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Sample records for optically activated high

  1. Magneto-Optical Activity in High Index Dielectric Nanoantennas

    PubMed Central

    de Sousa, N.; Froufe-Pérez, L. S.; Sáenz, J. J.; García-Martín, A.

    2016-01-01

    The magneto-optical activity, namely the polarization conversion capabilities of high-index, non-absorbing, core-shell dielectric nanospheres is theoretically analyzed. We show that, in analogy with their plasmonic counterparts, the polarization conversion in resonant dielectric particles is linked to the amount of electromagnetic field probing the magneto-optical material in the system. However, in strong contrast with plasmon nanoparticles, due to the peculiar distribution of the internal fields in resonant dielectric spheres, the magneto-optical response is fully governed by the magnetic (dipolar and quadrupolar) resonances with little effect of the electric ones. PMID:27488903

  2. Magneto-Optical Activity in High Index Dielectric Nanoantennas.

    PubMed

    de Sousa, N; Froufe-Pérez, L S; Sáenz, J J; García-Martín, A

    2016-01-01

    The magneto-optical activity, namely the polarization conversion capabilities of high-index, non-absorbing, core-shell dielectric nanospheres is theoretically analyzed. We show that, in analogy with their plasmonic counterparts, the polarization conversion in resonant dielectric particles is linked to the amount of electromagnetic field probing the magneto-optical material in the system. However, in strong contrast with plasmon nanoparticles, due to the peculiar distribution of the internal fields in resonant dielectric spheres, the magneto-optical response is fully governed by the magnetic (dipolar and quadrupolar) resonances with little effect of the electric ones.

  3. Magneto-Optical Activity in High Index Dielectric Nanoantennas

    NASA Astrophysics Data System (ADS)

    de Sousa, N.; Froufe-Pérez, L. S.; Sáenz, J. J.; García-Martín, A.

    2016-08-01

    The magneto-optical activity, namely the polarization conversion capabilities of high-index, non-absorbing, core-shell dielectric nanospheres is theoretically analyzed. We show that, in analogy with their plasmonic counterparts, the polarization conversion in resonant dielectric particles is linked to the amount of electromagnetic field probing the magneto-optical material in the system. However, in strong contrast with plasmon nanoparticles, due to the peculiar distribution of the internal fields in resonant dielectric spheres, the magneto-optical response is fully governed by the magnetic (dipolar and quadrupolar) resonances with little effect of the electric ones.

  4. Magneto-Optical Activity in High Index Dielectric Nanoantennas.

    PubMed

    de Sousa, N; Froufe-Pérez, L S; Sáenz, J J; García-Martín, A

    2016-01-01

    The magneto-optical activity, namely the polarization conversion capabilities of high-index, non-absorbing, core-shell dielectric nanospheres is theoretically analyzed. We show that, in analogy with their plasmonic counterparts, the polarization conversion in resonant dielectric particles is linked to the amount of electromagnetic field probing the magneto-optical material in the system. However, in strong contrast with plasmon nanoparticles, due to the peculiar distribution of the internal fields in resonant dielectric spheres, the magneto-optical response is fully governed by the magnetic (dipolar and quadrupolar) resonances with little effect of the electric ones. PMID:27488903

  5. Efficient high repetition rate electro-optic Q-switched laser with an optically active langasite crystal.

    PubMed

    Ma, Shihui; Yu, Haohai; Zhang, Huaijin; Han, Xuekun; Lu, Qingming; Ma, Changqin; Boughton, Robert I; Wang, Jiyang

    2016-01-01

    With an optically active langasite (LGS) crystal as the electro-optic Q-switch, we demonstrate an efficient Q-switched laser with a repetition rate of 200 kHz. Based on the theoretical analysis of the interaction between optical activity and electro-optic property, the optical activity of the crystal has no influence on the birefringence during Q-switching if the quarter wave plate used was rotated to align with the polarization direction. With a Nd:LuVO4 crystal possessing a large emission cross-section and a short fluorescence lifetime as the gain medium, a stable LGS Q-switched laser was designed with average output power of 4.39 W, corresponding to a slope efficiency of 29.4% and with a minimum pulse width of 5.1 ns. This work represents the highest repetition rate achieved so far in a LGS Q-switched laser and it can provide a practical Q-switched laser with a tunable high repetition rates for many applications, such as materials processing, laser ranging, medicine, military applications, biomacromolecule materials, remote sensing, etc.

  6. Efficient high repetition rate electro-optic Q-switched laser with an optically active langasite crystal

    PubMed Central

    Ma, Shihui; Yu, Haohai; Zhang, Huaijin; Han, Xuekun; Lu, Qingming; Ma, Changqin; Boughton, Robert I.; Wang, Jiyang

    2016-01-01

    With an optically active langasite (LGS) crystal as the electro-optic Q-switch, we demonstrate an efficient Q-switched laser with a repetition rate of 200 kHz. Based on the theoretical analysis of the interaction between optical activity and electro-optic property, the optical activity of the crystal has no influence on the birefringence during Q-switching if the quarter wave plate used was rotated to align with the polarization direction. With a Nd:LuVO4 crystal possessing a large emission cross-section and a short fluorescence lifetime as the gain medium, a stable LGS Q-switched laser was designed with average output power of 4.39 W, corresponding to a slope efficiency of 29.4% and with a minimum pulse width of 5.1 ns. This work represents the highest repetition rate achieved so far in a LGS Q-switched laser and it can provide a practical Q-switched laser with a tunable high repetition rates for many applications, such as materials processing, laser ranging, medicine, military applications, biomacromolecule materials, remote sensing, etc. PMID:27461819

  7. Efficient high repetition rate electro-optic Q-switched laser with an optically active langasite crystal

    NASA Astrophysics Data System (ADS)

    Ma, Shihui; Yu, Haohai; Zhang, Huaijin; Han, Xuekun; Lu, Qingming; Ma, Changqin; Boughton, Robert I.; Wang, Jiyang

    2016-07-01

    With an optically active langasite (LGS) crystal as the electro-optic Q-switch, we demonstrate an efficient Q-switched laser with a repetition rate of 200 kHz. Based on the theoretical analysis of the interaction between optical activity and electro-optic property, the optical activity of the crystal has no influence on the birefringence during Q-switching if the quarter wave plate used was rotated to align with the polarization direction. With a Nd:LuVO4 crystal possessing a large emission cross-section and a short fluorescence lifetime as the gain medium, a stable LGS Q-switched laser was designed with average output power of 4.39 W, corresponding to a slope efficiency of 29.4% and with a minimum pulse width of 5.1 ns. This work represents the highest repetition rate achieved so far in a LGS Q-switched laser and it can provide a practical Q-switched laser with a tunable high repetition rates for many applications, such as materials processing, laser ranging, medicine, military applications, biomacromolecule materials, remote sensing, etc.

  8. Efficient high repetition rate electro-optic Q-switched laser with an optically active langasite crystal.

    PubMed

    Ma, Shihui; Yu, Haohai; Zhang, Huaijin; Han, Xuekun; Lu, Qingming; Ma, Changqin; Boughton, Robert I; Wang, Jiyang

    2016-01-01

    With an optically active langasite (LGS) crystal as the electro-optic Q-switch, we demonstrate an efficient Q-switched laser with a repetition rate of 200 kHz. Based on the theoretical analysis of the interaction between optical activity and electro-optic property, the optical activity of the crystal has no influence on the birefringence during Q-switching if the quarter wave plate used was rotated to align with the polarization direction. With a Nd:LuVO4 crystal possessing a large emission cross-section and a short fluorescence lifetime as the gain medium, a stable LGS Q-switched laser was designed with average output power of 4.39 W, corresponding to a slope efficiency of 29.4% and with a minimum pulse width of 5.1 ns. This work represents the highest repetition rate achieved so far in a LGS Q-switched laser and it can provide a practical Q-switched laser with a tunable high repetition rates for many applications, such as materials processing, laser ranging, medicine, military applications, biomacromolecule materials, remote sensing, etc. PMID:27461819

  9. Active compensation of flexure on the High-Resolution Optical Spectrograph for Gemini

    NASA Astrophysics Data System (ADS)

    D'Arrigo, P.; Diego, Francisco; Walker, David D.

    1997-03-01

    Gravity-induced flexure has been a long-standing challenge in Cassegrain spectrographs at 4-meter class telescopes; it is the more so at the scale of 8-meter telescopes. This is of particular concern for the Gemini high resolution optical spectrograph, which will be Cassegrain-mounted for its routine mode of operation. In this paper we address the general flexure problem, and how to solve it with the use of active optics. We also present the results of an experimental active flexure compensation system for the ISIS (intermediate- dispersion spectroscopic and imaging system) spectrograph on the 4.2 m William Herschel Telescope (WHT). This instrument, called ISAAC (ISIS spectrograph automatic active collimator), is based on the concept of active correction, where spectrum drifts, due to the spectrograph flexing under the effect of gravity, are compensated by the movement of an active optical element (in this case a fine steering tip-tilt collimator mirror). The experiment showed that active compensation can reduce flexure down to less than 3 micrometer over four hours of telescope motions, dramatically improving the spectrograph performance. The results of the experiment are used to discuss a flexure compensation system for the high resolution optical spectrograph (HROS) for the 8 m Gemini telescope.

  10. Optical design of an all-reflecting, high resolution camera for active-optics on ground-based telescopes

    NASA Astrophysics Data System (ADS)

    Richardson, E. H.; Morbey, C. L.

    Optical designs of high-resolution all-mirror cameras for the active optics of the 3.6-m Canada-France-Hawaii Telescope (CFHT) with classical optics (a paraboloidal primary), and the 2.2-m University of Hawaii telescope with Ritchey-Chretien (R-C) optics (a hyperboloidal primary), are presented. An oblate spheroid is used to produce longer focal ratios in the R-C telescope, lessening its disadvantage of a very small field of good definition at focal ratios longer than the optimized secondary focal ratio. Unlike the R-C telescope, the CFHT is not coma-free, and the prolate spheroid works well as its tertiary mirror. In the present camera design, the scale at the final focus is such that 0.25 arcsec covers 0.065 mm in order to match the resolution of the available detector. These cameras are off-axis, resulting in a slight change of magnification with the field rotation of alt-azimuth telescopes.

  11. High-density active optical cable: from a new concept to a prototype

    NASA Astrophysics Data System (ADS)

    Wohlfeld, Denis; Lemke, Frank; Froening, Holger; Schenk, Sven; Bruening, Ulrich

    2011-01-01

    Evolution in high performance computing (HPC) leads to increasing demands on bandwidth, connectivity and flexibility. Active optical cables (AOC) are of special interest, combining the benefits of electrical connectors and optical transmission. Optimization and development of AOC solutions requires enhancements concerning different technology barriers. Area and volume occupied by connectors is of special interest within HPC networks. This led to the development of a 12x AOC for the mini-HT connector creating the densest AOC available. In order to integrate electrical optical conversion into a module not higher than 3 mm, a new concept of coupling fibers to VCSELs or photodiodes had to be developed. This unique concept is based on a direct replication process of an integrated fiber coupler consisting of a 90° light deflecting and focusing mirror, a fiber guiding structure, and a fiber funnel. The integrated fiber coupler is directly replicated on top of active components, reducing the distance between active components and fibers to a minimum, thus providing a highly efficient light coupling. As AOC prototype, multi-chipmodules (MCM) including the complete electrical to optical conversion for send and receive connected by two 12x fiber ribbons have been developed. The paper presents the integrated fiber coupling technique and also design and measurement data of the prototype.

  12. High-temperature optically activated GaAs power switching for aircraft digital electronic control

    NASA Technical Reports Server (NTRS)

    Berak, J. M.; Grantham, D. H.; Swindal, J. L.; Black, J. F.; Allen, L. B.

    1983-01-01

    Gallium arsenide high-temperature devices were fabricated and assembled into an optically activated pulse-width-modulated power control for a torque motor typical of the kinds used in jet engine actuators. A bipolar heterojunction phototransistor with gallium aluminum arsenide emitter/window, a gallium arsenide junction field-effect power transistor and a gallium arsenide transient protection diode were designed and fabricated. A high-temperature fiber optic/phototransistor coupling scheme was implemented. The devices assembled into the demonstrator were successfully tested at 250 C, proving the feasibility of actuator-located switching of control power using optical signals transmitted by fibers. Assessments of the efficiency and technical merits were made for extension of this high-temperature technology to local conversion of optical power to electrical power and its control at levels useful for driving actuators. Optical power sources included in the comparisons were an infrared light-emitting diode, an injection laser diode, tungsten-halogen lamps and arc lamps. Optical-to-electrical power conversion was limited to photovoltaics located at the actuator. Impedance matching of the photovoltaic array to the load was considered over the full temperature range, -55 C to 260 C. Loss of photovoltaic efficiency at higher temperatures was taken into account. Serious losses in efficiency are: (1) in the optical source and the cooling which they may require in the assumed 125 C ambient, (2) in the decreased conversion efficiency of the gallium arsenide photovoltaic at 260 C, and (3) in impedance matching. Practical systems require improvements in these areas.

  13. High-power fiber optic cable with integrated active sensors for live process monitoring

    NASA Astrophysics Data System (ADS)

    Blomster, Ola; Blomqvist, Mats; Bergstrand, Hans; Pålsson, Magnus

    2012-03-01

    In industrial applications using high-brilliance lasers at power levels up to and exceeding 20 kW and similarly direct diode lasers of 10 kW, there is an increasing demand to continuously monitor component status even in passive components such as fiber-optic cables. With fiber-optic cables designed according to the European Automotive Industry fiber standard interface there is room for integrating active sensors inside the connectors. In this paper we present the integrated active sensors in the new Optoskand QD fiber-optic cable designed to handle extreme levels of power losses, and how these sensors can be employed in industrial manufacturing. The sensors include photo diodes for detection of scattered light inside the fiber connector, absolute temperature of the fiber connector, difference in temperature of incoming and outgoing cooling water, and humidity measurement inside the fiber connector. All these sensors are connected to the fiber interlock system, where interlock break enable functions can be activated when measured signals are higher than threshold levels. It is a very fast interlock break system as the control of the signals is integrated in the electronics inside the fiber connector. Also, since all signals can be logged it is possible to evaluate what happened inside the connector before the interlock break instance. The communication to the fiber-optic connectors is via a CAN interface. Thus it is straightforward to develop the existing laser host control to also control the CAN-messages from the QD sensors.

  14. All optical active high decoder using integrated 2D square lattice photonic crystals

    NASA Astrophysics Data System (ADS)

    Moniem, Tamer A.

    2015-11-01

    The paper introduces a novel all optical active high 2 × 4 decoder based on 2D photonic crystals (PhC) of silicon rods with permittivity of ε = 10.1 × 10-11 farad/m. The main structure of optical decoder is designed using a combination of five nonlinear photonic crystal ring resonator, set of T-type waveguide, and line defect of Y and T branch splitters. The proposed structure has two logic input ports, four output ports, and one bias input port. The total size of the proposed 2 × 4 decoder is equal to 40 μm × 38 μm. The PhC structure has a square lattice of silicon rod with refractive index of 3.39 in air. The overall design and the results are discussed through the realization and the numerically simulation to confirm its operation and feasibility.

  15. Active optical zoom system

    DOEpatents

    Wick, David V.

    2005-12-20

    An active optical zoom system changes the magnification (or effective focal length) of an optical imaging system by utilizing two or more active optics in a conventional optical system. The system can create relatively large changes in system magnification with very small changes in the focal lengths of individual active elements by leveraging the optical power of the conventional optical elements (e.g., passive lenses and mirrors) surrounding the active optics. The active optics serve primarily as variable focal-length lenses or mirrors, although adding other aberrations enables increased utility. The active optics can either be LC SLMs, used in a transmissive optical zoom system, or DMs, used in a reflective optical zoom system. By appropriately designing the optical system, the variable focal-length lenses or mirrors can provide the flexibility necessary to change the overall system focal length (i.e., effective focal length), and therefore magnification, that is normally accomplished with mechanical motion in conventional zoom lenses. The active optics can provide additional flexibility by allowing magnification to occur anywhere within the FOV of the system, not just on-axis as in a conventional system.

  16. Long Term Optical and Infrared Reverberation Mapping of High and Low Luminosity Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Gorjian, Varoujan; Barth, Aaron; Brandt, Niel; Dawson, Kyle; Green, Paul; Ho, Luis; Horne, Keith; Jiang, Linhua; Joner, Mike; Kenney, John; McGreer, Ian; Nordgren, Tyler; Schneider, Donald; Shen, Yue; Tao, Charling

    2016-08-01

    Previous Spitzer reverberation monitoring projects looking for UV/optical light absorbed and re-emitted in the IR by dust have been limited to very low luminosity active galactic nuclei (AGN) that could potentially show reverberation within a single cycle (~1 year). Cycle 11-12's two year baseline allowed for the reverberation mapping of 17 high luminosity quasars from the Sloan Digital Sky Survey Reverberation Mapping project. By combining ground based monitoring from Pan-STARRS, CFHT, and Steward Observatory telescopes with Spitzer data we have for the first time detected dust reverberation in quasars. We propose to continue this project to capitalize on the continuing optical motnoring from the ground and to increase the confidence in the detected lags. Additionally, the Call for Proposals asks for up to 1000 hours of observations in the Spitzer CVZ to accommodate battery charging needs. We propose to add to our quasar sample five lower luminosity Seyfert galaxies from the Pan-STARRS ground based optical survey that are in the Spitzer CVZ, which will increase the luminosity range of AGN we are studying and, combined with additional ground based observatories, provide for a continuous monitoring campaign lasting 2 years and thus provide the most detailed study of dust around AGN to date.

  17. High-speed linear optics quantum computing using active feed-forward.

    PubMed

    Prevedel, Robert; Walther, Philip; Tiefenbacher, Felix; Böhi, Pascal; Kaltenbaek, Rainer; Jennewein, Thomas; Zeilinger, Anton

    2007-01-01

    As information carriers in quantum computing, photonic qubits have the advantage of undergoing negligible decoherence. However, the absence of any significant photon-photon interaction is problematic for the realization of non-trivial two-qubit gates. One solution is to introduce an effective nonlinearity by measurements resulting in probabilistic gate operations. In one-way quantum computation, the random quantum measurement error can be overcome by applying a feed-forward technique, such that the future measurement basis depends on earlier measurement results. This technique is crucial for achieving deterministic quantum computation once a cluster state (the highly entangled multiparticle state on which one-way quantum computation is based) is prepared. Here we realize a concatenated scheme of measurement and active feed-forward in a one-way quantum computing experiment. We demonstrate that, for a perfect cluster state and no photon loss, our quantum computation scheme would operate with good fidelity and that our feed-forward components function with very high speed and low error for detected photons. With present technology, the individual computational step (in our case the individual feed-forward cycle) can be operated in less than 150 ns using electro-optical modulators. This is an important result for the future development of one-way quantum computers, whose large-scale implementation will depend on advances in the production and detection of the required highly entangled cluster states.

  18. Optical recording of neuronal spiking activity from unbiased populations of neurons with high spike detection efficiency and high temporal precision.

    PubMed

    Ranganathan, Gayathri N; Koester, Helmut J

    2010-09-01

    Activity in populations of neurons is essential for cortical function including signaling of information and signal transport. Previous methods have made advances in recording activity from many neurons but have both technical and analytical limitations. Here we present an optical method, dithered random-access functional calcium imaging, to record somatic calcium signals from up to 100 neurons, in vitro and in vivo. We further developed a maximum-likelihood deconvolution algorithm to detect spikes and precise spike timings from the recorded calcium fluorescence signals. Spike detection efficiency and spike timing detection was determined in acute slices of juvenile mice. The results indicate that the combination of the two methods detected precise spiking activity from unbiased and spatially distributed populations of neurons in acute slices with high efficiency of spike detection (>97%), low rate of false positives (0.0023 spikes/s), and high temporal precision. The results further indicate that there is only a small window of excitation intensities where high spike detection can be achieved consistently.

  19. A High-Performance Deformable Mirror with Integrated Driver ASIC for Space Based Active Optics

    NASA Astrophysics Data System (ADS)

    Shelton, Chris

    Direct imaging of exoplanets is key to fully understanding these systems through spectroscopy and astrometry. The primary impediment to direct imaging of exoplanets is the extremely high brightness ratio between the planet and its parent star. Direct imaging requires a technique for contrast suppression, which include coronagraphs, and nulling interferometers. Deformable mirrors (DMs) are essential to both of these techniques. With space missions in mind, Microscale is developing a novel DM with direct integration of DM and its electronic control functions in a single small envelope. The Application Specific Integrated Circuit (ASIC) is key to the shrinking of the electronic control functions to a size compatible with direct integration with the DM. Through a NASA SBIR project, Microscale, with JPL oversight, has successfully demonstrated a unique deformable mirror (DM) driver ASIC prototype based on an ultra-low power switch architecture. Microscale calls this the Switch-Mode ASIC, or SM-ASIC, and has characterized it for a key set of performance parameters, and has tested its operation with a variety of actuator loads, such as piezo stack and unimorph, and over a wide temperature range. These tests show the SM-ASIC's capability of supporting active optics in correcting aberrations of a telescope in space. Microscale has also developed DMs to go with the SM-ASIC driver. The latest DM version produced uses small piezo stack elements in an 8x8 array, bonded to a novel silicon facesheet structure fabricated monolithically into a polished mirror on one side and mechanical linkage posts that connect to the piezoelectric stack actuators on the other. In this Supporting Technology proposal we propose to further develop the ASIC-DM and have assembled a very capable team to do so. It will be led by JPL, which has considerable expertise with DMs used in Adaptive Optics systems, with high-contrast imaging systems for exoplanet missions, and with designing DM driver

  20. Doped Contacts for High-Longevity Optically Activated, High Gain GaAs Photoconductive Semiconductor Switches

    SciTech Connect

    MAR,ALAN; LOUBRIEL,GUILLERMO M.; ZUTAVERN,FRED J.; O'MALLEY,MARTIN W.; HELGESON,WESLEY D.; BROWN,DARWIN JAMES; HJALMARSON,HAROLD P.; BACA,ALBERT G.; THORNTON,R.L.; DONALDSON,R.D.

    1999-12-17

    The longevity of high gain GaAs photoconductive semiconductor switches (PCSS) has been extended to over 100 million pulses. This was achieved by improving the ohmic contacts through the incorporation of a doped layer that is very effective in the suppression of filament formation, alleviating current crowding. Damage-free operation is now possible with virtually infinite expected lifetime at much higher current levels than before. The inherent damage-free current capacity of the bulk GaAs itself depends on the thickness of the doped layers and is at least 100A for a dopant diffusion depth of 4pm. The contact metal has a different damage mechanism and the threshold for damage ({approx}40A) is not further improved beyond a dopant diffusion depth of about 2{micro}m. In a diffusion-doped contact switch, the switching performance is not degraded when contact metal erosion occurs, unlike a switch with conventional contacts. This paper will compare thermal diffusion and epitaxial growth as approaches to doping the contacts. These techniques will be contrasted in terms of the fabrication issues and device characteristics.

  1. Doped Contacts for High-Longevity Optically Activated, High Gain GaAs Photoconductive Semiconductor Switches

    SciTech Connect

    Baca, A.G.; Brown, D.J.; Donaldson, R.D.; Helgeson, W.D.; Hjalmarson, H.P.; Loubriel, G.M.; Mar, A.; O'Malley, M.W.; Thornton, R.L.; Zutavern, F.J.

    1999-08-05

    The longevity of high gain GaAs photoconductive semiconductor switches (PCSS) has been extended to over 50 million pulses. This was achieved by improving the ohmic contacts through the incorporation of a doped layer beneath the PCSS contacts which is very effective in the suppression of filament formation and alleviating current crowding to improve the longevity of PCSS. Virtually indefinite, damage-free operation is now possible at much higher current levels than before. The inherent damage-free current capacity of the switch depends on the thickness of the doped layers and is at least 100A for a dopant diffusion depth of 4pm. The contact metal has a different damage mechanism and the threshold for damage ({approximately}40A) is not further improved beyond a dopant diffusion depth of about 2{micro}m. In a diffusion-doped contact switch, the switching performance is not degraded when contact metal erosion occurs. This paper will compare thermal diffusion and epitaxial growth as approaches to doping the contacts. These techniques will be contrasted in terms of the fabrication issues and device characteristics.

  2. Sunglint effects on the characterization of optically active substances in high spatial resolution airborne hyperspectral images

    NASA Astrophysics Data System (ADS)

    Streher, A. S.; Faria Barbosa, C. Clemente; Soares Galvão, L.; Goodman, J. A.; Silva, T. S.

    2013-05-01

    Sunglint, also known as the specular reflection of light from water surfaces, is a component of sensor-received radiance that represents a confounding factor on the characterization of water bodies by remote sensing. In airborne remote sensing images, the effect of sunglint can be minimized by optimizing the flight paths, directing the sensor towards or away from the Sun, and by keeping solar zenith angles between 30° and 60°. However, these guidelines cannot always be applied, often due to the irregular spatial pattern of lakes, estuaries and coastlines. The present study assessed the impact of sunglint on the relationship between the optically active substances (OAS) concentration, in optically complex waters, and the spectral information provided by an airborne high spatial resolution hyperspectral sensor (SpecTIR). The Ibitinga reservoir, located in southeastern Brazil (state of São Paulo), was selected as the study area because of its meandering shape. As a result, there is demanding constant changes in data acquisition geometry to achieve complete coverage, therefore not allowing sunglint conditions to be minimized during image acquisition. Field data collection was carried out on October 23 and 24, 2011. During these two days, 15 water stations along the reservoir were sampled, concurrently with the SpecTIR image acquisition in 357 bands (398-2455 nm) and at 3 m spatial resolution. Chlorophyll, pheophytin, total suspended solids, organic and inorganic suspended solids and colored dissolved matter were determined in laboratory. The images were corrected for the atmospheric effects using the Fast Line-of-sight Atmospheric Analysis of Spectral Hypercubes (FLAASH) algorithm and then geometrically corrected. In order to evaluate the sunglint effects on the OAS characterization, the images were corrected for such effects using the deglint algorithm from Goodman et al. (2008). The SpecTIR 662-nm band reflectance was selected to be correlated to the OAS due to

  3. Anisotropic Nanoantenna-Based Magnetoplasmonic Crystals for Highly Enhanced and Tunable Magneto-Optical Activity.

    PubMed

    Maccaferri, Nicolò; Bergamini, Luca; Pancaldi, Matteo; Schmidt, Mikolaj K; Kataja, Mikko; Dijken, Sebastiaan van; Zabala, Nerea; Aizpurua, Javier; Vavassori, Paolo

    2016-04-13

    We present a novel concept of a magnetically tunable plasmonic crystal based on the excitation of Fano lattice surface modes in periodic arrays of magnetic and optically anisotropic nanoantennas. We show how coherent diffractive far-field coupling between elliptical nickel nanoantennas is governed by the two in-plane, orthogonal and spectrally detuned plasmonic responses of the individual building block, one directly induced by the incident radiation and the other induced by the application of an external magnetic field. The consequent excitation of magnetic field-induced Fano lattice surface modes leads to highly tunable and amplified magneto-optical effects as compared to a continuous film or metasurfaces made of disordered noninteracting magnetoplasmonic anisotropic nanoantennas. The concepts presented here can be exploited to design novel magnetoplasmonic sensors based on coupled localized plasmonic resonances, and nanoscale metamaterials for precise control and magnetically driven tunability of light polarization states.

  4. Anisotropic Nanoantenna-Based Magnetoplasmonic Crystals for Highly Enhanced and Tunable Magneto-Optical Activity.

    PubMed

    Maccaferri, Nicolò; Bergamini, Luca; Pancaldi, Matteo; Schmidt, Mikolaj K; Kataja, Mikko; Dijken, Sebastiaan van; Zabala, Nerea; Aizpurua, Javier; Vavassori, Paolo

    2016-04-13

    We present a novel concept of a magnetically tunable plasmonic crystal based on the excitation of Fano lattice surface modes in periodic arrays of magnetic and optically anisotropic nanoantennas. We show how coherent diffractive far-field coupling between elliptical nickel nanoantennas is governed by the two in-plane, orthogonal and spectrally detuned plasmonic responses of the individual building block, one directly induced by the incident radiation and the other induced by the application of an external magnetic field. The consequent excitation of magnetic field-induced Fano lattice surface modes leads to highly tunable and amplified magneto-optical effects as compared to a continuous film or metasurfaces made of disordered noninteracting magnetoplasmonic anisotropic nanoantennas. The concepts presented here can be exploited to design novel magnetoplasmonic sensors based on coupled localized plasmonic resonances, and nanoscale metamaterials for precise control and magnetically driven tunability of light polarization states. PMID:26967047

  5. High speed optical networks

    NASA Astrophysics Data System (ADS)

    Frankel, Michael Y.; Livas, Jeff

    2005-02-01

    This overview will discuss core network technology and cost trade-offs inherent in choosing between "analog" architectures with high optical transparency, and ones heavily dependent on frequent "digital" signal regeneration. The exact balance will be related to the specific technology choices in each area outlined above, as well as the network needs such as node geographic spread, physical connectivity patterns, and demand loading. Over the course of a decade, optical networks have evolved from simple single-channel SONET regenerator-based links to multi-span multi-channel optically amplified ultra-long haul systems, fueled by high demand for bandwidth at reduced cost. In general, the cost of a well-designed high capacity system is dominated by the number of optical to electrical (OE) and electrical to optical (EO) conversions required. As the reach and channel capacity of the transport systems continued to increase, it became necessary to improve the granularity of the demand connections by introducing (optical add/drop multiplexers) OADMs. Thus, if a node requires only small demand connectivity, most of the optical channels are expressed through without regeneration (OEO). The network costs are correspondingly reduced, partially balanced by the increased cost of the OADM nodes. Lately, the industry has been aggressively pursuing a natural extension of this philosophy towards all-optical "analog" core networks, with each demand touching electrical digital circuitry only at the in/egress nodes. This is expected to produce a substantial elimination of OEO costs, increase in network capacity, and a notionally simpler operation and service turn-up. At the same time, such optical "analog" network requires a large amount of complicated hardware and software for monitoring and manipulating high bit rate optical signals. New and more complex modulation formats that provide resiliency to both optical noise and nonlinear propagation effects are important for extended

  6. Stochastic optical active rheology

    NASA Astrophysics Data System (ADS)

    Lee, Hyungsuk; Shin, Yongdae; Kim, Sun Taek; Reinherz, Ellis L.; Lang, Matthew J.

    2012-07-01

    We demonstrate a stochastic based method for performing active rheology using optical tweezers. By monitoring the displacement of an embedded particle in response to stochastic optical forces, a rapid estimate of the frequency dependent shear moduli of a sample is achieved in the range of 10-1-103 Hz. We utilize the method to probe linear viscoelastic properties of hydrogels at varied cross-linker concentrations. Combined with fluorescence imaging, our method demonstrates non-linear changes of bond strength between T cell receptors and an antigenic peptide due to force-induced cell activation.

  7. Optical activity and evolution.

    PubMed

    Khasanov, M M; Gladyshev, G P

    1980-09-01

    It is noted that the chemical reactions occurring in rarefied cosmic clouds (molecular concentration less than or approximately to 10(2) cm-3) differ from similar laboratory reactions by the much greater effect on the outcome of external force fields. In this light it is hypothesized that the synthesis of optically active substances may occur in the outer space under the conjoint stereospecific effect of a magnetic and other molecule-orienting field. It is further conjectured that the optically active substances of the Solar System had been produced in the course of its formation out of the primal rarefield cloud.

  8. High magneto-optical activity and low optical losses in metal-dielectric Au/Co/Au-SiO(2) magnetoplasmonic nanodisks.

    PubMed

    Banthí, Juan Carlos; Meneses-Rodríguez, David; García, Fernando; González, María Ujué; García-Martín, Antonio; Cebollada, Alfonso; Armelles, Gaspar

    2012-03-01

    Metal-dielectric Au-Co-SiO(2) magnetoplasmonic nanodisks are found to exhibit large magneto-optical activity and low optical losses. The internal architecture of the nanodisks is such that, in resonant conditions, the electromagnetic field undertakes a particular spatial distribution. This makes it possible to maximize the electromagnetic field at the magneto-optically active layers and minimize it in the other, optically lossy ones.

  9. Optical/UV, High Energy Gamma-ray activity from the FSRQ PKS 1502+106

    NASA Astrophysics Data System (ADS)

    Pacciani, Luigi

    2015-07-01

    We asked a Swift ToO campaign on the FSRQ PKS 1502+106 (z=1.83853), triggered by prolonged High Energy activity detected with FERMI-LAT. The HE trigger detected activity at E > 10 GeV with TS ~153, from 2015-06-17 to 2015-07-10, following the prescription of Pacciani et al.

  10. Highly selective anti-Prelog synthesis of optically active aryl alcohols by recombinant Escherichia coli expressing stereospecific alcohol dehydrogenase.

    PubMed

    Li, Ming; Nie, Yao; Mu, Xiao Qing; Zhang, Rongzhen; Xu, Yan

    2016-07-01

    Biocatalytic asymmetric synthesis has been widely used for preparation of optically active chiral alcohols as the important intermediates and precursors of active pharmaceutical ingredients. However, the available whole-cell system involving anti-Prelog specific alcohol dehydrogenase is yet limited. A recombinant Escherichia coli system expressing anti-Prelog stereospecific alcohol dehydrogenase from Candida parapsilosis was established as a whole-cell system for catalyzing asymmetric reduction of aryl ketones to anti-Prelog configured alcohols. Using 2-hydroxyacetophenone as the substrate, reaction factors including pH, cell status, and substrate concentration had obvious impacts on the outcome of whole-cell biocatalysis, and xylose was found to be an available auxiliary substrate for intracellular cofactor regeneration, by which (S)-1-phenyl-1,2-ethanediol was achieved with an optical purity of 97%e.e. and yield of 89% under the substrate concentration of 5 g/L. Additionally, the feasibility of the recombinant cells toward different aryl ketones was investigated, and most of the corresponding chiral alcohol products were obtained with an optical purity over 95%e.e. Therefore, the whole-cell system involving recombinant stereospecific alcohol dehydrogenase was constructed as an efficient biocatalyst for highly enantioselective anti-Prelog synthesis of optically active aryl alcohols and would be promising in the pharmaceutical industry.

  11. Optical design and active optics methods in astronomy

    NASA Astrophysics Data System (ADS)

    Lemaitre, Gerard R.

    2013-03-01

    Optical designs for astronomy involve implementation of active optics and adaptive optics from X-ray to the infrared. Developments and results of active optics methods for telescopes, spectrographs and coronagraph planet finders are presented. The high accuracy and remarkable smoothness of surfaces generated by active optics methods also allow elaborating new optical design types with high aspheric and/or non-axisymmetric surfaces. Depending on the goal and performance requested for a deformable optical surface analytical investigations are carried out with one of the various facets of elasticity theory: small deformation thin plate theory, large deformation thin plate theory, shallow spherical shell theory, weakly conical shell theory. The resulting thickness distribution and associated bending force boundaries can be refined further with finite element analysis.

  12. Investigation of solar active regions at high resolution by balloon flights of the solar optical universal polarimeter, definition phase

    NASA Technical Reports Server (NTRS)

    Tarbell, Theodore D.; Topka, Kenneth P.

    1992-01-01

    The definition phase of a scientific study of active regions on the sun by balloon flight of a former Spacelab instrument, the Solar Optical Universal Polarimeter (SOUP) is described. SOUP is an optical telescope with image stabilization, tunable filter and various cameras. After the flight phase of the program was cancelled due to budgetary problems, scientific and engineering studies relevant to future balloon experiments of this type were completed. High resolution observations of the sun were obtained using SOUP components at the Swedish Solar Observatory in the Canary Islands. These were analyzed and published in studies of solar magnetic fields and active regions. In addition, testing of low-voltage piezoelectric transducers was performed, which showed they were appropriate for use in image stabilization on a balloon.

  13. Ultra-high throughput detection of single cell β-galactosidase activity in droplets using micro-optical lens array

    NASA Astrophysics Data System (ADS)

    Lim, Jiseok; Vrignon, Jérémy; Gruner, Philipp; Karamitros, Christos S.; Konrad, Manfred; Baret, Jean-Christophe

    2013-11-01

    We demonstrate the use of a hybrid microfluidic-micro-optical system for the screening of enzymatic activity at the single cell level. Escherichia coli β-galactosidase activity is revealed by a fluorogenic assay in 100 pl droplets. Individual droplets containing cells are screened by measuring their fluorescence signal using a high-speed camera. The measurement is parallelized over 100 channels equipped with microlenses and analyzed by image processing. A reinjection rate of 1 ml of emulsion per minute was reached corresponding to more than 105 droplets per second, an analytical throughput larger than those obtained using flow cytometry.

  14. High Resolution Active Optics Observations from the Kepler Follow-up Observation Program

    NASA Astrophysics Data System (ADS)

    Gautier, Thomas N.; Ciardi, D. R.; Marcy, G. W.; Hirsch, L.

    2014-01-01

    The ground based follow-up observation program for candidate exoplanets discovered with the Kepler observatory has supported a major effort for high resolution imaging of candidate host stars using adaptive optics wave-front correction (AO), speckle imaging and lucky imaging. These images allow examination of the sky as close as a few tenths of an arcsecond from the host stars to detect background objects that might be the source of the Kepler transit signal instead of the host star. This poster reports on the imaging done with AO cameras on the Keck, Palomar 5m and Shane 3m (Lick Observatory) which have been used to obtain high resolution images of over 500 Kepler Object of Interest (KOI) exoplanet candidate host stars. All observations were made at near infrared wavelengths in the J, H and K bands, mostly using the host target star as the AO guide star. Details of the sensitivity to background objects actually attained by these observations and the number of background objects discovered are presented. Implications to the false positive rate of the Kepler candidates are discussed.

  15. High-resolution non-contact measurement of the electrical activity of plants in situ using optical recording

    PubMed Central

    Zhao, Dong-Jie; Chen, Yang; Wang, Zi-Yang; Xue, Lin; Mao, Tong-Lin; Liu, Yi-Min; Wang, Zhong-Yi; Huang, Lan

    2015-01-01

    The limitations of conventional extracellular recording and intracellular recording make high-resolution multisite recording of plant bioelectrical activity in situ challenging. By combining a cooled charge-coupled device camera with a voltage-sensitive dye, we recorded the action potentials in the stem of Helianthus annuus and variation potentials at multiple sites simultaneously with high spatial resolution. The method of signal processing using coherence analysis was used to determine the synchronization of the selected signals. Our results provide direct visualization of the phloem, which is the distribution region of the electrical activities in the stem and leaf of H. annuus, and verify that the phloem is the main action potential transmission route in the stems of higher plants. Finally, the method of optical recording offers a unique opportunity to map the dynamic bioelectrical activity and provides an insight into the mechanisms of long-distance electrical signal transmission in higher plants. PMID:26333536

  16. High-resolution wind speed measurements using actively heated fiber optics

    NASA Astrophysics Data System (ADS)

    Sayde, Chadi; Thomas, Christoph K.; Wagner, James; Selker, John

    2015-11-01

    We present a novel technique to simultaneously measure wind speed (U) at thousands of locations continuously in time based on measurement of velocity-dependent heat transfer from a heated surface. Measuring temperature differences between paired passive and actively heated fiber-optic (AHFO) cables with a distributed temperature sensing system allowed estimation of U at over 2000 sections along the 230 m transect (resolution of 0.375 m and 5.5 s). The underlying concept is similar to that of a hot wire anemometer extended in space. The correlation coefficient between U measured by two colocated sonic anemometers and the AHFO were 0.91 during the day and 0.87 at night. The combination of classical passive and novel AHFO provides unprecedented dynamic observations of both air temperature and wind speed spanning 4 orders of magnitude in spatial scale (0.1-1000 m) while resolving individual turbulent motions, opening new opportunities for testing basic theories for near-surface geophysical flows.

  17. High throughput optical scanner

    DOEpatents

    Basiji, David A.; van den Engh, Gerrit J.

    2001-01-01

    A scanning apparatus is provided to obtain automated, rapid and sensitive scanning of substrate fluorescence, optical density or phosphorescence. The scanner uses a constant path length optical train, which enables the combination of a moving beam for high speed scanning with phase-sensitive detection for noise reduction, comprising a light source, a scanning mirror to receive light from the light source and sweep it across a steering mirror, a steering mirror to receive light from the scanning mirror and reflect it to the substrate, whereby it is swept across the substrate along a scan arc, and a photodetector to receive emitted or scattered light from the substrate, wherein the optical path length from the light source to the photodetector is substantially constant throughout the sweep across the substrate. The optical train can further include a waveguide or mirror to collect emitted or scattered light from the substrate and direct it to the photodetector. For phase-sensitive detection the light source is intensity modulated and the detector is connected to phase-sensitive detection electronics. A scanner using a substrate translator is also provided. For two dimensional imaging the substrate is translated in one dimension while the scanning mirror scans the beam in a second dimension. For a high throughput scanner, stacks of substrates are loaded onto a conveyor belt from a tray feeder.

  18. Ultra-high Speed Optical Imaging of Ultrasound-activated Microbubbles in Mesenteric Microvessels

    NASA Astrophysics Data System (ADS)

    Chen, Hong

    Ultrasound contrast agent microbubbles have gained widespread applications in diagnostic and therapeutic ultrasound. Animal studies of bioeffects induced by ultrasound-activated microbubbles have demonstrated that microbubbles can cause microvessel damage. Much scientific attention has been attracted to such microvascular bioeffects, not only because of the related safety concerns, but also because of the potential useful applications of microbubbles in the intravascular delivery of drugs and genetic materials into target tissues. A significant challenge in using microbubbles in medical ultrasound is the lack of knowledge about how the microbubbles behave in blood vessels when exposed to ultrasound and how their interactions with ultrasound cause vascular damage. Although extensive studies were performed in the past to study the dynamics of microbubbles, most of those studies were performed in vitro and did not directly address the clinical environment in which microbubbles are injected into blood vessels. In this thesis work, a synchronized optical-acoustic system was set up for ultrahigh speed imaging of insonated microbubbles in microvessels. The recorded images revealed the formation of microjets penetrating the microbubbles, as well as vessel distention (motion outward against the surrounding tissue) and vessel invagination (motion inward toward the lumen) caused by the expansion and collapse of the microbubbles, respectively. Contrary to current paradigms which propose that microbubbles damage vessels either by distending them or by forming liquid jets impinging on them, microbubbles translation and jetting were in the direction away from the nearest vessel wall; furthermore, invagination typically exceeded distention in arterioles and venules. Vessel invagination was found to be associated with vascular damage. These studies suggest that vessel invagination may be a newly discovered potential mechanism for vascular damage by ultrasound-activated microbubbles

  19. Low-noise and high-gain Brillouin optical amplifier for narrowband active optical filtering based on a pump-to-signal optoelectronic tracking.

    PubMed

    Souidi, Yahia; Taleb, Fethallah; Zheng, Junbo; Lee, Min Won; Du Burck, Frédéric; Roncin, Vincent

    2016-01-10

    We implement and characterize an optical narrowband amplifier based on stimulated Brillouin scattering with pump-to-signal relative frequency fluctuations overcome thanks to an active pump tracking. We achieve a precise characterization of this amplifier in terms of gain and noise degradation (noise figure). The performances of this stable selective amplification are compared to those of a conventional erbium-doped fiber amplifier in order to highlight the interest of the Brillouin amplification solution for active narrow optical filtering with a bandpass of 10 MHz. Thanks to the simple optoelectronic pump-to-signal tracking, the Brillouin active filter appears as a stable and reliable solution for narrowband optical processing in the coherent optical communication context and optical sensor applications. PMID:26835759

  20. Parallel Optical Control of Spatiotemporal Neuronal Spike Activity Using High-Speed Digital Light Processing

    PubMed Central

    Jerome, Jason; Foehring, Robert C.; Armstrong, William E.; Spain, William J.; Heck, Detlef H.

    2011-01-01

    Neurons in the mammalian neocortex receive inputs from and communicate back to thousands of other neurons, creating complex spatiotemporal activity patterns. The experimental investigation of these parallel dynamic interactions has been limited due to the technical challenges of monitoring or manipulating neuronal activity at that level of complexity. Here we describe a new massively parallel photostimulation system that can be used to control action potential firing in in vitro brain slices with high spatial and temporal resolution while performing extracellular or intracellular electrophysiological measurements. The system uses digital light processing technology to generate 2-dimensional (2D) stimulus patterns with >780,000 independently controlled photostimulation sites that operate at high spatial (5.4 μm) and temporal (>13 kHz) resolution. Light is projected through the quartz–glass bottom of the perfusion chamber providing access to a large area (2.76 mm × 2.07 mm) of the slice preparation. This system has the unique capability to induce temporally precise action potential firing in large groups of neurons distributed over a wide area covering several cortical columns. Parallel photostimulation opens up new opportunities for the in vitro experimental investigation of spatiotemporal neuronal interactions at a broad range of anatomical scales. PMID:21904526

  1. Nondispersive optical activity of meshed helical metamaterials.

    PubMed

    Park, Hyun Sung; Kim, Teun-Teun; Kim, Hyeon-Don; Kim, Kyungjin; Min, Bumki

    2014-11-17

    Extreme optical properties can be realized by the strong resonant response of metamaterials consisting of subwavelength-scale metallic resonators. However, highly dispersive optical properties resulting from strong resonances have impeded the broadband operation required for frequency-independent optical components or devices. Here we demonstrate that strong, flat broadband optical activity with high transparency can be obtained with meshed helical metamaterials in which metallic helical structures are networked and arranged to have fourfold rotational symmetry around the propagation axis. This nondispersive optical activity originates from the Drude-like response as well as the fourfold rotational symmetry of the meshed helical metamaterials. The theoretical concept is validated in a microwave experiment in which flat broadband optical activity with a designed magnitude of 45° per layer of metamaterial is measured. The broadband capabilities of chiral metamaterials may provide opportunities in the design of various broadband optical systems and applications.

  2. Optical control of antibacterial activity

    NASA Astrophysics Data System (ADS)

    Velema, Willem A.; van der Berg, Jan Pieter; Hansen, Mickel J.; Szymanski, Wiktor; Driessen, Arnold J. M.; Feringa, Ben L.

    2013-11-01

    Bacterial resistance is a major problem in the modern world, stemming in part from the build-up of antibiotics in the environment. Novel molecular approaches that enable an externally triggered increase in antibiotic activity with high spatiotemporal resolution and auto-inactivation are highly desirable. Here we report a responsive, broad-spectrum, antibacterial agent that can be temporally activated with light, whereupon it auto-inactivates on the scale of hours. The use of such a ‘smart’ antibiotic might prevent the build-up of active antimicrobial material in the environment. Reversible optical control over active drug concentration enables us to obtain pharmacodynamic information. Precisely localized control of activity is achieved, allowing the growth of bacteria to be confined to defined patterns, which has potential for the development of treatments that avoid interference with the endogenous microbial population in other parts of the organism.

  3. Investigation of solar active regions at high resolution by balloon flights of the solar optical universal polarimeter, extended definition phase

    NASA Technical Reports Server (NTRS)

    Tarbell, Theodore D.

    1993-01-01

    Technical studies of the feasibility of balloon flights of the former Spacelab instrument, the Solar Optical Universal Polarimeter, with a modern charge-coupled device (CCD) camera, to study the structure and evolution of solar active regions at high resolution, are reviewed. In particular, different CCD cameras were used at ground-based solar observatories with the SOUP filter, to evaluate their performance and collect high resolution images. High resolution movies of the photosphere and chromosphere were successfully obtained using four different CCD cameras. Some of this data was collected in coordinated observations with the Yohkoh satellite during May-July, 1992, and they are being analyzed scientifically along with simultaneous X-ray observations.

  4. Optical Studies of Active Comets

    NASA Technical Reports Server (NTRS)

    Jewitt, David

    1998-01-01

    This grant was to support optical studies of comets close enough to the sun to be outgassing. The main focus of the observations was drawn to the two extraordinarily bright comets Hyakutake and Hale-Bopp, but other active comets were also studied in detail during the period of funding. Major findings (all fully published) under this grant include: (1) Combined optical and submillimeter observations of the comet/Centaur P/Schwassmann-Wachmann 1 were used to study the nature of mass loss from this object. The submillimeter observations show directly that the optically prominent dust coma is ejected by the sublimation of carbon monoxide. Simultaneous optical-submillimeter observations allowed us to test earlier determinations of the dust mass loss rate. (2) We modelled the rotation of cometary nuclei using time-resolved images of dust jets as the primary constraint. (3) We obtained broad-band optical images of several comets for which we subsequently attempted submillimeter observations, in order to test and update the cometary ephemerides. (4) Broad-band continuum images of a set of weakly active comets and, apparently, inactive asteroids were obtained in BVRI using the University of Hawaii 2.2-m telescope. These images were taken in support of a program to test the paradigm that many near-Earth asteroids might be dead or dormant comets. We measured coma vs. nucleus colors in active comets (finding that coma particle scattering is different from, and cannot be simply related to, nucleus color). We obtained spectroscopic observations of weakly active comets and other small bodies using the HIRES spectrograph on the Keck 10-m telescope. These observation place sensitive limits to outgassing from these bodies, aided by the high (40,000) spectral resolution of HIRES.

  5. MAMBO observations at 240GHz of optically obscured Spitzer sources: source clumps and radio activity at high redshift

    NASA Astrophysics Data System (ADS)

    Andreani, P.; Magliocchetti, M.; de Zotti, G.

    2010-01-01

    Optically very faint (R > 25.5) sources detected by the Spitzer Space Telescope at 24μm represent a very interesting population at redshift z ~ (1.5-3). They exhibit strong clustering properties, implying that they are hosted by very massive haloes, and their mid-infrared emission could be powered by either dust-enshrouded star formation and/or by an obscured active galactic nucleus (AGN). We report observations carried out with the Max Planck Millimetre Bolometer (MAMBO) array at the IRAM 30-m antenna on Pico Veleta of a candidate protocluster with five optically obscured sources selected from the 24-μm Spitzer sample of the First-Look Survey. Interestingly, these sources appear to lie on a high-density filament aligned with the two radio jets of an AGN. Four out of five of the observed sources were detected. We combine these measurements with optical, infrared and radio observations to probe the nature of the candidate protocluster members. Our preliminary conclusions can be summarized as follows: the spectral energy distributions (SEDs) of all sources include both AGN and starburst contributions; the AGN contribution to the bolometric luminosities ranges between 14 and 26 per cent of the total. Such a contribution is enough for the AGN to dominate the emission at 5.8, 8 and 24μm, while the stellar component, inferred from SED fitting, prevails at 1.25mm and at λ < 4.5μm. The present analysis suggests a coherent interplay at high z between extended radio activity and the development of filamentary large-scale structures.

  6. High bandwidth optical mount

    DOEpatents

    Bender, D.A.; Kuklo, T.

    1994-11-08

    An optical mount, which directs a laser beam to a point by controlling the position of a light-transmitting optic, is stiffened so that a lowest resonant frequency of the mount is approximately one kilohertz. The optical mount, which is cylindrically-shaped, positions the optic by individually moving a plurality of carriages which are positioned longitudinally within a sidewall of the mount. The optical mount is stiffened by allowing each carriage, which is attached to the optic, to move only in a direction which is substantially parallel to a center axis of the optic. The carriage is limited to an axial movement by flexures or linear bearings which connect the carriage to the mount. The carriage is moved by a piezoelectric transducer. By limiting the carriage to axial movement, the optic can be kinematically clamped to a carriage. 5 figs.

  7. High bandwidth optical mount

    DOEpatents

    Bender, Donald A.; Kuklo, Thomas

    1994-01-01

    An optical mount, which directs a laser beam to a point by controlling the position of a light-transmitting optic, is stiffened so that a lowest resonant frequency of the mount is approximately one kilohertz. The optical mount, which is cylindrically-shaped, positions the optic by individually moving a plurality of carriages which are positioned longitudinally within a sidewall of the mount. The optical mount is stiffened by allowing each carriage, which is attached to the optic, to move only in a direction which is substantially parallel to a center axis of the optic. The carriage is limited to an axial movement by flexures or linear bearings which connect the carriage to the mount. The carriage is moved by a piezoelectric transducer. By limiting the carriage to axial movement, the optic can be kinematically clamped to a carriage.

  8. Highly efficient active optical interconnect incorporating a partially chlorinated ribbon POF in conjunction with a visible VCSEL.

    PubMed

    Lee, Hak-Soon; Lee, Sang-Shin; Kim, Bong-Seok; Son, Yung-Sung

    2014-05-19

    A low-loss 4-ch active optical interconnect (AOI) enabling passive alignment was proposed and built resorting to a transmitter (Tx) incorporating a red 680-nm VCSEL, which is linked to a receiver (Rx) module via a partially chlorinated ribbon POF. The POF was observed to exhibit an extremely low loss of ~0.24 dB/m at λ = 680 nm, in comparison to ~1.29 dB/m at λ = 850 nm, and a large numerical aperture of ~0.42. Both the Tx and Rx, which taps into a beam router based on collimated beam optics involving a pair of spherical lenses, were meant to be substantially alignment tolerant and compact. The achieved tolerance for the constructed modules was beyond 40 μm in terms of the positioning of VCSEL and photodetector. The proposed AOI was completed by linking the Tx with the Rx via a 3-m long ribbon POF, incurring a transmission loss of as small as 3.2 dB. The AOI was practically assessed in terms of a high-speed data transmission over a wide range of temperatures and then exploited to convey full HD video signals.

  9. High Availability in Optical Networks

    NASA Astrophysics Data System (ADS)

    Grover, Wayne D.; Wosinska, Lena; Fumagalli, Andrea

    2005-09-01

    Call for Papers: High Availability in Optical Networks Submission Deadline: 1 January 2006 The Journal of Optical Networking (JON) is soliciting papers for a feature Issue pertaining to all aspects of reliable components and systems for optical networks and concepts, techniques, and experience leading to high availability of services provided by optical networks. Most nations now recognize that telecommunications in all its forms -- including voice, Internet, video, and so on -- are "critical infrastructure" for the society, commerce, government, and education. Yet all these services and applications are almost completely dependent on optical networks for their realization. "Always on" or apparently unbreakable communications connectivity is the expectation from most users and for some services is the actual requirement as well. Achieving the desired level of availability of services, and doing so with some elegance and efficiency, is a meritorious goal for current researchers. This requires development and use of high-reliability components and subsystems, but also concepts for active reconfiguration and capacity planning leading to high availability of service through unseen fast-acting survivability mechanisms. The feature issue is also intended to reflect some of the most important current directions and objectives in optical networking research, which include the aspects of integrated design and operation of multilevel survivability and realization of multiple Quality-of-Protection service classes. Dynamic survivable service provisioning, or batch re-provisioning is an important current theme, as well as methods that achieve high availability at far less investment in spare capacity than required by brute force service path duplication or 100% redundant rings, which is still the surprisingly prevalent practice. Papers of several types are envisioned in the feature issue, including outlook and forecasting types of treatments, optimization and analysis, new

  10. High-Resolution fMRI Maps of Cortical Activation in Nonhuman Primates: Correlation with Intrinsic Signal Optical Images

    PubMed Central

    Roe, Anna W.; Chen, Li Min

    2009-01-01

    One of the most widely used functional brain mapping tools is blood oxygen level–dependent (BOLD) functional magnetic resonance imaging (fMRI). This method has contributed to new understandings of the functional roles of different areas in the human brain. However, its ability to map cerebral cortex at high spatial (submillimeter) resolution is still unknown. Other methods such as single- and multiunit electrophysiology and intrinsic signal optical imaging have revealed submillimeter resolution of sensory topography and cortical columnar activations. However, they are limited either by spatial scale (electrophysiology characterizes only local groups of neurons) or by the inability to monitor deep structures in the brain (i.e., cortical regions buried in sulci or subcortical structures). A method that could monitor all regions of the brain at high spatial resolution would be ideal. This capacity would open the doors to investigating, for example, how networks of cerebral cortical columns relate to or produce behavior. In this article we demonstrate that, without benefit of contrast agents, at a magnetic field strength of 9.4 tesla, BOLD fMRI can reveal millimeter-sized topographic maps of digit representation in the somatosensory cortex of the anesthetized squirrel monkey. Furthermore, by mapping the “funneling illusion,” it is possible to detect even submillimeter shifts in activation in the cortex. Our data suggest that at high magnetic field strength, the positive BOLD signal can be used to reveal high spatial resolution maps of brain activity, a finding that weakens previous notions about the ultimate spatial specificity of the positive BOLD signal. PMID:18172338

  11. A scintillating fiber-optic active target (SFT) for studies of high energy photoproduction

    SciTech Connect

    Ruchti, R.; Baumbaugh, B.; Bishop, J.; Busenitz, J.; Cason, N.; Cunningham, J.; Gardner, R.; Kennedy, C.; Mannel, E.; Mountain, R.J.

    1988-02-01

    A high resolution, gateable, Scintillating Fiber Target (SFT) has been developed for Fermilab Experiment E687 to study charm and beauty particle production and decay in high energy photon interactions. The detector consists of a scintillating target of either GS1 Cerium glass fibers or polystyrene fibers of 29..mu..m cross section, a multi-stage image intensifier and an intensified CCD or SIT/VIDICON camera system used in conjunction with a custom-built video data acquisition system.

  12. A scintillating fiber-optic active target (SFT) for studies of high energy photoproduction

    SciTech Connect

    Ruchti, R.; Baumbaugh, B.; Bishop, J.; Busenitz, J.; Cason, N.; Cunningham, J.; Gardner, R.; Kennedy, C.; Mannel, E.; Mountain, R.J.

    1987-10-01

    A high resolution, gateable, Scintillating Fiber Target (SFT) has been developed for Fermilab Experiment E687 to study charm and beauty particle production and decay in high energy photon interactions. The detector consists of a scintillating target of either GS1 Cerium glass fibers or polystyrene fibers of 29..mu..m cross section, a multi-stage image intensifier and an intensified CCD or SIT/VIDICON camera system used in conjunction with a custom-built video data acquisition system. 7 refs., 8 figs., 1 tab.

  13. Longevity improvement of optically activated, high gain GaAs photoconductive semiconductor switches

    SciTech Connect

    MAR,ALAN; LOUBRIEL,GUILLERMO M.; ZUTAVERN,FRED J.; O'MALLEY,MARTIN W.; HELGESON,WESLEY D.; BROWN,DARWIN JAMES; HJALMARSON,HAROLD P.; BACA,ALBERT G.

    2000-03-02

    The longevity of high gain GaAs photoconductive semiconductor switches (PCSS) has been extended to over 100 million pulses at 23A, and over 100 pulses at 1kA. This is achieved by improving the ohmic contacts by doping the semi-insulating GaAs underneath the metal, and by achieving a more uniform distribution of contact wear across the entire switch by distributing the trigger light to form multiple filaments. This paper will compare various approaches to doping the contacts, including ion implantation, thermal diffusion, and epitaxial growth. The device characterization also includes examination of the filament behavior using open-shutter, infra-red imaging during high gain switching. These techniques provide information on the filament carrier densities as well as the influence that the different contact structures and trigger light distributions have on the distribution of the current in the devices. This information is guiding the continuing refinement of contact structures and geometries for further improvements in switch longevity.

  14. Active Faraday optical frequency standard.

    PubMed

    Zhuang, Wei; Chen, Jingbiao

    2014-11-01

    We propose the mechanism of an active Faraday optical clock, and experimentally demonstrate an active Faraday optical frequency standard based on narrow bandwidth Faraday atomic filter by the method of velocity-selective optical pumping of cesium vapor. The center frequency of the active Faraday optical frequency standard is determined by the cesium 6 (2)S(1/2) F=4 to 6 (2)P(3/2) F'=4 and 5 crossover transition line. The optical heterodyne beat between two similar independent setups shows that the frequency linewidth reaches 281(23) Hz, which is 1.9×10(4) times smaller than the natural linewidth of the cesium 852-nm transition line. The maximum emitted light power reaches 75 μW. The active Faraday optical frequency standard reported here has advantages of narrow linewidth and reduced cavity pulling, which can readily be extended to other atomic transition lines of alkali and alkaline-earth metal atoms trapped in optical lattices at magic wavelengths, making it useful for new generation of optical atomic clocks. PMID:25361349

  15. Active Faraday optical frequency standard.

    PubMed

    Zhuang, Wei; Chen, Jingbiao

    2014-11-01

    We propose the mechanism of an active Faraday optical clock, and experimentally demonstrate an active Faraday optical frequency standard based on narrow bandwidth Faraday atomic filter by the method of velocity-selective optical pumping of cesium vapor. The center frequency of the active Faraday optical frequency standard is determined by the cesium 6 (2)S(1/2) F=4 to 6 (2)P(3/2) F'=4 and 5 crossover transition line. The optical heterodyne beat between two similar independent setups shows that the frequency linewidth reaches 281(23) Hz, which is 1.9×10(4) times smaller than the natural linewidth of the cesium 852-nm transition line. The maximum emitted light power reaches 75 μW. The active Faraday optical frequency standard reported here has advantages of narrow linewidth and reduced cavity pulling, which can readily be extended to other atomic transition lines of alkali and alkaline-earth metal atoms trapped in optical lattices at magic wavelengths, making it useful for new generation of optical atomic clocks.

  16. Optical high acidity sensor

    DOEpatents

    Jorgensen, B.S.; Nekimken, H.L.; Carey, W.P.; O`Rourke, P.E.

    1997-07-22

    An apparatus and method for determining acid concentrations in solutions having acid concentrations of from about 0.1 Molar to about 16 Molar is disclosed. The apparatus includes a chamber for interrogation of the sample solution, a fiber optic light source for passing light transversely through the chamber, a fiber optic collector for receiving the collimated light after transmission through the chamber, a coating of an acid resistant polymeric composition upon at least one fiber end or lens, the polymeric composition in contact with the sample solution within the chamber and having a detectable response to acid concentrations within the range of from about 0.1 Molar to about 16 Molar, a measurer for the response of the polymeric composition in contact with the sample solution, and a comparer of the measured response to predetermined standards whereby the acid molarity of the sample solution within the chamber can be determined. Preferably, a first lens is attached to the end of the fiber optic light source, the first lens adapted to collimate light from the fiber optic light source, and a second lens is attached to the end of the fiber optic collector for focusing the collimated light after transmission through the chamber. 10 figs.

  17. Optical high acidity sensor

    DOEpatents

    Jorgensen, Betty S.; Nekimken, Howard L.; Carey, W. Patrick; O'Rourke, Patrick E.

    1997-01-01

    An apparatus and method for determining acid concentrations in solutions having acid concentrations of from about 0.1 Molar to about 16 Molar is disclosed. The apparatus includes a chamber for interrogation of the sample solution, a fiber optic light source for passing light transversely through the chamber, a fiber optic collector for receiving the collimated light after transmission through the chamber, a coating of an acid resistant polymeric composition upon at least one fiber end or lens, the polymeric composition in contact with the sample solution within the chamber and having a detectable response to acid concentrations within the range of from about 0.1 Molar to about 16 Molar, a measurer for the response of the polymeric composition in contact with the sample solution, and, a comparer of the measured response to predetermined standards whereby the acid molarity of the sample solution within the chamber can be determined. Preferably, a first lens is attached to the end of the fiber optic light source, the first lens adapted to collimate light from the fiber optic light source, and a second lens is attached to the end of the fiber optic collector for focusing the collimated light after transmission through the chamber.

  18. Simultaneous production of l-lactic acid with high optical activity and a soil amendment with food waste that demonstrates plant growth promoting activity.

    PubMed

    Kitpreechavanich, Vichien; Hayami, Arisa; Talek, Anfal; Chin, Clament Fui Seung; Tashiro, Yukihiro; Sakai, Kenji

    2016-07-01

    A unique method to produce highly optically-active l-lactic acid and soil amendments that promote plant growth from food waste was proposed. Three Bacillus strains Bacillus subtilis KBKU21, B. subtilis N3-9 and Bacillus coagulans T27, were used. Strain KBKU21 accumulated 36.9 g/L l-lactic acid with 95.7% optical activity and 98.2% l-lactic acid selectivity when fermented at 43°C for 84 h in a model kitchen refuse (MKR) medium. Residual precipitate fraction (anaerobically-fermented MKR (AFM) compost) analysis revealed 4.60%, 0.70% and 0.75% of nitrogen (as N), phosphorous (as P2O5), and potassium (as K2O), respectively. Additionally, the carbon to nitrogen ratio decreased from 13.3 to 10.6. AFM compost with KBKU21 promoted plant growth parameters, including leaf length, plant height and fresh weight of Brassica rapa (Komatsuna), than that by chemical fertilizers or commercial compost. The concept provides an incentive for the complete recycling of food waste, contributing towards a sustainable production system.

  19. Simultaneous production of l-lactic acid with high optical activity and a soil amendment with food waste that demonstrates plant growth promoting activity.

    PubMed

    Kitpreechavanich, Vichien; Hayami, Arisa; Talek, Anfal; Chin, Clament Fui Seung; Tashiro, Yukihiro; Sakai, Kenji

    2016-07-01

    A unique method to produce highly optically-active l-lactic acid and soil amendments that promote plant growth from food waste was proposed. Three Bacillus strains Bacillus subtilis KBKU21, B. subtilis N3-9 and Bacillus coagulans T27, were used. Strain KBKU21 accumulated 36.9 g/L l-lactic acid with 95.7% optical activity and 98.2% l-lactic acid selectivity when fermented at 43°C for 84 h in a model kitchen refuse (MKR) medium. Residual precipitate fraction (anaerobically-fermented MKR (AFM) compost) analysis revealed 4.60%, 0.70% and 0.75% of nitrogen (as N), phosphorous (as P2O5), and potassium (as K2O), respectively. Additionally, the carbon to nitrogen ratio decreased from 13.3 to 10.6. AFM compost with KBKU21 promoted plant growth parameters, including leaf length, plant height and fresh weight of Brassica rapa (Komatsuna), than that by chemical fertilizers or commercial compost. The concept provides an incentive for the complete recycling of food waste, contributing towards a sustainable production system. PMID:26819060

  20. Active Optics for high contrast imaging:Super smooth off-axis parabolas for ELTs XAO instruments

    NASA Astrophysics Data System (ADS)

    Hugot, Emmanuel; Laslandes, Marie; Ferrari, Marc; Dohlen, Kjetil; El hadi, Kacem

    2011-09-01

    In the context of direct imaging of exoplanets using XAO, the main limitations in images are due to residual quasi-static speckles induced by atmospheric phase residuals and instrumental static and quasi-static aberrations not corrected by AO: the post-coronagraphic image quality is directly linked to the power spectral density (PSD) of the optical train before the coronagraph. In this context, the potential of Stress Polishing has been demonstrated at LAM after the delivery of the three toric mirrors (TMs) for the VLT-SPHERE instrument. The extreme optical quality of such aspherical optics is obtained thanks to the spherical polishing of warped mirrors using full sized tools, avoiding the generation of high spatial frequency ripples due to classical sub-aperture tool marks. Furthermore, sub-nanometric roughnesses have been obtained thanks to a super smoothing method. Work is ongoing at LAM in order to improve this manufacturing method to cover a wide range of off-axis aspherics, with a reduction of the manufacturing time and cost. Smart warping structures are designed in order to bend the mirrors with a combination of focus, astigmatism and coma. This development will allow the stress polishing of supersmooth OAP for XAO optical relays improving the wavefront quality and in this way the high contrast level of future exoplanet imagers.

  1. Gated high speed optical detector

    NASA Technical Reports Server (NTRS)

    Green, S. I.; Carson, L. M.; Neal, G. W.

    1973-01-01

    The design, fabrication, and test of two gated, high speed optical detectors for use in high speed digital laser communication links are discussed. The optical detectors used a dynamic crossed field photomultiplier and electronics including dc bias and RF drive circuits, automatic remote synchronization circuits, automatic gain control circuits, and threshold detection circuits. The equipment is used to detect binary encoded signals from a mode locked neodynium laser.

  2. Laser and optics activities at CREOL

    SciTech Connect

    Stickley, C.M.

    1995-06-01

    CREOL is an interdisciplinary institute with a mission to foster and support research and education in the optical and laser sciences and engineering. CREOL`s principal members are its 21-strong faculty. The faculty are encouraged and supported in developing, maintaining, and expanding innovative and sponsored research programs, especially ones that are coupled to industry`s needs. The CREOL Director and Assistant Director, through empowerment by the CREOL faculty, coordinate and oversee the interactive, interdisciplinary projects of the faculty, the 85 graduate students and the 39 research staff. CREOL integrates these research efforts with the general educational mission and goals of the university, develops comprehensive course work in the optical and laser sciences and engineering, provides guidance and instruction to graduate students, administers MS and PhD programs, and provides facilities, funds, and administrative support to assist the faculty in carrying out CREOL`s mission and obtaining financial support for the research projects. CREOL`s specific areas of research activity include the following: IR systems; nonlinear optics; crystal growth; nonlinear integrated optics; new solid-state lasers; tunable far-infrared lasers; thin-film optics; theory; semiconductor lasers; x-ray/optical scattering; laser-induced damage; free-electron lasers; solid-state spectroscopy; x-ray sources and applications; laser propagation; laser processing of materials; optical design; optical limiting/sensor protection; diffractive optics; quantum well optoelectronics; dense plasmas/high-field physics; laser radar and remote sensing; diode-based lasers; and glass science.

  3. Module greenhouse with high efficiency of transformation of solar energy, utilizing active and passive glass optical rasters

    SciTech Connect

    Korecko, J.; Jirka, V.; Sourek, B.; Cerveny, J.

    2010-10-15

    Since the eighties of the 20th century, various types of linear glass rasters for architectural usage have been developed in the Czech Republic made by the continuous melting technology. The development was focused on two main groups of rasters - active rasters with linear Fresnel lenses in fixed installation and with movable photo-thermal and/or photo-thermal/photo-voltaic absorbers. The second group are passive rasters based on total reflection of rays on an optical prism. During the last years we have been working on their standardization, exact measuring of their optical and thermal-technical characteristics and on creation of a final product that could be applied in solar architecture. With the project supported by the Ministry of Environment of the Czech Republic we were able to build an experimental greenhouse using these active and passive optical glass rasters. The project followed the growing number of technical objectives. The concept of the greenhouse consisted of interdependence construction - structural design of the greenhouse with its technological equipment securing the required temperature and humidity conditions in the interior of the greenhouse. This article aims to show the merits of the proposed scheme and presents the results of the mathematical model in the TRNSYS environment through which we could predict the future energy balance carried out similar works, thus optimizing the investment and operating costs. In this article description of various technology applications for passive and active utilization of solar radiation is presented, as well as some results of short-term and long-term experiments, including evaluation of 1-year operation of the greenhouse from the energy and interior temperature viewpoints. A comparison of the calculated energy flows in the greenhouse to real measured values, for verification of the installed model is also involved. (author)

  4. Optical activity of BL Lacertae

    NASA Astrophysics Data System (ADS)

    Larionov, V.; Blinov, D.; Konstantinova, T.

    2012-04-01

    We perform optical photometric and R-band polarimetric monitoring of BL Lac using 70-cm AZT-8 (CrAO, Ukraine) and 0.4-m LX-200 (St.Petersburg, Russia) telescopes, as a part of GASP project. As reported in Atel#4028, this blazar was found by Fermi LAT in active state on 2012 April 9. Our data show that a sharp optical maximum was reached on the date 2012-04-08UT02:20, R=13.10, while on 2012-04-11UT01:30 R=13.40.

  5. High heat load synchrotron optics

    SciTech Connect

    Mills, D.M.

    1992-08-01

    Third generation synchrotron radiation sources currently being constructed worldwide will produce x-ray beams of unparalleled power and power density these high heat fluxes coupled with the stringent dimensional requirements of the x-ray optical components pose a prodigious challenge to designers of x-ray optical elements, specifically x-ray mirrors and crystal monochromators. Although certain established techniques for the cooling of high heat flux components can be directly applied to this problem, the thermal management of high heat load x-ray optical components has several unusual aspects that may ultimately lead to unique solutions. This manuscript attempts to summarize the various approaches currently being applied to this undertaking and to point out the areas of research that require further development.

  6. Different ways to active optical frequency standards

    NASA Astrophysics Data System (ADS)

    Pan, Duo; Xue, Xiaobo; Zhang, Xiaogang; Chen, Jingbiao

    2016-06-01

    Active optical frequency standard, or active optical clock, is a new concept of optical frequency standard, where a weak feedback with phase coherence information in optical bad-cavity limitation is formed, and the continuous self-sustained coherent stimulated emission between two atomic transition levels with population inversion is realized. Through ten years of both theoretical and experimental exploration, the narrow linewidth and suppression of cavity pulling effect of active optical frequency standard have been initially proved. In this paper, after a simple review, we will mainly present the most recent experimental progresses of active optical frequency standards in Peking University, including 4-level cesium active optical frequency standards and active Faraday optical frequency standards. The future development of active optical frequency standards is also discussed.

  7. Human psychophysiological activity monitoring methods using fiber optic sensors

    NASA Astrophysics Data System (ADS)

    Zyczkowski, M.; Uzieblo-Zyczkowska, B.

    2010-10-01

    The paper presents the concept of fiber optic sensor system for human psycho-physical activity detection. A fiber optic sensor that utilizes optical phase interferometry or intensity in modalmetric to monitor a patient's vital signs such as respiration cardiac activity, blood pressure and body's physical movements. The sensor, which is non-invasive, comprises an optical fiber interferometer that includes an optical fiber proximately situated to the patient so that time varying acusto-mechanical signals from the patient are coupled into the optical fiber. The system can be implemented in embodiments ranging form a low cost in-home to a high end product for in hospital use.

  8. Active optics with a minimum number of actuators

    NASA Astrophysics Data System (ADS)

    Lemaitre, Gerard R.

    2014-06-01

    Optics for astronomy implies powerful developments of active and adaptive optics methods applied to instrumentation from X-rays to the near infrared for the design of telescopes, spectrographs, and coronagraph planet finders. This presentation particularly emphasizes the development of active optics methods. Highly accurate and remarkably smooth surfaces from active optics methods allow new optical systems that use highly aspheric and non-axisymmetric - freeform - surfaces. Depending on the goal and performance required for a deformable optical surface, elasticity theory analysis is carried out either with small deformation thin plate theory, large deformation thin plate theory, shallow spherical shell theory, or the weakly conical shell theory. A mirror thickness distribution is then determined as a function of associated bending actuators and boundary conditions. For a given optical shape to generate, one searches for optical solutions with a minimum number of actuators.

  9. High-Temperature Optical Sensor

    NASA Technical Reports Server (NTRS)

    Adamovsky, Grigory; Juergens, Jeffrey R.; Varga, Donald J.; Floyd, Bertram M.

    2010-01-01

    A high-temperature optical sensor (see Figure 1) has been developed that can operate at temperatures up to 1,000 C. The sensor development process consists of two parts: packaging of a fiber Bragg grating into a housing that allows a more sturdy thermally stable device, and a technological process to which the device is subjected to in order to meet environmental requirements of several hundred C. This technology uses a newly discovered phenomenon of the formation of thermally stable secondary Bragg gratings in communication-grade fibers at high temperatures to construct robust, optical, high-temperature sensors. Testing and performance evaluation (see Figure 2) of packaged sensors demonstrated operability of the devices at 1,000 C for several hundred hours, and during numerous thermal cycling from 400 to 800 C with different heating rates. The technology significantly extends applicability of optical sensors to high-temperature environments including ground testing of engines, flight propulsion control, thermal protection monitoring of launch vehicles, etc. It may also find applications in such non-aerospace arenas as monitoring of nuclear reactors, furnaces, chemical processes, and other hightemperature environments where other measurement techniques are either unreliable, dangerous, undesirable, or unavailable.

  10. High resolution optical DNA mapping

    NASA Astrophysics Data System (ADS)

    Baday, Murat

    Many types of diseases including cancer and autism are associated with copy-number variations in the genome. Most of these variations could not be identified with existing sequencing and optical DNA mapping methods. We have developed Multi-color Super-resolution technique, with potential for high throughput and low cost, which can allow us to recognize more of these variations. Our technique has made 10--fold improvement in the resolution of optical DNA mapping. Using a 180 kb BAC clone as a model system, we resolved dense patterns from 108 fluorescent labels of two different colors representing two different sequence-motifs. Overall, a detailed DNA map with 100 bp resolution was achieved, which has the potential to reveal detailed information about genetic variance and to facilitate medical diagnosis of genetic disease.

  11. High-sweeping-speed optically synchronized dual-channel terahertz-signal generator for driving a superconducting tunneling mixer and its application to active gas sensing.

    PubMed

    Oh, Kyoung-Hwan; Shimizu, Naofumi; Kohjiro, Satoshi; Kikuchi, Ken'ichi; Wakatsuki, Atsushi; Kukutsu, Naoya; Kado, Yuichi

    2009-10-12

    We propose a high-sweeping-speed optically synchronized dual-channel terahertz (THz) signal generator for an active gas-sensing system with a superconductor-insulator-superconductor (SIS) mixer. The generator can sweep a frequency range from 200 to 500 GHz at a speed of 375 GHz/s and a frequency resolution of 500 MHz. With the developed gas-sensing system, a gas-absorption-line measurement was successfully carried out with N(2)O gas in that frequency range.

  12. Optics assembly for high power laser tools

    DOEpatents

    Fraze, Jason D.; Faircloth, Brian O.; Zediker, Mark S.

    2016-06-07

    There is provided a high power laser rotational optical assembly for use with, or in high power laser tools for performing high power laser operations. In particular, the optical assembly finds applications in performing high power laser operations on, and in, remote and difficult to access locations. The optical assembly has rotational seals and bearing configurations to avoid contamination of the laser beam path and optics.

  13. Investigation of active regions at high resolution by balloon flights of the Solar Optical Universal Polarimeter (SOUP)

    NASA Technical Reports Server (NTRS)

    Tarbell, T.; Frank, Z.; Gilbreth, C.; Shine, R.; Title, A.; Topka, K.; Wolfson, J.

    1989-01-01

    SOUP is a versatile, visible-light solar observatory, built for space or balloon flight. It is designed to study magnetic and velocity fields in the solar atmosphere with high spatial resolution and temporal uniformity, which cannot be achieved from the surface of the earth. The SOUP investigation is carried out by the Lockheed Palo Alto Research Laboratory, under contract to NASA's Marshall Space Flight Center. Co-investigators include staff members at a dozen observatories and universities in the U.S. and Europe. The primary objectives of the SOUP experiment are: to measure vector magnetic and velocity fields in the solar atmosphere with much better spatial resolution than can be achieved from the ground; to study the physical processes that store magnetic energy in active regions and the conditions that trigger its release; and to understand how magnetic flux emerges, evolves, combines, and disappears on spatial scales of 400 to 100,000 km. SOUP is designed to study intensity, magnetic, and velocity fields in the photosphere and low chromosphere with 0.5 arcsec resolution, free of atmospheric disturbances. The instrument includes: a 30 cm Cassegrain telescope; an active mirror for image stabilization; broadband film and TV cameras; a birefringent filter, tunable over 5100 to 6600 A with 0.05 A bandpass; a 35 mm film camera and a digital CCD camera behind the filter; and a high-speed digital image processor.

  14. Active Star Architectures For Fiber Optics Ethernet

    NASA Astrophysics Data System (ADS)

    Linde, Yoseph L.

    1988-12-01

    Ethernet, and the closely related IEEE 802.3 CSMA/CD standard (Carrier Sense Multiple Access with Collision Detection), is probably the widest used method for high speed Local Area Networks (LANs). The original Ethernet medium was baseband coax but the wide acceptance of the system necessitated the ability to use Ethernet on a variety of media. So far the use of Ethernet on Thin Coax (CheaperNet), Twisted Pair (StarLan) and Broadband Coax has been standardized. Recently, an increased interest in Fiber Optic based LANs resulted in a formation of an IEEE group whose charter is to recommend approaches for Active and Passive Fiber Optic Ethernet systems. The various approaches which are being considered are described in this paper with an emphasis on Active Star based systems.

  15. Production of high optical purity l-lactic acid from waste activated sludge by supplementing carbohydrate: effect of temperature and pretreatment time.

    PubMed

    Jian, Qiwei; Li, Xiang; Chen, Yinguang; Liu, Yanan; Pan, Yin

    2016-10-01

    It has been widely accepted that the most environmentally beneficial way to treat waste activated sludge (WAS), the byproduct of municipal wastewater treatment plant, is to recover the valuable organic acid. However, the bio-conversion of lactic acid, one of the high added-value chemical, is seldom reported from WAS fermentation. In this paper, l-lactic acid was observed dominant in the WAS fermentation liquid with carbohydrate addition at ambient temperature. Furthermore, the effect of temperature on l-lactic acid and d-lactic acid production was fully discussed: two isomers were rapidly produced and consumed up in one day at mesophilic condition; and almost optically pure l-lactic acid was generated at thermophilic condition, yet time-consuming with yield of l-lactic acid enhancing by 52.9% compared to that at ambient temperature. The study mechanism showed that mesophilic condition was optimal for both production and consumption of l-lactic acid and d-lactic acid, while consumption of l-lactic acid and production of d-lactic acid were severely inhibited at thermophilic condition. Therefore, by maintaining thermophilic for 4 h in advance and subsequently fermenting mesophilic for 34 h, the concentration of l-lactic acid with optical activity of 98.3% was improved to 16.6 ± 0.5 g COD/L at a high specific efficiency of 0.6097/d.

  16. Evolution of the optical and hard X-ray activity of AM Her in a season dominated by the high states

    NASA Astrophysics Data System (ADS)

    Šimon, Vojtěch

    2016-07-01

    The long-term activity of AM Her, the prototype of polars, consists of interchanging high and low states. This analysis uses the data from the BAT/ Swift, MAXI/ ISS, and AAVSO data archives (including long CCD V-band night series) for investigating the relation of the time evolution of intensities in the hard X-ray, medium/hard X-ray, and the optical bands on super-orbital timescale in a season dominated by the long high-state episodes. The observations mapped the relation of the cyclotron and bremsstrahlung luminosities in such episodes. Although an increase of intensity of the cyclotron emission is generally accompanied by a brightening of the bremsstrahlung component, this relation differs for the individual high-state episodes. These variations were accompanied by the large changes of the optical modulation. In my view, all of these variations suggest variations of the dimensions and structure of the cyclotron emitting region(s), not only the changes of the mass accretion rate. The activity during a decline (much less steep than the state transition) from an initial very bright peak can be explained by a gradual evolution of the conditions in stratified shock regions in a single high state episode. The observed behavior in the neighboring high-state episodes is also important for explaining the mechanisms which cause the low state between them. In the interpretation, some low-state episodes cause that AM Her develops a different accretion mode than the one before entering the low state. Each high-state episode is a complex phenomenon in the history of accretion in this system.

  17. High pressure optical combustion probe

    SciTech Connect

    Woodruff, S.D.; Richards, G.A.

    1995-06-01

    The Department of Energy`s Morgantown Energy Technology Center has developed a combustion probe for monitoring flame presence and heat release. The technology involved is a compact optical detector of the OH radical`s UV fluorescence. The OH Monitor/Probe is designed to determine the flame presence and provide a qualitative signal proportional to the flame intensity. The probe can be adjusted to monitor a specific volume in the combustion zone to track spatial fluctuations in the flame. The probe is capable of nanosecond time response and is usually slowed electronically to fit the flame characteristics. The probe is a sapphire rod in a stainless steel tube which may be inserted into the combustion chamber and pointed at the flame zone. The end of the sapphire rod is retracted into the SS tube to define a narrow optical collection cone. The collection cone may be adjusted to fit the experiment. The fluorescence signal is collected by the sapphire rod and transmitted through a UV transmitting, fused silica, fiber optic to the detector assembly. The detector is a side window photomultiplier (PMT) with a 310 run line filter. A Hamamatsu photomultiplier base combined with a integral high voltage power supply permits this to be a low voltage device. Electronic connections include: a power lead from a modular DC power supply for 15 VDC; a control lead for 0-1 volts to control the high voltage level (and therefore gain); and a lead out for the actual signal. All low voltage connections make this a safe and easy to use device while still delivering the sensitivity required.

  18. Plasmonic Biofoam: A Versatile Optically Active Material.

    PubMed

    Tian, Limei; Luan, Jingyi; Liu, Keng-Ku; Jiang, Qisheng; Tadepalli, Sirimuvva; Gupta, Maneesh K; Naik, Rajesh R; Singamaneni, Srikanth

    2016-01-13

    Owing to their ability to confine and manipulate light at the nanoscale, plasmonic nanostructures are highly attractive for a broad range of applications. While tremendous progress has been made in the synthesis of size- and shape-controlled plasmonic nanostructures, their integration with other materials and application in solid-state is primarily through their assembly on rigid two-dimensional (2D) substrates, which limits the plasmonically active space to a few nanometers above the substrate. In this work, we demonstrate a simple method to create plasmonically active three-dimensional biofoams by integrating plasmonic nanostructures with highly porous biomaterial aerogels. We demonstrate that plasmonic biofoam is a versatile optically active platform that can be harnessed for numerous applications including (i) ultrasensitive chemical detection using surface-enhanced Raman scattering; (ii) highly efficient energy harvesting and steam generation through plasmonic photothermal heating; and (iii) optical control of enzymatic activity by triggered release of biomolecules encapsulated within the aerogel. Our results demonstrate that 3D plasmonic biofoam exhibits significantly higher sensing, photothermal, and loading efficiency compared to conventional 2D counterparts. The design principles and processing methodology of plasmonic aerogels demonstrated here can be broadly applied in the fabrication of other functional foams. PMID:26630376

  19. Measurement of optical activity of honey bee

    NASA Astrophysics Data System (ADS)

    Ortiz-Gutiérrez, Mauricio; Olivares-Pérez, Arturo; Salgado-Verduzco, Marco Antonio; Ibarra-Torres, Juan Carlos

    2016-03-01

    Optical activity of some substances, such as chiral molecules, often exhibits circular birefringence. Circular birefringence causes rotation of the vibration plane of the plane polarized light as it passes through the substance. In this work we present optical characterization of honey as function of the optical activity when it is placed in a polariscope that consists of a light source and properly arranged polarizing elements.

  20. Towards Depth-Resolved Optical Imaging of Cardiac Electrical Activity.

    PubMed

    Walton, Richard D; Bernus, Olivier

    2015-01-01

    The spatiotemporal dynamics of arrhythmias are likely to be complex three-dimensional phenomena. Yet, the lack of high-resolution three-dimensional imaging techniques, both in the clinic and the experimental lab, limits our ability to better understand the mechanisms of such arrhythmias. Optical mapping using voltage-sensitive dyes is a widely used tool in experimental electrophysiology. It has been known for decades that even in its most basic application, epi-fluorescence, the optical signal contains information from within a certain intramural volume. Understanding of this fundamental property of optical signals has paved the way towards novel three-dimensional optical imaging techniques. Here, we review our current understanding of the three-dimensional nature of optical signals; how penetration depths of cardiac optical imaging can be improved by using novel imaging modalities and finally, we highlight new techniques inspired from optical tomography and aiming at full depth-resolved optical mapping of cardiac electrical activity. PMID:26238062

  1. Trifluoromethyl nitrones: from fluoral to optically active hydroxylamines.

    PubMed

    Milcent, Thierry; Hinks, Nathan; Bonnet-Delpon, Danièle; Crousse, Benoit

    2010-06-28

    Trifluoromethyl nitrones were obtained in high yields by condensation of various hydroxylamines with trifluoroacetaldehyde hydrate. The nucleophilic diastereoselective additions of organometallic reagents to these nitrones afforded the corresponding optically active trifluoroethyl hydroxylamines in good yields. PMID:20458418

  2. Giant nonlinear optical activity in a plasmonic metamaterial

    NASA Astrophysics Data System (ADS)

    Ren, Mengxin; Plum, Eric; Xu, Jingjun; Zheludev, Nikolay I.

    2012-05-01

    In 1950, a quarter of a century after his first-ever nonlinear optical experiment when intensity-dependent absorption was observed in uranium-doped glass, Sergey Vavilov predicted that birefringence, dichroism and polarization rotatory power should be dependent on light intensity. It required the invention of the laser to observe the barely detectable effect of light intensity on the polarization rotatory power of the optically active lithium iodate crystal, the phenomenon now known as the nonlinear optical activity, a high-intensity counterpart of the fundamental optical effect of polarization rotation in chiral media. Here we report that a plasmonic metamaterial exhibits nonlinear optical activity 30 million times stronger than lithium iodate crystals, thus transforming this fundamental phenomenon of polarization nonlinear optics from an esoteric phenomenon into a major effect of nonlinear plasmonics with potential for practical applications.

  3. Mechanistic switch leading to highly efficient chirality transfer in Pd(0)-catalyzed coupling-cyclization of aryl iodides with 1:1 acid-base salts of 2,3-allenoic acids and L-(-)-cinchonidine or D-(+)-/L-(-)-alpha-methylbenzylamine. Enantioselective synthesis of highly optically active 3-aryl polysubstituted butenolides.

    PubMed

    Ma, Shengming; Shi, Zhangjie

    2002-03-01

    An efficient methodology provides an easy access to highly optically active polysubstituted butenolides starting from aryl halides and 1:1:salts of optically active 2,3-allenoic acid-base via an oxidative addition-coordinative cyclization-reductive elimination mechanism, which led to the high efficiency of this chirality isomerization reaction.

  4. Optical magnetism and optical activity in nonchiral planar plasmonic metamaterials.

    PubMed

    Li, Guozhou; Li, Qiang; Yang, Lizhen; Wu, Lijun

    2016-07-01

    We investigate optical magnetism and optical activity in a simple planar metamolecule composed of double U-shaped metal split ring resonators (SRRs) twisted by 90° with respect to one another. Compared to a single SRR, the resonant energy levels are split and strong magnetic response can be observed due to inductive and conductive coupling. More interestingly, the nonchiral structures exhibit strong optical gyrotropy (1100°/λ) under oblique incidence, benefiting from the strong electromagnetic coupling. A chiral molecule model is proposed to shed light on the physical origin of optical activity. These artificial chiral metamaterials could be utilized to control the polarization of light and promise applications in enantiomer sensing-based medicine, biology, and drug development.

  5. Optical design of a high power fiber optic coupler

    SciTech Connect

    English, R.E. Jr.; Halpin, J.M.; House, F.A.; Paris, R.D.

    1991-06-19

    Fiber optic beam delivery systems are replacing conventional mirror delivery systems for many reasons (e.g., system flexibility and redundancy, stability, and ease of alignment). Commercial products are available that use of fiber optic delivery for laser surgery and materials processing. Also, pump light of dye lasers can be delivered by optical fibers. Many laser wavelengths have been transported via optical fibers; high power delivery has been reported for argon, Nd:YAG, and excimer. We have been developing fiber optic beam delivery systems for copper vapor laser light; many of the fundamental properties of these systems are applicable to other high power delivery applications. A key element of fiber optic beam delivery systems is the coupling of laser light into the optical fiber. For our application this optical coupler must be robust to a range of operating parameters and laser characteristics. We have access to a high power copper vapor laser beam that is generated by a master oscillator/power amplifier (MOPA) chain comprised of three amplifiers. The light has a pulse width of 40--50 nsec with a repetition rate of about 4 kHz. The average power (nominal) to be injected into a fiber is 200 W. (We will refer to average power in this paper.) In practice, the laser beam's direction and collimation change with time. These characteristics plus other mechanical and operational constraints make it difficult for our coupler to be opto-mechanically referenced to the laser beam. We describe specifications, design, and operation of an optical system that couples a high-power copper vapor laser beam into a large core, multimode fiber. The approach used and observations reported are applicable to fiber optic delivery applications. 6 refs., 6 figs.

  6. Optical receiver for high-speed communication

    NASA Astrophysics Data System (ADS)

    Mitchell, Paul A.; Grib, Valerie J.

    2010-04-01

    For through-the-air optical communication applications, we present a high speed detector module with high bandwidth and large active area. The detector has achieved a rise time of 220 pS with a full-width-half-max of 420 pS. Data rates are expected to approach 2 GHz. The active area of the input window is 12 mm, giving a large collection surface for through-the-air applications. The detector module includes an integrated power supply having low power consumption. In comparison with other detector technologies, this new detector exceeds the speed of conventional photomultiplier designs by 3 to 5 times. In comparison with microchannel plate detectors, the speed is comparable, but the throughput of the new detector is much higher - tens of microamperes of signal current can be obtained indefinitely. Optical communication applications can be served by two different designs. In the first case, the module utilizes gain based on ordinary secondary emission materials to achieve current gains of 1500. This design is suitable for applications at the limit of the detector's bandwidth where light power is relatively high. In another design, the secondary emission material was changed to diamond film which allows five times higher gain. While the current design uses an ordinary, blue sensitive input light conversion material, higher efficiency materials are in development for signals at longer wavelength.

  7. Passive and Active Fiber Optic Components

    NASA Astrophysics Data System (ADS)

    Digonnet, Michel Jean-Francois

    This thesis is concerned with the development and characterization of both passive and active fiber-optic components for applications in single-mode fiber systems, in particular in the new technology of fiber sensors and signal processors. These components include single-mode fiber directional couplers, vital to many optical fiber systems, all-fiber wavelength multiplexers, with potential applications in communication systems and active fiber devices, and single-crystal fiber lasers and amplifiers as miniature light sources and signal regenerators. The fiber directional couplers involved in this work, fabricated by a polishing process, are described in detail. Experimental characterization of their coupling, loss and unique tuning properties, and their respective dependence on the coupler geometrical parameters, are reported. A theoretical model of fiber-to-fiber coupling is also developed and shown to be a very useful and accurate tool in the design and study of this type of fiber couplers. The dependence of the coupling properties of fiber couplers on the signal wavelength is studied both theoretically and experimentally for applications in wavelength division multiplexing. All-fiber multiplexers exhibiting a good wavelength selectivity and unique tunability are described and shown to operate according to the coupler model. Work on active fiber devices explores the potential of the new technology of single-crystal fibers grown by the laser-heated floating-zone technique. The status of crystal fiber growth is reported, together with the basic physical and optical characteristics of these fibers. A theoretical model of the effects of fiber model structure on the gain and laser operation of active fibers is also developed to predict the performance of lasers and amplifiers in a fiber form. Several conceptual pumping schemes are described which offer solutions to the difficult problem of optically pumping small diameter fiber amplifiers. The experimental

  8. High cell density cultivation of Pseudomonas putida strain HKT554 and its application for optically active sulfoxide production.

    PubMed

    Ramadhan, Said Hamad; Matsui, Toru; Nakano, Kazuma; Minami, Hirofumi

    2013-03-01

    Culture conditions with Pseudomonas putida strain HKT554, expressing naphthalene dioxygenase, known as the biocatalyst showing wide substrate specificity, were optimized for high cell density cultivation (HCDC). Culture in a medium TK-B modified from that for HCDC of Escherichia coli with glucose fed-batch and dissolved oxygen stat resulted in a high cell density growth of 114 g dry cell/l at 40 h of cultivation. This system was further applied for S-(+)-methyl phenyl sulfoxide (MPSO) production from methyl phenyl sulfide. Addition of nonpolar organic solvent, such as n-hexadecane, greatly enhanced the MPSO production due to the prevention of substrate evaporation, resulting in a MPSO production up to 39 mM in 30 h with a conversion rate of 95.7 mol%.

  9. Electro-Optical High-Voltage Sensors

    NASA Technical Reports Server (NTRS)

    Gottsche, Allan; Johnston, Alan R.

    1992-01-01

    Electro-optical sensors for measuring high voltages developed for use in automatically controlled power-distribution systems. Sensors connected to optoelectronic interrogating equipment by optical fibers. Because sensitive material and optical fibers are all dielectric, no problem in electrically isolating interrogating circuitry from high voltage, and no need for voltage dividers. Sensor signals transmitted along fibers immune to electromagnetic noise at radio and lower frequencies.

  10. High Bandwidth Electro-optic Scanner for Optical Data Storage

    NASA Astrophysics Data System (ADS)

    Zhai, Jinhui; Huang, Yuhong; Schroeck, Steve; Messner, W.; Stancil, Daniel D.; Schlesinger, T. E.

    2000-02-01

    Beam deflectors can be used as fine tracking actuators to improve track access time and data rate in future high performance optical disk drives. In this paper we report on the use of an electro-optic (EO) scanner for optical data storage. Track following has been accomplished using this EO actuator with a servo bandwidth of 200 kHz, and single-stage high-speed track switching/following has been demonstrated in a new optical head tracking system with reduced offset. A fine tracking experiment has also been demonstrated using an EO actuator with a voice coil motor (VCM) actuator to extend the fine tracking range. A new compensator design method, the PQ method, has been used for this scanner/VCM compound actuator system. Significant improvements in track switching/following speed are demonstrated with the scanner/VCM compound actuator as compared to tracking with the VCM actuator alone.

  11. Active optics, adaptive optics, and laser guide stars.

    PubMed

    Hubin, N; Noethe, L

    1993-11-26

    Optical astronomy is crucial to our understanding of the universe, but the capabilities of ground-based telescopes are severely limited by the effects of telescope errors and of the atmosphere on the passage of light. Recently, it has become possible to construct inbuilt corrective devices that can compensate for both types of degradations as observations are conducted. For full use of the newly emerged class of 8-meter telescopes, such active corrective capabilities, known as active and adaptive optics, are essential. Some physical limitations in the adaptive optics field can be overcome by artificially created reference stars, called laser guide stars. These new technologies have lately been applied with success to some medium and very large telescopes. PMID:17736819

  12. THE NATURE OF OPTICALLY DULL ACTIVE GALACTIC NUCLEI IN COSMOS

    SciTech Connect

    Trump, Jonathan R.; Impey, Chris D.; Gabor, Jared M.; Taniguchi, Yoshi; Nagao, Tohru; Shioya, Yasuhiro; Brusa, Marcella; Civano, Francesca; Elvis, Martin; Kelly, Brandon C.; Huchra, John P.; Jahnke, Knud; Koekemoer, Anton M.; Salvato, Mara; Capak, Peter; Scoville, Nick Z.; Kartaltepe, Jeyhan S.; Lanzuisi, Giorgio; McCarthy, Patrick J.; Maineri, Vincenzo

    2009-11-20

    We present infrared, optical, and X-ray data of 48 X-ray bright, optically dull active galactic nuclei (AGNs) in the COSMOS field. These objects exhibit the X-ray luminosity of an AGN but lack broad and narrow emission lines in their optical spectrum. We show that despite the lack of optical emission lines, most of these optically dull AGNs are not well described by a typical passive red galaxy spectrum: instead they exhibit weak but significant blue emission like an unobscured AGN. Photometric observations over several years additionally show significant variability in the blue emission of four optically dull AGNs. The nature of the blue and infrared emission suggest that the optically inactive appearance of these AGNs cannot be caused by obscuration intrinsic to the AGNs. Instead, up to approx70% of optically dull AGNs are diluted by their hosts, with bright or simply edge-on hosts lying preferentially within the spectroscopic aperture. The remaining approx30% of optically dull AGNs have anomalously high f{sub X} /f{sub O} ratios and are intrinsically weak, not obscured, in the optical. These optically dull AGNs are best described as a weakly accreting AGN with a truncated accretion disk from a radiatively inefficient accretion flow.

  13. Vibrational Raman optical activity of biological molecules

    NASA Astrophysics Data System (ADS)

    Barron, L. D.; Hecht, Lutz; Wen, Z. Q.; Ford, Steven J.; Bell, A. F.

    1993-06-01

    Advances in Raman optical activity (ROA) instrumentation based on the employment of a backscattering geometry together with a cooled backthinned CCD detector, a holographic notch filter, and a high-efficiency single-grating spectrograph have now enhanced the sensitivity to the level necessary to provide vibrational ROA spectra of most biological molecules in aqueous solution. Results on peptides and proteins show features originating in coupled C(alpha )-H and N-H deformations of the peptide backbone which appear to be sensitive to the secondary conformation including loop and turn structures. Also carbohydrates show many features characteristic of the central aspects of carbohydrate architecture, with effects from the glycosidic link in oligosaccharides particularly prominent. Preliminary ROA spectra of pyrimidine nucleosides appear to reflect the mutual orientation of the sugar and base rings and the dominant furanose conformations.

  14. Vibrational Raman optical activity of ketose monosaccharides

    NASA Astrophysics Data System (ADS)

    Bell, Alasdair F.; Hecht, Lutz; Barron, Laurence D.

    1995-07-01

    The vibrational Raman optical activity (ROA) spectra of the four ketose sugars D-fructose, L-sorbose, D-tagatose and D-psicose in aqueous solution, which have been measured in backscattering in the range ≈250-1500 cm -1, are reported. These results are combined with those from a previous ROA study of aldose and pentose sugars in an attempt to establish new vibrational assignments and to verify old ones. The high information content of these spectra provides a new perspective on all the central features of monosaccharide stereochemistry including dominant anomeric configuration, ring conformation, exocyclic CH 2OH group conformation and relative disposition of the hydroxyl groups around the ring.

  15. Chiral THz metamaterial with tunable optical activity

    SciTech Connect

    Zhou, Jiangfeng; Taylor, Antoinette; O' Hara, John; Chowdhury, Roy; Zhao, Rongkuo; Soukoullis, Costas M

    2010-01-01

    Optical activity in chiral metamaterials is demonstrated in simulation and shows actively tunable giant polarization rotation at THz frequencies. Electric current distributions show that pure chirality is achieved by our bi-Iayer chiral metamaterial design. The chirality can be optically controlled by illumination with near-infrared light. Optical activity, occurring in chiral materials such as DNA, sugar and many other bio-molecules, is a phenomenon of great importance to many areas of science including molecular biology, analytical chemistry, optoelectronics and display applications. This phenomenon is well understood at an effective medium level as a magnetic/electric moment excited by the electric/magnetic field of the incident electromagnetic (EM) wave. Usually, natural chiral materials exhibit very weak optical activity e.g. a gyrotropic quartz crystal. The optical activity of chiral metamaterials, however, can be five orders of magnitude stronger. Chiral metamaterials are made of sub-wavelength resonators lacking symmetry planes. The asymmetry allows magnetic moments to be excited by the electric field of the incident EM wave and vice versa. Recently, chiral metamaterials have been demonstrated and lead to prospects in giant optical activity, circular dichroism, negative refraction and reversing the Casmir force. These fascinating optical properties require strong chirality, which may be designed through the microscopic structure of chiral metamaterials. However, these metamaterials have a fixed response function, defined by the geometric structuring, which limits their ability to manipulate EM waves. Active metamaterials realize dynamic control of response functions and have produced many influential applications such as ultra-fast switching devices, frequency and phase modulation and memory devices. Introducing active designs to chiral metamaterials will give additional freedom in controlling the optical activity, and therefore enable dynamic manipulation

  16. Stem cell tracking with optically active nanoparticles

    PubMed Central

    Gao, Yu; Cui, Yan; Chan, Jerry KY; Xu, Chenjie

    2013-01-01

    Stem-cell-based therapies hold promise and potential to address many unmet clinical needs. Cell tracking with modern imaging modalities offers insight into the underlying biological process of the stem-cell-based therapies, with the goal to reveal cell survival, migration, homing, engraftment, differentiation, and functions. Adaptability, sensitivity, resolution, and non-invasiveness have contributed to the longstanding use of optical imaging for stem cell tracking and analysis. To identify transplanted stem cells from the host tissue, optically active probes are usually used to label stem cells before the administration. In comparison to the traditional fluorescent probes like fluorescent proteins and dyes, nanoparticle-based probes are advantageous in terms of the photo-stabilities and minimal changes to the cell phenotype. The main focus here is to overview the recent development of optically active nanoparticles for stem cells tracking. The related optical imaging modalities include fluorescence imaging, photoacoustic imaging, Raman and surface enhanced Raman spectroscopy imaging. PMID:23638335

  17. Recent optical activity of Mrk 421

    NASA Astrophysics Data System (ADS)

    Semkov, E.; Bachev, R.; Strigachev, A.; Ibryamov, S.; Peneva, S.; Gupta, A. C.

    2013-04-01

    Our BVRI optical observations of Mrk 421 were performed within the multiwavelength international campaign (December 2012-June 2013), with the participation of GASP-WEBT, Swift, MAGIC, VLBA, NuSTAR, Fermi, VERITAS, F-GAMMA and other collaborations. Following the reports of enhanced X-ray and gamma activity of Mrk 421 (ATel #4978, ATel #4977, ATel #4976, ATel #4974, ATel #4918), we observed this blazar with the optical telescopes of the National Astronomical Observatory Rozhen and the Astronomical Observatory Belogradchik, Bulgaria.

  18. Photovoltaic concentrator assembly with optically active cover

    DOEpatents

    Plesniak, Adam P

    2014-01-21

    A photovoltaic concentrator assembly that includes a housing that defines an internal volume and includes a rim, wherein the rim defines an opening into the internal volume, a photovoltaic cell positioned in the internal volume, and an optical element that includes an optically active body and a flange extending outward from the body, wherein the flange is sealingly engaged with the rim of the housing to enclose the internal volume.

  19. High-Temperature Optical Window Design

    NASA Technical Reports Server (NTRS)

    Roeloffs, Norman; Taranto, Nick

    1995-01-01

    A high-temperature optical window is essential to the optical diagnostics of high-temperature combustion rigs. Laser Doppler velocimetry, schlieren photography, light sheet visualization, and laser-induced fluorescence spectroscopy are a few of the tests that require optically clear access to the combustor flow stream. A design was developed for a high-temperature window that could withstand the severe environment of the NASA Lewis 3200 F Lean Premixed Prevaporized (LPP) Flame Tube Test Rig. The development of this design was both time consuming and costly. This report documents the design process and the lessons learned, in an effort to reduce the cost of developing future designs for high-temperature optical windows.

  20. Actively heated high-resolution fiber-optic-distributed temperature sensing to quantify streambed flow dynamics in zones of strong groundwater upwelling

    NASA Astrophysics Data System (ADS)

    Briggs, Martin A.; Buckley, Sean F.; Bagtzoglou, Amvrossios C.; Werkema, Dale D.; Lane, John W.

    2016-07-01

    Zones of strong groundwater upwelling to streams enhance thermal stability and moderate thermal extremes, which is particularly important to aquatic ecosystems in a warming climate. Passive thermal tracer methods used to quantify vertical upwelling rates rely on downward conduction of surface temperature signals. However, moderate to high groundwater flux rates (>-1.5 m d-1) restrict downward propagation of diurnal temperature signals, and therefore the applicability of several passive thermal methods. Active streambed heating from within high-resolution fiber-optic temperature sensors (A-HRTS) has the potential to define multidimensional fluid-flux patterns below the extinction depth of surface thermal signals, allowing better quantification and separation of local and regional groundwater discharge. To demonstrate this concept, nine A-HRTS were emplaced vertically into the streambed in a grid with ˜0.40 m lateral spacing at a stream with strong upward vertical flux in Mashpee, Massachusetts, USA. Long-term (8-9 h) heating events were performed to confirm the dominance of vertical flow to the 0.6 m depth, well below the extinction of ambient diurnal signals. To quantify vertical flux, short-term heating events (28 min) were performed at each A-HRTS, and heat-pulse decay over vertical profiles was numerically modeled in radial two dimension (2-D) using SUTRA. Modeled flux values are similar to those obtained with seepage meters, Darcy methods, and analytical modeling of shallow diurnal signals. We also observed repeatable differential heating patterns along the length of vertically oriented sensors that may indicate sediment layering and hyporheic exchange superimposed on regional groundwater discharge.

  1. High accuracy optical rate sensor

    NASA Technical Reports Server (NTRS)

    Uhde-Lacovara, J.

    1990-01-01

    Optical rate sensors, in particular CCD arrays, will be used on Space Station Freedom to track stars in order to provide inertial attitude reference. An algorithm to provide attitude rate information by directly manipulating the sensor pixel intensity output is presented. The star image produced by a sensor in the laboratory is modeled. Simulated, moving star images are generated, and the algorithm is applied to this data for a star moving at a constant rate. The algorithm produces accurate derived rate of the above data. A step rate change requires two frames for the output of the algorithm to accurately reflect the new rate. When zero mean Gaussian noise with a standard deviation of 5 is added to the simulated data of a star image moving at a constant rate, the algorithm derives the rate with an error of 1.9 percent at a rate of 1.28 pixels per frame.

  2. Manifestation of optical activity in different materials

    NASA Astrophysics Data System (ADS)

    Konstantinova, A. F.; Golovina, T. G.; Konstantinov, K. K.

    2014-07-01

    Various manifestations of optical activity (OA) in crystals and organic materials are considered. Examples of optically active enantiomorphic and nonenantiomorphic crystals of 18 symmetry classes are presented. The OA of enantiomorphic organic materials as components of living nature (amino acids, sugars, and proteins) is analyzed. Questions related to the origin of life on earth are considered. Examples of differences in the enantiomers of drugs are shown. The consequences of replacing conventional left-handed amino acids with additionally right-handed amino acids for living organisms are indicated.

  3. Design of highly reliable military avionics fiber optic data buses

    NASA Astrophysics Data System (ADS)

    Zhang, Jian-Guo

    1993-12-01

    Military avionics applications require the high reliability, which offers the challenge to design feasible avionics fiber-optic (AFO) data buses. In this paper, we present the new design methods to implement the highly reliable AFO data buses by using today's mature optoelectronic devices. To effective solve the problems associated with optical power budget and high reliability, the active-coupler architectures for both single-wavelength and multi- wavelength AFO data buses are proposed. The topologies are discussed in detail. To ensure the high-reliability data transmission on the buses, three efficient modulation techniques are presented, which can significantly reduce the complexity of optical transceivers and the processing time at receivers compared to using the modulation scheme recommended by the MIL-STD-1773. The hardware design of the proposed active-coupler-based AFO data buses is also described.

  4. An Overhead Projection Demonstration of Optical Activity

    ERIC Educational Resources Information Center

    Hill, John W.

    1973-01-01

    Describes the use of two polarizing lenses, a yellow filter, an oatmeal bos, a piece of cardboard, a 1,000 ml beaker, and an overhead projector to demonstrate compound optical activity to large classes. Indicates the presence of an accuracy within 1-2 degrees of usually acceptable data. (CC)

  5. High-Sensitivity Microwave Optics.

    ERIC Educational Resources Information Center

    Nunn, W. M., Jr.

    1981-01-01

    Describes a 3.33-cm wavelength (9 GHz) microwave system that achieves a high overall signal sensitivity and a well-collimated beam with moderate-size equipment. The system has been used to develop microwave versions of the Michelson interferometer, Bragg reflector, Brewster's law and total internal reflection, and Young's interference experiment.…

  6. 200-kV active optical fiber voltage transformer

    NASA Astrophysics Data System (ADS)

    Xu, Yan; Luo, Sunan; Ye, Miaoyuan

    1999-02-01

    The report describes a 220kV Active Optical Fiber Voltage Transformer (AOVT). The transformer is different from the passive optical fiber voltage transformer, for no optical crystal is used in the 220kV AOVT. Its principle is that a low voltage is divided for the 220kV high voltage by a capacitive divider and then is converted into a digital signal. The optical fiber is used to transfer the measured digital signal and control signal. The 220kV AOVT consists of an outdoors-high voltage measurement unit and an indoors low voltage metering and controlling unit. The optical fiber connects these units. The low voltage is effectively isolated from the high voltage by means of the optical fiber and a special power supply method which is specially designed for the outdoor high voltage unit. As a result, the safe protection is reliable for the indoor low voltage equipment and the operation staff. Compared to the conventional voltage transformer, the advantages of the 220kV AOVT are high accuracy, low cost, excellent dynamic characteristics and immunity from electromagnetic interference. The 220kV AOVT has been tested, and its accuracy could achieve +/- 0.2 percent.

  7. Technology Development for High Efficiency Optical Communications

    NASA Technical Reports Server (NTRS)

    Farr, William H.

    2012-01-01

    Deep space optical communications is a significantly more challenging operational domain than near Earth space optical communications, primarily due to effects resulting from the vastly increased range between transmitter and receiver. The NASA Game Changing Development Program Deep Space Optical Communications Project is developing four key technologies for the implementation of a high efficiency telecommunications system that will enable greater than 10X the data rate of a state-of-the-art deep space RF system (Ka-band) for similar transceiver mass and power burden on the spacecraft. These technologies are a low mass spacecraft disturbance isolation assembly, a flight qualified photon counting detector array, a high efficiency flight laser amplifier and a high efficiency photon counting detector array for the ground-based receiver.

  8. Optically transparent high temperature shape memory polymers.

    PubMed

    Xiao, Xinli; Qiu, Xueying; Kong, Deyan; Zhang, Wenbo; Liu, Yanju; Leng, Jinsong

    2016-03-21

    Optically transparent shape memory polymers (SMPs) have potential in advanced optoelectronic and other common shape memory applications, and here optically transparent shape memory polyimide is reported for the first time. The polyimide possesses a glass transition temperature (Tg) of 171 °C, higher than the Tg of other transparent SMPs reported, and the influence of molecular structure on Tg is discussed. The 120 μm thick polyimide film exhibits transmittance higher than 81% in 450-800 nm, and the possible mechanism of its high transparency is analyzed, which will benefit further research on other transparent high temperature SMPs. The transparent polyimide showed excellent thermomechanical properties and shape memory performances, and retained high optical transparency after many shape memory cycles. PMID:26686222

  9. Optical fiber sensor having an active core

    NASA Technical Reports Server (NTRS)

    Egalon, Claudio Oliveira (Inventor); Rogowski, Robert S. (Inventor)

    1993-01-01

    An optical fiber is provided. The fiber is comprised of an active fiber core which produces waves of light upon excitation. A factor ka is identified and increased until a desired improvement in power efficiency is obtained. The variable a is the radius of the active fiber core and k is defined as 2 pi/lambda wherein lambda is the wavelength of the light produced by the active fiber core. In one embodiment, the factor ka is increased until the power efficiency stabilizes. In addition to a bare fiber core embodiment, a two-stage fluorescent fiber is provided wherein an active cladding surrounds a portion of the active fiber core having an improved ka factor. The power efficiency of the embodiment is further improved by increasing a difference between the respective indices of refraction of the active cladding and the active fiber core.

  10. Anamorphic high-NA EUV lithography optics

    NASA Astrophysics Data System (ADS)

    Migura, Sascha; Kneer, Bernhard; Neumann, Jens Timo; Kaiser, Winfried; van Schoot, Jan

    2015-09-01

    EUV lithography (EUVL) for a limit resolution below 8 nm requires the numerical aperture (NA) of the projection optics to be larger than 0.50. For such a high-NA optics a configuration of 4x magnification, full field size of 26 x 33 mm² and 6'' mask is not feasible anymore. The increased chief ray angle and higher NA at reticle lead to non-acceptable mask shadowing effects. These shadowing effects can only be controlled by increasing the magnification, hence reducing the system productivity or demanding larger mask sizes. We demonstrate that the best compromise in imaging, productivity and field split is a so-called anamorphic magnification and a half field of 26 x 16.5 mm² but utilizing existing 6'' mask infrastructure. We discuss the optical solutions for such anamorphic high-NA EUVL.

  11. Asymmetric fishnet metamaterials with strong optical activity.

    PubMed

    Zhang, Yong-Liang; Jin, Wei; Dong, Xian-Zi; Zhao, Zhen-Sheng; Duan, Xuan-Ming

    2012-05-01

    We investigate the optical properties of mono- and double-layer asymmetric fishnet metamaterials with orientated elliptical holes, which exhibit exotic spectral and polarization rotating characteristics in the visible spectral range. Our results show that nontrivial orientations of the holes with respect to the reciprocal lattice vectors of the periodic lattice in both systems produce strong polarization rotation as well as additional enhanced optical transmission peaks. Analysis of the electromagnetic field distribution shows the unusual effect is produced by the spinning localized surface plasmon resonances due to the asymmetric geometry. High sensitivity of the hybridized mode on the dielectric spacing, the aspect ratio of the holes and the embedding media in double-layer structure is also observed. The dependence of spectral and polarization response on the orientation of the holes and the embedding media is useful for design of chiral metamaterials at optical frequencies and tailoring the polarization behavior of the metallic nano-structures.

  12. Photonic muscle active optics for space telescopes (active optics with 1023 actuators)

    NASA Astrophysics Data System (ADS)

    Ritter, Joe

    2009-08-01

    Presented is a novel optical system using Cis-Trans photoisomerization where nearly every molecule of a mirror substrate is itself an optically powered actuator. Primary mirrors require sub-wavelength figure (shape) error in order to achieve acceptable Strehl ratios. Traditional telescopy methods require rigid and therefore heavy mirrors and reaction structures as well as proportionally heavy and expensive spacecraft busses and launch vehicles. Areal density can be reduced by increasing actuation density. Making every molecule of a substrate an actuator approaches the limit of the areal density vs actuation design trade space. Cis-Trans photoisomerization, a reversible reorganization of molecular structure induced by light, causes a change in the shape and volume of azobenzene based molecules. Induced strain in these "photonic muscles" can be over 40%. Forces are pico-newtons/molecule. Although this molecular limit is not typically multiplied in aggregate materials we have made, considering the large number of molecules in a mole, future optimized systems may approach this limit In some π-π* mixed valence azo-polymer membranes we have made photoisomerization causes a highly controllable change in macroscopic dimension with application of light. Using different wavelengths and polarizations provides the capability to actively reversibly and remotely control membrane mirror shape and dynamics using low power lasers, instead of bulky actuators and wires, thus allowing the substitution of optically induced control for rigidity and mass. Areal densities of our photonic muscle mirrors are approximately 100 g/m2. This includes the substrate and actuators (which are of course the same). These materials are thin and flexible (similar to saran wrap) so high packing ratios are possible, suggesting the possibility of deployable JWST size mirrors weighing 6 kilograms, and the possibility of ultralightweight space telescopes the size of a football field. Photons weigh nothing

  13. Optical activity of chirally distorted nanocrystals

    NASA Astrophysics Data System (ADS)

    Tepliakov, Nikita V.; Baimuratov, Anvar S.; Baranov, Alexander V.; Fedorov, Anatoly V.; Rukhlenko, Ivan D.

    2016-05-01

    We develop a general theory of optical activity of semiconductor nanocrystals whose chirality is induced by a small perturbation of their otherwise achiral electronic subsystems. The optical activity is described using the quantum-mechanical expressions for the rotatory strengths and dissymmetry factors introduced by Rosenfeld. We show that the rotatory strengths of optically active transitions are decomposed on electric dipole and magnetic dipole contributions, which correspond to the electric dipole and magnetic dipole transitions between the unperturbed quantum states. Remarkably, while the two kinds of rotatory strengths are of the same order of magnitude, the corresponding dissymmetry factors can differ by a factor of 105. By maximizing the dissymmetry of magnetic dipole absorption one can significantly enhance the enantioselectivity in the interaction of semiconductor nanocrystals with circularly polarized light. This feature may advance chiral and analytical methods, which will benefit biophysics, chemistry, and pharmaceutical science. The developed theory is illustrated by an example of intraband transitions inside a semiconductor nanocuboid, whose rotatory strengths and dissymmetry factors are calculated analytically.

  14. HIGH AVERAGE POWER OPTICAL FEL AMPLIFIERS.

    SciTech Connect

    BEN-ZVI, ILAN, DAYRAN, D.; LITVINENKO, V.

    2005-08-21

    Historically, the first demonstration of the optical FEL was in an amplifier configuration at Stanford University [l]. There were other notable instances of amplifying a seed laser, such as the LLNL PALADIN amplifier [2] and the BNL ATF High-Gain Harmonic Generation FEL [3]. However, for the most part FELs are operated as oscillators or self amplified spontaneous emission devices. Yet, in wavelength regimes where a conventional laser seed can be used, the FEL can be used as an amplifier. One promising application is for very high average power generation, for instance FEL's with average power of 100 kW or more. The high electron beam power, high brightness and high efficiency that can be achieved with photoinjectors and superconducting Energy Recovery Linacs (ERL) combine well with the high-gain FEL amplifier to produce unprecedented average power FELs. This combination has a number of advantages. In particular, we show that for a given FEL power, an FEL amplifier can introduce lower energy spread in the beam as compared to a traditional oscillator. This properly gives the ERL based FEL amplifier a great wall-plug to optical power efficiency advantage. The optics for an amplifier is simple and compact. In addition to the general features of the high average power FEL amplifier, we will look at a 100 kW class FEL amplifier is being designed to operate on the 0.5 ampere Energy Recovery Linac which is under construction at Brookhaven National Laboratory's Collider-Accelerator Department.

  15. A high precision optical angle measuring instrument for large optical axis offsets

    NASA Astrophysics Data System (ADS)

    Xie, Jing; Tan, Zuojun

    2014-09-01

    In many industrial activities such as manufacturing and inspection, optical axis offsets measurement is an essential process for keeping and improving the quality of products. The laser autocollimation method is improved to detect the large angular displacement with high precision by using a re-imaging technology. A large optical screen made of frosted glass is located at the focal position of the objective lens instead of the detector. A precision CCD imaging system was employed to measure the displacement of the light spot on the optical screen. The sub-pixel position of center of the light spot can be obtained accurately through the centroid and Gaussian fit methods. The actual test results show that the total systematic error of the optical angle measuring instrument in the mode of measuring the range 8°×8° does not exceed 0.16'.

  16. High-impact resistance optical sensor windows

    NASA Astrophysics Data System (ADS)

    Askinazi, Joel; Ceccorulli, Mark L.; Goldman, Lee

    2011-06-01

    Recent field experience with optical sensor windows on both ground and airborne platforms has shown a significant increase in window fracturing from foreign object debris (FOD) impacts and as a by-product of asymmetrical warfare. Common optical sensor window materials such as borosilicate glass do not typically have high impact resistance. Emerging advanced optical window materials such as aluminum oxynitride offer the potential for a significant improvement in FOD impact resistance due to their superior surface hardness, fracture toughness and strength properties. To confirm the potential impact resistance improvement achievable with these emerging materials, Goodrich ISR Systems in collaboration with Surmet Corporation undertook a set of comparative FOD impact tests of optical sensor windows made from borosilicate glass and from aluminum oxynitride. It was demonstrated that the aluminum oxynitride windows could withstand up to three times the FOD impact velocity (as compared with borosilicate glass) before fracture would occur. These highly encouraging test results confirm the utility of this new highly viable window solution for use on new ground and airborne window multispectral applications as well as a retrofit to current production windows. We believe that this solution can go a long way to significantly reducing the frequency and life cycle cost of window replacement.

  17. High sensitivity optically pumped quantum magnetometer.

    PubMed

    Tiporlini, Valentina; Alameh, Kamal

    2013-01-01

    Quantum magnetometers based on optical pumping can achieve sensitivity as high as what SQUID-based devices can attain. In this paper, we discuss the principle of operation and the optimal design of an optically pumped quantum magnetometer. The ultimate intrinsic sensitivity is calculated showing that optimal performance of the magnetometer is attained with an optical pump power of 20 μW and an operation temperature of 48°C. Results show that the ultimate intrinsic sensitivity of the quantum magnetometer that can be achieved is 327 fT/Hz(½) over a bandwidth of 26 Hz and that this sensitivity drops to 130 pT/Hz(½) in the presence of environmental noise. The quantum magnetometer is shown to be capable of detecting a sinusoidal magnetic field of amplitude as low as 15 pT oscillating at 25 Hz. PMID:23766716

  18. High Sensitivity Optically Pumped Quantum Magnetometer

    PubMed Central

    Tiporlini, Valentina; Alameh, Kamal

    2013-01-01

    Quantum magnetometers based on optical pumping can achieve sensitivity as high as what SQUID-based devices can attain. In this paper, we discuss the principle of operation and the optimal design of an optically pumped quantum magnetometer. The ultimate intrinsic sensitivity is calculated showing that optimal performance of the magnetometer is attained with an optical pump power of 20 μW and an operation temperature of 48°C. Results show that the ultimate intrinsic sensitivity of the quantum magnetometer that can be achieved is 327 fT/Hz1/2 over a bandwidth of 26 Hz and that this sensitivity drops to 130 pT/Hz1/2 in the presence of environmental noise. The quantum magnetometer is shown to be capable of detecting a sinusoidal magnetic field of amplitude as low as 15 pT oscillating at 25 Hz. PMID:23766716

  19. High sensitivity optically pumped quantum magnetometer.

    PubMed

    Tiporlini, Valentina; Alameh, Kamal

    2013-01-01

    Quantum magnetometers based on optical pumping can achieve sensitivity as high as what SQUID-based devices can attain. In this paper, we discuss the principle of operation and the optimal design of an optically pumped quantum magnetometer. The ultimate intrinsic sensitivity is calculated showing that optimal performance of the magnetometer is attained with an optical pump power of 20 μW and an operation temperature of 48°C. Results show that the ultimate intrinsic sensitivity of the quantum magnetometer that can be achieved is 327 fT/Hz(½) over a bandwidth of 26 Hz and that this sensitivity drops to 130 pT/Hz(½) in the presence of environmental noise. The quantum magnetometer is shown to be capable of detecting a sinusoidal magnetic field of amplitude as low as 15 pT oscillating at 25 Hz.

  20. Actively controlled thin-shell space optics

    NASA Astrophysics Data System (ADS)

    Denoyer, Keith K.; Flint, Eric M.; Main, John A.; Lindler, Jason E.

    2003-08-01

    Increasingly, scientific and military missions require the use of space-based optical systems. For example, new capabilities are required for imaging terrestrial like planets, for surveillance, and for directed energy applications. Given the difficulties in producing and launching large optics, it is doubtful that refinements of conventional technology will meet future needs, particularly in a cost-effective manner. To meet this need, recent research has been investigating the feasibility of a new class of ultra-lightweight think-skin optical elements that combine recent advances in lightweight thermally formed materials, active materials, and novel sensing and control architectures. If successful, the approach may lead to an order of magnitude reduction in space optics areal density, improved large scale manufacturing capability, and dramatic reductions in manufacturing and launch costs. In a recent effort, a one meter thin-film mirror like structure was fabricated. This paper provides an overview of tools used to model and simulate this structure as well as results from structural dynamic testing. In addition, progress in the area of non-contact global shape control using smart materials is presented.

  1. Optically Active Porphyrin and Phthalocyanine Systems.

    PubMed

    Lu, Hua; Kobayashi, Nagao

    2016-05-25

    This review highlights and summarizes various optically active porphyrin and phthalocyanine molecules prepared using a wide range of structural modification methods to improve the design of novel structures and their applications. The induced chirality of some illustrative achiral bis-porphyrins with a chiral guest molecule is introduced because these systems are ideal for the identification and separation of chiral biologically active substrates. In addition, the relationship between CD signal and the absolute configuration of the molecule is analyzed through an analysis of the results of molecular modeling calculations. Possible future research directions are also discussed. PMID:27186902

  2. Highly Sensitive Electro-Optic Modulators

    SciTech Connect

    DeVore, Peter S

    2015-10-26

    There are very important diagnostic and communication applications that receive faint electrical signals to be transmitted over long distances for capture. Optical links reduce bandwidth and distance restrictions of metal transmission lines; however, such signals are only weakly imprinted onto the optical carrier, resulting in low fidelity transmission. Increasing signal fidelity often necessitates insertion of radio-frequency (RF) amplifiers before the electro-optic modulator, but (especially at high frequencies) RF amplification results in large irreversible distortions. We have investigated the feasibility of a Sensitive and Linear Modulation by Optical Nonlinearity (SALMON) modulator to supersede RF-amplified modulators. SALMON uses cross-phase modulation, a manifestation of the Kerr effect, to enhance the modulation depth of an RF-modulated optical wave. This ultrafast process has the potential to result in less irreversible distortions as compared to a RF-amplified modulator due to the broadband nature of the Kerr effect. Here, we prove that a SALMON modulator is a feasible alternative to an RFamplified modulator, by demonstrating a sensitivity enhancement factor greater than 20 and significantly reduced distortion.

  3. Optical signal processing for enabling high-speed, highly spectrally efficient and high capacity optical systems

    NASA Astrophysics Data System (ADS)

    Fazal, Muhammad Irfan

    The unabated demand for more capacity due to the ever-increasing internet traffic dictates that the boundaries of the state of the art maybe pushed to send more data through the network. Traditionally, this need has been satisfied by multiple wavelengths (wavelength division multiplexing), higher order modulation formats and coherent communication (either individually or combined together). WDM has the ability to reduce cost by using multiple channels within the same physical fiber, and with EDFA amplifiers, the need for O-E-O regenerators is eliminated. Moreover the availability of multiple colors allows for wavelength-based routing and network planning. Higher order modulation formats increases the capacity of the link by their ability to encode data in both the phase and amplitude of light, thereby increasing the bits/sec/Hz as compared to simple on-off keyed format. Coherent communications has also emerged as a primary means of transmitting and receiving optical data due to its support of formats that utilize both phase and amplitude to further increase the spectral efficiency of the optical channel, including quadrature amplitude modulation (QAM) and quadrature phase shift keying (QPSK). Polarization multiplexing of channels can double capacity by allowing two channels to share the same wavelength by propagating on orthogonal polarization axis and is easily supported in coherent systems where the polarization tracking can be performed in the digital domain. Furthermore, the forthcoming IEEE 100 Gbit/s Ethernet Standard, 802.3ba, provides greater bandwidth, higher data rates, and supports a mixture of modulation formats. In particular, Pol-MUX QPSK is increasingly becoming the industry's format of choice as the high spectral efficiency allows for 100 Gbit/s transmission while still occupying the current 50 GHz/channel allocation of current 10 Gbit/s OOK fiber systems. In this manner, 100 Gbit/s transfer speeds using current fiber links, amplifiers, and filters

  4. Optical high-performance computing: introduction to the JOSA A and Applied Optics feature.

    PubMed

    Caulfield, H John; Dolev, Shlomi; Green, William M J

    2009-08-01

    The feature issues in both Applied Optics and the Journal of the Optical Society of America A focus on topics of immediate relevance to the community working in the area of optical high-performance computing.

  5. Active optics control development at the LBT

    NASA Astrophysics Data System (ADS)

    Ashby, David S.; Biddick, Christopher; Hill, John M.

    2014-07-01

    The Large Binocular Telescope (LBT) is built around two 8.4 m-diameter primary mirrors placed with a centerline separation of 14.4 m in a common altitude/azimuth mount. Each side of the telescope can utilize a deployable prime focus instrument; alternatively, the beam can be directed to a Gregorian instrument by utilizing a deployable secondary mirror. The direct-Gregorian beam can be intercepted and redirected to several bent-Gregorian instruments by utilizing a deployable tertiary mirror. Two of the available bent-Gregorian instruments are interferometers, capable of coherently combining the beams from the two sides of the telescope. Active optics can utilize as many as 26 linearly independent degrees of freedom to position the primary, secondary and tertiary mirrors to control optical collimation while the telescope operates in its numerous observing modes. Additionally, by applying differential forces at 160 locations on each primary mirror, active optics controls the primary mirror figure. The authors explore the challenges associated with collimation and primary mirror figure control at the LBT and outline the ongoing related development aimed at optimizing image quality and preparing the telescope for interferometric operations.

  6. A study of optical design for optics of high contrast projector

    NASA Astrophysics Data System (ADS)

    Yen, Chih-Ta; Fang, Yi-Chin; Tsai, Chen-Mu

    2011-10-01

    A new optical design inclusive of zoom optics and optical engine system is proposed in this paper. Traditionally, there is trade-off between F-number of projection optics and contrast, which seems that super high-contrast image from commercial projector was simply a dream. Some ideas of adaptive optics were announced before for the improvement of high contrast. However, few reach success or cost will be high. Traditionally, there is nothing to do with optics of projector and optical engine of projector if lens meets the specification. In this paper, a new optical design for optics and optical engine is studied with liquid optics arrays. Thanks to advanced optical design and LED light luminance, simulation results show that 50% improvement for image contrast could be made without sacrifice of volumetric size.

  7. Optical multichannel analyzer techniques for high resolution optical spectroscopy

    SciTech Connect

    Chao, J.L.

    1980-06-01

    The development of optical multichannel analyzer techniques for UV/VIS spectroscopy is presented. The research focuses on the development of spectroscopic techniques for measuring high resolution spectral lineshape functions from the exciton phosphorescence in H/sub 2/-1,2,4,5-tetrachlorobenzene. It is found that the temperature dependent frequency shifts and widths confirm a theoretical model based on an exchange theory. The exchange of low energy phonon modes which couple with excited state exciton transitions is shown to display the proper temperature dependent behavior. In addition to the techniques for using the optical multichannel analyzer (OMA) to perform low light level target integration, the use of the OMA for capturing spectral information in transient pulsed laser applications is discussed. An OMP data acquisition system developed for real-time signal processng is described. Both hardware and software interfacing considerations for control and data acquisition by a microcomputer are described. The OMA detector is described in terms of the principles behind its photoelectron detection capabilities and its design is compared with other optoelectronic devices.

  8. Low-cost active optical system for fire surveillance

    NASA Astrophysics Data System (ADS)

    Utkin, A. B.; Lavrov, A. V.; Vilar, R. M.

    2009-06-01

    Detection of smoke plumes using active optical sensors provides many advantages with respect to passive methods of fire surveillance. However, the price of these sensors is often too high as compared to passive fire detection instruments, such as infrared and video cameras. This article describes robust and cost effective diode-laser optical sensor for automatic fire surveillance in industrial environment. Physical aspects of the sensing process allowing to simplify the hardware and software design, eventually leading to significant reduction of manufacturing and maintenance costs, are discussed.

  9. Subtractive 3D printing of optically active diamond structures.

    PubMed

    Martin, Aiden A; Toth, Milos; Aharonovich, Igor

    2014-05-21

    Controlled fabrication of semiconductor nanostructures is an essential step in engineering of high performance photonic and optoelectronic devices. Diamond in particular has recently attracted considerable attention as a promising platform for quantum technologies, photonics and high resolution sensing applications. Here we demonstrate the fabrication of optically active, functional diamond structures using gas-mediated electron beam induced etching (EBIE). The technique achieves dry chemical etching at room temperature through the dissociation of surface-adsorbed H2O molecules by energetic electrons in a water vapor environment. Parallel processing is possible by electron flood exposure and the use of an etch mask, while high resolution, mask-free, iterative editing is demonstrated by direct write etching of inclined facets of diamond microparticles. The realized structures demonstrate the potential of EBIE for the fabrication of optically active structures in diamond.

  10. Towards green high capacity optical networks

    NASA Astrophysics Data System (ADS)

    Glesk, I.; Mohd Warip, M. N.; Idris, S. K.; Osadola, T. B.; Andonovic, I.

    2012-02-01

    The demand for fast, secure, energy efficient high capacity networks is growing. It is fuelled by transmission bandwidth needs which will support among other things the rapid penetration of multimedia applications empowering smart consumer electronics and E-businesses. All the above trigger unparallel needs for networking solutions which must offer not only high-speed low-cost "on demand" mobile connectivity but should be ecologically friendly and have low carbon footprint. The first answer to address the bandwidth needs was deployment of fibre optic technologies into transport networks. After this it became quickly obvious that the inferior electronic bandwidth (if compared to optical fiber) will further keep its upper hand on maximum implementable serial data rates. A new solution was found by introducing parallelism into data transport in the form of Wavelength Division Multiplexing (WDM) which has helped dramatically to improve aggregate throughput of optical networks. However with these advancements a new bottleneck has emerged at fibre endpoints where data routers must process the incoming and outgoing traffic. Here, even with the massive and power hungry electronic parallelism routers today (still relying upon bandwidth limiting electronics) do not offer needed processing speeds networks demands. In this paper we will discuss some novel unconventional approaches to address network scalability leading to energy savings via advance optical signal processing. We will also investigate energy savings based on advanced network management through nodes hibernation proposed for Optical IP networks. The hibernation reduces the network overall power consumption by forming virtual network reconfigurations through selective nodes groupings and by links segmentations and partitionings.

  11. Towards green high capacity optical networks

    NASA Astrophysics Data System (ADS)

    Glesk, I.; Mohd Warip, M. N.; Idris, S. K.; Osadola, T. B.; Andonovic, I.

    2011-09-01

    The demand for fast, secure, energy efficient high capacity networks is growing. It is fuelled by transmission bandwidth needs which will support among other things the rapid penetration of multimedia applications empowering smart consumer electronics and E-businesses. All the above trigger unparallel needs for networking solutions which must offer not only high-speed low-cost "on demand" mobile connectivity but should be ecologically friendly and have low carbon footprint. The first answer to address the bandwidth needs was deployment of fibre optic technologies into transport networks. After this it became quickly obvious that the inferior electronic bandwidth (if compared to optical fiber) will further keep its upper hand on maximum implementable serial data rates. A new solution was found by introducing parallelism into data transport in the form of Wavelength Division Multiplexing (WDM) which has helped dramatically to improve aggregate throughput of optical networks. However with these advancements a new bottleneck has emerged at fibre endpoints where data routers must process the incoming and outgoing traffic. Here, even with the massive and power hungry electronic parallelism routers today (still relying upon bandwidth limiting electronics) do not offer needed processing speeds networks demands. In this paper we will discuss some novel unconventional approaches to address network scalability leading to energy savings via advance optical signal processing. We will also investigate energy savings based on advanced network management through nodes hibernation proposed for Optical IP networks. The hibernation reduces the network overall power consumption by forming virtual network reconfigurations through selective nodes groupings and by links segmentations and partitionings.

  12. Active microstructured x-ray optical arrays

    NASA Astrophysics Data System (ADS)

    Michette, Alan G.; Pfauntsch, Slawka J.; Sahraei, Shahin; Shand, Matthew; Morrison, Graeme R.; Hart, David; Vojnovic, Boris; Stevenson, Tom; Parkes, William; Dunare, Camelia; Willingale, Richard; Feldman, Charlotte H.; Button, Tim W.; Zhang, Dou; Rodriguez-Sanmartin, Daniel; Wang, Hongchang; Smith, Andy D.

    2009-05-01

    The UK Smart X-Ray Optics consortium is developing novel reflective adaptive/active x-ray optics for small-scale laboratory applications, including studies of radiation-induced damage to biological material. The optics work on the same principle as polycapillaries, using configured arrays of channels etched into thin silicon, such that each x-ray photon reflects at most once off a channel wall. Using two arrays in succession provides two reflections and thus the Abbe sine condition can be approximately satisfied, reducing aberrations. Adaptivity is achieved by flexing one or both arrays using piezo actuation, which can provide further reduction of aberrations as well as controllable focal lengths. Modelling of such arrays for used on an x-ray microprobe, based on a microfocus source with an emitting region approximately 1μm in diameter, shows that a focused flux approximately two orders of magnitude greater than possible with a zone plate of comparable focal length is possible, assuming that the channel wall roughness is less than about 2nm.

  13. Optical activity and Alfred Werner's coordination chemistry.

    PubMed

    Ernst, Karl-Heinz; Berke, Heinz

    2011-03-01

    It is widely accepted, that Pasteur's seminal discovery of the opposite optical activity of ammonium sodium tartrate enantiomorphs in solution gave the spark to organic stereochemistry and led to the development of the tetrahedron model by van't Hoff and Le Bel. The proof that chirality is inherently connected to octahedral coordination chemistry fostered greatly Werner's spatial views of metal complexes and his coordination theory. The actual proof of principle was established via separation of diastereomeric camphor sulfonate salts of racemic metal complexes. PMID:20928897

  14. Vibrational Raman optical activity of biological molecules

    NASA Astrophysics Data System (ADS)

    Barron, L. D.; Gargaro, A. R.; Hecht, Lutz; Wen, Z. Q.; Hug, W.

    1991-05-01

    Advances in Raman optical activity (ROA) instrumentation based on the employment of a backscattering geometry together with a cooled CCD detector have now enhanced the sensitivity to the level necessary to provide vibrational ROA spectra of biological molecules in aqueous solution. Preliminary results on peptides and proteins show features originating in coupled Ca-H and N-H deformations of the peptide backbone which appear to be sensitive to the secondary conformation. Also carbohydrates show many features that appear to be characteristic of the central aspects of carbohydrate architecture with effects from the glycosidic link in di- and oligosaccharides particularly prominent. 1.

  15. Active microring based tunable optical power splitters

    NASA Astrophysics Data System (ADS)

    Peter, Eldhose; Thomas, Arun; Dhawan, Anuj; Sarangi, Smruti R.

    2016-01-01

    In this paper we propose a set of novel tunable optical power splitters based on active microring resonators. They work by operating ring resonators in the transient zone between full resonance and off-resonance states for a specific wavelength. We can achieve different split ratios by either varying the bias voltage, or by selectively enabling a given resonator with a specific split ratio among an array of ring resonators. We take 500 ps to tune the resonator, which is at least 10× better that competing designs. Its split ratio varies from 0.4 to 1.8 for an applied voltage range of 0-5 V.

  16. Optical Activity of Anisotropic Achiral Surfaces

    SciTech Connect

    Verbiest, T.; Kauranen, M.; Van Rompaey, Y.; Persoons, A. |

    1996-08-01

    Anisotropic achiral surfaces respond differently to left- and right-hand circularly polarized light. This occurs when the orientation of the surface with respect to an otherwise achiral experimental setup makes the total geometry chiral. Such optical activity is demonstrated in second-harmonic generation from an anisotropic thin molecular film. The circular-difference response reverses sign as the handedness of the geometry is reversed and vanishes when the setup possesses a mirror plane. The results are explained within the electric-dipole-allowed second-order surface nonlinearity. {copyright} {ital 1996 The American Physical Society.}

  17. Metal-Coated Optical Fibers for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Zeakes, Jason; Murphy, Kent; Claus, Richard; Greene, Jonathan; Tran, Tuan

    1996-01-01

    This poster will highlight on-going research at the Virginia Tech Fiber & Electro-Optics Research Center (FEORC) in the area of thin films on optical fibers. Topics will include the sputter deposition of metals and metal; alloys onto optical fiber and fiber optic sensors for innovative applications. Specific information will be available on thin film fiber optic hydrogen sensors, corrosion sensors, and metal-coated optical fiber for high temperature aerospace applications.

  18. Cooling solutions for high heat load optics

    SciTech Connect

    Morris, D.; Harding, G.H.; Cox, M.P.; Lunt, D.

    1996-09-01

    Heat loads on optical components at third-generation synchrotron sources, such as the APS, present beamline designers with difficult and complex engineering problems. A number of solutions have been proposed, such as pin-post water cooling, cryogenic cooling, and liquid gallium cooling. This paper describes both a cryogenic cooling system and a liquid gallium pumping system that have been developed specifically for the APS high heat load beamlines. Also presented is a potential solution for the first mirrors on high heat load beamlines, based on liquid gallium internal cooling of a silicon carbide mirror. {copyright} {ital 1996 American Institute of Physics.}

  19. Wide swath and high resolution optical imaging satellite of Japan

    NASA Astrophysics Data System (ADS)

    Katayama, Haruyoshi; Kato, Eri; Imai, Hiroko; Sagisaka, Masakazu

    2016-05-01

    The "Advanced optical satellite" (tentative name) is a follow-on mission from ALOS. Mission objectives of the advanced optical satellite is to build upon the existing advanced techniques for global land observation using optical sensors, as well as to promote data utilization for social needs. Wide swath and high resolution optical imager onboard the advanced optical satellite will extend the capabilities of earlier ALOS missions. The optical imager will be able to collect high-resolution (< 1 m) and wide-swath (70 km) images with high geo-location accuracy. This paper introduces a conceptual design of the advanced optical satellite.

  20. HIGH-EFFICIENCY AUTONOMOUS LASER ADAPTIVE OPTICS

    SciTech Connect

    Baranec, Christoph; Riddle, Reed; Tendulkar, Shriharsh; Hogstrom, Kristina; Bui, Khanh; Dekany, Richard; Kulkarni, Shrinivas; Law, Nicholas M.; Ramaprakash, A. N.; Burse, Mahesh; Chordia, Pravin; Das, Hillol; Punnadi, Sujit

    2014-07-20

    As new large-scale astronomical surveys greatly increase the number of objects targeted and discoveries made, the requirement for efficient follow-up observations is crucial. Adaptive optics imaging, which compensates for the image-blurring effects of Earth's turbulent atmosphere, is essential for these surveys, but the scarcity, complexity and high demand of current systems limit their availability for following up large numbers of targets. To address this need, we have engineered and implemented Robo-AO, a fully autonomous laser adaptive optics and imaging system that routinely images over 200 objects per night with an acuity 10 times sharper at visible wavelengths than typically possible from the ground. By greatly improving the angular resolution, sensitivity, and efficiency of 1-3 m class telescopes, we have eliminated a major obstacle in the follow-up of the discoveries from current and future large astronomical surveys.

  1. High precision Woelter optic calibration facility

    SciTech Connect

    Morales, R.I.; Remington, B.A.; Schwinn, T.

    1994-05-02

    We have developed an off-line facility for very precise characterization of the reflectance and spatial resolution of the grazing incidence Woelter Type 1 x-ray optics used at Nova. The primary component of the facility is a high brightness, ``point`` x-ray source consisting of a focussed DC electron beam incident onto a precision manipulated target/pinhole array. The data are recorded with a selection of detectors. For imaging measurements we use direct exposure x-ray film modules or an x-ray CCD camera. For energy-resolved reflectance measurements, we use lithium drifted silicon detectors and a proportional counter. An in situ laser alignment system allows precise location and rapid periodic alignment verification of the x-ray point source, the statically mounted Woelter optic, and the chosen detector.

  2. Active polarimeter optical system laser hazard analysis.

    SciTech Connect

    Augustoni, Arnold L.

    2005-07-01

    A laser hazard analysis was performed for the SNL Active Polarimeter Optical System based on the ANSI Standard Z136.1-2000, American National Standard for Safe Use of Lasers and the ANSI Standard Z136.6-2000, American National Standard for Safe Use of Lasers Outdoors. The Active Polarimeter Optical System (APOS) uses a pulsed, near-infrared, chromium doped lithium strontium aluminum fluoride (Cr:LiSAF) crystal laser in conjunction with a holographic diffuser and lens to illuminate a scene of interest. The APOS is intended for outdoor operations. The system is mounted on a height adjustable platform (6 feet to 40 feet) and sits atop a tripod that points the beam downward. The beam can be pointed from nadir to as much as 60 degrees off of nadir producing an illuminating spot geometry that can vary from circular (at nadir) to elliptical in shape (off of nadir). The JP Innovations crystal Cr:LiSAF laser parameters are presented in section II. The illuminating laser spot size is variable and can be adjusted by adjusting the separation distance between the lens and the holographic diffuser. The system is adjusted while platform is at the lowest level. The laser spot is adjusted for a particular spot size at a particular distance (elevation) from the laser by adjusting the separation distance (d{sub diffuser}) to predetermined values. The downward pointing angle is also adjusted before the platform is raised to the selected operation elevation.

  3. Neutron activation of NIF Final Optics Assemblies

    NASA Astrophysics Data System (ADS)

    Sitaraman, S.; Dauffy, L.; Khater, H.; Brereton, S.

    2010-08-01

    Analyses were performed to characterize the radiation field in the vicinity of the Final Optics Assemblies (FOAs) at the National Ignition Facility (NIF) due to neutron activation following Deuterium-Deuterium (DD), Tritium-Hydrogen-Deuterium (THD), and Deuterium-Tritium (DT) shots associated with different phases of the NIF operations. The activation of the structural components of the FOAs produces one of the larger sources of gamma radiation and is a key factor in determining the stay out time between shots to ensure worker protection. This study provides estimates of effective dose rates in the vicinity of a single FOA and concludes that the DD and THD targets produce acceptable dose rates within10 minutes following a shot while about 6-days of stay out time is suggested following DT shots. Studies are ongoing to determine the combined effects of multiple FOAs and other components present in the Target Bay on stay-out time and worker dose.

  4. Nanomechanics of Actively Controlled Deployable Optics

    NASA Technical Reports Server (NTRS)

    Peterson, Lee D.

    2000-01-01

    This document is the interim, annual report for the research grant entitled "Nanomechanics of Actively Controlled Deployed Optics." It is supported by NASA Langley Research Center Cooperative Agreement NCC-1 -281. Dr. Mark S. Lake is the technical monitor of the research program. This document reports activities for the year 1998, beginning 3/11/1998, and for the year 1999. The objective of this report is to summarize the results and the status of this research. This summary appears in Section 2.0. Complete details of the results of this research have been reported in several papers, publications and theses. Section 3.0 lists these publications and, when available, presents their abstracts. Each publication is available in electronic form from a web site identified in Section 3.0.

  5. Specialty fiber optic applications for harsh and high radiation environments

    NASA Astrophysics Data System (ADS)

    Risch, Brian G.

    2015-05-01

    Since the first commercial introduction in the 1980s, optical fiber technology has undergone an almost exponential growth. Currently over 2 billion fiber kilometers are deployed globally with 2014 global optical fiber production exceeding 300 million fiber kilometers. 1 Along with the staggering growth in optical fiber production and deployment, an increase in optical fiber technologies and applications has also followed. Although the main use of optical fibers by far has been for traditional data transmission and communications, numerous new applications are introduced each year. Initially the practical application of optical fibers was limited by cost and sensitivity of the optical fibers to stress, radiation, and other environmental factors. Tremendous advances have taken place in optical fiber design and materials allowing optical fibers to be deployed in increasingly harsh environments with exposure to increased mechanical and environmental stresses while maintaining high reliability. With the increased reliability, lower cost, and greatly expanded range of optical fiber types now available, new optical fiber deployments in harsh and high radiation environments is seeing a tremendous increase for data, communications, and sensing applications. An overview of key optical fiber applications in data, communications, and sensing for harsh environments in industrial, energy exploration, energy generation, energy transmission, and high radiation applications will be presented. Specific recent advances in new radiation resistant optical fiber types, other specialty optical fibers, optical fiber coatings, and optical fiber cable materials will be discussed to illustrate long term reliability for deployment of optical fibers in harsh and high radiation environments.

  6. Detecting eavesdropping activity in fiber optic networks

    NASA Astrophysics Data System (ADS)

    MacDonald, Gregory G.

    The secure transmission of data is critical to governments, military organizations, financial institutions, health care providers and other enterprises. The primary method of securing in-transit data is though data encryption. A number of encryption methods exist but the fundamental approach is to assume an eavesdropper has access to the encrypted message but does not have the computing capability to decrypt the message in a timely fashion. Essentially, the strength of security depends on the complexity of the encryption method and the resources available to the eavesdropper. The development of future technologies, most notably quantum computers and quantum computing, is often cited as a direct threat to traditional encryption schemes. It seems reasonable that additional effort should be placed on prohibiting the eavesdropper from coming into possession of the encrypted message in the first place. One strategy for denying possession of the encrypted message is to secure the physical layer of the communications path. Because the majority of transmitted information is over fiber-optic networks, it seems appropriate to consider ways of enhancing the integrity and security of the fiber-based physical layer. The purpose of this research is to investigate the properties of light, as they are manifested in single mode fiber, as a means of insuring the integrity and security of the physical layer of a fiber-optic based communication link. Specifically, the approach focuses on the behavior of polarization in single mode fiber, as it is shown to be especially sensitive to fiber geometry. Fiber geometry is necessarily modified during the placement of optical taps. The problem of detecting activity associated with the placement of an optical tap is herein approached as a supervised machine learning anomaly identification task. The inputs include raw polarization measurements along with additional features derived from various visualizations of the raw data (the inputs are

  7. Weak soft X-ray excesses need not result from the high-frequency tail of the optical/ultraviolet bump in active galactic nuclei

    NASA Technical Reports Server (NTRS)

    Czerny, Bozena; Zycki, Piotr T.

    1994-01-01

    The broad-band ROSAT/EXOSAT X-ray spectra of six Seyfert 1 galaxies are fitted by a model consisting of a direct power law and a component due to reflection/reprocessing from a partially ionized, optically thick medium. The reflected spectrum contains emission features from various elements in the soft X-ray range. In all objects but one (Mrk 335), the fit is satisfactory, and no additional soft X-ray excess is required by the data. This means that in most sources there is no need for the thermal 'big blue bumps' to extend into soft X-rays, and the soft X-ray excesses reported previously can be explained by reflection/reprocessing. Satisfactory fits are obtained for a medium ionized by a source radiating at less than or approximately 15% of the Eddington rate. The fits require that the reflection is enhanced relative to an isotropically emitting source above a flat disk. The necessary high effectiveness of reflection in the soft X-ray band requires strong soft thermal flux dominating over hard X-rays.

  8. High-speed wireless optical LANs

    NASA Astrophysics Data System (ADS)

    Oe, Kunishige; Sato, Syuichi; Okayama, Motoyuki; Kubota, Toshihiro

    2001-11-01

    Study on high speed indoor wireless optical LAN system enabling 100Mbps signal transmission with low bit error rate (10-9) is presented. To realize the optical LAN system handling 100 Mbps signal, a directed line of sight (LOS) system is adopted as the optical receiver sensitivity for a bit error rate of 10-9 for 100 Mbps signals is fairly large. In the system, new approaches are introduced: WDM technology which enables bi-directional transmission in full duplex manner is applied using a 1.3 micrometers laser diode for down-link and 0.65 micrometers red laser diode for up-link light sources. As the wavelengths of the two lasers are quite separated from each other, this WDM technology brings an advantage that two kind of semiconductor materials can be used for detectors; GaInAs is used for down-link while Si is applied for up-link. GaInAs PD cannot detect the up-link laser light of 0.65 micrometers and Si PD or APD cannot detect the down-link laser light of 1.3micrometers . Therefore full duplex transmission can be achieved in this configuration. In the indoor wireless optical LAN system, one of the critical points is the transmitter configuration for down- link which enables to deliver optical power enough for 100 Mbps transmission to user areas as wide as possible with inexpensive prices. To realize the point, a special 1.3micrometers laser diode, a spot-size converter integrated laser (SS-LD), is introduced in company with convex lens and an object lens to deliver optical power to areas as wide as possible. As the far-field patterns of the SS-LD are fairly narrow, most of the output power of the LD could be collected to and spread wide by the object lens of 40 magnifications. Using the device, 3m diameter circle area in the plane 2m apart from the 1.3micrometers SS-LD emitting 20 mW optical power, could receive optical power above the receiver sensitivity for a bit error rate of 10-9 for 100 Mbps signals. The visible red light is convenient for not only position

  9. High data rate optical transceiver terminal

    NASA Technical Reports Server (NTRS)

    Clarke, E. S.

    1973-01-01

    The objectives of this study were: (1) to design a 400 Mbps optical transceiver terminal to operate from a high-altitude balloon-borne platform in order to permit the quantitative evaluation of a space-qualifiable optical communications system design, (2) to design an atmospheric propagation experiment to operate in conjunction with the terminal to measure the degrading effects of the atmosphere on the links, and (3) to design typical optical communications experiments for space-borne laboratories in the 1980-1990 time frame. As a result of the study, a transceiver package has been configured for demonstration flights during late 1974. The transceiver contains a 400 Mbps transmitter, a 400 Mbps receiver, and acquisition and tracking receivers. The transmitter is a Nd:YAG, 200 Mhz, mode-locked, CW, diode-pumped laser operating at 1.06 um requiring 50 mW for 6 db margin. It will be designed to implement Pulse Quaternary Modulation (PQM). The 400 Mbps receiver utilizes a Dynamic Crossed-Field Photomultiplier (DCFP) detector. The acquisition receiver is a Quadrant Photomultiplier Tube (QPMT) and receives a 400 Mbps signal chopped at 0.1 Mhz.

  10. High performance optical wavelength multiplexer-demultiplexer.

    PubMed

    Dobrowolski, J A; Hara, E H; Sullivan, B T; Waldorf, A J

    1992-07-01

    The principle of an optical wavelength multiplexer-demultiplexer is described in which the signals undergo repeated reflections from special filter elements that can be designed for a wide range of cross-talk ratios. The insertion losses of these units can be quite small and they can be implemented to provide simultaneous multichannel two-way transmission. In a preliminary investigation of an experimental prototype an insertion loss of 0.5 dB and a cross talk of -35 dB were demonstrated. The multiplexer-demultiplexer is expected to have a long life and high reliability.

  11. Optical generation of narrowband high frequency ultrasound

    NASA Astrophysics Data System (ADS)

    Hung, Shi-Yao; Hsieh, Bao-Yu; Li, Pai-Chi

    2014-03-01

    We propose a multilayer film structure to generate high frequency and narrowband ultrasound. It consists of three light-absorbing layers and two light-transmittance layers. The amplitude is tunable by adjusting the optical absorption coefficient of light-absorbing layers. The delay can be adjusted by changing thicknesses of light-transmittance layers. In one example, the generated high frequency narrowband ultrasound signal has a center frequency of 18.4MHz and 32.6% fractional bandwidth using the proposed multilayer structure. Compared with this result, the single layer structure produces a center frequency of 20.2MHz and 125.7% fractional bandwidth. In addition, a single laser pulse was employed to generate US on the multilayer film as an US source and PA signals of the high optical absorption region of the phantom at the same time. Because the spectral characteristics of the ultrasound signals generated by the multi-layer film are tunable, it can be designed such that the US echo and PA echo are spectrally separable, thus enabling simultaneous US/PA imaging using only a single laser pulse. Feasibility of this proposed method was demonstrated by imaging of a cyst-like phantom.

  12. Hemodynamic responses to functional activation accessed by optical imaging

    NASA Astrophysics Data System (ADS)

    Ni, Songlin; Li, Pengcheng; Yang, Yuanyuan; Lv, Xiaohua; Luo, Qingming

    2006-01-01

    A multi-wavelength light-emitting diode (LED) and laser diode (LD) based optical imaging system was developed to visualize the changes in cerebral blood flow, oxygenation following functional activation simultaneously in rodent cortex. The 2-D blood flow image was accessed by laser speckle contrast imaging, and the spectroscopic imaging of intrinsic signal was used for the calculation of oxyhemoglobin (HbO), deoxyhemoglobin (Hb) and total hemoglobin (HbT) concentration. The combination of spectroscopic imaging and laser speckle contrast imaging provides the capability to simultaneously investigate the spatial and temporal blood flow and hemoglobin concentration changes with high resolution, which may lead to a better understanding of the coupling between neuronal activation and vascular responses. The optical imaging system been built is compact and convenient to investigators. And it is reliable to acquire raw data. In present study, the hemodynamic responses to cortical spreading depression (CSD) in parietal cortex of ~-chloralose/urethan anesthetized rats were demonstrated.

  13. Disulfide chromophore and its optical activity.

    PubMed

    Maloň, Petr; Bednárová, Lucie; Straka, Michal; Krejčí, Lucie; Kumprecht, Lukáš; Kraus, Tomáš; Kubáňová, Markéta; Baumruk, Vladimír

    2010-01-01

    The compounds I-IV derived from α-D-cyclodextrin moiety by bridging and/or interconnecting with various patterns of disulfide bonds were chosen as models for the spectroscopic study of conformation of the disulfide bridge. The energy gap between the disulfide and cyclodextrin's electronic transitions allows us to investigate absorption and electronic circular dichroism spectra without disturbing spectral overlaps with amides or aromatic amino acids in peptides or proteins. Raman optical activity (ROA) spectra were measured and the bands due to S-S and C-S stretching motion identified. Comparison with the quantum mechanical calculations of simple models indicates that sense of disulfide twist follows sign of the measured S-S ROA band.

  14. On life assessment of high reliability high power optical switch

    NASA Astrophysics Data System (ADS)

    Xu, Yuanjian; Chu, Peter

    2014-09-01

    High data rate and long range free space lasercom links require multi-watt optical transmitter power, which creates a need for high power redundancy switches to ensure high payload reliability. A high power optical switch (HPOS) with less than 0.15 dB loss and capable of switching more than 40 watts of optical power in a single mode fiber has been previously demonstrated in the Transformational Satellite Communication System program. Prototype switches, in either 1x2 or 2x2 configuration, have been subjected to pyro-shock test, vibration test, and vacuum operation. These switches showed no performance degradation as a result of these tests. Three prototypes went through 60,000 35-watt switching cycles and over 30 million low power switching cycles, and the switches showed no mechanical failure. The HPOS life is about 3.2 million switching cycles with a definition of 3-dB degradation in on/off extinction ratio, which is well suited for space applications.

  15. High-temperature, high-pressure optical cell

    NASA Technical Reports Server (NTRS)

    Harris, R. P. (Inventor); Holland, L. R. (Inventor); Smith, R. E. (Inventor)

    1986-01-01

    The invention is an optical cell for containment of chemicals under conditions of high temperature and high pressure. The cell is formed of a vitreous silica tube, two optical windows comprising a vitreous silica rod inserted into the ends of a tube, and fused into position in the tube ends. Windows are spaced apart to form a cavity enclosed by the tube and the windows. A hole is drilled radially through the tube and into the cavity. Another vitreous silica tube is fused to the silica tube around the hole to form the stem, which is perpendicular to the long axis of the tube. The open end of the stem is used to load chemicals into the cavity. Then the stem may be sealed, and if desired, it may be shortened in order to reduce the volume of the cavity, which extends into the stem.

  16. Optical alignment of high resolution Fourier transform spectrometers

    NASA Technical Reports Server (NTRS)

    Breckinridge, J. B.; Ocallaghan, F. G.; Cassie, A. G.

    1980-01-01

    Remote sensing, high resolution FTS instruments often contain three primary optical subsystems: Fore-Optics, Interferometer Optics, and Post, or Detector Optics. We discuss the alignment of a double-pass FTS containing a cat's-eye retro-reflector. Also, the alignment of fore-optics containing confocal paraboloids with a reflecting field stop which relays a field image onto a camera is discussed.

  17. High resolution wavefront measurement of aspheric optics

    NASA Astrophysics Data System (ADS)

    Erichsen, I.; Krey, S.; Heinisch, J.; Ruprecht, A.; Dumitrescu, E.

    2008-08-01

    With the recently emerged large volume production of miniature aspheric lenses for a wide range of applications, a new fast fully automatic high resolution wavefront measurement instrument has been developed. The Shack-Hartmann based system with reproducibility better than 0.05 waves is able to measure highly aspheric optics and allows for real time comparison with design data. Integrated advanced analysis tools such as calculation of Zernike coefficients, 2D-Modulation Transfer Function (MTF), Point Spread Function (PSF), Strehl-Ratio and the measurement of effective focal length (EFL) as well as flange focal length (FFL) allow for the direct verification of lens properties and can be used in a development as well as in a production environment.

  18. High-Throughput Nonlinear Optical Microscopy

    PubMed Central

    So, Peter T.C.; Yew, Elijah Y.S.; Rowlands, Christopher

    2013-01-01

    High-resolution microscopy methods based on different nonlinear optical (NLO) contrast mechanisms are finding numerous applications in biology and medicine. While the basic implementations of these microscopy methods are relatively mature, an important direction of continuing technological innovation lies in improving the throughput of these systems. Throughput improvement is expected to be important for studying fast kinetic processes, for enabling clinical diagnosis and treatment, and for extending the field of image informatics. This review will provide an overview of the fundamental limitations on NLO microscopy throughput. We will further cover several important classes of high-throughput NLO microscope designs with discussions on their strengths and weaknesses and their key biomedical applications. Finally, this review will close with a perspective of potential future technological improvements in this field. PMID:24359736

  19. Highly stretchable, printable nanowire array optical polarizers.

    PubMed

    Kwon, Soonshin; Lu, Dylan; Sun, Zhelin; Xiang, Jie; Liu, Zhaowei

    2016-09-21

    Designing optical components such as polarizers on substrates with high mechanical deformability have potential to realize new device platforms in photonics, wearable electronics, and sensors. Conventional manufacturing approaches that rely highly on top-down lithography, deposition and the etching process can easily confront compatibility issues and high fabrication complexity. Therefore, an alternative integration scheme is necessary. Here, we demonstrate fabrication of highly flexible and stretchable wire grid polarizers (WGPs) by printing bottom-up grown Ge or Ge/Si core/shell nanowires (NWs) on device substrates in a highly dense and aligned fashion. The maximum contrast ratio of 104 between transverse electric (TE) and transverse magnetic (TM) fields and above 99% (maximum 99.7%) of light blocking efficiency across the visible spectrum range are achieved. Further systematic analyses are performed both in experimental and numerical models to reveal the correspondence between physical factors (coverage ratio of NW arrays and diameter) and polarization efficiency. Moreover, we demonstrate distinctive merits of our approach: (i) high flexibility in the choice of substrates such as glass, plastic, or elastomer; (ii) easy combination with additional novel functionalities, for example, air permeability, flexibility/stretchability, biocompatibility, and a skin-like low mechanical modulus; (iii) selective printing of polarizers on a designated local area. PMID:27537105

  20. Highly stretchable, printable nanowire array optical polarizers.

    PubMed

    Kwon, Soonshin; Lu, Dylan; Sun, Zhelin; Xiang, Jie; Liu, Zhaowei

    2016-09-21

    Designing optical components such as polarizers on substrates with high mechanical deformability have potential to realize new device platforms in photonics, wearable electronics, and sensors. Conventional manufacturing approaches that rely highly on top-down lithography, deposition and the etching process can easily confront compatibility issues and high fabrication complexity. Therefore, an alternative integration scheme is necessary. Here, we demonstrate fabrication of highly flexible and stretchable wire grid polarizers (WGPs) by printing bottom-up grown Ge or Ge/Si core/shell nanowires (NWs) on device substrates in a highly dense and aligned fashion. The maximum contrast ratio of 104 between transverse electric (TE) and transverse magnetic (TM) fields and above 99% (maximum 99.7%) of light blocking efficiency across the visible spectrum range are achieved. Further systematic analyses are performed both in experimental and numerical models to reveal the correspondence between physical factors (coverage ratio of NW arrays and diameter) and polarization efficiency. Moreover, we demonstrate distinctive merits of our approach: (i) high flexibility in the choice of substrates such as glass, plastic, or elastomer; (ii) easy combination with additional novel functionalities, for example, air permeability, flexibility/stretchability, biocompatibility, and a skin-like low mechanical modulus; (iii) selective printing of polarizers on a designated local area.

  1. Thermal/structural/optical integrated design for optical window of a high-speed aerial optical camera

    NASA Astrophysics Data System (ADS)

    Zhang, Gaopeng; Yang, Hongtao; Mei, Chao; Shi, Kui; Wu, Dengshan; Qiao, Mingrui

    2015-10-01

    In order to obtain high quality image of the aero optical remote sensor, it is important to analysis its thermal-optical performance on the condition of high speed and high altitude. Especially for the key imaging assembly, such as optical window, the temperature variation and temperature gradient can result in defocus and aberrations in optical system, which will lead to the poor quality image. In order to improve the optical performance of a high speed aerial camera optical window, the thermal/structural/optical integrated design method is developed. Firstly, the flight environment of optical window is analyzed. Based on the theory of aerodynamics and heat transfer, the convection heat transfer coefficient is calculated. The temperature distributing of optical window is simulated by the finite element analysis software. The maximum difference in temperature of the inside and outside of optical window is obtained. Then the deformation of optical window under the boundary condition of the maximum difference in temperature is calculated. The optical window surface deformation is fitted in Zernike polynomial as the interface, the calculated Zernike fitting coefficients is brought in and analyzed by CodeV Optical Software. At last, the transfer function diagrams of the optical system on temperature field are comparatively analyzed. By comparing and analyzing the result, it can be obtained that the optical path difference caused by thermal deformation of the optical window is 149.6 nm, which is under PV <=1 4λ .The simulation result meets the requirements of optical design very well. The above study can be used as an important reference for other optical window designs.

  2. Extrinsic chirality: Tunable optically active reflectors and perfect absorbers

    NASA Astrophysics Data System (ADS)

    Plum, Eric

    2016-06-01

    Conventional three-dimensional (3D) chiral media can exhibit optical activity for transmitted waves, but optical activity for reflected waves is negligible. This work shows that mirror asymmetry of the experimental arrangement—extrinsic 3D chirality—leads to giant optical activity for reflected waves with fundamentally different characteristics. It is demonstrated experimentally that extrinsically 3D-chiral illumination of a lossy metasurface backed by a mirror enables tunable circular dichroism and circular birefringence as well as perfect absorption of circularly polarized waves. In contrast, such polarization phenomena vanish for conventional optically active media backed by a mirror.

  3. Natural optical design concepts for highly miniaturized camera systems

    NASA Astrophysics Data System (ADS)

    Voelkel, Reinhard

    1999-08-01

    Microcameras for computers, mobile phones, watches, security system and credit cards is a very promising future market. Semiconductor industry is now able to integrate light reception, signal amplification and processing in a low- power-consuming microchip of a few mm2 size. Active pixel sensors supply each pixel in an image sensor with an individually programmable functionality. Beside the electronic receptor chip, a highly miniaturized lens system is required. Compared to the progress in microelectronics, optics has not yet made a significant step. Today's microcamera lenses are usually a downscaled version of a classical lens system and rarely smaller than 3 mm X 3 mm X 3 mm. This lagging of optics is quite surprising. Biologists have systematically studied all types of natural eye sensors since the 18th Century. Mother Nature provides a variety of highly effective examples for miniaturized imaging system. Single-aperture systems are the appropriate solution if the size is a free design parameter. If the budget is tight and optics limited to size, nature prefers multiple-aperture systems, the so-called compound eyes. As compound eyes are limited in resolution and night view, a cluster of single-aperture eyes, as jumping spiders use, is probably a better solution. The recent development in micro- optics offers the chance to imitate such natural design concepts. We have investigated miniaturized imaging systems based on microlens array and natural optical design concepts. Practical limitations for system design, packaging and assembling are given. Examples for micro-optical components and imaging systems are presented.

  4. High pressure fiber optic sensor system

    DOEpatents

    Guida, Renato; Xia, Hua; Lee, Boon K; Dekate, Sachin N

    2013-11-26

    The present application provides a fiber optic sensor system. The fiber optic sensor system may include a small diameter bellows, a large diameter bellows, and a fiber optic pressure sensor attached to the small diameter bellows. Contraction of the large diameter bellows under an applied pressure may cause the small diameter bellows to expand such that the fiber optic pressure sensor may measure the applied pressure.

  5. Optical Assessment of Caries Lesion Structure and Activity

    NASA Astrophysics Data System (ADS)

    Lee, Robert Chulsung

    New, more sophisticated diagnostic tools are needed for the detection and characterization of caries lesions in the early stages of development. It is not sufficient to simply detect caries lesions, methods are needed to assess the activity of the lesion and determine if chemical or surgical intervention is needed. Previous studies have demonstrated that polarization sensitive optical coherence tomography (PS-OCT) can be used to nondestructively image the subsurface lesion structure and measure the thickness of the highly mineralized surface zone. Other studies have demonstrated that the rate of dehydration can be correlated with the lesion activity and that the rate can be measured using optical methods. The main objective of this work was to test the hypothesis that optical methods can be used to assess lesion activity on tooth coronal and root surfaces. Simulated caries models were used to develop and validate an algorithm for detecting and measuring the highly mineralized surface layer using PS-OCT. This work confirmed that the algorithm was capable of estimating the thickness of the highly mineralized surface layer with high accuracy. Near-infrared (NIR) reflectance and thermal imaging methods were used to assess activity of caries lesions by measuring the state of lesion hydration. NIR reflectance imaging performed the best for artificial enamel and natural coronal caries lesion samples, particularly at wavelengths coincident with the water absorption band at 1460-nm. However, thermal imaging performed the best for artificial dentin and natural root caries lesion samples. These novel optical methods outperformed the conventional methods (ICDAS II) in accurately assessing lesion activity of natural coronal and root caries lesions. Infrared-based imaging methods have shown potential for in-vivo applications to objectively assess caries lesion activity in a single examination. It is likely that if future clinical trials are a success, this novel imaging

  6. Enzymatic aerobic ring rearrangement of optically active furylcarbinols.

    PubMed

    Thiel, Daniel; Doknić, Diana; Deska, Jan

    2014-01-01

    Biogenic furans are currently discussed as highly attractive alternative feedstock in a post-fossil society; thus, also the creation of sustainable furan valorization pathways appears of great importance. Here an artificial Achmatowicz monooxygenase activity for the aerobic ring expansion of furans is achieved by the combination of commercial glucose oxidase as oxygen-activating biocatalyst and wild-type chloroperoxidase as oxygen-transfer mediator, providing a biological ready-to-use solution for this truly synthetic furan rearrangement. In concert with enzymatic transformations for the enantioselective preparation of optically active furylcarbinols, purely biocatalytic reaction cascades for the stereocontrolled construction of complex pyranones are obtained, exhibiting high functional group tolerance even to oxidation-sensitive moieties. PMID:25335580

  7. Electro-optic high voltage sensor

    DOEpatents

    Davidson, James R.; Seifert, Gary D.

    2003-09-16

    A small sized electro-optic voltage sensor capable of accurate measurement of high voltages without contact with a conductor or voltage source is provided. When placed in the presence of an electric field, the sensor receives an input beam of electromagnetic radiation. A polarization beam displacer separates the input beam into two beams with orthogonal linear polarizations and causes one linearly polarized beam to impinge a crystal at a desired angle independent of temperature. The Pockels effect elliptically polarizes the beam as it travels through the crystal. A reflector redirects the beam back through the crystal and the beam displacer. On the return path, the polarization beam displacer separates the elliptically polarized beam into two output beams of orthogonal linear polarization. The system may include a detector for converting the output beams into electrical signals and a signal processor for determining the voltage based on an analysis of the output beams.

  8. Polarization ray tracing in anisotropic optically active media

    NASA Technical Reports Server (NTRS)

    Mcclain, Stephen C.; Chipman, Russell A.

    1992-01-01

    Procedures for performing polarization ray tracing through birefringent media are presented in a form compatible with the standard methods of geometric ray tracing. The birefringent materials treated include the following: anisotropic optically active materials such as quartz, non-optically active uniaxial materials such as calcite, and isotropic optically active materials such as mercury sulfide or organic liquids. Refraction and reflection algorithms are presented which compute both ray directions and wave directions. Methods for computing polarization modes, refractive indices, optical path lengths, and Fresnel transmission and reflection coefficients are also specified.

  9. Terahertz chiral metamaterials with giant and dynamically tunable optical activity

    SciTech Connect

    Zhou, Jiangfeng; Chowdhury, Dibakar Roy; Zhao, Rongkuo; Azad, Abul K.; Chen, Hou-Tong; Soukoulis, Costas M.; Taylor, Antoinette J.; O'Hara, John F.

    2012-07-27

    We demonstrated giant optical activity using a chiral metamaterial composed of an array of conjugated bilayer metal structures. The chiral metamaterials were further integrated with photoactive inclusions to accomplish a wide tuning range of the optical activity through illumination with near-infrared light. The strong chirality observed in our metamaterials results in a negative refractive index, which can also be well controlled by the near-infrared optical excitation.

  10. Active Learning Environment with Lenses in Geometric Optics

    ERIC Educational Resources Information Center

    Tural, Güner

    2015-01-01

    Geometric optics is one of the difficult topics for students within physics discipline. Students learn better via student-centered active learning environments than the teacher-centered learning environments. So this study aimed to present a guide for middle school teachers to teach lenses in geometric optics via active learning environment…

  11. Fiber optic chemical microsensors employing optically active silica microspheres

    NASA Astrophysics Data System (ADS)

    Pope, Edward J. A.

    1995-05-01

    Dye-doped porous silica microspheres can be prepared from liquid solution at temperatures near ambient. Microsphere diameter can be controlled between approximately 5.0 microns to in excess of a millimeter. The resulting microspheres can be attached to the distal end of an optical fiber in which the proximal end is attached to a spectrophotometer. Depending upon the organic species doped into the microsphere, a wide variety of sensing functions are possible. In this paper, the use of microsensors for measuring pH, temperature, and solvent content of aqueous solutions is demonstrated. Potential utility of this type of sensor to heavy metals detection and biomedical diagnostics is also discussed.

  12. Electro-optic high voltage sensor

    DOEpatents

    Davidson, James R.; Seifert, Gary D.

    2002-01-01

    A small sized electro-optic voltage sensor capable of accurate measurement of high levels of voltages without contact with a conductor or voltage source is provided. When placed in the presence of an electric field, the sensor receives an input beam of electromagnetic radiation into the sensor. A polarization beam displacer serves as a filter to separate the input beam into two beams with orthogonal linear polarizations. The beam displacer is oriented in such a way as to rotate the linearly polarized beams such that they enter a Pockels crystal having at a preferred angle of 45 degrees. The beam displacer is therefore capable of causing a linearly polarized beam to impinge a crystal at a desired angle independent of temperature. The Pockels electro-optic effect induces a differential phase shift on the major and minor axes of the input beam as it travels through the Pockels crystal, which causes the input beam to be elliptically polarized. A reflecting prism redirects the beam back through the crystal and the beam displacer. On the return path, the polarization beam displacer separates the elliptically polarized beam into two output beams of orthogonal linear polarization representing the major and minor axes. The system may include a detector for converting the output beams into electrical signals, and a signal processor for determining the voltage based on an analysis of the output beams. The output beams are amplitude modulated by the frequency of the electric field and the amplitude of the output beams is proportional to the magnitude of the electric field, which is related to the voltage being measured.

  13. High resolution fiber optic interferometer: FY94 final report

    SciTech Connect

    Baldwin, D.P.; Zamzow, D.S.; D`Silva, A.P.

    1994-12-31

    Objective is a field, on-line high resolution spectrometer system capable of resolving the optical emission from actinide isotopes in an inductively coupled plasma. AOTF (acousto-optic tunable filter) and FFP (fiber optic Fabry-Perot) were combined in this spectrometer, using bulk optical materials. The AOTF-FFP system was tested on U-235/U-238 and RCRA metals. Future development is described; a commercialization plan is attached.

  14. Informal Activities with Lasers, Lights, and Lenses: The Hands-On Optics Project

    NASA Astrophysics Data System (ADS)

    Pompea, S. M.; Sparks, C. E.; Sparks, R. T.

    2005-12-01

    The Hands-On Optics project began as a follow-up to the 2001 NSF planning grant "Optics Education -- A Blueprint for the 21st Century", which described the value of informal science programs in addressing the disconnect between the ubiquity of optics in everyday life and the noticeable absence of optics education in K-12 curricula and in informal science education programs. Key partners in the project are NOAO, SPIE-The International Society for Optical Engineering, and the Optical Society of America (OSA). The informal instructional materials created by the project are distributed through science centers nationwide and through the Mathematics, Engineering, Science Achievement Program (MESA) in a number of states, including Arizona, California, Washington, and Maryland. A key part of the project is the involvement, modeled after Project ASTRO, of optics professionals currently engaged in outreach activities and programs. Optics professionals (termed optics resource volunteers) are teamed with MESA and science center educators in implementing the program. These hands-on, high-interest, standards-connected activities and materials provide 6, three-hour-long optics activity modules that can be used in a variety of informal settings. We will describe the techniques used at NOAO to train educators, parents, and optics professionals who will work with the HOO activities as well as the different approaches needed for different informal education programs, ranging from Saturday programs, after-school programs, and science center programs. NOAO is developing the six modules and associated kits as well as competitions that have broad appeal to 12-year olds. Hands-On Optics: Making an Impact with Light (HOO) is a collaborative NSF-funded four-year informal science education program to excite students about science by actively engaging them in optics activities. NOAO is operated by the Association of Universities for Research in Astronomy (AURA), Inc. under cooperative

  15. CCD-based optical CT scanning of highly attenuating phantoms

    NASA Astrophysics Data System (ADS)

    Al-Nowais, Shamsa; Doran, Simon J.

    2009-05-01

    The introduction of optical computed tomography (optical-CT) offers economic and easy to use 3-D optical readout for gel dosimeters. However, previous authors have noted some challenges regarding the accuracy of such imaging techniques at high values of optical density. In this paper, we take a closer look at the 'cupping' artefact evident in both light-scattering polymer systems and highly light absorbing phantoms using our CCD-based optical scanner. In addition, a technique is implemented whereby the maximum measurable optical absorbance is extended to correct for any errors that may have occurred in the estimated value of the dark current or ambient light reaching the detector. The results indicate that for absorbance values up to 2.0, the optical scanner results have good accuracy, whereas this is not the case at high absorbance values for reasons yet to be explained.

  16. TOCUSO: Test of Conceptual Understanding on High School Optics Topics

    ERIC Educational Resources Information Center

    Akarsu, Bayram

    2012-01-01

    Physics educators around the world often need reliable diagnostic materials to measure students' understanding of physics concept in high school. The purpose of this study is to evaluate a new diagnostic tool on High School Optics concept. Test of Conceptual Understanding on High School Optics (TOCUSO) consists of 25 conceptual items that…

  17. A new generation active arrays for optical flexibility in astronomical instrumentation

    NASA Astrophysics Data System (ADS)

    Kroes, G.; Jaskó, A.; Pragt, J. H.; Venema, L.; De Haan, M.

    2012-09-01

    Throughout the history of telescopes and astronomical instrumentation, new ways were found to open up unexplored possibilities in fundamental astronomical research by increasing the telescope size and instrumentation complexity. The ever demanding requirements on instrument performance pushes instrument complexity to the edge. In order to take the next leap forward in instrument development the optical design freedom needs to be increased drastically. The use of more complex and more accurate optics allows for shorter optical trains with smaller sizes, smaller number of components and reduced fabrication and alignment verification time and costs. Current optics fabrication is limited in surface form complexity and/or accuracy. Traditional active and adaptive optics lack the needed intrinsic long term stability and simplicity in design, manufacturing, verification and control. This paper explains how and why active arrays literally provide a flexible but stable basis for the next generation optical instruments. Combing active arrays with optically high quality face sheets more complex and accurate optical surface forms can be provided including extreme a-spherical (freeform) surfaces and thus allow for optical train optimization and even instrument reconfiguration. A zero based design strategy is adopted for the development of the active arrays addressing fundamental issues in opto-mechanical engineering. The various choices are investigated by prototypes and Finite Element Analysis. Finally an engineering concept will be presented following a highly stable adjustment strategy allowing simple verification and control. The Optimization metrology is described in an additional paper for this conference by T. Agócs et al.

  18. Donor-acceptor organo-imido polyoxometalates: high transparency, high activity redox-active NLO chromophores.

    PubMed

    Al-Yasari, Ahmed; Van Steerteghem, Nick; El Moll, Hani; Clays, Koen; Fielden, John

    2016-02-21

    We show that polyoxometalates (POMs) are an excellent redox-active acceptor on which to base high performance 2(nd) order non-linear optical (NLO) chromophores. This is demonstrated through three new organoimido-Lindqvist derivatives with HRS β0-values exceeding those of any dipolar organic system with comparable donor, π-system and absorption profile. Thus, organoimido POMs may provide a new generation of high performance, high transparency, and potentially redox-switchable NLO materials. PMID:26815652

  19. Donor-acceptor organo-imido polyoxometalates: high transparency, high activity redox-active NLO chromophores.

    PubMed

    Al-Yasari, Ahmed; Van Steerteghem, Nick; El Moll, Hani; Clays, Koen; Fielden, John

    2016-02-21

    We show that polyoxometalates (POMs) are an excellent redox-active acceptor on which to base high performance 2(nd) order non-linear optical (NLO) chromophores. This is demonstrated through three new organoimido-Lindqvist derivatives with HRS β0-values exceeding those of any dipolar organic system with comparable donor, π-system and absorption profile. Thus, organoimido POMs may provide a new generation of high performance, high transparency, and potentially redox-switchable NLO materials.

  20. Active learning in optics and photonics: Fraunhofer diffraction

    NASA Astrophysics Data System (ADS)

    Ghalila, H.; Ben Lakhdar, Z.; Lahmar, S.; Dhouaidi, Z.; Majdi, Y.

    2014-07-01

    "Active Learning in Optics and Photonics" (ALOP), funded by UNESCO within its Physics Program framework with the support of ICTP (Abdus Salam International Centre for Theoretical Physics) and SPIE (Society of Photo-Optical Instrumentation Engineers), aimed to helps and promotes a friendly and interactive method in teaching optics using simple and inexpensive equipment. Many workshops were organized since 2005 the year when Z. BenLakhdar, whom is part of the creators of ALOP, proposed this project to STO (Société Tunisienne d'Optique). These workshops address several issues in optics, covering geometrical optics, wave optics, optical communication and they are dedicated to both teachers and students. We focus this lecture on Fraunhofer diffraction emphasizing the facility to achieve this mechanism in classroom, using small laser and operating a slit in a sheet of paper. We accompany this demonstration using mobile phone and numerical modeling to assist in the analysis of the diffraction pattern figure.

  1. Optical impedance spectroscopy with single-mode electro-active-integrated optical waveguides.

    PubMed

    Han, Xue; Mendes, Sergio B

    2014-02-01

    An optical impedance spectroscopy (OIS) technique based on a single-mode electro-active-integrated optical waveguide (EA-IOW) was developed to investigate electron-transfer processes of redox adsorbates. A highly sensitive single-mode EA-IOW device was used to optically follow the time-dependent faradaic current originated from a submonolayer of cytochrome c undergoing redox exchanges driven by a harmonic modulation of the electric potential at several dc bias potentials and at several frequencies. To properly retrieve the faradaic current density from the ac-modulated optical signal, we introduce here a mathematical formalism that (i) accounts for intrinsic changes that invariably occur in the optical baseline of the EA-IOW device during potential modulation and (ii) provides accurate results for the electro-chemical parameters. We are able to optically reconstruct the faradaic current density profile against the dc bias potential in the working electrode, identify the formal potential, and determine the energy-width of the electron-transfer process. In addition, by combining the optically reconstructed faradaic signal with simple electrical measurements of impedance across the whole electrochemical cell and the capacitance of the electric double-layer, we are able to determine the time-constant connected to the redox reaction of the adsorbed protein assembly. For cytochrome c directly immobilized onto the indium tin oxide (ITO) surface, we measured a reaction rate constant of 26.5 s(-1). Finally, we calculate the charge-transfer resistance and pseudocapacitance associated with the electron-transfer process and show that the frequency dependence of the redox reaction of the protein submonolayer follows as expected the electrical equivalent of an RC-series admittance diagram. Above all, we show here that OIS with single-mode EA-IOW's provide strong analytical signals that can be readily monitored even for small surface-densities of species involved in the redox

  2. Application of portable optical laboratory in high schools and colleges

    NASA Astrophysics Data System (ADS)

    Altshuler, Gregory B.; Belashenkov, Nickolai R.; Ermolaev, Vladimir S.; Inochkin, Mickle V.; Karasev, Vyatcheslav B.

    1995-10-01

    The present paper describes the experience of application of portable optical laboratory in optical practicum developed directly for training and demonstrations of basic optical laws and phenomena in high-schools, colleges and nontechnical universities all over Russia. The laboratory includes the portable optical platform with built-in laser and lamp sources, kit of optical components and software. These accessories provide the attractive and smart teaching in general optics during lectures, lessons and practice at schools and colleges. The portable optical laboratory provides 28 basic lab works and demonstrations in reflection, refraction, absorption and dispersion of light, interference, diffraction, polarization of light, image formation and waveguide propagation of light in optical fibers. Due to their interdependence one can teach and learn a whole course of general optics. The individual work of students and school children with optical kit stimulates and develops their creative abilities and experimental skills, as well increases the effectiveness of education. The kit is provided with optional elements for a number of extra experiments with holography, polarizing light propagation, simple optical devices etc. These extensions allow to modify the education process according to teacher's point of view. The conception of optical class-room based on portable optical laboratories is discussed. The effectiveness of individual and small-group training is analyzed.

  3. (Bio)hybrid materials based on optically active particles

    NASA Astrophysics Data System (ADS)

    Reitzig, Manuela; Härtling, Thomas; Opitz, Jörg

    2014-03-01

    In this contribution we provide an overview of current investigations on optically active particles (nanodiamonds, upconversion phospors) for biohybrid and sensing applications. Due to their outstanding properties nanodiamonds gain attention in various application elds such as microelectronics, optical monitoring, medicine, and biotechnology. Beyond the typical diamond properties such as high thermal conductivity and extreme hardness, the carbon surface and its various functional groups enable diverse chemical and biological surface functionalization. At Fraunhofer IKTS-MD we develop a customization of material surfaces via integration of chemically modi ed nanodiamonds at variable surfaces, e.g bone implants and pipelines. For the rst purpose, nanodiamonds are covalently modi ed at their surface with amino or phosphate functionalities that are known to increase adhesion to bone or titanium alloys. The second type of surface is approached via mechanical implementation into coatings. Besides nanodiamonds, we also investigate the properties of upconversion phosphors. In our contribution we show how upconversion phosphors are used to verify sterilization processes via a change of optical properties due to sterilizing electron beam exposure.

  4. Using DFT Methods to Study Activators in Optical Materials

    SciTech Connect

    Du, Mao-Hua

    2015-08-17

    Density functional theory (DFT) calculations of various activators (ranging from transition metal ions, rare-earth ions, ns2 ions, to self-trapped and dopant-bound excitons) in phosphors and scintillators are reviewed. As a single-particle ground-state theory, DFT calculations cannot reproduce the experimentally observed optical spectra, which involve transitions between multi-electronic states. However, DFT calculations can generally provide sufficiently accurate structural relaxation and distinguish different hybridization strengths between an activator and its ligands in different host compounds. This is important because the activator-ligand interaction often governs the trends in luminescence properties in phosphors and scintillators, and can be used to search for new materials. DFT calculations of the electronic structure of the host compound and the positions of the activator levels relative to the host band edges in scintillators are also important for finding optimal host-activator combinations for high light yields and fast scintillation response. Mn4+ activated red phosphors, scintillators activated by Ce3+, Eu2+, Tl+, and excitons are shown as examples of using DFT calculations in phosphor and scintillator research.

  5. Using DFT Methods to Study Activators in Optical Materials

    DOE PAGES

    Du, Mao-Hua

    2015-08-17

    Density functional theory (DFT) calculations of various activators (ranging from transition metal ions, rare-earth ions, ns2 ions, to self-trapped and dopant-bound excitons) in phosphors and scintillators are reviewed. As a single-particle ground-state theory, DFT calculations cannot reproduce the experimentally observed optical spectra, which involve transitions between multi-electronic states. However, DFT calculations can generally provide sufficiently accurate structural relaxation and distinguish different hybridization strengths between an activator and its ligands in different host compounds. This is important because the activator-ligand interaction often governs the trends in luminescence properties in phosphors and scintillators, and can be used to search for new materials.more » DFT calculations of the electronic structure of the host compound and the positions of the activator levels relative to the host band edges in scintillators are also important for finding optimal host-activator combinations for high light yields and fast scintillation response. Mn4+ activated red phosphors, scintillators activated by Ce3+, Eu2+, Tl+, and excitons are shown as examples of using DFT calculations in phosphor and scintillator research.« less

  6. Active reflective components for adaptive optical zoom systems

    NASA Astrophysics Data System (ADS)

    Jungwirth, Matthew Edward Lewis

    This dissertation presents the theoretical and experimental exploration of active reflective components specifically for large-aperture adaptive optical zoom systems. An active reflective component can change its focal length by physically deforming its reflecting surface. Adaptive optical zoom (AOZ) utilizes active components in order to change magnification and achieve optical zoom, as opposed to traditional zooming systems that move elements along the optical axis. AOZ systems are theoretically examined using a novel optical design theory that enables a full-scale tradespace analysis, where optical design begins from a broad perspective and optimizes to a particular system. The theory applies existing strategies for telescope design and aberration simulation to AOZ, culminating in the design of a Cassegrain objective with a 3.3X zoom ratio and a 375mm entrance aperture. AOZ systems are experimentally examined with the development of a large-aperture active mirror constructed of a composite material called carbon fiber reinforced polymer (CFRP). The active CFRP mirror uses a novel actuation method to change radius of curvature, where actuators press against two annular rings placed on the mirror's back. This method enables the radius of curvature to increase from 2000mm to 2010mm. Closed-loop control maintains good optical performance of 1.05 waves peak-to-valley (with respect to a HeNe laser) when the active CFRP mirror is used in conjunction with a commercial deformable mirror.

  7. Photonic microwave receivers based on high-Q optical resonance

    NASA Astrophysics Data System (ADS)

    Hossein-Zadeh, Mani

    2012-02-01

    The quest for low power and high frequency electro-optical modulator has been one of the important endeavors in microwave photonics. The advent of microdisk electro-optic modulator created a new domain in optical modulator and photonic microwave receiver design by exploiting the unique properties of high quality (high-Q) Whispering-Gallery Mode (WGM) optical cavities. High-Q crystalline WG cavities were the first devices used as compact and low power resonant electro-optical modulators and gradually semiconductor and polymer based microdisk and microring modulators emerged from this core technology. Due to its small size, high sensitivity and limited bandwidth, originally microdisk modulator was developed with the objective of replacing the conventional microwave wireless receiver frontend with a sensitive photonic front-end. Later it was shown that the electro-optic microdisk modulator could also function as a microwave frequency mixer in optical domain. Starting from fundamentals of resonant electro-optic modulation in high-Q WGM cavities, in this paper we review the development of high sensitivity microdisk modulators and the recent progress toward more efficient modulation at higher frequencies. Next related topics such as singlesideband modulation, all-dielectric photonic receiver, and semiconductor microring modulators are briefly discussed. Finally, photonic microwave receiver configurations that employ high-Q optical resonance for modulation, filtering and mixing are presented. We will show that high-Q optical resonance is one of the promising routes toward the general idea of an all-optical microwave receiver free of high frequency electronic transistors, mixers and filters.

  8. Laser optical disk position encoder with active heads

    NASA Technical Reports Server (NTRS)

    Osborne, Eric P.

    1991-01-01

    An angular position encoder that minimizes the effects of eccentricity and other misalignments between the disk and the read stations by employing heads with beam steering optics that actively track the disk in directions along the disk radius and normal to its surface is discussed. The device adapts features prevalent in optical disk technology to the application of angular position sensing.

  9. Laser optical disk position encoder with active heads

    NASA Astrophysics Data System (ADS)

    Osborne, Eric P.

    An angular position encoder that minimizes the effects of eccentricity and other misalignments between the disk and the read stations by employing heads with beam steering optics that actively track the disk in directions along the disk radius and normal to its surface is discussed. The device adapts features prevalent in optical disk technology to the application of angular position sensing.

  10. Optical Properties of Anisotropic Polycrystalline Ce+3 activated LSO

    PubMed Central

    Roy, Sudesna; Lingertat, Helmut; Brecher, Charles; Sarin, Vinod

    2012-01-01

    Polycrystalline cerium activated lutetium oxyorthosilicate (LSO:Ce) is highly desirable technique to make cost effective and highly reproducible radiation detectors for medical imaging. In this article methods to improve transparency in polycrystalline LSO:Ce were explored. Two commercially available powders of different particulate sizes (average particle size 30 and 1500 nm) were evaluated for producing dense LSO:Ce by pressure assisted densification routes, such as hot pressing and hot isostatic pressing. Consolidation of the powders at optimum conditions produced three polycrystalline ceramics with average grain sizes of 500 nm, 700 and 2000 nm. Microstructural evolution studies showed that for grain sizes larger than 1 µm, anisotropy in thermal expansion coefficient and elastic constants of LSO, resulted in residual stress at grain boundaries and triple points that led to intragranular microcracking. However, reducing the grain size below 1 µm effectively avoids microcracking, leading to more favorable optical properties. The optical scattering profiles generated by a Stover scatterometer, measured by a He-Ne laser of wavelength 633 nm, showed that by reducing the grain size from 2 µm to 500 nm, the in-line transmission increased by a factor of 103. Although these values were encouraging and showed that small changes in grain size could increase transmission by almost 3 orders of magnitude, even smaller grain sizes need to be achieved in order to get truly transparent material with high in-line transmission. PMID:23505329

  11. Fiber optic chemical sensors: The evolution of high- density fiber-optic DNA microarrays

    NASA Astrophysics Data System (ADS)

    Ferguson, Jane A.

    2001-06-01

    Sensors were developed for multianalyte monitoring, fermentation monitoring, lactate analysis, remote oxygen detection for use in bioremediation monitoring and in a fuel spill clean-up project, heavy metal analysis, and high density DNA microarrays. The major focus of this thesis involved creating and improving high-density DNA gene arrays. Fiber optic sensors are created using fluorescent indicators, polymeric supports, and optical fiber substrates. The fluorescent indicator is entrapped in a polymer layer and attached to the tip of the optical fiber. The tip of the fiber bearing the sensing layer (the distal end) is placed in the sample of interest while the other end of the fiber (the proximal end) is connected to an analysis system. Any length of fiber can be used without compromising the integrity or sensitivity of the system. A fiber optic oxygen sensor was designed incorporating an oxygen sensitive fluorescent dye and a gas permeable polymer attached to an optical fiber. The construction simplicity and ruggedness of the sensor enabled its deployment for in situ chemical oxidation and bioremediation studies. Optical fibers were also used as the substrate to detect biomolecules in solution. To monitor bioprocesses, the production of the analyte of interest must be coupled with a species that is optically measurable. For example, oxygen is consumed in many metabolic functions. The fiber optic oxygen sensor is equipped with an additional sensing layer. Upon contact with a specific biochemical in the sample, a reaction occurs in the additional sensing layer that either consumes or produces oxygen. This dual layer system was used to monitor the presence of lactate, an important metabolite for clinical and bioprocess analysis. In many biological and environmental systems, the generation of one species occurs coincidentally with the generation or consumption of another species. A multianalyte sensor was prepared that can monitor the simultaneous activity of pH, CO2

  12. Lewis acid promoted highly diastereoselective Petasis Borono-Mannich reaction: efficient synthesis of optically active β,γ-unsaturated α-amino acids.

    PubMed

    Li, Yi; Xu, Ming-Hua

    2012-04-20

    An efficient and straightforward method for the preparation of highly enantiomerically enriched β,γ-unsaturated α-amino acid derivatives by a Lewis acid promoted diastereoselective Petasis reaction of vinylboronic acid, N-tert-butanesulfinamide, and glyoxylic acid has been developed. The synthetic utilities of the approach were demonstrated by the rapid and convenient construction of challenging cyclopenta[c]proline derivatives.

  13. Hybrid plasmonic lattices with tunable magneto-optical activity.

    PubMed

    Kataja, Mikko; Pourjamal, Sara; Maccaferri, Nicolò; Vavassori, Paolo; Hakala, Tommi K; Huttunen, Mikko J; Törmä, Päivi; van Dijken, Sebastiaan

    2016-02-22

    We report on the optical and magneto-optical response of hybrid plasmonic lattices that consist of pure nickel and gold nanoparticles in a checkerboard arrangement. Diffractive far-field coupling between the individual emitters of the lattices results in the excitation of two orthogonal surface lattice resonance modes. Local analyses of the radiation fields indicate that both the nickel and gold nanoparticles contribute to these collective resonances and, thereby, to the magneto-optical activity of the hybrid arrays. The strong effect of noble metal nanoparticles on the magneto-optical response of hybrid lattices opens up new avenues for the realization of sensitive and tunable magneto-plasmonic nanostructures. PMID:26907022

  14. Coherent phonon optics in a chip with an electrically controlled active device.

    PubMed

    Poyser, Caroline L; Akimov, Andrey V; Campion, Richard P; Kent, Anthony J

    2015-02-05

    Phonon optics concerns operations with high-frequency acoustic waves in solid media in a similar way to how traditional optics operates with the light beams (i.e. photons). Phonon optics experiments with coherent terahertz and sub-terahertz phonons promise a revolution in various technical applications related to high-frequency acoustics, imaging, and heat transport. Previously, phonon optics used passive methods for manipulations with propagating phonon beams that did not enable their external control. Here we fabricate a phononic chip, which includes a generator of coherent monochromatic phonons with frequency 378 GHz, a sensitive coherent phonon detector, and an active layer: a doped semiconductor superlattice, with electrical contacts, inserted into the phonon propagation path. In the experiments, we demonstrate the modulation of the coherent phonon flux by an external electrical bias applied to the active layer. Phonon optics using external control broadens the spectrum of prospective applications of phononics on the nanometer scale.

  15. Coherent phonon optics in a chip with an electrically controlled active device

    PubMed Central

    Poyser, Caroline L.; Akimov, Andrey V.; Campion, Richard P.; Kent, Anthony J.

    2015-01-01

    Phonon optics concerns operations with high-frequency acoustic waves in solid media in a similar way to how traditional optics operates with the light beams (i.e. photons). Phonon optics experiments with coherent terahertz and sub-terahertz phonons promise a revolution in various technical applications related to high-frequency acoustics, imaging, and heat transport. Previously, phonon optics used passive methods for manipulations with propagating phonon beams that did not enable their external control. Here we fabricate a phononic chip, which includes a generator of coherent monochromatic phonons with frequency 378 GHz, a sensitive coherent phonon detector, and an active layer: a doped semiconductor superlattice, with electrical contacts, inserted into the phonon propagation path. In the experiments, we demonstrate the modulation of the coherent phonon flux by an external electrical bias applied to the active layer. Phonon optics using external control broadens the spectrum of prospective applications of phononics on the nanometer scale. PMID:25652241

  16. Coherent phonon optics in a chip with an electrically controlled active device.

    PubMed

    Poyser, Caroline L; Akimov, Andrey V; Campion, Richard P; Kent, Anthony J

    2015-01-01

    Phonon optics concerns operations with high-frequency acoustic waves in solid media in a similar way to how traditional optics operates with the light beams (i.e. photons). Phonon optics experiments with coherent terahertz and sub-terahertz phonons promise a revolution in various technical applications related to high-frequency acoustics, imaging, and heat transport. Previously, phonon optics used passive methods for manipulations with propagating phonon beams that did not enable their external control. Here we fabricate a phononic chip, which includes a generator of coherent monochromatic phonons with frequency 378 GHz, a sensitive coherent phonon detector, and an active layer: a doped semiconductor superlattice, with electrical contacts, inserted into the phonon propagation path. In the experiments, we demonstrate the modulation of the coherent phonon flux by an external electrical bias applied to the active layer. Phonon optics using external control broadens the spectrum of prospective applications of phononics on the nanometer scale. PMID:25652241

  17. Optical activity of chitosan films with induced anisotropy

    NASA Astrophysics Data System (ADS)

    Gegel, Natalia O.; Shipovskaya, Anna B.

    2016-04-01

    The optical anisotropy and optical activity of salt and basic chitosan films, both initial and modified in formic acid vapor were studied. The modification of such films was found to be accompanied by induced time-stable optical anisotropy, by varying the values of specific optical rotation [α] and an inversion of the sign of [α]. The angular dependences (indicatrices) of the specific optical rotation of films on the orientation angle of the sample relative to the direction of the polarization vector of the incident light beam in a plane perpendicular to the beam were obtained. The indicatrices of the initial chitosan films have an almost symmetrical character while those of the films modified in formic acid vapor are irregular. It is concluded of the formation of a vitrified cholesteric mesophase in the chitosan films with induced optical anisotropy.

  18. Eurolaser. High power excimer laser: Optical crystals

    NASA Astrophysics Data System (ADS)

    Gaenswein, Bernhard

    1987-09-01

    The crystals used in excimer lasers because of their excellent optical properties in the ultra violet spectrum are described. The crystals are fluorides of the alkaline earth metals magnesium, calcium and barium and the alkaline fluorides of lithium and sodium. It is possible to grow optical monocrystals of these compounds up to weights of 15 kg with a diameter of 180 mm. Some problems develop in growing crystals larger than this. To do so greater plants and improved automatic temperature monitoring and regulation are required. Special tools are needed for handling such large and heavy monocrystals. Understanding of the interaction between laser radiation and crystal must be improved upon in order to meet all the requirements to be placed on optical components in the future.

  19. Active Learning Strategies for Introductory Light and Optics

    NASA Astrophysics Data System (ADS)

    Sokoloff, David R.

    2016-01-01

    There is considerable evidence that traditional approaches are ineffective in teaching physics concepts, including light and optics concepts. A major focus of the work of the Activity Based Physics Group has been on the development of active learning curricula like RealTime Physics (RTP) labs and Interactive Lecture Demonstrations (ILDs). Among the characteristics of these curricula are: (1) use of a learning cycle in which students are challenged to compare predictions—discussed with their peers in small groups—to observations of the physical world, (2) use of guided hands-on work to construct basic concepts from observations, and (3) use of computer-based tools. It has been possible to change the lecture and laboratory learning environments at a large number of universities, colleges, and high schools without changing the structure of the introductory course. For example, in the United States, nearly 200 physics departments have adopted RTP, and many others use pre-publication, open-source versions or have adopted the RTP approach to develop their own labs. Examples from RTP and ILDs (including optics magic tricks) are described in this paper.

  20. Optical properties of water at high temperature

    SciTech Connect

    French, Martin; Redmer, Ronald

    2011-04-15

    We calculate optical properties of water along the principal Hugoniot curve from ambient conditions up to temperatures of 130 000 K with density functional theory (DFT) and the Kubo-Greenwood formula. The effect of the exchange correlation functional is examined by comparing the generalized gradient approximation with a hybrid functional that contains Fock exchange. We find noticeable but moderate differences between the respective results which decrease rapidly above 80 000 K. The reflectivity along the principal Hugoniot is calculated and a good qualitative but fair quantitative agreement with available experimental data is found. Our results are of general relevance for calculations of optical properties with DFT at zero and elevated temperature.

  1. Nonlinear optical signal processing for high-speed, spectrally efficient fiber optic systems and networks

    NASA Astrophysics Data System (ADS)

    Zhang, Bo

    The past decade has witnessed astounding boom in telecommunication network traffic. With the emergence of multimedia over Internet, the high-capacity optical transport systems have started to shift focus from the core network towards the end users. This trend leads to diverse optical networks with transparency and reconfigurability requirement. As single channel data rate continues to increase and channel spacing continues to shrink for high capacity, high spectral efficiency, the workload on conventional electronic signal processing elements in the router nodes continues to build up. Performing signal processing functions in the optical domain can potentially alleviate the speed bottleneck if the unique optical properties are efficiently leveraged to assist electronic processing methodologies. Ultra-high bandwidth capability along with the promise for multi-channel and format-transparent operation make optical signal processing an attractive technology which is expected to have great impact on future optical networks. For optical signal processing applications in fiber-optic network and systems, a laudable goal would be to explore the unique nonlinear optical processes in novel photonic devices. This dissertation investigates novel optical signal processing techniques through simulations and experimental demonstrations, analyzes limitations of these nonlinear processing elements and proposes techniques to enhance the system performance or designs for functional photonic modules. Two key signal-processing building blocks for future optical networks, namely slow-light-based tunable optical delay lines and SOA-based high-speed wavelength converters, are presented in the first part of the dissertation. Phase preserving and spectrally efficient slow light are experimentally demonstrated using advanced modulation formats. Functional and novel photonic modules, such as multi-channel synchronizer and variable-bit-rate optical time division multiplexer are designed and

  2. 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.

  3. Bufferless Ultra-High Speed All-Optical Packet Routing

    NASA Astrophysics Data System (ADS)

    Muttagi, Shrihari; Prince, Shanthi

    2011-10-01

    All-Optical network is still in adolescence to cope up with steep rise in data traffic at the backbone network. Routing of packets in optical network depends on the processing speed of the All-Optical routers, thus there is a need to enhance optical processing to curb the delay in packet forwarding unit. In the proposed scheme, the header processing takes place on fly, therefore processing delay is at its lower limit. The objective is to propose a framework which establishes high data rate transmission with least latency in data routing from source to destination. The Routing table and optical header pulses are converted into Pulse Position (PP) format, thus reducing the complexity and in turn the processing delay. Optical pulse matching is exercised which results in multi-output transmission. This results in ultra-high speed packet forwarding unit. In addition, this proposed scheme includes dispersion compensation unit, which makes the data reliable.

  4. High-resolution retinal imaging using adaptive optics and Fourier-domain optical coherence tomography

    DOEpatents

    Olivier, Scot S.; Werner, John S.; Zawadzki, Robert J.; Laut, Sophie P.; Jones, Steven M.

    2010-09-07

    This invention permits retinal images to be acquired at high speed and with unprecedented resolution in three dimensions (4.times.4.times.6 .mu.m). The instrument achieves high lateral resolution by using adaptive optics to correct optical aberrations of the human eye in real time. High axial resolution and high speed are made possible by the use of Fourier-domain optical coherence tomography. Using this system, we have demonstrated the ability to image microscopic blood vessels and the cone photoreceptor mosaic.

  5. High energy laser optics manufacturing: a preliminary study

    SciTech Connect

    Baird, E.D.

    1980-07-01

    This report presents concepts and methods, major conclusions, and major recommendations concerning the fabrication of high energy laser optics (HELO) that are to be machined by the Large Optics Diamond Turning Machine (LODTM) at the Lawrence Livermore National Laboratory (LLNL). Detailed discussions of concepts and methods proposed for metrological operations, polishing of reflective surfaces, mounting of optical components, construction of mirror substrates, and applications of coatings are included.

  6. Diffraction-limited high-finesse optical cavities

    SciTech Connect

    Kleckner, Dustin; Irvine, William T. M.; Oemrawsingh, Sumant S. R.; Bouwmeester, Dirk

    2010-04-15

    High-quality optical cavities with wavelength-sized end mirrors are important to the growing field of micro-optomechanical systems. We present a versatile method for calculating the modes of diffraction limited optical cavities and show that it can be used to determine the effect of a wide variety of cavity geometries and imperfections. Additionally, we show these calculations agree remarkably well with FDTD simulations for wavelength-sized optical modes, even though our method is based on the paraxial approximation.

  7. The high education of optical engineering in East China

    NASA Astrophysics Data System (ADS)

    Liu, Xu; Liu, Xiangdong; Wang, Xiaoping; Bai, Jian; Liu, Yuling

    2014-07-01

    The history and the development of the high education in the field of optical engineering in the area of East China will be presented in the paper. The overall situation of research and human resource training in optics and photonics will also be reviewed, it shows that China needs lots of talents and experts in this field to support the world optical industry in East China.

  8. Optically triggered high voltage switch network and method for switching a high voltage

    DOEpatents

    El-Sharkawi, Mohamed A.; Andexler, George; Silberkleit, Lee I.

    1993-01-19

    An optically triggered solid state switch and method for switching a high voltage electrical current. A plurality of solid state switches (350) are connected in series for controlling electrical current flow between a compensation capacitor (112) and ground in a reactive power compensator (50, 50') that monitors the voltage and current flowing through each of three distribution lines (52a, 52b and 52c), which are supplying three-phase power to one or more inductive loads. An optical transmitter (100) controlled by the reactive power compensation system produces light pulses that are conveyed over optical fibers (102) to a switch driver (110') that includes a plurality of series connected optical triger circuits (288). Each of the optical trigger circuits controls a pair of the solid state switches and includes a plurality of series connected resistors (294, 326, 330, and 334) that equalize or balance the potential across the plurality of trigger circuits. The trigger circuits are connected to one of the distribution lines through a trigger capacitor (340). In each switch driver, the light signals activate a phototransistor (300) so that an electrical current flows from one of the energy reservoir capacitors through a pulse transformer (306) in the trigger circuit, producing gate signals that turn on the pair of serially connected solid state switches (350).

  9. Multicolour Optical Photometry of Active Geostationary Satellites

    NASA Astrophysics Data System (ADS)

    Jolley, A.; Wade, G.; Bedard, D.

    Although broadband photometry has been used to infer information about artificial satellites since soon after the launch of Sputnik 1, the development of photometric techniques for non-resolved space object identification or characterisation has been hampered by the large number of variables involved. Many individual studies, and some long ongoing experiments, have used costly metre-class telescopes to obtain data despite other experiments demonstrating that much more flexible and affordable small aperture telescopes may be suitable for the task. In addition, due to the highly time consuming and weather dependent nature of obtaining photometric observations, many studies have suffered from data sets of limited size, or relied upon simulations to support their claims. With this in mind, an experiment was conducted with the aim of determining the utility of small aperture telescopes for conducting broadband photometry of satellites for the purpose of non-resolved space object identification and characterisation. A 14 inch Celestron CG-14 telescope was used to gain multiple night-long, high temporal resolution data sets of six active geostationary satellites. The results of the experiment cast doubt on the efficacy of some of the previous approaches to obtaining and analysing photometric data. It was discovered that geostationary satellite lightcurves can vary to a greater degree than has generally been recognised, and colour ratios vary considerably with changes in the illumination/observation geometry, making it difficult to use colour for satellite discrimination. Evidence was also detected of variations in the spectral energy distribution of sunlight reflected off satellite surface materials, which could have implications for surface material characterisation and techniques that aim to separate satellite body and solar panel contributions to the total observed spectra.

  10. A Large Aperture, High Energy Laser System for Optics and Optical Component Testing

    SciTech Connect

    Nostrand, M C; Weiland, T L; Luthi, R L; Vickers, J L; Sell, W D; Stanley, J A; Honig, J; Auerbach, J; Hackel, R P; Wegner, P J

    2003-11-01

    A large aperture, kJ-class, multi-wavelength Nd-glass laser system has been constructed at Lawrence Livermore National Lab which has unique capabilities for studying a wide variety of optical phenomena. The master-oscillator, power-amplifier (MOPA) configuration of this ''Optical Sciences Laser'' (OSL) produces 1053 nm radiation with shaped pulse lengths which are variable from 0.1-100 ns. The output can be frequency doubled or tripled with high conversion efficiency with a resultant 100 cm{sup 2} high quality output beam. This facility can accommodate prototype hardware for large-scale inertial confinement fusion lasers allowing for investigation of integrated system issues such as optical lifetime at high fluence, optics contamination, compatibility of non-optical materials, and laser diagnostics.

  11. Photo-induced optical activity in phase-change memory materials.

    PubMed

    Borisenko, Konstantin B; Shanmugam, Janaki; Williams, Benjamin A O; Ewart, Paul; Gholipour, Behrad; Hewak, Daniel W; Hussain, Rohanah; Jávorfi, Tamás; Siligardi, Giuliano; Kirkland, Angus I

    2015-03-05

    We demonstrate that optical activity in amorphous isotropic thin films of pure Ge2Sb2Te5 and N-doped Ge2Sb2Te5N phase-change memory materials can be induced using rapid photo crystallisation with circularly polarised laser light. The new anisotropic phase transition has been confirmed by circular dichroism measurements. This opens up the possibility of controlled induction of optical activity at the nanosecond time scale for exploitation in a new generation of high-density optical memory, fast chiroptical switches and chiral metamaterials.

  12. High precision geometrical characterization and alignment of miniaturized optics

    NASA Astrophysics Data System (ADS)

    Langehanenberg, Patrik; Heinisch, Josef; Dumitrescu, Eugen

    2012-03-01

    Miniaturized optical systems like endoscopy or cell phone lenses systems comprise several optical elements like lenses, doublets and plane optics. To receive a good imaging quality the distances and angles between the different optical elements have to be as accurate as possible. In the first step we will describe how the distances and angles between different elements can be monitored and finally we will describe a technique to actively align small optics (diameter approx. 1mm and smaller) with respect to each other. For the measurement electronic autocollimators combined with white-light-interferometers are used. The electronic autocollimator reveals the exact centration errors between optical elements and the low coherence interferometer reveals the distances between surfaces. The accuracy of the centration error measurement is in the range of 0.1μm and the accuracy of the distance measurement is 1μm. Both methods can be applied to assembled multi-element optics. That means geometrical positions of all single surfaces of the final optical system can be analysed without loss of information. Both measurement techniques complement one another. Once the exact x,y,z - Position of each optical surface and element is known computer controlled actuators will be used to improve the alignment of the optics. For this purpose we use piezo-electric-actuators. This method had been applied to cement e.g. doublets for endoscope optics. In this case the optical axis of one lens has been aligned with respect to the optical axis of a second reference lens. Traditional techniques usually rely on an uncertain mechanical reference.

  13. Integrated compact optical current sensors with high sensitivity

    NASA Astrophysics Data System (ADS)

    Huang, Duanni; Pintus, Paolo; Srinivasan, Sudharsanan; Bowers, John E.

    2016-02-01

    We demonstrate a Sagnac based fiber optic current sensor using only 10cm of terbium doped fiber with a high Verdet constant of 15.5 rad/Tm at a wavelength of 1300nm. Measurements of the fiber inside a solenoid show over 40dB of open loop dynamic range as well as a minimum detectable current of 0.1mA. In order to decrease size while increasing sensitivity even further, we consider integrated magneto-optic waveguides as the sensing element. Using silicon waveguides alongside magneto-optic material such as cerium doped yttrium iron garnet (Ce:YiG), we model the Verdet constant to be as high as 10,000 rad/Tm. This improvement by three orders of magnitude shows potential for magnetooptic waveguides to be used in ultra-high sensitivity optical magnetometers and current sensors. Finally, we propose a fully integrated optical current sensor using heterogeneous integration for silicon photonics.

  14. Optical glass with tightest refractive index and dispersion tolerances for high-end optical designs

    NASA Astrophysics Data System (ADS)

    Jedamzik, R.; Reichel, S.; Hartmann, P.

    2014-03-01

    In high end optical designs the quality of the optical system not only depends on the chosen optical glasses but also on the available refractive index and Abbe number tolerances. The primary optical design is based on datasheet values of the refractive index and Abbe number. In general the optical position of the delivered glass will deviate from the catalog values by given tolerances due to production tolerances. Therefore in many cases the final optical design needs to be modified based on real glass data. Tighter refractive index and Abbe number tolerances can greatly reduce this additional amount of work. The refractive index and Abbe number of an optical glass is a function of the chemical composition and the annealing process. Tight refractive index tolerances require not only a close control and high reliability of the melting and fine annealing process but also best possible material data. These data rely on high accuracy measurement and accurate control during mass production. Modern melting and annealing procedure do not only enable tight index tolerances but also a high homogeneity of the optical properties. Recently SCHOTT was able to introduce the tightest available refractive index and Abbe number tolerance available in the market: step 0.5 meaning a refractive index tolerance of +/- 0.0001 and an Abbe number tolerance of +/- 0.1%. This presentation describes how the refractive index depends on the glass composition and annealing process and describes the requirements to get to this tightest refractive index and Abbe number tolerance.

  15. Highly efficient metallic optical incouplers for quantum well infrared photodetectors.

    PubMed

    Liu, Long; Chen, Yu; Huang, Zhong; Du, Wei; Zhan, Peng; Wang, Zhenlin

    2016-01-01

    Herein, we propose a highly efficient metallic optical incoupler for a quantum well infrared photodetector (QWIP) operating in the spectrum range of 14~16 μm, which consists of an array of metal micropatches and a periodically corrugated metallic back plate sandwiching a semiconductor active layer. By exploiting the excitations of microcavity modes and hybrid spoof surface plasmons (SSPs) modes, this optical incoupler can convert infrared radiation efficiently into the quantum wells (QWs) layer of semiconductor region with large electrical field component (Ez) normal to the plane of QWs. Our further numerical simulations for optimization indicate that by tuning microcavity mode to overlap with hybrid SSPs mode in spectrum, a coupled mode is formed, which leads to 33-fold enhanced light absorption for QWs centered at wavelength of 14.5 μm compared with isotropic absorption of QWs without any metallic microstructures, as well as a large value of coupling efficiency (η) of |Ez|(2) ~ 6. This coupled mode shows a slight dispersion over ~40° and weak polarization dependence, which is quite beneficial to the high performance infrared photodetectors. PMID:27456691

  16. Highly efficient metallic optical incouplers for quantum well infrared photodetectors

    NASA Astrophysics Data System (ADS)

    Liu, Long; Chen, Yu; Huang, Zhong; Du, Wei; Zhan, Peng; Wang, Zhenlin

    2016-07-01

    Herein, we propose a highly efficient metallic optical incoupler for a quantum well infrared photodetector (QWIP) operating in the spectrum range of 14~16 μm, which consists of an array of metal micropatches and a periodically corrugated metallic back plate sandwiching a semiconductor active layer. By exploiting the excitations of microcavity modes and hybrid spoof surface plasmons (SSPs) modes, this optical incoupler can convert infrared radiation efficiently into the quantum wells (QWs) layer of semiconductor region with large electrical field component (Ez) normal to the plane of QWs. Our further numerical simulations for optimization indicate that by tuning microcavity mode to overlap with hybrid SSPs mode in spectrum, a coupled mode is formed, which leads to 33-fold enhanced light absorption for QWs centered at wavelength of 14.5 μm compared with isotropic absorption of QWs without any metallic microstructures, as well as a large value of coupling efficiency (η) of |Ez|2 ~ 6. This coupled mode shows a slight dispersion over ~40° and weak polarization dependence, which is quite beneficial to the high performance infrared photodetectors.

  17. Highly efficient metallic optical incouplers for quantum well infrared photodetectors

    PubMed Central

    Liu, Long; Chen, Yu; Huang, Zhong; Du, Wei; Zhan, Peng; Wang, Zhenlin

    2016-01-01

    Herein, we propose a highly efficient metallic optical incoupler for a quantum well infrared photodetector (QWIP) operating in the spectrum range of 14~16 μm, which consists of an array of metal micropatches and a periodically corrugated metallic back plate sandwiching a semiconductor active layer. By exploiting the excitations of microcavity modes and hybrid spoof surface plasmons (SSPs) modes, this optical incoupler can convert infrared radiation efficiently into the quantum wells (QWs) layer of semiconductor region with large electrical field component (Ez) normal to the plane of QWs. Our further numerical simulations for optimization indicate that by tuning microcavity mode to overlap with hybrid SSPs mode in spectrum, a coupled mode is formed, which leads to 33-fold enhanced light absorption for QWs centered at wavelength of 14.5 μm compared with isotropic absorption of QWs without any metallic microstructures, as well as a large value of coupling efficiency (η) of |Ez|2 ~ 6. This coupled mode shows a slight dispersion over ~40° and weak polarization dependence, which is quite beneficial to the high performance infrared photodetectors. PMID:27456691

  18. Electro-optical time marker for high-speed cameras

    NASA Technical Reports Server (NTRS)

    Copeland, J. T., Jr.

    1970-01-01

    Electro-optical device converts high-frequency electrical pulses into permanent optical records on film. Accurate, well defined images are formed of electronic pulses having repetition rates greater than 10,000 pulses/sec and pulse widths of 20 microseconds or less. Small electronic switch drives a silicon carbide electroluminescent diode.

  19. Alternative high-resolution lithographic technologies for optical applications

    NASA Astrophysics Data System (ADS)

    Zeitner, Uwe D.; Weichelt, Tina; Bourgin, Yannick; Kinder, Robert

    2016-03-01

    Modern optical applications have special demands on the lithographic fabrication technologies. This relates to the lateral shape of the structures as well as to their three dimensional surface profile. On the other hand optical nano-structures are often periodic which allows for the use of dedicated lithographic exposure principles. The paper briefly reviews actual developments in the field of optical nano-structure generation. Special emphasis will be given to two technologies: electron-beam lithography based on a flexible cell-projection method and the actual developments in diffractive mask aligner lithography. Both offer a cost effective fabrication alternative for high resolution structures or three-dimensional optical surface profiles.

  20. Optical waveguides having flattened high order modes

    SciTech Connect

    Messerly, Michael Joseph; Beach, Raymond John; Heebner, John Edward; Dawson, Jay Walter; Pax, Paul Henry

    2014-08-05

    A deterministic methodology is provided for designing optical fibers that support field-flattened, ring-like higher order modes. The effective and group indices of its modes can be tuned by adjusting the widths of the guide's field-flattened layers or the average index of certain groups of layers. The approach outlined here provides a path to designing fibers that simultaneously have large mode areas and large separations between the propagation constants of its modes.

  1. Improved optical performance monitoring technique based on nonlinear optics for high-speed WDM Nyquist systems

    NASA Astrophysics Data System (ADS)

    Guesmi, Latifa; Menif, Mourad

    2016-04-01

    The field of fiber optics nonlinearity is more discussed last years due to such remarkable enhancement in the nonlinear processes efficiency. In this paper, and for optical performance monitoring (OPM), a new achievement of nonlinear effects has been investigated. The use of cross-phase modulation (XPM) and four-wave mixing (FWM) effects between input optical signal and inserted continuous-wave probe has proposed for impairments monitoring. Indeed, transmitting a multi-channels phase modulated signal at high data rate (1 Tbps WDM Nyquist NRZ- DP-QPSK) improves the sensitivity and the dynamic range monitoring. It was observed by simulation results that various optical parameters including optical power, wavelength, chromatic dispersion (CD), polarization mode dispersion (PMD), optical signal-to-noise ratio (OSNR), Q-factor and so on, can be monitored. Also, the effect of increasing the channel spacing between WDM signals is studied and proved its use for FWM power monitoring.

  2. Acoustic force mapping in a hybrid acoustic-optical micromanipulation device supporting high resolution optical imaging.

    PubMed

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

    2016-04-21

    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

  3. High-Speed Characterizatin of Optical Telecommunication Signals

    SciTech Connect

    Dorrer, C.

    2007-05-17

    Optical telecommunication systems constantly evolve toward higher bit rates, requiring the modulation and detection of higher-bandwidth optical waves. Commercial systems operating at 40 Gb/s are now available and research and development efforts are targeting higher bit rates for which optical pulses with picosecond-range duration are used. Chromatic dispersion, nonlinearities and amplified spontaneous emission from optical amplifiers are sources of transmission impairments that must be characterized and mitigated. Advanced modulation formats rely on the modulation of not only the amplitude of an optical wave (e.g., on/off keying), but also its phase (e.g., phase-shift keying) in order to optimize the transmission capabilities. The importance of the characterization of the properties of optical sources and components and the specificities of the optical telecommunication environment with respect to ultrafast optics are emphasized. Various diagnostics measuring the electric field of optical sources in the telecommunication environment are described. Sampling diagnostics capable of measuring eye diagrams and constellation diagrams of high-bit-rate, data-encoded sources are presented. Various optical pulse characterization techniques that meet the sensitivity requirements imposed by the telecommunication environment are also described.

  4. High Average Power Laser Gain Medium With Low Optical Distortion Using A Transverse Flowing Liquid Host

    DOEpatents

    Comaskey, Brian J.; Ault, Earl R.; Kuklo, Thomas C.

    2005-07-05

    A high average power, low optical distortion laser gain media is based on a flowing liquid media. A diode laser pumping device with tailored irradiance excites the laser active atom, ion or molecule within the liquid media. A laser active component of the liquid media exhibits energy storage times longer than or comparable to the thermal optical response time of the liquid. A circulation system that provides a closed loop for mixing and circulating the lasing liquid into and out of the optical cavity includes a pump, a diffuser, and a heat exchanger. A liquid flow gain cell includes flow straighteners and flow channel compression.

  5. Review of active optics methods in astronomy from x-rays to the infrared

    NASA Astrophysics Data System (ADS)

    Lemaitre, Gérard R.

    2010-09-01

    This review on Active Optics Methods presents various concepts of deformable uv, visible and ir telescope optics which have been mainly developed at the Marseille Observatory - for now 40 years - and other institutes. An optical surface generated by active optics and spherical figuring is free from high spatial frequency errors i.e. ripple errors. Active Optics allows applications of new concepts as: stress figuring aspherization processes, variable curvature mirrors, in situ stressing aspherization processes, under stress replications to generate corrected diffraction gratings, multimode deformable compensators, and situ control of large telescope optics. X-ray telescope mirrors could also benefit soon from the enhanced imaging performances of active optics. The 0.5- 1 arcsec spatial resolution of Chandra should be followed up by increased resolution space telescopes. This requires constructing new grazing-incidence telescopes which will strictly satisfy Abbe's sine condition, i.e. a Chase-VanSpeybroeck design for the two-mirror case. The recent elaboration of an elasticity theory of weakly conical shells allows reviewing some potential innovative concepts for the active figuring and in situ control of either monolithic or segmented telescope mirrors for x-ray astronomy.

  6. Label-free optical activation of astrocyte in vivo

    NASA Astrophysics Data System (ADS)

    Choi, Myunghwan; Yoon, Jonghee; Ku, Taeyun; Choi, Kyungsun; Choi, Chulhee

    2011-07-01

    As the most abundant cell type in the central nervous system, astrocyte has been one of main research topics in neuroscience. Although various tools have been developed, at present, there is no tool that allows noninvasive activation of astrocyte in vivo without genetic or pharmacological perturbation. Here we report a noninvasive label-free optical method for physiological astrocyte activation in vivo using a femtosecond pulsed laser. We showed the laser stimulation robustly induced astrocytic calcium activation in vivo and further verified physiological relevance of the calcium increase by demonstrating astrocyte mediated vasodilation in the brain. This novel optical method will facilitate noninvasive physiological study on astrocyte function.

  7. Active Learning Strategies for Introductory Light and Optics

    ERIC Educational Resources Information Center

    Sokoloff, David R.

    2016-01-01

    There is considerable evidence that traditional approaches are ineffective in teaching physics concepts, including light and optics concepts. A major focus of the work of the Activity Based Physics Group has been on the development of active learning curricula like RealTime Physics (RTP) labs and Interactive Lecture Demonstrations (ILDs). Among…

  8. Active stabilization of the optical part in fiber optic quantum cryptography

    NASA Astrophysics Data System (ADS)

    Balygin, K. A.; Klimov, A. N.; Kulik, S. P.; Molotkov, S. N.

    2016-03-01

    The method of active stabilization of the polarization and other parameters of the optical part of a two-pass fiber optic quantum cryptography has been proposed and implemented. The method allows the completely automated maintenance of the visibility of interference close to an ideal value ( V ≥ 0.99) and the reduction of the instrumental contribution to the error in primary keys (QBER) to 0.5%.

  9. Calculation of bending losses for highly confined modes of optical waveguides with transformation optics.

    PubMed

    Han, Zhanghua; Zhang, Pu; Bozhevolnyi, Sergey I

    2013-06-01

    We revisited the fundamental problem of bending loss calculation in optical waveguide theory using transformation optics (TOs). Due to the fact that TOs is based on the form invariance property of Maxwell equations, this new approach provides more accurate calculation of waveguide bending loss compared to the conventional refractive index conformal mapping method, especially for small bending radii typical for plasmonic waveguides or photonic waveguides with high-index contrast. We believe our results provide a simple yet reliable way of bending loss calculation for highly confined optical (including plasmonic) waveguides.

  10. Magneto-optical system for high speed real time imaging.

    PubMed

    Baziljevich, M; Barness, D; Sinvani, M; Perel, E; Shaulov, A; Yeshurun, Y

    2012-08-01

    A new magneto-optical system has been developed to expand the range of high speed real time magneto-optical imaging. A special source for the external magnetic field has also been designed, using a pump solenoid to rapidly excite the field coil. Together with careful modifications of the cryostat, to reduce eddy currents, ramping rates reaching 3000 T/s have been achieved. Using a powerful laser as the light source, a custom designed optical assembly, and a high speed digital camera, real time imaging rates up to 30 000 frames per seconds have been demonstrated.

  11. Magneto-optical system for high speed real time imaging.

    PubMed

    Baziljevich, M; Barness, D; Sinvani, M; Perel, E; Shaulov, A; Yeshurun, Y

    2012-08-01

    A new magneto-optical system has been developed to expand the range of high speed real time magneto-optical imaging. A special source for the external magnetic field has also been designed, using a pump solenoid to rapidly excite the field coil. Together with careful modifications of the cryostat, to reduce eddy currents, ramping rates reaching 3000 T/s have been achieved. Using a powerful laser as the light source, a custom designed optical assembly, and a high speed digital camera, real time imaging rates up to 30 000 frames per seconds have been demonstrated. PMID:22938303

  12. The in vivo activation of persistent nanophosphors for optical imaging of vascularization, tumours and grafted cells

    NASA Astrophysics Data System (ADS)

    Maldiney, Thomas; Bessière, Aurélie; Seguin, Johanne; Teston, Eliott; Sharma, Suchinder K.; Viana, Bruno; Bos, Adrie J. J.; Dorenbos, Pieter; Bessodes, Michel; Gourier, Didier; Scherman, Daniel; Richard, Cyrille

    2014-04-01

    Optical imaging for biological applications requires more sensitive tools. Near-infrared persistent luminescence nanoparticles enable highly sensitive in vivo optical detection and complete avoidance of tissue autofluorescence. However, the actual generation of persistent luminescence nanoparticles necessitates ex vivo activation before systemic administration, which prevents long-term imaging in living animals. Here, we introduce a new generation of optical nanoprobes, based on chromium-doped zinc gallate, whose persistent luminescence can be activated in vivo through living tissues using highly penetrating low-energy red photons. Surface functionalization of this photonic probe can be adjusted to favour multiple biomedical applications such as tumour targeting. Notably, we show that cells can endocytose these nanoparticles in vitro and that, after intravenous injection, we can track labelled cells in vivo and follow their biodistribution by a simple whole animal optical detection, opening new perspectives for cell therapy research and for a variety of diagnosis applications.

  13. Peptide-modified optical filters for detecting protease activity.

    PubMed

    Kilian, Kristopher A; Böcking, Till; Gaus, Katharina; Gal, Michael; Gooding, J Justin

    2007-11-01

    The organic derivatization of silicon-based nanoporous photonic crystals is presented as a method to immobilize peptides for the detection of protease enzymes in solution. A narrow-line-width rugate filter, a one-dimensional photonic crystal, is fabricated that exhibits a high-reflectivity optical resonance that is sensitive to small changes in the refractive index at the pore walls. To immobilize peptide in the pore of the photonic crystal, the hydrogen-terminated silicon surface was first modified with the alkene 10-succinimidyl undecenoate via hydrosilylation. The monolayer with the succinimide ester moiety at the distal end served the dual function of protecting the underlying silicon from oxidation as well as providing a surface suitable for subsequent derivatization with amines. The surface was further modified with 1-aminohexa(ethylene glycol) (EG(6)) to resist nonspecific adsorption of proteins common in complex biological samples. The distal hydroxyl of the EG(6) is activated using the solid-phase coupling reagent disuccinimidyl carbonate for selective immobilization of peptides as protease recognition elements. X-ray photoelectron spectroscopy analysis reveals high activation and coupling efficiency at each stage of the functionalization. Exposure of the peptide-modified crystals to the protease subtilisin in solution causes a change in the refractive index, resulting in a shift of the resonance to shorter wavelengths, indicating cleavage of organic material within the pores. The lowest detected concentration of enzyme was 37 nM (7.4 pmol in 200 microL).

  14. Using modalmetric fiber optic sensors to monitor the activity of the heart

    NASA Astrophysics Data System (ADS)

    Życzkowski, M.; Uzięblo-Zyczkowska, B.; Dziuda, L.; Różanowski, K.

    2011-03-01

    The paper presents the concept of the modalmetric fiber optic sensor system for human psychophysical activity detection. A fiber optic sensor that utilizes intensity of propagated light to monitor a patient's vital signs such as respiration cardiac activity, blood pressure and body's physical movements. The sensor, which is non-invasive, comprises an multimode fiber proximately situated to the patient so that time varying acusto-mechanical signals from the patient are coupled by the singlemode optical fiber to detector. The system can be implemented in embodiments ranging form a low cost in-home to a high end product for in hospital use. We present the laboratory test of comparing their results with the known methods like EKG. addition, the article describes the work on integrated system to human psychophysiology activity monitoring. That system including a EMFIT, microwave, fiber optic and capacitive sensors.

  15. Highly nonlinear layered spiral microstructured optical fiber

    NASA Astrophysics Data System (ADS)

    Rodrigues, Sílvia M.; Facão, Margarida M.; Latas, Sofia C.; Ferreira, Mário F.

    2013-08-01

    A layered spiral microstructured optical fiber (LS-MOF) is presented, which offers the possibility of a good control of both the dispersion and the nonlinear properties. The proposed design is analyzed using a finite element method considering silica and air as the materials. Zero dispersion, low confinement loss, and a record value of γ = 70.0 W-1/km for the LS-MOF nonlinear parameter are simultaneously obtained at 1.55 μm, whereas a higher value γ = 169.4 W-1/km can be achieved at 1.06 μm. Our results demonstrate the great potential of the LS-MOF for several nonlinear applications, namely for an efficient generation of the supercontinuum.

  16. High energy, high resolution X-ray optics

    NASA Technical Reports Server (NTRS)

    Weisskopf, Martin C.; Joy, Marshall; Kahn, Steven

    1990-01-01

    The scientific goals of X-ray astronomy are considered to evaluate the relative advantages of using classical Wolter-1 optics or using a different approach. The portion of the X-ray band over 10 keV is unexploited in the present X-ray optics technology, and focussing in this portion of the band is crucial because nonfocussed experiments are background limited. The basic design of 'hard' X-ray optics is described theoretically emphasizing the very small angles of incidence in the grazing-incidence optics. Optimization of the signal-to-noise ratio is found to occur at a finite angular resolution. In real applications, the effective area reduced by the efficiency of the two reflections is 80 percent at energies up to 40 keV, and the quality of the reflecting surface can be monitored to minimize scattering. Focussing optics are found to offer improvements in signal-to-noise as well as more effective scientific return because microelectronic focal-plane technology is employed.

  17. Highly nonlocal optical nonlinearities in atoms trapped near a waveguide

    NASA Astrophysics Data System (ADS)

    Shahmoon, Ephraim; Grisins, Pjotrs; Stimming, Hans Peter; Mazets, Igor; Kurizki, Gershon

    2016-05-01

    Nonlinear optical phenomena are typically local. Here we predict the possibility of highly nonlocal optical nonlinearities for light propagating in atomic media trapped near a nano-waveguide, where long-range interactions between the atoms can be tailored. When the atoms are in an electromagnetically-induced transparency configuration, the atomic interactions are translated to long-range interactions between photons and thus to highly nonlocal optical nonlinearities. We derive and analyze the governing nonlinear propagation equation, finding a roton-like excitation spectrum for light and the emergence of long-range order in its output intensity. These predictions open the door to studies of unexplored wave dynamics and many-body physics with highly-nonlocal interactions of optical fields in one dimension.

  18. Asymmetric bioreduction of activated alkenes to industrially relevant optically active compounds

    PubMed Central

    Winkler, Christoph K.; Tasnádi, Gábor; Clay, Dorina; Hall, Mélanie; Faber, Kurt

    2012-01-01

    Ene-reductases from the ‘Old Yellow Enzyme’ family of flavoproteins catalyze the asymmetric reduction of various α,β-unsaturated compounds at the expense of a nicotinamide cofactor. They have been applied to the synthesis of valuable enantiopure products, including chiral building blocks with broad industrial applications, terpenoids, amino acid derivatives and fragrances. The combination of these highly stereoselective biocatalysts with a cofactor recycling system has allowed the development of cost-effective methods for the generation of optically active molecules, which is strengthened by the availability of stereo-complementary enzyme homologues. PMID:22498437

  19. Asymmetric bioreduction of activated alkenes to industrially relevant optically active compounds.

    PubMed

    Winkler, Christoph K; Tasnádi, Gábor; Clay, Dorina; Hall, Mélanie; Faber, Kurt

    2012-12-31

    Ene-reductases from the 'Old Yellow Enzyme' family of flavoproteins catalyze the asymmetric reduction of various α,β-unsaturated compounds at the expense of a nicotinamide cofactor. They have been applied to the synthesis of valuable enantiopure products, including chiral building blocks with broad industrial applications, terpenoids, amino acid derivatives and fragrances. The combination of these highly stereoselective biocatalysts with a cofactor recycling system has allowed the development of cost-effective methods for the generation of optically active molecules, which is strengthened by the availability of stereo-complementary enzyme homologues.

  20. High quality optically polished aluminum mirror and process for producing

    NASA Technical Reports Server (NTRS)

    Lyons, III, James J. (Inventor); Zaniewski, John J. (Inventor)

    2005-01-01

    A new technical advancement in the field of precision aluminum optics permits high quality optical polishing of aluminum monolith, which, in the field of optics, offers numerous benefits because of its machinability, lightweight, and low cost. This invention combines diamond turning and conventional polishing along with india ink, a newly adopted material, for the polishing to accomplish a significant improvement in surface precision of aluminum monolith for optical purposes. This invention guarantees the precise optical polishing of typical bare aluminum monolith to surface roughness of less than about 30 angstroms rms and preferably about 5 angstroms rms while maintaining a surface figure accuracy in terms of surface figure error of not more than one-fifteenth of wave peak-to-valley.

  1. High quality optically polished aluminum mirror and process for producing

    NASA Technical Reports Server (NTRS)

    Lyons, III, James J. (Inventor); Zaniewski, John J. (Inventor)

    2002-01-01

    A new technical advancement in the field of precision aluminum optics permits high quality optical polishing of aluminum monolith, which, in the field of optics, offers numerous benefits because of its machinability, lightweight, and low cost. This invention combines diamond turning and conventional polishing along with india ink, a newly adopted material, for the polishing to accomplish a significant improvement in surface precision of aluminum monolith for optical purposes. This invention guarantees the precise optical polishing of typical bare aluminum monolith to surface roughness of less than about 30 angstroms rms and preferably about 5 angstroms rms while maintaining a surface figure accuracy in terms of surface figure error of not more than one-fifteenth of wave peak-to-valley.

  2. A digital optical torquemeter for high rotational speed applications

    NASA Technical Reports Server (NTRS)

    Lesco, D. J.; Buchele, D. R.; Oberle, L. G.

    1982-01-01

    A digital optical torquemeter system designed for applications at high rotational speeds was fabricated and tested for zero stability at speeds up to 20,000 rpm. Data obtained in a spin rig and with simulated inputs demonstrate that the system is capable of measuring torque bar twist to within 0.03 degrees at speeds of 30,000 rpm. The optical system uses fiber optic bundles to transmit light to the torque bar and to silicon avalanche detectors. The system is microcomputer based and provides measurements of average torque and torque as a function of angular shaft position. The torquemeter requires no bearings or other contact between the rotating torque bar and the nonrotating optics, and tolerates movement of the torque bar as large as 1 mm relative to the optics.

  3. High Bandwidth Optical Links for Micro-Satellite Support

    NASA Technical Reports Server (NTRS)

    Chao, Tien-Hsin (Inventor); Wilson, Keith E. (Inventor); Coste, Keith (Inventor)

    2016-01-01

    A method, systems, apparatus and device enable high bandwidth satellite communications. An onboard tracking detector, installed in a low-earth orbit satellite, detects a position of an incoming optical beam received/transmitted from a first ground station of one or more ground stations. Tracker electronics determine orientation information of the incoming optical beam based on the position. Control electronics receive the orientation information from the tracker electronics, and control a waveguide drive electronics. The waveguide drive electronics control a voltage that is provided to an electro-optic waveguide beam steering device. The electro-optic waveguide beam steering device steers an outgoing optical beam to one of the one or more ground stations based on the voltage.

  4. Influence of optical activity on rogue waves propagating in chiral optical fibers

    NASA Astrophysics Data System (ADS)

    Temgoua, D. D. Estelle; Kofane, T. C.

    2016-06-01

    We derive the nonlinear Schrödinger (NLS) equation in chiral optical fiber with right- and left-hand nonlinear polarization. We use the similarity transformation to reduce the generalized chiral NLS equation to the higher-order integrable Hirota equation. We present the first- and second-order rational solutions of the chiral NLS equation with variable and constant coefficients, based on the modified Darboux transformation method. For some specific set of parameters, the features of chiral optical rogue waves are analyzed from analytical results, showing the influence of optical activity on waves. We also generate the exact solutions of the two-component coupled nonlinear Schrödinger equations, which describe optical activity effects on the propagation of rogue waves, and their properties in linear and nonlinear coupling cases are investigated. The condition of modulation instability of the background reveals the existence of vector rogue waves and the number of stable and unstable branches. Controllability of chiral optical rogue waves is examined by numerical simulations and may bring potential applications in optical fibers and in many other physical systems.

  5. Influence of optical activity on rogue waves propagating in chiral optical fibers.

    PubMed

    Temgoua, D D Estelle; Kofane, T C

    2016-06-01

    We derive the nonlinear Schrödinger (NLS) equation in chiral optical fiber with right- and left-hand nonlinear polarization. We use the similarity transformation to reduce the generalized chiral NLS equation to the higher-order integrable Hirota equation. We present the first- and second-order rational solutions of the chiral NLS equation with variable and constant coefficients, based on the modified Darboux transformation method. For some specific set of parameters, the features of chiral optical rogue waves are analyzed from analytical results, showing the influence of optical activity on waves. We also generate the exact solutions of the two-component coupled nonlinear Schrödinger equations, which describe optical activity effects on the propagation of rogue waves, and their properties in linear and nonlinear coupling cases are investigated. The condition of modulation instability of the background reveals the existence of vector rogue waves and the number of stable and unstable branches. Controllability of chiral optical rogue waves is examined by numerical simulations and may bring potential applications in optical fibers and in many other physical systems. PMID:27415269

  6. High Performance Lasers and LEDs for Optical Communication

    NASA Astrophysics Data System (ADS)

    Nelson, R. J.

    1987-01-01

    High performance 1.3 um lasers and LEDs have been developed for optical communications systems. The lasers exhibit low threshold currents, excellent high speed and spectral characteristics, and high reliability. The surface emitting LEDs provide launched powers greater than -15 dBm into 62.5 um core fiber with rise and fall times suitable for operation to 220 Mb/s.

  7. Giant optical activity of sugar in thin soap films.

    PubMed

    Emile, Janine; Emile, Olivier; Ghoufi, Aziz; Moréac, Alain; Casanova, Federico; Ding, Minxia; Houizot, Patrick

    2013-10-15

    We report on enhanced experimental optical activity measurements of thin soap films in the presence of sugar. This unusual optical activity is linked to the intramolecular chiral conformation of the glucose molecules at the air/liquid interface. Choosing sodium dodecylsulfate (SDS) as a model surfactant and glucose as model sugar, favorable interactions between the anionic group -OSO3(-)- and the glucose molecules are highlighted. This induces an interfacial anchoring of glucose molecules leading to a perturbing influence of the asymmetric chiral environment. PMID:23932406

  8. Active optics system of the VLT Survey Telescope.

    PubMed

    Schipani, Pietro; Noethe, Lothar; Magrin, Demetrio; Kuijken, Konrad; Arcidiacono, Carmelo; Argomedo, Javier; Capaccioli, Massimo; Dall'Ora, Massimo; D'Orsi, Sergio; Farinato, Jacopo; Fierro, Davide; Holzlöhner, Ronald; Marty, Laurent; Molfese, Cesare; Perrotta, Francesco; Ragazzoni, Roberto; Savarese, Salvatore; Rakich, Andrew; Umbriaco, Gabriele

    2016-03-01

    This paper describes the active optics system of the VLT Survey Telescope, the 2.6-m survey telescope designed for visible wavelengths of the European Southern Observatory at Cerro Paranal, in the Atacama desert. The telescope is characterized by a wide field of view (1.42 deg diameter), leading to tighter active optics than in conventional telescopes, in particular for the alignment requirements. We discuss the effects of typical error sources on the image quality and present the specific solutions adopted for wavefront sensing and correction of the aberrations, which are based on the shaping of a monolithic primary mirror and the positioning of the secondary in five degrees of freedom.

  9. High-throughput proteomics : optical approaches.

    SciTech Connect

    Davidson, George S.

    2008-09-01

    Realistic cell models could greatly accelerate our ability to engineer biochemical pathways and the production of valuable organic products, which would be of great use in the development of biofuels, pharmaceuticals, and the crops for the next green revolution. However, this level of engineering will require a great deal more knowledge about the mechanisms of life than is currently available. In particular, we need to understand the interactome (which proteins interact) as it is situated in the three dimensional geometry of the cell (i.e., a situated interactome), and the regulation/dynamics of these interactions. Methods for optical proteomics have become available that allow the monitoring and even disruption/control of interacting proteins in living cells. Here, a range of these methods is reviewed with respect to their role in elucidating the interactome and the relevant spatial localizations. Development of these technologies and their integration into the core competencies of research organizations can position whole institutions and teams of researchers to lead in both the fundamental science and the engineering applications of cellular biology. That leadership could be particularly important with respect to problems of national urgency centered around security, biofuels, and healthcare.

  10. Optically active biological particle distinguishing apparatus

    DOEpatents

    Salzman, Gary C.; Kupperman, Robert H.

    1989-01-01

    The disclosure is directed to organic particle sorting and identification. High frequency pulses of circularly polarized light, alternating between left and right, intersect a fast moving stream of organic particles. Circular intensity differential scattering and linear intensity differential scattering are monitored to uniquely identify a variety of organic particles.

  11. Optical sensing in high voltage transmission lines using power over fiber and free space optics

    NASA Astrophysics Data System (ADS)

    Rosolem, João Batista; Bassan, Fabio Renato; Penze, Rivael Strobel; Leonardi, Ariovaldo Antonio; Fracarolli, João Paulo Vicentini; Floridia, Claudio

    2015-12-01

    In this work we propose the use of power over fiber (PoF) and free space optics (FSO) techniques to powering and receive signals from an electrical current sensor placed at high voltage potential using a pair of optical collimators. The technique evaluation was performed in a laboratorial prototype using 62.5/125 μm multimode fiber to study the sensitivity of the optical alignment and the influence of the collimation process in the sensing system wavelengths: data communication (1310 nm) and powering (830 nm). The collimators were installed in a rigid electric insulator in order to maintain the stability of transmission.

  12. Cathodoluminescence-activated nanoimaging: noninvasive near-field optical microscopy in an electron microscope.

    PubMed

    Bischak, Connor G; Hetherington, Craig L; Wang, Zhe; Precht, Jake T; Kaz, David M; Schlom, Darrell G; Ginsberg, Naomi S

    2015-05-13

    We demonstrate a new nanoimaging platform in which optical excitations generated by a low-energy electron beam in an ultrathin scintillator are used as a noninvasive, near-field optical scanning probe of an underlying sample. We obtain optical images of Al nanostructures with 46 nm resolution and validate the noninvasiveness of this approach by imaging a conjugated polymer film otherwise incompatible with electron microscopy due to electron-induced damage. The high resolution, speed, and noninvasiveness of this "cathodoluminescence-activated" platform also show promise for super-resolution bioimaging.

  13. Analyses of space environment effects on active fiber optic links orbited aboard the LDEF

    NASA Technical Reports Server (NTRS)

    Taylor, Edward W.; Monarski, T. W.; Berry, J. N.; Sanchez, A. D.; Padden, R. J.; Chapman, S. P.

    1993-01-01

    The results of the 'Preliminary Analysis of WL Experiment no. 701, Space Environment Effects on Operating Fiber Optic Systems,' is correlated with space simulated post retrieval terrestrial studies performed on the M0004 experiment. Temperature cycling measurements were performed on the active optical data links for the purpose of assessing link signal to noise ratio and bit error rate performance some 69 months following the experiment deployment in low Earth orbit. The early results indicate a high correlation between pre-orbit, orbit, and post-orbit functionality of the first known and longest space demonstration of operating fiber optic systems.

  14. Exploring the origin of high optical absorption in conjugated polymers.

    PubMed

    Vezie, Michelle S; Few, Sheridan; Meager, Iain; Pieridou, Galatia; Dörling, Bernhard; Ashraf, Raja Shahid; Goñi, Alejandro R; Bronstein, Hugo; McCulloch, Iain; Hayes, Sophia C; Campoy-Quiles, Mariano; Nelson, Jenny

    2016-07-01

    The specific optical absorption of an organic semiconductor is critical to the performance of organic optoelectronic devices. For example, higher light-harvesting efficiency can lead to higher photocurrent in solar cells that are limited by sub-optimal electrical transport. Here, we compare over 40 conjugated polymers, and find that many different chemical structures share an apparent maximum in their extinction coefficients. However, a diketopyrrolopyrrole-thienothiophene copolymer shows remarkably high optical absorption at relatively low photon energies. By investigating its backbone structure and conformation with measurements and quantum chemical calculations, we find that the high optical absorption can be explained by the high persistence length of the polymer. Accordingly, we demonstrate high absorption in other polymers with high theoretical persistence length. Visible light harvesting may be enhanced in other conjugated polymers through judicious design of the structure. PMID:27183327

  15. Process of making cryogenically cooled high thermal performance crystal optics

    DOEpatents

    Kuzay, T.M.

    1992-06-23

    A method is disclosed for constructing a cooled optic wherein one or more cavities are milled, drilled or formed using casting or ultrasound laser machining techniques in a single crystal base and filled with porous material having high thermal conductivity at cryogenic temperatures. A non-machined strain-free single crystal can be bonded to the base to produce superior optics. During operation of the cooled optic, N[sub 2] is pumped through the porous material at a sub-cooled cryogenic inlet temperature and with sufficient system pressure to prevent the fluid bulk temperature from reaching saturation. 7 figs.

  16. Process of making cryogenically cooled high thermal performance crystal optics

    DOEpatents

    Kuzay, Tuncer M.

    1992-01-01

    A method for constructing a cooled optic wherein one or more cavities are milled, drilled or formed using casting or ultrasound laser machining techniques in a single crystal base and filled with porous material having high thermal conductivity at cryogenic temperatures. A non-machined strain-free single crystal can be bonded to the base to produce superior optics. During operation of the cooled optic, N.sub.2 is pumped through the porous material at a sub-cooled cryogenic inlet temperature and with sufficient system pressure to prevent the fluid bulk temperature from reaching saturation.

  17. Live Cell Optical Sensing for High Throughput Applications

    NASA Astrophysics Data System (ADS)

    Fang, Ye

    Live cell optical sensing employs label-free optical biosensors to non-invasively measure stimulus-induced dynamic mass redistribution (DMR) in live cells within the sensing volume of the biosensor. The resultant DMR signal is an integrated cellular response, and reflects cell signaling mediated through the cellular target(s) with which the stimulus intervenes. This article describes the uses of live cell optical sensing for probing cell biology and ligand pharmacology, with an emphasis of resonant waveguide grating biosensor cellular assays for high throughput applications.

  18. High-speed image matching with coaxial holographic optical correlator

    NASA Astrophysics Data System (ADS)

    Ikeda, Kanami; Watanabe, Eriko

    2016-09-01

    A computation speed of more than 100 Gbps is experimentally demonstrated using our developed ultrahigh-speed optical correlator. To verify this high computation speed practically, the computation speeds of our optical correlator and conventional digital image matching are quantitatively compared. We use a population count function that achieves the fastest calculation speed when calculating binary matching by a central processing unit (CPU). The calculation speed of the optical correlator is dramatically faster than that using a CPU (2.40 GHz × 4) and 16 GB of random access memory, especially when the calculation data are large-scale.

  19. Process of making cryogenically cooled high thermal performance crystal optics

    SciTech Connect

    Kuzay, T.M.

    1990-06-29

    A method for constructing a cooled optic wherein one or more cavities are milled, drilled or formed using casting or ultrasound laser machining techniques in a single crystal base and filled with porous material having high thermal conductivity at cryogenic temperatures. A non-machined strain-free single crystal can be bonded to the base to produce superior optics. During operation of the cooled optic, N{sub 2} is pumped through the porous material at a sub-cooled cryogenic inlet temperature and with sufficient system pressure to prevent the fluid bulk temperature from reaching saturation.

  20. Synthesis of high purity metal oxide nanoparticles for optical applications

    NASA Astrophysics Data System (ADS)

    Baker, C.; Kim, W.; Friebele, E. J.; Villalobos, G.; Frantz, J.; Shaw, L. B.; Sadowski, B.; Fontana, J.; Dubinskii, M.; Zhang, J.; Sanghera, J.

    2014-09-01

    In this paper we present our recent research results in synthesizing various metal oxide nanoparticles for use as laser gain media (solid state as well as fiber lasers) and transparent ceramic windows via two separate techniques, co-precipitation and flame spray pyrolysis. The nanoparticles were pressed into ceramic discs that exhibited optical transmission approaching the theoretical limit and showed very high optical-to-optical lasing slope efficiency. We have also synthesized sesquioxide nanoparticles using a Flame Spray Pyrolysis (FSP) technique that leads to the synthesis of a metastable phase of sesquioxide which allows fabricating excellent optical quality transparent windows with very fine grain sizes. Finally, we present our research in the synthesis of rare earth doped boehmite nanoparticles where the rareearth ion is encased in a cage of aluminum and oxygen to prevent ion-ion proximity and energy transfer. The preforms have been drawn into fibers exhibiting long lifetimes and high laser efficiencies.

  1. Low-loss, high-isolation, fiber-optic isolator

    NASA Technical Reports Server (NTRS)

    Lutes, George F. (Inventor)

    1988-01-01

    A low-loss, high-isolation, fiber-optic isolator for use in single-mode fiber systems utilizes a Faraday rotator and two polarizers, one at each end angularly oriented from each other at the angle of rotation for isolation, and two aspheric lens connectors to couple optical fibers to the Faraday isolator to reduce forward loss to about 2.5 dB and improve isolation to greater than 70 dB.

  2. Design of an Optically Controlled MR-Compatible Active Needle

    PubMed Central

    Ryu, Seok Chang; Quek, Zhan Fan; Koh, Je-Sung; Renaud, Pierre; Black, Richard J.; Moslehi, Behzad; Daniel, Bruce L.; Cho, Kyu-Jin; Cutkosky, Mark R.

    2015-01-01

    An active needle is proposed for the development of magnetic resonance imaging (MRI)-guided percutaneous procedures. The needle uses a low-transition-temperature shape memory alloy (LT SMA) wire actuator to produce bending in the distal section of the needle. Actuation is achieved with internal optical heating using laser light transported via optical fibers and side coupled to the LT SMA. A prototype, with a size equivalent to a standard 16-gauge biopsy needle, exhibits significant bending, with a tip deflection of more than 14° in air and 5° in hard tissue. A single-ended optical sensor with a gold-coated tip is developed to measure the curvature independently of temperature. The experimental results in tissue phantoms show that human tissue causes fast heat dissipation from the wire actuator; however, the active needle can compensate for typical targeting errors during prostate biopsy. PMID:26512231

  3. Laser optical disk position encoder with active heads

    NASA Astrophysics Data System (ADS)

    Osborne, Eric P.

    1992-04-01

    An angular position encoder is provided that minimizes the effects of eccentricity and other misalignments between the disk and the read stations by employing heads which incorporate beam steering optics with the ability to actively track the disk in directions along the disk radius and normal to its surface. The device adapts features prevalent in optical disk technology toward the application of angular position sensing. A reflective disk and the principles of interferometry are employed. The servo-controlled steering optics move so as to acquire a track on the disk lying at a predetermined radius and distance below the head, and then adjust position and orientation in order to maintain the view of the disk track as required. Thus, the device is actively self-aligning.

  4. Laser optical disk position encoder with active heads

    NASA Astrophysics Data System (ADS)

    Osborne, Eric P.

    1990-03-01

    An angular position encoder is provided that minimizes the effects of eccentricity and other misalignments between the disk and the read stations by employing heads which incorporate beam steering optics with the ability to actively track the disk in directions along the disk radius and normal to its surface. The device adapts features prevalent in optical disk technology toward the application of angular position sensing. A reflective disk and the principles of interferometry are employed. The servo-controlled steering optics move so as to acquire a track on the disk lying at a predetermined radius and distance below the head, and then adjust position and orientation in order to maintain the view of the disk track as required. Thus, the device is actively self-aligning.

  5. Quasi-optical solid-state power combining for millimeter-wave active seeker applications

    SciTech Connect

    Halladay, R.H.; Terrill, S.D.; Bowling, D.R.; Gagnon, D.R. U.S. Navy, Naval Air Warfare Center, China Lake, CA )

    1992-05-01

    Consideration is given to quasi-optical power combining techniques, state-of-the-art demonstrated performance, and system issues as they apply to endoatmospheric homing seeker insertion. Quasi-optical power combining is based on combining microwave and millimeter-wave solid-state device power in space through the use of antennas and lenses. It is concluded that quasi-optical power combining meets the severe electrical requirements and packaging constraints of active MMW seekers for endoatmospheric hit-to-kill missiles. The approach provides the possibility of wafer-scale integration of major components for low cost production and offers high reliability. Critical issues include thermal loading and system integration, which must be resolved before the quasi-optical power combining technology will be applied to an active MMW seeker. 18 refs.

  6. Actively mode-locked fiber ring laser by intermodal acousto-optic modulation.

    PubMed

    Bello-Jiménez, M; Cuadrado-Laborde, C; Sáez-Rodríguez, D; Diez, A; Cruz, J L; Andrés, M V

    2010-11-15

    We report an actively mode-locked fiber ring laser. A simple and low-insertion-loss acousto-optic modulator driven by standing flexural waves, which couples core-to-cladding modes in a standard single-mode optical fiber, is used as an active mechanism for mode locking. Among the remarkable features of the modulator, we mention its high modulation depth (72%), broad bandwidth (187 GHz), easy tunability in the optical wavelength, and low insertion losses (0.7 dB). The narrowest optical pulses obtained were of 95 ps time width, 21 mW peak power, repetition rate of 4.758 MHz, and 110 mW of pump power.

  7. Ultra-high accuracy optical testing: creating diffraction-limitedshort-wavelength optical systems

    SciTech Connect

    Goldberg, Kenneth A.; Naulleau, Patrick P.; Rekawa, Senajith B.; Denham, Paul E.; Liddle, J. Alexander; Gullikson, Eric M.; Jackson, KeithH.; Anderson, Erik H.; Taylor, John S.; Sommargren, Gary E.; Chapman,Henry N.; Phillion, Donald W.; Johnson, Michael; Barty, Anton; Soufli,Regina; Spiller, Eberhard A.; Walton, Christopher C.; Bajt, Sasa

    2005-08-03

    Since 1993, research in the fabrication of extreme ultraviolet (EUV) optical imaging systems, conducted at Lawrence Berkeley National Laboratory (LBNL) and Lawrence Livermore National Laboratory (LLNL), has produced the highest resolution optical systems ever made. We have pioneered the development of ultra-high-accuracy optical testing and alignment methods, working at extreme ultraviolet wavelengths, and pushing wavefront-measuring interferometry into the 2-20-nm wavelength range (60-600 eV). These coherent measurement techniques, including lateral shearing interferometry and phase-shifting point-diffraction interferometry (PS/PDI) have achieved RMS wavefront measurement accuracies of 0.5-1-{angstrom} and better for primary aberration terms, enabling the creation of diffraction-limited EUV optics. The measurement accuracy is established using careful null-testing procedures, and has been verified repeatedly through high-resolution imaging. We believe these methods are broadly applicable to the advancement of short-wavelength optical systems including space telescopes, microscope objectives, projection lenses, synchrotron beamline optics, diffractive and holographic optics, and more. Measurements have been performed on a tunable undulator beamline at LBNL's Advanced Light Source (ALS), optimized for high coherent flux; although many of these techniques should be adaptable to alternative ultraviolet, EUV, and soft x-ray light sources. To date, we have measured nine prototype all-reflective EUV optical systems with NA values between 0.08 and 0.30 (f/6.25 to f/1.67). These projection-imaging lenses were created for the semiconductor industry's advanced research in EUV photolithography, a technology slated for introduction in 2009-13. This paper reviews the methods used and our program's accomplishments to date.

  8. Special issue on high-resolution optical imaging

    NASA Astrophysics Data System (ADS)

    Smith, Peter J. S.; Davis, Ilan; Galbraith, Catherine G.; Stemmer, Andreas

    2013-09-01

    The pace of development in the field of advanced microscopy is truly breath-taking, and is leading to major breakthroughs in our understanding of molecular machines and cell function. This special issue of Journal of Optics draws attention to a number of interesting approaches, ranging from fluorescence and imaging of unlabelled cells, to computational methods, all of which are describing the ever increasing detail of the dynamic behaviour of molecules in the living cell. This is a field which traditionally, and currently, demonstrates a marvellous interplay between the disciplines of physics, chemistry and biology, where apparent boundaries to resolution dissolve and living cells are viewed in ever more clarity. It is fertile ground for those interested in optics and non-conventional imaging to contribute high-impact outputs in the fields of cell biology and biomedicine. The series of articles presented here has been selected to demonstrate this interdisciplinarity and to encourage all those with a background in the physical sciences to 'dip their toes' into the exciting and dynamic discoveries surrounding cell function. Although single molecule super-resolution microscopy is commercially available, specimen preparation and interpretation of single molecule data remain a major challenge for scientists wanting to adopt the techniques. The paper by Allen and Davidson [1] provides a much needed detailed introduction to the practical aspects of stochastic optical reconstruction microscopy, including sample preparation, image acquisition and image analysis, as well as a brief description of the different variants of single molecule localization microscopy. Since super-resolution microscopy is no longer restricted to three-dimensional imaging of fixed samples, the review by Fiolka [2] is a timely introduction to techniques that have been successfully applied to four-dimensional live cell super-resolution microscopy. The combination of multiple high-resolution techniques

  9. Backward reflection analysis of transmitting channel of active laser ranging optics

    NASA Astrophysics Data System (ADS)

    Hong, Jinsuk; Koh, Hae Seog

    2013-09-01

    The designed Active LDR(Laser Detection and Ranging) System contains high-power Laser and its diameter is approximately 24mm. Although the laser transmitting channel and receiving optic channel are completely separated from each other and doesn't share any of the optical components in design, each channel shares 4 wedge scanners, which are to overcome the narrow FOV(Field of View) of the optical system. Any backward reflection back to the fiber laser end must be carefully studied since it can damage the LD(Laser Diodes), the inner components of the laser unit because of the high amplification factor of the laser unit. In this study, the stray light caused by the transmitting channel's laser and inner reflection by optical components were analyzed by ASAP(Advanced System Analysis Program) software. We also can confirm the operability and stability of the system by more than 6 months of operation of the system.

  10. Optical imaging of neural and hemodynamic brain activity

    NASA Astrophysics Data System (ADS)

    Schei, Jennifer Lynn

    Optical imaging technologies can be used to record neural and hemodynamic activity. Neural activity elicits physiological changes that alter the optical tissue properties. Specifically, changes in polarized light are concomitant with neural depolarization. We measured polarization changes from an isolated lobster nerve during action potential propagation using both reflected and transmitted light. In transmission mode, polarization changes were largest throughout the center of the nerve, suggesting that most of the optical signal arose from the inner nerve bundle. In reflection mode, polarization changes were largest near the edges, suggesting that most of the optical signal arose from the outer sheath. To overcome irregular cell orientation found in the brain, we measured polarization changes from a nerve tied in a knot. Our results show that neural activation produces polarization changes that can be imaged even without regular cell orientations. Neural activation expends energy resources and elicits metabolic delivery through blood vessel dilation, increasing blood flow and volume. We used spectroscopic imaging techniques combined with electrophysiological measurements to record evoked neural and hemodynamic responses from the auditory cortex of the rat. By using implantable optics, we measured responses across natural wake and sleep states, as well as responses following different amounts of sleep deprivation. During quiet sleep, evoked metabolic responses were larger compared to wake, perhaps because blood vessels were more compliant. When animals were sleep deprived, evoked hemodynamic responses were smaller following longer periods of deprivation. These results suggest that prolonged neural activity through sleep deprivation may diminish vascular compliance as indicated by the blunted vascular response. Subsequent sleep may allow vessels to relax, restoring their ability to deliver blood. These results also suggest that severe sleep deprivation or chronic

  11. High-performance parallel interface to synchronous optical network gateway

    DOEpatents

    St. John, Wallace B.; DuBois, David H.

    1996-01-01

    A system of sending and receiving gateways interconnects high speed data interfaces, e.g., HIPPI interfaces, through fiber optic links, e.g., a SONET network. An electronic stripe distributor distributes bytes of data from a first interface at the sending gateway onto parallel fiber optics of the fiber optic link to form transmitted data. An electronic stripe collector receives the transmitted data on the parallel fiber optics and reforms the data into a format effective for input to a second interface at the receiving gateway. Preferably, an error correcting syndrome is constructed at the sending gateway and sent with a data frame so that transmission errors can be detected and corrected in a real-time basis. Since the high speed data interface operates faster than any of the fiber optic links the transmission rate must be adapted to match the available number of fiber optic links so the sending and receiving gateways monitor the availability of fiber links and adjust the data throughput accordingly. In another aspect, the receiving gateway must have sufficient available buffer capacity to accept an incoming data frame. A credit-based flow control system provides for continuously updating the sending gateway on the available buffer capacity at the receiving gateway.

  12. High-performance parallel interface to synchronous optical network gateway

    DOEpatents

    St. John, W.B.; DuBois, D.H.

    1996-12-03

    Disclosed is a system of sending and receiving gateways interconnects high speed data interfaces, e.g., HIPPI interfaces, through fiber optic links, e.g., a SONET network. An electronic stripe distributor distributes bytes of data from a first interface at the sending gateway onto parallel fiber optics of the fiber optic link to form transmitted data. An electronic stripe collector receives the transmitted data on the parallel fiber optics and reforms the data into a format effective for input to a second interface at the receiving gateway. Preferably, an error correcting syndrome is constructed at the sending gateway and sent with a data frame so that transmission errors can be detected and corrected in a real-time basis. Since the high speed data interface operates faster than any of the fiber optic links the transmission rate must be adapted to match the available number of fiber optic links so the sending and receiving gateways monitor the availability of fiber links and adjust the data throughput accordingly. In another aspect, the receiving gateway must have sufficient available buffer capacity to accept an incoming data frame. A credit-based flow control system provides for continuously updating the sending gateway on the available buffer capacity at the receiving gateway. 7 figs.

  13. A highly versatile optical fibre vacuum feed-through

    NASA Astrophysics Data System (ADS)

    Davidson, Ian A.; Azzouz, Hatim; Hueck, Klaus; Bourennane, Mohamed

    2016-05-01

    Coupling light into a vacuum system is a non-trivial problem, requiring the use of a specialized feed-through. This feed-through must be both leak tight and offer a low optical loss if it is to be suitable for general use. In this paper, we report on the development of an extremely simple yet versatile, low cost, demountable optical fiber vacuum feed-through based on the modification of a standard optical fiber bulkhead connector. The modified connector was found to have a leak rate of 6.6 ± 2.1 × 10-6 mbar l/s and an optical loss of -0.41 ± 0.28 dB, making it suitable for use in high vacuum applications.

  14. Study of passive and active optical waveguides: Synthesis, processing and characterization of materials

    NASA Astrophysics Data System (ADS)

    Yoshida, Makoto

    Photonics uses photons for information and image processing, and has been touted as the technology of the 21 st century. An optical waveguide is a key component of an optical integrated circuit which is the optical analog of an electrical integrated circuit (IC). Electrical transistor IC technology resulted in an enormous impact on society, and it changed our life styles from the age of the vacuum tube. The advent of the optical integrated circuit is expected to have the same impact on society as the electronic IC. Various optical circuit elements are interrelated to materials, therefore, the study and the better understanding of materials and processing have been receiving a great deal of attention. My research focuses on the study of optical waveguide materials and their processings in terms of passive and active optical waveguides. The first target was to establish a method for measuring the refractive index and optical propagation loss of optical waveguides. The second target was to develop passive waveguide materials which can route, split and combine optical signals on a substrate. There are several requirements for waveguiding, such as high optical transparency, proper refractive index, and proper thickness. The sol-gel technique was used to meet the requirements, and several types of organic: inorganic composite materials were developed. The third target involved the development of processing methods to fabricate channel waveguides using the above-mentioned passive and active waveguide materials. Selective laser densification was developed for sol-gel composite materials. Use of trenched substrates and photobleaching were also studied. The last target was to develop an active material which could process optical signals using the electrooptic effect. A crosslinked urethane polymer with a newly synthesized chromophore was used due to its high thermal stability and optical transparency. In order to obtain second order nonlinearity, macroscopic molecular

  15. High-Throughput Optical Sensing Immunoassays on Smartphone.

    PubMed

    Wang, Li-Ju; Sun, Rongrong; Vasile, Tina; Chang, Yu-Chung; Li, Lei

    2016-08-16

    We present an optical sensing platform on a smartphone for high-throughput screening immunoassays. For the first time, a designed microprism array is utilized to achieve a one-time screening of 64 samples. To demonstrate the capability and the reliability of this optical sensing platform on smartphone, human interleukin 6 (IL-6) protein and six types of plant viruses are immunoassayed. The ability of quantification is shown by a sigmoidal dose-response curve fitting to analyze IL-6 protein. The accuracy in measuring the concentrations of IL-6 protein achieves 99.1%. On the other hand, to validate on-field immunoassays by our device, a total of 1030 samples are assayed using three immunoassay methods to detect six types of plant viruses. The accuracy is up to 96.2-99.9%; in addition, there is a high degree of agreement with lab instruments. The total cost for this high-throughput optical screening platform is ∼$50 USD. The reading time is only 2 s for 64 samples. The size is just as big as a portable hard drive. Our optical sensing platform on the smartphone offers a route toward in situ high-throughput screening immunoassays for viruses, pathogens, biomarkers, and toxins by decentralizing laboratory tests. With this mobile point-of-care optical platform, the spread of disease can be timely stopped within a very short turnaround time. PMID:27434250

  16. Impact of optical antennas on active optoelectronic devices.

    PubMed

    Bonakdar, Alireza; Mohseni, Hooman

    2014-10-01

    Remarkable progress has been made in the fabrication and characterization of optical antennas that are integrated with optoelectronic devices. Herein, we describe the fundamental reasons for and experimental evidence of the dramatic improvements that can be achieved by enhancing the light-matter interaction via an optical antenna in both photon-emitting and -detecting devices. In addition, integration of optical antennas with optoelectronic devices can lead to the realization of highly compact multifunctional platforms for future integrated photonics, such as low-cost lab-on-chip systems. In this review paper, we further focus on the effect of optical antennas on the detectivity of infrared photodetectors. One particular finding is that the antenna can have a dual effect on the specific detectivity, while it can elevate light absorption efficiency of sub-wavelength detectors, it can potentially increase the noise of the detectors due to the enhanced spontaneous emission rate. In particular, we predict that the detectivity of interband photon detectors can be negatively affected by the presence of optical antennas across a wide wavelength region covering visible to long wavelength infrared bands. In contrast, the detectivity of intersubband detectors could be generally improved with a properly designed optical antenna.

  17. High-density Au nanorod optical field-emitter arrays

    NASA Astrophysics Data System (ADS)

    Hobbs, R. G.; Yang, Y.; Keathley, P. D.; Swanwick, M. E.; Velásquez-García, L. F.; Kärtner, F. X.; Graves, W. S.; Berggren, K. K.

    2014-11-01

    We demonstrate the design, fabrication, characterization, and operation of high-density arrays of Au nanorod electron emitters, fabricated by high-resolution electron beam lithography, and excited by ultrafast femtosecond near-infrared radiation. Electron emission characteristic of multiphoton absorption has been observed at low laser fluence, as indicated by the power-law scaling of emission current with applied optical power. The onset of space-charge-limited current and strong optical field emission has been investigated so as to determine the mechanism of electron emission at high incident laser fluence. Laser-induced structural damage has been observed at applied optical fields above 5 GV m-1, and energy spectra of emitted electrons have been measured using an electron time-of-flight spectrometer.

  18. Kepler Observations of Rapid Optical Variability in Active Galactic Nuclei

    NASA Technical Reports Server (NTRS)

    Mushotzky, R. F.; Edelson, R.; Baumgartner, W. H.; Gandhi, P.

    2012-01-01

    Over three quarters in 2010 - 2011, Kepler monitored optical emission from four active galactic nuclei (AGN) with approx 30 min sampling, > 90% duty cycle and approx < 0.1% repeatability. These data determined the AGN optical fluctuation power spectral density functions (PSDs) over a wide range in temporal frequency. Fits to these PSDs yielded power law slopes of -2.6 to -3.3, much steeper than typically seen in the X-rays. We find evidence that individual AGN exhibit intrinsically different PSD slopes. The steep PSD fits are a challenge to recent AGN variability models but seem consistent with first order MRI theoretical calculations of accretion disk fluctuations.

  19. Pattern matching based active optical sorting of colloids/cells

    NASA Astrophysics Data System (ADS)

    Verma, R. S.; Dasgupta, R.; Ahlawat, S.; Kumar, N.; Uppal, A.; Gupta, P. K.

    2013-08-01

    We report active optical sorting of colloids/cells by employing a cross correlation based pattern matching technique for selection of the desired objects and thereafter sorting using dynamically controllable holographic optical traps. The problem of possible collision between the different sets of objects during sorting was avoided by raising one set of particles to a different plane. We also present the results obtained on using this approach for some representative applications such as sorting of silica particles of two different sizes, of closely packed colloids and of white blood cells and red blood cells from a mixture of the two.

  20. Novel silica surface charge density mediated control of the optical properties of embedded optically active materials and its application for fiber optic pH sensing at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Wang, Congjun; Ohodnicki, Paul R.; Su, Xin; Keller, Murphy; Brown, Thomas D.; Baltrus, John P.

    2015-01-01

    Silica and silica incorporated nanocomposite materials have been extensively studied for a wide range of applications. Here we demonstrate an intriguing optical effect of silica that, depending on the solution pH, amplifies or attenuates the optical absorption of a variety of embedded optically active materials with very distinct properties, such as plasmonic Au nanoparticles, non-plasmonic Pt nanoparticles, and the organic dye rhodamine B (not a pH indicator), coated on an optical fiber. Interestingly, the observed optical response to varying pH appears to follow the surface charge density of the silica matrix for all the three different optically active materials. To the best of our knowledge, this optical effect has not been previously reported and it appears universal in that it is likely that any optically active material can be incorporated into the silica matrix to respond to solution pH or surface charge density variations. A direct application of this effect is for optical pH sensing which has very attractive features that can enable minimally invasive, remote, real time and continuous distributed pH monitoring. Particularly, as demonstrated here, using highly stable metal nanoparticles embedded in an inorganic silica matrix can significantly improve the capability of pH sensing in extremely harsh environments which is of increasing importance for applications in unconventional oil and gas resource recovery, carbon sequestration, water quality monitoring, etc. Our approach opens a pathway towards possible future development of robust optical pH sensors for the most demanding environmental conditions. The newly discovered optical effect of silica also offers the potential for control of the optical properties of optically active materials for a range of other potential applications such as electrochromic devices.Silica and silica incorporated nanocomposite materials have been extensively studied for a wide range of applications. Here we demonstrate an

  1. Optical activity in planar chiral metamaterials: Theoretical study

    SciTech Connect

    Bai, Benfeng; Svirko, Yuri; Turunen, Jari; Vallius, Tuomas

    2007-08-15

    A thorough theoretical study of the optical activity in planar chiral metamaterial (PCM) structures, made of both dielectric and metallic media, is conducted by the analysis of gammadion-shaped nanoparticle arrays. The general polarization properties are first analyzed from an effective-medium perspective, by analogy with natural optical activity, and then verified by rigorous numerical simulation, some of which are corroborated by previous experimental results. The numerical analysis suggests that giant polarization rotation (tens of degrees) may be achieved in the PCM structures with a thickness of only hundreds of nanometers. The artificial optical activity arises from circular birefringence induced by the structural chirality and is enhanced by the guided-mode or surface-plasmon resonances taking place in the structures. There are two polarization conversion types in the dielectric PCMs, whereas only one type in the metallic ones. Many intriguing features of the polarization property of PCMs are also revealed and explained: the polarization effect is reciprocal and vanishes in the symmetrically layered structures; the effect occurs only in the transmitted field, but not in the reflected field; and the polarization spectra of two enantiomeric PCM structures are mirror symmetric to each other. These remarkable properties pave the way for the PCMs to be used as polarization elements in new-generation integrated optical systems.

  2. High-energy devices, optics and photography

    NASA Astrophysics Data System (ADS)

    Borodio, K.

    1986-01-01

    Using a unit for catching high energy particles form space in an experiment called Pamir, scientists have obtained new data on interactions between these particles and nuclei of atoms of matter. According to a hypothesis of physicists, electromagnetic fields operating in space and in supernova stars which flare up from time to time accelerate particles to energies which are hundreds of thousands or even millions of times as high as those which can be obtained on Earth. Something resembling a layer cake with layers of lead and a special x ray film in lightproof and waterproof packages was set up on a level area at an elevation of almost 5,000 meters in the Pamir Mountains. This cake covers an area of almost 1,000 square meters. A single x ray film takes up about a hectare. Particles enter the x ray emulsion chamber and form spots on the film. The particles' energy nd the character of their interaction with nuclei of atoms of matter can be judged on the basis of these spots.

  3. New high performance Si for optical devices

    NASA Astrophysics Data System (ADS)

    Tenma, T.; Matsuzaka, M.; Sako, R.; Takase, K.; Chiba, K.

    2016-05-01

    Against the backdrop of a growing demand in the areas of smart buildings, security, vehicle installation, and other applications, the market for far infrared cameras is expected to grow significantly in the future. However, since germanium (Ge) and chalcogenide glass, which have been used as the lens materials of far infrared cameras, are very expensive or highly toxic, there are some problems supporting the growing demand. We have therefore focused attention on silicon, which is inexpensive and less toxic. Although silicon has been used as a lens material of far infrared cameras, there are some problems remaining to be solved: Cz silicon is inexpensive but delivers low transmittance, and Fz silicon delivers sufficient transmittance but is expensive. We have developed New Cz silicon, which delivers high transmittance as Fz silicon does, and is inexpensive as conventional Cz silicon is. We have already started its sample work at both companies in Japan and overseas and have obtained excellent performance results. Mass production is scheduled to start in this fiscal year.

  4. High-Sensitivity Optical Pulse Characterization Using Sagnac Electro-Optic Spectral Shearing Interferometry

    SciTech Connect

    Dorrer, C.; Bromage, J.

    2010-05-04

    An electro-optic spectral shearing interferometer for high-sensitivity optical pulse characterization is described. Two replicas of the test pulse counterpropagate in a Sagnac interferometer with orthogonal polarization states, resulting in two relatively sheared copolarized replicas after temporal phase modulation. The polarization interferometer is intrinsically stable, and its birefringence sets the delay between interfering replicas to reduce the spectrometer resolution requirement. Experimental implementations demonstrate real-time pulse characterization at average powers as low as 1 nWwith spectral shears as high as 280 GHz.

  5. Optically induced mode splitting in self-assembled, high quality-factor conjugated polymer microcavities

    PubMed Central

    Braam, Daniel; Kushida, Soh; Niemöller, Robert; Prinz, Günther M.; Saito, Hitoshi; Kanbara, Takaki; Kuwabara, Junpei; Yamamoto, Yohei; Lorke, Axel

    2016-01-01

    We investigate the whispering gallery modes (WGMs) of self-assembled single microspheres. They consist of a recently developed highly fluorescent π-conjugated copolymer and exhibit excellent optical properties with Q-factors up to 104. Under continuous laser irradiation, we observe a splitting of the highly degenerate spherical WGMs into a multiplet of lines. Comparison with the calculated spectral response of a weakly distorted sphere shows that the optical excitation induces a change of the optical path length in the microcavity so that it resembles a prolate spheroid. The separation of the lines is given by the ellipticity and the azimuthal mode number. Measurements in various gaseous environments suggest that the distortion is caused by light induced oxidation of the polymer. Our findings show that photooxidation can be a beneficial mechanism for in-situ tuning of optically active polymer structures. PMID:26781838

  6. High NA Nicrostepper Final Optical Design Report

    SciTech Connect

    Hudyma, R

    1999-09-24

    The development of a new EUV high NA small-field exposure tool has been proposed for obtaining mask defect printability data in a timeframe several years before beta-tools are available. The imaging system for this new Micro-Exposure Tool (MET), would have a numerical aperture (NA) of about 0.3, similar to the NA for a beta-tool, but substantially larger than the 0.10 NA for the Engineering Test Stand (ETS) and 0.088 NA for the existing 10x Microstepper. This memorandum discusses the development and summarizes the performance of the camera for the MET and includes a listing of the design prescription, detailed analysis of the distortion, and analysis demonstrating the capability to resolution 30 nm features under the conditions of partially coherent illumination.

  7. Optical packaging activities at Institute of Microelectronics (IME), Singapore

    NASA Astrophysics Data System (ADS)

    Teo, Keng-Hwa; Sudharsanam, Krishnamachari; Pamidighantam, Ramana V.; Yeo, Yongkee; Iyer, Mahadevan K.

    2002-08-01

    The development of optoelectronic components for gigabit Ethernet communications is converging towards access networks where the cost of device makes a significant impact on the market acceptance. Device fabrication and packaging cost have to be brought down with novel assembly and packaging methods. Singapore has established a reputation in semiconductor device development and fabrication with excellent process and packaging facilities. Institute of Microelectronics (IME) was founded in 1991 to add value to the Singapore electronics industry. IME is involved in the development of active and passive photonics components using Silicon and polymer materials. We present a brief report on the development activities taking place in the field of optical component packaging at IME in recent years. We present a review of our competence and some of the optical device packaging activities that are being undertaken.

  8. Development of a fiber optic high temperature strain sensor

    NASA Technical Reports Server (NTRS)

    Rausch, E. O.; Murphy, K. E.; Brookshire, S. P.

    1992-01-01

    From 1 Apr. 1991 to 31 Aug. 1992, the Georgia Tech Research Institute conducted a research program to develop a high temperature fiber optic strain sensor as part of a measurement program for the space shuttle booster rocket motor. The major objectives of this program were divided into four tasks. Under Task 1, the literature on high-temperature fiber optic strain sensors was reviewed. Task 2 addressed the design and fabrication of the strain sensor. Tests and calibration were conducted under Task 3, and Task 4 was to generate recommendations for a follow-on study of a distributed strain sensor. Task 4 was submitted to NASA as a separate proposal.

  9. Optical ordnance system for use in explosive ordnance disposal activities

    NASA Technical Reports Server (NTRS)

    Merson, J. A.; Salas, F. J.; Helsel, F.M.

    1994-01-01

    A portable hand-held solid state rod laser system and an optically-ignited detonator have been developed for use in explosive ordnance disposal (EOD) activities. Laser prototypes from Whittaker Ordnance and Universal Propulsion have been tested and evaluated. The optical detonator contains 2-(5 cyanotetrazolato) pentaamine cobalt(III) perchlorate (CP) as the DDT column and the explosive Octahydro- 1,3,5,7 - tetrazocine (HMX) as the output charge. The laser is designed to have an output of 150 mJ in a 500 microsecond pulse. This output allows firing through 2000 meters of optical fiber. The detonator can also be ignited with a portable laser diode source through a shorter length of fiber.

  10. Optical ordance system for use in explosive ordnance disposal activities

    SciTech Connect

    Merson, J.A.; Salas, F.J.; Helsel, F.M.

    1994-01-01

    A portable hand-held solid state rod laser system and an optically-ignited detonator have been developed for use in explosive ordnance disposal (EOD) activities. Laser prototypes from Whittaker Ordnance and Universal Propulsion have been tested and evaluated. The optical detonator contains 2-(5 cyanotetrazolato) pentaamine cobalt III perchlorate (CP) as the DDT column and the explosive Octahydro 1, 3, 5, 7 -- tetranitro -- 1, 3, 5, 7 -- tetrazocine (HMX) as the output charge. The laser is designed to have an output of 150 mJ in a 500 microsecond pulse. This output allows firing through 2000 meters of optical fiber. The detonator can also be ignited with a portable laser diode source through a shorter length of fiber.

  11. High precision metrology of domes and aspheric optics

    NASA Astrophysics Data System (ADS)

    Murphy, Paul E.; Fleig, Jon; Forbes, Greg; Tricard, Marc

    2005-05-01

    Many defense systems have a critical need for high-precision, complex optics. However, fabrication of high quality, advanced optics is often seriously hampered by the lack of accurate and affordable metrology. QED's Subaperture Stitching Interferometer (SSI®) provides a breakthrough technology, enabling the automatic capture of precise metrology data for large and/or strongly curved (concave and convex) parts. QED"s SSI complements next-generation finishing technologies, such as Magnetorheological Finishing (MRF®), by extending the effective aperture, accuracy and dynamic range of a phase-shifting interferometer. This workstation performs automated sub-aperture stitching measurements of spheres, flats, and mild aspheres. It combines a six-axis precision stage system, a commercial Fizeau interferometer, and specially developed software that automates measurement design, data acquisition, and the reconstruction of the full-aperture figure error map. Aside from the correction of sub-aperture placement errors (such as tilts, optical power, and registration effects), our software also accounts for reference-wave error, distortion and other aberrations in the interferometer"s imaging optics. The SSI can automatically measure the full aperture of high numerical aperture surfaces (such as domes) to interferometric accuracy. The SSI extends the usability of a phase measuring interferometer and allows users with minimal training to produce full-aperture measurements of otherwise untestable parts. Work continues to extend this technology to measure aspheric shapes without the use of dedicated null optics. This SSI technology will be described, sample measurement results shown, and various manufacturing applications discussed.

  12. Conformal optical elements for correcting wavefront distortions in YAG : Nd{sup 3+} active elements

    SciTech Connect

    Korolkov, V P; Nasyrov, R K; Poleshchuk, A G; Arapov, Yu D; Ivanov, A F

    2013-02-28

    Correction of the wavefront is studied for the light beam passing wide-aperture YAG : Nd3+ single-crystal rods, which are used as active elements in high-power solid-state lasers. A nonideal character of the crystal structure is responsible for the deformation of the wavefront of passing radiation. By using the halftone technology we have developed conformal aberration correctors capable of compensating rod nonuniformities and reducing the laser radiation divergence by an order of magnitude. The results obtained make it possible to employ optically nonuniform active elements in laser constructions. (laser optics 2012)

  13. Continued education and experimental activities for optics education

    NASA Astrophysics Data System (ADS)

    Shinomiya, George K.; Muramatsu, Mikiya

    2001-08-01

    Of the evidence that the optics knowledge is practically unknown for the pupils who complete Basic Education, we initiate, in 1998, a project involving teachers of the Public Network and University teachers with the objective to change this situation. The main cause of this abandonment of optics is the bad understanding by the teachers of the optic phenomena, result of their bad initial formation. Based on this situation, we developed a series of simple experimental activities that demonstrate the main concepts of optics in the program. After that, we elaborate courses of university extension, destined to the teachers of Basic Education, giving emphasis to the experimentation, using kits and demonstrations, complemented by texts, videos and group works. From 98 until now, more than 200 teachers had participated of our course, and they made a sufficiently positive evaluation of these works pointing not only the including of the optics, but also a significant change in its strategies of education, going of meeting to the new parameters of our basic education.

  14. Optical macro-tweezers: trapping of highly motile micro-organisms

    NASA Astrophysics Data System (ADS)

    Thalhammer, G.; Steiger, R.; Bernet, S.; Ritsch-Marte, M.

    2011-04-01

    Optical micromanipulation stands for contact-free handling of microscopic particles by light. Optical forces can manipulate non-absorbing objects in a large range of sizes, e.g., from biological cells down to cold atoms. Recently much progress has been made going from the micro- down to the nanoscale. Less attention has been paid to going the other way, trapping increasingly large particles. Optical tweezers typically employ a single laser beam tightly focused by a microscope objective of high numerical aperture to stably trap a particle in three dimensions (3D). As the particle size increases, stable 3D trapping in a single-beam trap requires scaling up the optical power, which eventually induces adverse biological effects. Moreover, the restricted field of view of standard optical tweezers, dictated by the use of high NA objectives, is particularly unfavorable for catching actively moving specimens. Both problems can be overcome by traps with counter-propagating beams. Our 'macro-tweezers' are especially designed to trap highly motile organisms, as they enable three-dimensional all-optical trapping and guiding in a volume of 2 × 1 × 2 mm3. Here we report for the first time the optical trapping of large actively swimming organisms, such as for instance Euglena protists and dinoflagellates of up to 70 µm length. Adverse bio-effects are kept low since trapping occurs outside high intensity regions, e.g., focal spots. We expect our approach to open various possibilities in the contact-free handling of 50-100 µm sized objects that could hitherto not be envisaged, for instance all-optical holding of individual micro-organisms for taxonomic identification, selective collecting or tagging.

  15. Reliability of high power laser diodes with external optical feedback

    NASA Astrophysics Data System (ADS)

    Bonsendorf, Dennis; Schneider, Stephan; Meinschien, Jens; Tomm, Jens W.

    2016-03-01

    Direct diode laser systems gain importance in the fields of material processing and solid-state laser pumping. With increased output power, also the influence of strong optical feedback has to be considered. Uncontrolled optical feedback is known for its spectral and power fluctuation effects, as well as potential emitter damage. We found that even intended feedback by use of volume Bragg gratings (VBG) for spectral stabilization may result in emitter lifetime reduction. To provide stable and reliable laser systems design, guidelines and maximum feedback ratings have to be found. We present a model to estimate the optical feedback power coupled back into the laser diode waveguide. It includes several origins of optical feedback and wide range of optical elements. The failure thresholds of InGaAs and AlGaAs bars have been determined not only at standard operation mode but at various working points. The influence of several feedback levels to laser diode lifetime is investigated up to 4000h. The analysis of the semiconductor itself leads to a better understanding of the degradation process by defect spread. Facet microscopy, LBIC- and electroluminescence measurements deliver detailed information about semiconductor defects before and after aging tests. Laser diode protection systems can monitor optical feedback. With this improved understanding, the emergency shutdown threshold can be set low enough to ensure laser diode reliability but also high enough to provide better machine usability avoiding false alarms.

  16. Fiber Lasers and all Optical Logic Gates for Header Processing in High-Bit Optical Networks

    NASA Astrophysics Data System (ADS)

    Barnett, Brandon Craig

    As information technologies push network capacities toward higher bit rates, fiber-optic communication networks will eventually be capable of transmitting data at a rate at which electronic switches cannot respond. A solution to this problem is to replace the electronics at the front and back ends of the transmission system where data enters and exists in optical format with all-optical header processors. In this thesis, I will describe how the header processor has been divided into all-optical switching modules, which will act as the basic building block for the header processing unit. Each module arises from the integration of an erbium -doped fiber laser and an all-optical logic gate. The erbium-doped fiber laser (EDFL) acts as a local power supply for the module. It restores the pulse shape, pulse amplitude, and timing of an incoming optical bit stream. The development of a short-pulse EDFL and a high-power EDFL for this application is described. The high-power EDFL employs a unique cavity design that eliminates multiple pulses when pumped with high powers. Data processing is performed within the module by all-optical logic gates, which switch due to the nonlinear interaction of one pulse of light with another in optical fiber. Therefore, these gates can work at the bit rate of the transmission system and avoid the bottlenecks inherent in electronic processors. The design and demonstration of a low-latency soliton-dragging gate and a low-birefringent nonlinear optical loop mirror (low-bi NOLM) logic gate are described. The two logic gates are optimized for energy contrast, switching energy, timing sensitivity, and cascadability. Logic functionality is also demonstrated. The thesis culminates in an experiment that integrates the laser and logic gate work by driving two cascaded low -bi NOLM's with an EDFL. It is shown that this experiment utilizes all the components necessary to read the header of a high-bit-rate data packet, bringing closure to the switching

  17. Metal-Coated Optical Fibers for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Zeakes, Jason; Murphy, Kent; Claus, Richard; Greene, Jonathan; Tran, Tuan

    1996-01-01

    A DC magnetron sputtering system has been used to actively coat optical fibers with hermetic metal coatings during the fiber draw process. Thin films of Inconel 625 have been deposited on optical fibers and annealed in air at 2000 F. Scanning electron microscopy and Auger electron microscopy have been used to investigate the morphology and composition of the films prior to and following thermal cycling. Issues to be addressed include film adhesion, other coating materials, and a discussion of additional applications for this novel technology.

  18. Optical transcutaneous link for low power, high data rate telemetry.

    PubMed

    Liu, Tianyi; Bihr, Ulrich; Anis, Syed M; Ortmanns, Maurits

    2012-01-01

    A low power and high data rate wireless optical link for implantable data transmission is presented in this paper. In some neural prosthetic applications particularly in regard to neural recording system, there is a demand for high speed communication between an implanted device and an external device. An optical transcutaneous link is a promising implantable telemetry solution, since it shows lower power requirements than RF telemetry. In this paper, this advantage is further enhanced by using a modified on-off keying and a simple custom designed low power VCSEL driver. This transmitter achieves an optical transcutaneous link capable of transmitting data at 50 Mbps through the 4 mm tissue, with a tolerance of 2 mm misalignment and a BER of less than 10(-5), while the power consumption is only 4.1 mW or less. PMID:23366690

  19. Fiber optic, Fabry-Perot high temperature sensor

    NASA Technical Reports Server (NTRS)

    James, K.; Quick, B.

    1984-01-01

    A digital, fiber optic temperature sensor using a variable Fabry-Perot cavity as the sensor element was analyzed, designed, fabricated, and tested. The fiber transmitted cavity reflection spectra is dispersed then converted from an optical signal to electrical information by a charged coupled device (CCD). A microprocessor-based color demodulation system converts the wavelength information to temperature. This general sensor concept not only utilizes an all-optical means of parameter sensing and transmitting, but also exploits microprocessor technology for automated control, calibration, and enhanced performance. The complete temperature sensor system was evaluated in the laboratory. Results show that the Fabry-Perot temperature sensor has good resolution (0.5% of full seale), high accuracy, and potential high temperature ( 1000 C) applications.

  20. Optical lightpipe as a high-bandwidth fusion diagnostic

    NASA Astrophysics Data System (ADS)

    Moran, M. J.; Lerche, R. A.; Mant, G.; Glebov, V. Yu.; Sangster, T. C.; Mack, J. M.

    2006-10-01

    A recent series of experiments at the University of Rochester Laboratory for Laser Energetics OMEGA facility studied the feasibility of using radiation-to-light converters and high-bandwidth optical signal transmission to remote recording devices as an alternate nuclear diagnostic method. A prototype system included a radiation-to-light converter, a multiple-section lightpipe consisting of stainless steel tubes with polished interiors and turning mirrors, and a streak camera or photomultiplier/digitizer combination for signal recording. Several different radiation-to-light converters (scintillators, glasses, plastics, and pressurized CO2) performed well and produced predictable optical emissions. The lightpipe transmitted high-bandwidth optical signals to the recording stations. Data were recorded with the streak camera, the photomultiplier/digitizer, and with both recorders simultaneously.

  1. Workshop on high heat load x-ray optics

    SciTech Connect

    Not Available

    1990-01-01

    A workshop on High Heat Load X-Ray Optics'' was held at Argonne National Laboratory on August 3--5, 1989. The object of this workshop was to discuss recent advances in the art of cooling x-ray optics subject to high heat loads from synchrotron beams. The cooling of the first optical element in the intense photon beams that will be produced in the next generation of synchrotron sources is recognized as one of the major challenges that must be faced before one will be able to use these very intense beams in future synchrotron experiments. Considerable advances have been made in this art during the last few years, but much work remains to be done before the heating problem can be said to be completely solved. Special emphasis was placed on recent cooling experiments and detailed finite element'' and finite difference'' calculations comparing experiment with theory and extending theory to optimize performance.

  2. The Optical Lightpipe as a High-Bandwidth Fusion Diagnostic

    SciTech Connect

    Moran, M J; Lerche, R A; Mant, G; Glebov, V Y; Sangster, T C; Mack, J M

    2006-07-21

    A recent series of experiments at the University of Rochester Laboratory for Laser Energetics OMEGA facility studied the feasibility of using radiation-to-light converters and high bandwidth optical signal transmission to remote recording devices as an alternate nuclear diagnostic method. A prototype system included a radiation-to-light converter, a multiple-section light pipe consisting of stainless steel tubes with polished interiors and turning mirrors, and a streak camera or photomultiplier/digitizer combination for signal recording. Several different radiation-to-light converters (scintillators, glasses, plastics, and pressurized CO{sub 2}) performed well and produced predictable optical emissions. The lightpipe transmitted high-bandwidth optical signals to the recording stations. Data were recorded with the streak camera, the photomultiplier/digitizer, and with both recorders simultaneously.

  3. Localization of cortical tissue optical changes during seizure activity in vivo with optical coherence tomography

    PubMed Central

    Eberle, Melissa M.; Hsu, Mike S.; Rodriguez, Carissa L.; Szu, Jenny I.; Oliveira, Michael C.; Binder, Devin K.; Park, B. Hyle

    2015-01-01

    Optical coherence tomography (OCT) is a high resolution, minimally invasive imaging technique, which can produce depth-resolved cross-sectional images. In this study, OCT was used to detect changes in the optical properties of cortical tissue in vivo in mice during the induction of global (pentylenetetrazol) and focal (4-aminopyridine) seizures. Through the use of a confidence interval statistical method on depth-resolved volumes of attenuation coefficient, we demonstrated localization of regions exhibiting both significant positive and negative changes in attenuation coefficient, as well as differentiating between global and focal seizure propagation. PMID:26137382

  4. Optical sensor based system to monitor caries activity

    NASA Astrophysics Data System (ADS)

    Shrestha, A.; Tahir, R.; Kishen, A.

    2007-07-01

    The aim of the study is to evaluate the ability of a visible light based spectroscopic sensor system to monitor caries activity in saliva. In this study an optical sensor is utilized to monitor the bacterial-mediated acidogenic profile of stimulated saliva using a photosensitive pH indicator. Microbiological assessment of the saliva samples were carried out using the conventional culture methods. In addition, the shifts in the pH of saliva-sucrose samples were recorded using a pH meter. The absorption spectra obtained from the optical sensor showed peak maxima at 595nm, which decreased as a function of time. The microbiological assessment showed increase in the bacterial count as a function of time. A strong positive correlation was also observed between the rates of decrease in the absorption intensity measured using the optical sensor and the decrease in pH measured using the pH meter. This study highlights the potential advantages of using the optical sensor as a sensitive and rapid chairside system for monitoring caries activity by quantification of the acidogenic profile of saliva.

  5. Novel silica surface charge density mediated control of the optical properties of embedded optically active materials and its application for fiber optic pH sensing at elevated temperatures.

    PubMed

    Wang, Congjun; Ohodnicki, Paul R; Su, Xin; Keller, Murphy; Brown, Thomas D; Baltrus, John P

    2015-02-14

    Silica and silica incorporated nanocomposite materials have been extensively studied for a wide range of applications. Here we demonstrate an intriguing optical effect of silica that, depending on the solution pH, amplifies or attenuates the optical absorption of a variety of embedded optically active materials with very distinct properties, such as plasmonic Au nanoparticles, non-plasmonic Pt nanoparticles, and the organic dye rhodamine B (not a pH indicator), coated on an optical fiber. Interestingly, the observed optical response to varying pH appears to follow the surface charge density of the silica matrix for all the three different optically active materials. To the best of our knowledge, this optical effect has not been previously reported and it appears universal in that it is likely that any optically active material can be incorporated into the silica matrix to respond to solution pH or surface charge density variations. A direct application of this effect is for optical pH sensing which has very attractive features that can enable minimally invasive, remote, real time and continuous distributed pH monitoring. Particularly, as demonstrated here, using highly stable metal nanoparticles embedded in an inorganic silica matrix can significantly improve the capability of pH sensing in extremely harsh environments which is of increasing importance for applications in unconventional oil and gas resource recovery, carbon sequestration, water quality monitoring, etc. Our approach opens a pathway towards possible future development of robust optical pH sensors for the most demanding environmental conditions. The newly discovered optical effect of silica also offers the potential for control of the optical properties of optically active materials for a range of other potential applications such as electrochromic devices. PMID:25572664

  6. Novel silica surface charge density mediated control of the optical properties of embedded optically active materials and its application for fiber optic pH sensing at elevated temperatures.

    PubMed

    Wang, Congjun; Ohodnicki, Paul R; Su, Xin; Keller, Murphy; Brown, Thomas D; Baltrus, John P

    2015-02-14

    Silica and silica incorporated nanocomposite materials have been extensively studied for a wide range of applications. Here we demonstrate an intriguing optical effect of silica that, depending on the solution pH, amplifies or attenuates the optical absorption of a variety of embedded optically active materials with very distinct properties, such as plasmonic Au nanoparticles, non-plasmonic Pt nanoparticles, and the organic dye rhodamine B (not a pH indicator), coated on an optical fiber. Interestingly, the observed optical response to varying pH appears to follow the surface charge density of the silica matrix for all the three different optically active materials. To the best of our knowledge, this optical effect has not been previously reported and it appears universal in that it is likely that any optically active material can be incorporated into the silica matrix to respond to solution pH or surface charge density variations. A direct application of this effect is for optical pH sensing which has very attractive features that can enable minimally invasive, remote, real time and continuous distributed pH monitoring. Particularly, as demonstrated here, using highly stable metal nanoparticles embedded in an inorganic silica matrix can significantly improve the capability of pH sensing in extremely harsh environments which is of increasing importance for applications in unconventional oil and gas resource recovery, carbon sequestration, water quality monitoring, etc. Our approach opens a pathway towards possible future development of robust optical pH sensors for the most demanding environmental conditions. The newly discovered optical effect of silica also offers the potential for control of the optical properties of optically active materials for a range of other potential applications such as electrochromic devices.

  7. All-Optical Ultrasound Transducers for High Resolution Imaging

    NASA Astrophysics Data System (ADS)

    Sheaff, Clay Smith

    High frequency ultrasound (HFUS) has increasingly been used within the past few decades to provide high resolution (< 200 mum) imaging in medical applications such as endoluminal imaging, intravascular imaging, ophthalmology, and dermatology. The optical detection and generation of HFUS using thin films offers numerous advantages over traditional piezoelectric technology. Circumvention of an electronic interface with the device head is one of the most significant given the RF noise, crosstalk, and reduced capacitance that encumbers small-scale electronic transducers. Thin film Fabry-Perot interferometers - also known as etalons - are well suited for HFUS receivers on account of their high sensitivity, wide bandwidth, and ease of fabrication. In addition, thin films can be used to generate HFUS when irradiated with optical pulses - a method referred to as Thermoelastic Ultrasound Generation (TUG). By integrating a polyimide (PI) film for TUG into an etalon receiver, we have created for the first time an all-optical ultrasound transducer that is both thermally stable and capable of forming fully sampled 2-D imaging arrays of arbitrary configuration. Here we report (1) the design and fabrication of PI-etalon transducers; (2) an evaluation of their optical and acoustic performance parameters; (3) the ability to conduct high-resolution imaging with synthetic 2-D arrays of PI-etalon elements; and (4) work towards a fiber optic PI-etalon for in vivo use. Successful development of a fiber optic imager would provide a unique field-of-view thereby exposing an abundance of prospects for minimally-invasive analysis, diagnosis, and treatment of disease.

  8. Precision optical slit for high heat load or ultra high vacuum

    DOEpatents

    Andresen, Nord C.; DiGennaro, Richard S.; Swain, Thomas L.

    1995-01-01

    This invention relates generally to slits used in optics that must be precisely aligned and adjusted. The optical slits of the present invention are useful in x-ray optics, x-ray beam lines, optical systems in which the entrance slit is critical for high wavelength resolution. The invention is particularly useful in ultra high vacuum systems where lubricants are difficult to use and designs which avoid the movement of metal parts against one another are important, such as monochrometers for high wavelength resolution with ultra high vacuum systems. The invention further relates to optical systems in which temperature characteristics of the slit materials is important. The present invention yet additionally relates to precision slits wherein the opposing edges of the slit must be precisely moved relative to a center line between the edges with each edge retaining its parallel orientation with respect to the other edge and/or the center line.

  9. Precision optical slit for high heat load or ultra high vacuum

    DOEpatents

    Andresen, N.C.; DiGennaro, R.S.; Swain, T.L.

    1995-01-24

    This invention relates generally to slits used in optics that must be precisely aligned and adjusted. The optical slits of the present invention are useful in x-ray optics, x-ray beam lines, optical systems in which the entrance slit is critical for high wavelength resolution. The invention is particularly useful in ultra high vacuum systems where lubricants are difficult to use and designs which avoid the movement of metal parts against one another are important, such as monochromators for high wavelength resolution with ultra high vacuum systems. The invention further relates to optical systems in which temperature characteristics of the slit materials is important. The present invention yet additionally relates to precision slits wherein the opposing edges of the slit must be precisely moved relative to a center line between the edges with each edge retaining its parallel orientation with respect to the other edge and/or the center line. 21 figures.

  10. Transparent selective illumination means suitable for use in optically activated electrical switches and optically activated electrical switches constructed using same

    DOEpatents

    Wilcox, R.B.

    1991-09-10

    A planar transparent light conducting means and an improved optically activated electrical switch made using the novel light conducting means are disclosed. The light conducting means further comprise light scattering means on one or more opposite planar surfaces thereof to transmit light from the light conducting means into adjacent media and reflective means on other surfaces of the light conducting means not containing the light scattering means. The optically activated electrical switch comprises at least two stacked photoconductive wafers, each having electrodes formed on both surfaces thereof, and separated by the planar transparent light conducting means. The light scattering means on the light conducting means face surfaces of the wafers not covered by the electrodes to transmit light from the light conducting means into the photoconductive wafers to uniformly illuminate and activate the switch. 11 figures.

  11. Transparent selective illumination means suitable for use in optically activated electrical switches and optically activated electrical switches constructed using same

    DOEpatents

    Wilcox, Russell B.

    1991-01-01

    A planar transparent light conducting means and an improved optically activated electrical switch made using the novel light conducting means are disclosed. The light conducting means further comprise light scattering means on one or more opposite planar surfaces thereof to transmit light from the light conducting means into adjacent media and reflective means on other surfaces of the light conducting means not containing the light scattering means. The optically activated electrical switch comprises at least two stacked photoconductive wafers, each having electrodes formed on both surfaces thereof, and separated by the planar transparent light conducting means. The light scattering means on the light conducting means face surfaces of the wafers not covered by the electrodes to transmit light from the light conducting means into the photoconductive wafers to uniformly illuminate and activate the switch.

  12. ASIC-enabled High Resolution Optical Time Domain Reflectometer

    NASA Astrophysics Data System (ADS)

    Skendzic, Sandra

    Fiber optics has become the preferred technology in communication systems because of what it has to offer: high data transmission rates, immunity to electromagnetic interference, and lightweight, flexible cables. An optical time domain reflectometer (OTDR) provides a convenient method of locating and diagnosing faults (e.g. break in a fiber) along a fiber that can obstruct crucial optical pathways. Both the ability to resolve the precise location of the fault and distinguish between two discrete, closely spaced faults are figures of merit. This thesis presents an implementation of a high resolution OTDR through the use of a compact and programmable ASIC (application specific integrated circuit). The integration of many essential OTDR functions on a single chip is advantageous over existing commercial instruments because it enables small, lightweight packaging, and offers low power and cost efficiency. Furthermore, its compactness presents the option of placing multiple ASICs in parallel, which can conceivably ease the characterization of densely populated fiber optic networks. The OTDR ASIC consists of a tunable clock, pattern generator, precise timer, electrical receiver, and signal sampling circuit. During OTDR operation, the chip generates narrow electrical pulse, which can then be converted to optical format when coupled with an external laser diode driver. The ASIC also works with an external photodetector to measure the timing and amplitude of optical reflections in a fiber. It has a 1 cm sampling resolution, which allows for a 2 cm spatial resolution. While this OTDR ASIC has been previously demonstrated for multimode fiber fault diagnostics, this thesis focuses on extending its functionality to single mode fiber. To validate this novel approach to OTDR, this thesis is divided into five chapters: (1) introduction, (2) implementation, (3), performance of ASIC-based OTDR, (4) exploration in optical pre-amplification with a semiconductor optical amplifier, and

  13. Optical Illusions: A Presentation for High School Mathematics Students.

    ERIC Educational Resources Information Center

    Brandes, Louis Grant

    1983-01-01

    Optical illusions are assumed to be of interest to high school mathematics students. The article indicates how a topic can be both educational and entertaining. Readers are invited to try to construct some illusions on their own, and to see if they can classify them. (MP)

  14. Integrated optical gyroscope using active long-range surface plasmon-polariton waveguide resonator.

    PubMed

    Zhang, Tong; Qian, Guang; Wang, Yang-Yang; Xue, Xiao-Jun; Shan, Feng; Li, Ruo-Zhou; Wu, Jing-Yuan; Zhang, Xiao-Yang

    2014-01-24

    Optical gyroscopes with high sensitivity are important rotation sensors for inertial navigation systems. Here, we present the concept of integrated resonant optical gyroscope constructed by active long-range surface plasmon-polariton (LRSPP) waveguide resonator. In this gyroscope, LRSPP waveguide doped gain medium is pumped to compensate the propagation loss, which has lower pump noise than that of conventional optical waveguide. Peculiar properties of single-polarization of LRSPP waveguide have been found to significantly reduce the polarization error. The metal layer of LRSPP waveguide is electro-optical multiplexed for suppression of reciprocal noises. It shows a limited sensitivity of ~10(-4) deg/h, and a maximum zero drift which is 4 orders of magnitude lower than that constructed by conventional single-mode waveguide.

  15. Active optics system of the VLT Survey Telescope.

    PubMed

    Schipani, Pietro; Noethe, Lothar; Magrin, Demetrio; Kuijken, Konrad; Arcidiacono, Carmelo; Argomedo, Javier; Capaccioli, Massimo; Dall'Ora, Massimo; D'Orsi, Sergio; Farinato, Jacopo; Fierro, Davide; Holzlöhner, Ronald; Marty, Laurent; Molfese, Cesare; Perrotta, Francesco; Ragazzoni, Roberto; Savarese, Salvatore; Rakich, Andrew; Umbriaco, Gabriele

    2016-03-01

    This paper describes the active optics system of the VLT Survey Telescope, the 2.6-m survey telescope designed for visible wavelengths of the European Southern Observatory at Cerro Paranal, in the Atacama desert. The telescope is characterized by a wide field of view (1.42 deg diameter), leading to tighter active optics than in conventional telescopes, in particular for the alignment requirements. We discuss the effects of typical error sources on the image quality and present the specific solutions adopted for wavefront sensing and correction of the aberrations, which are based on the shaping of a monolithic primary mirror and the positioning of the secondary in five degrees of freedom. PMID:26974616

  16. Dispersion of optical activity of magnesium sulfite hexahydrate single crystals

    NASA Astrophysics Data System (ADS)

    Dimov, T.; Bunzarov, Zh; Iliev, I.; Petkova, P.; Tzoukrovski, Y.

    2010-11-01

    The magnesium sulfite hexahydrate (MgSO3.6H2O) crystals are unique because they are the only representative (with sodium periodate) of the crystallographic class C3 (without a center of symmetry). The crystal symmetry suggests presence of nonlinearity, piezo- and pyro-electric properties and gyrotropy as well. Single crystals of MgSO3.6H2O (pure and doped with Ni, Co and Zn) for the time being are grown only by the original method developed in the Laboratory for Crystal growth at the Faculty of Physics in Sofia University. The first results of optical activity of pure MgSO3.6H2O and Zn doped MgSO3.6H2O crystals are described and analyzed in a wide spectral range. The optical activity manifests itself in the direction (0001) as a rotation of the polarization plane.

  17. Laser-heating-based active optics for synchrotron radiation applications.

    PubMed

    Yang, Fugui; Li, Ming; Gao, Lidan; Sheng, Weifan; Liu, Peng; Zhang, Xiaowei

    2016-06-15

    Active optics has attracted considerable interest from researchers in synchrotron radiation facilities because of its capacity for x-ray wavefront correction. Here, we report a novel and efficient technique for correcting or modulating a mirror surface profile based on laser-heating-induced thermal expansion. An experimental study of the characteristics of the surface thermal deformation response indicates that the power of a milliwatt laser yields a bump height as low as the subnanometer scale and that the variation of the spot size modulates the response function width effectively. In addition, the capacity of the laser-heating technique for free-form surface modulation is demonstrated via a one-dimensional surface correction experiment. The developed method is a promising new approach toward effective x-ray active optics coupled with at-wavelength metrology techniques.

  18. Optical activity of transparent polymer layers characterized by spectral means

    NASA Astrophysics Data System (ADS)

    Cosutchi, Andreea Irina; Dimitriu, Dan Gheorghe; Zelinschi, Carmen Beatrice; Breaban, Iuliana; Dorohoi, Dana Ortansa

    2015-06-01

    The method based on the channeled spectrum, validated for inorganic optical active layers, is used now to determine the optical activity of some transparent polymer solutions in different solvents. The circular birefringence, the dispersion parameter and the specific rotation were estimated in the visible range by using the measurements of wavelengths in the channeled spectra of Hydroxypropyl cellulose in water, methanol and acetic acid. The experiments showed the specific rotation dependence on the polymer concentration and also on the solvent nature. The decrease of the specific rotation in the visible range with the increase in wavelength was evidenced. The method has some advantages as the rapidity of the experiments and the large spectral range in which it can be applied. One disadvantage is the fact that the channeled spectrum does not allow to establish the rotation sense of the electric field intensity.

  19. Laser-heating-based active optics for synchrotron radiation applications.

    PubMed

    Yang, Fugui; Li, Ming; Gao, Lidan; Sheng, Weifan; Liu, Peng; Zhang, Xiaowei

    2016-06-15

    Active optics has attracted considerable interest from researchers in synchrotron radiation facilities because of its capacity for x-ray wavefront correction. Here, we report a novel and efficient technique for correcting or modulating a mirror surface profile based on laser-heating-induced thermal expansion. An experimental study of the characteristics of the surface thermal deformation response indicates that the power of a milliwatt laser yields a bump height as low as the subnanometer scale and that the variation of the spot size modulates the response function width effectively. In addition, the capacity of the laser-heating technique for free-form surface modulation is demonstrated via a one-dimensional surface correction experiment. The developed method is a promising new approach toward effective x-ray active optics coupled with at-wavelength metrology techniques. PMID:27304296

  20. Active optical system design for the 4.2-m SOAR telescope

    NASA Astrophysics Data System (ADS)

    Krabbendam, Victor L.; Ruthven, Gregory P.; Bennett, Victor P.; Blackburn, John P.; Cox, Charles D.; Keung, Chi S.; Facey, Terence A.; Furber, Mark E.; Neufeld, Conrad; Rockwell, Richard A.; Sarnik, Andrea M.; Stein, John T.

    2000-07-01

    The SOAR Telescope project has embarked on the development of a very high quality 4.2-meter diameter optical telescope to be sited on Cerro Pachon in Chile. The telescope will feature an image quality of 0.18 arc seconds, a moderate field of 11 arc minutes, a very large instrument payload capacity for as many as 9 hot instruments, and an Active Optical System optimized for the optical to near IR wavelengths. The active optical system features a 10 cm thick ULETM primary mirror supported by 120 electro- mechanical actuators for a highly correctable surface. the 0.6 meter diameter secondary is articulated by a hexapod for real time optical alignment. The 0.6-meter class tertiary will provide fast beam steering to compensate for atmospheric turbulence at 50 hertz and a turret for directing the light to either of two nasmyth or three-bent cassegrain ports. Both the secondary and tertiary are light- weighted by machining to achieve cost-effective low weight mirrors. This paper discusses the unique features of this development effort including many commercial products and software programs that enable its technical feasibility and high cost efficiency.

  1. Synthesis of Optically Active Polystyrene Catalyzed by Monophosphine Pd Complexes.

    PubMed

    Jouffroy, Matthieu; Armspach, Dominique; Matt, Dominique; Osakada, Kohtaro; Takeuchi, Daisuke

    2016-07-11

    Cationic Pd(II) monophosphine complexes derived from α- and β-cyclodextrins (CDs) promote the homopolymerization of styrene under carbon monoxide pressure. Although reversible CO coordination takes place under catalytic conditions according to (13) C NMR studies with (13) C-enriched CO, both complexes catalyze the formation of CO-free styrene polymers. These macromolecules display optical activity as a result of the presence of stereoregular sequences within the overall atactic polymer.

  2. Final Report: Imaging of Buried Nanoscale Optically Active Materials

    SciTech Connect

    Appelbaum, Ian

    2011-07-05

    This is a final report covering work done at University of Maryland to develop a Ballistic Electron Emission Luminescence (BEEL) microscope. This technique was intended to examine the carrier transport and photon emission in deeply buried optically-active layers and thereby provide a means for materials science to unmask the detailed consequences of experimentally controllable growth parameters, such as quantum dot size, statistics and orientation, and defect density and charge recombination pathways.

  3. Demonstrating Optical Activity Using an iPad

    ERIC Educational Resources Information Center

    Schwartz, Pauline M.; Lepore, Dante M.; Morneau, Brandy N.; Barratt, Carl

    2011-01-01

    Optical activity using an iPad as a source of polarized light is demonstrated. A sample crystal or solution can be placed on the iPad running a white screen app. The sample is viewed through a polarized filter that can be rotated. This setup can be used in the laboratory or with a document camera to easily project in a large lecture hall.…

  4. Synthesis of Optically Active Polystyrene Catalyzed by Monophosphine Pd Complexes.

    PubMed

    Jouffroy, Matthieu; Armspach, Dominique; Matt, Dominique; Osakada, Kohtaro; Takeuchi, Daisuke

    2016-07-11

    Cationic Pd(II) monophosphine complexes derived from α- and β-cyclodextrins (CDs) promote the homopolymerization of styrene under carbon monoxide pressure. Although reversible CO coordination takes place under catalytic conditions according to (13) C NMR studies with (13) C-enriched CO, both complexes catalyze the formation of CO-free styrene polymers. These macromolecules display optical activity as a result of the presence of stereoregular sequences within the overall atactic polymer. PMID:27218801

  5. Active optics control of VST telescope secondary mirror.

    PubMed

    Schipani, Pietro; D'Orsi, Sergio; Fierro, Davide; Marty, Laurent

    2010-06-01

    In telescopes based on active optics, defocus and coma are usually compensated for by secondary mirror movements. They are performed at the Very Large Telescope Survey Telescope (VST) with a hexapod--a parallel robot with six degrees of freedom positioning capability. We describe the application of the two-mirror telescope theory to the VST case and the solutions adopted for the hexapod control. We present the results of performance and reliability tests performed both in the laboratory and at the telescope.

  6. Development of fluorides for high power laser optics

    SciTech Connect

    Ready, J.F.; Vora, H.

    1980-07-01

    The laser-assisted thermonuclear fusion program has significant needs for improved optical materials with high transmission in the ultraviolet, and with low values of nonlinear index of refraction. Lithium fluoride (LiF) possesses a combination of optical properties which are of potential use. Single-crystalline LiF is limited by low mechanical strength. In this program, we investigated the technique of press-forging to increase the mechanical strength. LiF single crystals were press-forged over the temperature range 300 to 600/sup 0/C to produce fine-grained polycrystalline material.

  7. On a possibility high resolution optical tomograph design

    NASA Astrophysics Data System (ADS)

    Khohlov, K. L.; Sokolov, V. K.

    2006-04-01

    An actual problem of the modern medicine is statement of the diagnosis of diseases of a thyroid gland of the person. Extreme sensitivity of this organ to a X-ray radiation and invasive to methods puts a problem about development of an optical tomograph of a high solution. For this purpose the method of coherent optical detection (CDT) in a combination to a posteriori handling can be used with the purpose of elimination of influence of a spread function of a figuring system.

  8. High-Resolution Mammography Detector Employing Optical Switching Readout

    NASA Astrophysics Data System (ADS)

    Irisawa, Kaku; Kaneko, Yasuhisa; Yamane, Katsutoshi; Sendai, Tomonari; Hosoi, Yuichi

    Conceiving a new detector structure, FUJIFILM Corporation has successfully put its invention of an X-ray detector employing "Optical Switching" into practical use. Since Optical Switching Technology allows an electrode structure to be easily designed, both high resolution of pixel pitch and low electrical noise readout have been achieved, which have consequently realized the world's smallest pixel size of 50×50 μm2 from a Direct-conversion FPD system as well as high DQE. The digital mammography system equipped with this detector enables to acquire high definition images while maintaining granularity. Its outstanding feature is to be able to acquire high-precision images of microcalcifications which is an important index in breast examination.

  9. Optical measurement techniques for high Reynolds number train investigations

    NASA Astrophysics Data System (ADS)

    Loose, S.; Richard, H.; Bosbach, J.; Thimm, M.; Becker, W.; Raffel, M.

    2006-04-01

    This article reports on experimental aerodynamic investigations on a generic high-speed train configuration performed within two different wind tunnels. Both wind tunnels are specialized facilities for high Reynolds number investigations and offer low turbulence levels. The wind tunnels are the cryogenic wind tunnel located in Cologne (KKK) and in the high-pressure wind tunnel located in Göttingen (HDG). Both facilities are part of the German Dutch wind tunnel association (DNW). The adaptation and application of three optical measurement techniques for such high Reynolds number investigations is described in the article. The optical methods are: Particle Image Velocimetry for the measurement of velocity fields, Background Oriented Schlieren technique for density gradient measurements, and a white light Digital Speckle Photography technique for model deformation monitoring.

  10. High speed demodulation systems for fiber optic grating sensors

    NASA Technical Reports Server (NTRS)

    Udd, Eric (Inventor); Weisshaar, Andreas (Inventor)

    2002-01-01

    Fiber optic grating sensor demodulation systems are described that offer high speed and multiplexing options for both single and multiple parameter fiber optic grating sensors. To attain very high speeds for single parameter fiber grating sensors ratio techniques are used that allow a series of sensors to be placed in a single fiber while retaining high speed capability. These methods can be extended to multiparameter fiber grating sensors. Optimization of speeds can be obtained by minimizing the number of spectral peaks that must be processed and it is shown that two or three spectral peak measurements may in specific multiparameter applications offer comparable or better performance than processing four spectral peaks. Combining the ratio methods with minimization of peak measurements allows very high speed measurement of such important environmental effects as transverse strain and pressure.

  11. Activities report of the Division of Optical Technology (FOA 33)

    NASA Astrophysics Data System (ADS)

    Letalick, Dietmar

    1988-11-01

    Research on hydro-optics; laser remote sensing; coherent CO2 laser radar; optical signatures; atmospheric transmission; ionizing radiation effects on electronics; fiber optics; optical processing; and terrain models is summarized.

  12. High throughput optoelectronic smart pixel systems using diffractive optics

    NASA Astrophysics Data System (ADS)

    Chen, Chih-Hao

    1999-12-01

    Recent developments in digital video, multimedia technology and data networks have greatly increased the demand for high bandwidth communication channels and high throughput data processing. Electronics is particularly suited for switching, amplification and logic functions, while optics is more suitable for interconnections and communications with lower energy and crosstalk. In this research, we present the design, testing, integration and demonstration of several optoelectronic smart pixel devices and system architectures. These systems integrate electronic switching/processing capability with parallel optical interconnections to provide high throughput network communication and pipeline data processing. The Smart Pixel Array Cellular Logic processor (SPARCL) is designed in 0.8 m m CMOS and hybrid integrated with Multiple-Quantum-Well (MQW) devices for pipeline image processing. The Smart Pixel Network Interface (SAPIENT) is designed in 0.6 m m GaAs and monolithically integrated with LEDs to implement a highly parallel optical interconnection network. The Translucent Smart Pixel Array (TRANSPAR) design is implemented in two different versions. The first version, TRANSPAR-MQW, is designed in 0.5 m m CMOS and flip-chip integrated with MQW devices to provide 2-D pipeline processing and translucent networking using the Carrier- Sense-MultipleAccess/Collision-Detection (CSMA/CD) protocol. The other version, TRANSPAR-VM, is designed in 1.2 m m CMOS and discretely integrated with VCSEL-MSM (Vertical-Cavity-Surface- Emitting-Laser and Metal-Semiconductor-Metal detectors) chips and driver/receiver chips on a printed circuit board. The TRANSPAR-VM provides an option of using the token ring network protocol in addition to the embedded functions of TRANSPAR-MQW. These optoelectronic smart pixel systems also require micro-optics devices to provide high resolution, high quality optical interconnections and external source arrays. In this research, we describe an innovative

  13. Study of Optical Mode Scrambling of Fiber Optics for High Precision Radial Velocity Measurements

    NASA Astrophysics Data System (ADS)

    Cassette, Anthony; Ge, Jian; Jeram, Sarik; Klanot, Khaya; Ma, Bo; Varosi, Frank

    2016-01-01

    Optical Fibers have been used throughout Astronomy for spectroscopy with spectrographs located some distance away from the telescope. This fiber-fed design has greatly increased precision for radial velocity (RV) measurements. However, due to the incomplete fiber illumination mode scrambling in the radial direction, high resolution spectrographs with regular circular fibers have suffered RV uncertainties on the order of a few to tens of m/s with stellar observations, which largely limited their sensitivity in detecting and characterizing low mass planets around stars. At the University of Florida, we studied mode scrambling gain of a few different optical devices, such as three-lens optical double scramblers, octagonal fibers and low numerical aperture fibers with a goal to find an optimal mode scrambling solution for the TOU optical very high resolution spectrograph (R=100,000, 0.38-0.9 microns) and FIRST near infrared high resolution spectrograph (R=60,000, 0.9-1.8 microns) for the on-going Dharma Planet Survey. This presentation will report our lab measurement results and also stellar RV measurements at the observatories.

  14. New High Speed File Format for High Definition Television Optical Disks

    NASA Astrophysics Data System (ADS)

    Ishikawa, Kiyohiko; Koide, Daiichi; Kishida, Masahiko; Tokumaru, Haruki; Nakamura, Shoich

    2004-07-01

    Optical disk systems have advantages over video cassette recorders for broadcasting because they provide excellent random access, reliability and archiving performance. However, the transfer data rates of optical disks are inadequate for use in broadcasting applications. An optical disk medium, a servo system and signal processing techniques were developed for a 200 Mbps read/write system with two optical heads that was aimed at application to high definition television (HDTV) news gathering. We also developed an original disk format (ODF) that features a new high speed file format which has two new characteristics for HDTV. One is a guaranteed minimum extent length and the other is separation of the recording areas for files and directories. Our high-speed optical disk emulator proved that ODF is requiered to achieve a consecutive data transfer rate of more than 200 Mbps per head.

  15. Optical control system for high-voltage terminals

    DOEpatents

    Bicek, John J.

    1978-01-01

    An optical control system for the control of devices in the terminal of an electrostatic accelerator includes a laser that is modulated by a series of preselected codes produced by an encoder. A photodiode receiver is placed in the laser beam at the high-voltage terminal of an electrostatic accelerator. A decoder connected to the photodiode decodes the signals to provide control impulses for a plurality of devices at the high voltage of the terminal.

  16. Bendable X-ray Optics for High Resolution Imaging

    NASA Technical Reports Server (NTRS)

    Gubarev, M.; Ramsey, B.; Kilaru, K.; Atkins, C.; Broadway, D.

    2014-01-01

    Current state-of the-art for x-ray optics fabrication calls for either the polishing of massive substrates into high-angular-resolution mirrors or the replication of thin, lower-resolution, mirrors from perfectly figured mandrels. Future X-ray Missions will require a change in this optics fabrication paradigm in order to achieve sub-arcsecond resolution in light-weight optics. One possible approach to this is to start with perfectly flat, light-weight surface, bend it into a perfect cone, form the desired mirror figure by material deposition, and insert the resulting mirror into a telescope structure. Such an approach is currently being investigated at MSFC, and a status report will be presented detailing the results of finite element analyses, bending tests and differential deposition experiments.

  17. Propagation of Optical Pulses in Polarization Maintaining Highly Birefringent Fibers

    NASA Astrophysics Data System (ADS)

    Leiva, Ariel; Olivares, Ricardo

    2008-04-01

    The propagation of Gaussian optical pulses through optical PM-HiBi (Polarization Maintaining Highly Birefringent) fibers is analyzed and simulated. Based upon a model of propagation as described by Marcuse, et al., [1] and Sunnerud, et al., [2], and the use of PMD (Polarization Mode Dispersion) compensators and emulators used by Kogelnik, et al. [2], [3] and Lima, et al. [4], we construct a simple model that allows graphical representation of the distortion experienced by optical pulses when propagating in a PM-HiBi fiber for different initial polarizations. The results of our analysis have the benefit of being identical to the more elaborate models of [1], [2], while also providing the additional advantage of simple graphical representation.

  18. Optical studies of high-temperature superconducting cuprates.

    PubMed

    Tajima, Setsuko

    2016-09-01

    The optical studies of high-temperature superconducting cuprates (HTSC) are reviewed. From the doping dependence of room temperature spectra, a dramatic change of the electronic state from a Mott (charge transfer) insulator to a Fermi liquid has been revealed. Additionally, the unusual 2D nature of the electronic state has been found. The temperature dependence of the optical spectra provided a rich source of information on the pseudogap, superconducting gap, Josephson plasmon, transverse Josephson plasma mode and precursory superconductivity. Among these issues, Josephson plasmons and transverse Josephson plasma mode were experimentally discovered by optical measurements, and thus are unique to HTSC. The effect of the spin/charge stripe order is also unique to HTSC, reflecting the conducting nature of the stripe order in this system. The pair-breaking due to the stripe order seems stronger in the out-of-plane direction than in the in-plane one. PMID:27472654

  19. Optical studies of high-temperature superconducting cuprates

    NASA Astrophysics Data System (ADS)

    Tajima, Setsuko

    2016-09-01

    The optical studies of high-temperature superconducting cuprates (HTSC) are reviewed. From the doping dependence of room temperature spectra, a dramatic change of the electronic state from a Mott (charge transfer) insulator to a Fermi liquid has been revealed. Additionally, the unusual 2D nature of the electronic state has been found. The temperature dependence of the optical spectra provided a rich source of information on the pseudogap, superconducting gap, Josephson plasmon, transverse Josephson plasma mode and precursory superconductivity. Among these issues, Josephson plasmons and transverse Josephson plasma mode were experimentally discovered by optical measurements, and thus are unique to HTSC. The effect of the spin/charge stripe order is also unique to HTSC, reflecting the conducting nature of the stripe order in this system. The pair-breaking due to the stripe order seems stronger in the out-of-plane direction than in the in-plane one.

  20. Coherent DWDM technology for high speed optical communications

    NASA Astrophysics Data System (ADS)

    Saunders, Ross

    2011-10-01

    The introduction of coherent digital optical transmission enables a new generation of high speed optical data transport and fiber impairment mitigation. An initial implementation of 40 Gb/s coherent systems using Dual Polarization Quadrature Phase Shift Keying (DP-QPSK) is already being installed in carrier networks. New systems running at 100 Gb/s DP-QPSK data rate are in development and early technology lab and field trial phase. Significant investment in the 100 Gb/s ecosystem (optical components, ASICs, transponders and systems) bodes well for commercial application in 2012 and beyond. Following in the footsteps of other telecommunications fields such as wireless and DSL, we can expect coherent optical transmission to evolve from QPSK to higher order modulations schemes such as Mary PSK and/or QAM. This will be an interesting area of research in coming years and poses significant challenges in terms of electro-optic, DSP, ADC/DAC design and fiber nonlinearity mitigation to reach practical implementation ready for real network deployments.

  1. Ultra-high resolution spectroscopy of optical frequency combs

    NASA Astrophysics Data System (ADS)

    Schneider, Thomas; Preußler, Stefan

    2016-03-01

    The precision, versatility and broad bandwidth of frequency combs are the basis of many different applications from the microwave via the millimeter and THz up to the optical range of the electromagnetic spectrum. Optical frequency combs can be used for the new definition of physical constants, for high-precision metrology and spectroscopy and for ultrahigh bitrate data communications, for instance. Besides the stability and the bandwidth, the most important parameters of a frequency comb are the free spectral range ,as well as the linewidth and amplitude of the single comb lines. A conventional grating based optical spectrometer can easily measure the bandwidth of the comb. However, it fails for the measurement of all other comb parameters, if the comb is generated by a mode-locked fiber laser for instance. Here we present a proof-of-concept setup for an optical spectrometer with a resolution in the kHz-range and first measurements of the free spectral range, linewidth and amplitude of a comb source. The spectrometer is based on the combination of optical heterodyning with the polarization pulling effect of stimulated Brillouin scattering. As we will discuss, the maximum possible resolution is only restricted by the linewidth and stability of the used reference laser. Thus due to the stability of our laser used as local oscillator, our setup has a maximum resolution of around 5 kHz or 40 attometer, corresponding to 11 orders of magnitude compared to the center frequency of the comb of around 190 THz.

  2. Active phase compensation system for fiber optic holography

    NASA Technical Reports Server (NTRS)

    Mercer, Carolyn R.; Beheim, Glenn

    1988-01-01

    Fiber optic delivery systems promise to extend the application of holography to severe environments by simplifying test configurations and permitting the laser to be remotely placed in a more benign location. However, the introduction of optical fiber leads to phase stability problems. Environmental effects cause the pathlengths of the fibers to change randomly, preventing the formation of stationary interference patterns which are required for holography. An active phase control system has been designed and used with an all-fiber optical system to stabilize the phase difference between light emitted from two fibers, and to step the phase difference by 90 deg without applying any constraints on the placement of the fibers. The accuracy of the phase steps is shown to be better than 0.02 deg., and a stable phase difference can be maintained for 30 min. This system can be applied to both conventional and electro-optic holography, as well as to any system where the maintenance of an accurate phase difference between two coherent beams is required.

  3. High magneto-optical characteristics of Holmium-doped terbium gallium garnet crystal.

    PubMed

    Chen, Zhe; Yang, Lei; Wang, Xiangyong; Yin, Hang

    2016-06-01

    Magneto-optical characteristics of a new magneto-active material, (Tb(1-x)Hox)3Ga5O12 crystal, have been grown by the Czochralski (Cz) method. A high value of the Verdet constant was obtained at room temperature-namely, 214.9 and 77.8  rad·m-1 T-1 for 632.8 and 1064 nm, respectively. The Verdet constant of the Ho-doped terbium gallium garnet crystal at 1064 nm is about 2 times higher than that of terbium gallium garnet crystal. High value of magneto-optical figure-of-merit makes it an attractive next-generation magneto-optics material for high-power Faraday isolators.

  4. High magneto-optical characteristics of Holmium-doped terbium gallium garnet crystal.

    PubMed

    Chen, Zhe; Yang, Lei; Wang, Xiangyong; Yin, Hang

    2016-06-01

    Magneto-optical characteristics of a new magneto-active material, (Tb(1-x)Hox)3Ga5O12 crystal, have been grown by the Czochralski (Cz) method. A high value of the Verdet constant was obtained at room temperature-namely, 214.9 and 77.8  rad·m-1 T-1 for 632.8 and 1064 nm, respectively. The Verdet constant of the Ho-doped terbium gallium garnet crystal at 1064 nm is about 2 times higher than that of terbium gallium garnet crystal. High value of magneto-optical figure-of-merit makes it an attractive next-generation magneto-optics material for high-power Faraday isolators. PMID:27244419

  5. Special issue on high-resolution optical imaging

    NASA Astrophysics Data System (ADS)

    Smith, Peter J. S.; Davis, Ilan; Galbraith, Catherine G.; Stemmer, Andreas

    2013-09-01

    The pace of development in the field of advanced microscopy is truly breath-taking, and is leading to major breakthroughs in our understanding of molecular machines and cell function. This special issue of Journal of Optics draws attention to a number of interesting approaches, ranging from fluorescence and imaging of unlabelled cells, to computational methods, all of which are describing the ever increasing detail of the dynamic behaviour of molecules in the living cell. This is a field which traditionally, and currently, demonstrates a marvellous interplay between the disciplines of physics, chemistry and biology, where apparent boundaries to resolution dissolve and living cells are viewed in ever more clarity. It is fertile ground for those interested in optics and non-conventional imaging to contribute high-impact outputs in the fields of cell biology and biomedicine. The series of articles presented here has been selected to demonstrate this interdisciplinarity and to encourage all those with a background in the physical sciences to 'dip their toes' into the exciting and dynamic discoveries surrounding cell function. Although single molecule super-resolution microscopy is commercially available, specimen preparation and interpretation of single molecule data remain a major challenge for scientists wanting to adopt the techniques. The paper by Allen and Davidson [1] provides a much needed detailed introduction to the practical aspects of stochastic optical reconstruction microscopy, including sample preparation, image acquisition and image analysis, as well as a brief description of the different variants of single molecule localization microscopy. Since super-resolution microscopy is no longer restricted to three-dimensional imaging of fixed samples, the review by Fiolka [2] is a timely introduction to techniques that have been successfully applied to four-dimensional live cell super-resolution microscopy. The combination of multiple high-resolution techniques

  6. High dynamic range optical projection tomography (HDR-OPT).

    PubMed

    Fei, Peng; Yu, Zhilong; Wang, Xu; Lu, Peter J; Fu, Yusi; He, Zi; Xiong, Jingwei; Huang, Yanyi

    2012-04-01

    Traditional optical projection tomography (OPT) acquires a single image at each rotation angle, thereby suffering from limitations in CCD dynamic range; this conventional usage cannot resolve features in samples with highly heterogeneous absorption, such as in small animals with organs of varying size. We present a novel technique, applying multiple-exposure high dynamic range (HDR) imaging to OPT, and demonstrate its ability to resolve fine details in zebrafish embryos, without complicated chemical clearing. We implement the tomographic reconstruction algorithm on the GPU, yielding a performance increase of two orders of magnitude. These features give our method potential application in high-throughput, high-resolution in vivo 3D imaging.

  7. Investigations of electron helicity in optically active molecules using polarized beams of electrons and positrons

    NASA Technical Reports Server (NTRS)

    Gidley, D. W.; Rich, A.; Van House, J. C.; Zitzewitz, P. W.

    1981-01-01

    A positronium-formation experiment with a high sensitivity to a possible relation between the helicity of beta particles emitted in nuclear beta decay and the optical asymmetry of biological molecules is presented. The experiment is based on a mechanism in which the electrons in optically active molecules possess a helicity of less than 0.001, too weak to detect in radiolysis experiments, the sign of which depends on the chirality of the isomer. A helicity-dependent asymmetry is sought in the formation of the triplet ground state of positronium when a low-energy beam of polarized positrons of reversible helicity interacts with an optically active substance coating a channel electron multiplier. Asymmetries between positronium decays observed at positive and negative helicities for the same substance can thus be determined with a sensitivity of 0.0001, which represents a factor of 100 improvement over previous positronium experiments.

  8. Near-Field Optical Recording Using Solid Immersion Lens for High-Density Flexible Optical Disks

    NASA Astrophysics Data System (ADS)

    Koide, Daiichi; Kajiyama, Takeshi; Sato, Ryuji; Tokumaru, Haruki; Takano, Yoshimichi; Ohishi, Kiyoshi

    2013-09-01

    We propose a near-field optical recording flexible optical disk (NFR-FOD) for high-density recording at a high data transfer rate. We built a prototype high-density NFR-FOD that had a track pitch of 0.16 µm and we stacked some recording layers on a thin substrate that was 0.1 mm thick. We rotated the NFR-FOD closing the mechanical stabilizer on a drive system with less than 10 µmp-p axial run-out and achieved precise gap servo operation at a high rotational speed. We demonstrated near-field optical recording with a solid immersion lens with a numerical aperture (NA) of 1.84 on the NFR-FOD. The NFR-FOD has a fourfold higher recording density than the current Blu-ray disc, corresponding to a capacity of 100 Gbytes per layer, and a high data transfer rate of 250 Mbps, while rotating at half the speed.

  9. Using optical dating to assess the recent activity of active faults in Hsinchu Area, northwestern Taiwan

    NASA Astrophysics Data System (ADS)

    Watanuki, T.; Chen, Y.

    2003-12-01

    The aim of this study is to evaluate the recent activity of active fault systems mapped in Hsinchu area, northwestern Taiwan. Since it is the largest site of industrial park and highly populated, it is essential to assess potential of earthquake hazards. As a result of previous work, two active fault systems (Hsinchu and Hsincheng) were identified as active. However, they have not been included in dangerous active faults on published map because Holocene offset has not been confirmed yet. Relationship between five river terraces and faults were discussed by mapping on geomorphic features; both of these thrust faults contain active anticlines in their hanging walls based on folded terraces that are composed of young alluvial deposits. Neither long-term nor short-term slip rate has been reported due to lack of age control on development timing of the terraces mentioned above. We collected samples from these terraces and open-pit trench on the highest terrace, where intercalated sandy layers are found within cobbles. As literatures optically stimulated luminescence (OSL) dating method can directly measure the burial ages of sedimentary deposits that underwent a short period of sunlight bleaching. Therefore, OSL dating is applied via single aliquot regeneration method on sand size quartz extract from our study terraces. OSL ages about 46ka and 68-75ka are obtained from 4 fluvial deposits at trenching site. We tentatively suggest that the terrace was abandoned by the main channel after 68ka and then upper strata were subsequently deposited by local small creeks. The vertical displacements cross these Hsinchu and Hsincheng active faults are ca. 90m and 70m, respectively since 68ka. Consequently, the derived long-term rates of vertical slip are 1.3 and 1.0 m/ka respectively for both of them. The details of the other age results and discussion on recent structural behavior will be presented.

  10. High-irradiance reactors with unfolded aplanatic optics.

    PubMed

    Feuermann, Daniel; Gordon, Jeffrey M

    2008-11-01

    Reconstituting the intense irradiance of short-arc discharge lamps at a remote target, at high radiative efficiency, represents a central challenge in the design of high-temperature chemical reactors, heightened by the need for high numerical aperture at both the target and the source. Separating the optical system from both the source and the reactor allows pragmatic operation, monitoring, and control. We explore near-field unfolded aplanats as feasible solutions and report measurements for a prototype that constitutes a double-ellipsoid mirror. We also propose compound unfolded aplanats that collect lamp emission over all angles (in lieu of light recycling optics) and irradiate the reactor over nearly its full circumference.

  11. High-Resolution Imaging of the Optic Nerve and Retina in Optic Nerve Hypoplasia

    PubMed Central

    Pilat, Anastasia; Sibley, Daniel; McLean, Rebecca J.; Proudlock, Frank A.; Gottlob, Irene

    2015-01-01

    Purpose To investigate the optic nerve and macular morphology in patients with optic nerve hypoplasia (ONH) using spectral-domain optical coherence tomography (SD OCT). Design Prospective, cross-sectional, observational study. Subjects A total of 16 participants with ONH (10 female and 6 male; mean age, 17.2 years; 6 bilateral involvement) and 32 gender-, age-, ethnicity-, and refraction-matched healthy controls. Methods High-resolution SD OCT (Copernicus [Optopol Technology S.A., Zawiercie, Poland], 3 μm resolution) and handheld SD OCT (Bioptigen Inc [Research Triangle Park, NC], 2.6 μm resolution) devices were used to acquire horizontal scans through the center of the optic disc and macula. Main Outcome Measures Horizontal optic disc/cup and rim diameters, cup depth, peripapillary retinal nerve fiber layer (RNFL), and thickness of individual retinal layers in participants with ONH and in controls. Results Patients with ONH had significantly smaller discs (P < 0.03 and P < 0.001 compared with unaffected eye and healthy controls, respectively), horizontal cup diameter (P < 0.02 for both), and cup depth (P < 0.02 and P < 0.01, respectively). In the macula, significantly thinner RNFL (nasally), ganglion cell layer (GCL) (nasally and temporally), inner plexiform layer (IPL) (nasally), outer nuclear layer (ONL) (nasally), and inner segment (centrally and temporally) were found in patients with ONH compared with the control group (P < 0.05 for all comparisons). Continuation of significantly thicker GCL, IPL, and outer plexiform layer in the central retinal area (i.e., foveal hypoplasia) was found in more than 80% of patients with ONH. Clinically unaffected fellow eyes of patients with ONH showed mild features of underdevelopment. Visual acuity and presence of septo-optic dysplasia were associated with changes in GCL and IPL. Sensitivity and specificity for the detection of ONH based on disc and retinal optical coherence tomography (OCT) parameters were >80

  12. Optical Histology: High-Resolution Visualization of Tissue Microvasculature

    NASA Astrophysics Data System (ADS)

    Moy, Austin Jing-Ming

    Mammalian tissue requires the delivery of nutrients, growth factors, and the exchange of oxygen and carbon dioxide gases to maintain normal function. These elements are delivered by the blood, which travels through the connected network of blood vessels, known as the vascular system. The vascular system consists of large feeder blood vessels (arteries and veins) that are connected to the small blood vessels (arterioles and venules), which in turn are connected to the capillaries that are directly connected to the tissue and facilitate gas exchange and nutrient delivery. These small blood vessels and capillaries make up an intricate but organized network of blood vessels that exist in all mammalian tissues known as the microvasculature and are very important in maintaining the health and proper function of mammalian tissue. Due to the importance of the microvasculature in tissue survival, disruption of the microvasculature typically leads to tissue dysfunction and tissue death. The most prevalent method to study the microvasculature is visualization. Immunohistochemistry (IHC) is the gold-standard method to visualize tissue microvasculature. IHC is very well-suited for highly detailed interrogation of the tissue microvasculature at the cellular level but is unwieldy and impractical for wide-field visualization of the tissue microvasculature. The objective my dissertation research was to develop a method to enable wide-field visualization of the microvasculature, while still retaining the high-resolution afforded by optical microscopy. My efforts led to the development of a technique dubbed "optical histology" that combines chemical and optical methods to enable high-resolution visualization of the microvasculature. The development of the technique first involved preliminary studies to quantify optical property changes in optically cleared tissues, followed by development and demonstration of the methodology. Using optical histology, I successfully obtained high

  13. Sparse matrix approximation method for an active optical control system

    NASA Astrophysics Data System (ADS)

    Murphy, Timothy P.; Lyon, Richard G.; Dorband, John E.; Hollis, Jan M.

    2001-12-01

    We develop a sparse matrix approximation method to decompose a wave front into a basis set of actuator influence functions for an active optical system consisting of a deformable mirror and a segmented primary mirror. The wave front used is constructed by Zernike polynomials to simulate the output of a phase-retrieval algorithm. Results of a Monte Carlo simulation of the optical control loop are compared with the standard, nonsparse approach in terms of accuracy and precision, as well as computational speed and memory. The sparse matrix approximation method can yield more than a 50-fold increase in the speed and a 20-fold-reduction in matrix size and a commensurate decrease in required memory, with less than 10% degradation in solution accuracy. Our method is also shown to be better than when elements are selected for the sparse matrix on a magnitude basis alone. We show that the method developed is a viable alternative to use of the full control matrix in a phase-retrieval-based active optical control system.

  14. Sparse matrix approximation method for an active optical control system.

    PubMed

    Murphy, T P; Lyon, R G; Dorband, J E; Hollis, J M

    2001-12-10

    We develop a sparse matrix approximation method to decompose a wave front into a basis set of actuator influence functions for an active optical system consisting of a deformable mirror and a segmented primary mirror. The wave front used is constructed by Zernike polynomials to simulate the output of a phase-retrieval algorithm. Results of a Monte Carlo simulation of the optical control loop are compared with the standard, nonsparse approach in terms of accuracy and precision, as well as computational speed and memory. The sparse matrix approximation method can yield more than a 50-fold increase in the speed and a 20-fold reduction in matrix size and a commensurate decrease in required memory, with less than 10% degradation in solution accuracy. Our method is also shown to be better than when elements are selected for the sparse matrix on a magnitude basis alone. We show that the method developed is a viable alternative to use of the full control matrix in a phase-retrieval-based active optical control system. PMID:18364958

  15. Chiral magnetic effect and natural optical activity in (Weyl) metals

    NASA Astrophysics Data System (ADS)

    Pesin, Dmytro; Ma, Jing

    We consider the phenomenon of natural optical activity, and related chiral magnetic effect in metals with low carrier concentration. To reveal the correspondence between the two phenomena, we compute the optical conductivity of a noncentrosymmetric metal to linear order in the wave vector of the light wave, specializing to the low-frequency regime. We show that it is the orbital magnetic moment of quasiparticles that is responsible for the natural optical activity, and thus the chiral magnetic effect. While for purely static magnetic fields the chiral magnetic effect is known to have a topological origin and to be related to the presence of Berry curvature monopoles (Weyl points) in the band structure, we show that the existence of Berry monopoles is not required for the dynamic chiral magnetic effect to appear; the latter is thus not unique to Weyl metals. The magnitude of the dynamic chiral magnetic effect in a material is related to the trace of its gyrotropic tensor. We discuss the conditions under which this trace is non-zero; in noncentrosymmetric Weyl metals it is found to be proportional to the energy-space dipole moment of Berry curvature monopoles. The calculations are done within both the semiclassical kinetic equation, and Kubo linear response formalisms. This work was supported by NSF Grant No. DMR-1409089.

  16. Large-aperture active optical carbon fiber reinforced polymer mirror

    NASA Astrophysics Data System (ADS)

    Jungwirth, Matthew E. L.; Wilcox, Christopher C.; Wick, David V.; Baker, Michael S.; Hobart, Clinton G.; Milinazzo, Jared J.; Robichaud, Joseph; Romeo, Robert C.; Martin, Robert N.; Ballesta, Jerome; Lavergne, Emeric; Dereniak, Eustace L.

    2013-05-01

    An active reflective component can change its focal length by physically deforming its reflecting surface. Such elements exist at small apertures, but have yet to be fully realized at larger apertures. This paper presents the design and initial results of a large-aperture active mirror constructed of a composite material called carbon fiber reinforced polymer (CFRP). The active CFRP mirror uses a novel actuation method to change radius of curvature, where actuators press against two annular rings placed on the mirror's back. This method enables the radius of curvature to increase from 2000mm to 2010mm. Closed-loop control maintains good optical performance of 1.05 waves peak-to-valley (with respect to a HeNe laser) when the active CFRP mirror is used in conjunction with a commercial deformable mirror.

  17. Active Figure Control Effects on Mounting Strategy for X-Ray Optics

    NASA Technical Reports Server (NTRS)

    Kolodziejczak, Jeffery J.; Atkins, Carolyn; Roche, Jacqueline M.; ODell, Stephen L.; Ramsey, Brian D.; Elsner, Ronald F.; Weisskopf, Martin C.; Gubarev, Mikhail V.

    2014-01-01

    As part of ongoing development efforts at MSFC, we have begun to investigate mounting strategies for highly nested xray optics in both full-shell and segmented configurations. The analytical infrastructure for this effort also lends itself to investigation of active strategies. We expect that a consequence of active figure control on relatively thin substrates is that errors are propagated to the edges, where they might affect the effective precision of the mounting points. Based upon modeling, we describe parametrically, the conditions under which active mounts are preferred over fixed ones, and the effect of active figure corrections on the required number, locations, and kinematic characteristics of mounting points.

  18. Analysis of Active Figure Control Effects on Mounting Strategy for X-Ray Optics

    NASA Technical Reports Server (NTRS)

    Kolodziejczak, Jeffrey J.; Roche, Jacqueline M.; O'Dell, Stephen L.; Ramsey, Brian D.; Elsner, Ryan F.; Gubarev, Mikhail V.; Weisskopf, Martin C.

    2014-01-01

    As part of ongoing development efforts at MSFC, we have begun to investigate mounting strategies for highly nested x-ray optics in both full-shell and segmented configurations. The analytical infrastructure for this effort also lends itself to investigation of active strategies. We expect that a consequence of active figure control on relatively thin substrates is that errors are propagated to the edges, where they might affect the effective precision of the mounting points. Based upon modeling, we describe parametrically, the conditions under which active mounts are preferred over fixed ones, and the effect of active figure corrections on the required number, locations, and kinematic characteristics of mounting points.

  19. Active eye-tracking for an adaptive optics scanning laser ophthalmoscope.

    PubMed

    Sheehy, Christy K; Tiruveedhula, Pavan; Sabesan, Ramkumar; Roorda, Austin

    2015-07-01

    We demonstrate a system that combines a tracking scanning laser ophthalmoscope (TSLO) and an adaptive optics scanning laser ophthalmoscope (AOSLO) system resulting in both optical (hardware) and digital (software) eye-tracking capabilities. The hybrid system employs the TSLO for active eye-tracking at a rate up to 960 Hz for real-time stabilization of the AOSLO system. AOSLO videos with active eye-tracking signals showed, at most, an amplitude of motion of 0.20 arcminutes for horizontal motion and 0.14 arcminutes for vertical motion. Subsequent real-time digital stabilization limited residual motion to an average of only 0.06 arcminutes (a 95% reduction). By correcting for high amplitude, low frequency drifts of the eye, the active TSLO eye-tracking system enabled the AOSLO system to capture high-resolution retinal images over a larger range of motion than previously possible with just the AOSLO imaging system alone.

  20. A thin film active-lens with translational control for dynamically programmable optical zoom

    NASA Astrophysics Data System (ADS)

    Yun, Sungryul; Park, Suntak; Park, Bongje; Nam, Saekwang; Park, Seung Koo; Kyung, Ki-Uk

    2015-08-01

    We demonstrate a thin film active-lens for rapidly and dynamically controllable optical zoom. The active-lens is composed of a convex hemispherical polydimethylsiloxane (PDMS) lens structure working as an aperture and a dielectric elastomer (DE) membrane actuator, which is a combination of a thin DE layer made with PDMS and a compliant electrode pattern using silver-nanowires. The active-lens is capable of dynamically changing focal point of the soft aperture as high as 18.4% through its translational movement in vertical direction responding to electrically induced bulged-up deformation of the DE membrane actuator. Under operation with various sinusoidal voltage signals, the movement responses are fairly consistent with those estimated from numerical simulation. The responses are not only fast, fairly reversible, and highly durable during continuous cyclic operations, but also large enough to impart dynamic focus tunability for optical zoom in microscopic imaging devices with a light-weight and ultra-slim configuration.

  1. Active eye-tracking for an adaptive optics scanning laser ophthalmoscope

    PubMed Central

    Sheehy, Christy K.; Tiruveedhula, Pavan; Sabesan, Ramkumar; Roorda, Austin

    2015-01-01

    We demonstrate a system that combines a tracking scanning laser ophthalmoscope (TSLO) and an adaptive optics scanning laser ophthalmoscope (AOSLO) system resulting in both optical (hardware) and digital (software) eye-tracking capabilities. The hybrid system employs the TSLO for active eye-tracking at a rate up to 960 Hz for real-time stabilization of the AOSLO system. AOSLO videos with active eye-tracking signals showed, at most, an amplitude of motion of 0.20 arcminutes for horizontal motion and 0.14 arcminutes for vertical motion. Subsequent real-time digital stabilization limited residual motion to an average of only 0.06 arcminutes (a 95% reduction). By correcting for high amplitude, low frequency drifts of the eye, the active TSLO eye-tracking system enabled the AOSLO system to capture high-resolution retinal images over a larger range of motion than previously possible with just the AOSLO imaging system alone. PMID:26203370

  2. Noncontact measurement of high temperature using optical fiber sensors

    NASA Technical Reports Server (NTRS)

    Claus, R. O.

    1990-01-01

    The primary goal of this research program was the investigation and application of noncontact temperature measurement techniques using optical techniques and optical fiber methods. In particular, a pyrometer utilizing an infrared optical light pipe and a multiwavelength filtering approach was designed, revised, and tested. This work was motivated by the need to measure the temperatures of small metallic pellets (approximately 3 mm diameter) in free fall at the Microgravity Materials Processing Drop Tube at NASA Marshall Space Flight Center. In addition, research under this program investigated the adaptation of holography technology to optical fiber sensors, and also examined the use of rare-earth dopants in optical fibers for use in measuring temperature. The pyrometer development effort involved both theoretical analysis and experimental tests. For the analysis, a mathematical model based on radiative transfer principles was derived. Key parameter values representative of the drop tube system, such as particle size, tube diameter and length, and particle temperature, were used to determine an estimate of the radiant flux that will be incident on the face of an optical fiber or light pipe used to collect radiation from the incandescent falling particle. An extension of this work examined the advantage of inclining or tilting the collecting fiber to increase the time that the falling particle remains in the fiber field-of-view. Those results indicate that increases in total power collected of about 15 percent may be realized by tilting the fiber. In order to determine the suitability of alternative light pipes and optical fibers, and experimental set-up for measuring the transmittance and insertion loss of infrared fibers considered for use in the pyrometer was assembled. A zirconium fluoride optical fiber and several bundles of hollow core fiber of varying diameters were tested. A prototype two-color pyrometer was assembled and tested at Virginia Tech, and then

  3. Extremely aspheric mirrors: prototype development of an innovative manufacturing process based on active optics

    NASA Astrophysics Data System (ADS)

    Challita, Zalpha; Hugot, Emmanuel; Ferrari, Marc; Le Merrer, Joël.; Le Mignant, David; Cuby, Jean-Gabriel

    2012-09-01

    The next generation of focal-plane astronomical instruments requires technological breakthroughs to reduce their system complexity while increasing their scientific performances. Applied to the optical systems, recent studies show that the use of freeform reflective optics allows competitive compact systems with less optical components. In this context, our challenge is to supply an active freeform mirror system, using a combination of different active optics techniques. The optical shape will be provided during the fabrication using the mechanical property of metals to plasticize and will be coupled with a specific actuator system to compensate for the residual form errors, during the instrument operation phase. We present in this article the development of an innovative manufacturing process based on cold hydro-forming method, with the aim to adapt it for VIS/NIR requirements in terms of optical surface quality. It can operate on thin and flat polished initial substrates. The realization of a first prototype for a 100 mm optical diameter mirror is in progress, to compare the mechanical behaviours obtained by tests and by Finite Element Analysis (FEA), for different materials. Then, the formed samples will be characterized optically. The opto-mechanical results will allow a fine tuning of FEA parameters to optimize the residual form errors obtained through this process. It concerns the microstructure considerations, the springback effects and the work hardening evolutions of the samples, depending on the initial substrate properties and the boundary conditions applied. Modeling and tests have started with axi-symmetric spherical and aspherical shapes and will continue with highly aspherics and freeforms.

  4. High Resolution Optical and NIR Spectra of HBC 722

    NASA Astrophysics Data System (ADS)

    Lee, Jeong-Eun; Park, Sunkyung; Green, Joel D.; Cochran, William D.; Kang, Wonseok; Lee, Sang-Gak; Sung, Hyun-Il

    2015-07-01

    We present the results of high resolution (R ≥ 30,000) optical and near-IR spectroscopic monitoring observations of HBC 722, a recent FU Orionis object that underwent an accretion burst in 2010. We observed HBC 722 in the optical/near-IR with the Bohyunsan Optical Echelle Spectrograph, Hobby–Eberly Telescope-HRS, and Immersion Grating Infrared Spectrograph, at various points in the outburst. We found atomic lines with strongly blueshifted absorption features or P Cygni profiles, both evidence of a wind driven by the accretion. Some lines show a broad double-peaked absorption feature, evidence of disk rotation. However, the wind-driven and disk-driven spectroscopic features are anti-correlated in time; the disk features became strong as the wind features disappeared. This anti-correlation might indicate that the rebuilding of the inner disk was interrupted by the wind pressure during the first 2 years. The half-width at half-depth of the double-peaked profiles decreases with wavelength, indicative of the Keplerian rotation; the optical spectra with the disk feature are fitted by a G5 template stellar spectrum convolved with a rotation velocity of 70 km s‑1 while the near-IR disk features are fitted by a K5 template stellar spectrum convolved with a rotation velocity of 50 km s‑1. Therefore, the optical and near-IR spectra seem to trace the disk at 39 and 76 R⊙, respectively. We fit a power-law temperature distribution in the disk, finding an index of 0.8, comparable to optically thick accretion disk models. Based on observations obtained with the Hobby–Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen.

  5. HIGH RESOLUTION OPTICAL AND NIR SPECTRA OF HBC 722

    SciTech Connect

    Lee, Jeong-Eun; Park, Sunkyung; Green, Joel D.; Cochran, William D.; Kang, Wonseok; Lee, Sang-Gak; Sung, Hyun-Il E-mail: sunkyung@khu.ac.kr E-mail: wdc@astro.as.utexas.edu E-mail: sanggak@kywa.or.kr

    2015-07-01

    We present the results of high resolution (R ≥ 30,000) optical and near-IR spectroscopic monitoring observations of HBC 722, a recent FU Orionis object that underwent an accretion burst in 2010. We observed HBC 722 in the optical/near-IR with the Bohyunsan Optical Echelle Spectrograph, Hobby–Eberly Telescope-HRS, and Immersion Grating Infrared Spectrograph, at various points in the outburst. We found atomic lines with strongly blueshifted absorption features or P Cygni profiles, both evidence of a wind driven by the accretion. Some lines show a broad double-peaked absorption feature, evidence of disk rotation. However, the wind-driven and disk-driven spectroscopic features are anti-correlated in time; the disk features became strong as the wind features disappeared. This anti-correlation might indicate that the rebuilding of the inner disk was interrupted by the wind pressure during the first 2 years. The half-width at half-depth of the double-peaked profiles decreases with wavelength, indicative of the Keplerian rotation; the optical spectra with the disk feature are fitted by a G5 template stellar spectrum convolved with a rotation velocity of 70 km s{sup −1} while the near-IR disk features are fitted by a K5 template stellar spectrum convolved with a rotation velocity of 50 km s{sup −1}. Therefore, the optical and near-IR spectra seem to trace the disk at 39 and 76 R{sub ⊙}, respectively. We fit a power-law temperature distribution in the disk, finding an index of 0.8, comparable to optically thick accretion disk models.

  6. High Resolution Optical and NIR Spectra of HBC 722

    NASA Astrophysics Data System (ADS)

    Lee, Jeong-Eun; Park, Sunkyung; Green, Joel D.; Cochran, William D.; Kang, Wonseok; Lee, Sang-Gak; Sung, Hyun-Il

    2015-07-01

    We present the results of high resolution (R ≥ 30,000) optical and near-IR spectroscopic monitoring observations of HBC 722, a recent FU Orionis object that underwent an accretion burst in 2010. We observed HBC 722 in the optical/near-IR with the Bohyunsan Optical Echelle Spectrograph, Hobby-Eberly Telescope-HRS, and Immersion Grating Infrared Spectrograph, at various points in the outburst. We found atomic lines with strongly blueshifted absorption features or P Cygni profiles, both evidence of a wind driven by the accretion. Some lines show a broad double-peaked absorption feature, evidence of disk rotation. However, the wind-driven and disk-driven spectroscopic features are anti-correlated in time; the disk features became strong as the wind features disappeared. This anti-correlation might indicate that the rebuilding of the inner disk was interrupted by the wind pressure during the first 2 years. The half-width at half-depth of the double-peaked profiles decreases with wavelength, indicative of the Keplerian rotation; the optical spectra with the disk feature are fitted by a G5 template stellar spectrum convolved with a rotation velocity of 70 km s-1 while the near-IR disk features are fitted by a K5 template stellar spectrum convolved with a rotation velocity of 50 km s-1. Therefore, the optical and near-IR spectra seem to trace the disk at 39 and 76 R⊙, respectively. We fit a power-law temperature distribution in the disk, finding an index of 0.8, comparable to optically thick accretion disk models. Based on observations obtained with the Hobby-Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen.

  7. Magnetic bearings for a high-performance optical disk buffer

    NASA Technical Reports Server (NTRS)

    Hockney, Richard; Hawkey, Timothy

    1993-01-01

    An optical disk buffer concept can provide gigabit-per-second data rates and terabit capacity through the use of arrays of solid state lasers applied to a stack of erasable/reusable optical disks. The RCA optical disk buffer has evoked interest by NASA for space applications. The porous graphite air bearings in the rotary spindle as well as those used in the linear translation of the read/write head would be replaced by magnetic bearings or mechanical (ball or roller) bearings. Based upon past experience, roller or ball bearings for the translation stages are not feasible. Unsatisfactory, although limited experience exists with ball bearing spindles also. Magnetic bearings, however, appear ideally suited for both applications. The use of magnetic bearings is advantageous in the optical disk buffer because of the absence of physical contact between the rotating and stationary members. This frictionless operation leads to extended life and reduced drag. The manufacturing tolerances that are required to fabricate magnetic bearings would also be relaxed from those required for precision ball and gas bearings. Since magnetic bearings require no lubricant, they are inherently compatible with a space (vacuum) environment. Magnetic bearings also allow the dynamics of the rotor/bearing system to be altered through the use of active control. This provides the potential for reduced vibration, extended regions of stable operation, and more precise control of position.

  8. Active Optics for a Segmented Primary Mirror on a Deep-Space Optical Receiver Antenna (DSORA)

    NASA Technical Reports Server (NTRS)

    Clymer, B. D.

    1990-01-01

    This article investigates the active optical control of segments in the primary mirror to correct for wavefront errors in the Deep-Space Optical Receiver Antenna (DSORA). Although an exact assessment of improvement in signal blur radius cannot be made until a more detailed preliminary structural design is completed, analytical tools are identified for a time when such designs become available. A brief survey of appropriate sensing approaches is given. Since the choice of control algorithm and architecture depends on the particular sensing system used, typical control systems, estimated complexities, and the type of equipment required are discussed. Once specific sensor and actuator systems are chosen, the overall control system can be optimized using methods identified in the literature.

  9. Adaptive optics with pupil tracking for high resolution retinal imaging.

    PubMed

    Sahin, Betul; Lamory, Barbara; Levecq, Xavier; Harms, Fabrice; Dainty, Chris

    2012-02-01

    Adaptive optics, when integrated into retinal imaging systems, compensates for rapidly changing ocular aberrations in real time and results in improved high resolution images that reveal the photoreceptor mosaic. Imaging the retina at high resolution has numerous potential medical applications, and yet for the development of commercial products that can be used in the clinic, the complexity and high cost of the present research systems have to be addressed. We present a new method to control the deformable mirror in real time based on pupil tracking measurements which uses the default camera for the alignment of the eye in the retinal imaging system and requires no extra cost or hardware. We also present the first experiments done with a compact adaptive optics flood illumination fundus camera where it was possible to compensate for the higher order aberrations of a moving model eye and in vivo in real time based on pupil tracking measurements, without the real time contribution of a wavefront sensor. As an outcome of this research, we showed that pupil tracking can be effectively used as a low cost and practical adaptive optics tool for high resolution retinal imaging because eye movements constitute an important part of the ocular wavefront dynamics.

  10. Optical Control of Living Cells Electrical Activity by Conjugated Polymers.

    PubMed

    Martino, Nicola; Bossio, Caterina; Vaquero Morata, Susana; Lanzani, Guglielmo; Antognazza, Maria Rosa

    2016-01-28

    Hybrid interfaces between organic semiconductors and living tissues represent a new tool for in-vitro and in-vivo applications. In particular, conjugated polymers display several optimal properties as substrates for biological systems, such as good biocompatibility, excellent mechanical properties, cheap and easy processing technology, and possibility of deposition on light, thin and flexible substrates. These materials have been employed for cellular interfaces like neural probes, transistors for excitation and recording of neural activity, biosensors and actuators for drug release. Recent experiments have also demonstrated the possibility to use conjugated polymers for all-optical modulation of the electrical activity of cells. Several in-vitro study cases have been reported, including primary neuronal networks, astrocytes and secondary line cells. Moreover, signal photo-transduction mediated by organic polymers has been shown to restore light sensitivity in degenerated retinas, suggesting that these devices may be used for artificial retinal prosthesis in the future. All in all, light sensitive conjugated polymers represent a new approach for optical modulation of cellular activity. In this work, all the steps required to fabricate a bio-polymer interface for optical excitation of living cells are described. The function of the active interface is to transduce the light stimulus into a modulation of the cell membrane potential. As a study case, useful for in-vitro studies, a polythiophene thin film is used as the functional, light absorbing layer, and Human Embryonic Kidney (HEK-293) cells are employed as the biological component of the interface. Practical examples of successful control of the cell membrane potential upon stimulation with light pulses of different duration are provided. In particular, it is shown that both depolarizing and hyperpolarizing effects on the cell membrane can be achieved depending on the duration of the light stimulus. The reported

  11. Polymer optical fiber grating as water activity sensor

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Webb, David J.

    2014-05-01

    Controlling the water content within a product has long been required in the chemical processing, agriculture, food storage, paper manufacturing, semiconductor, pharmaceutical and fuel industries. The limitations of water content measurement as an indicator of safety and quality are attributed to differences in the strength with which water associates with other components in the product. Water activity indicates how tightly water is "bound," structurally or chemically, in products. Water absorption introduces changes in the volume and refractive index of poly(methyl methacrylate) PMMA. Therefore for a grating made in PMMA based optical fiber, its wavelength is an indicator of water absorption and PMMA thus can be used as a water activity sensor. In this work we have investigated the performance of a PMMA based optical fiber grating as a water activity sensor in sugar solution, saline solution and Jet A-1 aviation fuel. Samples of sugar solution with sugar concentration from 0 to 8%, saline solution with concentration from 0 to 22%, and dried (10ppm), ambient (39ppm) and wet (68ppm) aviation fuels were used in experiments. The corresponding water activities are measured as 1.0 to 0.99 for sugar solution, 1.0 to 0.86 for saline solution, and 0.15, 0.57 and 1.0 for the aviation fuel samples. The water content in the measured samples ranges from 100% (pure water) to 10 ppm (dried aviation fuel). The PMMA based optical fiber grating exhibits good sensitivity and consistent response, and Bragg wavelength shifts as large as 3.4 nm when the sensor is transferred from dry fuel to wet fuel.

  12. Optical Control of Living Cells Electrical Activity by Conjugated Polymers.

    PubMed

    Martino, Nicola; Bossio, Caterina; Vaquero Morata, Susana; Lanzani, Guglielmo; Antognazza, Maria Rosa

    2016-01-01

    Hybrid interfaces between organic semiconductors and living tissues represent a new tool for in-vitro and in-vivo applications. In particular, conjugated polymers display several optimal properties as substrates for biological systems, such as good biocompatibility, excellent mechanical properties, cheap and easy processing technology, and possibility of deposition on light, thin and flexible substrates. These materials have been employed for cellular interfaces like neural probes, transistors for excitation and recording of neural activity, biosensors and actuators for drug release. Recent experiments have also demonstrated the possibility to use conjugated polymers for all-optical modulation of the electrical activity of cells. Several in-vitro study cases have been reported, including primary neuronal networks, astrocytes and secondary line cells. Moreover, signal photo-transduction mediated by organic polymers has been shown to restore light sensitivity in degenerated retinas, suggesting that these devices may be used for artificial retinal prosthesis in the future. All in all, light sensitive conjugated polymers represent a new approach for optical modulation of cellular activity. In this work, all the steps required to fabricate a bio-polymer interface for optical excitation of living cells are described. The function of the active interface is to transduce the light stimulus into a modulation of the cell membrane potential. As a study case, useful for in-vitro studies, a polythiophene thin film is used as the functional, light absorbing layer, and Human Embryonic Kidney (HEK-293) cells are employed as the biological component of the interface. Practical examples of successful control of the cell membrane potential upon stimulation with light pulses of different duration are provided. In particular, it is shown that both depolarizing and hyperpolarizing effects on the cell membrane can be achieved depending on the duration of the light stimulus. The reported

  13. Elevating optical activity: Efficient on-edge lithography of three-dimensional starfish metamaterial

    NASA Astrophysics Data System (ADS)

    Dietrich, K.; Menzel, C.; Lehr, D.; Puffky, O.; Hübner, U.; Pertsch, T.; Tünnermann, A.; Kley, E.-B.

    2014-05-01

    We present an approach for extremely fast, wafer-scale fabrication of chiral starfish metamaterials based on electron beam- and on-edge lithography. A millimeter sized array of both the planar chiral and the true 3D chiral starfish is realized, and their chiroptical performances are compared by circular dichroism measurements. We find optical activity in the visible and near-infrared spectral range, where the 3D starfish clearly outperforms the planar design by almost 2 orders of magnitude, though fabrication efforts are only moderately increased. The presented approach is capable of bridging the gap between high performance optical chiral metamaterials and industrial production by nanoimprint technology.

  14. Elevating optical activity: Efficient on-edge lithography of three-dimensional starfish metamaterial

    SciTech Connect

    Dietrich, K. Menzel, C.; Lehr, D.; Puffky, O.; Pertsch, T.; Tünnermann, A.; Kley, E.-B.; Hübner, U.

    2014-05-12

    We present an approach for extremely fast, wafer-scale fabrication of chiral starfish metamaterials based on electron beam- and on-edge lithography. A millimeter sized array of both the planar chiral and the true 3D chiral starfish is realized, and their chiroptical performances are compared by circular dichroism measurements. We find optical activity in the visible and near-infrared spectral range, where the 3D starfish clearly outperforms the planar design by almost 2 orders of magnitude, though fabrication efforts are only moderately increased. The presented approach is capable of bridging the gap between high performance optical chiral metamaterials and industrial production by nanoimprint technology.

  15. GFOC Project results: High Temperature / High Pressure, Hydrogen Tolerant Optical Fiber

    SciTech Connect

    E. Burov; A. Pastouret; E. Aldea; B. Overton; F. Gooijer; A. Bergonzo

    2012-02-12

    Tests results are given for exposure of multimode optical fiber to high temperatures (300 deg. C) and high partial pressure (15 bar) hydrogen. These results demonstrate that fluorine down doped optical fibers are much more hydrogen tolerant than traditional germanium doped multimode optical fibers. Also demonstrated is the similar hydrogen tolerance of carbon coated and non-carbon coated fibers. Model for reversible H2 impact in fiber versus T{sup o}C and H2 pressure is given. These results have significant impact for the longevity of use for distributed temperature sensing applications in harsh environments such as geothermal wells.

  16. High-speed Light Peak optical link for high energy applications

    NASA Astrophysics Data System (ADS)

    Chang, F. X.; Chiang, F.; Deng, B.; Hou, J.; Hou, S.; Liu, C.; Liu, T.; Teng, P. K.; Wang, C. H.; Xu, T.; Ye, J.

    2014-11-01

    Optical links provide high speed data transmission with low mass fibers favorable for applications in high energy experiments. We report investigation of a compact Light Peak optical engine designed for data transmission at 4.8 Gbps. The module is assembled with bare die VCSEL, PIN diodes and a control IC aligned within a prism receptacle for light coupling to fiber ferrule. Radiation damage in the receptacle was examined with 60Co gamma ray. Radiation induced single event effects in the optical engine were studied with protons, neutrons and X-ray tests.

  17. Optical performance monitoring in high-speed optical fiber communication systems

    NASA Astrophysics Data System (ADS)

    Yu, Changyuan; Yang, Jing; Hu, Junhao; Zhang, Banghong

    2011-11-01

    Optical performance monitoring (OPM) becomes an attractive topic as the rapid growth of data rate in optical communication networks. It provides improved operation of the high capacity optical transmission systems. Among the various impairments, chromatic dispersion (CD) is one of major factors limiting the transmission distance in high-speed communication systems. Polarization-mode dispersion (PMD) also becomes a degrading effect in the system with data rate larger than 40 Gbit/s. In this paper, we summarize several CD and PMD monitoring methods based on RF spectrum analysis and delay-tap sampling. By using a narrow band fiber Bragg grating (FBG) notch filter, centered at 10 GHz away from the optical carrier, 10-GHz RF power can be used as a CD-insensitive PMD monitoring signal. By taking the 10-GHz RF power ratio of non-filtered and filtered signal, PMD-insensitive CD monitoring can be achieved. If the FBG notch filter is placed at optical carrier, the RF clock power ratio between non-filtered and filtered signal is also a PMDinsensitive CD monitoring parameter, which has larger RF power dynamic range and better measurement resolution. Both simulation and experiment results show that the proposed methods are efficient on measuring CD and PMD values in 57-Gbit/s D8PSK systems. Delay-tap sampling is another efficient method of measuring residual CD. Amplitude ratio of asynchronous delay-tap sampling plot decreases with CD monotonously, and the amplitude ratio can be obtained by using low bandwidth balanced receiver. The simulated results show that our method is efficient on residual CD measurement in 50-Gbit/s 50% RZ DQPSK systems with a 12-GHz balanced receiver. Since no modification on the transmitter or receiver is required, the proposed scheme is simple and cost effective.

  18. High-Resolution CRT Optical Film Recorder Incorporating an Optical Feedback Exposure Control.

    PubMed

    Nix, L A; Ley, G S

    1972-05-01

    A high-resolution CRT optical film recorder incorporating an optical exposure control system is described. The recorder incorporates provisions for a highly nonlinear writing rate of up to 7 to 1 that make it uniquely suited for such applications as side-look radar or sonar. Provisions are made for spot shaping permitting line fill-in between scan lines spaced up to ten spot sizes apart. The recorder achieves a linear gray scale having sixteen equal density steps for a wide range of sweep times by means of a brightness feedback loop that automatically corrects for such problems as phosphor saturation, phosphor noise, nonlinear CRT grid transfer characteristics, variation in cathode emission, and tube aging in conjunction with film gamma correction circuitry.

  19. High specific activity silicon-32

    DOEpatents

    Phillips, Dennis R.; Brzezinski, Mark A.

    1996-01-01

    A process for preparation of silicon-32 is provided and includes contacting an irradiated potassium chloride target, including spallation products from a prior irradiation, with sufficient water, hydrochloric acid or potassium hydroxide to form a solution, filtering the solution, adjusting pH of the solution to from about 5.5 to about 7.5, admixing sufficient molybdate-reagent to the solution to adjust the pH of the solution to about 1.5 and to form a silicon-molybdate complex, contacting the solution including the silicon-molybdate complex with a dextran-based material, washing the dextran-based material to remove residual contaminants such as sodium-22, separating the silicon-molybdate complex from the dextran-based material as another solution, adding sufficient hydrochloric acid and hydrogen peroxide to the solution to prevent reformation of the silicon-molybdate complex and to yield an oxidization state of the molybdate adapted for subsequent separation by an anion exchange material, contacting the solution with an anion exchange material whereby the molybdate is retained by the anion exchange material and the silicon remains in solution, and optionally adding sufficient alkali metal hydroxide to adjust the pH of the solution to about 12 to 13. Additionally, a high specific activity silicon-32 product having a high purity is provided.

  20. High specific activity silicon-32

    DOEpatents

    Phillips, D.R.; Brzezinski, M.A.

    1996-06-11

    A process for preparation of silicon-32 is provided and includes contacting an irradiated potassium chloride target, including spallation products from a prior irradiation, with sufficient water, hydrochloric acid or potassium hydroxide to form a solution, filtering the solution, adjusting pH of the solution from about 5.5 to about 7.5, admixing sufficient molybdate-reagent to the solution to adjust the pH of the solution to about 1.5 and to form a silicon-molybdate complex, contacting the solution including the silicon-molybdate complex with a dextran-based material, washing the dextran-based material to remove residual contaminants such as sodium-22, separating the silicon-molybdate complex from the dextran-based material as another solution, adding sufficient hydrochloric acid and hydrogen peroxide to the solution to prevent reformation of the silicon-molybdate complex and to yield an oxidation state of the molybdate adapted for subsequent separation by an anion exchange material, contacting the solution with an anion exchange material whereby the molybdate is retained by the anion exchange material and the silicon remains in solution, and optionally adding sufficient alkali metal hydroxide to adjust the pH of the solution to about 12 to 13. Additionally, a high specific activity silicon-32 product having a high purity is provided.

  1. Multiserver switch scheduling for high speed optical switches

    NASA Astrophysics Data System (ADS)

    Golla, Prasad; Blanton, John; Damm, Gerard

    2003-10-01

    A switch matrix implemented as an optical crossbar using semiconductor optical amplifiers is able to accommodate extreme concentrations of data traffic. Due to the need to reduce optical guard band overhead it is beneficial to switch fixed size bursts of data cells on a time slot basis. The high capacity of the optical matrix supports multiple optical ports per burst card, and the implementation of multiple queue servers per burst card helps make better use of the multiplicity of ports. Problems associated with arbitrating multiple ports and multiple servers per burst card have been resolved by extending the operation of existing iterative, single server scheduling algorithms. The multiserver arbitration time will be in proportion to the number of servers -- corresponding to the channels of DWDM link -- unless a reconciliation stage is used after each iteration when an arbiter per server is used. The reconciliation stage sets the problem of broken data dependencies between server arbitrations in this case. Further, to address the time limitations for computing the scheduling solution, parallel arbiter implementations have been developed and tested against single arbiter designs. Again, the broken dependencies between iterations of an arbitration are addressed through the use of a grant reconciliation stage. The use of multiple queue servers per burst card also resolves some of the data loss problems related to polarized traffic. Simulations of the multiple server and parallel arbiter implementations have demonstrated their efficiency compared to previous implementations. Compounded to this problem is maintaining high throughput of the switch matrix while observing data transit time limits. This involves balancing two contradictory requirements; switch or line card efficiency and data transit times. To improve efficiency it is desirable to transmit only full packets. However, to prevent loss of data due to timeout it will be necessary to transmit some incomplete

  2. Applications of ultrafast wavefront rotation in highly nonlinear optics

    NASA Astrophysics Data System (ADS)

    Quéré, F.; Vincenti, H.; Borot, A.; Monchocé, S.; Hammond, T. J.; Taec Kim, Kyung; Wheeler, J. A.; Zhang, Chunmei; Ruchon, T.; Auguste, T.; Hergott, J. F.; Villeneuve, D. M.; Corkum, P. B.; Lopez-Martens, R.

    2014-06-01

    This paper provides an overview of ultrafast wavefront rotation of femtosecond laser pulses and its various applications in highly nonlinear optics, focusing on processes that lead to the generation of high-order harmonics and attosecond pulses. In this context, wavefront rotation can be exploited in different ways, to obtain new light sources for time-resolved studies, called ‘attosecond lighthouses’, to perform time-resolved measurements of nonlinear optical processes, using ‘photonic streaking’, or to track changes in the carrier-envelope relative phase of femtosecond laser pulses. The basic principles are explained qualitatively from different points of view, the experimental evidence obtained so far is summarized, and the perspectives opened by these effects are discussed.

  3. Ultra-high-speed optical and electronic distributed devices

    SciTech Connect

    Hietala, V.M.; Plut, T.A.; Kravitz, S.H.; Vawter, G.A.; Wendt, J.R.; Armendariz, M.G.

    1995-08-01

    This report summarizes work on the development of ultra-high-speed semiconductor optical and electronic devices. High-speed operation is achieved by velocity matching the input stimulus to the output signal along the device`s length. Electronic devices such as field-effect transistors (FET`s), should experience significant speed increases by velocity matching the electrical input and output signals along the device. Likewise, optical devices, which are typically large, can obtain significant bandwidths by velocity matching the light being generated, detected or modulated with the electrical signal on the device`s electrodes. The devices discussed in this report utilize truly distributed electrical design based on slow-wave propagation to achieve velocity matching.

  4. Thermal refocusing method for spaceborne high-resolution optical imagers.

    PubMed

    Selımoglu, Ozgur; Ekinci, Mustafa; Karcı, Ozgur

    2016-05-20

    We describe the design of a thermal refocusing method for spaceborne high-resolution imagers where Korsch optical design is usually implemented. The secondary mirror is made of aluminum, a high thermal expansion coefficient material, instead of conventional zero-expansion glass ceramics. In this way, the radius of the curvature can be controlled by means of temperature change of the mirror. Change in the radius of curvature also changes the effective focal length of the camera which is used for compensation of the defocus that occurred in space. We show that the 30 μm despace of the secondary mirror in the optical system can be compensated by an ∼10°C temperature change of the mirror while the image quality is maintained. PMID:27411138

  5. Properties of the long-term optical activity of the prototype polar AM Herculis

    NASA Astrophysics Data System (ADS)

    Šimon, Vojtěch

    2016-08-01

    AM Her displays strong long-term activity with the high and low states. This investigation uses AAVSO optical data for a time-series analysis of the long-term variations. Rapid changes of brightness (e.g. the orbital modulation) were smoothed out to emphasise the activity on super-orbital time-scale. I show that the character of this activity changed considerably on time-scales of years, which is reflected in a large evolution of the complicated histogram of the optical brightness. The high states are not the well-defined, narrow levels of brightness. I also show that AM Her displays transitions between the high and low states with the intermittently existing cycles. The longest uninterrupted series of transitions from the high to low state consists of seven episodes (about six years). The existence of this series can be controlled by the lifetime of the active regions on the donor, which modulates the mass transfer rate. I show that the episodes of the high and low states accumulate in clusters, which produces an additional cycle after smoothing by the moving averages. The cycles of activity of the donor can explain this modulation. A single isolated short episode of the low state does not imply a break of this cycle. I also argue that the specific properties of star spots and their migration caused by the differential rotation of the donor would be needed to explain the complex activity of AM Her.

  6. High speed infrared optical wireless for home access networks

    NASA Astrophysics Data System (ADS)

    O'Brien, Dominic C.

    2013-12-01

    The availability of high-bandwidth internet connections to home gateways will place increasing demands on the home access network that provides connections to computers and other devices. In this paper the use of infrared optical wireless to provide connections to user appliances and terminals is discussed. The design and implementation of two demonstration systems operating at hundreds of Mbit/s and above are detailed. Future challenges are also discussed.

  7. High field optical nonlinearity and the Kramers-Kronig relations.

    PubMed

    Wahlstrand, J K; Cheng, Y-H; Milchberg, H M

    2012-09-14

    The nonlinear optical response to high fields is absolutely measured for the noble gas atoms He, Ne, Ar, Kr, and Xe. We find that the response is quadratic in the laser field magnitude up to the ionization threshold of each gas. Its size and quadratic dependence are well predicted by a Kramers-Kronig analysis employing known ionization probabilities, and the results are consistent with calculations using the time-dependent Schrödinger equation.

  8. Progress Toward Demonstrating a High Performance Optical Tape Recording Technology

    NASA Technical Reports Server (NTRS)

    Oakley, W. S.

    1996-01-01

    This paper discusses the technology developments achieved during the first year of a program to develop a high performance digital optical tape recording device using a solid state, diode pumped, frequency doubled green laser source. The goal is to demonstrate, within two years, useful read/write data transfer rates to at least 100 megabytes per second and a user capacity of up to one terabyte per cartridge implemented in a system using a '3480' style mono-reel tape cartridge.

  9. Optical strain measuring techniques for high temperature tensile testing

    NASA Technical Reports Server (NTRS)

    Gyekenyesi, John Z.; Hemann, John H.

    1987-01-01

    A number of optical techniques used for the analysis of in-plane displacements or strains are reviewed. The application would be for the high temperature, approximately 1430 C (2600 F), tensile testing of ceramic composites in an oxidizing atmosphere. General descriptions of the various techniques and specifics such as gauge lengths and sensitivities are noted. Also, possible problems with the use of each method in the given application are discussed.

  10. Highly birefringent low-mode-asymmetry microstructured optical fibres

    SciTech Connect

    Denisov, A N; Levchenko, A E; Semenov, S L; Dianov, Evgenii M

    2011-03-31

    A novel birefringent microstructured fibre (BMF) design is proposed, and its birefringence and dispersion characteristics are analysed using the finite element method. The results indicate that the proposed BMF design ensures high birefringence ({approx}5x10{sup -3}) at a low mode asymmetry. At a certain core ellipticity, the BMF configurations considered may have equal mode field sizes along two orthogonal axes. (fibre optics)

  11. High gain preamplifier based on optical parametric amplification

    DOEpatents

    Jovanovic, Igor; Bonner, Randal A.

    2004-08-10

    A high-gain preamplifier based on optical parametric amplification. A first nonlinear crystal is operatively connected to a second nonlinear crystal. A first beam relay telescope is operatively connected to a second beam relay telescope, to the first nonlinear crystal, and to the second nonlinear crystal. A first harmonic beamsplitter is operatively connected to a second harmonic beamsplitter, to the first nonlinear crystal, to the second nonlinear crystal, to the first beam relay telescope, and to the second beam relay telescope.

  12. High-performance multi-megahertz optical coherence tomography based on amplified optical time-stretch

    PubMed Central

    Xu, Jingjiang; Wei, Xiaoming; Yu, Luoqin; Zhang, Chi; Xu, Jianbing; Wong, K. K. Y.; Tsia, Kevin K.

    2015-01-01

    As the key prerequisite of high-speed volumetric structural and functional tissue imaging in real-time, scaling the A-scan rate beyond MHz has been one of the major pursuits in the development of optical coherence tomography (OCT). Along with a handful of techniques enabling multi-MHz, amplified optical time-stretch OCT (AOT-OCT) has recently been demonstrated as a viable alternative for ultrafast swept-source OCT well above MHz without the need for the mechanical wavelength-tuning mechanism. In this paper, we report a new generation of AOT-OCT demonstrating superior performance to its older generation and all other time-stretch-based OCT modalities in terms of shot-to-shot stability, sensitivity (~90dB), roll-off performance (>4 mm/dB) and A-scan rate (11.5 MHz). Such performance is mainly attributed to the combined contribution from the stable operation of the broadband and compact mode-locked fiber laser as well as the optical amplification in-line with the time-stretch process. The system allows us, for the first time, to deliver volumetric time-stretch-based OCT of biological tissues with the single-shot A-scan rate beyond 10 MHz. Comparing with the existing high-speed OCT systems, the inertia-free AOT-OCT shows promises to realize high-performance 3D OCT imaging at video rate. PMID:25909017

  13. Active x-ray optics for the next generation of x-ray telescopes

    NASA Astrophysics Data System (ADS)

    Atkins, Carolyn; Wang, Hongchang; Doel, Peter; Brooks, David; Thompson, Samantha; Feldman, Charlotte; Willingale, Richard; Button, Tim; Rodriguez Sanmartin, Daniel; Zhang, Dou; James, Ady; Theobald, Craig; Willis, Graham; Smith, Andrew D.

    2009-05-01

    The immediate future for X-ray astronomy is the need for high sensitivity, requiring large apertures and collecting areas, the newly combined NASA, ESA and JAXA mission IXO (International X-ray Observatory) is specifically designed to meet this need. However, looking beyond the next decade, there have been calls for an X-ray space telescope that can not only achieve this high sensitivity, but could also boast an angular resolution of 0.1 arc-seconds, a factor of five improvement on the Chandra X-ray Observatory. NASA's proposed Generation-X mission is designed to meet this demand; it has been suggested that the X-ray optics must be active in nature in order to achieve this desired resolution. The Smart X-ray Optics (SXO) project is a UK based consortium looking at the application of active/adaptive optics to both large and small scale devices, intended for astronomical and medical purposes respectively. With Generation-X in mind, an active elliptical prototype has been designed by the SXO consortium to perform point-to-point X-ray focussing, while simultaneously manipulating its optical surface to improve its initial resolution. Following the completion of the large scale SXO prototype, presented is an overview of the production and operation of the prototype, with emphasis on the X-ray environment and preliminary results.

  14. Lipase-catalyzed preparation of optically active 1'-acetoxychavicol acetates and their structure-activity relationships in apoptotic activity against human leukemia HL-60 cells.

    PubMed

    Azuma, Hideki; Miyasaka, Keita; Yokotani, Tsuyoshi; Tachibana, Taro; Kojima-Yuasa, Akiko; Matsui-Yuasa, Isao; Ogino, Kenji

    2006-03-15

    Structure-activity relationships of 1'-acetoxychavicol acetate (ACA) for apoptotic activity against human leukemia HL-60 cells were investigated using optically active ACA and various racemic ACA analogues. Natural-type (or with different acyl group) ACA showed a high apoptotic activity, but the ortho or meta isomers, 4-deacetoxy analogue, and the 2'-3' dehydrogenated derivative had no effect, or a weak activity. Optically active (R)- and (S)-ACA were prepared by a lipase-catalyzed esterification. Using a mixture of vinyl acetate-tetrahydrofuran (1:1 v/v) as a solvent at refluxing temperature, optically pure (R)- and (S)-ACA were obtained (99.7% ee and 99.1% ee, respectively). The apoptosis-inducing effects of both enantiomers were compared by means of an MTT assay and the detection of typical apoptotic phenomena (DNA fragmentation, caspase-3 activation, and PARP cleavage) and these two activities were almost equal. These results indicate that the essential moieties of ACA for apoptotic activity against HL-60 cells are both the presence of a 4-acetoxyl group and an unsaturated double bond between C-2' and C-3', and that the configuration at the 1'-position is unrelated to activity.

  15. Hybrid silicon-electro-optic-polymer integrated high-performance optical modulator

    NASA Astrophysics Data System (ADS)

    Zhang, Xingyu; Hosseini, Amir; Luo, Jingdong; Jen, Alex K.-Y.; Chen, Ray T.

    2014-03-01

    We design and demonstrate a compact and low-power band-engineered electro-optic (EO) polymer refilled silicon slot photonic crystal waveguide (PCW) modulator. The EO polymer is engineered for large EO activity and nearinfrared transparency. A PCW step coupler is used for optimum coupling to the slow-light mode of the bandengineered PCW. The half-wave switching-voltage is measured to be Vπ=0.97+/-0.02V over optical spectrum range of 8nm, corresponding to the effective in-device r33 of 1190pm/V and Vπ×L of 0.291+/-0.006V×mm in a push-pull configuration. Excluding the slow-light effect, we estimate the EO polymer is poled with an efficiency of 89pm/V in the slot.

  16. High-order parabolic beam approximation for aero-optics

    SciTech Connect

    White, Michael D.

    2010-08-01

    The parabolic beam equations are solved using high-order compact differences for the Laplacians and Runge-Kutta integration along the beam path. The solution method is verified by comparison to analytical solutions for apertured beams and both constant and complex index of refraction. An adaptive 4th-order Runge-Kutta using an embedded 2nd-order method is presented that has demonstrated itself to be very robust. For apertured beams, the results show that the method fails to capture near aperture effects due to a violation of the paraxial approximation in that region. Initial results indicate that the problem appears to be correctable by successive approximations. A preliminary assessment of the effect of turbulent scales is undertaken using high-order Lagrangian interpolation. The results show that while high fidelity methods are necessary to accurately capture the large scale flow structure, the method may not require the same level of fidelity in sampling the density for the index of refraction. The solution is used to calculate a phase difference that is directly compared with that commonly calculated via the optical path difference. Propagation through a supersonic boundary layer shows that for longer wavelengths, the traditional method to calculate the optical path is less accurate than for shorter wavelengths. While unlikely to supplant more traditional methods for most aero-optics applications, the current method can be used to give a quantitative assessment of the other methods as well as being amenable to the addition of more physics.

  17. SMART composite high pressure vessels with integrated optical fiber sensors

    NASA Astrophysics Data System (ADS)

    Blazejewski, Wojciech; Czulak, Andrzej; Gasior, Pawel; Kaleta, Jerzy; Mech, Rafal

    2010-04-01

    In this paper application of integrated Optical Fiber Sensors for strain state monitoring of composite high pressure vessels is presented. The composite tanks find broad application in areas such as: automotive industry, aeronautics, rescue services, etc. In automotive application they are mainly used for gaseous fuels storage (like CNG or compressed Hydrogen). In comparison with standard steel vessels, composite ones have many advantages (i.e. high mechanical strength, significant weight reduction, etc). In the present work a novel technique of vessel manufacturing, according to this construction, was applied. It is called braiding technique, and can be used as an alternative to the winding method. During braiding process, between GFRC layers, two types of optical fiber sensors were installed: point sensors in the form of FBGs as well as interferometric sensors with long measuring arms (SOFO®). Integrated optical fiber sensors create the nervous system of the pressure vessel and are used for its structural health monitoring. OFS register deformation areas and detect construction damages in their early stage (ensure a high safety level for users). Applied sensor system also ensured a possibility of strain state monitoring even during the vessel manufacturing process. However the main application of OFS based monitoring system is to detect defects in the composite structure. An idea of such a SMART vessel with integrated sensor system as well as an algorithm of defect detection was presented.

  18. Are passive red spirals truly passive?. The current star formation activity of optically red disc galaxies

    NASA Astrophysics Data System (ADS)

    Cortese, L.

    2012-07-01

    We used GALEX ultraviolet and WISE 22 μm observations to investigate the current star formation activity of the optically red spirals recently identified as part of the Galaxy Zoo project. These galaxies were accurately selected from the Sloan Digital Sky Survey as pure discs with low or no current star formation activity, representing one of the best optically selected samples of candidate passive spirals. However, we show that these galaxies are not only still forming stars at a significant rate (≳1 M⊙ yr-1) but, more importantly, their star formation activity is not different from that of normal star-forming discs of the same stellar mass (M∗ ≳ 1010.2 M⊙). Indeed, these systems lie on the UV-optical blue sequence, even without any corrections for internal dust attenuation, and they follow the same specific star formation rate vs. stellar mass relation of star-forming galaxies. Our findings clearly show that at high stellar masses, optical colours do not allow to distinguish between actively star-forming and truly quiescent systems.

  19. Active Star Configured Fiber Optic CSMA/CD LANs

    NASA Astrophysics Data System (ADS)

    Truman, Alan K.; Smith, Robert W.; Schmidt, Ronald V.

    1987-01-01

    The widespread use of the IEEE 802.3 CSMA/CD (Ethernet) Local Area Network (LAN) has created demand for a fiber optic physical layer implementation to address security issues, hostile electromagnetic environments, modern structured wiring requirements and distance limitations of coaxial based implementations. Active Star CSMA/CD LANs will be described in this paper which consist of a central wiring Concentrator which supports point to point fiber links to Media Access Units (Transceivers) located at the Host computers. The fiber optic Active Star configured CSMA/CD LAN implementation provides a robust network which meets all the requirements imposed on an Ethernet Physical Layer. Collision detection is reliably performed in the electrical domain of the Concentrator. Network requirements included guaranteed collision detection, network reliability and easy addition and rearrangement of host connections. In addition, the Active Star implementation can provide an increased network diameter to 4.2 km and can support the four basic multimode fiber types, simultaneously, with substantial system margins.

  20. Application of Optical Biosensors in Small-Molecule Screening Activities

    PubMed Central

    Geschwindner, Stefan; Carlsson, Johan F.; Knecht, Wolfgang

    2012-01-01

    The last two decades have seen remarkable progress and improvements in optical biosensor systems such that those are currently seen as an important and value-adding component of modern drug screening activities. In particular the introduction of microplate-based biosensor systems holds the promise to match the required throughput without compromising on data quality thus representing a sought-after complement to traditional fluidic systems. This article aims to highlight the application of the two most prominent optical biosensor technologies, namely surface plasmon resonance (SPR) and optical waveguide grating (OWG), in small-molecule screening and will present, review and discuss the advantages and disadvantages of different assay formats on these platforms. A particular focus will be on the specific advantages of the inhibition in solution assay (ISA) format in contrast to traditional direct binding assays (DBA). Furthermore we will discuss different application areas for both fluidic as well as plate-based biosensor systems by considering the individual strength of the platforms. PMID:22666031

  1. Integration of magneto-optical active bismuth iron garnet on nongarnet substrates

    NASA Astrophysics Data System (ADS)

    Körner, Timo; Heinrich, Andreas; Weckerle, Martin; Roocks, Patrick; Stritzker, Bernd

    2008-04-01

    For optical communication, high quality magneto-optical active iron garnet films such as Y3Fe5O12 are important ceramic systems with extensive applications, e.g., as optical isolators [H. Dötsch et al., J. Opt. Soc. Am. B 22, 240 (2005)], optical modulators, etc. Thereby, garnets stand out due to their high Faraday rotation and low optical losses in the near infrared. Currently, it is desirable to integrate such macroscopic optical components on a single chip (Si, SiO2, etc.) to build up optical circuits as in the case of microelectronics (integrated optics) or the use for magneto-optical imaging. Up to now, Bi3Fe5O12 shows the highest Faraday rotation over 20°/μm. Unfortunately, Bi3Fe5O12 forms in a nonthermodynamical way. Thus, it can only be grown on garnet substrates which prevent it from direct deposition on substrates such as Si or SiO2. In our present work, we studied the integration of Bi3Fe5O12 on different SiO2 substrates using the pulsed laser deposition method. Therefore, we deposited an Y3Fe5O12 buffer first which was optimized in a postannealing step above 900°C in order to form a polycrystalline garnet phase, which is needed for further Bi3Fe5O12 growth. We measured the Faraday rotation of the double layered films and intensely studied them with x-ray diffraction, Rutherford backscattering spectroscopy, environmental scanning electron microscopy, and high-resolution transmission electron microscopy. The attained Faraday rotation can be compared with epitaxial Bi3Fe5O12 films grown on Gd3Ga5O12 substrates or even overcome them due to interference effects in the double layer. So they are highly attractive for magneto-optical imaging. For the determination of the film thicknesses which is usually done by Rutherford backscattering or profilometry, we used another approach. We measured the transmission spectra of the stack which we also derived from a theoretical model that uses a transfer matrix formalism. The thickness of the multilayer can be

  2. Zeno inhibition of polarization rotation in an optically active medium

    NASA Astrophysics Data System (ADS)

    Gonzalo, Isabel; Porras, Miguel A.; Luis, Alfredo

    2015-07-01

    We describe an experiment in which the rotation of the polarization of light propagating in an optically active water solution of D-fructose tends to be inhibited by frequent monitoring whether the polarization remains unchanged. This is an example of the Zeno effect that has remarkable pedagogical interest because of its conceptual simplicity, easy implementation, low cost, and because the same the Zeno effect holds at classical and quantum levels. An added value is the demonstration of the Zeno effect beyond typical idealized assumptions in a practical setting with real polarizers.

  3. Calculation of optical second-harmonic susceptibilities and optical activity for crystals

    SciTech Connect

    Levine, Z.H.

    1994-12-31

    A new generation of nearly first-principles calculations predicts both the linear and second-harmonic susceptibilities for a variety of insulating crystals, including GaAs, GaP, AlAs, AlP, Se, {alpha}-quartz, and c-urea. The results are typically in agreement with experimental measurements. The calculations have been extended to optical activity, with somewhat less success to date. The theory, based on a simple self-energy correction to the local density approximation, and results are reviewed herein.

  4. Automated packaging platform for low-cost high-performance optical components manufacturing

    NASA Astrophysics Data System (ADS)

    Ku, Robert T.

    2004-05-01

    Delivering high performance integrated optical components at low cost is critical to the continuing recovery and growth of the optical communications industry. In today's market, network equipment vendors need to provide their customers with new solutions that reduce operating expenses and enable new revenue generating IP services. They must depend on the availability of highly integrated optical modules exhibiting high performance, small package size, low power consumption, and most importantly, low cost. The cost of typical optical system hardware is dominated by linecards that are in turn cost-dominated by transmitters and receivers or transceivers and transponders. Cost effective packaging of optical components in these small size modules is becoming the biggest challenge to be addressed. For many traditional component suppliers in our industry, the combination of small size, high performance, and low cost appears to be in conflict and not feasible with conventional product design concepts and labor intensive manual assembly and test. With the advent of photonic integration, there are a variety of materials, optics, substrates, active/passive devices, and mechanical/RF piece parts to manage in manufacturing to achieve high performance at low cost. The use of automation has been demonstrated to surpass manual operation in cost (even with very low labor cost) as well as product uniformity and quality. In this paper, we will discuss the value of using an automated packaging platform.for the assembly and test of high performance active components, such as 2.5Gb/s and 10 Gb/s sources and receivers. Low cost, high performance manufacturing can best be achieved by leveraging a flexible packaging platform to address a multitude of laser and detector devices, integration of electronics and handle various package bodies and fiber configurations. This paper describes the operation and results of working robotic assemblers in the manufacture of a Laser Optical Subassembly

  5. Activation of cell signaling via optical manipulation of gold-coated liposomes encapsulating signaling molecules

    NASA Astrophysics Data System (ADS)

    Orsinger, Gabriel V.; Leung, Sarah J.; Romanowski, Marek

    2013-02-01

    Many diseases involve changes in cell signaling cascades, as seen commonly in drug resistant cancers. To better understand these intricate signaling events in diseased cells and tissues, experimental methods of probing cellular communication at a single to multi-cell level are required. We recently introduced a general platform for activation of selected signaling pathways by optically controlled delivery and release of water soluble factors using gold-coated liposomes. In the example presented here, we encapsulated inositol trisphosphate (IP3), a ubiquitous intracellular secondary messenger involved in GPCR and Akt signaling cascades, within 100 nm gold-coated liposomes. The high polarizability of the liposome's unique gold pseudo-shell allows stable optical trapping for subcellular manipulation in the presence of cells. We take this optical manipulation further by optically injecting IP3-containing liposomes into the cytosol of a single cell to initiate localized cell signaling. Upon optical injection of liposomal IP3 into a single ovarian carcinoma cell, we observed localized activation as reported by changes in Indo-1 fluorescence intensity. With established gap junctions between the injected cell and neighboring cells, we monitored propagation of this signaling to and through nearby cells.

  6. Precision glass molding of high-resolution diffractive optical elements

    NASA Astrophysics Data System (ADS)

    Prater, Karin; Dukwen, Julia; Scharf, Toralf; Herzig, Hans P.; Plöger, Sven; Hermerschmidt, Andreas

    2016-04-01

    The demand of high resolution diffractive optical elements (DOE) is growing. Smaller critical dimensions allow higher deflection angles and can fulfill more demanding requirements, which can only be met by using electron-beam lithography. Replication techniques are more economical, since the high cost of the master can be distributed among a larger number of replicas. The lack of a suitable mold material for precision glass molding has so far prevented an industrial use. Glassy Carbon (GC) offers a high mechanical strength and high thermal strength. No anti-adhesion coatings are required in molding processes. This is clearly an advantage for high resolution, high aspect ratio microstructures, where a coating with a thickness between 10 nm and 200 nm would cause a noticeable rounding of the features. Electron-beam lithography was used to fabricate GC molds with highest precision and feature sizes from 250 nm to 2 μm. The master stamps were used for precision glass molding of a low Tg glass L-BAL42 from OHARA. The profile of the replicated glass is compared to the mold with the help of SEM images. This allows discussion of the max. aspect-ratio and min. feature size. To characterize optical performances, beamsplitting elements are fabricated and their characteristics were investigated, which are in excellent agreement to theory.

  7. Highly integrated optical microsystem for particle concentration measurement

    NASA Astrophysics Data System (ADS)

    Hofmann, Meike; Ma, Xuan; Schneider, Jan; Sinzinger, Stefan

    2010-05-01

    We present our research on integrated optical Talbot interferometers for particle mass concentration measurements. For optimum integration of highly sensitive optical measurement systems we apply a planar emitter-receiver-unit with a vertical cavity surface emitting laser (VCSEL) at 850 nm as light source. The optical system is integrated into a planar transparent PMMA (polymethylmethacrylate) substrate. We suggest a planar integrated free-space optical system for monitoring the particle mass concentration of polydisperse suspensions. Thorough simulations of the optical sensor show that for the required regime of particle concentration and particle size distribution (PSD) turbidity measurements where the attenuation of a light beam is evaluated for example at different wavelengths do not provide the required measurement precision. We therefore propose a system where the probe beam even though sent through the system is blocked before reaching the detector by an interferometric setup. The stray light originating from the particles is exploited for the measurement. For our application we focus on particles with sizes in the range 1 - 120 μm and particle mass concentrations in the range of 1-10 mg/L. In this case significant strength of the scattering signal only appears in small angles relative to the incident probe beam (forward scattering). The probe beam and the stray light thus overlap to a large extent. Our sensor concept is based on a monolithically integrated Talbot interferometer. Two properly aligned diffraction gratings are used to remove the primary beam. We use a stripe detector as second grating. The stray light causes perturbations within the formation of the self image of the grating. These perturbations are visualized as speckles on a detector and exploited for particle concentration measurements. The potential of the sensor concept is presented on the example of a modular Talbot interferometer using a HeNe laser at 633 nm to measure particle mass

  8. Active mode-locked lasers and other photonic devices using electro-optic whispering gallery mode resonators

    NASA Technical Reports Server (NTRS)

    Matsko, Andrey B. (Inventor); Ilchenko, Vladimir (Inventor); Savchenkov, Anatoliy (Inventor); Maleki, Lutfollah (Inventor)

    2006-01-01

    Techniques and devices using whispering gallery mode (WGM) optical resonators, where the optical materials of the WGM resonators exhibit an electro-optical effect to perform optical modulation. Examples of actively mode-locked lasers and other devices are described.

  9. Fast calibration of high-order adaptive optics systems.

    PubMed

    Kasper, Markus; Fedrigo, Enrico; Looze, Douglas P; Bonnet, Henri; Ivanescu, Liviu; Oberti, Sylvain

    2004-06-01

    We present a new method of calibrating adaptive optics systems that greatly reduces the required calibration time or, equivalently, improves the signal-to-noise ratio. The method uses an optimized actuation scheme with Hadamard patterns and does not scale with the number of actuators for a given noise level in the wavefront sensor channels. It is therefore highly desirable for high-order systems and/or adaptive secondary systems on a telescope without a Gregorian focal plane. In the latter case, the measurement noise is increased by the effects of the turbulent atmosphere when one is calibrating on a natural guide star. PMID:15191182

  10. Fast calibration of high-order adaptive optics systems.

    PubMed

    Kasper, Markus; Fedrigo, Enrico; Looze, Douglas P; Bonnet, Henri; Ivanescu, Liviu; Oberti, Sylvain

    2004-06-01

    We present a new method of calibrating adaptive optics systems that greatly reduces the required calibration time or, equivalently, improves the signal-to-noise ratio. The method uses an optimized actuation scheme with Hadamard patterns and does not scale with the number of actuators for a given noise level in the wavefront sensor channels. It is therefore highly desirable for high-order systems and/or adaptive secondary systems on a telescope without a Gregorian focal plane. In the latter case, the measurement noise is increased by the effects of the turbulent atmosphere when one is calibrating on a natural guide star.

  11. Highly Non-Linear Optical (NLO) organic crystals

    NASA Technical Reports Server (NTRS)

    Harris, J. Milton

    1987-01-01

    This research project involves the synthesis and characterization of organic materials having powerful nonlinear optical (NLO) properties and the growth of highly ordered crystals and monomolecular films of these materials. Research in four areas is discussed: theoretical design of new materials, characterization of NLO materials, synthesis of new materials and development of coupling procedures for forming layered films, and improvement of the techniques for vapor phase and solution phase growth of high quality organic crystals. Knowledge gained from these experiments will form the basis for experiments in the growth of these crystals.

  12. Applications of nonimaging optics for very high solar concentrations

    SciTech Connect

    O`Gallagher, J.; Winston, R.

    1997-12-31

    Using the principles and techniques of nonimaging optics, solar concentrations that approach the theoretical maximum can be achieved. This has applications in solar energy collection wherever concentration is desired. In this paper, we survey recent progress in attaining and using high and ultrahigh solar fluxes. We review a number of potential applications for highly concentrated solar energy and the current status of the associated technology. By making possible new and unique applications for intense solar flux, these techniques have opened a whole new frontier for research and development of potentially economic uses of solar energy.

  13. High speed optical phased array using high contrast grating all-pass filters.

    PubMed

    Yang, Weijian; Sun, Tianbo; Rao, Yi; Megens, Mischa; Chan, Trevor; Yoo, Byung-Wook; Horsley, David A; Wu, Ming C; Chang-Hasnain, Connie J

    2014-08-25

    We report a high speed 8x8 optical phased array using tunable 1550 nm all-pass filters with ultrathin high contrast gratings (HCGs) as the microelectromechanical-actuated top reflectors. The all-pass filter design enables a highly efficient phase tuning (1.7 π) with a small actuation voltage (10 V) and actuation displacement of the HCG (50 nm). The microelectromechanical HCG structure facilitates a high phase tuning speed >0.5 MHz. Beam steering is experimentally demonstrated with the optical phased array.

  14. Fiber optic illumination by laser activated remote phosphor

    NASA Astrophysics Data System (ADS)

    Hartwig, Ulrich

    2012-10-01

    For some fiber optic applications, like high-end endoscopy, light sources with high luminance are necessary. Currently, short arc discharge lamps are being used. However, more and more LED solutions are trying to compete, but they can not yet reach the performance obtainable by 300 W Xenon short arc discharge lamps. To make this field of application accessible for solid state light sources, a new approach is necessary. Diode lasers have rapidly advanced in the past years. This is particularly true for multimode laser diodes emitting at around 445 nm wavelength. Single diodes emitting more than 1 W of optical power are already available. These laser sources exhibit extremely high radiance, thus they can be focused onto very small areas. Phosphors placed near the focus can result in high luminance sources. On the basis of this idea, a device has been developed to match the performance of a state of the art 300 W Xenon lamp system. An array of laser diodes is used to illuminate a phosphor plate which converts the blue pump light into yellow light. The converted light is collected and adapted to the application by a tapered TIR rod. To achieve a color point on the Planckian locus at 6000 K, the light of an LED emitting at around 460 nm is superimposed to the converted light.

  15. High doses of cobalt induce optic and auditory neuropathy.

    PubMed

    Apostoli, Pietro; Catalani, Simona; Zaghini, Anna; Mariotti, Andrea; Poliani, Pietro Luigi; Vielmi, Valentina; Semeraro, Francesco; Duse, Sarah; Porzionato, Andrea; Macchi, Veronica; Padovani, Alessandro; Rizzetti, Maria Cristina; De Caro, Raffaele

    2013-09-01

    The adverse biological effects of continuous exposure to cobalt and chromium have been well defined. In the past, this toxicity was largely an industrial issue concerning workers exposed in occupational setting. Nevertheless, recent reports have described a specific toxicity mediated by the high levels of cobalt and chromium released by metallic prostheses, particularly in patients who had received hip implants. Clinical symptoms, including blindness, deafness and peripheral neuropathy, suggest a specific neurotropism. However, little is known about the neuropathological basis of this process, and experimental evidence is still lacking. We have investigated this issue in an experimental setting using New Zealand White rabbits treated with repeated intravenous injections of cobalt and chromium, alone or in combination. No evident clinical or pathological alterations were associated after chromium administration alone, despite its high levels in blood and tissue while cobalt-chromium and cobalt-treated rabbits showed clinical signs indicative of auditory and optic system toxicity. On histopathological examination, the animals showed severe retinal and cochlear ganglion cell depletion along with optic nerve damage and loss of sensory cochlear hair cells. Interestingly, the severity of the alterations was related to dosages and time of exposure. These data confirmed our previous observation of severe auditory and optic nerve toxicity in patients exposed to an abnormal release of cobalt and chromium from damaged hip prostheses. Moreover, we have identified the major element mediating neurotoxicity to be cobalt, although the molecular mechanisms mediating this toxicity still have to be defined.

  16. High power compatible internally sensed optical phased array.

    PubMed

    Roberts, Lyle E; Ward, Robert L; Francis, Samuel P; Sibley, Paul G; Fleddermann, Roland; Sutton, Andrew J; Smith, Craig; McClelland, David E; Shaddock, Daniel A

    2016-06-13

    The technical embodiment of the Huygens-Fresnel principle, an optical phased array (OPA) is an arrangement of optical emitters with relative phases controlled to create a desired beam profile after propagation. One important application of an OPA is coherent beam combining (CBC), which can be used to create beams of higher power than is possible with a single laser source, especially for narrow linewidth sources. Here we present an all-fiber architecture that stabilizes the relative output phase by inferring the relative path length differences between lasers using the small fraction of light that is back-reflected into the fiber at the OPA's glass-air interface, without the need for any external sampling optics. This architecture is compatible with high power continuous wave laser sources (e.g., fiber amplifiers) up to 100 W per channel. The high-power compatible internally sensed OPA was implemented experimentally using commercial 15 W fiber amplifiers, demonstrating an output RMS phase stability of λ/194, and the ability to steer the beam at up to 10 kHz. PMID:27410363

  17. High power compatible internally sensed optical phased array.

    PubMed

    Roberts, Lyle E; Ward, Robert L; Francis, Samuel P; Sibley, Paul G; Fleddermann, Roland; Sutton, Andrew J; Smith, Craig; McClelland, David E; Shaddock, Daniel A

    2016-06-13

    The technical embodiment of the Huygens-Fresnel principle, an optical phased array (OPA) is an arrangement of optical emitters with relative phases controlled to create a desired beam profile after propagation. One important application of an OPA is coherent beam combining (CBC), which can be used to create beams of higher power than is possible with a single laser source, especially for narrow linewidth sources. Here we present an all-fiber architecture that stabilizes the relative output phase by inferring the relative path length differences between lasers using the small fraction of light that is back-reflected into the fiber at the OPA's glass-air interface, without the need for any external sampling optics. This architecture is compatible with high power continuous wave laser sources (e.g., fiber amplifiers) up to 100 W per channel. The high-power compatible internally sensed OPA was implemented experimentally using commercial 15 W fiber amplifiers, demonstrating an output RMS phase stability of λ/194, and the ability to steer the beam at up to 10 kHz.

  18. High-power diode lasers for optical communications applications

    NASA Technical Reports Server (NTRS)

    Carlin, D. B.; Goldstein, B.; Channin, D. J.

    1985-01-01

    High-power, single-mode, double-heterojunction AlGaAs diode lasers are being developed to meet source requirements for both fiber optic local area network and free space communications systems. An individual device, based on the channeled-substrate-planar (CSP) structure, has yielded single spatial and longitudinal mode outputs of up to 90 mW CW, and has maintained a single spatial mode to 150 mW CW. Phase-locked arrays of closely spaced index-guided lasers have been designed and fabricated with the aim of multiplying the outputs of the individual devices to even higher power levels in a stable, single-lobe, anastigmatic beam. The optical modes of the lasers in such arrays can couple together in such a way that they appear to be emanating from a single source, and can therefore be efficiently coupled into optical communications systems. This paper will review the state of high-power laser technology and discuss the communication system implications of these devices.

  19. Highly sensitive and reconfigurable fiber optic current sensor by optical recirculating in a fiber loop.

    PubMed

    Du, Jiangbing; Tao, Yemeng; Liu, Yinping; Ma, Lin; Zhang, Wenjia; He, Zuyuan

    2016-08-01

    An advanced fiber optic current sensor (FOCS) is proposed based on recirculating fiber loop architecture for significantly enhancing the current sensitivity. The recirculating loop is constructed by a 2X2 optical switch and the standard single mode fiber (SSMF) is used as the sensing head. The proposed FOCS is coupler-free with low insertion loss which results in a significantly improved current sensitivity. We experimentally obtained a sensitivity of 11.5 degrees/A for 1-Km SSMF FOCS and a sensitivity of 21.2 degrees/A for 500-m SSMF FOCS, both of which have been enhanced by more than ten times. The flexible switch control of recirculating can support the FOCS to work for different current scenarios with the same system and thus reconfigurable operation of the FOCS has been achieved. The significantly enhanced high sensitivity with reconfigurable operation capability makes the proposed FOCS a promising method for practical applications. PMID:27505765

  20. High-order optical processes in intense laser field: Towards nonperturbative nonlinear optics

    NASA Astrophysics Data System (ADS)

    Strelkov, V. V.

    2016-05-01

    We develop an approach describing nonlinear-optical processes in the strong-field domain characterized by the nonperturbative field-with-matter interaction. The polarization of an isolated atom in the external field calculated via the numerical solution of the time-dependent Schrödinger equation agrees with our analytical findings. For the practically important case of one strong laser field and several weaker fields, we derive and analytically solve propagation equations describing high-order (HO) wave mixing, HO parametric amplification, and HO stimulated scattering. These processes provide a way of efficient coherent xuv generation. Some properties of HO processes are new in nonlinear optics: essentially complex values of the coefficients in the propagation equations, the superexponential (hyperbolic) growing solutions, etc. Finally, we suggest conditions for the practical realization of these processes and discuss published numerical and experimental results where such processes could have been observed.

  1. High Activity States of Blazars 1055+018 and 0954+658

    NASA Astrophysics Data System (ADS)

    Jorstad, Svetlana

    2015-02-01

    The BLLac object 1055+018 shows a high activity at optical wavelengths. Our observations at the Perkins telescope (Flagstaff, AZ) on February 17/18, 2015 show that the source is ~ 2mag (R~14.7) brighter and highly polarized (P~24%) than it was during our previous optical observations in 2014 June (R~17.0 and P~5%).

  2. Functional imaging of glucose-evoked rat islet activities using transient intrinsic optical signals

    NASA Astrophysics Data System (ADS)

    Yao, Xin-Cheng; Cui, Wan-Xing; Li, Yi-Chao; Zhang, Wei; Lu, Rong-Wen; Thompson, Anthony; Amthor, Franklin; Wang, Xu-Jing

    2012-05-01

    We demonstrate intrinsic optical signal (IOS) imaging of intact rat islet, which consists of many endocrine cells working together. A near-infrared digital microscope was employed for optical monitoring of islet activities evoked by glucose stimulation. Dynamic NIR images revealed transient IOS responses in the islet activated by low-dose (2.75 mM) and high-dose (5.5 mM) glucose stimuli. Comparative experiments and quantitative analysis indicated that both glucose metabolism and calcium/insulin dynamics might contribute to the observed IOS responses. Further investigation of the IOS imaging technology may provide a high resolution method for ex vivo functional examination of the islet, which is important for advanced study of diabetes associated islet dysfunctions and for improved quality control of donor islets for transplantation.

  3. Optical imaging of neural activity: from neuron to brain

    NASA Astrophysics Data System (ADS)

    Luo, Qingming; Zeng, Shaoqun; Gong, Hui

    2003-12-01

    This paper introduces the optical imaging approaches at three levels in cognitive neuroscience in the Key Laboratory of Biomedical Photonics of Ministry of Education of China. In molecular and cellular level, the advances in microscopy, molecular optical marker, and sample preparations have made possible studies that characterize the form and function of neurons in unprecedented detail. The development of two-photon excitation has enabled fluorescent imaging of small structures in the midst of highly scattering media with little photodamage. The combination of MPE and multi-electrode array provides a powerful approach for neuronal networks imaging. Intrinsic signal imaging (ISI) and laser speckle imaging (LSI) are effective approaches for intrinsic signal imaging at a given cortical site. No alternative imaging technique for the visualization of functional organization in the living brain provides a comparable spatial resolution. It is this level of resolution that reveals where processing is performed - a necessary step for the understanding of the neural code at the population level. Completely noninvasive optical imaging through the intact human skull, such as functional near infrared imaging may provide an imaging tool offering both the spatial and the temporal resolutions required to expand our knowledge of the principles underlying the remarkable performance of the human cerebral cortex.

  4. Wide acceptance angle, high concentration ratio, optical collector

    NASA Technical Reports Server (NTRS)

    Kruer, Mark A. (Inventor)

    1991-01-01

    A cassegrain optical system provides improved collection of off-axis light yet is still characterized by a high concentration ratio. The optical system includes a primary mirror for collecting incoming light and reflecting the light to a secondary mirror which, in turn, reflects the light to a solar cell or other radiation collection device. The primary mirror reflects incoming on-axis light onto an annular section of the secondary mirror and results in the reflection of a substantial amount of incoming off-axis light onto the remainder of the secondary mirror. Thus light which would otherwise be lost to the system will be captured by the collector. Furthermore, the off-axis sections of the secondary mirror may be of a different geometrical shape than the on-axis annular section so as to optimize the amount of off-axis light collected.

  5. Radiation-hard/high-speed data transmission using optical links

    NASA Astrophysics Data System (ADS)

    Gan, K. K.; Abi, B.; Fernando, W.; Kagan, H. P.; Kass, R. D.; Lebbai, M. R. M.; Moore, J. R.; Rizatdinova, F.; Skubic, P. L.; Smith, D. S.

    2009-12-01

    The silicon trackers of the ATLAS experiment at the Large Hadron Collider (LHC) at CERN (Geneva) use optical links for data transmission. An upgrade of the trackers is planned for the Super LHC (SLHC), an upgraded LHC with ten times higher luminosity. We investigate the radiation-hardness of various components for possible application in the data transmission upgrade. We study the radiation-hardness of VCSELs (Vertical-Cavity Surface-Emitting Laser) and GaAs and silicon PINs from various sources using 24 GeV/c protons at CERN. The optical power of VCSEL arrays decreases significantly after the irradiation but can be partially annealed with high drive currents. The responsivities of the PIN diodes also decrease significantly after irradiation, especially for the GaAs devices. We have designed the ASICs for the opto-link applications and find that the degradation with radiation is acceptable.

  6. RadTracker: Optical Imaging of High Energy Radiation Tracks

    SciTech Connect

    Vernon, S P; Lowry, M E; Comaskey, B J; Heebner, J E; Kallman, J S; Richards, J B

    2007-03-02

    This project examined the possibility of extending the recently demonstrated radoptic detection approach to gamma imaging. Model simulations of the light scattering process predicted that expected signal levels were small and likely below the detection limit of large area, room-temperature detectors. A series of experiments using pulsed x-ray excitation, modulated gamma excitation and optical pump-probe methods confirmed those theoretical predictions. At present the technique does not appear to provide a viable approach to volumetric radiation detection; however, in principal, orders of magnitude improvement in the SNR can result by using designer materials to concentrate and localize the radiation-absorption induced charge, simultaneously confining the optical mode to increase 'fill' factor and overlap of the probe beam with the affected regions, and employing high speed gated imaging detectors to measure the scattered signal.

  7. High-performance, scalable optical network-on-chip architectures

    NASA Astrophysics Data System (ADS)

    Tan, Xianfang

    The rapid advance of technology enables a large number of processing cores to be integrated into a single chip which is called a Chip Multiprocessor (CMP) or a Multiprocessor System-on-Chip (MPSoC) design. The on-chip interconnection network, which is the communication infrastructure for these processing cores, plays a central role in a many-core system. With the continuously increasing complexity of many-core systems, traditional metallic wired electronic networks-on-chip (NoC) became a bottleneck because of the unbearable latency in data transmission and extremely high energy consumption on chip. Optical networks-on-chip (ONoC) has been proposed as a promising alternative paradigm for electronic NoC with the benefits of optical signaling communication such as extremely high bandwidth, negligible latency, and low power consumption. This dissertation focus on the design of high-performance and scalable ONoC architectures and the contributions are highlighted as follow: 1. A micro-ring resonator (MRR)-based Generic Wavelength-routed Optical Router (GWOR) is proposed. A method for developing any sized GWOR is introduced. GWOR is a scalable non-blocking ONoC architecture with simple structure, low cost and high power efficiency compared to existing ONoC designs. 2. To expand the bandwidth and improve the fault tolerance of the GWOR, a redundant GWOR architecture is designed by cascading different type of GWORs into one network. 3. The redundant GWOR built with MRR-based comb switches is proposed. Comb switches can expand the bandwidth while keep the topology of GWOR unchanged by replacing the general MRRs with comb switches. 4. A butterfly fat tree (BFT)-based hybrid optoelectronic NoC (HONoC) architecture is developed in which GWORs are used for global communication and electronic routers are used for local communication. The proposed HONoC uses less numbers of electronic routers and links than its counterpart of electronic BFT-based NoC. It takes the advantages of

  8. Design of an experiment to study optically-active centers in diamond nanoparticles

    NASA Astrophysics Data System (ADS)

    Singh, Ankit; Tiwari, Kunal; Sharma, Suresh

    2012-03-01

    The silicon-vacancy (SiV) and nitrogen-vacancy (NV) complexes in diamond nanoparticles (NPs) are optically active centers, which produce single photon events. These centers may be formed when a silicon atom from the silicon substrate often used in CVD growth or nitrogen from impurities in the feed gas ends up next to a vacancy in the diamond lattice. Because of their stability and high quantum efficiency, SiV and NV centers in diamond NPs are attractive for applications in quantum computing, optics, biotechnology, and medicine. We briefly review our recently published results on diamond NPs, describe the design of an experimental system for carrying out in-situ optical spectroscopy and time-correlation measurements, and show preliminary photoluminescence data.

  9. Engineering near-infrared single-photon emitters with optically active spins in ultrapure silicon carbide

    NASA Astrophysics Data System (ADS)

    Fuchs, F.; Stender, B.; Trupke, M.; Simin, D.; Pflaum, J.; Dyakonov, V.; Astakhov, G. V.

    2015-07-01

    Vacancy-related centres in silicon carbide are attracting growing attention because of their appealing optical and spin properties. These atomic-scale defects can be created using electron or neutron irradiation; however, their precise engineering has not been demonstrated yet. Here, silicon vacancies are generated in a nuclear reactor and their density is controlled over eight orders of magnitude within an accuracy down to a single vacancy level. An isolated silicon vacancy serves as a near-infrared photostable single-photon emitter, operating even at room temperature. The vacancy spins can be manipulated using an optically detected magnetic resonance technique, and we determine the transition rates and absorption cross-section, describing the intensity-dependent photophysics of these emitters. The on-demand engineering of optically active spins in technologically friendly materials is a crucial step toward implementation of both maser amplifiers, requiring high-density spin ensembles, and qubits based on single spins.

  10. Engineering near-infrared single-photon emitters with optically active spins in ultrapure silicon carbide.

    PubMed

    Fuchs, F; Stender, B; Trupke, M; Simin, D; Pflaum, J; Dyakonov, V; Astakhov, G V

    2015-07-07

    Vacancy-related centres in silicon carbide are attracting growing attention because of their appealing optical and spin properties. These atomic-scale defects can be created using electron or neutron irradiation; however, their precise engineering has not been demonstrated yet. Here, silicon vacancies are generated in a nuclear reactor and their density is controlled over eight orders of magnitude within an accuracy down to a single vacancy level. An isolated silicon vacancy serves as a near-infrared photostable single-photon emitter, operating even at room temperature. The vacancy spins can be manipulated using an optically detected magnetic resonance technique, and we determine the transition rates and absorption cross-section, describing the intensity-dependent photophysics of these emitters. The on-demand engineering of optically active spins in technologically friendly materials is a crucial step toward implementation of both maser amplifiers, requiring high-density spin ensembles, and qubits based on single spins.

  11. Progress on the development of active micro-structured optical arrays for x-ray optics

    NASA Astrophysics Data System (ADS)

    Rodriguez Sanmartin, Daniel; Zhang, Dou; Button, Tim; Atkins, Carolyn; Doel, Peter; Wang, Hongchang; Brooks, David; Feldman, Charlotte; Willingale, Richard; Michette, Alan; Pfauntsch, Slawka; Sahraei, Shahin; Shand, Matthew; James, Ady; Dunare, Camelia; Stevenson, Tom; Parkes, William; Smith, Andy

    2009-08-01

    The Smart X-Ray Optics (SXO) project comprises a U.K.-based consortium developing active/adaptive micro-structured optical arrays (MOAs). These devices are designed to focus X-rays using grazing incidence reflection through consecutive aligned arrays of microscopic channels etched in silicon. The silicon channels have been produced both by dry and wet etching, the latter providing smoother channel walls. Adaptability is achieved using piezoelectric actuators, which bend the device and therefore change its focal distance. We aim to achieve a 5 cm radius of curvature which can provide a suitable focal length using a tandem pair MOA configuration. Finite Element Analysis (FEA) modelling has been carried out for the optimization of the MOA device design, consider different types of actuators (unimorph, bimorph and active fibre composites), and different Si/piezoelectric absolute and relative thicknesses. Prototype devices have been manufactured using a Viscous Plastic Processing Process for the piezoelectric actuators and dry etched silicon channels, bonded together using a low shrinkage adhesive. Characterisation techniques have been developed in order to evaluate the device performance in terms of the bending of the MOA channels produced by the actuators. This paper evaluates the progress to date on the actuation of the MOAs, comparing FEA modelling with the results obtained for different prototype structures.

  12. Active resonant subwavelength grating devices for high speed spectroscopic sensing

    NASA Astrophysics Data System (ADS)

    Gin, A. V.; Kemme, S. A.; Boye, R. R.; Peters, D. W.; Ihlefeld, J. F.; Briggs, R. D.; Wendt, J. R.; Marshall, L. H.; Carter, T. R.; Samora, S.

    2009-02-01

    In this paper, we describe progress towards a multi-color spectrometer and radiometer based upon an active resonant subwavelength grating (RSG). This active RSG component acts as a tunable high-speed optical filter that allows device miniaturization and ruggedization not realizable using current sensors with conventional bulk optics. Furthermore, the geometrical characteristics of the device allow for inherently high speed operation. Because of the small critical dimensions of the RSG devices, the fabrication of these sensors can prove challenging. However, we utilize the state-of-the-art capabilities at Sandia National Laboratories to realize these subwavelength grating devices. This work also leverages previous work on passive RSG devices with greater than 98% efficiency and ~1nm FWHM. Rigorous coupled wave analysis has been utilized to design RSG devices with PLZT, PMN-PT and BaTiO3 electrooptic thin films on sapphire substrates. The simulated interdigitated electrode configuration achieves field strengths around 3×107 V/m. This translates to an increase in the refractive index of 0.05 with a 40V bias potential resulting in a 90% contrast of the modulated optical signal. We have fabricated several active RSG devices on selected electro-optic materials and we discuss the latest experimental results on these devices with variable electrostatic bias and a tunable wavelength source around 1.5μm. Finally, we present the proposed data acquisition hardware and system integration plans.

  13. Cross-sectional imaging of functional activation in the rat somatosensory cortex with optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Aguirre, A. D.; Chen, Y.; Ruvinskaya, L.; Devor, A.; Boas, D. A.; Fujimoto, J. G.

    2005-08-01

    Simultaneous optical coherence tomography (OCT) and video microscopy were performed on the rat somatosensory cortex through a thinned skull during forepaw stimulation. Fractional change measurements in OCT images reveal a functional signal timecourse similar to well understood hemodynamic signal timecourses measured with video microscopy. The precise etiology of the observed OCT functional signal is still under investigation, but these results suggest that OCT can provide high-resolution cross-sectional images of functional neuro-vascular activation.

  14. MAGNETIC LIQUID DEFORMABLE MIRRORS FOR ASTRONOMICAL APPLICATIONS: ACTIVE CORRECTION OF OPTICAL ABERRATIONS FROM LOWER-GRADE OPTICS AND SUPPORT SYSTEM

    SciTech Connect

    Borra, E. F.

    2012-08-01

    Deformable mirrors are increasingly used in astronomy. However, they still are limited in stroke for active correction of high-amplitude optical aberrations. Magnetic liquid deformable mirrors (MLDMs) are a new technology that has the advantages of high-amplitude deformations and low costs. In this paper, we demonstrate extremely high strokes and interactuator strokes achievable by MLDMs which can be used in astronomical instrumentation. In particular, we consider the use of such a mirror to suggest an interesting application for the next generation of large telescopes. We present a prototype 91 actuator deformable mirror made of a magnetic liquid (ferrofluid). This mirror uses a technique that linearizes the response of such mirrors by superimposing a large and uniform magnetic field on the magnetic field produced by an array of small coils. We discuss experimental results that illustrate the performance of MLDMs. A most interesting application of MLDMs comes from the fact they could be used to correct the aberrations of large and lower optical quality primary mirrors held by simple support systems. We estimate basic parameters of the needed MLDMs, obtaining reasonable values.

  15. Corneal Pachymetry Mapping with High-speed Optical Coherence Tomography

    PubMed Central

    Li, Yan; Shekhar, Raj; Huang, David

    2006-01-01

    Objective To map corneal thickness before and after LASIK with optical coherence tomography (OCT). Design Cross-sectional observational study. Participants Forty-two eyes of 21 normal subjects undergoing LASIK. Methods A high-speed (2000 axial scans/second) 1.3-μm-wavelength corneal and anterior segment OCT prototype was used for corneal scanning. The scan pattern consisted of 10-mm radial lines on 8 meridians centered on the vertex reflection. The entire scan pattern of 1024 a-scans was acquired in 0.5 seconds. We developed automated computer processing for 3-dimensional corneal reconstruction and measurement. Corneal thickness was measured normal to the anterior surface and presented as color pachymetry maps and zonal statistics. The maps were divided into a central zone (<2 mm) and 3 annular areas (pericentral, 2–5 mm; transitional, 5–7 mm; peripheral, 7–10 mm), which were further divided into quadrantal zones. The average, minimum, and maximum corneal thicknesses were computed for zones within the 7-mm diameter. Optical coherence tomography and ultrasound pachymetry were measured 3 times at the preoperative and 3-month postoperative visits. Reproducibility was assessed by the pooled standard deviations (SDs) of the repeated measurements. Main Outcome Measures Optical coherence tomography pachymetric map and zonal statistic, and ultrasound pachymetry. Results Before LASIK, central corneal thicknesses (CCTs) were 546.9±29.4 μm (mean ± SD) for OCT and 553.3±33.0 μm for ultrasound. After LASIK, CCTs were 513.7±44.5 μm for OCT and 498±46.6 μm for ultrasound. Optical coherence tomography and ultrasound CCT were highly correlated (Pearson correlation r = 0.97 before LASIK and 0.98 afterwards). Optical coherence tomography CCT was slightly less than ultrasound CCT before surgery (mean difference, −6.4 μm; 95% limits of agreement, −23.2 to 10.4 μm) but slightly greater after LASIK (15.7 μm; −1.6 to 33 μm). These differences were statistically

  16. Design of spectrometer for high-speed line field optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Kamal, Mohammad; Narayanswamy, Sivakumar; Packirisamy, Muthukumaran

    2011-08-01

    The quality of the spectrometer affects the sensitivity fall-off, axial resolution, and depth scan range, therefore overall performance of the spectral domain optical coherence tomography (SD-OCT) imaging. Chromatic aberration, optical resolution, and detector array resolution are the key design consideration for high-quality OCT spectrometer. Traditionally refractive optics spectrometer is used in SD-OCT. In the present work, the optical design of the reflective optics spectrometer and of the refractive optics spectrometers is reported for high-speed line field optical coherence tomography imaging. The performance of the spectrometers was compared by using the ZEMAX optical design software. The ZEMAX optical modeling analysis shows that the reflective optics spectrometer provides better performance by comparison with the refractive optics spectrometer.

  17. Optical Variability of Two High-Luminosity Radio-Quiet Quasars, PDS 456 and PHL 1811

    NASA Astrophysics Data System (ADS)

    Gaskell, C. M.; Benker, A. J.; Campbell, J. S.; Crowley, K. A.; George, T. A.; Hedrick, C. H.; Hiller, M. E.; Klimek, E. S.; Leonard, J. P.; Peterson, B. W.; Sanders, K. M.

    2003-12-01

    PDS 456 and PHL 1811 are two of the highest luminosity low-redshift quasars. Both have optical luminosities comparable to 3C 273, but they have low radio luminosities. PDS 456 is a broad line object but PHL 1811 could be classified as a high-luminosity Narrow-Line Seyfert 1 (NLS1) object. We present the results of optical (V-band) continuum monitoring of PDS 456 and PHL 1811. We compare the variability properties of these two very different AGNs compared with the radio-loud AGN 3C 273, and we discuss the implications for the origin of the optical continuum variability in AGNs. This research has been supported in part by the Howard Hughes Foundation, Nebraska EPSCoR, the University of Nebraska Layman Fund, the University of Nebraska Undergraduate Creative Activities and Research Experiences, Pepsi-Cola, and the National Science Foundation through grant AST 03-07912.

  18. Characterization of gigabit ethernet over highly turbulent optical wireless links

    NASA Astrophysics Data System (ADS)

    Johnson, Gary W.; Cornish, John P.; Wilburn, Jeffrey W.; Young, Richard A.; Ruggiero, Anthony J.

    2002-12-01

    We report on the performance characterization and issues associated with using Gigabit Ethernet (GigE) over a highly turbulent 1.3 km air-optic lasercom links. Commercial GigE hardware is a cost-effective and scalable physical layer standard that can be applied to air-optic communications. We demonstrate a simple GigE hardware interface to a single-mode fiber-coupled, 1550 nm, WDM air-optic transceiver. TCP/IP serves as a robust and universal foundation protocol that has some tolerance of data loss due to atmospheric fading. Challenges include establishing and maintaining a connection with acceptable throughput under poor propagation conditions. The most useful link performance diagnostic is shown to be scintillation index, where a value of 0.2 is the maximum permissible for adequate GigE throughput. Maximum GigE throughput observed was 49.7% of that obtained with a fiber jumper when scintillation index is 0.1. Shortcomings in conventional measurements such as bit error rate are apparent. Prospects for forward error correction and other link enhancements will be discussed.

  19. Characterization of Gigabit Ethernet Over Highly Turbulent Optical Wireless Links

    SciTech Connect

    Johnson, G W; Cornish, J P; Wilburn, J W; Young, R A; Ruggiero, A J

    2002-07-01

    We report on the performance characterization and issues associated with using Gigabit Ethernet (GigE) over a highly turbulent (C{sub n}{sup 2} > 10{sup -12}) 1.3 km air-optic lasercom links. Commercial GigE hardware is a cost-effective and scalable physical layer standard that can be applied to air-optic communications. We demonstrate a simple GigE hardware interface to a singlemode fiber-coupled, 1550 nm, WDM air-optic transceiver. TCPAP serves as a robust and universal foundation protocol that has some tolerance of data loss due to atmospheric fading. Challenges include establishing and maintaining a connection with acceptable throughput under poor propagation conditions. The most useful link performance diagnostic is shown to be scintillation index, where a value of 0.2 is the maximum permissible for adequate GigE throughput. Maximum GigE throughput observed was 49.7% of that obtained with a fiber jumper when scintillation index is 0.1. Shortcomings in conventional measurements such as bit error rate are apparent. Prospects for forward mor correction and other link enhancements will be discussed.

  20. Data security in high-speed optical links

    NASA Astrophysics Data System (ADS)

    Kartalopoulos, Stamatios V.

    2005-05-01

    Wavelength Division Multiplexing (WDM) is a photonic technology capable to transport over a single fiber more than a Tbit/s aggregate traffic. Currently, WDM is the only deployed method in transcontinental and transoceanic applications. In the optical network, each fiber link consists of segments, each several kilometers long, the connecting points of which are amenable to tapping. When a small amount of optical signal is extracted from a tap, when the signal is properly amplified it can be monitored by unauthorized personnel thus threatening communications and land-security. Since each WDM channel carries traffic from one customer, it is not difficult for the connoisseur to demultiplex a specific channel, isolate a specific payload and break the encrypted datagram. Therefore, in addition to data encryption, high-speed communications security should also rely on securing the optical links. In this paper, we present a WDM link security method that, even if fiber is tapped, constitutes channel monitoring and information decrypting by an eavesdropper or unauthorized personnel virtually impossible. In addition, we describe the circuit building blocks behind the method that makes eavesdropping impossible.

  1. Behavioral Model of High Performance Camera for NIF Optics Inspection

    SciTech Connect

    Hackel, B M

    2007-08-30

    The purpose of this project was to develop software that will model the behavior of the high performance Spectral Instruments 1000 series Charge-Coupled Device (CCD) camera located in the Final Optics Damage Inspection (FODI) system on the National Ignition Facility. NIF's target chamber will be mounted with 48 Final Optics Assemblies (FOAs) to convert the laser light from infrared to ultraviolet and focus it precisely on the target. Following a NIF shot, the optical components of each FOA must be carefully inspected for damage by the FODI to ensure proper laser performance during subsequent experiments. Rapid image capture and complex image processing (to locate damage sites) will reduce shot turnaround time; thus increasing the total number of experiments NIF can conduct during its 30 year lifetime. Development of these rapid processes necessitates extensive offline software automation -- especially after the device has been deployed in the facility. Without access to the unique real device or an exact behavioral model, offline software testing is difficult. Furthermore, a software-based behavioral model allows for many instances to be running concurrently; this allows multiple developers to test their software at the same time. Thus it is beneficial to construct separate software that will exactly mimic the behavior and response of the real SI-1000 camera.

  2. An optical flameout detection system for NASA Langley's 8-Foot High Temperature Tunnel

    NASA Technical Reports Server (NTRS)

    Borg, S. E.; West, J. W.; Lawrence, R. M.; Harper, S. E.; Alderfer, D. W.; Connelly, J. M.

    1993-01-01

    A brief description is presented of an optical flameout detection system under development at NASA Langley's 8-Foot High Temperature Wind Tunnel. The system design, theory of operation, and performance are addressed. The system can respond quickly to sudden changes in combustor light intensity and is a reliable indicator of flame activity within the combustor. Deviations of the system could provide more detailed information on various aspects of the combustion process.

  3. Highly precise and robust packaging of optical components

    NASA Astrophysics Data System (ADS)

    Leers, Michael; Winzen, Matthias; Liermann, Erik; Faidel, Heinrich; Westphalen, Thomas; Miesner, Jörn; Luttmann, Jörg; Hoffmann, Dieter

    2012-03-01

    In this paper we present the development of a compact, thermo-optically stable and vibration and mechanical shock resistant mounting technique by soldering of optical components. Based on this technique a new generation of laser sources for aerospace applications is designed. In these laser systems solder technique replaces the glued and bolted connections between optical component, mount and base plate. Alignment precision in the arc second range and realization of long term stability of every single part in the laser system is the main challenge. At the Fraunhofer Institute for Laser Technology ILT a soldering and mounting technique has been developed for high precision packaging. The specified environmental boundary conditions (e.g. a temperature range of -40 °C to +50 °C) and the required degrees of freedom for the alignment of the components have been taken into account for this technique. In general the advantage of soldering compared to gluing is that there is no outgassing. In addition no flux is needed in our special process. The joining process allows multiple alignments by remelting the solder. The alignment is done in the liquid phase of the solder by a 6 axis manipulator with a step width in the nm range and a tilt in the arc second range. In a next step the optical components have to pass the environmental tests. The total misalignment of the component to its adapter after the thermal cycle tests is less than 10 arc seconds. The mechanical stability tests regarding shear, vibration and shock behavior are well within the requirements.

  4. Horizon: A Proposal for Large Aperture, Active Optics in Geosynchronous Orbit

    NASA Technical Reports Server (NTRS)

    Chesters, Dennis; Jenstrom, Del

    2000-01-01

    In 1999, NASA's New Millennium Program called for proposals to validate new technology in high-earth orbit for the Earth Observing-3 (NMP EO3) mission to fly in 2003. In response, we proposed to test a large aperture, active optics telescope in geosynchronous orbit. This would flight-qualify new technologies for both Earth and Space science: 1) a future instrument with LANDSAT image resolution and radiometric quality watching continuously from geosynchronous station, and 2) the Next Generation Space Telescope (NGST) for deep space imaging. Six enabling technologies were to be flight-qualified: 1) a 3-meter, lightweight segmented primary mirror, 2) mirror actuators and mechanisms, 3) a deformable mirror, 4) coarse phasing techniques, 5) phase retrieval for wavefront control during stellar viewing, and 6) phase diversity for wavefront control during Earth viewing. Three enhancing technologies were to be flight- validated: 1) mirror deployment and latching mechanisms, 2) an advanced microcontroller, and 3) GPS at GEO. In particular, two wavefront sensing algorithms, phase retrieval by JPL and phase diversity by ERIM International, were to sense optical system alignment and focus errors, and to correct them using high-precision mirror mechanisms. Active corrections based on Earth scenes are challenging because phase diversity images must be collected from extended, dynamically changing scenes. In addition, an Earth-facing telescope in GEO orbit is subject to a powerful diurnal thermal and radiometric cycle not experienced by deep-space astronomy. The Horizon proposal was a bare-bones design for a lightweight large-aperture, active optical system that is a practical blend of science requirements, emerging technologies, budget constraints, launch vehicle considerations, orbital mechanics, optical hardware, phase-determination algorithms, communication strategy, computational burdens, and first-rate cooperation among earth and space scientists, engineers and managers

  5. High-resolution extended source optical coherence tomography.

    PubMed

    Yu, Xiaojun; Liu, Xinyu; Chen, Si; Luo, Yuemei; Wang, Xianghong; Liu, Linbo

    2015-10-01

    High resolution optical coherence tomography (OCT) is capable of providing detailed tissue microstructures that are critical for disease diagnosis, yet its sensitivity is usually degraded since the system key components are typically not working at their respective center wavelengths. We developed a novel imaging system that achieves enhanced sensitivity without axial resolution degradation by the use of a spectrally encoded extended source (SEES) technique; it allows larger sample power without exceeding the maximum permissible exposure (MPE). In this study, we demonstrate a high-resolution extended source (HRES) OCT system, which is capable of providing a transverse resolution of 4.4 µm and an axial resolution of 2.1 µm in air with the SEES technique. We first theoretically show a sensitivity advantage of 6-dB of the HRES-OCT over that of its point source counterpart using numerical simulations, and then experimentally validate the applicability of the SEES technique to high-resolution OCT (HR-OCT) by comparing the HRES-OCT with an equivalent point-source system. In the HRES-OCT system, a dispersive prism was placed in the infinity space of the sample arm optics to spectrally extend the visual angle (angular subtense) of the light source to 10.3 mrad. This extended source allowed ~4 times larger MPE than its point source counterpart, which results in an enhancement of ~6 dB in sensitivity. Specifically, to solve the unbalanced dispersion between the sample and the reference arm optics, we proposed easy and efficient methods for system calibration and dispersion correction, respectively. With a maximum scanning speed reaching up to 60K A-lines/s, we further conducted imaging experiments with HRES-OCT using the human fingertip in vivo and the swine eye tissues ex vivo. Results demonstrate that the HRES-OCT is able to achieve significantly larger penetration depth than its conventional point source OCT counterpart.

  6. New Submerged-Robot Control Optical Fiber Cable With Small-Diameter, High-Strength Frp Covered Optical Fiber

    NASA Astrophysics Data System (ADS)

    Fuse, K.; Shirasaka, Y.; Yanagawa, H.

    1984-10-01

    Of natural resources on the earth, the utilization of the oceans has the oldest history, and the development of them has been delayed most. However, hot expectation is being placed on the development of the oceans. The element that obstructs the acceleration of such development is the sea itself. From a technical viewpoint, the means to explore the oceans have not been developed sufficiently, and equipment such as special large vehicles and ships has been bulky, requiring a very large sum of money to prepare them. These have been part of the reasons why the development of the oceans has been delayed. For this reason, a large number of exploratory systems will be studied as the ocean development becomes active in the near future. A single optical fiber cable has been considered as a cable for control of an ocean exploratory robot, which weighs approximately 30 to 40 kg at most in air requiring no power feeding to the drive section inside the vehicle and running by self on a built-in battery, as well as for data transfer. This cable is believed most suitable in terms of high speed mobility, transmission characteristics, and system cost. The mode (system) of pay off of the cable paid off by the ship loading such a cable becomes very important in the design of optical fiber cables for control of ocean exploratory robots. This paper introduces a new FRP covered optical fiber cable developed as an optical fiber cable for control of ocean exploratory robots with a small diameter and rotating motion. This cable is considered most suitable for the pay off-system which is simple and offers the highest space utility. The paper describes a basic study made prior to an actual performance test in the sea, as well as its design and characteristics.

  7. Optical power splitter for splitting high power light

    DOEpatents

    English, Jr., Ronald E.; Christensen, John J.

    1995-01-01

    An optical power splitter for the distribution of high-power light energy has a plurality of prisms arranged about a central axis to form a central channel. The input faces of the prisms are in a common plane which is substantially perpendicular to the central axis. A beam of light which is substantially coaxial to the central axis is incident on the prisms and at least partially strikes a surface area of each prism input face. The incident beam also partially passes through the central channel.

  8. Optical power splitter for splitting high power light

    DOEpatents

    English, R.E. Jr.; Christensen, J.J.

    1995-04-18

    An optical power splitter for the distribution of high-power light energy has a plurality of prisms arranged about a central axis to form a central channel. The input faces of the prisms are in a common plane which is substantially perpendicular to the central axis. A beam of light which is substantially coaxial to the central axis is incident on the prisms and at least partially strikes a surface area of each prism input face. The incident beam also partially passes through the central channel. 5 figs.

  9. Optical Emission Characterization of High-Power Hall Thruster Wear

    NASA Technical Reports Server (NTRS)

    WIlliams, George J.; Kamhawi, Hani

    2013-01-01

    Optical emission spectroscopy is employed to correlate BN insulator erosion with high-power operation of the NASA 300M Hall-effect thruster. Actinometry leveraging excited xenon states is used to normalize the emission spectra of ground state boron as a function of thruster operating condition. Trends in the strength of the boron signal are correlated with thruster power, discharge voltage, discharge current and magnetic field strength. The boron signals are shown to trend with discharge current and show weak dependence on discharge voltage. The trends are consistent with data previously collected on the NASA 300M and NASA 457M thrusters but are different from conventional wisdom.

  10. Distributed high-precision time transfer through passive optical networks

    NASA Astrophysics Data System (ADS)

    Wu, Guiling; Hu, Liang; Zhang, Hao; Chen, Jianping

    2014-09-01

    We propose a one-point to multipoint distributed time transfer through passive optical networks using a time division multiple access (TDMA) based two-way time transfer. The clock at each clock user node is, in turn, compared with the high-precision reference clock at a master node by a two-way time transfer during assigned subperiods. The corresponding TDMA control protocol and time transfer units for the proposed scheme are designed and implemented. A 1×8 experimental system with a 20 km single-mode fiber in each subpath is demonstrated. The results show that a standard deviation of <60 ps can be reached in each comparison subperiod.

  11. High speed OFDM-CDMA optical access network.

    PubMed

    Guo, X; Wang, Q; Zhou, L; Fang, L; Wonfor, A; Penty, R V; White, I H

    2016-04-15

    We demonstrate the feasibility of a 16 × 3.75 Gb/s (60 Gb/s aggregate) Orthogonal frequency division multiplexing-code division multiple access passive optical network for next-generation access applications. 3.75 Gb/s PON channel transmission over 25 km single-mode fiber shows 0.1 dB dispersion and 0.9 dB crosstalk penalties. Advantages of the system include high capacity, enhanced spectral efficiency, coding gain, and networking functions such as increased security and single-wavelength operation.

  12. High Speed Optical Tomography System for Imaging Dynamic Transparent Media

    NASA Astrophysics Data System (ADS)

    McMackin, Lenore; Hugo, Ronald J.; Pierson, R. E.; Truman, C. R.

    1997-11-01

    We describe the design and operation of a high speed optical tomography system for measuring two-dimensional images of a dynamic phase object at a rate of 5 kHz. Data from a set of eight Hartmann wavefront sensors is back-projected to produce phase images showing the details of the inner structure of a heated air flow. The tomographic reconstructions have a spatial resolution of approximately 2.0 mm and can measure temperature variations across the flow with an accuracy of about 0.7 C. Series of animated reconstructions at different downstream locations illustrate the development of flow structure and the effect of acoustic flow forcing.

  13. High speed optical links between LLNL and Berkeley

    SciTech Connect

    Lennon, W.J.; Thombley, R.L.

    1994-08-08

    The Advanced Telecommunications Program at Lawrence Livermore National Laboratory, in collaboration with Pacific Bell, is developing an experimental high speed, four wavelength, protocol independent optical link for evaluating wide area networking interconnection schemes and the use of fiber amplifiers. Lawrence Livermore National Laboratory, as a super-user, supercomputer, and super-application site, is anticipating the future bandwidth and protocol requirements to connect to other such sites as well as to connect to remote sited control centers and experiments. In this paper we discuss our vision of the future of Wide Area Networking and describe the plans for the wavelength division multiplexed link between Livermore and the University of California at Berkeley.

  14. Reflectively Coupled Waveguide Photodetector for High Speed Optical Interconnection

    PubMed Central

    Hsu*, Shih-Hsiang

    2010-01-01

    To fully utilize GaAs high drift mobility, techniques to monolithically integrate In0.53Ga0.47As p-i-n photodetectors with GaAs based optical waveguides using total internal reflection coupling are reviewed. Metal coplanar waveguides, deposited on top of the polyimide layer for the photodetector’s planarization and passivation, were then uniquely connected as a bridge between the photonics and electronics to illustrate the high-speed monitoring function. The photodetectors were efficiently implemented and imposed on the echelle grating circle for wavelength division multiplexing monitoring. In optical filtering performance, the monolithically integrated photodetector channel spacing was 2 nm over the 1,520–1,550 nm wavelength range and the pass band was 1 nm at the −1 dB level. For high-speed applications the full-width half-maximum of the temporal response and 3-dB bandwidth for the reflectively coupled waveguide photodetectors were demonstrated to be 30 ps and 11 GHz, respectively. The bit error rate performance of this integrated photodetector at 10 Gbit/s with 27-1 long pseudo-random bit sequence non-return to zero input data also showed error-free operation. PMID:22163502

  15. High-definition optical coherence tomography of melanocytic skin lesions.

    PubMed

    Gambichler, Thilo; Plura, Iris; Schmid-Wendtner, Monika; Valavanis, Konstantinos; Kulichova, Daniela; Stücker, Markus; Pljakic, Azem; Berking, Carola; Maier, Tanja

    2015-08-01

    High-definition optical coherence tomography (HD-OCT) scanners have recently been developed. We assessed micromorphological HD-OCT correlates of benign naevi (BN) and malignant melanoma (MM). 28 BN and 20 MM were studied using HD-OCT and histology. Epidermal honeycomb/cobblestone pattern, regular junctional cell nests, and edged papillae are more often observed in BN, whereas fusion of rete ridges, pagetoid cells and junctional and/or dermal nests with atypical cells are more frequently seen in MM. A high overlap of HD-OCT features in BN and MM was observed and in 20% of MM we did not find evidence for malignancy in OCT images at all. Using HD-OCT it is possible to visualize architectural and cellular alterations of melanocytic skin lesions. The overlap of HD-OCT features seen in BN and MM and the absence of suspicious HD-OCT features in some MM represents an important limitation of HD-OCT affecting the sensitivity of HD-OCT in diagnosing MM. High-definition optical coherence tomography and the corresponding vertically sectioned histology of a compound naevus. PMID:25237005

  16. High power beam profile monitor with optical transition radiation

    SciTech Connect

    Denard, J.C.; Piot, P.; Capek, K.; Feldl, E.

    1997-06-01

    A simple monitor has been built to measure the profile of the high power beam (800 kW) delivered by the CEBAF accelerator at Jefferson Lab. The monitor uses the optical part of the forward transition radiation emitted from a thin carbon foil. The small beam size to be measured, about 100 {mu}m, is challenging not only for the power density involved but also for the resolution the instrument must achieve. An important part of the beam instrumentation community believes the radiation being emitted into a cone of characteristic angle 1/{gamma} is originated from a region of transverse dimension roughly {lambda}{gamma}; thus the apparent size of the source of transition radiation would become very large for highly relativistic particles. This monitor measures 100 {mu}m beam sizes that are much smaller than the 3.2 mm {lambda}{gamma} limit; it confirms the statement of Rule and Fiorito that optical transition radiation can be used to image small beams at high energy. The present paper describes the instrument and its performance. The authors tested the foil in, up to 180 {mu}A of CW beam without causing noticeable beam loss, even at 800 MeV, the lowest CEBAF energy.

  17. High-grade optical polydimethylsiloxane for microfluidic applications.

    PubMed

    Lovchik, Robert Dean; Wolf, Heiko; Delamarche, Emmanuel

    2011-12-01

    Commercially available polydimethylsiloxane (PDMS) elastomers, such as Sylgard 184® are widely used in soft lithography and for microfluidic applications. These PDMS elastomers contain fillers to enhance their mechanical stability. The reinforcing fillers, often sub-micrometer small SiO(2) particles, tend to aggregate, swell with water, and thereby become cognoscible in a way that can strongly interfere with the visualization of micro-scale events taking place next to PDMS structures. As PDMS microfluidics are often used for studying cells and micro-/nanoparticles and for creating/handling nanodroplets, it has become highly desirable to employ a PDMS having high optical quality and that allows microscopy observation without artifacts. Here, we present a PDMS formulation that is free of fillers and has sufficiently low viscosity to perform a filtration step of the mixed prepolymers before curing. By molding a bi-layer microfluidic network (MFN), composed of a thin filler-free PDMS layer and a thicker Sylgard 184® backing layer, PDMS MFNs featuring both high optical quality and mechanical stability, can be fabricated.

  18. High-speed asynchronous optical sampling for high-sensitivity detection of coherent phonons

    NASA Astrophysics Data System (ADS)

    Dekorsy, T.; Taubert, R.; Hudert, F.; Schrenk, G.; Bartels, A.; Cerna, R.; Kotaidis, V.; Plech, A.; Köhler, K.; Schmitz, J.; Wagner, J.

    2007-12-01

    A new optical pump-probe technique is implemented for the investigation of coherent acoustic phonon dynamics in the GHz to THz frequency range which is based on two asynchronously linked femtosecond lasers. Asynchronous optical sampling (ASOPS) provides the performance of on all-optical oscilloscope and allows us to record optically induced lattice dynamics over nanosecond times with femtosecond resolution at scan rates of 10 kHz without any moving part in the set-up. Within 1 minute of data acquisition time signal-to-noise ratios better than 107 are achieved. We present examples of the high-sensitivity detection of coherent phonons in superlattices and of the coherent acoustic vibration of metallic nanoparticles.

  19. Analysis of nearly simultaneous X-ray and optical observations of active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Webb, James Raymond

    Rosemary Hill optical and EINSTEIN X-ray observations of a sample of 36 active galactic nuclei (AGN) were reduced and analyzed. Seventy-two X-ray observations of these sources were reduced, nineteen of which yielded spectral information. Of these spectral observations, significant hydrogen column densities above the galactic value were required for nine of the eleven sources which were observed more than once by EINSTEIN. Correlations between the X-ray and optical luminosities were investigated using the Jefferys method of least squares. This method allows for errors in both variables. The results indicate a strong correlation between the X-ray and optical luminosities for the entire sample. Division of the sample into groups with similar optical variability characteristics show that the less violently violent variable AGN are more highly correlated than the violently variable blazars. Infrared and radio observations were combined with the X-ray and optical observations of six AGN. These sources were modelled in terms of the synchrotron-self-Compton model. The turnover frequency falls between the infrared and radio data and reliable estimates of this parameter are difficult to estimate. Therefore the results were found as a function of the turnover frequency. Four sources required relativistic bulk motion or beaming. Multifrequency spectra made at different times for one individual source, 0235+164, required different amounts of beaming to satisfy the X-ray observations. Sizes of the emitting regions for the sources modelled ranged from 0.5 parsec to 1.0 parsec.

  20. Characterization of Fibre Channel over Highly Turbulent Optical Wireless Links

    SciTech Connect

    Johnson, G W; Henderer, B D; Wilburn, J W; Ruggiero, A J

    2003-07-28

    We report on the performance characterization and issues associated with using Fibre Channel (FC) over a highly turbulent free-space optical (FSO) link. Fibre Channel is a storage area network standard that provides high throughput with low overhead. Extending FC to FSO links would simplify data transfer from existing high-bandwidth sensors such as synthetic aperture radars and hyperspectral imagers. We measured the behavior of FC protocol at 1 Gbps in the presence of synthetic link dropouts that are typical of turbulent FSO links. Results show that an average bit error rate of less than 2 x 10{sup -8} is mandatory for adequate throughput. More importantly, 10 ns dropouts at a 2 Hz rate were sufficient to cause long (25 s) timeouts in the data transfer. Although no data was lost, this behavior is likely to be objectionable for most applications. Prospects for improvements in hardware and software will be discussed.

  1. High speed all optical shear wave imaging optical coherence elastography (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Song, Shaozhen; Hsieh, Bao-Yu; Wei, Wei; Shen, Tueng; O'Donnell, Matthew; Wang, Ruikang K.

    2016-03-01

    Optical Coherence Elastography (OCE) is a non-invasive testing modality that maps the mechanical property of soft tissues with high sensitivity and spatial resolution using phase-sensitive optical coherence tomography (PhS-OCT). Shear wave OCE (SW-OCE) is a leading technique that relies on the speed of propagating shear waves to provide a quantitative elastography. Previous shear wave imaging OCT techniques are based on repeated M-B scans, which have several drawbacks such as long acquisition time and repeated wave stimulations. Recent developments of Fourier domain mode-locked high-speed swept-source OCT system has enabled enough speed to perform KHz B-scan rate OCT imaging. Here we propose ultra-high speed, single shot shear wave imaging to capture single-shot transient shear wave propagation to perform SW-OCE. The frame rate of shear wave imaging is 16 kHz, at A-line rate of ~1.62 MHz, which allows the detection of high-frequency shear wave of up to 8 kHz. The shear wave is generated photothermal-acoustically, by ultra-violet pulsed laser, which requires no contact to OCE subjects, while launching high frequency shear waves that carries rich localized elasticity information. The image acquisition and processing can be performed at video-rate, which enables real-time 3D elastography. SW-OCE measurements are demonstrated on tissue-mimicking phantoms and porcine ocular tissue. This approach opens up the feasibility to perform real-time 3D SW-OCE in clinical applications, to obtain high-resolution localized quantitative measurement of tissue biomechanical property.

  2. Optical Properties of Active Regions in Terahertz Quantum Cascade Lasers

    NASA Astrophysics Data System (ADS)

    Dyksik, M.; Motyka, M.; Rudno-Rudziński, W.; Sęk, G.; Misiewicz, J.; Pucicki, D.; Kosiel, K.; Sankowska, I.; Kubacka-Traczyk, J.; Bugajski, M.

    2016-07-01

    In this work, AlGaAs/GaAs superlattice, with layers' sequence and compositions imitating the active and injector regions of a quantum cascade laser designed for emission in the terahertz spectral range, was investigated. Three independent absorption-like optical spectroscopy techniques were employed in order to study the band structure of the minibands formed within the conduction band. Photoreflectance measurements provided information about interband transitions in the investigated system. Common transmission spectra revealed, in the target range of intraband transitions, mainly a number of lines associated with the phonon-related processes, including two-phonon absorption. In contrast, differential transmittance realized by means of Fourier-transform spectroscopy was utilized to probe the confined states of the conduction band. The obtained energy separation between the second and third confined electron levels, expected to be predominantly contributing to the lasing, was found to be ~9 meV. The optical spectroscopy measurements were supported by numerical calculations performed in the effective mass approximation and XRD measurements for layers' width verification. The calculated energy spacings are in a good agreement with the experimental values.

  3. CHARACTERIZING THE OPTICAL VARIABILITY OF BRIGHT BLAZARS: VARIABILITY-BASED SELECTION OF FERMI ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Ruan, John J.; Anderson, Scott F.; MacLeod, Chelsea L.; Becker, Andrew C.; Davenport, James R. A.; Ivezic, Zeljko; Burnett, T. H.; Kochanek, Christopher S.; Plotkin, Richard M.; Sesar, Branimir; Stuart, J. Scott

    2012-11-20

    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 {approx}30% of {gamma}-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 {tau}, and driving amplitudes on short timescales {sigma}-circumflex. Imposing cuts on minimum {tau} and {sigma}-circumflex 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 {gamma}-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 {gamma}-ray blazars and is likely to be the {gamma}-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 {approx}3 years in the rest frame of the jet, in contrast with the {approx}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.

  4. 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.

  5. The High Energy Replicated Optics to Explore the Sun (HEROES)

    NASA Astrophysics Data System (ADS)

    Christe, S.; Shih, A. Y.; Rodriguez, M.; Cramer, A.; Garcia, I.; Gaskin, J.; Chavis, K.; Smith, L.

    2012-12-01

    Set to fly in the Fall of 2013 from Ft. Sumner, NM, the High Energy Replicated Optics to Explore the Sun (HEROES) mission is a collaboration between NASA Marshall Space Flight Center and Goddard Space Flight Center to upgrade an existing payload to make unique scientific measurements of the Sun (during the day) and astrophysical targets (at night) during a single flight. HEROES will use grazing-incidence x-ray focusing optics combined with position-sensitive detectors to make new high energy (>20 keV) observations of the Sun in order to understand particle acceleration in solar flares. The HEROES science payload consists of 8 mirror modules, housing 110 grazing incidence replicated optics, mounted on a carbon-fiber-Aluminum optical bench 6 m from a matching array of focal-plane detectors (high pressure xenon gas scintillation proportional counters). The solar science objectives for HEROES are to (1) investigate electron acceleration in the non-flaring solar corona by searching for the hard X-ray signature of energetic electrons and to (2) investigate the acceleration and transport of energetic electrons in solar flares. HEROES will image the Sun with an angular resolution of 20 arcsec (FWHM) and will have a sensitivity up to ~100 times better than RHESSI at 20 keV. During 6 hours of solar observations (a minimum requirement for a typical balloon flight), HEROES has a ~75% chance of observing at least one flare with a GOES class above C1, and a ~20% chance of at least one flare above M1. HEROES is expected to observe the faint HXR emission from electrons streaming down the legs of magnetic loops or escaping along open magnetic field lines. Information from this flight will be used to design of a new balloon payload (SuperHERO) capable of capable of observing the Sun for 2-4 weeks using a Long Duration Balloon. This mission is funded by the NASA HOPE (Hands On Project Experience) Training Opportunity awarded by the NASA Academy of Program/Project and Engineering

  6. The High Energy Replicated Optics to Explore the Sun (HEROES)

    NASA Astrophysics Data System (ADS)

    Christe, Steven; Shih, A. Y.; Rodriguez, M.; Cramer, A.; Gregory, K.; Gaskin, J.; Chavis, K.; Smith, L.; HOPE/HEROES Team

    2013-07-01

    Set to fly in the Fall of 2013 from Ft. Sumner, NM, the High Energy Replicated Optics to Explore the Sun (HEROES) mission is a collaboration between NASA Marshall Space Flight Center and Goddard Space Flight Center to upgrade an existing payload to make unique scientific measurements of the Sun (during the day) and astrophysical targets (at night) during a single flight. HEROES will use grazing-incidence x-ray focusing optics combined with position-sensitive detectors to make new high energy 20 keV to 75 keV) observations of the Sun in order to understand particle acceleration in solar flares. The HEROES science payload consists of 8 mirror modules, housing 109 grazing incidence replicated optics, mounted on a carbon-fiber-Aluminum optical bench 6 m from a matching array of focal-plane detectors (high pressure xenon gas scintillation proportional counters). HEROES will investigate electron acceleration and transport in the solar corona both in the solar flares and in the non-flaring quiet Sun. HEROES will image the Sun with an angular resolution of 20 arcsec (FWHM) and will have a sensitivity up to ~50 times better than RHESSI at 20 keV. During 6 hours of solar observations (a minimum requirement for a typical balloon flight), HEROES has a ~75% chance of observing at least one flare with a GOES class above C1, and a ~20% chance of at least one flare above M1. HEROES is expected to observe the faint HXR emission from electrons streaming down the legs of magnetic loops or escaping along open magnetic field lines. Experience on this flight will be used to design of new balloon payload (Super HERO) capable of capable of observing the Sun for 2-4 weeks using a Long Duration Balloon (LDB). This mission is funded by the NASA HOPE (Hands On Project Experience) Training Opportunity awarded by the NASA Academy of Program/Project and Engineering Leadership in partnership with NASA's Science Mission Directorate, Office of the Chief Engineer, and Office of the Chief

  7. Simultaneous all-optical manipulation and recording of neural circuit activity with cellular resolution in vivo

    PubMed Central

    Packer, Adam M.; Russell, Lloyd E.; Dalgleish, Henry W.P.; Häusser, Michael

    2016-01-01

    We describe an all-optical strategy for simultaneously manipulating and recording the activity of multiple neurons with cellular resolution in vivo. Concurrent two-photon optogenetic activation and calcium imaging is enabled by coexpression of a red-shifted opsin and a genetically encoded calcium indicator. A spatial light modulator allows tens of user-selected neurons to be targeted for spatiotemporally precise optogenetic activation, while simultaneous fast calcium imaging provides high-resolution network-wide readout of the manipulation with negligible optical crosstalk. Proof-of-principle experiments in mouse barrel cortex demonstrate interrogation of the same neuronal population during different behavioral states, and targeting of neuronal ensembles based on their functional signature. This approach extends the optogenetic toolkit beyond the specificity obtained with genetic or viral approaches, enabling high-throughput, flexible and long-term optical interrogation of functionally defined neural circuits with single-cell and single-spike resolution in the mammalian brain in vivo. PMID:25532138

  8. Towards high-resolution retinal prostheses with direct optical addressing and inductive telemetry

    NASA Astrophysics Data System (ADS)

    Ha, Sohmyung; Khraiche, Massoud L.; Akinin, Abraham; Jing, Yi; Damle, Samir; Kuang, Yanjin; Bauchner, Sue; Lo, Yu-Hwa; Freeman, William R.; Silva, Gabriel A.; Cauwenberghs, Gert

    2016-10-01

    Objective. Despite considerable advances in retinal prostheses over the last two decades, the resolution of restored vision has remained severely limited, well below the 20/200 acuity threshold of blindness. Towards drastic improvements in spatial resolution, we present a scalable architecture for retinal prostheses in which each stimulation electrode is directly activated by incident light and powered by a common voltage pulse transferred over a single wireless inductive link. Approach. The hybrid optical addressability and electronic powering scheme provides separate spatial and temporal control over stimulation, and further provides optoelectronic gain for substantially lower light intensity thresholds than other optically addressed retinal prostheses using passive microphotodiode arrays. The architecture permits the use of high-density electrode arrays with ultra-high photosensitive silicon nanowires, obviating the need for excessive wiring and high-throughput data telemetry. Instead, the single inductive link drives the entire array of electrodes through two wires and provides external control over waveform parameters for common voltage stimulation. Main results. A complete system comprising inductive telemetry link, stimulation pulse demodulator, charge-balancing series capacitor, and nanowire-based electrode device is integrated and validated ex vivo on rat retina tissue. Significance. Measurements demonstrate control over retinal neural activity both by light and electrical bias, validating the feasibility of the proposed architecture and its system components as an important first step towards a high-resolution optically addressed retinal prosthesis.

  9. CMOS Imaging Device for Optical Imaging of Biological Activities

    NASA Astrophysics Data System (ADS)

    Shishido, Sanshiro; Oguro, Yasuhiro; Noda, Toshihiko; Sasagawa, Kiyotaka; Tokuda, Takashi; Ohta, Jun

    In this paper, we propose a CMOS image sensor device placed on the brain surface or cerebral sulcus (Fig. 1). The device has a photo detector array where a single optical detector is usually used. The proposed imaging device enables the analysis which reflects a surface blood pattern in the observed area. It is also possible to improve effective sensitivity by image processing and to simplify the measurement system by the CMOS sensor device with on-chip light source. We describe the design details and characterization of proposed device. We also demonstrate detection of hemoglobin oxygenation level with external light source, imaging capability of biological activities, and image processing for sensitivity improvement is also realized.

  10. Optically Active Hybrid Materials Constructed from Helically Substituted Polyacetylenes.

    PubMed

    Zhang, Huanyu; Zhao, Biao; Deng, Jianping

    2016-04-01

    Functional materials derived from synthetic helical polymers are attracting increasing interest. Helically substituted polyacetylenes (HSPAs) are especially interesting as typical artificial helical polymers. In recent years, we designed and prepared a series of functional materials based on HSPAs and inorganic materials. The target is to establish some novel hybrid materials that combine the superior properties of both. The examined inorganic materials include silica, graphene, and magnetic Fe3 O4 nanoparticles. Such new functional materials hold great promise and are expected to find practical applications, for instance, as chiral absorbents, chiral sensors, chiral selectors for inducing enantioselective crystallization, chiral catalysts towards asymmetric catalysis, and chiral carriers for enantioselective release. The Personal Account summarizes our major achievements in preparing optically active hybrid materials. We hope it will speed up progress in chiral-related research areas.

  11. Sensor data fusion of optical and active radar data

    NASA Astrophysics Data System (ADS)

    Schultz, Johan; Gustafsson, Ulf; Crona, Torbjorn

    2004-08-01

    In this paper two different methods for fusing data from optical and active radar sensors are studied. The first method fuses data prior to feature extraction and the second method fuses data, in a more traditional way, after feature extraction. The advantage of fusing before feature extraction is that no information is lost prior to the fusion. The sensor data share one common dimension, namely azimuth, but the radar suffers from lower resolution. The algorithms are tested on real measurements from Ku- and millimeter wave radar combined with infrared or TV-camera. The study is in its initial phase and the two methods studied are simple in nature. The study aims to reveal differences between a raw data method and a feature-based method and should later result in a more complex and robust method.

  12. Gamma-radiation-induced degradation of actively pumped single-mode ytterbium-doped optical fibers

    NASA Astrophysics Data System (ADS)

    Singleton, B.; Petrosky, J.; Pochet, M.; Usechak, N. G.; Francis, S. A.

    2014-03-01

    The integration of optical components into the digital processing units of satellite subsystems has the potential to remove interconnect bottlenecks inherent to the volume, mass, complexity, reliability and crosstalk issues of copper-based interconnects. Assuming on-board high-bandwidth communications will utilize passive optical fibers as a communication channel, this work investigates the impact of gamma irradiation from a Co-60 source on both passive optical fibers and ytterbium-doped single-mode fibers operated as amplifiers for a 1060-nm light source. Standard optical patch cables were evaluated along with active Yb-doped double-clad fibers. Varied exposure times and signal transmission wavelengths were used to investigate the degradation of the fibers exposed to total doses above 100 krad (Si). The effect on the amplified signal gain was studied for the Yb-doped fibers. The increased attenuation in the fibers across a broad wavelength range in response to multiple levels of gamma radiation exposure along with the effect that the increased attenuation has on the actively pumped Yb-doped fiber amplifier performance, is discussed.

  13. Wide acceptance angle, high concentration ratio, optical collector

    NASA Technical Reports Server (NTRS)

    Kruer, Mark Arthur (Inventor)

    1990-01-01

    The invention is directed to an optical collector requiring a wide acceptance angle, and a high concentration ratio. The invention is particularly adapted for use in solar collectors of cassegrain design. The optical collector system includes a parabolic circular concave primary mirror and a hyperbolic circular convex secondary mirror. The primary mirror includes a circular hole located at its center wherein a solar collector is located. The mirrored surface of the secondary mirror has three distinct zones: a center circle, an on-axis annulus, and an off-axis section. The parabolic shape of the primary mirror is chosen so that the primary mirror reflects light entering the system on-axis onto the on-axis annulus. A substantial amount of light entering the system off-axis is reflected by the primary mirror onto either the off-axis section or onto the center circle. Subsequently, the off-axis sections reflect the off-axis light toward the solar collector. Thus, off-axis light is captured which would otherwise be lost to the system. The novelty of the system appears to lie in the configuration of the primary mirror which focuses off-axis light onto an annular portion of the secondary mirror to enable capture thereof. This feature results in wide acceptance angle and a high concentration ratio, and also compensates for the effects of non-specular reflection, and enables a cassegrain configuration to be used where such characteristics are required.

  14. Status of the PALM-3000 high order adaptive optics instrument

    NASA Astrophysics Data System (ADS)

    Burruss, Rick S.; Dekany, Richard G.; Roberts, Jennifer E.; Shelton, J. C.; Wallace, J. K.; Tesch, Jonathan A.; Palmer, Dean L.; Hale, David; Bartos, Randall; Rykoski, Kevin M.; Heffner, Carolyn M.; Eriksen, Jamey E.; Vescelus, Fred

    2014-07-01

    We report on the status of PALM-3000, the second generation adaptive optics instrument for the 5.1 meter Hale telescope at Palomar Observatory. PALM-3000 was released as a facility class instrument in October 2011, and has since been used on the Hale telescope a total of over 250 nights. In the past year, the PALM-3000 team introduced several instrument upgrades, including the release of the 32x32 pupil sampling mode which allows for correction on fainter guide stars, the upgrade of wavefront sensor relay optics, the diagnosis and repair of hardware problems, and the release of software improvements. We describe the performance of the PALM-3000 instrument as a result of these upgrades, and provide on-sky results. In the 32x32 pupil sampling mode (15.8 cm per subaperture), we have achieved K-band strehl ratios as high as 11% on a 14.4 mv star, and in the 64x64 pupil sampling mode (8.1 cm per subaperture), we have achieved K-band strehl ratios as high as 86% on stars brighter than 7th mv.

  15. Wide acceptance angle, high concentration ratio, optical collector

    NASA Astrophysics Data System (ADS)

    Kruer, Mark Arthur

    1990-03-01

    The invention is directed to an optical collector requiring a wide acceptance angle, and a high concentration ratio. The invention is particularly adapted for use in solar collectors of cassegrain design. The optical collector system includes a parabolic circular concave primary mirror and a hyperbolic circular convex secondary mirror. The primary mirror includes a circular hole located at its center wherein a solar collector is located. The mirrored surface of the secondary mirror has three distinct zones: a center circle, an on-axis annulus, and an off-axis section. The parabolic shape of the primary mirror is chosen so that the primary mirror reflects light entering the system on-axis onto the on-axis annulus. A substantial amount of light entering the system off-axis is reflected by the primary mirror onto either the off-axis section or onto the center circle. Subsequently, the off-axis sections reflect the off-axis light toward the solar collector. Thus, off-axis light is captured which would otherwise be lost to the system. The novelty of the system appears to lie in the configuration of the primary mirror which focuses off-axis light onto an annular portion of the secondary mirror to enable capture thereof. This feature results in wide acceptance angle and a high concentration ratio, and also compensates for the effects of non-specular reflection, and enables a cassegrain configuration to be used where such characteristics are required.

  16. High-performance hyperspectral imaging using virtual slit optics

    NASA Astrophysics Data System (ADS)

    Behr, Bradford B.; Meade, Jeffrey T.; Hajian, Arsen R.; Cenko, Andrew T.

    2013-05-01

    The High Throughput Virtual Slit (or HTVS) is a new optical technology which can significantly increase the throughput and resolution of a dispersive spectrometer. The HTVS is able to preserve spectrometer étendue, mitigating photon losses normally associated with a slit. Originally implemented in multimode fiber-input spectrometers, HTVS has now been shown to be broadly applicable to a wide variety of spatially scanning hyperspectral imagers and standoff sensors, enhancing their performance and unlocking new application areas. In essence, the anamorphic elements of the HTVS optical system provide a means to decouple the spatial (iFOV) and spectral resolution of nearly any HSI system. In some scenarios, HTVS can be used to achieve better spectral resolution with the same input slit width. Alternatively, the slit can be widened (to increase the collected signal) while maintaining the same spectral resolution. This newfound flexibility in optimizing critical performance parameters not only improves the performance of HSI systems in existing remote sensing contexts, but also opens up numerous new application areas which were previously inaccessible to hyperspectral techniques. This method adds substantial value to existing HSI designs, particularly in applications involving targets with large spatial extent and requiring high spectral resolution (e.g. standoff Raman spectroscopy). We present recent experimental results from our prototype HTVS pushbroom imager and discuss case studies of standoff Raman detection of hazardous materials, passive detection of faint narrowband and monochromatic sources, and optimal disentangling of target spectral signatures from the solar spectrum under daytime illumination.

  17. Optically powered active sensing system for Internet Of Things

    NASA Astrophysics Data System (ADS)

    Gao, Chen; Wang, Jin; Yin, Long; Yang, Jing; Jiang, Jian; Wan, Hongdan

    2014-10-01

    Internet Of Things (IOT) drives a significant increase in the extent and type of sensing technology and equipment. Sensors, instrumentation, control electronics, data logging and transmission units comprising such sensing systems will all require to be powered. Conventionally, electrical powering is supplied by batteries or/and electric power cables. The power supply by batteries usually has a limited lifetime, while the electric power cables are susceptible to electromagnetic interference. In fact, the electromagnetic interference is the key issue limiting the power supply in the strong electromagnetic radiation area and other extreme environments. The novel alternative method of power supply is power over fiber (PoF) technique. As fibers are used as power supply lines instead, the delivery of the power is inherently immune to electromagnetic radiation, and avoids cumbersome shielding of power lines. Such a safer power supply mode would be a promising candidate for applications in IOT. In this work, we built up optically powered active sensing system, supplying uninterrupted power for the remote active sensors and communication modules. Also, we proposed a novel maximum power point tracking technique for photovoltaic power convertors. In our system, the actual output efficiency greater than 40% within 1W laser power. After 1km fiber transmission and opto-electric power conversion, a stable electric power of 210mW was obtained, which is sufficient for operating an active sensing system.

  18. High-Power, High-Speed Electro-Optic Pockels Cell Modulator

    NASA Technical Reports Server (NTRS)

    Hawthorne, Justin; Battle, Philip

    2013-01-01

    Electro-optic modulators rely on a change in the index of refraction for the optical wave as a function of an applied voltage. The corresponding change in index acts to delay the wavefront in the waveguide. The goal of this work was to develop a high-speed, high-power waveguide- based modulator (phase and amplitude) and investigate its use as a pulse slicer. The key innovation in this effort is the use of potassium titanyl phosphate (KTP) waveguides, making the highpower, polarization-based waveguide amplitude modulator possible. Furthermore, because it is fabricated in KTP, the waveguide component will withstand high optical power and have a significantly higher RF modulation figure of merit (FOM) relative to lithium niobate. KTP waveguides support high-power TE and TM modes - a necessary requirement for polarization-based modulation as with a Pockels cell. High-power fiber laser development has greatly outpaced fiber-based modulators in terms of its maturity and specifications. The demand for high-performance nonlinear optical (NLO) devices in terms of power handling, efficiency, bandwidth, and useful wavelength range has driven the development of bulk NLO options, which are limited in their bandwidth, as well as waveguide based LN modulators, which are limited by their low optical damage threshold. Today, commercially available lithium niobate (LN) modulators are used for laser formatting; however, because of photorefractive damage that can reduce transmission and increase requirements on bias control, LN modulators cannot be used with powers over several mW, dependent on wavelength. The high-power, high-speed modulators proposed for development under this effort will enable advancements in several exciting fields including lidarbased remote sensing, atomic interferometry, free-space laser communications, and others.

  19. Spectroscopic sensing of reflection optical activity in achiral AgGaS₂.

    PubMed

    Arteaga, Oriol

    2015-09-15

    Optical activity is a fundamental effect of electrodynamics that was discovered more than 200 years ago. While optical activity is typically recognized by the rotation of the polarization of light as it propagates through a bulk medium, in certain configurations, the specular reflection of light on the surface of a material is also sensitive to its optical activity. Here, we show that the ellipsometric analysis of the light reflected at the surface of a gyrotropic but achiral crystal of AgGaS(2) allows the spectroscopic determination of its optical activity above the bandgap, where transmission methods are not applicable. This is the first clear spectroscopic determination of reflection optical activity in a crystal, and the values obtained are, to the best of our knowledge, the largest ever reported for a natural material. We also demonstrate that normal incidence transmission and reflection measurements probe different aspects of optical activity.

  20. Spectroscopic sensing of reflection optical activity in achiral AgGaS₂.

    PubMed

    Arteaga, Oriol

    2015-09-15

    Optical activity is a fundamental effect of electrodynamics that was discovered more than 200 years ago. While optical activity is typically recognized by the rotation of the polarization of light as it propagates through a bulk medium, in certain configurations, the specular reflection of light on the surface of a material is also sensitive to its optical activity. Here, we show that the ellipsometric analysis of the light reflected at the surface of a gyrotropic but achiral crystal of AgGaS(2) allows the spectroscopic determination of its optical activity above the bandgap, where transmission methods are not applicable. This is the first clear spectroscopic determination of reflection optical activity in a crystal, and the values obtained are, to the best of our knowledge, the largest ever reported for a natural material. We also demonstrate that normal incidence transmission and reflection measurements probe different aspects of optical activity. PMID:26371915

  1. Optically assisted trapping with high-permittivity dielectric rings: Towards optical aerosol filtration

    DOE PAGES

    Alaee, Rasoul; Kadic, Muamer; Rockstuhl, Carsten; Passian, Ali

    2016-10-04

    Controlling the transport, trapping, and filtering of nanoparticles is important for many applications. By virtue of their weak response to gravity and their thermal motion, various physical mechanisms can be exploited for such operations on nanoparticles. However, the manipulation based on optical forces is potentially most appealing since it constitutes a highly deterministic approach. Plasmonic nanostructures have been suggested for this purpose, but they possess the disadvantages of locally generating heat and trapping the nanoparticles directly on the surface. Here, we propose the use of dielectric rings made of high permittivity materials for trapping nanoparticles. Thanks to their ability tomore » strongly localize the field in space, nanoparticles can be trapped without contact. We use a semianalytical method to study the ability of these rings to trap nanoparticles. Lastly, the results are supported by full-wave simulations and application of the trapping concept to nanoparticle filtration is suggested.« less

  2. Optically assisted trapping with high-permittivity dielectric rings: Towards optical aerosol filtration

    NASA Astrophysics Data System (ADS)

    Alaee, Rasoul; Kadic, Muamer; Rockstuhl, Carsten; Passian, Ali

    2016-10-01

    Controlling the transport, trapping, and filtering of nanoparticles is important for many applications. By virtue of their weak response to gravity and their thermal motion, various physical mechanisms can be exploited for such operations on nanoparticles. However, the manipulation based on optical forces is potentially most appealing since it constitutes a highly deterministic approach. Plasmonic nanostructures have been suggested for this purpose, but they possess the disadvantages of locally generating heat and trapping the nanoparticles directly on the surface. Here, we propose the use of dielectric rings made of high permittivity materials for trapping nanoparticles. Thanks to their ability to strongly localize the field in space, nanoparticles can be trapped without contact. We use a semi-analytical method to study the ability of these rings to trap nanoparticles. The results are supported by full-wave simulations. Application of the trapping concept to nanoparticle filtration is suggested.

  3. The addition of high magnifying endoscopy improves rates of high confidence optical diagnosis of colorectal polyps

    PubMed Central

    Iwatate, Mineo; Sano, Yasushi; Hattori, Santa; Sano, Wataru; Hasuike, Noriaki; Ikumoto, Taro; Kotaka, Masahito; Murakami, Yoshitaka; Hewett, David G.; Soetikno, Roy; Kaltenbach, Tonya; Fujimori, Takahiro

    2015-01-01

    Background and study aims: The real-time optical diagnosis of colorectal polyps with high confidence predictions can achieve high levels of accuracy. Increasing the rates of high confidence optical diagnosis can improve the clinical application of real-time optical diagnosis in routine practice. The primary aim of this prospective study was to evaluate whether high magnifying endoscopy improves the rates of high confidence narrow-band imaging (NBI) – based optical diagnosis for differentiating between neoplastic and non-neoplastic colorectal lesions according to the NBI international colorectal endoscopic (NICE) classification. Patients and methods: Consecutive adult patients undergoing colonoscopy with a high magnifying (maximum, × 80) colonoscope between April and August 2012 were recruited. The optical diagnosis for each polyp was evaluated during colonoscopy in two consecutive stages by the same endoscopist, who first used NBI with non-magnifying endoscopy (NBI-NME), then NBI with magnifying endoscopy (NBI-ME). A level of confidence was assigned to each prediction. Results: The analysis included 124 patients (mean age, 56.4 years; male-to-female ratio, 72:52) with 248 polyps smaller than 10 mm. Of the 248 polyps, 210 were 1 to 5 mm in size and 38 were 6 to 9 mm in size; 77 polyps were hyperplastic, 4 were sessile serrated adenomas/polyps, 160 were low grade adenomas, 5 were high grade adenomas, and 2 were deep submucosal invasive carcinomas. The rate of high confidence optical diagnosis when NBI-ME was used was significantly higher than the rate when NBI-NME was used for diminutive (1 – 5 mm) polyps (92.9 % vs 79.5 %, P < 0.001) and for small (6 – 9 mm) polyps (94.7 % vs 84.2 %, P = 0.048). Conclusion: High magnifying endoscopy significantly improved the rates of high confidence NBI-based optical diagnosis of diminutive and small colorectal polyps. Study registration: UMIN 000007608 PMID:26135657

  4. Rapid optical determination of β-lactamase and antibiotic activity

    PubMed Central

    2014-01-01

    Background The absence of rapid tests evaluating antibiotic susceptibility results in the empirical prescription of antibiotics. This can lead to treatment failures due to escalating antibiotic resistance, and also furthers the emergence of drug-resistant bacteria. This study reports a rapid optical method to detect β-lactamase and thereby assess activity of β-lactam antibiotics, which could provide an approach for targeted prescription of antibiotics. The methodology is centred on a fluorescence quenching based probe (β-LEAF – β-Lactamase Enzyme Activated Fluorophore) that mimics the structure of β-lactam antibiotics. Results The β-LEAF assay was performed for rapid determination of β-lactamase production and activity of β-lactam antibiotic (cefazolin) on a panel of Staphylococcus aureus ATCC strains and clinical isolates. Four of the clinical isolates were determined to be lactamase producers, with the capacity to inactivate cefazolin, out of the twenty-five isolates tested. These results were compared against gold standard methods, nitrocefin disk test for β-lactamase detection and disk diffusion for antibiotic susceptibility, showing results to be largely consistent. Furthermore, in the sub-set of β-lactamase producers, it was demonstrated and validated that multiple antibiotics (cefazolin, cefoxitin, cefepime) could be assessed simultaneously to predict the antibiotic that would be most active for a given bacterial isolate. Conclusions The study establishes the rapid β-LEAF assay for β-lactamase detection and prediction of antibiotic activity using S. aureus clinical isolates. Although the focus in the current study is β-lactamase-based resistance, the overall approach represents a broad diagnostic platform. In the long-term, these studies form the basis for the development of assays utilizing a broader variety of targets, pathogens and drugs. PMID:24708478

  5. Model of Atmospheric Links on Optical Communications from High Altitude

    NASA Technical Reports Server (NTRS)

    Subich, Christopher

    2004-01-01

    Optical communication links have the potential to solve many of the problems of current radio and microwave links to satellites and high-altitude aircraft. The higher frequency involved in optical systems allows for significantly greater signal bandwidth, and thus information transfer rate, in excess of 10 Gbps, and the highly directional nature of laser-based signals eliminates the need for frequency-division multiplexing seen in radio and microwave links today. The atmosphere, however, distorts an optical signal differently than a microwave signal. While the ionosphere is one of the most significant sources of noise and distortion in a microwave or radio signal, the lower atmosphere affects an optical signal more significantly. Refractive index fluctuations, primarily caused by changes in atmospheric temperature and density, distort the incoming signal in both deterministic and nondeterministic ways. Additionally, suspended particles, such as those in haze or rain, further corrupt the transmitted signal. To model many of the atmospheric effects on the propagating beam, we use simulations based on the beam-propagation method. This method, developed both for simulation of signals in waveguides and propagation in atmospheric turbulence, separates the propagation into a diffraction and refraction problem. The diffraction step is an exact solution, within the limits of numerical precision, to the problem of propagation in free space, and the refraction step models the refractive index variances over a segment of the propagation path. By applying refraction for a segment of the propagation path, then diffracting over that same segment, this method forms a good approximation to true propagation through the atmospheric medium. Iterating over small segments of the total propagation path gives a good approximation to the problem of propagation over the entire path. Parameters in this model, such as initial beam profile and atmospheric constants, are easily modified in a

  6. LGSD/NGSD: high speed optical CMOS imagers for E-ELT adaptive optics

    NASA Astrophysics Data System (ADS)

    Downing, Mark; Kolb, Johann; Balard, Philippe; Dierickx, Bart; Defernez, Arnaud; Feautrier, Philippe; Finger, Gert; Fryer, Martin; Gach, Jean-Luc; Guillaume, Christian; Hubin, Norbert; Jerram, Paul; Jorden, Paul; Meyer, Manfred; Payne, Andrew; Pike, Andrew; Reyes, Javier; Simpson, Robert; Stadler, Eric; Stent, Jeremy; Swift, Nick

    2014-07-01

    The success of the next generation of instruments for ELT class telescopes will depend upon improving the image quality by exploiting sophisticated Adaptive Optics (AO) systems. One of the critical components of the AO systems for the E-ELT has been identified as the optical Laser/Natural Guide Star WFS detector. The combination of large format, 1760×1680 pixels to finely sample the wavefront and the spot elongation of laser guide stars, fast frame rate of 700 frames per second (fps), low read noise (< 3e-), and high QE (> 90%) makes the development of this device extremely challenging. Design studies concluded that a highly integrated Backside Illuminated CMOS Imager built on High Resistivity silicon as the most likely technology to succeed. Two generations of the CMOS Imager are being developed: a) the already designed and manufactured NGSD (Natural Guide Star Detector), a quarter-sized pioneering device of 880×840 pixels capable of meeting first light needs of the E-ELT; b) the LGSD (Laser Guide Star Detector), the larger full size device. The detailed design is presented including the approach of using massive parallelism (70,400 ADCs) to achieve the low read noise at high pixel rates of ~3 Gpixel/s and the 88 channel LVDS 220Mbps serial interface to get the data off-chip. To enable read noise closer to the goal of 1e- to be achieved, a split wafer run has allowed the NGSD to be manufactured in the more speculative, but much lower read noise, Ultra Low Threshold Transistors in the unit cell. The NGSD has come out of production, it has been thinned to 12μm, backside processed and packaged in a custom 370pin Ceramic PGA (Pin Grid Array). First results of tests performed both at e2v and ESO are presented.

  7. High Resolution Optical Surface Investigation based on Heterodyne Interferometry

    NASA Astrophysics Data System (ADS)

    Spannagel, Ruven; Schuldt, Thilo; Braxmaier, Claus

    2012-07-01

    We present results on high precision optical profilometry for investigating reflecting surfaces with respect to surface properties such as structure, roughness, and waviness. Our metrology system is based on a highly symmetric heterodyne interferometer with a potential sensitivity at the picometer level. The profilometer is capable of scanning surfaces by actuating either the device under test (DUT), or the measurement laser beam of the interferometer. The current setup with DUT-actuation has a sensitivity of about 1 nm/ ? , and achives a measurement accuracy better than 5 nm at a measurement range of 100 μm with a lateral resolution of approximately 15 μm. Different profiles of various surfaces were measured and the reproducibility of the results have been demonstrated by measuring a reference surface.

  8. High-Speed Flexible Optical Disk for Broadcast Archival Storage

    NASA Astrophysics Data System (ADS)

    Koide, Daiichi; Kajiyama, Takeshi; Tokumaru, Haruki; Takano, Yoshimichi; Onagi, Nobuaki; Aman, Yasutomo; Ohishi, Kiyoshi

    2010-08-01

    We developed a prototype of a flexible optical disk (FOD) drive with a mechanical stabilizer. We prepared the FOD that had a high recording sensitivity of a recording layer and had low byte error rates below 2 ×10-4 at speeds from 36 to 252 Mbps, and examined the recording of video data on the FOD and the drive. We could record and play a high-definition television (HDTV) video (MPEG-2, 422P@HL) seamlessly at 144 Mbps over the entire area of the FOD and the FOD drive with broadcast video systems. We confirmed that the FOD and the FOD drive can record and play HDTV signals for professional broadcast use.

  9. Compact Tb doped fiber optic current sensor with high sensitivity.

    PubMed

    Huang, Duanni; Srinivasan, Sudharsanan; Bowers, John E

    2015-11-16

    A highly sensitive fiber optic current sensor using terbium doped fiber is presented. The Verdet constant of the terbium doped fiber at 1300nm is found to be 19.5μrad/A using both a polarimetric and interferometric type sensor. Measurements on a Sagnac-loop sensor using 10cm of terbium doped fiber placed inside a solenoid show over 40dB of open loop dynamic range as well as a minimum detectable current of 0.1mA. Extrapolations of our measurements show that in a practical setup with Tb fiber wrapped around a current carrying wire, the optimal configuration is a 0.5m piece of Tb fiber with a noise limit of 22mA/√Hz. This sensor is promising for current sensing applications that require high sensitivity and small size, weight, and power. PMID:26698480

  10. High-dimensional modulation for coherent optical communications systems.

    PubMed

    Millar, David S; Koike-Akino, Toshiaki; Arık, Sercan Ö; Kojima, Keisuke; Parsons, Kieran; Yoshida, Tsuyoshi; Sugihara, Takashi

    2014-04-01

    In this paper, we examine the performance of several modulation formats in more than four dimensions for coherent optical communications systems. We compare two high-dimensional modulation design methodologies based on spherical cutting of lattices and block coding of a 'base constellation' of binary phase shift keying (BPSK) on each dimension. The performances of modulation formats generated with these methodologies is analyzed in the asymptotic signal-to-noise ratio regime and for an additive white Gaussian noise (AWGN) channel. We then study the application of both types of high-dimensional modulation formats to standard single-mode fiber (SSMF) transmission systems. For modulation with spectral efficiencies comparable to dual-polarization (DP-) BPSK, polarization-switched quaternary phase shift keying (PS-QPSK) and DP-QPSK, we demonstrate SNR gains of up to 3 dB, 0.9 dB and 1 dB respectively, at a BER of 10(-3).

  11. High-fidelity linear optical quantum computing with polarization encoding

    SciTech Connect

    Spedalieri, Federico M.; Lee, Hwang; Dowling, Jonathan P.

    2006-01-15

    We show that the KLM scheme [Knill, Laflamme, and Milburn, Nature 409, 46 (2001)] can be implemented using polarization encoding, thus reducing the number of path modes required by half. One of the main advantages of this new implementation is that it naturally incorporates a loss detection mechanism that makes the probability of a gate introducing a non-detected error, when non-ideal detectors are considered, dependent only on the detector dark-count rate and independent of its efficiency. Since very low dark-count rate detectors are currently available, a high-fidelity gate (probability of error of order 10{sup -6} conditional on the gate being successful) can be implemented using polarization encoding. The detector efficiency determines the overall success probability of the gate but does not affect its fidelity. This can be applied to the efficient construction of optical cluster states with very high fidelity for quantum computing.

  12. High sensitivity optical waveguide accelerometer based on Fano resonance.

    PubMed

    Wan, Fenghua; Qian, Guang; Li, Ruozhou; Tang, Jie; Zhang, Tong

    2016-08-20

    An optical waveguide accelerometer based on tunable asymmetrical Fano resonance in a ring-resonator-coupled Mach-Zehnder interferometer (MZI) is proposed and analyzed. A Fano resonance accelerometer has a relatively large workspace of coupling coefficients with high sensitivity, which has potential application in inertial navigation, missile guidance, and attitude control of satellites. Due to the interference between a high-Q resonance pathway and a coherent background pathway, a steep asymmetric line shape is generated, which greatly improves the sensitivity of this accelerometer. The sensitivity of the accelerometer is about 111.75 mW/g. A 393-fold increase in sensitivity is achieved compared with a conventional MZI accelerometer and is approximately equal to the single ring structure.

  13. Read-only high accuracy volume holographic optical correlator

    NASA Astrophysics Data System (ADS)

    Zhao, Tian; Li, Jingming; Cao, Liangcai; He, Qingsheng; Jin, Guofan

    2011-10-01

    A read-only volume holographic correlator (VHC) is proposed. After the recording of all of the correlation database pages by angular multiplexing, a stand-alone read-only high accuracy VHC will be separated from the VHC recording facilities which include the high-power laser and the angular multiplexing system. The stand-alone VHC has its own low power readout laser and very compact and simple structure. Since there are two lasers that are employed for recording and readout, respectively, the optical alignment tolerance of the laser illumination on the SLM is very sensitive. The twodimensional angular tolerance is analyzed based on the theoretical model of the volume holographic correlator. The experimental demonstration of the proposed read-only VHC is introduced and discussed.

  14. Thermal effects in high average power optical parametric amplifiers.

    PubMed

    Rothhardt, Jan; Demmler, Stefan; Hädrich, Steffen; Peschel, Thomas; Limpert, Jens; Tünnermann, Andreas

    2013-03-01

    Optical parametric amplifiers (OPAs) have the reputation of being average power scalable due to the instantaneous nature of the parametric process (zero quantum defect). This Letter reveals serious challenges originating from thermal load in the nonlinear crystal caused by absorption. We investigate these thermal effects in high average power OPAs based on beta barium borate. Absorption of both pump and idler waves is identified to contribute significantly to heating of the nonlinear crystal. A temperature increase of up to 148 K with respect to the environment is observed and mechanical tensile stress up to 40 MPa is found, indicating a high risk of crystal fracture under such conditions. By restricting the idler to a wavelength range far from absorption bands and removing the crystal coating we reduce the peak temperature and the resulting temperature gradient significantly. Guidelines for further power scaling of OPAs and other nonlinear devices are given.

  15. Thermal effects in high average power optical parametric amplifiers.

    PubMed

    Rothhardt, Jan; Demmler, Stefan; Hädrich, Steffen; Peschel, Thomas; Limpert, Jens; Tünnermann, Andreas

    2013-03-01

    Optical parametric amplifiers (OPAs) have the reputation of being average power scalable due to the instantaneous nature of the parametric process (zero quantum defect). This Letter reveals serious challenges originating from thermal load in the nonlinear crystal caused by absorption. We investigate these thermal effects in high average power OPAs based on beta barium borate. Absorption of both pump and idler waves is identified to contribute significantly to heating of the nonlinear crystal. A temperature increase of up to 148 K with respect to the environment is observed and mechanical tensile stress up to 40 MPa is found, indicating a high risk of crystal fracture under such conditions. By restricting the idler to a wavelength range far from absorption bands and removing the crystal coating we reduce the peak temperature and the resulting temperature gradient significantly. Guidelines for further power scaling of OPAs and other nonlinear devices are given. PMID:23455291

  16. High sensitivity optical waveguide accelerometer based on Fano resonance.

    PubMed

    Wan, Fenghua; Qian, Guang; Li, Ruozhou; Tang, Jie; Zhang, Tong

    2016-08-20

    An optical waveguide accelerometer based on tunable asymmetrical Fano resonance in a ring-resonator-coupled Mach-Zehnder interferometer (MZI) is proposed and analyzed. A Fano resonance accelerometer has a relatively large workspace of coupling coefficients with high sensitivity, which has potential application in inertial navigation, missile guidance, and attitude control of satellites. Due to the interference between a high-Q resonance pathway and a coherent background pathway, a steep asymmetric line shape is generated, which greatly improves the sensitivity of this accelerometer. The sensitivity of the accelerometer is about 111.75 mW/g. A 393-fold increase in sensitivity is achieved compared with a conventional MZI accelerometer and is approximately equal to the single ring structure. PMID:27556984

  17. Optical Fiber Strain Instrumentation for High Temperature Aerospace Structural Monitoring

    NASA Technical Reports Server (NTRS)

    Wang, A.

    2002-01-01

    The objective of the program is the development and laboratory demonstration of sensors based on silica optical fibers for measurement of high temperature strain for aerospace materials evaluations. A complete fiber strain sensor system based on white-light interferometry was designed and implemented. An experiment set-up was constructed to permit testing of strain measurement up to 850 C. The strain is created by bending an alumina cantilever beam to which is the fiber sensor is attached. The strain calibration is provided by the application of known beam deflections. To ensure the high temperature operation capability of the sensor, gold-coated single-mode fiber is used. Moreover, a new method of sensor surface attachment which permits accurate sensor gage length determination is also developed. Excellent results were obtained at temperatures up to 800-850 C.

  18. Highly luminescent garnets for magneto-optical photonic crystals

    NASA Astrophysics Data System (ADS)

    Grishin, A. M.; Khartsev, S. I.

    2009-09-01

    We compare luminescent properties of several Er-doped garnets as building blocks in all-garnet heteroepitaxial magneto-optical photonic crystals. Pulsed laser deposited La3Ga5O12, Gd3Ga5O12, Y3Fe5O12, and rf-magnetron sputtered Bi3Fe5O12 were chosen to host Er3+ ions on dodecahedral lattice sites. Er substituents with the concentration of 0.5 at. % (0.1 garnet formula units) do not decrease giant Faraday rotation in Bi2.9Er0.1Fe5O12 garnet; meanwhile providing intense room temperature C-band photoluminescence (PL). Fe3+ ion works as a sensitizer for Er resulting in fivefold PL enhancement in iron garnets compared to gallium ones. PL lifetime in gallium garnets is in millisecond range reaching almost 6 ms in Gd2.9Er0.1Ga5O12. We conclude Er substitution in gallium and iron garnet layers used both as Bragg mirrors and microcavities promises magneto-optical photonic crystals to become an active lasing medium.

  19. Optical Fiber High Temperature Sensor Instrumentation for Energy Intensive Industries

    SciTech Connect

    Cooper, Kristie L.; Wang, Anbo; Pickrell, Gary R.

    2006-11-14

    This report summarizes technical progress during the program “Optical Fiber High Temperature Sensor Instrumentation for Energy Intensive Industries”, performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The objective of this program was to use technology recently invented at Virginia Tech to develop and demonstrate the application of self-calibrating optical fiber temperature and pressure sensors to several key energy-intensive industries where conventional, commercially available sensors exhibit greatly abbreviated lifetimes due primarily to environmental degradation. A number of significant technologies were developed under this program, including • a laser bonded silica high temperature fiber sensor with a high temperature capability up to 700°C and a frequency response up to 150 kHz, • the world’s smallest fiber Fabry-Perot high temperature pressure sensor (125 x 20 μm) with 700°C capability, • UV-induced intrinsic Fabry-Perot interferometric sensors for distributed measurement, • a single crystal sapphire fiber-based sensor with a temperature capability up to 1600°C. These technologies have been well demonstrated and laboratory tested. Our work plan included conducting major field tests of these technologies at EPRI, Corning, Pratt & Whitney, and Global Energy; field validation of the technology is critical to ensuring its usefulness to U.S. industries. Unfortunately, due to budget cuts, DOE was unable to follow through with its funding commitment to support Energy Efficiency Science Initiative projects and this final phase was eliminated.

  20. Design guidelines for high dimensional stability of CFRP optical bench

    NASA Astrophysics Data System (ADS)

    Desnoyers, Nichola; Boucher, Marc-André; Goyette, Philippe

    2013-09-01

    In carbon fiber reinforced plastic (CFRP) optomechanical structures, particularly when embodying reflective optics, angular stability is critical. Angular stability or warping stability is greatly affected by moisture absorption and thermal gradients. Unfortunately, it is impossible to achieve the perfect laminate and there will always be manufacturing errors in trying to reach a quasi-iso laminate. Some errors, such as those related to the angular position of each ply and the facesheet parallelism (for a bench) can be easily monitored in order to control the stability more adequately. This paper presents warping experiments and finite-element analyses (FEA) obtained from typical optomechanical sandwich structures. Experiments were done using a thermal vacuum chamber to cycle the structures from -40°C to 50°C. Moisture desorption tests were also performed for a number of specific configurations. The selected composite material for the study is the unidirectional prepreg from Tencate M55J/TC410. M55J is a high modulus fiber and TC410 is a new-generation cyanate ester designed for dimensionally stable optical benches. In the studied cases, the main contributors were found to be: the ply angular errors, laminate in-plane parallelism (between 0° ply direction of both facesheets), fiber volume fraction tolerance and joints. Final results show that some tested configurations demonstrated good warping stability. FEA and measurements are in good agreement despite the fact that some defects or fabrication errors remain unpredictable. Design guidelines to maximize the warping stability by taking into account the main dimensional stability contributors, the bench geometry and the optical mount interface are then proposed.