses from 1.1 × 10-8 to 2.0 × 10-6 mol L-1 and 1.2 × 10-8 to 2.4 × 10-6 mol L-1 for Hg2+ and Pb2+, respectively. The limits of detection (LOD) were 2.0 × 10-9 mol L-1 and 4.0 × 10-9 mol L-1 for Hg2+ and Pb2, respectively. The prepared optical membrane was successfully applied to the determination of Hg2+ and Pb2+ in industrial wastes, spiked tap water and natural waters without any preconcentration step.

Determining the fraction of reddened quasars in COSMOS with multiple selection techniques from X-ray to radio wavelengths

NASA Astrophysics Data System (ADS)

Heintz, K. E.; Fynbo, J. P. U.; Møller, P.; Milvang-Jensen, B.; Zabl, J.; Maddox, N.; Krogager, J.-K.; Geier, S.; Vestergaard, M.; Noterdaeme, P.; Ledoux, C.

2016-10-01

The sub-population of quasars reddened by intrinsic or intervening clouds of dust are known to be underrepresented in optical quasar surveys. By defining a complete parent sample of the brightest and spatially unresolved quasars in the COSMOS field, we quantify to which extent this sub-population is fundamental to our understanding of the true population of quasars. By using the available multiwavelength data of various surveys in the COSMOS field, we built a parent sample of 33 quasars brighter than J = 20 mag, identified by reliable X-ray to radio wavelength selection techniques. Spectroscopic follow-up with the NOT/ALFOSC was carried out for four candidate quasars that had not been targeted previously to obtain a 100% redshift completeness of the sample. The population of high AV quasars (HAQs), a specific sub-population of quasars selected from optical/near-infrared photometry, some of which were shown to be missed in large optical surveys such as SDSS, is found to contribute 21%+9-5 of the parent sample. The full population of bright spatially unresolved quasars represented by our parent sample consists of 39%+9-8 reddened quasars defined by having AV > 0.1, and 21%+9-5 of the sample having E(B-V) > 0.1 assuming the extinction curve of the Small Magellanic Cloud. We show that the HAQ selection works well for selecting reddened quasars, but some are missed because their optical spectra are too blue to pass the g-r color cut in the HAQ selection. This is either due to a low degree of dust reddening or anomalous spectra. We find that the fraction of quasars with contributing light from the host galaxy, causing observed extended spatial morphology, is most dominant at z ≲ 1. At higher redshifts the population of spatially unresolved quasars selected by our parent sample is found to be representative of the full population of bright active galactic nuclei at J< 20 mag. This work quantifies the bias against reddened quasars in studies that are based solely on optical surveys. Partly based on observations made with the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias.

Emerging applications of label-free optical biosensors

NASA Astrophysics Data System (ADS)

Zanchetta, Giuliano; Lanfranco, Roberta; Giavazzi, Fabio; Bellini, Tommaso; Buscaglia, Marco

2017-01-01

Innovative technical solutions to realize optical biosensors with improved performance are continuously proposed. Progress in material fabrication enables developing novel substrates with enhanced optical responses. At the same time, the increased spectrum of available biomolecular tools, ranging from highly specific receptors to engineered bioconjugated polymers, facilitates the preparation of sensing surfaces with controlled functionality. What remains often unclear is to which extent this continuous innovation provides effective breakthroughs for specific applications. In this review, we address this challenging question for the class of label-free optical biosensors, which can provide a direct signal upon molecular binding without using secondary probes. Label-free biosensors have become a consolidated approach for the characterization and screening of molecular interactions in research laboratories. However, in the last decade, several examples of other applications with high potential impact have been proposed. We review the recent advances in label-free optical biosensing technology by focusing on the potential competitive advantage provided in selected emerging applications, grouped on the basis of the target type. In particular, direct and real-time detection allows the development of simpler, compact, and rapid analytical methods for different kinds of targets, from proteins to DNA and viruses. The lack of secondary interactions facilitates the binding of small-molecule targets and minimizes the perturbation in single-molecule detection. Moreover, the intrinsic versatility of label-free sensing makes it an ideal platform to be integrated with biomolecular machinery with innovative functionality, as in case of the molecular tools provided by DNA nanotechnology.

High-Resolution Two-Dimensional Optical Spectroscopy of Electron Spins

NASA Astrophysics Data System (ADS)

Salewski, M.; Poltavtsev, S. V.; Yugova, I. A.; Karczewski, G.; Wiater, M.; Wojtowicz, T.; Yakovlev, D. R.; Akimov, I. A.; Meier, T.; Bayer, M.

2017-07-01

Multidimensional coherent optical spectroscopy is one of the most powerful tools for investigating complex quantum mechanical systems. While it was conceived decades ago in magnetic resonance spectroscopy using microwaves and radio waves, it has recently been extended into the visible and UV spectral range. However, resolving MHz energy splittings with ultrashort laser pulses still remains a challenge. Here, we analyze two-dimensional Fourier spectra for resonant optical excitation of resident electrons to localized trions or donor-bound excitons in semiconductor nanostructures subject to a transverse magnetic field. Particular attention is devoted to Raman coherence spectra, which allow one to accurately evaluate tiny splittings of the electron ground state and to determine the relaxation times in the electron spin ensemble. A stimulated steplike Raman process induced by a sequence of two laser pulses creates a coherent superposition of the ground-state doublet which can be retrieved only optically because of selective excitation of the same subensemble with a third pulse. This provides the unique opportunity to distinguish between different complexes that are closely spaced in energy in an ensemble. The related experimental demonstration is based on photon-echo measurements in an n -type CdTe /(Cd ,Mg )Te quantum-well structure detected by a heterodyne technique. The difference in the sub-μ eV range between the Zeeman splittings of donor-bound electrons and electrons localized at potential fluctuations can be resolved even though the homogeneous linewidth of the optical transitions is larger by 2 orders of magnitude.

The effect of carbon chain length of starting materials on the formation of carbon dots and their optical properties

NASA Astrophysics Data System (ADS)

Pan, Xiaohua; Zhang, Yan; Sun, Xiaobo; Pan, Wei; Yu, Guifeng; Si, Shuxin; Wang, Jinping

2018-04-01

Carbon dots (CDs) have attracted increasing attention due to their high performances and potential applications in wide range of areas. However, their emission mechanism is not clear so far. In order to reveal more factors contributing to the emission of CDs, the effect of carbon chain length of starting materials on the formation of CDs and their optical properties was experimentally investigated in this work. In order to focus on the effect of carbon chain length, the starting materials with C, O, N in fully identical forms and only carbon chain lengths being different were selected for synthesizing CDs, including citric acid (CA) and adipic acid (AA) as carbon sources, and diamines with different carbon chain lengths (H2N(CH2)nNH2, n = 2, 4, 6) as nitrogen sources, as well as ethylenediamine (EDA) as nitrogen source and diacids with different carbon chain lengths (HOOC(CH2)nCOOH, n = 0, 2, 4, 6) as carbon sources. Therefore, the effect of carbon chain length of starting materials on the formation and optical properties of CDs can be systematically investigated by characterizing and comparing the structures and optical properties of as-prepared nine types of CDs. Moreover, the density of –NH2 on the surface of the CDs was quantitatively detected by a spectrophotometry so as to elucidate the relationship between the –NH2 related surface state and the optical properties.

Optic glioma

MedlinePlus

... is a strong association between optic glioma and neurofibromatosis type 1 ( NF1 ). Symptoms The symptoms are due ... brain (intracranial pressure). There may be signs of neurofibromatosis type 1 (NF1). The following tests may be ...

Spitzer Imaging of Planck-Herschel Dusty Proto-Clusters at z=2-3

NASA Astrophysics Data System (ADS)

Cooray, Asantha; Ma, Jingzhe; Greenslade, Joshua; Kubo, Mariko; Nayyeri, Hooshang; Clements, David; Cheng, Tai-An

2018-05-01

We have recently introduced a new proto-cluster selection technique by combing Herschel/SPIRE imaging data and Planck/HFIk all-sky survey point source catalog. These sources are identified as Planck point sources with clumps of Herschel source over-densities with far-IR colors comparable to z=0 ULIRGS redshifted to z=2 to 3. The selection is sensitive to dusty starbursts and obscured QSOs and we have recovered couple of the known proto-clusters and close to 30 new proto-clusters. The candidate proto-clusters selected from this technique have far-IR flux densities several times higher than those that are optically selected, such as using LBG selection, implying that the member galaxies are in a special phase of heightened dusty starburst and dusty QSO activity. This far-IR luminous phase may be short but likely to be necessary piece to understand the whole stellar mass assembly history of clusters. Moreover, our photo-clusters are missed in optical selections, suggesting that optically selected proto-clusters alone do not provide adequate statistics and a comparison of the far-IR and optical selected clusters may reveal the importance of the dusty stellar mass assembly. Here, we propose IRAC observations of six of the highest priority new proto-clusters, to establish the validity of the technique and to determine the total stellar mass through SED models. For a modest observing time the science program will have a substantial impact on an upcoming science topic in cosmology with implications for observations with JWST and WFIRST to understand the mass assembly in the universe.

Tracing the Mass-Dependent Star Formation History of Late-Type Galaxies using X-ray Emission: Results from the CHANDRA Deep Fields

NASA Technical Reports Server (NTRS)

Lehmer, B.D; Brandt, W.N.; Schneider, D.P.; Steffen, A.T.; Alexander, D.M.; Bell, E.F.; Hornschemeier, A.E.; McIntosh, D.H.; Bauer, F.E.; Gilli, R.;

Optical spectroscopy of X-ray sources in the Taurus molecular cloud: discovery of ten new pre-main sequence stars

NASA Astrophysics Data System (ADS)

Scelsi, L.; Sacco, G.; Affer, L.; Argiroffi, C.; Pillitteri, I.; Maggio, A.; Micela, G.

2008-11-01

Aims: We have analyzed optical spectra of 25 X-ray sources identified as potential new members of the Taurus molecular cloud (TMC), in order to confirm their membership in this star-forming region. Methods: Fifty-seven candidate members were previously selected among the X-ray sources in the XEST survey, having a 2MASS counterpart compatible with a pre-main sequence star based on color-magnitude and color-color diagrams. We obtained high-resolution optical spectra for 7 of these candidates with the SARG spectrograph at the TNG telescope, which were used to search for lithium absorption and to measure the Hα line and the radial and rotational velocities. Then, 18 low-resolution optical spectra obtained with the instrument DOLORES for other candidate members were used for spectral classification, for Hα measurements, and to assess membership together with IR color-color and color-magnitude diagrams and additional information from the X-ray data. Results: We found that 3 sources show lithium absorption, with equivalent widths (EWs) of 500 mÅ, broad spectral line profiles, indicating rotational velocities of 20{-}40 km s-1, radial velocities consistent with those for known members, and Hα emission. Two of them are classified as new weak-lined T Tauri stars, while the EW ( -9 Å) of the Hα line and its broad asymmetric profile clearly indicate that the third star (XEST-26-062) is a classical T Tauri star. Fourteen sources observed with DOLORES are M-type stars. Fifteen sources show Hα emission. Six of them have spectra that indicate surface gravity lower than in main sequence stars, and their de-reddened positions in IR color-magnitude diagrams are consistent with their derived spectral type and with pre-main sequence models at the distance of the TMC. The K-type star XEST-11-078 is confirmed as a new member on the basis of the strength of the Hα emission line. Overall, we confirm membership to the TMC for 10 out of 25 X-ray sources observed in the optical. Three sources remain uncertain. Based on data collected with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Centro Galileo Galilei of INAF (Istituto Nazionale di Astrofisica) at the Spanish Observatorio del Roque del los Muchachos of the Instituto de Astrofìsica de Canarias.

Imaging and applied optics: introduction to the feature issue.

PubMed

Zalevsky, Zeev; Arnison, Matthew R; Javidi, Bahram; Testorf, Markus

2018-03-01

This special issue of Applied Optics contains selected papers from OSA's Imaging Congress with particular emphasis on work from mathematics in imaging, computational optical sensing and imaging, imaging systems and applications, and 3D image acquisition and display.

Study on the Optimal Groove Shape and Glue Material for Fiber Bragg Grating Measuring Bolts.

PubMed

Zhao, Yiming; Zhang, Nong; Si, Guangyao; Li, Xuehua

2018-06-02

Fiber Bragg grating (FBG) measuring bolts, as a useful tool to evaluate the behaviors of steel bolts in underground engineering, can be manufactured by gluing the FBG sensors inside the grooves, which are usually symmetrical cuts along the steel bolt rod. The selection of the cut shape and the glue types could perceivably affect the final supporting strength of the bolts. Unfortunately, the impact of cut shape and glue type on bolting strength is not yet clear. In this study, based on direct tension tests, full tensile load⁻displacement curves of rock bolts with different groove shapes were obtained and analyzed. The effects of groove shape on the bolt strength were discussed, and the stress redistribution in the cross-section of a rock bolt with different grooves was simulated using ANSYS. The results indicated that the trapezoidal groove is best for manufacturing the FBG bolt due to its low reduction of supporting strength. Four types of glues commonly used for the FBG sensors were assessed by conducting tensile tests on the mechanical testing and simulation system and the static and dynamic optical interrogators system. Using linear regression analysis, the relationship between the reflected wavelength of FBG sensors and tensile load was obtained. Practical recommendations for glue selection in engineering practice are also provided.

All-optical OXC transition strategy from WDM optical network to elastic optical network.

PubMed

Chen, Xin; Li, Juhao; Guo, Bingli; Zhu, Paikun; Tang, Ruizhi; Chen, Zhangyuan; He, Yongqi

2016-02-22

Elastic optical network (EON) has been proposed recently as a spectrum-efficient optical layer to adapt to rapidly-increasing traffic demands instead of current deployed wavelength-division-multiplexing (WDM) optical network. In contrast with conventional WDM optical cross-connect (OXCs) based on wavelength selective switches (WSSs), the EON OXCs are based on spectrum selective switches (SSSs) which are much more expensive than WSSs, especially for large-scale switching architectures. So the transition cost from WDM OXCs to EON OXCs is a major obstacle to realizing EON. In this paper, we propose and experimentally demonstrate a transition OXC (TOXC) structure based on 2-stage cascading switching architectures, which make full use of available WSSs in current deployed WDM OXCs to reduce number and port count of required SSSs. Moreover, we propose a contention-aware spectrum allocation (CASA) scheme for EON built with the proposed TOXCs. We show by simulation that the TOXCs reduce the network capital expenditure transiting from WDM optical network to EON about 50%, with a minor traffic blocking performance degradation and about 10% accommodated traffic number detriment compared with all-SSS EON OXC architectures.

Photobiology of Symbiodinium revisited: bio-physical and bio-optical signatures

NASA Astrophysics Data System (ADS)

Hennige, S. J.; Suggett, D. J.; Warner, M. E.; McDougall, K. E.; Smith, D. J.

2009-03-01

Light is often the most abundant resource within the nutrient-poor waters surrounding coral reefs. Consequently, zooxanthellae ( Symbiodinium spp.) must continually photoacclimate to optimise productivity and ensure coral success. In situ coral photobiology is becoming dominated by routine assessments using state-of-the-art non-invasive bio-optical or chlorophyll a fluorescence (bio-physical) techniques. Multiple genetic types of Symbiodinium are now known to exist; however, little focus has been given as to how these types differ in terms of characteristics that are observable using these techniques. Therefore, this investigation aimed to revisit and expand upon a pivotal study by Iglesias-Prieto and Trench (1994) by comparing the photoacclimation characteristics of different Symbiodinium types based on their bio-physical (chlorophyll a fluorescence, reaction centre counts) and bio-optical (optical absorption, pigment concentrations) ‘signatures’. Signatures described here are unique to Symbiodinium type and describe phenotypic responses to set conditions, and hence are not suitable to describe taxonomic structure of in hospite Symbiodinium communities. In this study, eight Symbiodinium types from clades and sub-clades (A-B, F) were grown under two PFDs (Photon Flux Density) and examined. The photoacclimation response by Symbiodinium was highly variable between algal types for all bio-physical and for many bio-optical measurements; however, a general preference to modifying reaction centre content over effective antennae-absorption was observed. Certain bio-optically derived patterns, such as light absorption, were independent of algal type and, when considered per photosystem, were matched by reaction centre stoichiometry. Only by better understanding genotypic and phenotypic variability between Symbiodinium types can future studies account for the relative taxonomic and physiological contribution by Symbiodinium to coral acclimation.

Spectroscopic and electrochemical characterization of some Schiff base metal complexes containing benzoin moiety

NASA Astrophysics Data System (ADS)

El-Shahawi, M. S.; Al-Jahdali, M. S.; Bashammakh, A. S.; Al-Sibaai, A. A.; Nassef, H. M.

2013-09-01

The ligation behavior of bis-benzoin ethylenediamine (B2ED) and benzoin thiosemicarbazone (BTS) Schiff bases towards Ru3+, Rh3+, Pd2+, Ni2+ and Cu2+ were determined. The bond length of M-N and spectrochemical parameters (10Dq, β, B and LFSE) of the complexes were evaluated. The redox characteristics of selected complexes were explored by cyclic voltammetry (CV) at Pt working electrode in non aqueous solvents. Au mesh (100 w/in.) optically transparent thin layer electrode (OTTLE) was also used for recording thin layer CV for selected Ru complex. Oxidation of some complexes occurs in a consecutive chemical reaction of an EC type mechanism. The characteristics of electron transfer process of the couples M2+/M3+ and M3+/M4+ (M = Ru3+, Rh3+) and the stability of the complexes towards oxidation and/or reduction were assigned. The nature of the electroactive species and reduction mechanism of selected electrode couples were assigned.

Radio variability in complete samples of extragalactic radio sources at 1.4 GHz

NASA Astrophysics Data System (ADS)

Rys, S.; Machalski, J.

1990-09-01

Complete samples of extragalactic radio sources obtained in 1970-1975 and the sky survey of Condon and Broderick (1983) were used to select sources variable at 1.4 GHz, and to investigate the characteristics of variability in the whole population of sources at this frequency. The radio structures, radio spectral types, and optical identifications of the selected variables are discussed. Only compact flat-spectrum sources vary at 1.4 GHz, and all but four are identified with QSOs, BL Lacs, or other (unconfirmed spectroscopically) stellar objects. No correlation of degree of variability at 1.4 GHz with Galactic latitude or variability at 408 MHz has been found, suggesting that most of the 1.4-GHz variability is intrinsic and not caused by refractive scintillations. Numerical models of the variability have been computed.

Optical sensing of hydrogen sulphate using rhodamine 6G hydrazide from aqueous medium

NASA Astrophysics Data System (ADS)

Upadhyay, Yachana; Bothra, Shilpa; Kumar, Rajender; Choi, Heung-Jin; Sahoo, Suban K.

2017-06-01

This communication reports the application of rhodamine 6G hydrazide (L) for the selective colorimetric and turn-on fluorescent sensing of hydrogen sulphate ions from aqueous medium. The ring opening of the colourless spirocyclic form of L was selectively triggered in the presence of HSO4- among the other tested anions (F-, Cl-, Br-, I-, AcO-, H2PO4-, NO3-, ClO4-, CN-, HO-, AsO33 - and SO42 -), which gives rise to a pink colour and strong fluorescence in the visible region. Sensor L showed a detection limit down to micromolar range without any interference from the other tested competitive anions. Sensor L was applied for the construction of two inputs (HO- and HSO4-) INHIBIT type molecular logic gate and naked-eye detection of HSO4- using test paper strips.

Method of developing all-optical trinary JK, D-type, and T-type flip-flops using semiconductor optical amplifiers.

PubMed

Garai, Sisir Kumar

2012-04-10

To meet the demand of very fast and agile optical networks, the optical processors in a network system should have a very fast execution rate, large information handling, and large information storage capacities. Multivalued logic operations and multistate optical flip-flops are the basic building blocks for such fast running optical computing and data processing systems. In the past two decades, many methods of implementing all-optical flip-flops have been proposed. Most of these suffer from speed limitations because of the low switching response of active devices. The frequency encoding technique has been used because of its many advantages. It can preserve its identity throughout data communication irrespective of loss of light energy due to reflection, refraction, attenuation, etc. The action of polarization-rotation-based very fast switching of semiconductor optical amplifiers increases processing speed. At the same time, tristate optical flip-flops increase information handling capacity.

Optical ridge waveguides preserving the thermo-optic features in LiNbO3 crystals fabricated by combination of proton implantation and selective wet etching.

PubMed

Tan, Yang; Chen, Feng

2010-05-24

We report on a new, simple method to fabricate optical ridge waveguides in a z-cut LiNbO3 wafer by using proton implantation and selective wet etching. The measured modal field is well confined in the ridge waveguide region, which is also confirmed by the numerical simulation. With thermal annealing treatment at 400 degrees C, the propagation loss of the ridge waveguides is determined to be as low as approximately 0.9 dB/cm. In addition, the measured thermo-optic coefficients of the waveguides are in good agreement with those of the bulk, suggesting potential applications in integrated photonics.

VizieR Online Data Catalog: NIR spectral analysis of star-forming galaxies (Genzel+, 2014)

NASA Astrophysics Data System (ADS)

Genzel, R.; Forster Schreiber, N. M.; Rosario, D.; Lang, P.; Lutz, D.; Wisnioski, E.; Wuyts, E.; Wuyts, S.; Bandara, K.; Bender, R.; Berta, S.; Kurk, J.; Mendel, J. T.; Tacconi, L. J.; Wilman, D.; Beifiori, A.; Brammer, G.; Burkert, A.; Buschkamp, P.; Chan, J.; Carollo, C. M.; Davies, R.; Eisenhauer, F.; Fabricius, M.; Fossati, M.; Kriek, M.; Kulkarni, S.; Lilly, S. J.; Mancini, C.; Momcheva, I.; Naab, T.; Nelson, E. J.; Renzini, A.; Saglia, R.; Sharples, R. M.; Sternberg, A.; Tacchella, S.; van Dokkum, P.

2017-02-01

For the analysis in this paper, we included a total of 110 SFGs at z~1-3 with near-IR integral field or slit spectroscopy covering the Hα+[NII] line emission from surveys carried out with SINFONI, KMOS, LUCI, and GNIRS. The targets for these surveys were originally drawn from rest-frame optical, UV, and near-IR selected samples in broadband imaging surveys with optical spectroscopic redshifts, and from stellar mass-selected samples with near-IR or optical spectroscopic redshifts. (2 data files).

Selective detection of Escherichia coli by imaging of the light intensity transmitted through an optical disk

NASA Astrophysics Data System (ADS)

Shiramizu, Hideyuki; Kuroda, Chiaki; Ohki, Yoshimichi; Shima, Takayuki; Wang, Xiaomin; Fujimaki, Makoto

2018-03-01

We have developed an optical disk system for imaging transmitted light from Escherichia coli dispersed on an optical disk. When E. coli was stained using Bismarck brown, the transmittance was found to decrease in images obtained at λ = 405 nm. The results indicate that transmittance imaging is suitable for finding the difference in light intensity between stained and unstained E. coli, whereas the reflectance images were scarcely changed by staining. Therefore, E. coli can be selectively discriminated from abiotic contaminants using transmittance imaging.

U-Shaped and Surface Functionalized Polymer Optical Fiber Probe for Glucose Detection.

PubMed

Azkune, Mikel; Ruiz-Rubio, Leire; Aldabaldetreku, Gotzon; Arrospide, Eneko; Pérez-Álvarez, Leyre; Bikandi, Iñaki; Zubia, Joseba; Vilas-Vilela, Jose Luis

2017-12-25

In this work we show an optical fiber evanescent wave absorption probe for glucose detection in different physiological media. High selectivity is achieved by functionalizing the surface of an only-core poly(methyl methacrylate) (PMMA) polymer optical fiber with phenilboronic groups, and enhanced sensitivity by using a U-shaped geometry. Employing a supercontinuum light source and a high-resolution spectrometer, absorption measurements are performed in the broadband visible light spectrum. Experimental results suggest the feasibility of such a fiber probe as a low-cost and selective glucose detector.

Power selective optical filter devices and optical systems using same

DOEpatents

Koplow, Jeffrey P

2014-10-07

In an embodiment, a power selective optical filter device includes an input polarizer for selectively transmitting an input signal. The device includes a wave-plate structure positioned to receive the input signal, which includes at least one substantially zero-order, zero-wave plate. The zero-order, zero-wave plate is configured to alter a polarization state of the input signal passing in a manner that depends on the power of the input signal. The zero-order, zero-wave plate includes an entry and exit wave plate each having a fast axis, with the fast axes oriented substantially perpendicular to each other. Each entry wave plate is oriented relative to a transmission axis of the input polarizer at a respective angle. An output polarizer is positioned to receive a signal output from the wave-plate structure and selectively transmits the signal based on the polarization state.

Wavelength-versatile optical vortex lasers

NASA Astrophysics Data System (ADS)

Omatsu, Takashige; Miyamoto, Katsuhiko; Lee, Andrew J.

2017-12-01

The unique properties of optical vortex beams, in particular their spiral wavefront, have resulted in the emergence of a wide range of unique applications for this type of laser output. These applications include optical tweezing, free space optical communications, microfabrication, environmental optics, and astrophysics. However, much like the laser in its infancy, the adaptation of this type of laser output requires a diversity of wavelengths. We report on recent progress on development of optical vortex laser sources and in particular, focus on their wavelength extension, where nonlinear optical processes have been used to generate vortex laser beams with wavelengths which span the ultraviolet to infrared. We show that nonlinear optical conversion can be used to not only diversify the output wavelength of these sources, but can be used to uniquely engineer the wavefront and spatial properties of the laser output.

Microstructured optical fiber-based luminescent biosensing: Is there any light at the end of the tunnel? - A review.

PubMed

Pidenko, Sergey A; Burmistrova, Natalia A; Shuvalov, Andrey A; Chibrova, Anastasiya A; Skibina, Yulia S; Goryacheva, Irina Y

2018-08-17

This review covers the current state of the art of luminescent biosensors based on various types of microstructured optical fiber. The unique optical and structural properties of this type of optical fiber make them one of the most promising integrated platforms for bioassays. The individual sections of this review are devoted to a) classification of microstructured optical fibers, b) microstructured optical fiber materials, c) aspects of biosensing based on the biomolecules incorporated into the microstructured optical fibers, and d) development of models for prediction of the efficiency of luminescent signal processing. The authors' views on current trends and limitations of microstructured optical fibers for biosensing as well as the most promising areas and technologies for application in analytical practice are presented. Copyright © 2017 Elsevier B.V. All rights reserved.

Efficient 'Optical Furnace': A Cheaper Way to Make Solar Cells is Reaching the Marketplace

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

von Kuegelgen, T.

In Bhushan Sopori's laboratory, you'll find a series of optical furnaces he has developed for fabricating solar cells. When not in use, they sit there discreetly among the lab equipment. But when a solar silicon wafer is placed inside one for processing, Sopori walks over to a computer and types in a temperature profile. Almost immediately this fires up the furnace, which glows inside and selectively heats up the silicon wafer to 800 degrees centigrade by the intense light it produces. Sopori, a principal engineer at the National Renewable Energy Laboratory, has been researching and developing optical furnace technology formore » around 20 years. He says it's a challenging technology to develop because there are many issues to consider when you process a solar cell, especially in optics. Despite the challenges, Sopori and his research team have advanced the technology to the point where it will benefit all solar cell manufacturers. They are now developing a commercial version of the furnace in partnership with a manufacturer. 'This advanced optical furnace is highly energy efficient, and it can be used to manufacture any type of solar cell,' he says. Each type of solar cell or manufacturing process typically requires a different furnace configuration and temperature profile. With NREL's new optical furnace system, a solar cell manufacturer can ask the computer for any temperature profile needed for processing a solar cell, and the same type of furnace is suitable for several solar cell fabrication process steps. 'In the future, solar cell manufacturers will only need this one optical furnace because it can be used for any process, including diffusion, metallization and oxidation,' Sopori says. 'This helps reduce manufacturing costs.' One startup company, Applied Optical Systems, has recognized the furnace's potential for manufacturing thin-film silicon cells. 'We'd like to develop thin-film silicon cells with higher efficiencies, up to 15 to 18 percent, and we believe this furnace will enable us to do so,' says A. Rangappan, founder and CEO of Applied Optical Systems. Rangappan also says it will take only a few minutes for the optical furnace to process a thin-film solar cell, which reduces manufacturing costs. Overall, he estimates the company's solar cell will cost around 80 cents per watt. For manufacturing these thin-film silicon cells, Applied Optical Systems and NREL have developed a partnership through a cooperative research and development agreement (CRADA) to construct an optical furnace system prototype. DOE is providing $500,000 from its Technology Commercialization Development Fund to help offset the prototype's development costs because of the technology's significant market potential. The program has provided the NREL technology transfer office with a total of $4 million to expand such collaborative efforts between NREL researchers and companies. Applied Optical will construct a small version of the optical furnace based on the prototype design in NREL's process development and integration laboratory through a separate CRADA. This small furnace will only develop one solar cell wafer at a time. Then, the company will construct a large, commercial-scale optical furnace at its own facilities, which will turn out around 1,000 solar cell wafers per hour. 'We hope to start using the optical furnace for manufacturing within four to five years,' Rangappan says. Meanwhile, another partnership using the optical furnace has evolved between NREL and SiXtron Advanced Materials, another startup. Together they'll use the optical furnace to optimize the metallization process for novel antireflective solar cell coatings. The process is not only expected to yield higher efficiencies for silicon-based solar cells, but also lowers processing costs and eliminates safety concerns for manufacturers. Most solar cell manufacturers currently use a plasma-enhanced chemical vapor deposition (PECVD) system with compressed and extremely pyrophoric silane gas (SiH4) for applying passivation antireflective coatings (ARC). If silane is exposed to air, the SiH4 will explode - a serious safety issue for high-volume manufacturers. SiXtron's process uses a solid, silicon-based polymer that's converted into noncompressed, nonexplosive gas, which then flows to a standard PECVD system. 'The solid source is so safe to handle that it can be shipped by FedEx,' says Zbigniew Barwicz, president and CEO of SiXtron. Barwicz says manufacturers can use the same PECVD processing equipment for the SiXtron process that they already use for SiH4, a plug-and-play solution. For this novel passivation ARC process, NREL is helping to optimize the metallization parameters. NREL has developed a new technology called optical processing. One of the applications of this process is fire-through contact formation of silicon solar cells.« less

Mini-Survey Of SDSS of [OIII] AGN With Swift

NASA Technical Reports Server (NTRS)

Angelini, L.; George, I. M.; Hill, J.; Padgett, C. A.; Mushotzky, R. F.

2008-01-01

The number of AGN and their luminosity distribution are crucial parameters for our understanding of the AGN phenomenon. Recent work (e.g. Ferrarese and Merritt 2000) strongly suggests every massive galaxy has a central black hole. However, most of these objects either are not radiating or have been very difficult to detect. We are now in the era of large surveys, and the luminosity function (LF) of AGN has been estimated in various ways. In the X-ray band, Chandra and XMM surveys (e.g., Barger et al. 2005; Hasinger, et al. 2005) have revealed that the LF of Hard X-ray selected AGN shows a strong luminosity-dependent evolution with a dramatic break towards low L(x) (at al z). This is seen for all types of AGN, but is stronger for the broad-line objects (e.g., Steffen et al. 2004). In sharp contrast, the local LF of optically-selected samples shows no such break and no differences between narrow and broad-line objects (Hao et al. 2005). If, as been suggested, hard X-ray and optical emission line can both be fair indicators of AGN activity, it is important to first understand how reliable these characteristics are if we hope to understand the apparent discrepancy in the LFs.

Developing an Approach to Model UV Fluxes in Smoke Laden Conditions over Central Asia

NASA Astrophysics Data System (ADS)

Park, Y. H.; Sokolik, I. N.

2016-12-01

The UV characteristics of smoke aerosols are valuable inputs to the UV Index forecasts, air quality studies, and assessments of the impact of regional environmental changes. The wavelength dependence of light absorption by aerosol particles is pronounced throughout the UV spectral region. Also in assumption that smoke consists of BC, OC, and Sulfate, the mass fraction of smoke is different with fire types. The purpose of this study is to introduce an approach to calculate the UV fluxes in the aerosol laden conditions, and investigate the irradiance compared to measured irradiance in the UV spectrum. To compute the spectral optical properties (e.g., the effective single scattering albedo, asymmetry parameter, and aerosol optical thickness) for the selected scenarios, the representative size distribution and the refractive index are selected and used in the Mie code. Smoke aerosol information (e.g. emission injection height, mass concentration of smoke components) from WRF Chem is applied to run tropospheric ultraviolet and visible (TUV) model. Using the TUV model, we make the comparisons between model and measured irradiance in UV spectrum in smoke aerosol conditions. An advantage of this approach and the uncertainty of the evaluation are discussed. Overall, the results of this investigation show that this approach is valuable to estimate UV fluxes in smoke laden conditions.

Hunting for brown dwarf binaries with X-Shooter

NASA Astrophysics Data System (ADS)

Manjavacas, E.; Goldman, B.; Alcalá, J. M.; Zapatero-Osorio, M. R.; Béjar, B. J. S.; Homeier, D.; Bonnefoy, M.; Smart, R. L.; Henning, T.; Allard, F.

2015-05-01

The refinement of the brown dwarf binary fraction may contribute to the understanding of the substellar formation mechanisms. Peculiar brown dwarf spectra or discrepancy between optical and near-infrared spectral type classification of brown dwarfs may indicate unresolved brown dwarf binary systems. We obtained medium-resolution spectra of 22 brown dwarfs of potential binary candidates using X-Shooter at the VLT. We aimed to select brown dwarf binary candidates. We also tested whether BT-Settl 2014 atmospheric models reproduce the physics in the atmospheres of these objects. To find different spectral type spectral binaries, we used spectral indices and we compared the selected candidates to single spectra and composition of two single spectra from libraries, to try to reproduce our X-Shooter spectra. We also created artificial binaries within the same spectral class, and we tried to find them using the same method as for brown dwarf binaries with different spectral types. We compared our spectra to the BT-Settl models 2014. We selected six possible candidates to be combination of L plus T brown dwarfs. All candidates, except one, are better reproduced by a combination of two single brown dwarf spectra than by a single spectrum. The one-sided F-test discarded this object as a binary candidate. We found that we are not able to find the artificial binaries with components of the same spectral type using the same method used for L plus T brown dwarfs. Best matches to models gave a range of effective temperatures between 950 K and 1900 K, a range of gravities between 4.0 and 5.5. Some best matches corresponded to supersolar metallicity.

Bionanomaterials and Bioinspired Nanostructures for Selective Vapor Sensing

NASA Astrophysics Data System (ADS)

Potyrailo, Radislav; Naik, Rajesh R.

2013-07-01

At present, monitoring of air at the workplace, in urban environments, and on battlefields; exhaled air from medical patients; air in packaged food containers; and so forth can be accomplished with different types of analytical instruments. Vapor sensors have their niche in these measurements when an unobtrusive, low-power, and cost-sensitive technical solution is required. Unfortunately, existing vapor sensors often degrade their vapor-quantitation accuracy in the presence of high levels of interferences and cannot quantitate several components in complex gas mixtures. Thus, new sensing approaches with improved sensor selectivity are required. This technological task can be accomplished by the careful design of sensing materials with new performance properties and by coupling these materials with the suitable physical transducers. This review is focused on the assessment of the capabilities of bionanomaterials and bioinspired nanostructures for selective vapor sensing. We demonstrate that these sensing materials can operate with diverse transducers based on electrical, mechanical, and optical readout principles and can provide vapor-response selectivity previously unattainable by using other sensing materials. This ability for selective vapor sensing provides opportunities to significantly impact the major directions in development and application scenarios of vapor sensors.

Impairments Computation for Routing Purposes in a Transparent-Access Optical Network Based on Optical CDMA and WDM

NASA Astrophysics Data System (ADS)

Musa, Ahmed

2016-06-01

Optical access networks are becoming more widespread and the use of multiple services might require a transparent optical network (TON). Multiplexing and privacy could benefit from the combination of wavelength division multiplexing (WDM) and optical coding (OC) and wavelength conversion in optical switches. The routing process needs to be cognizant of different resource types and characteristics such as fiber types, fiber linear impairments such as attenuation, dispersion, etc. as well as fiber nonlinear impairments such as four-wave mixing, cross-phase modulation, etc. Other types of impairments, generated by optical nodes or photonic switches, also affect the signal quality (Q) or the optical signal to noise ratio (OSNR), which is related to the bit error rate (BER). Therefore, both link and switch impairments must be addressed and somehow incorporated into the routing algorithm. However, it is not practical to fully integrate all photonic-specific attributes in the routing process. In this study, new routing parameters and constraints are defined that reflect the distinct characteristics of photonic networking. These constraints are applied to the design phase of TON and expressed as a cost or metric form that will be used in the network routing algorithm.

Subcarrier multiplexing with dispersion reduction and direct detection

DOEpatents

Sargis, Paul D.; Haigh, Ronald E.; McCammon, Kent G.

1997-01-01

An SCM system for simultaneously reducing the concomitant problems of receiver complexity and dispersion penalty and without requiring the use of an expensive, high-bandwidth optical detector. The system provides both a dispersion reduction and a direct detection to the receiver, with microwave mixers and lithium niobate external modulators that produce sidebands that are only separated by a few gigahertz from a principal laser optical carrier. Digital data streams are independently impressed upon these sidebands for transmission over an ordinary single-mode fiber. Independent high-speed data streams are upconverted to microwave frequencies. These subcarriers are then combined with a microwave power combiner and amplified with a microwave amplifier. A solid-state 1550-nm laser carrier is modulated by the microwave subcarriers. An erbium-doped fiber amplifier (EDFA) is used just prior to long-distance transmission over ordinary single-mode fiber. The transmitted optical signal may then traverse multiple EDFAs to compensate for long-haul optical fiber losses prior to detection. At a receiving end, the optical signal is split into multiple paths. The subcarrier channels are optically pre-selected using a narrowband optical filter, such as a fiber Fabry-Perot (FFP) filter. An optical detector converts the selected optical signal into a baseband electrical data stream.

Host Galaxy Properties of the Swift BAT Ultra Hard X-Ray Selected AGN

NASA Technical Reports Server (NTRS)

Koss, Michael; Mushotzky, Richard; Veilleux, Sylvain; Winter, Lisa M.; Baumgartner, Wayne; Tueller, Jack; Gehrels, Neil; Valencic, Lynne

2011-01-01

We have assembled the largest sample of ultra hard X-ray selected (14-195 keV) AGN with host galaxy optical data to date, with 185 nearby (z<0.05), moderate luminosity AGN from the Swift Burst Alert Telescope (BAT) sample. The BAT AGN host galaxies have intermediate optical colors (u -- r and g -- r) that are bluer than a comparison sample of inactive galaxies and optically selected AGN from the Sloan Digital Sky Survey (SDSS) which are chosen to have the same stellar mass. Based on morphological classifications from the RC3 and the Galaxy Zoo, the bluer colors of BAT AGN are mainly due to a higher fraction of mergers and massive spirals than in the comparison samples. BAT AGN in massive galaxies (log Stellar Mass >10.5) have a 5 to 10 times higher rate of spiral morphologies than in SDSS AGN or inactive galaxies. We also see enhanced far-IR emission in BAT AGN suggestive of higher levels of star formation compared to the comparison samples. BAT AGN are preferentially found in the most massive host galaxies with high concentration indexes indicative of large bulge-to-disk ratios and large supermassive black holes. The narrow-line (NL) BAT AGN have similar intrinsic luminosities as the SDSS NL Seyferts based on measurements of [O III] Lambda 5007. There is also a correlation between the stellar mass and X-ray emission. The BAT AGN in mergers have bluer colors and greater ultra hard X-ray emission compared to the BAT sample as whole. In agreement with the Unified Model of AGN, and the relatively unbiased nature of the BAT sources, the host galaxy colors and morphologies are independent of measures of obscuration such as X-ray column density or Seyfert type. The high fraction of massive spiral galaxies and galaxy mergers in BAT AGN suggest that host galaxy morphology is related to the activation and fueling of local AGN.

Probing large-scale structure with large samples of X-ray selected AGN. I. Baryonic acoustic oscillations

NASA Astrophysics Data System (ADS)

Hütsi, Gert; Gilfanov, Marat; Kolodzig, Alexander; Sunyaev, Rashid

2014-12-01

We investigate the potential of large X-ray-selected AGN samples for detecting baryonic acoustic oscillations (BAO). Though AGN selection in X-ray band is very clean and efficient, it does not provide redshift information, and thus needs to be complemented with an optical follow-up. The main focus of this study is (i) to find the requirements needed for the quality of the optical follow-up and (ii) to formulate the optimal strategy of the X-ray survey, in order to detect the BAO. We demonstrate that redshift accuracy of σ0 = 10-2 at z = 1 and the catastrophic failure rate of ffail ≲ 30% are sufficient for a reliable detection of BAO in future X-ray surveys. Spectroscopic quality redshifts (σ0 = 10-3 and ffail ~ 0) will boost the confidence level of the BAO detection by a factor of ~2. For meaningful detection of BAO, X-ray surveys of moderate depth of Flim ~ few 10-15 erg s-1/cm2 covering sky area from a few hundred to ~ten thousand square degrees are required. The optimal strategy for the BAO detection does not necessarily require full sky coverage. For example, in a 1000 day-long survey by an eROSITA type telescope, an optimal strategy would be to survey a sky area of ~9000 deg2, yielding a ~16σ BAO detection. A similar detection will be achieved by ATHENA+ or WFXT class telescopes in a survey with a duration of 100 days, covering a similar sky area. XMM-Newton can achieve a marginal BAO detection in a 100-day survey covering ~400 deg2. These surveys would demand a moderate-to-high cost in terms the optical follow-ups, requiring determination of redshifts of ~105 (XMM-Newton) to ~3 × 106 objects (eROSITA, ATHENA+, and WFXT) in these sky areas.

The Complete Local Volume Groups Sample - I. Sample selection and X-ray properties of the high-richness subsample

NASA Astrophysics Data System (ADS)

O'Sullivan, Ewan; Ponman, Trevor J.; Kolokythas, Konstantinos; Raychaudhury, Somak; Babul, Arif; Vrtilek, Jan M.; David, Laurence P.; Giacintucci, Simona; Gitti, Myriam; Haines, Chris P.

2017-12-01

We present the Complete Local-Volume Groups Sample (CLoGS), a statistically complete optically selected sample of 53 groups within 80 Mpc. Our goal is to combine X-ray, radio and optical data to investigate the relationship between member galaxies, their active nuclei and the hot intra-group medium (IGM). We describe sample selection, define a 26-group high-richness subsample of groups containing at least four optically bright (log LB ≥ 10.2 LB⊙) galaxies, and report the results of XMM-Newton and Chandra observations of these systems. We find that 14 of the 26 groups are X-ray bright, possessing a group-scale IGM extending at least 65 kpc and with luminosity >1041 erg s-1, while a further three groups host smaller galaxy-scale gas haloes. The X-ray bright groups have masses in the range M500 ≃ 0.5-5 × 1013 M⊙, based on system temperatures of 0.4-1.4 keV, and X-ray luminosities in the range 2-200 × 1041 erg s-1. We find that ∼53-65 per cent of the X-ray bright groups have cool cores, a somewhat lower fraction than found by previous archival surveys. Approximately 30 per cent of the X-ray bright groups show evidence of recent dynamical interactions (mergers or sloshing), and ∼35 per cent of their dominant early-type galaxies host active galactic nuclei with radio jets. We find no groups with unusually high central entropies, as predicted by some simulations, and confirm that CLoGS is in principle capable of detecting such systems. We identify three previously unrecognized groups, and find that they are either faint (LX, R500 < 1042 erg s-1) with no concentrated cool core, or highly disturbed. This leads us to suggest that ∼20 per cent of X-ray bright groups in the local universe may still be unidentified.

HOST GALAXY PROPERTIES OF THE SWIFT BAT ULTRA HARD X-RAY SELECTED ACTIVE GALACTIC NUCLEUS

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

Koss, Michael; Mushotzky, Richard; Veilleux, Sylvain

We have assembled the largest sample of ultra hard X-ray selected (14-195 keV) active galactic nucleus (AGN) with host galaxy optical data to date, with 185 nearby (z < 0.05), moderate luminosity AGNs from the Swift BAT sample. The BAT AGN host galaxies have intermediate optical colors (u - r and g - r) that are bluer than a comparison sample of inactive galaxies and optically selected AGNs from the Sloan Digital Sky Survey (SDSS) which are chosen to have the same stellar mass. Based on morphological classifications from the RC3 and the Galaxy Zoo, the bluer colors of BATmore » AGNs are mainly due to a higher fraction of mergers and massive spirals than in the comparison samples. BAT AGNs in massive galaxies (log M{sub *} >10.5) have a 5-10 times higher rate of spiral morphologies than in SDSS AGNs or inactive galaxies. We also see enhanced far-infrared emission in BAT AGN suggestive of higher levels of star formation compared to the comparison samples. BAT AGNs are preferentially found in the most massive host galaxies with high concentration indexes indicative of large bulge-to-disk ratios and large supermassive black holes. The narrow-line (NL) BAT AGNs have similar intrinsic luminosities as the SDSS NL Seyferts based on measurements of [O III] {lambda}5007. There is also a correlation between the stellar mass and X-ray emission. The BAT AGNs in mergers have bluer colors and greater ultra hard X-ray emission compared to the BAT sample as a whole. In agreement with the unified model of AGNs, and the relatively unbiased nature of the BAT sources, the host galaxy colors and morphologies are independent of measures of obscuration such as X-ray column density or Seyfert type. The high fraction of massive spiral galaxies and galaxy mergers in BAT AGNs suggest that host galaxy morphology is related to the activation and fueling of local AGN.« less

Rainbow Plasmonic Nanobubbles: Synergistic Activation of Gold Nanoparticle Clusters

PubMed Central

Lukianova-Hleb, Ekaterina Y; Oginsky, Alexander O; Shenefelt, Derek L; Drezek, Rebekah A; Hafner, Jason H; Farach-Carson, Mary C; Lapotko, Dmitri O

2011-01-01

The synergistic physical and biological effects of selective targeting and activation of plasmonic nanoparticles were studied for a transient vapor nanobubble mode. Simultaneous optical activation of two plasmon resonances in multi-nanoparticle clusters significantly improved the selectivity and efficacy of the nanobubble generation through and was termed “rainbow plasmonic nanobubbles.” The rainbow nanobubble mechanism has been studied in water and in living cells in vitro. This mechanism provided maximal selectivity of the nanobubble generation in both models and therefore, can the therapeutic selectivity and optical contrast of gold nanoparticles in a heterogeneous physiological microenvironment at cell level. PMID:21804947

Diode-laser-based RIMS measurements of strontium-90

NASA Astrophysics Data System (ADS)

Bushaw, B. A.; Cannon, B. D.

1998-12-01

Double- and triple-resonance excitation schemes for the ionization of strontium are presented. Use of single-mode diode lasers for the resonance excitations provides a high degree of optical isotopic selectivity: with double-resonance, selectivity of >104 for 90Sr against the stable Sr isotopes has been demonstrated. Measurement of lineshapes and stable isotope shifts in the triple-resonance process indicate that optical selectivity should increase to ˜109. When combined with mass spectrometer selectivity this is sufficient for measurement of 90Sr at background environmental levels. Additionally, autoionizing resonances have been investigated for improving ionization efficiency with lower power lasers.

Foucault imaging by using non-dedicated transmission electron microscope

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

Taniguchi, Yoshifumi; Matsumoto, Hiroaki; Harada, Ken

2012-08-27

An electron optical system for observing Foucault images was constructed using a conventional transmission electron microscope without any special equipment for Lorentz microscopy. The objective lens was switched off and an electron beam was converged by a condenser optical system to the crossover on the selected area aperture plane. The selected area aperture was used as an objective aperture to select the deflected beam for Foucault mode, and the successive image-forming lenses were controlled for observation of the specimen images. The irradiation area on the specimen was controlled by selecting the appropriate diameter of the condenser aperture.

Partially reduced graphene oxide based FRET on fiber-optic interferometer for biochemical detection

NASA Astrophysics Data System (ADS)

Yao, B. C.; Wu, Y.; Yu, C. B.; He, J. R.; Rao, Y. J.; Gong, Y.; Fu, F.; Chen, Y. F.; Li, Y. R.

2016-03-01

Fluorescent resonance energy transfer (FRET) with naturally exceptional selectivity is a powerful technique and widely used in chemical and biomedical analysis. However, it is still challenging for conventional FRET to perform as a high sensitivity compact sensor. Here we propose a novel ‘FRET on Fiber’ concept, in which a partially reduced graphene oxide (prGO) film is deposited on a fiber-optic modal interferometer, acting as both the fluorescent quencher for the FRET and the sensitive cladding for optical phase measurement due to refractive index changes in biochemical detection. The target analytes induced fluorescence recovery with good selectivity and optical phase shift with high sensitivity are measured simultaneously. The functionalized prGO film coated on the fiber-optic interferometer shows high sensitivities for the detections of metal ion, dopamine and single-stranded DNA (ssDNA), with detection limits of 1.2 nM, 1.3 μM and 1 pM, respectively. Such a prGO based ‘FRET on fiber’ configuration, bridging the FRET and the fiber-optic sensing technology, may serve as a platform for the realization of series of integrated ‘FRET on Fiber’ sensors for on-line environmental, chemical, and biomedical detection, with excellent compactness, high sensitivity, good selectivity and fast response

Partially reduced graphene oxide based FRET on fiber-optic interferometer for biochemical detection

PubMed Central

Yao, B. C.; Wu, Y.; Yu, C. B.; He, J. R.; Rao, Y. J.; Gong, Y.; Fu, F.; Chen, Y. F.; Li, Y. R.

2016-01-01

Fluorescent resonance energy transfer (FRET) with naturally exceptional selectivity is a powerful technique and widely used in chemical and biomedical analysis. However, it is still challenging for conventional FRET to perform as a high sensitivity compact sensor. Here we propose a novel ‘FRET on Fiber’ concept, in which a partially reduced graphene oxide (prGO) film is deposited on a fiber-optic modal interferometer, acting as both the fluorescent quencher for the FRET and the sensitive cladding for optical phase measurement due to refractive index changes in biochemical detection. The target analytes induced fluorescence recovery with good selectivity and optical phase shift with high sensitivity are measured simultaneously. The functionalized prGO film coated on the fiber-optic interferometer shows high sensitivities for the detections of metal ion, dopamine and single-stranded DNA (ssDNA), with detection limits of 1.2 nM, 1.3 μM and 1 pM, respectively. Such a prGO based ‘FRET on fiber’ configuration, bridging the FRET and the fiber-optic sensing technology, may serve as a platform for the realization of series of integrated ‘FRET on Fiber’ sensors for on-line environmental, chemical, and biomedical detection, with excellent compactness, high sensitivity, good selectivity and fast response PMID:27010752

Investigation of UV photocurable microcapsule inner crosslink extent

NASA Astrophysics Data System (ADS)

Li, Xiaowei; Meng, Shuangshuang; Lai, Weidong; Yu, Haiyang; Fu, Guangsheng

2008-11-01

UV photocuring technology has encountered increased applications in recent years, which finds a variety of applications on protective coating of the optical-fiber, ink and optical recording materials. Combined with techniques of photohardenable, microcapsule, heat-sensitive and interface-polymerization method, a novel photoheat sensitive recording material of non-silver salt is explored in this thesis. Microcapsules are particulate substance with a core and shell structure, where photopolymerizable composition, monofunctional/polyfunctional diluents, photopolymerization initiator, photosensitivity enhancing agent and dye precursor are encapsulated as the internal phase. In this paper introduced the characteristics and curing mechanism of photo-sensitive microcapsule materials. The photocuring process may be a complex-function with photopolymerizable compound and photopolymerization initiator. For the sake of high photocuring speed and degree, optimal photo-sensitive materials were selected. In order to match with the light source excitation wavelength and absorb more wider ultraviolet band, combined type of photo-polymerization initiators were employed. With the kinds and dosage of photopolymerization initiator changing, the photocuring speed and quality can be ameliorated. Through studying the UV-visible absorption spectrum and infra-red spectrum of the material , the optical response property of the inner compound can be obtained.

Detection and Delineation of Oral Cancer With a PARP1-Targeted Optical Imaging Agent.

PubMed

Kossatz, Susanne; Weber, Wolfgang; Reiner, Thomas

2017-01-01

More sensitive and specific methods for early detection are imperative to improve survival rates in oral cancer. However, oral cancer detection is still largely based on visual examination and histopathology of biopsy material, offering no molecular selectivity or spatial resolution. Intuitively, the addition of optical contrast could improve oral cancer detection and delineation, but so far no molecularly targeted approach has been translated. Our fluorescently labeled small-molecule inhibitor PARPi-FL binds to the DNA repair enzyme poly(ADP-ribose)polymerase 1 (PARP1) and is a potential diagnostic aid for oral cancer delineation. Based on our preclinical work, a clinical phase I/II trial opened in March 2017 to evaluate PARPi-FL as a contrast agent for oral cancer imaging. In this commentary, we discuss why we chose PARP1 as a biomarker for tumor detection and which particular characteristics make PARPi-FL an excellent candidate to image PARP1 in optically guided applications. We also comment on the potential benefits of our molecularly targeted PARPi-FL-guided imaging approach in comparison to existing oral cancer screening adjuncts and mention the adaptability of PARPi-FL imaging to other environments and tumor types.

Interference graph-based dynamic frequency reuse in optical attocell networks

NASA Astrophysics Data System (ADS)

Liu, Huanlin; Xia, Peijie; Chen, Yong; Wu, Lan

2017-11-01

Indoor optical attocell network may achieve higher capacity than radio frequency (RF) or Infrared (IR)-based wireless systems. It is proposed as a special type of visible light communication (VLC) system using Light Emitting Diodes (LEDs). However, the system spectral efficiency may be severely degraded owing to the inter-cell interference (ICI), particularly for dense deployment scenarios. To address these issues, we construct the spectral interference graph for indoor optical attocell network, and propose the Dynamic Frequency Reuse (DFR) and Weighted Dynamic Frequency Reuse (W-DFR) algorithms to decrease ICI and improve the spectral efficiency performance. The interference graph makes LEDs can transmit data without interference and select the minimum sub-bands needed for frequency reuse. Then, DFR algorithm reuses the system frequency equally across service-providing cells to mitigate spectrum interference. While W-DFR algorithm can reuse the system frequency by using the bandwidth weight (BW), which is defined based on the number of service users. Numerical results show that both of the proposed schemes can effectively improve the average spectral efficiency (ASE) of the system. Additionally, improvement of the user data rate is also obtained by analyzing its cumulative distribution function (CDF).

Variability-selected active galactic nuclei from supernova search in the Chandra deep field south

NASA Astrophysics Data System (ADS)

Trevese, D.; Boutsia, K.; Vagnetti, F.; Cappellaro, E.; Puccetti, S.

2008-09-01

Context: Variability is a property shared by virtually all active galactic nuclei (AGNs), and was adopted as a criterion for their selection using data from multi epoch surveys. Low Luminosity AGNs (LLAGNs) are contaminated by the light of their host galaxies, and cannot therefore be detected by the usual colour techniques. For this reason, their evolution in cosmic time is poorly known. Consistency with the evolution derived from X-ray detected samples has not been clearly established so far, also because the low luminosity population consists of a mixture of different object types. LLAGNs can be detected by the nuclear optical variability of extended objects. Aims: Several variability surveys have been, or are being, conducted for the detection of supernovae (SNe). We propose to re-analyse these SNe data using a variability criterion optimised for AGN detection, to select a new AGN sample and study its properties. Methods: We analysed images acquired with the wide field imager at the 2.2 m ESO/MPI telescope, in the framework of the STRESS supernova survey. We selected the AXAF field centred on the Chandra Deep Field South where, besides the deep X-ray survey, various optical data exist, originating in the EIS and COMBO-17 photometric surveys and the spectroscopic database of GOODS. Results: We obtained a catalogue of 132 variable AGN candidates. Several of the candidates are X-ray sources. We compare our results with an HST variability study of X-ray and IR detected AGNs, finding consistent results. The relatively high fraction of confirmed AGNs in our sample (60%) allowed us to extract a list of reliable AGN candidates for spectroscopic follow-up observations. Table [see full text] is only available in electronic form at http://www.aanda.org

Integrated optics technology study

NASA Technical Reports Server (NTRS)

Chen, B.

1982-01-01

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

Genetics Home Reference: optic atrophy type 1

MedlinePlus

... Sources for This Page Delettre-Cribaillet C, Hamel CP, Lenaers G. Optic Atrophy Type 1. 2007 Jul ... Zanlonghi X, Charlin JF, Kaplan J, Odent S, Hamel CP, Procaccio V, Reynier P, Amati-Bonneau P. Molecular ...

Star formation in the local Universe from the CALIFA sample. I. Calibrating the SFR using integral field spectroscopy data

NASA Astrophysics Data System (ADS)

Catalán-Torrecilla, C.; Gil de Paz, A.; Castillo-Morales, A.; Iglesias-Páramo, J.; Sánchez, S. F.; Kennicutt, R. C.; Pérez-González, P. G.; Marino, R. A.; Walcher, C. J.; Husemann, B.; García-Benito, R.; Mast, D.; González Delgado, R. M.; Muñoz-Mateos, J. C.; Bland-Hawthorn, J.; Bomans, D. J.; Del Olmo, A.; Galbany, L.; Gomes, J. M.; Kehrig, C.; López-Sánchez, Á. R.; Mendoza, M. A.; Monreal-Ibero, A.; Pérez-Torres, M.; Sánchez-Blázquez, P.; Vilchez, J. M.; Califa Collaboration

2015-12-01

Context. The star formation rate (SFR) is one of the main parameters used to analyze the evolution of galaxies through time. The need for recovering the light reprocessed by dust commonly requires the use of low spatial resolution far-infrared data. Recombination line luminosities provide an alternative, although uncertain dust-extinction corrections based on narrowband imaging or long-slit spectroscopy have traditionally posed a limit to their applicability. Integral field spectroscopy (IFS) is clearly the way to overcome this kind of limitation. Aims: We obtain integrated Hα, ultraviolet (UV) and infrared (IR)-based SFR measurements for 272 galaxies from the CALIFA survey at 0.005

Characterizing the Optical Variability of Bright Blazars: Variability-based Selection of Fermi Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

Ruan, John J.; Anderson, Scott F.; MacLeod, Chelsea L.; Becker, Andrew C.; Burnett, T. H.; Davenport, James R. A.; Ivezić, Željko; Kochanek, Christopher S.; Plotkin, Richard M.; Sesar, Branimir; Stuart, J. Scott

2012-11-01

We investigate the use of optical photometric variability to select and identify blazars in large-scale time-domain surveys, in part to aid in the identification of blazar counterparts to the ~30% of γ-ray sources in the Fermi 2FGL catalog still lacking reliable associations. Using data from the optical LINEAR asteroid survey, we characterize the optical variability of blazars by fitting a damped random walk model to individual light curves with two main model parameters, the characteristic timescales of variability τ, and driving amplitudes on short timescales \\hat{\\sigma }. Imposing cuts on minimum τ and \\hat{\\sigma } allows for blazar selection with high efficiency E and completeness C. To test the efficacy of this approach, we apply this method to optically variable LINEAR objects that fall within the several-arcminute error ellipses of γ-ray sources in the Fermi 2FGL catalog. Despite the extreme stellar contamination at the shallow depth of the LINEAR survey, we are able to recover previously associated optical counterparts to Fermi active galactic nuclei with E >= 88% and C = 88% in Fermi 95% confidence error ellipses having semimajor axis r < 8'. We find that the suggested radio counterpart to Fermi source 2FGL J1649.6+5238 has optical variability consistent with other γ-ray blazars and is likely to be the γ-ray source. Our results suggest that the variability of the non-thermal jet emission in blazars is stochastic in nature, with unique variability properties due to the effects of relativistic beaming. After correcting for beaming, we estimate that the characteristic timescale of blazar variability is ~3 years in the rest frame of the jet, in contrast with the ~320 day disk flux timescale observed in quasars. The variability-based selection method presented will be useful for blazar identification in time-domain optical surveys and is also a probe of jet physics.

Applications of Optical Scanners in an Academic Center.

ERIC Educational Resources Information Center

Molinari, Carol; Tannenbaum, Robert S.

1995-01-01

Describes optical scanners, including how the technology works; applications in data management and research; development of instructional materials; and providing community services. Discussion includes the three basic types of optical scanners: optical character recognition (OCR), optical mark readers (OMR), and graphic scanners. A sidebar…

Simulation-based investigation of the generality of Lyzenga's multispectral bathymetry formula in Case-1 coral reef water

NASA Astrophysics Data System (ADS)

Manessa, Masita Dwi Mandini; Kanno, Ariyo; Sagawa, Tatsuyuki; Sekine, Masahiko; Nurdin, Nurjannah

2018-01-01

Lyzenga's multispectral bathymetry formula has attracted considerable interest due to its simplicity. However, there has been little discussion of the effect that variation in optical conditions and bottom types-which commonly appears in coral reef environments-has on this formula's results. The present paper evaluates Lyzenga's multispectral bathymetry formula for a variety of optical conditions and bottom types. A noiseless dataset of above-water remote sensing reflectance from WorldView-2 images over Case-1 shallow coral reef water is simulated using a radiative transfer model. The simulation-based assessment shows that Lyzenga's formula performs robustly, with adequate generality and good accuracy, under a range of conditions. As expected, the influence of bottom type on depth estimation accuracy is far greater than the influence of other optical parameters, i.e., chlorophyll-a concentration and solar zenith angle. Further, based on the simulation dataset, Lyzenga's formula estimates depth when the bottom type is unknown almost as accurately as when the bottom type is known. This study provides a better understanding of Lyzenga's multispectral bathymetry formula under various optical conditions and bottom types.

THE CLUSTERING OF ALFALFA GALAXIES: DEPENDENCE ON H I MASS, RELATIONSHIP WITH OPTICAL SAMPLES, AND CLUES OF HOST HALO PROPERTIES

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

Papastergis, Emmanouil; Giovanelli, Riccardo; Haynes, Martha P.

We use a sample of ≈6000 galaxies detected by the Arecibo Legacy Fast ALFA (ALFALFA) 21 cm survey to measure the clustering properties of H I-selected galaxies. We find no convincing evidence for a dependence of clustering on galactic atomic hydrogen (H I) mass, over the range M{sub H{sub I}} ≈ 10{sup 8.5}-10{sup 10.5} M{sub ☉}. We show that previously reported results of weaker clustering for low H I mass galaxies are probably due to finite-volume effects. In addition, we compare the clustering of ALFALFA galaxies with optically selected samples drawn from the Sloan Digital Sky Survey (SDSS). We findmore » that H I-selected galaxies cluster more weakly than even relatively optically faint galaxies, when no color selection is applied. Conversely, when SDSS galaxies are split based on their color, we find that the correlation function of blue optical galaxies is practically indistinguishable from that of H I-selected galaxies. At the same time, SDSS galaxies with red colors are found to cluster significantly more than H I-selected galaxies, a fact that is evident in both the projected as well as the full two-dimensional correlation function. A cross-correlation analysis further reveals that gas-rich galaxies 'avoid' being located within ≈3 Mpc of optical galaxies with red colors. Next, we consider the clustering properties of halo samples selected from the Bolshoi ΛCDM simulation. A comparison with the clustering of ALFALFA galaxies suggests that galactic H I mass is not tightly related to host halo mass and that a sizable fraction of subhalos do not host H I galaxies. Lastly, we find that we can recover fairly well the correlation function of H I galaxies by just excluding halos with low spin parameter. This finding lends support to the hypothesis that halo spin plays a key role in determining the gas content of galaxies.« less

Comparison of stellar population model predictions using optical and infrared spectroscopy

NASA Astrophysics Data System (ADS)

Baldwin, C.; McDermid, R. M.; Kuntschner, H.; Maraston, C.; Conroy, C.

2018-02-01

We present Gemini/GNIRS cross-dispersed near-infrared spectra of 12 nearby early-type galaxies, with the aim of testing commonly used stellar population synthesis models. We select a subset of galaxies from the ATLAS3D sample which span a wide range of ages (single stellar population equivalent ages of 1-15 Gyr) at approximately solar metallicity. We derive star formation histories using four different stellar population synthesis models, namely those of Bruzual & Charlot, Conroy, Gunn & White, Maraston & Strömbäck and Vazdekis et al. We compare star formation histories derived from near-infrared spectra with those derived from optical spectra using the same models. We find that while all models agree in the optical, the derived star formation histories vary dramatically from model to model in the near-infrared. We find that this variation is largely driven by the choice of stellar spectral library, such that models including high-quality spectral libraries provide the best fits to the data, and are the most self-consistent when comparing optically derived properties with near-infrared ones. We also find the impact of age variation in the near-infrared to be subtle, and largely encoded in the shape of the continuum, meaning that the common approach of removing continuum information with a high-order polynomial greatly reduces our ability to constrain ages in the near-infrared.

Three-Dimensional Self-Assembled Photonic Crystal Waveguide

NASA Astrophysics Data System (ADS)

Baek, Kang-Hyun

Photonic crystals (PCs), two- or three-dimensionally periodic, artificial, and dielectric structures, have a specific forbidden band for electromagnetic waves, referred to as photonic bandgap (PBG). The PBG is analogous to the electronic bandgap in natural crystal structures with periodic atomic arrangement. A well-defined and embedded planar, line, or point defect within the PCs causes a break in its structural periodicity, and introduces a state in the PBG for light localization. It offers various applications in integrated optics and photonics including optical filters, sharp bending light guides and very low threshold lasers. Using nanofabrication processes, PCs of the 2-D slab-type and 3-D layer-by-layer structures have been investigated widely. Alternatively, simple and low-cost self-assembled PCs with full 3-D PBG, inverse opals, have been suggested. A template with face centered cubic closed packed structure, opal, may initially be built by self-assembly of colloidal spheres, and is selectively removed after infiltrating high refractive index materials into the interstitials of spheres. In this dissertation, the optical waveguides utilizing the 3-D self-assembled PCs are discussed. The waveguides were fabricated by microfabrication technology. For high-quality colloidal silica spheres and PCs, reliable synthesis, self-assembly, and characterization techniques were developed. Its theoretical and experimental demonstrations are provided and correlated. They suggest that the self-assembled PCs with PBG are feasible for the applications in integrated optics and photonics.

Multispectral glancing incidence X-ray telescope

NASA Technical Reports Server (NTRS)

Hoover, Richard B. (Inventor)

1990-01-01

A multispectral glancing incidence X-ray telescope is illustrated capable of broadband, high-resolution imaging of solar and stellar X-ray and extreme ultraviolet radiation sources which includes a primary optical system preferably of the Wolter I type having a primary mirror system (20, 22). The primary optical system further includes an optical axis (24) having a primary focus (F1) at which the incoming radiation is focused by the primary mirrors. A plurality of ellipsoidal mirrors (30a, 30b, 30cand 30d) are carried at an inclination to the optical axis behind the primary focus (F1). A rotating carrier (32) is provided on which the ellipsoidal mirrors are carried so that a desired one of the ellipsoidal mirrors may be selectively positioned in front of the incoming radiation beam (26). In the preferred embodiment, each of the ellipsoidal mirrors has an identical concave surface carrying a layered synthetic microstructure coating tailored to reflect a desired wavelength of 1.5 .ANG. or longer. Each of the identical ellipsoidal mirrors has a second focus (F2) at which a detector (16) is carried. Thus the different wavelength image is focused upon the detector irregardless of which mirror is positioned in front of the radiation beam. In this manner, a plurality of low wavelengths in a wavelength band generally less than 30 angstroms can be imaged with a high resolution.

Comparison of seven optical clearing methods for mouse brain

NASA Astrophysics Data System (ADS)

Wan, Peng; Zhu, Jingtan; Yu, Tingting; Zhu, Dan

2018-02-01

Recently, a variety of tissue optical clearing techniques have been developed to reduce light scattering for imaging deeper and three-dimensional reconstruction of tissue structures. Combined with optical imaging techniques and diverse labeling methods, these clearing methods have significantly promoted the development of neuroscience. However, most of the protocols were proposed aiming for specific tissue type. Though there are some comparison results, the clearing methods covered are limited and the evaluation indices are lack of uniformity, which made it difficult to select a best-fit protocol for clearing in practical applications. Hence, it is necessary to systematically assess and compare these clearing methods. In this work, we evaluated the performance of seven typical clearing methods, including 3DISCO, uDISCO, SeeDB, ScaleS, ClearT2, CUBIC and PACT, on mouse brain samples. First, we compared the clearing capability on both brain slices and whole-brains by observing brain transparency. Further, we evaluated the fluorescence preservation and the increase of imaging depth. The results showed that 3DISCO, uDISCO and PACT posed excellent clearing capability on mouse brains, ScaleS and SeeDB rendered moderate transparency, while ClearT2 was the worst. Among those methods, ScaleS was the best on fluorescence preservation, and PACT achieved the highest increase of imaging depth. This study is expected to provide important reference for users in choosing most suitable brain optical clearing method.

Optical telescope refocussing mechanism concept design on remote sensing satellite

NASA Astrophysics Data System (ADS)

Kuo, Jen-Chueh; Ling, Jer

2017-09-01

The optical telescope system in remote sensing satellite must be precisely aligned to obtain high quality images during its mission life. In practical, because the telescope mirrors could be misaligned due to launch loads, thermal distortion on supporting structures or hygroscopic distortion effect in some composite materials, the optical telescope system is often equipped with refocussing mechanism to re-align the optical elements while optical element positions are out of range during image acquisition. This paper is to introduce satellite Refocussing mechanism function model design development process and the engineering models. The design concept of the refocussing mechanism can be applied on either cassegrain type telescope or korsch type telescope, and the refocussing mechanism is located at the rear of the secondary mirror in this paper. The purpose to put the refocussing mechanism on the secondary mirror is due to its higher sensitivity on MTF degradation than other optical elements. There are two types of refocussing mechanism model to be introduced: linear type model and rotation type model. For the linear refocussing mechanism function model, the model is composed of ceramic piezoelectric linear step motor, optical rule as well as controller. The secondary mirror is designed to be precisely moved in telescope despace direction through refocussing mechanism. For the rotation refocussing mechanism function model, the model is assembled with two ceramic piezoelectric rotational motors around two orthogonal directions in order to adjust the secondary mirror attitude in tilt angle and yaw angle. From the validation test results, the linear type refocussing mechanism function model can be operated to adjust the secondary mirror position with minimum 500 nm resolution with close loop control. For the rotation type model, the attitude angle of the secondary mirror can be adjusted with the minimum 6 sec of arc resolution and 5°/sec of angle velocity.

Ultrafast nonlinear optofluidics in selectively liquid-filled photonic crystal fibers.

PubMed

Vieweg, M; Gissibl, T; Pricking, S; Kuhlmey, B T; Wu, D C; Eggleton, B J; Giessen, H

2010-11-22

Selective filling of photonic crystal fibers with different media enables a plethora of possibilities in linear and nonlinear optics. Using two-photon direct-laser writing we demonstrate full flexibility of individual closing of holes and subsequent filling of photonic crystal fibers with highly nonlinear liquids. We experimentally demonstrate solitonic supercontinuum generation over 600 nm bandwidth using a compact femtosecond oscillator as pump source. Encapsulating our fibers at the ends we realize a compact ultrafast nonlinear optofluidic device. Our work is fundamentally important to the field of nonlinear optics as it provides a new platform for investigations of spatio-temporal nonlinear effects and underpins new applications in sensing and communications. Selective filling of different linear and nonlinear liquids, metals, gases, gain media, and liquid crystals into photonic crystal fibers will be the basis of new reconfigurable and versatile optical fiber devices with unprecedented performance. Control over both temporal and spatial dispersion as well as linear and nonlinear coupling will lead to the generation of spatial-temporal solitons, so-called optical bullets.

A COMPARISON OF IN SITU AND MODELLED ESTIMATES OF SELECTED APPARENT OPTICAL PROPERTIES IN RESPONSE TO CHL A AND CDOM VARIABILITY IN THE COASTAL WATERS OF SOUTHERN NEW ENGLAND DURING SUMMER 1999

EPA Science Inventory

Chlorophyll a concentrations, colored dissolved organic matter (CDOM) absorption coefficients, and selected apparent optical properties (AOPs) of waters along the Western Passage of Narragansett Bay and adjoining Rhode Island Sound were determined from May -August 1999. Water sam...

Selective Removal of Natural Occlusal Caries by Coupling Near-infrared Imaging with a CO2 Laser

PubMed Central

Tao, You-Chen; Fried, Daniel

2011-01-01

Laser removal of dental hard tissue can be combined with optical, spectral or acoustic feedback systems to selectively ablate dental caries and restorative materials. Near-infrared (NIR) imaging has considerable potential for the optical discrimination of sound and demineralized tissue. Last year we successfully demonstrated that near-IR images can be used to guide a CO2 laser ablation system for the selective removal of artificial caries lesions on smooth surfaces. The objective of this study was to test the hypothesis that two-dimensional near-infrared images of natural occlusal caries can be used to guide a CO2 laser for selective removal. Two-dimensional NIR images were acquired at 1310-nm of extracted human molar teeth with occlusal caries. Polarization sensitive optical coherence tomography (PS-OCT) was also used to acquire depth-resolved images of the lesion areas. An imaging processing module was developed to analyze the NIR imaging output and generate optical maps that were used to guide a CO2 laser to selectively remove the lesions at a uniform depth. Post-ablation NIR images were acquired to verify caries removal. Based on the analysis of the NIR images, caries lesions were selectively removed with a CO2 laser while sound tissues were conserved. However, the removal rate varied markedly with the severity of decay and multiple passes were required for caries removal. These initial results are promising but indicate that the selective removal of natural caries is more challenging than the selective removal of artificial lesions due to varying tooth geometry, the highly variable organic/mineral ratio in natural lesions and more complicated lesion structure. PMID:21909225

Selective removal of natural occlusal caries by coupling near-infrared imaging with a CO II laser

NASA Astrophysics Data System (ADS)

Tao, You-Chen; Fried, Daniel

2008-02-01

Laser removal of dental hard tissue can be combined with optical, spectral or acoustic feedback systems to selectively ablate dental caries and restorative materials. Near-infrared (NIR) imaging has considerable potential for the optical discrimination of sound and demineralized tissue. Last year we successfully demonstrated that near-IR images can be used to guide a CO2 laser ablation system for the selective removal of artificial caries lesions on smooth surfaces. The objective of this study was to test the hypothesis that two-dimensional near-infrared images of natural occlusal caries can be used to guide a CO2 laser for selective removal. Two-dimensional NIR images were acquired at 1310-nm of extracted human molar teeth with occlusal caries. Polarization sensitive optical coherence tomography (PS-OCT) was also used to acquire depth-resolved images of the lesion areas. An imaging processing module was developed to analyze the NIR imaging output and generate optical maps that were used to guide a CO2 laser to selectively remove the lesions at a uniform depth. Post-ablation NIR images were acquired to verify caries removal. Based on the analysis of the NIR images, caries lesions were selectively removed with a CO2 laser while sound tissues were conserved. However, the removal rate varied markedly with the severity of decay and multiple passes were required for caries removal. These initial results are promising but indicate that the selective removal of natural caries is more challenging than the selective removal of artificial lesions due to varying tooth geometry, the highly variable organic/mineral ratio in natural lesions and more complicated lesion structure.

Selective Removal of Natural Occlusal Caries by Coupling Near-infrared Imaging with a CO(2) Laser.

PubMed

Tao, You-Chen; Fried, Daniel

2008-03-01

Laser removal of dental hard tissue can be combined with optical, spectral or acoustic feedback systems to selectively ablate dental caries and restorative materials. Near-infrared (NIR) imaging has considerable potential for the optical discrimination of sound and demineralized tissue. Last year we successfully demonstrated that near-IR images can be used to guide a CO(2) laser ablation system for the selective removal of artificial caries lesions on smooth surfaces. The objective of this study was to test the hypothesis that two-dimensional near-infrared images of natural occlusal caries can be used to guide a CO(2) laser for selective removal. Two-dimensional NIR images were acquired at 1310-nm of extracted human molar teeth with occlusal caries. Polarization sensitive optical coherence tomography (PS-OCT) was also used to acquire depth-resolved images of the lesion areas. An imaging processing module was developed to analyze the NIR imaging output and generate optical maps that were used to guide a CO(2) laser to selectively remove the lesions at a uniform depth. Post-ablation NIR images were acquired to verify caries removal. Based on the analysis of the NIR images, caries lesions were selectively removed with a CO(2) laser while sound tissues were conserved. However, the removal rate varied markedly with the severity of decay and multiple passes were required for caries removal. These initial results are promising but indicate that the selective removal of natural caries is more challenging than the selective removal of artificial lesions due to varying tooth geometry, the highly variable organic/mineral ratio in natural lesions and more complicated lesion structure.

Propagation of a general-type beam through a truncated fractional Fourier transform optical system.

PubMed

Zhao, Chengliang; Cai, Yangjian

2010-03-01

Paraxial propagation of a general-type beam through a truncated fractional Fourier transform (FRT) optical system is investigated. Analytical formulas for the electric field and effective beam width of a general-type beam in the FRT plane are derived based on the Collins formula. Our formulas can be used to study the propagation of a variety of laser beams--such as Gaussian, cos-Gaussian, cosh-Gaussian, sine-Gaussian, sinh-Gaussian, flat-topped, Hermite-cosh-Gaussian, Hermite-sine-Gaussian, higher-order annular Gaussian, Hermite-sinh-Gaussian and Hermite-cos-Gaussian beams--through a FRT optical system with or without truncation. The propagation properties of a Hermite-cos-Gaussian beam passing through a rectangularly truncated FRT optical system are studied as a numerical example. Our results clearly show that the truncated FRT optical system provides a convenient way for laser beam shaping.

The application of digital image analysis for blood typing: the comparison of anti-A and anti-B monoclonal antibodies activity with standard hemagglutinating sera

NASA Astrophysics Data System (ADS)

Medvedeva, Maria F.; Doubrovski, Valery A.

2017-03-01

The resolution of the acousto-optical method for blood typing was estimated experimentally by means of two types of reagents: monoclonal antibodies and standard hemagglutinating sera. The peculiarity of this work is the application of digital photo images processing by pixel analysis previously proposed by the authors. The influence of the concentrations of reagents, of blood sample, which is to be tested, as well as of the duration of the ultrasonic action on the biological object upon the resolution of acousto-optical method were investigated. The optimal experimental conditions to obtain maximum of the resolution of the acousto-optical method were found, it creates the prerequisites for a reliable blood typing. The present paper is a further step in the development of acousto-optical method for determining human blood groups.

Third harmonic frequency generation by type-I critically phase-matched LiB3O5 crystal by means of optically active quartz crystal.

PubMed

Gapontsev, Valentin P; Tyrtyshnyy, Valentin A; Vershinin, Oleg I; Davydov, Boris L; Oulianov, Dmitri A

2013-02-11

We present a method of third harmonic generation at 355 nm by frequency mixing of fundamental and second harmonic radiation of an ytterbium nanosecond pulsed all-fiber laser in a type-I phase-matched LiB(3)O(5) (LBO) crystal where originally orthogonal polarization planes of the fundamental and second harmonic beams are aligned by an optically active quartz crystal. 8 W of ultraviolet light at 355 nm were achieved with 40% conversion efficiency from 1064 nm radiation. The conversion efficiency obtained in a type-I phase-matched LBO THG crystal was 1.6 times higher than the one achieved in a type-II LBO crystal at similar experimental conditions. In comparison to half-wave plates traditionally used for polarization alignment the optically active quartz crystal has much lower temperature dependence and requires simpler optical alignment.

Fuel level sensor based on polymer optical fiber Bragg gratings for aircraft applications

NASA Astrophysics Data System (ADS)

Marques, C. A. F.; Pospori, A.; Sáez-Rodríguez, D.; Nielsen, K.; Bang, O.; Webb, D. J.

2016-04-01

Safety in civil aviation is increasingly important due to the increase in flight routes and their more challenging nature. Like other important systems in aircraft, fuel level monitoring is always a technical challenge. The most frequently used level sensors in aircraft fuel systems are based on capacitive, ultrasonic and electric techniques, however they suffer from intrinsic safety concerns in explosive environments combined with issues relating to reliability and maintainability. In the last few years, optical fiber liquid level sensors (OFLLSs) have been reported to be safe and reliable and present many advantages for aircraft fuel measurement. Different OFLLSs have been developed, such as the pressure type, float type, optical radar type, TIR type and side-leaking type. Amongst these, many types of OFLLSs based on fiber gratings have been demonstrated. However, these sensors have not been commercialized because they exhibit some drawbacks: low sensitivity, limited range, long-term instability, or limited resolution. In addition, any sensors that involve direct interaction of the optical field with the fuel (either by launching light into the fuel tank or via the evanescent field of a fiber-guided mode) must be able to cope with the potential build up of contamination - often bacterial - on the optical surface. In this paper, a fuel level sensor based on microstructured polymer optical fiber Bragg gratings (mPOFBGs), including poly (methyl methacrylate) (PMMA) and TOPAS fibers, embedded in diaphragms is investigated in detail. The mPOFBGs are embedded in two different types of diaphragms and their performance is investigated with aviation fuel for the first time, in contrast to our previous works, where water was used. Our new system exhibits a high performance when compared with other previously published in the literature, making it a potentially useful tool for aircraft fuel monitoring.

FIBER AND INTEGRATED OPTICS: New type of heterogeneous nanophotonic silicon-on-insulator optical waveguides

NASA Astrophysics Data System (ADS)

Tsarev, Andrei V.

2007-08-01

A new type of optical waveguides in silicon-on-insulator nanostructures is proposed and studied. Their optical properties are simulated by the beam propagation method and discussed. A new design in the form of heterogeneous waveguide structures is based on the production of additionally heavily doped p+-regions on the sides of a multimode stripe waveguide (the silicon core cross section is ~200 nm × 16 μm). Such doping provides the 'single-mode' behaviour of the heterogeneous waveguide due to the decrease in the optical losses for the fundamental mode and increase in losses for higher-order modes. Single-mode heterogeneous waveguides can be used as base waveguides in photonic and integrated optical elements.

Selected developments in laser wire stripping. [cutting insulation from aerospace-type wires and cables

NASA Technical Reports Server (NTRS)

1977-01-01

The operation of mechanical and thermal strippers and the early development of laser wire strippers are reviewed. NASA sponsored development of laser wire stripping for space shuttle includes bench-type strippers as well as an advanced portable hand-held stripper which incorporates a miniaturized carbon dioxide laser and a rotating optics unit with a gas-jet assist and debris exhaust. Drives and controls girdle the wire and slit the remaining slug without manual assistance. This unit can strip wire sizes 26 through 12 gage. A larger-capacity hand-held unit for wire sizes through 1/0 gage was built using a neodynium-doped yttrium aluminum garnet (Nd:YAG) laser. The hand-held units have a flexible umbilical cable to an accompanying cart that carries the power supply, gas supply, cooling unit, and the controls.

Compact light-emitting-diode sun photometer for atmospheric optical depth measurements.

PubMed

Acharya, Y B; Jayaraman, A; Ramachandran, S; Subbaraya, B H

1995-03-01

A new compact light-emitting diode (LED) sun photometer, in which a LED is used as a spectrally selective photodetector as well as a nonlinear feedback element in the operational amplifier, has been developed. The output voltage that is proportional to the logarithm of the incident solar intensity permits the direct measurement of atmospheric optical depths in selected spectral bands. Measurements made over Ahmedabad, India, show good agreement, within a few percent, of optical depths derived with a LED as a photodetector in a linear mode and with a LED as both a photodetector and a feedback element in an operational amplifier in log mode. The optical depths are also found to compare well with those obtained simultaneously with a conventional filter photometer.

Enhancement of carrier lifetimes in type-II quantum dot/quantum well hybrid structures

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

Couto, O. D. D., E-mail: odilon@ifi.unicamp.br; Almeida, P. T. de; Santos, G. E. dos

We investigate optical transitions and carrier dynamics in hybrid structures containing type-I GaAs/AlGaAs quantum wells (QWs) and type-II GaSb/AlGaAs quantum dots (QDs). We show that the optical recombination of photocreated electrons confined in the QWs with holes in the QDs and wetting layer can be modified according to the QW/QD spatial separation. In particular, for low spacer thicknesses, the QW optical emission can be suppressed due to the transference of holes from the QW to the GaSb layer, favoring the optical recombination of spatially separated carriers, which can be useful for optical memory and solar cell applications. Time-resolved photoluminescence (PL)more » measurements reveal non-exponential recombination dynamics. We demonstrate that the PL transients can only be quantitatively described by considering both linear and quadratic terms of the carrier density in the bimolecular recombination approximation for type-II semiconductor nanostructures. We extract long exciton lifetimes from 700 ns to 5 μs for QDs depending on the spacer layer thickness.« less

Programmable Iterative Optical Image And Data Processing

NASA Technical Reports Server (NTRS)

Jackson, Deborah J.

1995-01-01

Proposed method of iterative optical image and data processing overcomes limitations imposed by loss of optical power after repeated passes through many optical elements - especially, beam splitters. Involves selective, timed combination of optical wavefront phase conjugation and amplification to regenerate images in real time to compensate for losses in optical iteration loops; timing such that amplification turned on to regenerate desired image, then turned off so as not to regenerate other, undesired images or spurious light propagating through loops from unwanted reflections.

Seismic damage identification for steel structures using distributed fiber optics.

PubMed

Hou, Shuang; Cai, C S; Ou, Jinping

2009-08-01

A distributed fiber optic monitoring methodology based on optic time domain reflectometry technology is developed for seismic damage identification of steel structures. Epoxy with a strength closely associated to a specified structure damage state is used for bonding zigzagged configured optic fibers on the surfaces of the structure. Sensing the local deformation of the structure, the epoxy modulates the signal change within the optic fiber in response to the damage state of the structure. A monotonic loading test is conducted on a steel specimen installed with the proposed sensing system using selected epoxy that will crack at the designated strain level, which indicates the damage of the steel structure. Then, using the selected epoxy, a varying degree of cyclic loading amplitudes, which is associated with different damage states, is applied on a second specimen. The test results show that the specimen's damage can be identified by the optic sensors, and its maximum local deformation can be recorded by the sensing system; moreover, the damage evolution can also be identified.

Theory of optical absorption by interlayer excitons in transition metal dichalcogenide heterobilayers

NASA Astrophysics Data System (ADS)

Wu, Fengcheng; Lovorn, Timothy; MacDonald, A. H.

2018-01-01

We present a theory of optical absorption by interlayer excitons in a heterobilayer formed from transition metal dichalcogenides. The theory accounts for the presence of small relative rotations that produce a momentum shift between electron and hole bands located in different layers, and a moiré pattern in real space. Because of the momentum shift, the optically active interlayer excitons are located at the moiré Brillouin zone's corners, instead of at its center, and would have elliptical optical selection rules if the individual layers were translationally invariant. We show that the exciton moiré potential energy restores circular optical selection rules by coupling excitons with different center of mass momenta. A variety of interlayer excitons with both senses of circular optical activity, and energies that are tunable by twist angle, are present at each valley. The lowest energy exciton states are generally localized near the exciton potential energy minima. We discuss the possibility of using the moiré pattern to achieve scalable two-dimensional arrays of nearly identical quantum dots.

Optical design of common aperture, common focal plane, multispectral optics for military applications

NASA Astrophysics Data System (ADS)

Thompson, Nicholas Allan

2013-06-01

With recent developments in multispectral detector technology, the interest in common aperture, common focal plane multispectral imaging systems is increasing. Such systems are particularly desirable for military applications, where increased levels of target discrimination and identification are required in cost-effective, rugged, lightweight systems. During the optical design of dual waveband or multispectral systems, the options for material selection are limited. This selection becomes even more restrictive for military applications, where material resilience, thermal properties, and color correction must be considered. We discuss the design challenges that lightweight multispectral common aperture systems present, along with some potential design solutions. Consideration is given to material selection for optimum color correction, as well as material resilience and thermal correction. This discussion is supported using design examples currently in development at Qioptiq.

Transparent conductor-embedding nanocones for selective emitters: optical and electrical improvements of Si solar cells

PubMed Central

Kim, Joondong; Yun, Ju-Hyung; Kim, Hyunyub; Cho, Yunae; Park, Hyeong-Ho; Kumar, M. Melvin David; Yi, Junsin; Anderson, Wayne A.; Kim, Dong-Wook

2015-01-01

Periodical nanocone-arrays were employed in an emitter region for high efficient Si solar cells. Conventional wet-etching process was performed to form the nanocone-arrays for a large area, which spontaneously provides the graded doping features for a selective emitter. This enables to lower the electrical contact resistance and enhances the carrier collection due to the high electric field distribution through a nanocone. Optically, the convex-shaped nanocones efficiently reduce light-reflection and the incident light is effectively focused into Si via nanocone structure, resulting in an extremely improved the carrier collection performances. This nanocone-arrayed selective emitter simultaneously satisfies optical and electrical improvement. We report the record high efficiency of 16.3% for the periodically nanoscale patterned emitter Si solar cell. PMID:25787933

Transparent conductor-embedding nanocones for selective emitters: optical and electrical improvements of Si solar cells.

PubMed

Kim, Joondong; Yun, Ju-Hyung; Kim, Hyunyub; Cho, Yunae; Park, Hyeong-Ho; Kumar, M Melvin David; Yi, Junsin; Anderson, Wayne A; Kim, Dong-Wook

2015-03-19

Periodical nanocone-arrays were employed in an emitter region for high efficient Si solar cells. Conventional wet-etching process was performed to form the nanocone-arrays for a large area, which spontaneously provides the graded doping features for a selective emitter. This enables to lower the electrical contact resistance and enhances the carrier collection due to the high electric field distribution through a nanocone. Optically, the convex-shaped nanocones efficiently reduce light-reflection and the incident light is effectively focused into Si via nanocone structure, resulting in an extremely improved the carrier collection performances. This nanocone-arrayed selective emitter simultaneously satisfies optical and electrical improvement. We report the record high efficiency of 16.3% for the periodically nanoscale patterned emitter Si solar cell.

Utilization of a new optical sensor unit to monitor the electrochemical elimination of selected dyes in water

NASA Astrophysics Data System (ADS)

Valica, M.; Černá, T.; Hostin, S.

2017-10-01

This paper presents results obtained by developed optical sensor, which consist from multi-wavelength LED light source and two photodetectors capable of measuring the change in optical signal along two different optical paths (absorbance and reflectance measurements). Arduino microcomputer was used for light source management and optical signal data measuring and recording. Analytical validation of developed optical sensor is presented in this paper. The performance of the system has been tested with varying water solution of dyes (malachite green, methyl orange, trypan red). These results show strong correlations between the optical signal response and colour change from the dyes. Sensor was used for continual in-situ monitoring of electrochemical elimination of selected dyes (current density 15.7 mA cm-2, electrolyte volume 4 L and NaCl concentration 2 g L-1). Maximum decolorization level varies with each dye. For malachite green was obtain 92,7 % decolorization (25 min); methyl orange 90,8% (8,5 min) and trypan red 84,7% decolorization after 33 min of electrochemical treatment.

Electro-optical tunable waveguide embedded multiscan Bragg gratings in lithium niobate by direct femtosecond laser writing.

PubMed

Kroesen, Sebastian; Horn, Wolfgang; Imbrock, Jörg; Denz, Cornelia

2014-09-22

optical tunable Bragg gratings in lithium niobate fabricated by direct femtosecond laser writing. The hybrid design that consists of a circular type-II waveguide and a multiscan type-I Bragg grating exhibits low loss ordinary and extraordinary polarized guiding as well as narrowband reflections in the c-band of optical communications. High bandwidth tunability of more than a peak width and nearly preserved electro-optic coefficients of r(13) = 7.59 pm V(-1) and r(33) = 23.21 pm V(-1) are demonstrated.

Design and manufacture of imaging time-of-propagation optics

NASA Astrophysics Data System (ADS)

Albrecht, Mike; Fast, James; Schwartz, Alan

2016-09-01

There are several challenges associated with the design and manufacture of the optics required for the imaging time-of- propagation detector constructed for the Belle II particle physics experiment. This detector uses Cherenkov light radiated in quartz bars to identify subatomic particles: pions, kaons, and protons. The optics are physically large (125 cm x 45 cm x 2 cm bars and 45 cm x 10 cm x 5 cm prisms), all surfaces are optically polished, and there is very little allowance for chamfers or surface defects. In addition to the optical challenges, there are several logistical and handling challenges associated with measuring, assembling, cleaning, packaging, and shipping these delicate precision optics. This paper describes a collaborative effort between Pacific Northwest National Laboratory, the University of Cincinnati, and ZYGO Corporation for the design and manufacture of 48 fused silica optics (30 bars and 18 prisms) for the iTOP Detector. Details of the iTOP detector design that drove the challenging optical requirements are provided, along with material selection considerations. Since the optics are so large, precise, and delicate, special care had to be given to the selection of a manufacturing process capable of achieving the challenging optical and surface defect requirements on such large and high-aspect-ratio (66:1) components. A brief update on the current status and performance of these optics is also provided.

Plasmonic-based colorimetric and spectroscopic discrimination of acetic and butyric acids produced by different types of Escherichia coli through the different assembly structures formation of gold nanoparticles.

PubMed

La, Ju A; Lim, Sora; Park, Hyo Jeong; Heo, Min-Ji; Sang, Byoung-In; Oh, Min-Kyu; Cho, Eun Chul

2016-08-24

We present a plasmonic-based strategy for the colourimetric and spectroscopic differentiation of various organic acids produced by bacteria. The strategy is based on our discovery that particular concentrations of dl-lactic, acetic, and butyric acids induce different assembly structures, colours, and optical spectra of gold nanoparticles. We selected wild-type (K-12 W3110) and genetically-engineered (JHL61) Escherichia coli (E. coli) that are known to primarily produce acetic and butyric acid, respectively. Different assembly structures and optical properties of gold nanoparticles were observed when different organic acids, obtained after the removal of acid-producing bacteria, were mixed with gold nanoparticles. Moreover, at moderate cell concentrations of K-12 W3110 E. coli, which produce sufficient amounts of acetic acid to induce the assembly of gold nanoparticles, a direct estimate of the number of bacteria was possible based on time-course colour change observations of gold nanoparticle aqueous suspensions. The plasmonic-based colourimetric and spectroscopic methods described here may enable onsite testing for the identification of organic acids produced by bacteria and the estimation of bacterial numbers, which have applications in health and environmental sciences. Copyright © 2016 Elsevier B.V. All rights reserved.

X-ray selected stars in HRC and BHRC catalogues

NASA Astrophysics Data System (ADS)

Mickaelian, A. M.; Paronyan, G. M.

2014-12-01

A joint HRC/BHRC Catalogue has been created based on merging of Hamburg ROSAT Catalogue (HRC) and Byurakan Hamburg ROSAT Catalogue (BHRC). Both have been made by optical identifications of X-ray sources based on low-dispersion spectra of the Hamburg Quasar Survey (HQS) using ROSAT Catalogues. As a result, the largest sample of 8132 (5341+2791) optically identified X-ray sources was created having count rate (CR) of photons ≤ 0.04 ct/s in the area with galactic latitudes |b|≤ 20° and declinations d≤ 0°.There are 4253 AGN, 492 galaxies, 1800 stars and 1587 unknown objects in the sample. All stars have been found in GSC 2.3.2, as well as most of them are in GALEX, USNO-B1.0, 2MASS and WISE catalogues. In addition, 1429 are in SDSS DR9 and 204 have SDSS spectra. For these stars we have carried out spectral classification and along with the bright stars, many new cataclysmic variables (CV), white dwarfs (WD) and late-type stars (K-M and C) have been revealed. For all stars, statistical studies of their multiwavelength properties have been made. An attempt to find a connection between the radiation fluxes in different bands for different types of sources, and identify their characteristics was made as well.

International Ultraviolet Explorer Observations of Wolf-Rayet Binaries: Wind Structures. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Koenigsberger, G.

1983-01-01

Spectra of six WN + OB Wolf-Rayet systems obtained with the IUE are analyzed for phase-dependent variations. Periodic variability at emission-line frequencies is detected in V444 Cyg, HD 90657, HD 211853, HD 186943 and HD 94546 on low dispersion SWP images. No changes in the low dispersion spectra of HD 193077 are apparent. We find the variations in the UV to be similar in nature to those observed in optical spectra of various WR sources. That is, there is a strengthening of absorption components in P Cygni-type features at orbital phases in which the O-star is behind the WR wind. With the aid of a computer code which models this type of variations, and through a comparison with HD 193077, the dominant mechanism producing the variations is shown to be selective atmospheric eclipses of the O-star by the WR wind. Based on this interpretation, a straightforward technique is applied to the line of N IV 1718, by which an optical depth distribution in the WN winds of the form tau varies as r(-1) is derived for 16 r 66 solar radii. Phase-dependent variations in the width of the C IV 1550 absorption component in V444 Cyg, HD 90657 and HD 211853 are interpretated as wind-wind collision effects.

Second-Order Nonlinear Optical Dendrimers and Dendronized Hyperbranched Polymers.

PubMed

Tang, Runli; Li, Zhen

2017-01-01

Second-order nonlinear optical (NLO) dendrimers with a special topological structure were regarded as the most promising candidates for practical applications in the field of optoelectronic materials. Dendronized hyperbranched polymers (DHPs), a new type of polymers with dendritic structures, proposed and named by us recently, demonstrated interesting properties and some advantages over other polymers. Some of our work concerning these two types of polymers are presented herein, especially focusing on the design idea and structure-property relationship. To enhance their comprehensive NLO performance, dendrimers were designed and synthesized by adjusting their isolation mode, increasing the number of the dendritic generation, modifying their topological structure, introducing isolation chromophores, and utilizing the Ar-Ar F self-assembly effect. To make full use of the advantages of both the structural integrity of dendrimers and the convenient one-pot synthesis of hyperbranched polymers, DHPs were explored by utilizing low-generation dendrons as big monomers to construct hyperbranched polymers. These selected works could provide valuable information to deeply understand the relationship between the structure and properties of functional polymers with dendritic structures, but not only limited to the NLO ones, and might contribute much to the further development of functional polymers with rational design. © 2017 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.