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Sample records for achromatic phase shifter

  1. A new concept of achromatic phase shifter for nulling interferometry

    NASA Astrophysics Data System (ADS)

    Rouan, Daniel; Pelat, D.; Ygouf, Marie; Reess, Jean-Michel; Chemla, Fanny; Riaud, Pierre

    2007-09-01

    Direct detection and characterization of a planet around a star by nulling interferometry, must be efficient in a large wavelength domain in order to detect simultaneously the infrared bio-tracers CO II, O 3 and H IIO. This condition requires that an achromatic phase shift of π be implemented, with an accuracy sufficient for achieving a deep nulling at all considered wavelengths. Several solutions have been presented. We present here a new concept for designing such an achromatic phase shifter. It is based on two cellular mirrors (alternatively, transparent plates can be used) where cells have thickness which are respectively odd and even multiples of a quarter of the central wavelength. Each cell introduces then a phase shift of (2k + 1)π or of 2kπ, on the fraction of the wave it reflects. Each mirror is introduced in the collimated beam issued from one or the other telescopes. Because of the odd/even distribution, a destructive interference is obviously produced on axis for the central wavelength when recombining the two beams. The trick to obtain a quasi-achromatisation is to distribute the thickness of the cells, so that the nulling is also efficient for a wavelength not too far from the central wavelength. We show that if the thicknesses are distributed according to the Pascal triangle, a fair quasi-achromatism is reached. This effect is the more efficient that the number of cells is large. For instance, with 256 × 256 cells, where phase shift range is between -6π and +6π one shows that the nulling reaches 10 -6 on the wavelength range [0.7λ 0, 1.3λ 0] which corresponds roughly to the DARWIN specification. In a second step, we study the optimum way to distribute the cells in the plane of the pupil. The most important criterion is the isolation of the planet image from the residual image of the star. Several efficient configurations are presented. Finally we consider some practical aspects on a device belonging to the real world and on the bench we are

  2. Broadband Achromatic Phase Shifter for a Nulling Interferometer

    NASA Technical Reports Server (NTRS)

    Bolcar, Matthew R.; Lyon, Richard G.

    2011-01-01

    Nulling interferometry is a technique for imaging exoplanets in which light from the parent star is suppressed using destructive interference. Light from the star is divided into two beams and a phase shift of radians is introduced into one of the beams. When the beams are recombined, they destructively interfere to produce a deep null. For monochromatic light, this is implemented by introducing an optical path difference (OPD) between the two beams equal to lambda/2, where lambda is the wavelength of the light. For broadband light, however, a different phase shift will be introduced at each wavelength and the two beams will not effectively null when recombined. Various techniques have been devised to introduce an achromatic phase shift a phase shift that is uniform across a particular bandwidth. One popular technique is to use a series of dispersive elements to introduce a wavelength-dependent optical path in one or both of the arms of the interferometer. By intelligently choosing the number, material and thickness of a series of glass plates, a nearly uniform, arbitrary phase shift can be introduced between two arms of an interferometer. There are several constraints that make choosing the number, type, and thickness of materials a difficult problem, such as the size of the bandwidth to be nulled. Several solutions have been found for bandwidths on the order of 20 to 30 percent (Delta(lambda)/lambda(sub c)) in the mid-infrared region. However, uniform phase shifts over a larger bandwidth in the visible regime between 480 to 960 nm (67 percent) remain difficult to obtain at the tolerances necessary for exoplanet detection. A configuration of 10 dispersive glass plates was developed to be used as an achromatic phase shifter in nulling interferometry. Five glass plates were placed in each arm of the interferometer and an additional vacuum distance was also included in the second arm of the interferometer. This configuration creates a phase shift of pi radians with

  3. Experimental evaluation of achromatic phase shifters for mid-infrared starlight suppression.

    PubMed

    Gappinger, Robert O; Diaz, Rosemary T; Ksendzov, Alexander; Lawson, Peter R; Lay, Oliver P; Liewer, Kurt M; Loya, Frank M; Martin, Stefan R; Serabyn, Eugene; Wallace, James K

    2009-02-10

    Phase shifters are a key component of nulling interferometry, one of the potential routes to enabling the measurement of faint exoplanet spectra. Here, three different achromatic phase shifters are evaluated experimentally in the mid-infrared, where such nulling interferometers may someday operate. The methods evaluated include the use of dispersive glasses, a through-focus field inversion, and field reversals on reflection from antisymmetric flat-mirror periscopes. All three approaches yielded deep, broadband, mid-infrared nulls, but the deepest broadband nulls were obtained with the periscope architecture. In the periscope system, average null depths of 4x10(-5) were obtained with a 25% bandwidth, and 2x10(-5) with a 20% bandwidth, at a central wavelength of 9.5 mum. The best short term nulls at 20% bandwidth were approximately 9x10(-6), in line with error budget predictions and the limits of the current generation of hardware. PMID:19209197

  4. The achromatic chessboard, a new concept of a phase shifter for nulling interferometry: IV. Advanced experimental measurements

    NASA Astrophysics Data System (ADS)

    Pickel, Damien; Rouan, Daniel; Pelat, Didier; Reess, Jean-Michel; Dupuis, Olivier; Chemla, Fanny; Cohen, Mathieu

    2012-09-01

    Context. To characterize their atmospheres in order to find evidences of life, one has to detect directly photons from the exoplanets to measure their spectra. One possible technique is dark fringe interferometry that needs an achromatic π phase shift in one arm of the interferometer. We have conceived a phase shifter made of two cellular mirrors, in which each cell position and phase shift is specific, so that the behaviour of the nulling with respect to wavelength is flat within a broad range. Aims. We want to validate experimentally two versions of this achromatic phase shifter: a transmissive one in bulk optics and a reflective one using a segmented deformable mirror. What we present in this paper are the last results obtained in the lab. Methods. We built an optical bench in the visible that allows us to test the principle and characterize the performances and the limits of this phase shifter. Results. We tested several transmissive and one reflective phase shifter and obtained, for instance, an attenuation of about 2.10-3 for a white source (from 430 to 830 nm) that proved the achromatic behavior of the phase shifter. The preliminary performances and limitations are analyzed.

  5. The achromatic chessboard, a new concept of a phase shifter for nulling interferometry. I. Theory

    NASA Astrophysics Data System (ADS)

    Rouan, D.; Pelat, D.

    2008-06-01

    Context: Direct detection of a planet around a star and its characterisation for identification of bio-tracers in the mid-IR requires a nulling interferometer. Such an instrument must be efficient in a large wavelength domain in order to have the capability of simultaneously detecting the infrared spectral features of several bio-tracers: CO{2}, O{3}, and H{2}O. Aims: A broad wavelength range can be effective provided that an achromatic phase shift of π can be implemented, with good enough accuracy to achieve a deep nulling at all considered wavelengths. A new design concept for such an achromatic phase shifter is presented here. The major interest of this solution is that it allows a simple design with only one device per beam. Methods: The heart of the system consists in two cellular mirrors where each cell has a thickness that introduces, for a given central wavelength, a phase shift of (2k + 1)π or of 2k π on the fraction of the wave it reflects. Each mirror is put in one of the collimated beams of the interferometer. Because of the odd/even distribution, a destructive interference is produced on axis for the central wavelength when recombining the two beams. If the number of cells of a given thickness follows a rather simple law based on the Pascal's triangle, we then show that the nulling is also efficient for a wavelength that is not too far from the central wavelength. Results: The effect of achromatization is more efficient the more cells there are. For instance, with two mirrors of 64 × 64 cells, where the cells' phase shift ranges between -6π and +6π, one reaches a nulling of 10-6 on a wavelength range [0.6 λ0, 1.25λ0], i.e. on more than one complete octave. This is why we claim that this device produces a quasi-achromatic phase shift ; especially, it could satisfy the specifications of a space mission as DARWIN. In a second step, we study the optimum way to distribute the cells in the plane of the pupil. The most important criterion is the

  6. The achromatic chessboard, a new concept of a phase shifter for nulling interferometry. V. Experimental demonstration and performance

    NASA Astrophysics Data System (ADS)

    Pickel, D.; Pelat, D.; Rouan, D.; Reess, J.-M.; Chemla, F.; Cohen, M.; Dupuis, O.

    2013-10-01

    Context. To find evidence one day of life on extra solar planets, one will have to directly detect photons of the exoplanet to obtain spectra and to look for specific spectroscopic features. One possible technique is dark fringe interferometry with several telescopes in space. This type of interferometry requires an achromatic π phase shift in one arm of an interferometer. We have already presented a concept of a quasi-achromatic phase shifter that is made of two cellular mirrors in which each cell position and phase shift is specific, so that the behavior of the null depth as a function of the wavelength is flat within a broad range. Aims: We want to experimentally validate this concept of an achromatic phase shifter and measure its performance in two different cases: a transmissive mask, which is made in bulk optics that are machined with ion etching and a reflective one, which is made by using a commercial segmented deformable mirror that is properly controlled. Methods: We assembled a dedicated optical bench, nicknamed DAMNED, to assess the concept and characterize its performance in the visible and to determine the limitations of this phase shifter. We analyze its performance by comparing the experimental results with a numerical instrument model. Results: We tested several transmissive masks and a reflective one. We reached an attenuation of about 2 × 10-3 with a white source (Δλ = 430 to 830 nm) that proved to be the actual achromatic behavior of the phase shifter, despite its modest value. Extrapolated to mid-IR, its performance would be within typical specifications of a space mission as Darwin.

  7. High power phase shifter

    SciTech Connect

    Foster, B.; Gonin, I.; Khabiboulline, T.; Makarov, A.; Solyak, N.; Terechkine, I.; Wildman, D.; /Fermilab

    2005-05-01

    One of the approaches to power distribution system of a superconducting proton linac under discussion at FNAL requires development of a fast-action, megawatt-range phase shifter. Using a couple of this kind of devices with a waveguide hybrid junction can allow independent control of phase and amplitude of RF power at the input of each superconducting cavity, which will result in significant saving in number of klystrons and modulators required for the accelerator. A prototype of a waveguide version of the shifter that uses Yttrium-Iron Garnet (YIG) blocks was developed and tested. This report presents design concept of the device, and main results of simulation and proof-of-principle tests.

  8. Digitally controlled distributed phase shifter

    SciTech Connect

    Hietala, V.M.; Kravitz, S.H.; Vawter, G.A.

    1992-12-31

    A digitally controlled distributed phase shifter is comprised of N phase shifters. Digital control is achieved by using N binary length-weighted electrodes located on the top surface of a waveguide. A control terminal is attached to each electrode thereby allowing the application of a control signal. The control signal is either one of two discrete bias voltages. The application of the discrete bias voltages change the modal index of a portion of the waveguide that corresponds to a length of the electrode to which the bias voltage is applied, thereby causing the phase to change through the underlying portion of the waveguide. The digitally controlled distributed phase shift network has a total phase shift comprised of the sum of the individual phase shifters.

  9. Phase shifter for antenna beam steering

    NASA Astrophysics Data System (ADS)

    Jindal, Ravi; Razban, Tchanguiz

    2016-03-01

    Wide band Array Antenna operates in Ku-band (10.7-12.7 GHz) frequency composed of N×N radiating elements. This antenna aims at the reception of television satellite signals. The goal of this research is to provide better possibility of electronic beam control instead of manual or mechanical control, and design compact and low cost phase shifters to be inserted in the feeding network of this antenna. The electronic control of the phase shifter will allow the control of beam steering. The emphasis of this project will be done at the beginning on the design of a good phase shifter in Ku band. The aim of this research is to define, simulate, release and measure a continuous phase shifter. Better reflection loss, low transmission loss, low Cost of array antennas, large range of phase-shifter, phase flatness and bandwidth will be achieved by providing better gain.

  10. Light-driven phase shifter

    DOEpatents

    Early, James W.

    1990-01-01

    A light-driven phase shifter is provided for modulating a transmission light beam. A gaseous medium such as argon is provided with electron energy states excited to populate a metastable state. A tunable dye laser is selected with a wavelength effective to deplete the metastable electron state and may be intensity modulated. The dye laser is directed through the gaseous medium to define a first optical path having an index of refraction determined by the gaseous medium having a depleted metastable electron state. A transmission laser beam is also directed through the gaseous medium to define a second optical path at least partially coincident with the first optical path. The intensity of the dye laser beam may then be varied to phase modulate the transmission laser beam.

  11. Array Phase Shifters: Theory and Technology

    NASA Technical Reports Server (NTRS)

    Romanofsky, Robert R.

    2007-01-01

    While there are a myriad of applications for microwave phase shifters in instrumentation and metrology, power combining, amplifier linearization, and so on, the most prevalent use is in scanning phased-array antennas. And while this market continues to be dominated by military radar and tracking platforms, many commercial applications have emerged in the past decade or so. These new and potential applications span low-Earth-orbit (LEO) communications satellite constellations and collision warning radar, an aspect of the Intelligent Vehicle Highway System or Automated Highway System. In any case, the phase shifters represent a considerable portion of the overall antenna cost, with some estimates approaching 40 percent for receive arrays. Ferrite phase shifters continue to be the workhorse in military-phased arrays, and while there have been advances in thin film ferrite devices, the review of this device technology in the previous edition of this book is still highly relevant. This chapter will focus on three types of phase shifters that have matured in the past decade: GaAs MESFET monolithic microwave integrated circuit (MMIC), micro-electromechanical systems (MEMS), and thin film ferroelectric-based devices. A brief review of some novel devices including thin film ferrite phase shifters and superconducting switches for phase shifter applications will be provided. Finally, the effects of modulo 2 phase shift limitations, phase errors, and transient response on bit error rate degradation will be considered.

  12. Optically-controlled coplanar waveguide phase shifters

    NASA Astrophysics Data System (ADS)

    Neikirk, Dean P.; Cheung, Philip; Islam, M. Saiful; Itoh, Tatsuo

    1989-12-01

    This paper discusses the principles of optically-controlled phase shifters, with particular attention given to the design tradeoffs associated with optically-controlled coplanar waveguide (CPW) phase shifters. Experimental results from several different structures are presented. It is concluded that the coplanar waveguide transmission lines on semiconductor substrates, while structurally suited for optical control of the slow wave factor, might not be practical for MMIC applications, because they require very high optical illumination intensities to produce useful phase shifts. However, by combining a reverse-biased, Schottky barrier-contacted CPW with controlled optical illumination, large phase shifts at very low intensities can be achieved.

  13. Continuously variable voltage-controlled phase shifter

    NASA Technical Reports Server (NTRS)

    Johns, C. E.

    1970-01-01

    Phase shifter circuit adjusts the phase relationship between a locally generated reference frequency and a received RF signal applied to a phase-coherent detector. It is small enough to be integrated into a receiver subassembly and operates on command from remote control panels.

  14. A Model for Ferroelectric Phase Shifters

    NASA Technical Reports Server (NTRS)

    Romanofsky, Robert R.; Qureshi, A. Haq

    2000-01-01

    Novel microwave phase shifters consisting of coupled microstrip lines on thin ferroelectric films have been demonstrated recently. A theoretical model useful for predicting the propagation characteristics (insertion phase shift, dielectric loss, impedance, and bandwidth) is presented here. The model is based on a variational solution for line capacitance and coupled strip transmission line theory.

  15. shifter

    SciTech Connect

    Jacobsen, Douglas

    2015-06-01

    Shifter enables application virtualization or containerization in large-scale HPC environments. This technology decreases the effort to port applications to or between HPC sites while increasing reproducibility and scientific productivity. Shifter works by converting application/container images to a common format, and then leverages basic Linux functionality to make that image available to batch jobs run in the HPC environment.

  16. Enhancing FEL Power with Phase Shifters

    SciTech Connect

    Ratner, Daniel; Chao, Alex; Huang, Zhirong; /SLAC

    2010-07-30

    Tapering the undulator parameter is a well-known method for maintaining the resonant condition past saturation, and increasing Free Electron Laser (FEL) efficiency. In this paper, we demonstrate that shifting the electron bunch phase relative to the radiation is equivalent to tapering the undulator parameter. Using discrete phase changes derived from optimized undulator tapers for the Linac Coherent Light Source (LCLS) x-ray FEL, we show that appropriate phase shifts between undulator sections can reproduce the power enhancement of undulator tapers. Phase shifters are relatively easy to implement and operate, and could be used to aid or replace undulator tapers in optimizing FEL performance.

  17. Study of Liquid Phase Shifter for ICRF on EAST

    NASA Astrophysics Data System (ADS)

    Wang, Peng; Zhao, Yanping; Mao, Yuzhou; Qin, Chengming

    2006-07-01

    A method of current drive with Ion Cyclotron Range of Frequency (ICRF) on Experimental Advanced Superconducting Tokomak (EAST) is described. A variety of liquid silicon oil heights in the phase shifter will bring the phase difference to the current drive. It is found that the current drive can be achieved by using the phase shifter. The liquid phase shifter is one of the impedance matching systems too.

  18. A magnetoelectric composite based microwave phase shifter

    NASA Astrophysics Data System (ADS)

    Bichurin, M. I.; Petrov, V. M.; Srinivasan, G.

    2008-03-01

    Magnetoelectric (ME) properties of ferrite-ferroelectric composites arise from their response to elastic and electromagnetic force fields. The unique combination of magnetic, electrical, and ME interactions opens up the possibility of electric field tunable ferromagnetic resonance (FMR) based devices [1]. Here we discuss an ME phase shifter operating in the FMR region at 9.3 GHz. A slot line on a yttrium iron garnet film bonded to lead zirconate titanate (PZT) provides a basis for the phase shifter. The circularly polarized microwave magnetic field of the slot line interacts with the ferrite and causes variation of phase velocity with the controlling magnetic and electric fields. Electrical tuning is realized with the application of a control voltage due to PZT. The estimated phase shift per unit length and unit voltage is to 20 deg/cm kV for a PZT thickness of 0.5 mm. 1 S. Shastry and G. Srinivasan, M.I. Bichurin, V.M. Petrov, A.S. Tatarenko. Phys. Rev. B, 70 064416 (2004). - supported by grants from the Office of Naval Research and the Russian Foundation for Basic Research.

  19. Nonlinear multiferroic phase shifters for microwave frequencies

    SciTech Connect

    Ustinov, Alexey B.; Kalinikos, Boris A.; Srinivasan, G.

    2014-02-03

    A nonlinear microwave phase shifter based on a planar multiferroic composite has been studied. The multiferroic structure is fabricated in the form of a bilayer consisting of yttrium iron garnet and barium strontium titanate. The principle of operation of the device is based on the linear and nonlinear control of the phase shift of the hybrid spin-electromagnetic waves propagating in the bilayer. The linear control is realized with magnetic and electric fields. The nonlinear control is provided by the input power of microwave signal. The device showed a nonlinear phase shift up to 250°, electric field induced phase shift up to 330°, and magnetic field induced phase shift of more than 180°.

  20. Phase shifter technology assessment - Prospects and applications

    NASA Technical Reports Server (NTRS)

    Sokolov, Vladimir

    1991-01-01

    Capabilities and limitations of MMIC phase shifter technology at microwave and millimeter wave frequencies are reviewed. MMIC-based phase arrays make it possible to integrate active elements at the array face, i.e., to incorporate transmit power amplifiers and/or low noise amplifiers at each antenna element. Active elements make it possible to increase power efficiency and reliability and provide graceful degradation. Monolithic integration of the various transmit/receive functions including phase shifting is considered to be feasible through at least the lower millimeter-wave frequency range (about 30-100 GHz). MMIC integration also allows more flexibility in array design including those that are intended for airborne conformal applications.

  1. Liquid crystal phase shifters for space applications

    NASA Astrophysics Data System (ADS)

    Woehrle, Christopher D.

    Space communication satellites have historically relied heavily on high gain gimbal dish antennas for performing communications. Reflector dish antennas lack flexibility in anti-jamming capabilities, and they tend to have a high risk associated to them given the need for mechanical mechanisms to beam steer. In recent years, a great amount of investment has been made into phased array antenna technologies. Phased arrays offer increased signal flexibility at reduced financial cost and in system risk. The problem with traditional phased arrays is the significant program cost and overall complexity added to the satellite by integrating antenna elements that require many dedicated components to properly perform adaptive beam steering. Several unique methods have been proposed to address the issues that plague traditional phase shifters slated for space applications. Proposed approaches range from complex mechanical switches (MEMS) and ferroelectric devices to more robust molecular changes. Nematic liquid crystals offer adaptive beam steering capabilities that traditional phased arrays have; however, with the added benefit of reduced system cost, complexity, and increased resilience to space environmental factors. The objective of the work presented is to investigate the feasibility of using nematic liquid crystals as a means of phase shifting individual phased array elements slated for space applications. Significant attention is paid to the survivability and performance of liquid crystal and associated materials in the space environment. Performance regarding thermal extremes and interactions with charged particles are the primary factors addressed.

  2. Soliton-guided phase shifter and beam splitter

    SciTech Connect

    Steiglitz, Ken

    2010-03-15

    We propose, analyze, and study numerically a phase shifter for light wave packets trapped by Kerr solitons in a nonlinear medium. We also study numerically a previously proposed soliton-guided nonpolarizing beam splitter.

  3. Phase shifters. Citations from the NTIS data base

    NASA Astrophysics Data System (ADS)

    Reed, W. E.

    1980-05-01

    The bibliography cites Federally-funded research on the design, performance, and utilization of phase shifters and phase shift circuits. The types include ferrite, semiconductor, digital, and voltage controlled. Applications cover phased arrays, microwave equipment, surface acoustic wave devices, strip transmission lines, phases shift keyers, signal processors, and control equipment. This updated bibliography contains 20 abstracts.

  4. Analysis and Optimization of Thin Film Ferroelectric Phase Shifters

    NASA Technical Reports Server (NTRS)

    Romanofsky, Robert R.; VanKeuls, Fred W.; Warner, Joseph D.; Mueller, Carl H.; Alterovitz, Samuel A.; Miranda, Felix A.; Qureshi, A. Haq; Romanofsky, Robert R. (Technical Monitor)

    2000-01-01

    Microwave phase shifters have been fabricated from (YBa2Cu3O(7-delta) or Au)/SrTiO3 and Au/Ba(x)Sr(1-x)TiO3 films on LaAlO3 and MgO substrates. These coupled microstrip devices rival the performance of their semiconductor counter-parts parts at Ku- and K-band frequencies. Typical insertion loss for room temperature ferroelectric phase shifters at K-band is approximately equal 5 dB. An experimental and theoretical investigation of these novel devices explains the role of the ferroelectric film in overall device performance. A roadmap to the development of a 3 dB insertion loss phase shifter that would enable a new type of phased array antenna is discussed.

  5. High power l-band fast phase shifter

    SciTech Connect

    Terechkine, I.; Khabiboulline, T.; Solyak, N.; /Fermilab

    2008-10-01

    Following successful testing of a concept prototype of a waveguide-based high power phase shifter, a design of a fast, high power device has been developed. The shifter uses two magnetically biased blocks of Yttrium Iron Garnet (YIG) positioned along the side walls of a rectangular waveguide. The cross-section of the waveguide is chosen to suppress unwanted RF modes that could otherwise compromise performance of the phase shifter. Static bias field in the YIG blocks is created by employing permanent magnets. Low inductance coils in the same magnetic circuit excite fast component of the bias field. Design of the device ensures effective heat extraction from the YIG blocks and penetration of the fast magnetic field inside the waveguide with minimum delay. This paper summarizes main steps in this development and gives brief description of the system.

  6. Interference Confocal Microscope Integrated with Spatial Phase Shifter

    PubMed Central

    Wang, Weibo; Gu, Kang; You, Xiaoyu; Tan, Jiubin; Liu, Jian

    2016-01-01

    We present an interference confocal microscope (ICM) with a new single-body four-step simultaneous phase-shifter device designed to obtain high immunity to vibration. The proposed ICM combines the respective advantages of simultaneous phase shifting interferometry and bipolar differential confocal microscopy to obtain high axis resolution, large dynamic range, and reduce the sensitivity to vibration and reflectance disturbance seamlessly. A compact single body spatial phase shifter is added to capture four phase-shifted interference signals simultaneously without time delay and construct a stable and space-saving simplified interference confocal microscope system. The test result can be obtained by combining the interference phase response and the bipolar property of differential confocal microscopy without phase unwrapping. Experiments prove that the proposed microscope is capable of providing stable measurements with 1 nm of axial depth resolution for either low- or high-numerical aperture objective lenses. PMID:27563909

  7. Interference Confocal Microscope Integrated with Spatial Phase Shifter.

    PubMed

    Wang, Weibo; Gu, Kang; You, Xiaoyu; Tan, Jiubin; Liu, Jian

    2016-08-24

    We present an interference confocal microscope (ICM) with a new single-body four-step simultaneous phase-shifter device designed to obtain high immunity to vibration. The proposed ICM combines the respective advantages of simultaneous phase shifting interferometry and bipolar differential confocal microscopy to obtain high axis resolution, large dynamic range, and reduce the sensitivity to vibration and reflectance disturbance seamlessly. A compact single body spatial phase shifter is added to capture four phase-shifted interference signals simultaneously without time delay and construct a stable and space-saving simplified interference confocal microscope system. The test result can be obtained by combining the interference phase response and the bipolar property of differential confocal microscopy without phase unwrapping. Experiments prove that the proposed microscope is capable of providing stable measurements with 1 nm of axial depth resolution for either low- or high-numerical aperture objective lenses.

  8. Interference Confocal Microscope Integrated with Spatial Phase Shifter.

    PubMed

    Wang, Weibo; Gu, Kang; You, Xiaoyu; Tan, Jiubin; Liu, Jian

    2016-01-01

    We present an interference confocal microscope (ICM) with a new single-body four-step simultaneous phase-shifter device designed to obtain high immunity to vibration. The proposed ICM combines the respective advantages of simultaneous phase shifting interferometry and bipolar differential confocal microscopy to obtain high axis resolution, large dynamic range, and reduce the sensitivity to vibration and reflectance disturbance seamlessly. A compact single body spatial phase shifter is added to capture four phase-shifted interference signals simultaneously without time delay and construct a stable and space-saving simplified interference confocal microscope system. The test result can be obtained by combining the interference phase response and the bipolar property of differential confocal microscopy without phase unwrapping. Experiments prove that the proposed microscope is capable of providing stable measurements with 1 nm of axial depth resolution for either low- or high-numerical aperture objective lenses. PMID:27563909

  9. Novel monolithic phase shifter combining ferroelectrics and high temperature superconductors

    NASA Astrophysics Data System (ADS)

    Jackson, Charles M.; Kobayashi, June H.; Lee, Alfred; Pettiette-Hall, Claire; Burch, John F.; Hu, Roger; Hilton, Rick; McDade, Jim

    1992-12-01

    A novel phase shifter that combines the dielectric properties of a ferroelectric material SrTiO3 and the low loss of high-temperature superconductor (HTS) films is presented. Results show that the maximum phase shift of 8 percent was obtained at 29 K and greater phase shifts are possible with higher voltage bias values. Particular attention is given to the compatability of YBa2Cu3O7-x and a broad class of ferroelectric materials.

  10. Innovative phase shifter for pulse tube operating below 10 K

    NASA Astrophysics Data System (ADS)

    Duval, Jean-Marc; Charles, Ivan; Daniel, Christophe; André, Jérôme

    2016-09-01

    Stirling type pulse tubes are classically based on the use of an inertance phase shifter to optimize their cooling power. The limitations of the phase shifting capabilities of these inertances have been pointed out in various studies. These limitations are particularly critical for low temperature operation, typically below about 50 K. An innovative phase shifter using an inertance tube filled with liquid, or fluid with high density or low viscosity, and separated by a sealed metallic diaphragm has been conceived and tested. This device has been characterized and validated on a dedicated test bench. Operation on a 50-80 K pulse tube cooler and on a low temperature (below 8 K) pulse tube cooler have been demonstrated and have validated the device in operation. These developments open the door for efficient and compact low temperature Stirling type pulse tube coolers. The possibility of long life operation has been experimentally verified and a design for space applications is proposed.

  11. Investigation of an electronically tuned 100 GHz superconducting phase shifter

    SciTech Connect

    Tvack, E.K.; Shen, Z.Y.; Dang, H.; Radparvar, M.; Faris, S.M. )

    1991-03-01

    This paper presents the results of an investigation aimed at realizing a tunable superconducting mm-wave phase shifter. The tuning mechanism is based on inductance modulation of NbN microstrips by excess quasiparticle injection. When measured by a dc method, using the interference patterns and resonances of specially designed dc SQUIDs, the inductance of NbN microstrips can be varied by up to 300%. Based on these results, we have designed and fabricated superconducting microstrip interferometers to operate as low power 100 GHz phase shifters. The 100 GHZ signal is coupled into and out of the interferometers by finline antennas. Amplitude modulation of the output is used as the criterion for phase shift in one of the interferometer branches.

  12. Achromatic phase shifts utilizing dielectric plates for nulling interferometery

    NASA Astrophysics Data System (ADS)

    Morgan, R. M.; Burge, J. M.

    1998-12-01

    Schemes for detecting planets around other stars using interferometery have been developed which rely on a half wave phase delay to shift the central constructive fringe of an interferometer to a deep, destructive null fringe. To achieve the sensitivity and spectroscopy desired for exo-planets observations, such a null must be achromatic over a broad spectral region. One method for creating such a half wave phase delay achromatically involves the use of pairs of dielectric, plane parallel plates, analogous to the use of two types of glass in an achromatic lens. An analysis of the technique is presented with solutions using single plates to achieve null fringes to a cancellation of 10 exp -4 in the visible, near infrared, and mid infrared for null. Solutions using two matched materials show that nulls to a depth of 10 exp -6 are achievable in 2 um bands in the 7-17 um regime, or to a depth of 10 exp -5 over the entire 7-17 um band. Experimental results using a single plate of BK7 in the visible spectrum verify the technique.

  13. Digital phase shifter synchronizes local oscillators

    NASA Technical Reports Server (NTRS)

    Ali, S. M.

    1978-01-01

    Digital phase-shifting network is used as synchronous frequency multiplier for applications such as phase-locking two signals that may differ in frequency. Circuit has various phase-shift capability. Possible applications include data-communication systems and hybrid digital/analog phase-locked loops.

  14. Achromatic phase matching at third orders of dispersion

    DOEpatents

    Richman, Bruce

    2003-10-21

    Achromatic phase-matching (APM) is used for efficiently multiplying the frequency of broad bandwidth light by using a nonlinear optical medium comprising a second-harmonic generation (SHG) crystal and stationary optical elements whose configuration, properties, and arrangement have been optimized to match the angular dispersion characteristics of the SHG crystal to at least the third order. These elements include prisms and diffraction gratings for directing an input light beam onto the SHG crystal such that each ray wavelength is aligned to match the phase-matching angle for the crystal at each wavelength of light to at least the third order and such that every ray wavelength overlap within the crystal.

  15. RF MEMS Phase Shifters and their Application in Phase Array Antennas

    NASA Technical Reports Server (NTRS)

    Scardelletti, Maximilian; Ponchak, George E.; Zaman, Afroz J.; Lee, Richard Q.

    2005-01-01

    Electronically scanned arrays are required for space based radars that are capable of tracking multiple robots, rovers, or other assets simultaneously and for beam-hopping communication systems between the various assets. ^Traditionally, these phased array antennas used GaAs Monolithic Microwave Integrated Circuit (MMIC) phase shifters, power amplifiers, and low noise amplifiers to amplify and steer the beam, but the development of RF MEMS switches over the past ten years has enabled system designers to consider replacing the GaAs MMIC phase shifters with RF Micro-Electro Mechanical System (MEMS) phase shifters. In this paper, the implication of replacing the relatively high loss GaAs MMICs with low loss MEMS phase shifters is investigated.

  16. Silicon-based phase shifters for high figure of merit in optical modulation

    NASA Astrophysics Data System (ADS)

    Ogawa, Kensuke; Goi, Kazuhiro; Ishikura, Norihiro; Ishihara, Hiroki; Sakamoto, Shinichi; Liow, Tsung-Yang; Tu, Xiaoguang; Lo, Guo-Qiang; Kwong, Dim-Lee; Lim, Soon Thor; Sun, Min Jie; Png, Ching Eng

    2016-03-01

    This paper focuses on latest progress in experimental and theoretical studies on silicon-based carrier-depletion PNjunction phase shifters in terms of high modulation efficiency for energy-efficient photonic networks of high transmission capacity. Modulation efficiency of rib-waveguide phase shifters having various PN-junction configuration are characterized with respect to DC figure of merit defined for phase shifters using carrier-plasma dispersion as the physical principle of refractive-index modulation. In addition, RF drive voltage required for 10-Gb/s on-off keying is characterized for rib-waveguide phase shifters including lateral and vertical PN-junction configurations.

  17. A compact frequency tunable radio frequency phase shifter with patterned Py enabled transmission line

    SciTech Connect

    Rahman, B.M. Farid; Divan, Ralu; Rosenmann, Daniel; Wang, Tengxing; Peng, Yujia; Wang, Guoan

    2015-01-01

    A well designed frequency tunable phase shifter using patterned Py with different thickness has been demonstrated. Phase shifter is implemented with a slow wave coplanar wave guide (CPW)transmission line, where the signal line has alternate short narrow and wide sections. Py is patterned on the top of narrow section for high inductance density, and inter-digital capacitor is implemented in wide section for high capacitance density. Compared with phase shifter using regular CPW, the dimension of the developed phase shifter has been reduced from 14.86 mm to4.70 mm at 2 GHz. Phase shifter based on 100 nm and 200 nm thick patterned Py with the same dimensions (14lm10lm) are implemented and investigated comprehensively. FMR frequency of 3.2 GHz and 3.6 GHz without any external magnetic field has been achieved for100 nm and 200 nm thick Py film, respectively. Thicker Py has increased inductance density from 1067.2 nH/m to 1193.2 nH/m while the center frequency of the phase shifter has been shifted to 1.80 GHz. Frequency tunability of the phase shifter has been also demonstrated withDC current. The phase shifter can provide 90phase shift continuously from 2 GHz to 1.80 GHz with DC current from 0 mA to 150 mA. The design concept has great potential in design arbitrary tunable RF components such as filters and couplers.

  18. Magnonic crystals-based tunable microwave phase shifters

    SciTech Connect

    Zhu, Y.; Chi, K. H.; Tsai, C. S.

    2014-07-14

    Tunable microwave phase shifters using magnetostatic backward volume waves in yttrium iron garnet/gadolinium gallium garnet thin film-based one-dimensional (1-D) and two-dimensional (2-D) magnonic crystals (MCs) are reported in this paper. Large differential phase shifts with small insertion loss variations were achieved in the passbands neighboring the bandgaps by tuning of the bias magnetic field. Large phase tuning rates up to 13.48 °/(Oe cm) and 25.9 °/(Oe cm) together with small insertion loss variations of 2.08 dB/cm and 0.97 dB/cm were demonstrated in the 1-D and 2-D MCs, respectively. An excellent agreement between the measured and the calculated results based on Walker's equation was obtained.

  19. Superconducting Coplanar Switch and Phase Shifter for CMB Applications

    NASA Astrophysics Data System (ADS)

    Bordier, G.; Cammilleri, V. D.; Belier, B.; Bleurvacq, N.; Gadot, F.; Ghribi, A.; Piat, M.; Tartari, A.; Zanonni, M.

    2016-08-01

    The next generations of cosmic microwave background (CMB) instruments will be dedicated to the detection and characterization of CMB B-modes. To measure this tiny signal, instruments need to control and minimize systematics. Signal modulation is one way to achieve such a control. A new generation of focal planes will include the entire detection chain. In this context, we present a superconducting coplanar switch driven by DC current. It consists of a superconducting microbridge which commutes between its on (superconducting) and off (normal metal) states, depending on the amplitude of the injected current compared to the critical current. If the current injected inside the bridge is lower than the critical current, the phase of the signal passing through the bridge is tunable. A first prototype of this component working as a switch and as a phase shifter at 10 GHz has been made. The principle, the setup, and the first measurements made at 4 K will be shown.

  20. Ka-Band, MEMS Switched Line Phase Shifters Implemented in Finite Ground Coplanar Waveguide

    NASA Technical Reports Server (NTRS)

    Scardelletti, Maximilian C.; Ponchak, George E.; Varaljay, Nicholas C.

    2005-01-01

    Ka-band MEMS switched line phase shifters implemented in finite ground coplanar waveguide are described in this paper. The phase shifters are constructed of single-pole double-throw (SPDT) switches with additional reference and phase offset transmission line lengths. The one- and two-bit phase shifters are fabricated on high resistivity (HR) silicon with a dielectric constant, Epsilon(sub T) = 11.7 and a substrate thickness, t = 500microns. The switching architectures integrated within the phase shifters consist of MEMS switches that are doubly anchored cantilever beam capacitive switches with additional high inductive sections (MEMS LC device). The SPDT switch is composed of a T-junction with a MEMS LC device at each output port. The one-bit phase shifter described in this paper has an insertion loss (IL) and return loss (RL) of 0.9 dB and 30 dB while the two-bit described has an IL and RL of 1.8 dB and 30 dB respectively. The one-bit phase shifter's designed offset phase is 22.5deg and actual measured phase shift is 21.8deg. The two-bit phase shifter's designed offset phase is 22.5deg, 45deg, and 67.5deg and the actual measured phase shifts are 21.4deg, 44.2deg, and 65.8deg, respectively.

  1. Q-band 4-state phase shifter in planar technology: Circuit design and performance analysis

    NASA Astrophysics Data System (ADS)

    Villa, E.; Cagigas, J.; Aja, B.; de la Fuente, L.; Artal, E.

    2016-09-01

    A 30% bandwidth phase shifter with four phase states is designed to be integrated in a radio astronomy receiver. The circuit has two 90° out-of-phase microwave phase-shifting branches which are combined by Wilkinson power dividers. Each branch is composed of a 180° phase shifter and a band-pass filter. The 180° phase shifter is made of cascaded hybrid rings with microwave PIN diodes as switching devices. The 90° phase shift is achieved with the two band-pass filters. Experimental characterization has shown significant results, with average phase shift values of -90.7°, -181.7°, and 88.5° within the operation band, 35-47 GHz, and mean insertion loss of 7.4 dB. The performance of its integration in a polarimetric receiver for radio astronomy is analyzed, which validates the use of the presented phase shifter in such type of receiver.

  2. Constant volume gas cell optical phase-shifter

    DOEpatents

    Phillion, Donald W.

    2002-01-01

    A constant volume gas cell optical phase-shifter, particularly applicable for phase-shifting interferometry, contains a sealed volume of atmospheric gas at a pressure somewhat different than atmospheric. An optical window is present at each end of the cell, and as the length of the cell is changed, the optical path length of a laser beam traversing the cell changes. The cell comprises movable coaxial tubes with seals and a volume equalizing opening. Because the cell is constant volume, the pressure, temperature, and density of the contained gas do not change as the cell changes length. This produces an exactly linear relationship between the change in the length of the gas cell and the change in optical phase of the laser beam traversing it. Because the refractive index difference between the gas inside and the atmosphere outside is very much the same, a large motion must be made to change the optical phase by the small fraction of a wavelength that is required by phase-shifting interferometry for its phase step. This motion can be made to great fractional accuracy.

  3. Multispectral optical metasurfaces enabled by achromatic phase transition

    NASA Astrophysics Data System (ADS)

    Zhao, Zeyu; Pu, Mingbo; Gao, Hui; Jin, Jinjin; Li, Xiong; Ma, Xiaoliang; Wang, Yanqin; Gao, Ping; Luo, Xiangang

    2015-10-01

    The independent control of electromagnetic waves with different oscillating frequencies is critical in the modern electromagnetic techniques, such as wireless communications and multispectral imaging. To obtain complete control of different light waves with optical materials, the chromatic dispersion should be carefully controlled, which is however extremely difficult. In this paper, we propose a method to control the behaviors of different light waves through a metasurface which is able to generate achromatic geometric phase. Using this approach, a doughnut-shaped and a solid light spot were achieved at the same focal plane using two light sources with different wavelengths as used in the stimulation emission depletion (STED) microscope system. In order to reveal the full capacity of such method, tight focusing at multiple wavelengths is also represented, where the focal spots of different wavelengths are located at the same position. The results provided here may open a new door to the design of subminiature optical components and integrated optical system operating at multiple wavelengths.

  4. Multispectral optical metasurfaces enabled by achromatic phase transition

    PubMed Central

    Zhao, Zeyu; Pu, Mingbo; Gao, Hui; Jin, Jinjin; Li, Xiong; Ma, Xiaoliang; Wang, Yanqin; Gao, Ping; Luo, Xiangang

    2015-01-01

    The independent control of electromagnetic waves with different oscillating frequencies is critical in the modern electromagnetic techniques, such as wireless communications and multispectral imaging. To obtain complete control of different light waves with optical materials, the chromatic dispersion should be carefully controlled, which is however extremely difficult. In this paper, we propose a method to control the behaviors of different light waves through a metasurface which is able to generate achromatic geometric phase. Using this approach, a doughnut-shaped and a solid light spot were achieved at the same focal plane using two light sources with different wavelengths as used in the stimulation emission depletion (STED) microscope system. In order to reveal the full capacity of such method, tight focusing at multiple wavelengths is also represented, where the focal spots of different wavelengths are located at the same position. The results provided here may open a new door to the design of subminiature optical components and integrated optical system operating at multiple wavelengths. PMID:26503607

  5. Multispectral optical metasurfaces enabled by achromatic phase transition.

    PubMed

    Zhao, Zeyu; Pu, Mingbo; Gao, Hui; Jin, Jinjin; Li, Xiong; Ma, Xiaoliang; Wang, Yanqin; Gao, Ping; Luo, Xiangang

    2015-10-27

    The independent control of electromagnetic waves with different oscillating frequencies is critical in the modern electromagnetic techniques, such as wireless communications and multispectral imaging. To obtain complete control of different light waves with optical materials, the chromatic dispersion should be carefully controlled, which is however extremely difficult. In this paper, we propose a method to control the behaviors of different light waves through a metasurface which is able to generate achromatic geometric phase. Using this approach, a doughnut-shaped and a solid light spot were achieved at the same focal plane using two light sources with different wavelengths as used in the stimulation emission depletion (STED) microscope system. In order to reveal the full capacity of such method, tight focusing at multiple wavelengths is also represented, where the focal spots of different wavelengths are located at the same position. The results provided here may open a new door to the design of subminiature optical components and integrated optical system operating at multiple wavelengths.

  6. Advances in Scanning Reflectarray Antennas Based on Ferroelectric Thin Film Phase Shifters for Deep Space Communications

    NASA Technical Reports Server (NTRS)

    Romanofsky, Robert R.

    2007-01-01

    Though there are a few examples of scanning phased array antennas that have flown successfully in space, the quest for low-cost, high-efficiency, large aperture microwave phased arrays continues. Fixed and mobile applications that may be part of a heterogeneous exploration communication architecture will benefit from the agile (rapid) beam steering and graceful degradation afforded by phased array antennas. The reflectarray promises greater efficiency and economy compared to directly-radiating varieties. Implementing a practical scanning version has proven elusive. The ferroelectric reflectarray, under development and described herein, involves phase shifters based on coupled microstrip patterned on Ba(x)Sr(1-x)TiO3 films, that were laser ablated onto LaAlO3 substrates. These devices outperform their semiconductor counterparts from X- through and K-band frequencies. There are special issues associated with the implementation of a scanning reflectarray antenna, especially one realized with thin film ferroelectric phase shifters. This paper will discuss these issues which include: relevance of phase shifter loss; modulo 2(pi) effects and phase shifter transient effects on bit error rate; scattering from the ground plane; presentation of a novel hybrid ferroelectric-semiconductor phase shifter; and the effect of mild radiation exposure on phase shifter performance.

  7. Tunable ferroelectric meta-material phase shifter embedded inside low temperature co-fired ceramics (LTCC)

    NASA Astrophysics Data System (ADS)

    Tork, Hossam S.

    This dissertation describes electrically tunable microwave devices utilizing low temperature co-fired ceramics (LTCC) and thick film via filled with the ferroelectric materials barium strontium titanate (BST) and barium zirconate titanate (BZT). Tunable ferroelectric capacitors, zero meta-material phase shifters, and tunable meta-material phase shifters are presented. Microwave phase shifters have many applications in microwave devices. They are essential components for active and passive phased array antennas and their most common use is in scanning phased array antennas. They are used in synthetic aperture radars (SAR), low earth orbit (LEO) communication satellites, collision warning radars, and intelligent vehicle highway systems (IVHS), in addition to various other applications. Tunable ferroelectric materials have been investigated, since they offer the possibility of lowering the total cost of phased arrays. Two of the most promising ferroelectric materials in microwave applications are BST and BZT. The proposed design and implementation in this research introduce new types of tunable meta-material phase shifters embedded inside LTCC, which use BST and BZT as capacitive tunable dielectric material controlled by changing the applied voltage. This phase shifter has the advantages of meta-material structures, which produce little phase error and compensation while having the simultaneous advantage of using LTCC technology for embedding passive components that improve signal integrity (several signal lines, power planes, and ground planes) by using different processes like via filling, screen printing, laminating and firing that can be produced in compact sizes at a low cost. The via filling technique was used to build tunable BST, BZT ferroelectric material capacitors to control phase shift. Finally, The use of the proposed ferroelectric meta-material phase shifter improves phase shifter performance by reducing insertion loss in both transmitting and receiving

  8. The application of taylor weighting, digital phase shifters, and digital attenuators to phased-array antennas.

    SciTech Connect

    Brock, Billy C.

    2008-03-01

    Application of Taylor weighting (taper) to an antenna aperture can achieve low peak sidelobes, but combining the Taylor weighting with quantized attenuators and phase shifters at each radiating element will impact the performance of a phased-array antenna. An examination of array performance is undertaken from the simple point of view of the characteristics of the array factor. Design rules and guidelines for determining the Taylor-weighting parameters, the number of bits required for the digital phase shifter, and the dynamic range and number of bits required for the digital attenuator are developed. For a radar application, when each element is fed directly from a transmit/receive module, the total power radiated by the array will be reduced as a result of the taper. Consequently, the issue of whether to apply the taper on both transmit and receive configurations, or only on the receive configuration is examined with respect to two-way sidelobe performance.

  9. Differential phase contrast in scanning x-ray microscopy with half-wavelength phase shifter

    NASA Astrophysics Data System (ADS)

    Suzuki, Yoshio; Takeuchi, Akihisa

    2016-01-01

    A method for differential-phase-contrast imaging in scanning x-ray microscopy is proposed. The microfocus beam is produced with an x-ray focusing optics, and a half of the optical aperture is masked with a λ/2 phase shifter. This generates a pair of focused beam at the focal plane, with π phase difference. Combining with a diaphragm in front of the transmission beam detector, differential phase contrast (contrast proportional to the phase-difference between two foci) can be obtained. Preliminary results with a Fresnel zone plate focusing optics at 12.4 keV x-ray energy are shown.

  10. A compact, low-loss, tunable phase shifter on defect mitigated dielectrics up to 40 GHz

    NASA Astrophysics Data System (ADS)

    Orloff, Nathan; Long, Christian; Lu, Xifeng; Nair, Hari; Dawley, Natalie; Schlom, Darrell; Booth, James

    With the emergence of the internet-of-things and increased connectivity of modern commerce, consumers have driven demand for wireless spectrum beyond current capacity and infrastructure capabilities. One way the telecommunications industry is addressing this problem is by pushing front-end electronics to higher frequencies, introducing carrier aggregation schemes, and developing spectrum-sharing techniques. Some of these solutions require frequency agile components that are vastly different from what is in today's marketplace. Perhaps the most basic and ubiquitous component in front-end electronics is the phase shifter. Phase shifters are particularly important for compact beam-forming antennas that may soon appear in commercial technology. Here, we demonstrate a compact, tunable phase shifter with very low insertion loss up to 40 GHz on a defect mitigated tunable dielectric. We demonstrate performance compared to barium-doped strontium titanate phase shifters. Such phase shifters could potentially meet the stringent size and performance characteristics demanded by telecommunications industry, readily facilitating massive multiple-input multiple-output antennas in the next-generation of mobile handsets.

  11. Liquid crystal terahertz phase shifters with functional indium-tin-oxide nanostructures for biasing and alignment

    SciTech Connect

    Yang, Chan-Shan; Tang, Tsung-Ta; Pan, Ru-Pin; Yu, Peichen; Pan, Ci-Ling

    2014-04-07

    Indium Tin Oxide (ITO) nanowhiskers (NWhs) obliquely evaporated by electron-beam glancing-angle deposition can serve simultaneously as transparent electrodes and alignment layer for liquid crystal (LC) devices in the terahertz (THz) frequency range. To demonstrate, we constructed a THz LC phase shifter with ITO NWhs. Phase shift exceeding π/2 at 1.0 THz was achieved in a ∼517 μm-thick cell. The phase shifter exhibits high transmittance (∼78%). The driving voltage required for quarter-wave operation is as low as 5.66 V (rms), compatible with complementary metal-oxide-semiconductor (CMOS) and thin-film transistor (TFT) technologies.

  12. Bias-free spin-wave phase shifter for magnonic logic

    NASA Astrophysics Data System (ADS)

    Louis, Steven; Lisenkov, Ivan; Nikitov, Sergei; Tyberkevych, Vasyl; Slavin, Andrei

    2016-06-01

    A design of a magnonic phase shifter operating without an external bias magnetic field is proposed. The phase shifter uses a localized collective spin wave mode propagating along a domain wall "waveguide" in a dipolarly-coupled magnetic dot array with a chessboard antiferromagnetic (CAFM) ground state. It is demonstrated numerically that the remagnetization of a single magnetic dot adjacent to the domain wall waveguide introduces a controllable phase shift in the propagating spin wave mode without significant change to the mode amplitude. It is also demonstrated that a logic XOR gate can be realized in the same system.

  13. A wide range, high yield and good performance pHEMT switch for MMIC phase shifter

    NASA Astrophysics Data System (ADS)

    Menbari, Babak; Dousti, Massoud; Hajghassem, Hassan

    2014-11-01

    A low-cost method with high yield and good performance is presented by pHEMTs (pseudomorphic high electron mobility transistors) to be used in phase shifter switches. In this method, the capacitor in "off" mode (Coff) of transistor is reduced, without variation of the transistor structure. The transistor structure in switch mode can be optimised. This method increases the transistor isolation in turn "off" mode, while there is no change in resistance of the transistor in "on" mode (Ron). Transistor dimension is determined in turn "off" mode (Vg = -4.5 V) and standard form of 4 × 75 μm. So, in this method, insertion loss will be reduced without a perceptible change in transistor dimension. Thus, design and fabrication capability of some circuits such as phase shifters, antenna switches, SPDT (single port double throw) - without any change in technology - are increasing. In this paper, post layout and measurement result for a sample block of phase shifter are shown.

  14. A Theoretical Model for Thin Film Ferroelectric Coupled Microstripline Phase Shifters

    NASA Technical Reports Server (NTRS)

    Romanofsky, R. R.; Quereshi, A. H.

    2000-01-01

    Novel microwave phase shifters consisting of coupled microstriplines on thin ferroelectric films have been demonstrated recently. A theoretical model useful for predicting the propagation characteristics (insertion phase shift, dielectric loss, impedance, and bandwidth) is presented here. The model is based on a variational solution for line capacitance and coupled strip transmission line theory.

  15. Sub-15fs ultraviolet pulses generated by achromatic phase-matching sum-frequency mixing.

    PubMed

    Zhao, Baozhen; Jiang, Yongliang; Sueda, Keiich; Miyanaga, Noriaki; Kobayashi, Takayoshi

    2009-09-28

    A broadband ultraviolet pulse with a spectral width of 44 nm was generated by achromatic sum-frequency mixing of an 805-nm pulse and ultrabroadband visible pulse. Angular dispersion was introduced to achieve broadband phase matching by a prism pair. The UV pulse was compressed to 13.2 fs with another prism pair, with energy of 600 nJ. PMID:19907556

  16. A tunable millimeter-wave phase shifter driven by dielectric elastomer actuators

    NASA Astrophysics Data System (ADS)

    Araromi, O. A.; Romano, P.; Rosset, S.; Perruisseau-Carrier, J.; Shea, H. R.

    2014-03-01

    We present the successful operation of the first dielectric elastomer actuator (DEA) driven tunable millimeter-wave phase shifter. The development of dynamically reconfigurable microwave/millimeter-wave (MW/MMW) antenna devices is becoming a prime need in the field of telecommunications and sensing. The real time updating of antenna characteristics such as coverage or operation frequency is particularly desired. However, in many circumstances currently available technologies suffer from high EM losses, increased complexity and cost. Conversely, reconfigurable devices based on DEAs offer low complexity, low electromagnetic (EM) losses and analogue operation. Our tunable phase shifter consists of metallic strips suspended a fixed distance above a coplanar waveguide (CPW) by planar DEAs. The planar actuators displace the metallic strips (10 mm in length) in-plane by 500 μm, modifying the EM field distribution, resulting in the desired phase shift. The demanding spacing (50 +/-5 μm between CPW and metallic strips) and parallel alignment criteria required for optimal device operation are successfully met in our device design and validated using bespoke methods. Our current device, approximately 60 mm x 60 mm in planar dimensions, meets the displacement requirements and we observe a considerable phase shift (~95° at 25 GHz) closely matching numerical simulations. Moreover, our device achieves state of the art performance in terms of phase shift per EM loss ~235°/dB (35 GHz), significantly out performing other phase shifter technologies, such as MMIC phase shifters.

  17. Novel Phased Array Scanning Employing A Single Feed Without Using Individual Phase Shifters

    NASA Technical Reports Server (NTRS)

    Host, Nicholas K.; Chen, Chi-Chih; Volakis, John L.; Miranda, Felix A.

    2012-01-01

    Phased arrays afford many advantages over mechanically steered systems. However, they are also more complex, heavy, and most of all costly. The high cost mainly originates from the complex feeding structure. This paper proposes a novel feeding scheme to eliminate all phase shifters and achieve scanning via one-dimensional motion. Beam scanning is achieved via a series fed array incorporating feeding transmission lines whose wave velocity can be mechanically adjusted. Along with the line design, ideal element impedances to be used in conjunction with the line are derived. Practical designs are shown which achieve scanning to +/-30deg from boresight. Finally, a prototype is fabricated and measured, demonstrating the concept.

  18. A Ku band 5 bit MEMS phase shifter for active electronically steerable phased array applications

    NASA Astrophysics Data System (ADS)

    Sharma, Anesh K.; Gautam, Ashu K.; Farinelli, Paola; Dutta, Asudeb; Singh, S. G.

    2015-03-01

    The design, fabrication and measurement of a 5 bit Ku band MEMS phase shifter in different configurations, i.e. a coplanar waveguide and microstrip, are presented in this work. The development architecture is based on the hybrid approach of switched and loaded line topologies. All the switches are monolithically manufactured on a 200 µm high resistivity silicon substrate using 4 inch diameter wafers. The first three bits (180°, 90° and 45°) are realized using switched microstrip lines and series ohmic MEMS switches whereas the fourth and fifth bits (22.5° and 11.25°) consist of microstrip line sections loaded by shunt ohmic MEMS devices. Individual bits are fabricated and evaluated for performance and the monolithic device is a 5 bit Ku band (16-18 GHz) phase shifter with very low average insertion loss of the order of 3.3 dB and a return loss better than 15 dB over the 32 states with a chip area of 44 mm2. A total phase shift of 348.75° with phase accuracy within 3° is achieved over all of the states. The performance of individual bits has been optimized in order to achieve an integrated performance so that they can be implemented into active electronically steerable antennas for phased array applications.

  19. Approaches for Achieving Broadband Achromatic Phase Shifts for Visible Nulling Coronagraphy

    NASA Technical Reports Server (NTRS)

    Bolcar, Matthew R.; Lyon, Richard G.

    2012-01-01

    Visible nulling coronagraphy is one of the few approaches to the direct detection and characterization of Jovian and Terrestrial exoplanets that works with segmented aperture telescopes. Jovian and Terrestrial planets require at least 10(exp -9) and 10(exp -10) image plane contrasts, respectively, within the spectral bandpass and thus require a nearly achromatic pi-phase difference between the arms of the interferometer. An achromatic pi-phase shift can be achieved by several techniques, including sequential angled thick glass plates of varying dispersive materials, distributed thin-film multilayer coatings, and techniques that leverage the polarization-dependent phase shift of total-internal reflections. Herein we describe two such techniques: sequential thick glass plates and Fresnel rhomb prisms. A viable technique must achieve the achromatic phase shift while simultaneously minimizing the intensity difference, chromatic beam spread and polarization variation between each arm. In this paper we describe the above techniques and report on efforts to design, model, fabricate, align the trades associated with each technique that will lead to an implementations of the most promising one in Goddard's Visible Nulling Coronagraph (VNC).

  20. Large Microwave Birefringence Liquid-Crystal Characterization for Phase-Shifter Applications

    NASA Astrophysics Data System (ADS)

    Dubois, Frédéric; Krasinski, Freddy; Splingart, Bertrand; Tentillier, Nicolas; Legrand, Christian; Spadlo, Anna; Dabrowski, Roman

    2008-05-01

    This work is concerned with the improvement of a microwave liquid-crystal phase shifter using a large birefringence nematic liquid crystal. This material is a eutectic mixture of isothiocyanatotolane molecules. Microwave dielectric properties are reported and compared to the data obtained with the 5CB cyanobiphenyl material in the 26-40 GHz frequency range using a rectangular waveguide. The phase-shifter design consists of a central cavity, where a liquid crystal is inserted, and two coplanar strip lines accesses. Its dimensions were calculated by electromagnetic simulation, using measured dielectric permittivities of the liquid crystal. The measurements were performed with a commercial Wiltron 3680 K probe test fixture. Phase-shift variations with and without bias voltage versus frequency are presented. As expected, the large-birefringence nematic liquid crystal exhibits a higher microwave dielectric anisotropy (Δɛ' = 1.06 against 0.34) and the tunability of the phase shifter strongly increases (1.8 deg·cm-1·GHz-1 against 0.8 deg·cm-1·GHz-1).

  1. Comparative study of bolometric and non-bolometric switching elements for microwave phase shifters

    NASA Technical Reports Server (NTRS)

    Tabib-Azar, Massood; Bhasin, Kul B.; Romanofsky, Robert R.

    1991-01-01

    The performance of semiconductor and high critical temperature superconductor switches is compared as they are used in delay-line-type microwave and millimeter-wave phase shifters. Such factors as their ratios of the off-to-on resistances, parasitic reactances, power consumption, speed, input-to-output isolation, ease of fabrication, and physical dimensions are compared. Owing to their almost infinite off-to-on resistance ratio and excellent input-to-output isolation, bolometric superconducting switches appear to be quite suitable for use in microwave phase shifters; their only drawbacks are their speed and size. The SUPERFET, a novel device whose operation is based on the electric field effect in high critical temperature ceramic superconductors is also discussed. Preliminary results indicate that the SUPERFET is fast and that it can be scaled; therefore, it can be fabricated with dimensions comparable to semiconductor field-effect transistors.

  2. Interplay Between Thin Film Ferroelectric Composition, Microstructure and Microwave Phase Shifter Performance

    NASA Technical Reports Server (NTRS)

    Mueller, Carl H.; VanKeuls, Frederick W.; Romanofsky, Robert R.; Alterovitz, Samuel A.; Miranda, Felix A.

    2003-01-01

    One of the keys to successfully incorporating ferroelectric films into Ku-band (12 to 18 GHz) phase shifters is to establish the composition, microstructure, and thickness required to meet the tuning needs, and tailor the film properties to meet these needs. Optimal performance is obtained when the film composition and device design are such that the device performance is limited by odd mode dielectric losses, and these losses are minimized as much as possible while still maintaining adequate tunability. The parameters required to maintain device performance will vary slightly depending on composition, but we can conclude that the best tuning-to-loss figures of merit (K-factor) are obtained when there is minimal variation between the in-plane and out-of-plane lattice parameters, and the full-width half maximum values of the BSTO (002) peaks are less than approximately 0.04 deg. We have observed that for phase shifters in which the ferroelectric crystalline quality and thickness are almost identical, higher losses are observed in films with higher BaISr ratios. The best performance was observed in phase shifters with Ba:Sr = 30:70. The superiority of this composition was attributed to several interacting factors: the B a: Sr ratio was such that the Curie temperature (180 K) was far removed from room temperature, the crystalline quality of the film was excellent, and there was virtually no difference between the inplane and out-of-plane lattice parameters of the film.

  3. Ferrite phase shifters using stress insensitive materials. Final report, July 1991-July 1993

    SciTech Connect

    Vaughn, T.; Cox, P.; Harrison, G.; Rodrigue, P.

    1993-10-01

    This RD program sponsored by the Naval Research Laboratory and being conducted by EMS Technologies, Inc., Norcross, Georgia, is focused toward achieving improved performance in microwave switching components via use of stress insensitive' microwave ferrite materials for applications where stable hysteresis characteristics of the materials are critical to the RF performance. The program, therefore, primarily addresses how to relieve or improve the magnetostrictive characteristics of the materials with emphasis on the specific application and demonstration of these materials in microwave switching components, particularly ferrite toroidal phase shifters. Material investigations were focused on Mn+3 substitutions in Yttrium-gadolinium iron garnet. These compounds were evaluated in dual toroid waveguide phase shifter structures with temperature, pressure Rf power as variables Manganese substitution per formula unit for Fe+3 of 0.11 to 0.13 (2.2 to 2.6%) produced compounds which exhibited stable performance from magnetostrictive stresses in phaser structures. Ferrite phase shifters, Stress insensitive materials Manganese substitution in garnets, Magnetostrictive, Stresses in ferrite phasers.

  4. Apparatus and methods for using achromatic phase matching at high orders of dispersion

    DOEpatents

    Richman, Bruce; Trebino, Rick; Bisson, Scott; Sidick, Erkin

    2001-01-01

    Achromatic phase-matching (APM) is used for efficiently multiplying the frequency of broad bandwidth light by using a nonlinear optical medium comprising a second-harmonic generation (SHG) crystal. Stationary optical elements whose configuration, properties, and arrangement have been optimized to match the dispersion characteristics of the SHG crystal to at least the second order. These elements include a plurality of prismatic elements for directing an input light beam onto the SHG crystal such that each ray wavelength is aligned to match the phase-matching angle for the crystal at each wavelength of light to at least the second order and such that every ray wavelength overlap within the crystal.

  5. Silicon photonics thermal phase shifter with reduced temperature range

    DOEpatents

    Lentine, Anthony L; Kekatpure, Rohan D; DeRose, Christopher; Davids, Paul; Watts, Michael R

    2013-12-17

    Optical devices, phased array systems and methods of phase-shifting an input signal are provided. An optical device includes a microresonator and a waveguide for receiving an input optical signal. The waveguide includes a segment coupled to the microresonator with a coupling coefficient such that the waveguide is overcoupled to the microresonator. The microresonator received the input optical signal via the waveguide and phase-shifts the input optical signal to form an output optical signal. The output optical signal is coupled into the waveguide via the microresonator and transmitted by the waveguide. At an operating point of the optical device, the coupling coefficient is selected to reduce a change in an amplitude of the output optical signal and to increase a change in a phase of the output optical signal, relative to the input optical signal.

  6. Dual-function phase shifter for spin-wave logic applications

    NASA Astrophysics Data System (ADS)

    Hansen, Ulf-Hendrik; Demidov, Vladislav E.; Demokritov, Sergej O.

    2009-06-01

    We have studied experimentally the linear and nonlinear control over the phase accumulation in a spin-wave phase shifter, which is a key element for construction of spin-wave logic devices. The linear control is realized by creation of a local inhomogeneity of the bias magnetic field, whereas the nonlinear control is based on the shift in the spin-wave dispersion spectrum with the increase in the spin-wave amplitude. We show that in a single device these two mechanisms can have comparable efficiencies and relatively small cross talk, which allows their simultaneous use for realization of dual-argument logic operations.

  7. A K-Band Linear Phased Array Antenna Based on Ba(0.60)Sr(0.40)TiO3 Thin Film Phase Shifters

    NASA Technical Reports Server (NTRS)

    Romanofsky, R.; Bernhard, J.; Washington, G.; VanKeuls, F.; Miranda, F.; Cannedy, C.

    2000-01-01

    This paper summarizes the development of a 23.675 GHz linear 16-element scanning phased array antenna based on thin ferroelectric film coupled microstripline phase shifters and microstrip patch radiators.

  8. Millimeter-wave diode-grid phase shifters

    NASA Technical Reports Server (NTRS)

    Lam, Wayne W.; Stolt, Kjell S.; Jou, Christina F.; Luhmann, Neville C., Jr.; Chen, Howard Z.

    1988-01-01

    Monolithic diode grids have been fabricated on 2-cm square gallium-arsenide wafers with 1600 Schottky-barrier varactor diodes. Shorted diodes are detected with a liquid-crystal technique, and the bad diodes are removed with an ultrasonic probe. A small-aperture reflectometer that uses wavefront division interference was developed to measure the reflection coefficient of the grids. A phase shift of 70 deg with a 7-dB loss was obtained at 93 GHz when the bias on the diode grid was changed from -3 V to 1 V. A simple transmission-line grid model, together with the measured low-frequency parameters for the diodes, was shown to predict the measured performance over the entire capacitive bias range of the diodes, as well as over the complete reactive tuning range provided by a reflector behind the grid, and over a wide range of frequencies from 33 GHz to 141 GHz. This shows that the transmission-line model and the measured low-frequency diode parameters can be used to design an electronic beam-steering array and to predict its performance. An electronic beam-steering array made of a pair of grids using state-of-the-art diodes with 5-ohm series resistances would have a loss of 1.4 dB at 90 GHz.

  9. Wideband 360 degrees microwave photonic phase shifter based on slow light in semiconductor optical amplifiers.

    PubMed

    Xue, Weiqi; Sales, Salvador; Capmany, José; Mørk, Jesper

    2010-03-15

    In this work we demonstrate for the first time, to the best of our knowledge, a continuously tunable 360 degrees microwave phase shifter spanning a microwave bandwidth of several tens of GHz (up to 40 GHz). The proposed device exploits the phenomenon of coherent population oscillations, enhanced by optical filtering, in combination with a regeneration stage realized by four-wave mixing effects. This combination provides scalability: three hybrid stages are demonstrated but the technology allows an all-integrated device. The microwave operation frequency limitations of the suggested technique, dictated by the underlying physics, are also analyzed.

  10. Finite Ground Coplanar Waveguide Shunt MEMS Switches for Switched Line Phase Shifters

    NASA Technical Reports Server (NTRS)

    Ponchak, George E.; Simons, Rainee N.; Scardelletti, Maximillian; Varaljay, Nicholas C.

    2000-01-01

    Switches with low insertion loss and high isolation are required for switched line phase shifters and the transmit/receive switch at the front end of communication systems. A Finite Ground Coplanar (FGC) waveguide capacitive, shunt MEMS switch has been implemented on high resistivity Si. The switch has demonstrated an insertion loss of less than 0.3 dB and a return loss greater than 15 dB from 10 to 20, GHz. The switch design, fabrication, and characteristics are presented.

  11. Design characterization of an electronic steerable Ka-band antenna using liquid crystal phase shifters

    NASA Astrophysics Data System (ADS)

    Hoehn, A.; Hager, P. B.; Harder, J. T.

    Modern high data rate satellite communication systems increasingly utilize the Ka-band due to its ability to support higher bandwidth. Prior research work presented a copper-galvanically produced Ka-band horn array antenna and associated waveguide distribution network, mounted on a two axes mechanical steerable mechanism (LISAMS) for use aboard fast, low earth orbiting satellites. The current project, LISAES, investigates the feasibility of a similar horn array antenna, but fitted with liquid crystal phase shifters in the transmission path of each horn, which now allow steering of the antenna boresight through beam forming without the use of mechanically moving parts.

  12. Modeling non-saturated ferrite-based devices: Application to twin toroid ferrite phase shifters

    NASA Astrophysics Data System (ADS)

    Le Gouellec, A.; Vérissimo, G.; Laur, V.; Queffelec, P.; Albert, I.; Girard, T.

    2016-08-01

    This article describes a new set of tools developed to improve the conception and modeling of non-saturated ferrite-based devices such as twin toroid phase shifters. These new simulation tools benefit from a generalized permeability tensor model able to describe the permeability tensor of a ferrite sample whatever its magnetization state. This model is coupled to a homemade 3D multi-scale magnetostatic analysis program, which describes the evolution of the magnetization through the definition of a hysteresis loop in every mesh cell. These computed spectra are then integrated into 3D electromagnetic simulation software that retains the spatial variations of the ferrite properties by using freshly developed macro programming functions. This new approach allows the designers to accurately model complex ferrite devices such as twin toroid phase shifters. In particular, we demonstrated a good agreement between simulated and measured phase shifts as a function of applied current values with a predicted maximum phase shift of 0.96 times the measured value.

  13. Determination of birefringence and slow axis distribution using an interferometric measurement system with liquid crystal phase shifter.

    PubMed

    Nose, Toshiaki; Kamata, Keisuke; Takeuchi, Toru; Okano, Keiju; Fujita, Naoko; Muraguchi, Hajime; Ozaki, Noriaki; Honma, Michinori; Ito, Ryouta

    2014-11-01

    It is known that liquid crystal (LC) cells are useful as compact and easy-to-handle phase shifters that are readily coupled into the optics of standard microscope systems. Here, a uniformly aligned molecular LC phase shifter is introduced into a polarization microscope to attain a birefringence imaging system, using the phase-shift interferometric technique. Since the birefringence can be determined accurately only when the optical axis of the sample is parallel or perpendicular to the slow axis (variable axis) of the LC phase shifter, an improved data analysis method is proposed for determining the birefringence independently of the direction; a simple method of determining the slow axis distribution is also demonstrated. Measurements of the birefringence and slow axis distribution properties of a potato starch particle are demonstrated to confirm the novel determination method. PMID:25402881

  14. A high-power microwave circular polarizer and its application on phase shifter

    NASA Astrophysics Data System (ADS)

    Shao, Hao; Hu, Yongmei; Chang, Chao; Guo, Letian

    2016-04-01

    A high-power waveguide dual circular polarizer was theoretically designed and proof-of-principle was experimentally tested. It consists of two incident rectangular waveguides with a perpendicular H-plane junction, one circular waveguide with a pair of trapezoidal grooves coupled in E-plane at the top, a spherical crown located at the bottom, and an iris at the perpendicular junction of two rectangular waveguides. When wave incidents at one of the two separated rectangular waveguides, it, respectively, generates a left-hand circular polarized wave or a right-hand circular polarized wave in the circular waveguide. By adding a dumbbell-like metal plug driven with a high speed servomotor, a movable short circuit is formed along the circular waveguide to adjust the output RF phase of the rectangular port, realizing a high-speed high-power phase shifter. The C-band high power microwave (HPM) experiments were carried out, and the power capacity of the HPM polarizer and phase shifter was demonstrated to reach gigawatt level.

  15. Achromatic approach to phase-based multi-modal imaging with conventional X-ray sources.

    PubMed

    Endrizzi, Marco; Vittoria, Fabio A; Kallon, Gibril; Basta, Dario; Diemoz, Paul C; Vincenzi, Alessandro; Delogu, Pasquale; Bellazzini, Ronaldo; Olivo, Alessandro

    2015-06-15

    Compatibility with polychromatic radiation is an important requirement for an imaging system using conventional rotating anode X-ray sources. With a commercially available energy-resolving single-photon-counting detector we investigated how broadband radiation affects the performance of a multi-modal edge-illumination phase-contrast imaging system. The effect of X-ray energy on phase retrieval is presented, and the achromaticity of the method is experimentally demonstrated. Comparison with simulated measurements integrating over the energy spectrum shows that there is no significant loss of image quality due to the use of polychromatic radiation. This means that, to a good approximation, the imaging system exploits radiation in the same way at all energies typically used in hard-X-ray imaging. PMID:26193618

  16. ACHROMATIC EIGHT-OCTANT PHASE-MASK CORONAGRAPH USING PHOTONIC CRYSTAL

    SciTech Connect

    Murakami, Naoshi; Baba, Naoshi; Nishikawa, Jun; Yokochi, Kaito; Tamura, Motohide; Abe, Lyu

    2010-05-01

    We designed and manufactured a photonic-crystal mask which can be used for an achromatic eight-octant phase-mask (EOPM) coronagraph for direct detection of extrasolar planets. Laboratory experiments of the EOPM coronagraph were carried out using two laser light sources as a simulated star (wavelengths of 532 and 633 nm). As a result, we attained high extinction of the simulated starlight in both the wavelengths. Halo intensity levels of about 10{sup -6} and 10{sup -7} were achieved at an angular distance of 3 and 13{lambda}/D, respectively. We also discuss several issues, such as an effect of phase aberration on the coronagraphic performance, a transmittance of the proposed EOPM, and a novel two-channel coronagraphic configuration to improve system throughput.

  17. Improvement of decay time in nematic-liquid-crystal-loaded coplanar-waveguide-type microwave phase shifter by polymer stabilizing method

    NASA Astrophysics Data System (ADS)

    Nguyen, Thanh; Umeno, Shuhei; Higuchi, Hiroki; Kikuchi, Hirotsugu; Moritake, Hiroshi

    2014-01-01

    Polymer stabilization by UV light irradiation in nematic liquid crystals is proposed to improve the decay time of coplanar-waveguide-type microwave phase shifters. The effect of polymer concentration on the decay time of polymer-stabilized nematic liquid crystals is confirmed by a dielectric experiment on a liquid-crystal-sandwiched indium-tin-oxide (ITO) glass cell before loading into a coplanar-waveguide-type microwave phase shifter. The decay time, phase shift value, and insertion loss of microwave phase shifters with different polymer concentrations are measured. The decay time of polymer-stabilized nematic liquid crystals in the microwave phase shifter markedly decreases compared with that of pure nematic liquid crystals. It is confirmed that the use of polymer-stabilized nematic liquid crystals is effective to improve the response time of microwave phase shifters.

  18. Synthetic phase-shifting for optical testing: Point-diffraction interferometry without null optics or phase shifters

    PubMed Central

    Park, Ryeojin; Kim, Dae Wook; Barrett, Harrison H.

    2013-01-01

    An innovative iterative search method called the synthetic phase-shifting (SPS) algorithm is proposed. This search algorithm is used for maximum-likelihood (ML) estimation of a wavefront that is described by a finite set of Zernike Fringe polynomials. In this paper, we estimate the coefficient, or parameter, values of the wavefront using a single interferogram obtained from a point-diffraction interferometer (PDI). In order to find the estimates, we first calculate the squared-difference between the measured and simulated interferograms. Under certain assumptions, this squared-difference image can be treated as an interferogram showing the phase difference between the true wavefront deviation and simulated wavefront deviation. The wavefront deviation is the difference between the reference and the test wavefronts. We calculate the phase difference using a traditional phase-shifting technique without physical phase-shifters. We present a detailed forward model for the PDI interferogram, including the effect of the finite size of a detector pixel. The algorithm was validated with computational studies and its performance and constraints are discussed. A prototype PDI was built and the algorithm was also experimentally validated. A large wavefront deviation was successfully estimated without using null optics or physical phase-shifters. The experimental result shows that the proposed algorithm has great potential to provide an accurate tool for non-null testing. PMID:24216862

  19. Broadband, Low-Loss Phase Shifters Based on Thin Ferroelectric Films

    NASA Technical Reports Server (NTRS)

    Romanofsky, Robert

    2004-01-01

    Several different types of microwave transmission line phase shifters based on thin ferroelectic films have been developed at the NASA Glenn Research Center. These include a series of coupled microstrip lines, slotline incorporating Marchand balms, odd-mode coplanar strips, and hybrid devices incorporating a switch to toggle the output termination between an open and virtual short circuit. A review of the theory of operation of each of these devices will be presented along with measured performance. Also, devices of the first variety have been subjected to total dose (proton) radiation exposure using a 200 MeV beam energy with a total dose up to nearly 1 kRad (Si). Results of these radiation tests will be discussed.

  20. Aluminum nitride electro-optic phase shifter for backend integration on silicon.

    PubMed

    Zhu, Shiyang; Lo, Guo-Qiang

    2016-06-13

    An AlN electro-optic phase shifter with a parallel plate capacitor structure is fabricated on Si using the back-end complementary metal-oxide-semiconductor technology, which is feasible for multilayer photonics integration. The modulation efficiency (Vπ⋅Lπ product) measured from the fabricated waveguide-ring resonators and Mach-Zehnder Interferometer (MZI) modulators near the 1550-nm wavelength is ∼240 V⋅cm for the transverse electric (TE) mode and ∼320 V⋅cm for the transverse magnetic (TM) mode, from which the Pockels coefficient of the deposited AlN is deduced to be ∼1.0 pm/V for both TE and TM modes. The methods for further modulation efficiency improvement are addressed.

  1. All-prism achromatic phase matching for tunable second-harmonic generation

    SciTech Connect

    Richman, Bruce A.; Bisson, Scott E.; Trebino, Rick; Jacobson, Alexander

    1999-05-01

    Achromatic phase matching (APM) involves dispersing the light entering a nonlinear optical crystal so that a wide range of wavelengths is simultaneously phase matched. We constructed an APM apparatus consisting of six prisms, the final dispersion angle of which was optimized to match to second order in wavelength the type I phase-matching angle of {beta} barium borate (BBO). With this apparatus, we doubled tunable fundamental light from 620 to 700 nm in wavelength using a 4-mm-long BBO crystal. An analogous set of six prisms after the BBO crystal, optimized to second order in second-harmonic wavelength, realigned the output second-harmonic beams. Computer simulations predict that adjustment of a single prism can compensate angular misalignment of any or all the prisms before the crystal, and similarly for the prisms after the crystal. We demonstrated such compensations with the experimental device. The simulations also indicate that the phase-matching wavelength band can be shifted and optimized for different crystal lengths. {copyright} 1999 Optical Society of America

  2. All-prism achromatic phase matching for tunable second-harmonic generation.

    PubMed

    Richman, B A; Bisson, S E; Trebino, R; Sidick, E; Jacobson, A

    1999-05-20

    Achromatic phase matching (APM) involves dispersing the light entering a nonlinear optical crystal so that a wide range of wavelengths is simultaneously phase matched. We constructed an APM apparatus consisting of six prisms, the final dispersion angle of which was optimized to match to second order in wavelength the type I phase-matching angle of beta barium borate (BBO). With this apparatus, we doubled tunable fundamental light from 620 to 700 nm in wavelength using a 4-mm-long BBO crystal. An analogous set of six prisms after the BBO crystal, optimized to second order in second-harmonic wavelength, realigned the output second-harmonic beams. Computer simulations predict that adjustment of a single prism can compensate angular misalignment of any or all the prisms before the crystal, and similarly for the prisms after the crystal. We demonstrated such compensation with the experimental device. The simulations also indicate that the phase-matching wavelength band can be shifted and optimized for different crystal lengths.

  3. Optically tunable full 360° microwave photonic phase shifter using three cascaded silicon-on-insulator microring resonators

    NASA Astrophysics Data System (ADS)

    Ehteshami, Nasrin; Zhang, Weifeng; Yao, Jianping

    2016-08-01

    A broadband optically tunable microwave phase shifter with a tunable phase shift covering the entire 360° range using three cascaded silicon-on-insulator (SOI) microring resonators (MRRs) that are optically pumped is proposed and experimentally demonstrated. The phase tuning is implemented based on the thermal nonlinear effect in the MRRs. By optically pumping the MRRs, the stored light in the MRRs is absorbed due to two photon absorption (TPA) to generate free carriers, which result in free carrier absorption (FCA). The FCA effect would lead to the heating of the MRRs and cause a redshift in the phase response, which is used to implement a microwave phase shifter with a tunable phase shift. The device is designated and fabricated on an SOI platform, which is experimentally evaluated. The experimental results show that by optically pumping the MRRs, a broadband microwave photonic phase shifter with a bandwidth of 7 GHz from 16 to 23 GHz with a tunable phase shift covering the entire 360° phase shift range is achieved.

  4. Temperature- and wavelength-insensitive parametric amplification enabled by noncollinear achromatic phase-matching

    PubMed Central

    Tang, Daolong; Ma, Jingui; Wang, Jing; Zhou, Bingjie; Xie, Guoqiang; Yuan, Peng; Zhu, Heyuan; Qian, Liejia

    2016-01-01

    Optical parametric chirped-pulse amplification (OPCPA) has been demonstrated to be a promising approach for pushing femtosecond pulses towards ultra-high peak powers. However, the future success of OPCPA strongly relies on the ability to manipulate its phase-matching (PM) configuration. When a high average power pump laser is involved, the thermal effects in nonlinear crystals induce phase-mismatch distortions that pose an inherent limitation on the conversion efficiency. Here, we demonstrate that the noncollinear configuration previously adopted for wavelength-insensitive PM can be employed for temperature-insensitive PM when the noncollinear angle is properly reset. Simultaneous temperature- and wavelength-insensitive PM is realized for the first time by imposing such a temperature-insensitive noncollinear configuration with an angularly dispersed seed signal. Based on the lithium triborate crystal, the proposed noncollinear achromatic PM has a thermal acceptance 6 times larger than that of the conventional wavelength-insensitive noncollinear PM and has a sufficient spectral acceptance to support pulse durations of ~20 fs at 800 nm. These achievements open new possibilities for generating ultra-high peak power lasers with high average power. PMID:27786299

  5. Design, development and characterization of an x-band 5 bit DMTL phase shifter using an inline MEMS bridge and MAM capacitors

    NASA Astrophysics Data System (ADS)

    Dey, Sukomal; Koul, Shiban K.

    2014-09-01

    A radio frequency micro-electro-mechanical system (RF-MEMS) 5 bit phase shifter based on a distributed MEMS transmission line concept with excellent phase accuracy and good repeatability is presented in this paper. The phase shifter is built with three fixed-fixed beams; one is switchable with electrostatic actuation and the other two are fixed for a metal-air-metal (MAM) capacitor. The design is based on a coplanar waveguide (CPW) configuration using alumina substrate. Gold-based surface micromachining is used to develop the individual primary phase bits (11.25°/22.5°/45°/90°/180°), which are fundamental building blocks of the complete 5 bit phase shifter. All of the primary phase bits are cascaded together to build the complete phase shifter. Detailed design methodology and performance analysis of the unit cell phase shifter has been carried out with structural and parametric optimization using an in-line bridge and MAM capacitors. The mechanical, electrical, transient, intermodulation distortion (IMD), temperature distribution, power handling and loss performances of the MEMS bridge have been experimentally obtained and validated using simulations up to reasonable extent. A single unit cell is able to provide 31 dB return loss, maximum insertion loss of 0.085 dB and a differential phase shift of 5.95° (at 10 GHz) over the band of interest. Furthermore, all primary phase bits are individually tested to ensure overall optimum phase shifter performance. The complete 5 bit phase shifter demonstrates an average insertion loss of 4.72 dB with return loss of better than 12 dB within 8-12 GHz using periodic placement of 62 unit cells and a maximum phase error of ±3.2° has been obtained at 10 GHz. Finally, the x-band 5 bit phase shifter is compared with the present state-of-the-art. The performance of the 5 bit phase shifter when mounted inside a test jig has been experimentally investigated and the results are presented. The total area of

  6. Slow-Wave Phase Shifters, Based on Thin Ferroelectric Films, for Reflectarray Antennas. Frequency-Agile Radio: Systems and Technlogies, WMG 139

    NASA Technical Reports Server (NTRS)

    Romanofsky, Robert R.

    2006-01-01

    We have developed relatively broadband K- and Ka-band phase shifters using synthetic (slow-wave) transmission lines employing coupled microstripline "varactors". The tunable coupled microstripline circuits are based on laser ablated BaSrTiO films on lanthanum aluminate substrates. A model and design criteria for these novel circuits will be presented, along with measured performance including anomalous phase delay characteristics. The critical role of phase shifter loss and transient response in reflectarray antennas will be emphasized.

  7. Thin-Film Ferro Electric-Coupled Microstripline Phase Shifters With Reduced Device Hysteresis

    NASA Technical Reports Server (NTRS)

    Miranda, Felix A.; Romanofsky, Robert; Mueller, Carl H.; VanKeuls, Frederick

    2010-01-01

    This work deals with the performance of coupled microstripline phase shifters (CMPS) fabricated using BaxSr 1 -xTiO 3 (BST) ferroelectric thin films. The CMPS were fabricated using commercially available pulsed laser deposition BST films with Ba:Sr ratios of 30:70 and 20:80. Microwave characterization of these CMPS was performed at upper Kuband frequencies, particularly at frequencies near 16 and 18 GHz. X-ray diffraction studies indicate that the 30:70 films exhibit almost a 1:1 ratio between the in-plane and out-of-plane lattice parameters, suggesting that their cubics create strain -free films suitable for producing CMPS devices with reduced hysteresis in the paraelectric state. The quality of performance of the CMPS was studied based on their relative phase shift and insertion loss within the DC bias range of 0 to 400 V (i.e., E-field ranges within 0 to 53 V/micron). The performance of the CMPS was tested as a function of temperature to investigate their operation in the paraelectric, as well as in the ferroelectric, state (i.e., above and below the Curie temperature, respectively). The novel behavior discussed here is based on the experimental observation of the CMPS. This behavior, observed for the aforementioned cation ratio, highlights the relevance of good crystalline structure for high-quality CMPS.

  8. Integrated Optics Achromatic Nuller for Stellar Interferometry

    NASA Technical Reports Server (NTRS)

    Ksendzov, Alexander

    2012-01-01

    This innovation will replace a beam combiner, a phase shifter, and a mode conditioner, thus simplifying the system design and alignment, and saving weight and space in future missions. This nuller is a dielectric-waveguide-based, four-port asymmetric coupler. Its nulling performance is based on the mode-sorting property of adiabatic asymmetric couplers that are intrinsically achromatic. This nuller has been designed, and its performance modeled, in the 6.5-micrometer to 9.25-micrometer spectral interval (36% bandwidth). The calculated suppression of starlight for this 15-cm-long device is 10(exp -5) or better through the whole bandwidth. This is enough to satisfy requirements of a flagship exoplanet-characterization mission. Nulling interferometry is an approach to starlight suppression that will allow the detection and spectral characterization of Earth-like exoplanets. Nulling interferometers separate the light originating from a dim planet from the bright starlight by placing the star at the bottom of a deep, destructive interference fringe, where the starlight is effectively cancelled, or nulled, thus allowing the faint off-axis light to be much more easily seen. This process is referred to as nulling of the starlight. Achromatic nulling technology is a critical component that provides the starlight suppression in interferometer-based observatories. Previously considered space-based interferometers are aimed at approximately 6-to-20-micrometer spectral range. While containing the spectral features of many gases that are considered to be signatures of life, it also offers better planet-to-star brightness ratio than shorter wavelengths. In the Integrated Optics Achromatic Nuller (IOAN) device, the two beams from the interferometer's collecting telescopes pass through the same focusing optic and are incident on the input of the nuller.

  9. MEMS-tunable composite right/left-handed (CRLH) transmission line and its application to a phase shifter

    NASA Astrophysics Data System (ADS)

    Hwang, Sung-Hyun; Jang, Taehee; Kim, Jong-Man; Kim, Yong-Kweon; Lim, Sungjoon; Baek, Chang-Wook

    2011-12-01

    This paper reports a novel compact tunable composite right/left-handed transmission line (CRLH TL) with multi-state phase tunability using integrated microelectromechanical system (MEMS) switches and its application to a phase shifter. It is possible to select multiple states with different positive/negative phase responses. The phase states can be determined by controlling the admittance of capacitors and impedance of inductors through MEMS switch operations. The designed devices are analyzed using electromagnetic and circuit simulations. The propagation characteristics and phase lead/lag properties of the devices are investigated. The designed device can be operated as a 90°/-90° phase tunable CRLH TL at 8 GHz and a four-state phase shifter at 9.5 GHz by switch configuration. At 8 GHz, the phase responses of the device were 87° of the phase lead and -80° of the phase lag for the left-handed (LH) and right-handed (RH) states, respectively. At 9.5 GHz, the phase of each state varies among 26.7°, 14.6°, -6.7°, and -11.5°, where the first two states are in the LH region and the others are in the RH region. At 9-15 GHz, insertion losses are measured to be <2.6 dB, and return losses are >10 dB.

  10. Ka-band reliable and compact 3-bit true-time-delay phase shifter using MEMS single-pole-eight-throw switching networks

    NASA Astrophysics Data System (ADS)

    Koul, Shiban K.; Dey, Sukomal; Poddar, Ajay K.; Rohde, Ulrich L.

    2016-10-01

    This paper presents a radio frequency micro-electromechanical system (RF MEMS) based 3-bit phase shifter using MEMS single-pole-eight-throw (SP8T) switches. Devices are fabricated on 635 µm alumina substrate utilizing on the coplanar waveguide (CPW) transmission line. Single switch dimensions are 0.14  ×  0.23 mm2 which is much smaller than Si-on-insulator switches. The symmetric and compact SP8T switch is the primary building block of the 3-bit phase shifter. The SP8T switch results in isolation levels of 31-15 dB, return loss of 33-18 dB and insertion loss of 0.6-1.9 dB, respectively, at 26-40 GHz. Later, two SP8T switches are connected back to back to develop the 3-bit phase shifter using different delay lines at 35 GHz. Finally, the phase shifter provides average return loss of better than 14 dB and average insertion loss of 4.4 dB over the 34.75-35.25 GHz. Measured average phase error is less than 0.98° at 35 GHz. The total area of the fabricated 3-bit phase shifter is 5.95 mm2. SP8T switches are capable of handling 0.1-1 W of power up to 100 million cycles which is sufficient power handling capability for wireless communication systems. Reliability of the phase shifter is extensively characterized with different incident RF powers at room temperature (25°C) and discussed in detail. To the best of the authors’ knowledge, this is the first reported MEMS 3-bit phase shifter in the literature that has used a minimum number of switching elements per phase state.

  11. Voltage-controlled liquid-crystal terahertz phase shifter with indium-tin-oxide nanowhiskers as transparent electrodes.

    PubMed

    Yang, Chan-Shan; Tang, Tsung-Ta; Chen, Po-Han; Pan, Ru-Pin; Yu, Peichen; Pan, Ci-Ling

    2014-04-15

    Indium-tin-oxide nanowhiskers were employed as transparent electrodes in a liquid-crystal terahertz phase shifter. Transmittance of the device was as high as ∼75%. Phase shift exceeding π/2 at 1.0 THz is achieved in a ∼500  μm-thick cell. The driving voltage required for the device operating as a quarter-wave plate was as low as 17.68 V (rms), an improvement of nearly an order of magnitude over previous work.

  12. 10-25 GHz frequency reconfigurable MEMS 5-bit phase shifter using push-pull actuator based toggle mechanism

    NASA Astrophysics Data System (ADS)

    Dey, Sukomal; Koul, Shiban K.

    2015-06-01

    This paper presents a frequency tunable 5-bit true-time-delay digital phase shifter using radio frequency microelectromechanical system (RF MEMS) technology. The phase shifter is based on the distributed MEMS transmission line (DMTL) concept utilizing a MEMS varactor. The main source of frequency tuning in this work is a bridge actuation mechanism followed by capacitance variation. Two stages of actuation mechanisms (push and pull) are used to achieve a 2:1 tuning ratio. Accurate control of the actuation voltage between the pull to push stages contributes differential phase shift over the band of interest. The functional behavior of the push-pull actuation over the phase shifter application is theoretically established, experimentally investigated and validated with simulation. The phase shifter is fabricated monolithically using a gold based surface micromachining process on an alumina substrate. The individual primary phase-bits (11.25°/22.5°/45°/90°/180°) that are the fundamental building blocks of the complete 5-bit phase shifter are designed, fabricated and experimentally characterized from 10-25 GHz for specific applications. Finally, the complete 5-bit phase shifter demonstrates an average phase error of 4.32°, 2.8°, 1° and 1.58°, an average insertion loss of 3.76, 4.1, 4.2 and 4.84 dB and an average return loss of 11.7, 12, 14 and 11.8 dB at 10, 12, 17.2 and 25 GHz, respectively. To the best of the authors’ knowledge, this is the first reported band tunable stand alone 5-bit phase shifter in the literature which can work over the large spectrum for different applications. The total area of the 5-bit phase shifter is 15.6 mm2. Furthermore, the cold-switched reliability of the unit cell and the complete 5-bit MEMS phase shifter are extensively investigated and presented.

  13. Triband phase shifter design using split-ring resonator and complementary split-ring resonator-loaded ground plane for wireless applications

    NASA Astrophysics Data System (ADS)

    Kulandhaisamy, Indhumathi; Shrivastav, Arun Kumar; Kanagasabai, Malathi; Kizhekke Pakkathillam, Jayaram

    2015-10-01

    This paper presents the design of a novel linear analog planar phase shifter deploying split-ring resonator (SRR) and complementary split-ring resonator (CSRR) structures. Based on the advantages of these structures, a triband phase shifter is designed for multiple target systems to operate at 0.85, 1.69, and 2.46 GHz bands finding applications for European RFIDs, Satellite Radio Broadcast System, Mobile Services, and ISM Band, respectively. The effect of SRR and CSRR coupling with host transmission line is also analyzed on the basis of Bloch mode theory and the modes are validated through Eigen mode analysis. The proposed phase shifter design shows a good agreement between simulated and measured results. A 90° ± 8° shift in phase is observed at lower and upper bands, and a 135° ± 8° shift is observed in center band with reasonable group delay components.

  14. Enhancement of the low-frequency response of a reflective semiconductor optical amplifier slow light-based microwave phase shifter by forced coherent population oscillations

    NASA Astrophysics Data System (ADS)

    Meehan, Aidan; Connelly, Michael J.

    2014-05-01

    The enhancement of the low frequency gain response of a microwave phase shifter based on slow light in a bulk reflective semiconductor optical amplifier (RSOA), by using forced coherent population oscillations (FCPO), is experimentally demonstrated. FCPO is achieved by simultaneously modulating the input optical power and bias current. The beat signal gain improvement ranges from 45 to 0 dB over a frequency range of 0.5 to 2.5 GHz, thereby improving the noise performance of the phase shifter. Tunable phase shifts of up to 40º are possible over this frequency range.

  15. A gallium-arsenide digital phase shifter for clock and control signal distribution in high-speed digital systems

    NASA Technical Reports Server (NTRS)

    Fouts, Douglas J.

    1992-01-01

    The design, implementation, testing, and applications of a gallium-arsenide digital phase shifter and fan-out buffer are described. The integrated circuit provides a method for adjusting the phase of high-speed clock and control signals in digital systems, without the need for pruning cables, multiplexing between cables of different lengths, delay lines, or similar techniques. The phase of signals distributed with the described chip can be dynamically adjusted in eight different steps of approximately 60 ps per step. The IC also serves as a fan-out buffer and provides 12 in-phase outputs. The chip is useful for distributing high-speed clock and control signals in synchronous digital systems, especially if components are distributed over a large physical area or if there is a large number of components.

  16. Ultra-wideband 4 × 4 Phased Array Containing Exponentially Tapered Slot Antennas and a True-Time Delay Phase Shifter at UHF

    NASA Astrophysics Data System (ADS)

    Schmitz, J.; Jung, M.; Bonney, J.; Caspary, R.; Schüür, J.; Schöbel, J.

    For angular scanning a true-time array is developed for UHF ultra-wideband (UWB) applications in time and/or frequency domain. It is based on a 4 × 4 array with antipodal exponentially tapered slot antennas (ETSA, Vivaldi) and a 3-bit phase shifter. Distances of antenna elements are designed to be compromise between gain, scanning angle, side/grating lobe levels. The uniform spaced and fed array maximizes the overall gain. After defining the antenna shape, corrugations are introduced to improve antenna matching and gain pattern. Nine equally spaced beam positions for a 90° scanning angle are induced by an optimized 3-bit phase shifter on high permittivity substrate, while 4 bits are usually needed. Parasitic resonances are avoided by using PIN diodes in single pole double throw configuration. All components and the complete array system are simulated and verified in frequency domain with good agreement. Adaptation to UWB pulses is possible.

  17. Design and development of a CPW-based 5-bit switched-line phase shifter using inline metal contact MEMS series switches for 17.25 GHz transmit/receive module application

    NASA Astrophysics Data System (ADS)

    Dey, Sukomal; Koul, Shiban K.

    2014-01-01

    A radio frequency micro-electro-mechanical system (RF-MEMS) phase shifter based on switchable delay line concept with maximum desirable phase shift and good reliability is presented in this paper. The phase shifter is based on the switchable reference and delay line configurations with inline metal contact series switches that employs MEMS systems based on electrostatic actuation and implemented using coplanar waveguide (CPW) configuration. Electromechanical behaviour of the MEMS switch has been extensively investigated using commercially available simulation tools and validated using system level simulation. A detailed design and performance analysis of the phase shifter has been carried out as a function of various structural parameters with reference to the gold-based surface micromachining process on alumina substrate. The mechanical, electrical, transient, intermodulation distortion (IMD) and loss performance of an MEMS switch have been experimentally investigated. The individual primary phase-bits (11.25°/22.5°/45°/90°/180°) that are fundamental building blocks of a complete 5-bit phase shifter have been designed, fabricated and experimentally characterized. Furthermore, two different 5-bit switched-line phase shifters, that lead to 25% size reduction and result in marked improvement in the reliability of the complete 5-bit phase shifter with 30 V actuation voltage, have been developed. The performance comparison between two different CPW-based switched-line phase shifters have been extensively investigated and validated. The complete 5-bit phase shifter demonstrates an average insertion loss of 5.4 dB with a return loss of better than 14 dB at 17.25 GHz. The maximum phase error of 1.3° has been obtained at 17.25 GHz from these 5-bit phase shifters.

  18. Compaction managed mirror bend achromat

    DOEpatents

    Douglas, David

    2005-10-18

    A method for controlling the momentum compaction in a beam of charged particles. The method includes a compaction-managed mirror bend achromat (CMMBA) that provides a beamline design that retains the large momentum acceptance of a conventional mirror bend achromat. The CMMBA also provides the ability to tailor the system momentum compaction spectrum as desired for specific applications. The CMMBA enables magnetostatic management of the longitudinal phase space in Energy Recovery Linacs (ERLs) thereby alleviating the need for harmonic linearization of the RF waveform.

  19. Research on a Defects Detection Method in the Ferrite Phase Shifter Cementing Process Based on a Multi-Sensor Prognostic and Health Management (PHM) System

    PubMed Central

    Wan, Bo; Fu, Guicui; Li, Yanruoyue; Zhao, Youhu

    2016-01-01

    The cementing manufacturing process of ferrite phase shifters has the defect that cementing strength is insufficient and fractures always appear. A detection method of these defects was studied utilizing the multi-sensors Prognostic and Health Management (PHM) theory. Aiming at these process defects, the reasons that lead to defects are analyzed in this paper. In the meanwhile, the key process parameters were determined and Differential Scanning Calorimetry (DSC) tests during the cure process of resin cementing were carried out. At the same time, in order to get data on changing cementing strength, multiple-group cementing process tests of different key process parameters were designed and conducted. A relational model of cementing strength and cure temperature, time and pressure was established, by combining data of DSC and process tests as well as based on the Avrami formula. Through sensitivity analysis for three process parameters, the on-line detection decision criterion and the process parameters which have obvious impact on cementing strength were determined. A PHM system with multiple temperature and pressure sensors was established on this basis, and then, on-line detection, diagnosis and control for ferrite phase shifter cementing process defects were realized. It was verified by subsequent process that the on-line detection system improved the reliability of the ferrite phase shifter cementing process and reduced the incidence of insufficient cementing strength defects. PMID:27517935

  20. Research on a Defects Detection Method in the Ferrite Phase Shifter Cementing Process Based on a Multi-Sensor Prognostic and Health Management (PHM) System.

    PubMed

    Wan, Bo; Fu, Guicui; Li, Yanruoyue; Zhao, Youhu

    2016-01-01

    The cementing manufacturing process of ferrite phase shifters has the defect that cementing strength is insufficient and fractures always appear. A detection method of these defects was studied utilizing the multi-sensors Prognostic and Health Management (PHM) theory. Aiming at these process defects, the reasons that lead to defects are analyzed in this paper. In the meanwhile, the key process parameters were determined and Differential Scanning Calorimetry (DSC) tests during the cure process of resin cementing were carried out. At the same time, in order to get data on changing cementing strength, multiple-group cementing process tests of different key process parameters were designed and conducted. A relational model of cementing strength and cure temperature, time and pressure was established, by combining data of DSC and process tests as well as based on the Avrami formula. Through sensitivity analysis for three process parameters, the on-line detection decision criterion and the process parameters which have obvious impact on cementing strength were determined. A PHM system with multiple temperature and pressure sensors was established on this basis, and then, on-line detection, diagnosis and control for ferrite phase shifter cementing process defects were realized. It was verified by subsequent process that the on-line detection system improved the reliability of the ferrite phase shifter cementing process and reduced the incidence of insufficient cementing strength defects. PMID:27517935

  1. Research on a Defects Detection Method in the Ferrite Phase Shifter Cementing Process Based on a Multi-Sensor Prognostic and Health Management (PHM) System.

    PubMed

    Wan, Bo; Fu, Guicui; Li, Yanruoyue; Zhao, Youhu

    2016-08-10

    The cementing manufacturing process of ferrite phase shifters has the defect that cementing strength is insufficient and fractures always appear. A detection method of these defects was studied utilizing the multi-sensors Prognostic and Health Management (PHM) theory. Aiming at these process defects, the reasons that lead to defects are analyzed in this paper. In the meanwhile, the key process parameters were determined and Differential Scanning Calorimetry (DSC) tests during the cure process of resin cementing were carried out. At the same time, in order to get data on changing cementing strength, multiple-group cementing process tests of different key process parameters were designed and conducted. A relational model of cementing strength and cure temperature, time and pressure was established, by combining data of DSC and process tests as well as based on the Avrami formula. Through sensitivity analysis for three process parameters, the on-line detection decision criterion and the process parameters which have obvious impact on cementing strength were determined. A PHM system with multiple temperature and pressure sensors was established on this basis, and then, on-line detection, diagnosis and control for ferrite phase shifter cementing process defects were realized. It was verified by subsequent process that the on-line detection system improved the reliability of the ferrite phase shifter cementing process and reduced the incidence of insufficient cementing strength defects.

  2. High-Precision Time Delay Control with Continuous Phase Shifter for Pump-Probe Experiments Using Synchrotron Radiation Pulses

    SciTech Connect

    Tanaka, Yoshihito; Ohshima, Takashi; Moritomo, Yutaka; Tanaka, Hitoshi; Takata, Masaki

    2010-06-23

    Brilliant pulsed x-ray synchrotron radiation (SR) is useful for pump-probe experiment such as time-resolved x-ray diffraction, x-ray absorption fine structure, and x-ray spectroscopy. For laser pump-SR x-ray probe experiments, short pulsed lasers are generally synchronized to the SR master oscillator controlling the voltage for acceleration of electron bunches in an accelerator, and the interval between the laser and the SR pulses is changed around the time scale of target phenomenon. Ideal delay control produces any time delay as keeping the time-precision and pointing-stability of optical pulses at a sample position. We constructed the time delay control module using a continuous phase shifter of radio frequency signal and a frequency divider, which can produce the delayed trigger pulses to the laser without degradation of the time precision and the pointing stability. A picoseconds time-resolved x-ray diffraction experiment was demonstrated at SPring-8 storage ring for fast lattice response by femtosecond pulsed laser irradiation, and suggested the possibility of accurate sound velocity measurement. A delay control unit operating with subpicosecond precision has also been designed for femtosecond pump-probe experiments using a free electron laser at SPring-8 campus.

  3. Full range complex spectral domain optical coherence tomography without additional phase shifters.

    PubMed

    Baumann, Bernhard; Pircher, Michael; Götzinger, Erich; Hitzenberger, Christoph K

    2007-10-01

    We demonstrate a new full range complex spectral domain optical coherence tomography (FRC SD-OCT) method. Other than FRC SD-OCT systems reported in literature, which employed devices such as electro-/acousto optic modulators or piezo-driven mirrors providing the phase modulations necessary for retrieval of the complex-valued signal, the system presented works without any additional phase shifting device. The required phase shift is introduced by the galvanometer scanner used for transversally scanning the sample beam. By means of a slight displacement of the probe beam with respect to the scanning mirror's pivot axis, the sample arm length and thus the phase is continuously modulated as the beam is scanned in lateral direction. From such modulated spectral data, the complex-valued data yielding a twofold increase of accessible depth range can be calculated using an algorithm based on the Hilbert transform. To demonstrate the performance of our method quantitative measurements of the suppression of mirror images as a function of induced phase shift were performed. In order to validate the FRC SD-OCT technique for high-speed imaging of biological tissue, we present full-range images of the human anterior chamber in vivo. PMID:19550607

  4. Achromatic phase-matching second harmonic generation for a tunable laser

    DOEpatents

    Jacobson, Alexander Gerson; Bisson, Scott; Trebino, Rick

    1998-01-01

    An optical system uses a nonlinear optical medium to alter the frequency of a relatively narrow band light source tunable over a plurality of different frequencies using an optical system for passively directing light to the nonlinear medium at a correct phase matching angle. In this manner, the light from the tunable light source can be efficiently frequency-doubled or frequency-tripled without the need of moving parts. An all prism design provides a system of optimal efficiency.

  5. Achromatic phase-matching second harmonic generation for a tunable laser

    DOEpatents

    Jacobson, A.G.; Bisson, S.; Trebino, R.

    1998-01-20

    An optical system uses a nonlinear optical medium to alter the frequency of a relatively narrow band light source tunable over a plurality of different frequencies using an optical system for passively directing light to the nonlinear medium at a correct phase matching angle. In this manner, the light from the tunable light source can be efficiently frequency-doubled or frequency-tripled without the need of moving parts. An all prism design provides a system of optimal efficiency. 6 figs.

  6. A substrate-modified CPW-based linear microwave phase shifter

    NASA Astrophysics Data System (ADS)

    Kulandhaisamy, Indhumathi; Kumar, Shrivastav Arun; Kanagasabai, Malathi

    2015-10-01

    A novel method for achieving linear phase shift is proposed over the frequency range of 2 - 6 GHz. Dielectric characterization of FR4 substrate interfaced with air as well as water produces the phase shift. The substrate property is modified by introducing a plain rectangular packet and W-shaped packet within the FR4 substrate. The overall dimension of the proposed structure is 30 × 60 mm2. Across the entire proposed frequency range, the reflection coefficient is less than -10 dB. The proposed coplanar waveguide with water- and air-stacked FR4 substrate is simulated, fabricated, and measured for its linear phase shifting characteristics analyzed in ISM 2.45, 3.3, and 5.8 GHz bands. The analysis over the entire band depicts that the differential shift in phase is directly proportional to the effective dielectric constant of the material used. The design will be more useful in automotive anti-collision radars in military, cellular base stations, and satellite communications.

  7. Investigation of aging effects from high voltage profiles in ceramic phase shifter materials

    SciTech Connect

    Stowell, S.; Sengupta, L.C.; Ngo, E.; O`Day, M.E.; Lancto, R.

    1994-12-01

    Ceramic composite materials comprised of Ba(0.60)Sr(0.40)TiO3 and Alumina and other non ferroelectric oxides have been fabricated for use in phased array antennas. These composites have shown superior electronic properties and have been incorporated into several antenna designs. However, minimal testing has been accomplished to determine the electrical aging and fatigue caused by the large electric fields required to operate these devices. In this paper, a systematic study of the effect of the application of large fields will he presented. The electronic properties of the BSTO-Oxide composites (pre-voltage application) will be presented and include the dielectric constant, loss tangent, and tunability (change in dielectric constant with applied field). The study of the change in the electronic properties after large voltages applications include results on the electronic aging and fatigue of the material and appropriate conditioning of the material for application in phased array antenna systems.

  8. Achromatic shearing phase sensor for generating images indicative of measure(s) of alignment between segments of a segmented telescope's mirrors

    NASA Technical Reports Server (NTRS)

    Stahl, H. Philip (Inventor); Walker, Chanda Bartlett (Inventor)

    2006-01-01

    An achromatic shearing phase sensor generates an image indicative of at least one measure of alignment between two segments of a segmented telescope's mirrors. An optical grating receives at least a portion of irradiance originating at the segmented telescope in the form of a collimated beam and the collimated beam into a plurality of diffraction orders. Focusing optics separate and focus the diffraction orders. Filtering optics then filter the diffraction orders to generate a resultant set of diffraction orders that are modified. Imaging optics combine portions of the resultant set of diffraction orders to generate an interference pattern that is ultimately imaged by an imager.

  9. Characterization of (Ba(0.5)Sr(0.5)) TiO3 Thin Films for Ku-Band Phase Shifters

    NASA Technical Reports Server (NTRS)

    Mueller, Carl H.; VanKeuls, Fredrick W.; Romanofsky, Robert R.; Miranda, Felix A.; Warner, Joseph D.; Canedy, Chadwick L.; Ramesh, Rammamoorthy

    1999-01-01

    The microstructural properties of (Ba(0.5)Sr(0.5)TiO3) (BSTO) thin films (300, 700, and 1400 nm thick) deposited on LaAlO3 (LAO) substrates were characterized using high-resolution x-ray diffractometry. Film crystallinity was the parameter that most directly influenced tunability, and we observed that a) the crystalline quality was highest in the thinnest film and progressively degraded with increasing film thickness; and b) strain at the film/substrate interface was completely relieved via dislocation formation. Paraelectric films such as BSTO offer an attractive means of incorporating low-cost phase shifter circuitry into beam-steerable reflectarray antennas.

  10. Design and development of a surface micro-machined push-pull-type true-time-delay phase shifter on an alumina substrate for Ka-band T/R module application

    NASA Astrophysics Data System (ADS)

    Dey, Sukomal; Koul, Shiban K.

    2012-12-01

    A radio frequency micro-electro-mechanical system (RF-MEMS) phase shifter based on the distributed MEMS transmission line (DMTL) concept towards maximum achievable phase shift with low actuation voltage with good figure of merit (FOM) is presented in this paper. This surface micro-machined analog DMTL phase shifter demonstrates low power consumption for implementation in a Ka-band transmit/receive (T/R) module. The push-pull-type switch has been designed and optimized with an analytical method and validated with simulation, which is the fundamental building block of the design of a true-time-delay phase shifter. Change in phase has been designed and optimized in push and pull states with reference to the up-state performance of the phase shifter. The working principle of this push-pull-type DMTL phase shifter has been comprehensively worked out. A thorough detail of the design and performance analysis of the phase shifter has been carried out with various structural parameters using commercially available simulation tools with reference to a change in phase shift and has been verified using a system level simulation. The phase shifter is fabricated on the alumina substrate, using a suspended gold bridge membrane with a surface micromachining process. Asymmetric behaviour of push-pull bridge configuration has been noted and a corresponding effect on mechanical, electrical and RF performances has been extensively investigated. It is demonstrated 114° dB-1 FOM over 0-40 GHz band, which is the highest achievable FOM from a unit cell on an alumina substrate reported so far. A complete phase shifter contributes to a continuous differential phase shift of 0°-360° over 0-40 GHz band with a minimum actuation voltage of 8.1 V which is the highest achievable phase shift with the lowest actuation voltage as per till date on the alumina substrate with good repeatability and return loss better than 11.5 dB over 0-40 GHz band.

  11. Room Temperature Thin Film Ba(x)Sr(1-x)TiO3 Ku-Band Coupled MicrostripPhase Shifters: Effects of Film Thickness, Doping, Annealing and Substrate Choice

    NASA Technical Reports Server (NTRS)

    VanKeuls, F. W.; Mueller, C. H.; Miranda, F. A.; Romanofsky, R. R.; Canedy, C. L.; Aggarwal, S.; Venkatesan, T.; Ramesh, R.; Horwitz, S.; Chang, W.

    1999-01-01

    We report on measurements taken on over twenty Ku-band coupled microstrip phase shifters (CMPS) using thin ferroelectric films of Ba(x)Sr(1-x)TiO3. This CMPS design is a recent innovation designed to take advantage of the high tunability and tolerate the high dielectric constant of ferroelectric films at Ku- and K-band frequencies. These devices are envisioned as a component in low-cost steerable beam phased area antennas, Comparisons are made between devices with differing film thickness, annealed vs unannealed, Mn-doped vs. undoped, and also substrates of LaAlO3 and MgO. A comparison between the CMPS structure and a CPW phase shifter was also made oil the same ferroelectric film.

  12. Applications of Kinetic Inductance: Parametric Amplifier & Phase Shifter, 2DEG Coupled Co-planar Structures & Microstrip to Slotline Transition at RF Frequencies

    NASA Astrophysics Data System (ADS)

    Surdi, Harshad

    Kinetic inductance springs from the inertia of charged mobile carriers in alternating electric fields and it is fundamentally different from the magnetic inductance which is only a geometry dependent property. The magnetic inductance is proportional to the volume occupied by the electric and magnetic fields and is often limited by the number of turns of the coil. Kinetic inductance on the other hand is inversely proportional to the density of electrons or holes that exert inertia, the unit mass of the charge carriers and the momentum relaxation time of these charge carriers, all of which can be varied merely by modifying the material properties. Highly sensitive and broadband signal amplifiers often broaden the field of study in astrophysics. Quantum-noise limited travelling wave kinetic inductance parametric amplifiers offer a noise figure of around 0.5 K +/- 0.3 K as compared to 20 K in HEMT signal amplifiers and can be designed to operate to cover the entire W-band (75 GHz -- 115 GHz). The research cumulating to this thesis involves applying and exploiting kinetic inductance properties in designing a W-band orthogonal mode transducer, quadratic gain phase shifter with a gain of ~49 dB over a meter of microstrip transmission line. The phase shifter will help in measuring the maximum amount of phase shift Deltaφmax(I) that can be obtained from half a meter transmission line which helps in predicting the gain of a travelling wave parametric amplifier. In another project, a microstrip to slot line transition is designed and optimized to operate at 150 GHz and 220 GHz frequencies, that is used as a part of horn antenna coupled microwave kinetic inductance detector proposed to operate from 138 GHz to 250 GHz. In the final project, kinetic inductance in a 2D electron gas (2DEG) is explored by design, simulation, fabrication and experimentation. A transmission line model of a 2DEG proposed by Burke (1999), is simulated and verified experimentally by fabricating a

  13. Voltage and Level-Shifter Assignment Driven Floorplanning

    NASA Astrophysics Data System (ADS)

    Yu, Bei; Dong, Sheqin; Chen, Song; Goto, Satoshi

    Low Power Design has become a significant requirement when the CMOS technology entered the nanometer era. Multiple-Supply Voltage (MSV) is a popular and effective method for both dynamic and static power reduction while maintaining performance. Level shifters may cause area and Interconnect Length Overhead (ILO), and should be considered at both floorplanning and post-floorplanning stages. In this paper, we propose a two phases algorithm framework, called VLSAF, to solve voltage and level shifter assignment problem. At floorplanning phase, we use a convex cost network flow algorithm to assign voltage and a minimum cost flow algorithm to handle level-shifter assignment. At post-floorplanning phase, a heuristic method is adopted to redistribute white spaces and calculate the positions and shapes of level shifters. The experimental results show VLSAF is effective.

  14. Achromatic lattice comparison for light sources

    SciTech Connect

    Kramer, S.L.; Crosbie, E.A.; Cho, Y.

    1988-01-01

    The next generation of synchrotron light sources are being designed to support a large number of undulators and require long dispersion-free insertion regions. With less demand for radiation from the dipole magnets, the storage ring cost per undulator beam can be reduced by decreasing the number of dipole magnets and increasing the number of dispersion free straight sections. The two simplest achromatic lattices are the Chasman-Green or double-bend achromatic (DBA) and the three-bend achromat (TBA). The DBA in its simplest form consists of a single horizontally-focussing quadrupole between the two dipole magnets. Since this quadrupole strength is fixed by the achromatic condition, the natural emittance (/var epsilon//sub n/) may vary as the beta functions in the insertion region (IR) are varied. The expanded Chasman-Green (also DBA) uses multiple quadrupoles in the dispersive section to provide emittance control independent of the beta functions in the IR. Although this provides flexibility in the ID beta functions, the horizontal phase advance is constrained to /phi/ /approx equal/ 180/degree/ between approximately the centers of the dipole magnets. If small /var epsilon//sub n/ is required, the horizontal phase advance between the dipoles will be near one and the lattice properties will be dominated by this systematic resonance. The TBA lattice places a third dipole between the DBA dipoles, eliminating the 180/degree/ horizontal phase advance constraint. However, the requirement of small /var epsilon//sub n/ limits the range of tune, since /mu//sub x/ /approx equal/ 1.29 in the dipoles alone for /var epsilon//sub n/ near its minimum value. The minimum emittance is five times smaller for the TBA than for the DBA with the same number of periods and, therefore, its phase advance can be relaxed more than the DBA for the same natural emittance. 5 refs., 4 figs., 1 tab.

  15. Adjustable hybrid diffractive/refractive achromatic lens.

    PubMed

    Valley, Pouria; Savidis, Nickolaos; Schwiegerling, Jim; Dodge, Mohammad Reza; Peyman, Gholam; Peyghambarian, N

    2011-04-11

    We demonstrate a variable focal length achromatic lens that consists of a flat liquid crystal diffractive lens and a pressure-controlled fluidic refractive lens. The diffractive lens is composed of a flat binary Fresnel zone structure and a thin liquid crystal layer, producing high efficiency and millisecond switching times while applying a low ac voltage input. The focusing power of the diffractive lens is adjusted by electrically modifying the sub-zones and re-establishing phase wrapping points. The refractive lens includes a fluid chamber with a flat glass surface and an opposing elastic polydimethylsiloxane (PDMS) membrane surface. Inserting fluid volume through a pump system into the clear aperture region alters the membrane curvature and adjusts the refractive lens' focal position. Primary chromatic aberration is remarkably reduced through the coupling of the fluidic and diffractive lenses at selected focal lengths. Potential applications include miniature color imaging systems, medical and ophthalmic devices, or any design that utilizes variable focal length achromats.

  16. Full-range spectral domain optical coherence tomography using fiber-based sample scanner as self-phase shifter

    NASA Astrophysics Data System (ADS)

    Min, Eun Jung; Shin, Jun Geun; Lee, Jae Hwi; Lee, Byeong Ha

    2012-06-01

    We propose full-range spectral domain optical coherence tomography equipped with a fiber-based sample scanner, which is used for sample scanning and phase shifting for full-range image at the same time. For a fiber-based sample scanner, since the fiber tip oscillates as a free standing cantilever in general, unintentional phase shift occurs inevitably. The unintentional phase shift was used for eliminating the bothersome complex conjugate ghost image of OCT. In addition, fiber was tilted a few degree to give proper phase shift. In this scheme, moreover, image can be obtained without any physical modification of the scanner. To realize this technique, we constructed the SD-OCT system and fabricated a magnetically actuated single-body lensed fiber scanner due to advantages of simple design, low operating voltage, cost-effectiveness and low insertion loss. The scanner was made of lensed fiber loaded with an iron-based bead and a solenoid which is placed perpendicular to the lensed fiber. When a sinusoidal current is applied into the solenoid, the lensed fiber oscillated due to magnetic force between the iron-based bead and the solenoid. With the suggested full range method, we obtained contrast enhanced full-range SD OCT images of pearl and tooth. This simple and effective method can be applied to any fiber-based scanner and it has great potential as a handheld probe/endoscopic probe in biomedical imaging field.

  17. Achromatic Interaction Point Design

    SciTech Connect

    Guimei Wang,, Yaroslav Derbenev, S.Alex Bogacz, P. Chevtsov, Andre Afanaciev, Charles Ankenbrandt, Valentin Ivanov, Rolland P. Johnson

    2009-05-01

    Designers of high-luminosity energy-frontier muon colliders must provide strong beam focusing in the interaction regions. However, the construction of a strong, aberration-free beam focus is difficult and space consuming, and long straight sections generate an off-site radiation problem due to muon decay neutrinos that interact as they leave the surface of the earth. Without some way to mitigate the neutrino radiation problem, the maximum c.m. energy of a muon collider will be limited to about 3.5 TeV. A new concept for achromatic low beta design is being developed, in which the interaction region telescope and optical correction elements, are installed in the bending arcs. The concept, formulated analytically, combines space economy, a preventative approach to compensation for aberrations, and a reduction of neutrino flux concentration. An analytical theory for the aberration-free, low beta, spatially compact insertion is being developed.

  18. Simultaneous second- and third- order spectral phase control of Ti:sapphire laser pulses using achromatic doublet prisms.

    PubMed

    Mueller, Alexander; Fuerbach, Alexander

    2016-03-20

    The standard technique commonly utilized to introduce large amounts of negative group delay dispersion (GDD) into the beam path of ultrashort laser pulses with low insertion losses is the use of a pair of prisms in a double pass configuration. However, one disadvantage of this approach is the unavoidable introduction of additional high-order spectral phase errors, most notably third-order dispersion (TOD) due to the characteristics of the refractive index of available optical materials. In this paper we provide an overview of the dispersive properties of more than 100 common types of optical glasses, used either as a bulk stretcher or in a prism compressor configuration. In addition, we present a novel method that enables independent control of GDD and TOD in a prism-only setup. The performance of different prism combinations is analyzed numerically, and design guidelines are given. PMID:27140563

  19. Simultaneous second- and third- order spectral phase control of Ti:sapphire laser pulses using achromatic doublet prisms.

    PubMed

    Mueller, Alexander; Fuerbach, Alexander

    2016-03-20

    The standard technique commonly utilized to introduce large amounts of negative group delay dispersion (GDD) into the beam path of ultrashort laser pulses with low insertion losses is the use of a pair of prisms in a double pass configuration. However, one disadvantage of this approach is the unavoidable introduction of additional high-order spectral phase errors, most notably third-order dispersion (TOD) due to the characteristics of the refractive index of available optical materials. In this paper we provide an overview of the dispersive properties of more than 100 common types of optical glasses, used either as a bulk stretcher or in a prism compressor configuration. In addition, we present a novel method that enables independent control of GDD and TOD in a prism-only setup. The performance of different prism combinations is analyzed numerically, and design guidelines are given.

  20. Achromatic beam transport of High Current Injector

    NASA Astrophysics Data System (ADS)

    Kumar, Sarvesh; Mandal, A.

    2016-02-01

    The high current injector (HCI) provides intense ion beams of high charge state using a high temperature superconducting ECR ion source. The ion beam is accelerated upto a final energy of 1.8 MeV/u due to an electrostatic potential, a radio frequency quadrupole (RFQ) and a drift tube linac (DTL). The ion beam has to be transported to superconducting LINAC which is around 50 m away from DTL. This section is termed as high energy beam transport section (HEBT) and is used to match the beam both in transverse and longitudinal phase space to the entrance of LINAC. The HEBT section is made up of four 90 deg. achromatic bends and interconnecting magnetic quadrupole triplets. Two RF bunchers have been used for longitudinal phase matching to the LINAC. The ion optical design of HEBT section has been simulated using different beam dynamics codes like TRACEWIN, GICOSY and TRACE 3D. The field computation code OPERA 3D has been utilized for hardware design of all the magnets. All the dipole and quadrupole magnets have been field mapped and their test results such as edge angles measurements, homogeneity and harmonic analysis etc. are reported. The whole design of HEBT section has been performed such that the most of the beam optical components share same hardware design and there is ample space for beam diagnostics as per geometry of the building. Many combination of achromatic bends have been simulated to transport the beam in HEBT section but finally the four 90 deg. achromatic bend configuration is found to be the best satisfying all the geometrical constraints with simplified beam tuning process in real time.

  1. Achromatic doublets for Gaussian beams

    NASA Astrophysics Data System (ADS)

    Biraud, F.; Daigne, G.

    1991-04-01

    The properties of doublets of thin lenses in the Gaussian optics approximation were investigated. Two different ways for such a doublet to give strictly achromatic images of the input beam waist were found. Both solutions may be useful in a variety of applications, one being the possibility of shaping asymmetrical beams for fan beam antennas illumination. Using modes higher than the fundamental mode will allow the design of more realistic focal systems.

  2. Achromatic and uncoupled medical gantry

    DOEpatents

    Tsoupas, Nicholaos; Kayran, Dmitry; Litvinenko, Vladimir; MacKay, William W.

    2011-11-22

    A medical gantry that focus the beam from the beginning of the gantry to the exit of the gantry independent of the rotation angle of the gantry by keeping the beam achromatic and uncoupled, thus, avoiding the use of collimators or rotators, or additional equipment to control the beam divergence, which may cause beam intensity loss or additional time in irradiation of the patient, or disadvantageously increase the overall gantry size inapplicable for the use in the medical treatment facility.

  3. Achromatic Metasurface Lens at Telecommunication Wavelengths.

    PubMed

    Khorasaninejad, Mohammadreza; Aieta, Francesco; Kanhaiya, Pritpal; Kats, Mikhail A; Genevet, Patrice; Rousso, David; Capasso, Federico

    2015-08-12

    Nanoscale optical resonators enable a new class of flat optical components called metasurfaces. This approach has been used to demonstrate functionalities such as focusing free of monochromatic aberrations (i.e., spherical and coma), anomalous reflection, and large circular dichroism. Recently, dielectric metasurfaces that compensate the phase dispersion responsible for chromatic aberrations have been demonstrated. Here, we utilize an aperiodic array of coupled dielectric nanoresonators to demonstrate a multiwavelength achromatic lens. The focal length remains unchanged for three wavelengths in the near-infrared region (1300, 1550, and 1800 nm). Experimental results are in agreement with full-wave simulations. Our findings are an essential step toward a realization of broadband flat optical elements.

  4. Effects of shifter edge topography on through focus performance

    NASA Astrophysics Data System (ADS)

    Hotta, Shoji; Pistor, Thomas V.; Adam, Konstantinos; Neureuther, Andrew R.

    2001-01-01

    We have investigated the effects of the topography of the phase-shifting mask on the aerial image characteristics in DUV lithography. The calculation of near fields is carried out through simulation of the mask with TEMPEST and linking the resultant near fields to EM-Aerial for imaging. It is shown that the Fourier spectrum for an alternating phase-shifting mask can be decomposed into Fourier spectra for single openings. The amplitude and phase of the diffraction orders for the single opening are utilized for the systematic analysis of the shifter edge topography. The analysis framework developed in this paper clearly identifies the effects of the wall of the phase shifter, the residual transmittance through the chromium area, and the cross-talk between adjacent features. This analysis framework also allows these effects be merged in design. The near field profile in the vicinity of the shifter wall is also investigated for different feature sizes, and the optimum design for different feature sizes is discussed. The effect of the wall angle profile is shown to be acceptable.

  5. Simultaneous contrast and gamut relativity in achromatic color perception.

    PubMed

    Vladusich, Tony

    2012-09-15

    Simultaneous contrast refers to the respective whitening or blackening of physically identical image regions surrounded by regions of low or high luminance, respectively. A common method of measuring the strength of this effect is achromatic color matching, in which subjects adjust the luminance of a target region to achieve an achromatic color match with another region. Here I present psychophysical data questioning the assumption--built into many models of achromatic color perception--that achromatic colors are represented as points in a one-dimensional (1D) perceptual space, or an absolute achromatic color gamut. I present an alternative model in which the achromatic color gamut corresponding to a target region is defined relatively, with respect to surround luminance. Different achromatic color gamuts in this model correspond to different 1D lines through a 2D perceptual space composed of blackness and whiteness dimensions. Each such line represents a unique gamut of achromatic colors ranging from black to white. I term this concept gamut relativity. Achromatic color matches made between targets surrounded by regions of different luminance are shown to reflect the relative perceptual distances between points lying on different gamut lines. The model suggests a novel geometrical approach to simultaneous contrast and achromatic color matching in terms of the vector summation of local luminance and contrast components, and sets the stage for a unified computational theory of achromatic color perception.

  6. Achromatized endomicroscope objective for optical biopsy

    PubMed Central

    Kyrish, Matthew; Tkaczyk, Tomasz S.

    2013-01-01

    Currently, researchers and clinicians lack achromatized endomicroscope objectives that are as narrow as biopsy needles. We present a proof-of-concept prototype that validates the optical design of an NA0.4 objective. The objective, built with plastic lenses, has a 0.9 mm clear aperture and is achromatized from 452 nm to 623 nm. The objective’s measured Strehl ratio is 0.74 ± 0.05 across a 250 μm FOV. We perform optical sectioning via structured illumination through the objective while capturing fluorescence images of breast carcinoma cells stained with proflavine and cresyl violet. This technology has the potential to improve optical biopsies and provide the next step forward in cancer diagnostics. PMID:23412009

  7. Achromatic synesthesias - a functional magnetic resonance imaging study.

    PubMed

    Melero, H; Ríos-Lago, M; Peña-Melián, A; Álvarez-Linera, J

    2014-09-01

    Grapheme-color synesthetes experience consistent, automatic and idiosyncratic colors associated with specific letters and numbers. Frequently, these specific associations exhibit achromatic synesthetic qualities (e.g. white, black or gray). In this study, we have investigated for the first time the neural basis of achromatic synesthesias, their relationship to chromatic synesthesias and the achromatic congruency effect in order to understand not only synesthetic color but also other components of the synesthetic experience. To achieve this aim, functional magnetic resonance imaging experiments were performed in a group of associator grapheme-color synesthetes and matched controls who were stimulated with real chromatic and achromatic stimuli (Mondrians), and with letters and numbers that elicited different types of grapheme-color synesthesias (i.e. chromatic and achromatic inducers which elicited chromatic but also achromatic synesthesias, as well as congruent and incongruent ones). The information derived from the analysis of Mondrians and chromatic/achromatic synesthesias suggests that real and synesthetic colors/achromaticity do not fully share neural mechanisms. The whole-brain analysis of BOLD signals in response to the complete set of synesthetic inducers revealed that the functional peculiarities of the synesthetic brain are distributed, and reflect different components of the synesthetic experience: a perceptual component, an (attentional) feature binding component, and an emotional component. Additionally, the inclusion of achromatic experiences has provided new evidence in favor of the emotional binding theory, a line of interpretation which constitutes a bridge between grapheme-color synesthesia and other developmental modalities of the phenomenon.

  8. Achromatic synesthesias - a functional magnetic resonance imaging study.

    PubMed

    Melero, H; Ríos-Lago, M; Peña-Melián, A; Álvarez-Linera, J

    2014-09-01

    Grapheme-color synesthetes experience consistent, automatic and idiosyncratic colors associated with specific letters and numbers. Frequently, these specific associations exhibit achromatic synesthetic qualities (e.g. white, black or gray). In this study, we have investigated for the first time the neural basis of achromatic synesthesias, their relationship to chromatic synesthesias and the achromatic congruency effect in order to understand not only synesthetic color but also other components of the synesthetic experience. To achieve this aim, functional magnetic resonance imaging experiments were performed in a group of associator grapheme-color synesthetes and matched controls who were stimulated with real chromatic and achromatic stimuli (Mondrians), and with letters and numbers that elicited different types of grapheme-color synesthesias (i.e. chromatic and achromatic inducers which elicited chromatic but also achromatic synesthesias, as well as congruent and incongruent ones). The information derived from the analysis of Mondrians and chromatic/achromatic synesthesias suggests that real and synesthetic colors/achromaticity do not fully share neural mechanisms. The whole-brain analysis of BOLD signals in response to the complete set of synesthetic inducers revealed that the functional peculiarities of the synesthetic brain are distributed, and reflect different components of the synesthetic experience: a perceptual component, an (attentional) feature binding component, and an emotional component. Additionally, the inclusion of achromatic experiences has provided new evidence in favor of the emotional binding theory, a line of interpretation which constitutes a bridge between grapheme-color synesthesia and other developmental modalities of the phenomenon. PMID:24845620

  9. Visible-Frequency Dielectric Metasurfaces for Multiwavelength Achromatic and Highly Dispersive Holograms.

    PubMed

    Wang, Bo; Dong, Fengliang; Li, Qi-Tong; Yang, Dong; Sun, Chengwei; Chen, Jianjun; Song, Zhiwei; Xu, Lihua; Chu, Weiguo; Xiao, Yun-Feng; Gong, Qihuang; Li, Yan

    2016-08-10

    Dielectric metasurfaces built up with nanostructures of high refractive index represent a powerful platform for highly efficient flat optical devices due to their easy-tuning electromagnetic scattering properties and relatively high transmission efficiencies. Here we show visible-frequency silicon metasurfaces formed by three kinds of nanoblocks multiplexed in a subwavelength unit to constitute a metamolecule, which are capable of wavefront manipulation for red, green, and blue light simultaneously. Full phase control is achieved for each wavelength by independently changing the in-plane orientations of the corresponding nanoblocks to induce the required geometric phases. Achromatic and highly dispersive meta-holograms are fabricated to demonstrate the wavefront manipulation with high resolution. This technique could be viable for various practical holographic applications and flat achromatic devices. PMID:27398793

  10. Passive, achromatic, nearly isochronous bending system

    DOEpatents

    Douglas, David R.; Yunn, Byung C.

    2004-05-18

    A particle beam bending system having a geometry that applies active bending only beyond the chord of the orbit for any momentum component. Using this bending configuration, all momentum components emerge dispersed in position only; all trajectories are parallel by construction. Combining a pair of such bends with reflective symmetry produces a bend cell that is, by construction, achromatic to all orders. By the particular choice of 45.degree. individual bends, a pair of such achromats can be used as the basis of a 180.degree. recirculation arc. Other rational fractions of a full 180.degree. bend serve equally well (e.g., 2 bends/cell.times.90.degree./bend.times.1 cell /arc; 2 bends/cell.times.30.degree./bend.times.3 cells/arc, etc), as do combinations of multiple bending numerologies (e.g., 2 bends/cell.times.22.5.degree./bend.times.2 cells+2 bends/cell.times.45.degree./bend.times.1 cell). By the choice of entry pole face rotation of the first magnet and exit pole face rotation of the second magnet (with a value to be determined from the particular beam stability requirements imposed by the choice of bending angle and beam properties to be used in any particular application), desirable focusing properties can be introduced and beam stability can be insured.

  11. ACHRO: A program to help design achromatic bends

    SciTech Connect

    Rusthoi, D.

    1993-03-01

    ACHRO is a very simple 2000-line. FORTRAN code that provides help for the designer of the achromatic bend. Given a beam momentum, the program calculates the required drift lengths and dipole parameters which it will apply to any one of several different types of achromats. The types of achromats that the code helps to design include the Enge dual-270,`` the Brown 2-dipole, the Leboutet 3-dipole, and the Enge 4-dipole, as well as the periodic systems which can be designed to any order in symmetric, nonsymmetric and stair-step varieties. Given the dimensions into which a bend must fit, ACHRO will calculate the geometrical parameters in an X-Y plane for a single or multiple achromat, and for achromatic ``S-bend`` configurations where possible. ACHRO makes it very easy to optimize a bend with respect to drift lengths and magnet parameters by allowing the user to change parameter values and see the resulting calculation. Used in conjunction with a beam-transport code, ACHRO makes it possible for a designer to consider various types of achromatic bends in the same beamline layout in order to compare important bend characteristics such as dispersion, Isochronicity, sensitivity, geometric and chromatic aberrations, aperture requirements, space for diagnostics, etc., all of which are largely a function of the geometry and the type of achromat selected.

  12. ACHRO: A program to help design achromatic bends

    SciTech Connect

    Rusthoi, D.

    1993-01-01

    ACHRO is a very simple 2000-line. FORTRAN code that provides help for the designer of the achromatic bend. Given a beam momentum, the program calculates the required drift lengths and dipole parameters which it will apply to any one of several different types of achromats. The types of achromats that the code helps to design include the Enge dual-270,'' the Brown 2-dipole, the Leboutet 3-dipole, and the Enge 4-dipole, as well as the periodic systems which can be designed to any order in symmetric, nonsymmetric and stair-step varieties. Given the dimensions into which a bend must fit, ACHRO will calculate the geometrical parameters in an X-Y plane for a single or multiple achromat, and for achromatic S-bend'' configurations where possible. ACHRO makes it very easy to optimize a bend with respect to drift lengths and magnet parameters by allowing the user to change parameter values and see the resulting calculation. Used in conjunction with a beam-transport code, ACHRO makes it possible for a designer to consider various types of achromatic bends in the same beamline layout in order to compare important bend characteristics such as dispersion, Isochronicity, sensitivity, geometric and chromatic aberrations, aperture requirements, space for diagnostics, etc., all of which are largely a function of the geometry and the type of achromat selected.

  13. Performance of an Achromatic Focal Plane Mask for Exoplanet Imaging Coronagraphy

    NASA Technical Reports Server (NTRS)

    Newman, Kevin; Belikov, Ruslan; Pluzhnik, Eugene; Balasubramanian, Kunjithapatham; Wilson, Dan

    2014-01-01

    Coronagraph technology combined with wavefront control is close to achieving the contrast and inner working angle requirements in the lab necessary to observe the faint signal of an Earth-like exoplanet in monochromatic light. An important remaining technological challenge is to achieve high contrast in broadband light. Coronagraph bandwidth is largely limited by chromaticity of the focal plane mask, which is responsible for blocking the stellar PSF. The size of a stellar PSF scales linearly with wavelength; ideally, the size of the focal plane mask would also scale with wavelength. A conventional hard-edge focal plane mask has a fixed size, normally sized for the longest wavelength in the observational band to avoid starlight leakage. The conventional mask is oversized for shorter wavelengths and blocks useful discovery space. Recently we presented a solution to the size chromaticity challenge with a focal plane mask designed to scale its effective size with wavelength. In this paper, we analyze performance of the achromatic size-scaling focal plane mask within a Phase Induced Amplitude Apodization (PIAA) coronagraph. We present results from wavefront control around the achromatic focal plane mask, and demonstrate the size-scaling effect of the mask with wavelength. The edge of the dark zone, and therefore the inner working angle of the coronagraph, scale with wavelength. The achromatic mask enables operation in a wider band of wavelengths compared with a conventional hard-edge occulter.

  14. An achromat for the ANU 14UD linac

    NASA Astrophysics Data System (ADS)

    MacKinnon, B. A.; Stuchbery, A. E.; Weisser, D. C.

    1994-06-01

    A compact magnetic achromat has been designed and constructed to deliver the horizontal output beam of the ANU 14UD Pelletron tandem accelerator to a superconducting booster accelerator to be located in part of the experimental hall of the laboratory. The achromat provides 90° deflection of the ion beam and is fully achromatic with respect to energy spread in the beam. Due to space constraints in the laboratory, it has been necessary to locate the beam chopping device and bunching cryostat upstream of the 90° bend, thereby requiring that the beam trajectory following the bend be independent of beam energy. The optical performance of the achromat has been investigated in first order using the matrix transfer beam calculation code TRANSPORT, and in high order using the particle tracking code RAYTRACE. In first order, the achromat is shown to have precise achromatism and to be isochronous with the exception of small and predictable time waist shifts. High order calculations lead to an expectation of less than 6% worsening of the transverse beam emittance and less than 9 ps timing degradation for 170 MeV 59Ni 13+, an isotope of interest in accelerator mass spectrometry. The effect on the transmission of this isotope through the subsequent acceleration stages and beam-optical elements is negligible.

  15. The achromatic locus: effect of navigation direction in color space.

    PubMed

    Chauhan, Tushar; Perales, Esther; Xiao, Kaida; Hird, Emily; Karatzas, Dimosthenis; Wuerger, Sophie

    2014-01-24

    An achromatic stimulus is defined as a patch of light that is devoid of any hue. This is usually achieved by asking observers to adjust the stimulus such that it looks neither red nor green and at the same time neither yellow nor blue. Despite the theoretical and practical importance of the achromatic locus, little is known about the variability in these settings. The main purpose of the current study was to evaluate whether achromatic settings were dependent on the task of the observers, namely the navigation direction in color space. Observers could either adjust the test patch along the two chromatic axes in the CIE u*v* diagram or, alternatively, navigate along the unique-hue lines. Our main result is that the navigation method affects the reliability of these achromatic settings. Observers are able to make more reliable achromatic settings when adjusting the test patch along the directions defined by the four unique hues as opposed to navigating along the main axes in the commonly used CIE u*v* chromaticity plane. This result holds across different ambient viewing conditions (Dark, Daylight, Cool White Fluorescent) and different test luminance levels (5, 20, and 50 cd/m(2)). The reduced variability in the achromatic settings is consistent with the idea that internal color representations are more aligned with the unique-hue lines than the u* and v* axes.

  16. Achromatic Focal Plane Mask for Exoplanet Imaging Coronagraphy

    NASA Technical Reports Server (NTRS)

    Newman, Kevin Edward; Belikov, Ruslan; Guyon, Olivier; Balasubramanian, Kunjithapatham; Wilson, Dan

    2013-01-01

    Recent advances in coronagraph technologies for exoplanet imaging have achieved contrasts close to 1e10 at 4 lambda/D and 1e-9 at 2 lambda/D in monochromatic light. A remaining technological challenge is to achieve high contrast in broadband light; a challenge that is largely limited by chromaticity of the focal plane mask. The size of a star image scales linearly with wavelength. Focal plane masks are typically the same size at all wavelengths, and must be sized for the longest wavelength in the observational band to avoid starlight leakage. However, this oversized mask blocks useful discovery space from the shorter wavelengths. We present here the design, development, and testing of an achromatic focal plane mask based on the concept of optical filtering by a diffractive optical element (DOE). The mask consists of an array of DOE cells, the combination of which functions as a wavelength filter with any desired amplitude and phase transmission. The effective size of the mask scales nearly linearly with wavelength, and allows significant improvement in the inner working angle of the coronagraph at shorter wavelengths. The design is applicable to almost any coronagraph configuration, and enables operation in a wider band of wavelengths than would otherwise be possible. We include initial results from a laboratory demonstration of the mask with the Phase Induced Amplitude Apodization coronagraph.

  17. Dielectric resonators in phase-control devices

    NASA Astrophysics Data System (ADS)

    Bezborodov, Iu. M.; Loskutov, V. Iu.; Savel'Ev, A. V.

    1987-07-01

    The paper describes the design and analysis of dielectric-resonator microwave phase-shifters with good electrical properties and weight/size parameters. A reflection-type phase-shifter with a dielectric resonator has been constructed for an active phased array; the phase-shifter provides for both discrete and continuous changes of phase from 0 to 360 deg; the direct phase-shifter loss amounts to 0.5 dB. It is concluded that the proposed device can successfully compete with integrated p-i-n and semiconductor diode devices.

  18. Achromatic lens systems for near infrared instruments.

    NASA Astrophysics Data System (ADS)

    Oliva, E.; Gennari, S.

    1995-11-01

    The chromatic characteristics of glasses transmitting in the near infrared (λ<=2.5μm) are analyzed. Achromatic systems with superb characteristics can be obtained by coupling the crystals BaF_2_, SrF_2_ and CaF_2_ with the IR Schott glasses irg2, irg3 and irg7, respectively. The best performances are obtained using BaF_2_-irg2 and SrF_2_- irg3 while CaF_2_-irg7 is worse (due to the lower Abbe number of CaF_2_) but significantly better than other pairs normally used in IR astronomical instrumentation. Use of these combinations could much simplify the design of astronomical focal plane instruments. Measurements of the refraction index of the IR glasses at cryogenic temperatures are however necessary. As a practical application we present the preliminary design of a F/11-F/4.3 focal reducer for the Italian 3.5 m Galileo telescope. The system employs 6 spherical lenses and its image quality matches the requirements of a 1024^2^ array with 18.5μm pixels in both the imaging and spectroscopic (with grism) modes.

  19. The spatial tuning of achromatic and chromatic vision in budgerigars.

    PubMed

    Lind, Olle; Kelber, Almut

    2011-01-01

    Birds are assumed to use half of their cones (double cones) to detect fine spatial detail while their other half (single cones) is used for color vision. However, the spatial resolution of the color pathway in birds has never been studied. We determined the spatial contrast sensitivity to achromatic and isoluminant red-green and blue-green color gratings in budgerigars (Melopsittacus undulatus). Contrast sensitivity to achromatic gratings has band-pass characteristics while that for red-green and blue-green gratings has low-pass properties. Maximum sensitivity is lower to blue-green than to red-green gratings and the acuity for both color gratings is less than half (ca. 4.5 cycles/degree) of that for achromatic gratings (ca. 10 cycles/degree). This suggests that achromatic vision in birds, as in humans and bees, is tuned for detecting fine detail while chromatic vision is tuned for viewing larger fields. Similar to humans, blue-sensitive cones contribute little to spatial vision. Moreover, budgerigars detected gratings having both achromatic and chromatic contrasts more reliably at high spatial frequencies than gratings with either of these contrasts, suggesting that the single and double cone pathways are incompletely separated. The study demonstrates the importance of the spatial dimension of color vision; fine patterns remain unresolved even if they present large color contrasts. PMID:21636524

  20. Lightness dependence of achromatic loci in color-appearance coordinates

    PubMed Central

    Kuriki, Ichiro

    2015-01-01

    Shifts in the appearance of color under different illuminant chromaticity are known to be incomplete, and fit nicely with a simple linear transformation of cone responses that aligns the achromatic points under two illuminants. Most chromaticity-transfer functions with von-Kries-like transformations use only one set of values to fit the color shifts from one illuminant to another. However, an achromatic point shifts its chromaticity depending on the lightness of the test stimulus. This lightness dependence of the achromatic-point locus is qualitatively similar to a phenomenon known as the Helson-Judd effect. The present study suggests that the lightness dependency of achromatic points appears to be a general trend, which is supported by the results from deriving the optimal von-Kries coefficients for different lightness levels that best fit the color shifts under a different illuminant chromaticity. Further, we report that such a lightness dependence of the achromatic-point loci can be represented simply as a straight line in coordinates defined using color-appearance models such as CIECAM when normalized for daylight. PMID:25713543

  1. Optical properties of new wide heterogeneous waveguides with thermo optical shifters.

    PubMed

    De Leonardis, Francesco; Tsarev, Andrei V; Passaro, Vittorio M

    2008-12-22

    We present analysis and simulation of novel silicon-on-insulator (SOI) heterogeneous waveguides with thermo-optic phase shifters. New structure design contains a p-n junction on both sides of SOI ridge waveguide with 220 nm x 35 microm silicon core. Strongly mode-dependent optical losses (by additional free charge absorption) provide quasi-singe-mode behavior of wide waveguide with mode size approximately 10 microm. Local heater produces an efficient phase shifting by small temperature increase (DeltaT approximately 2K), switching power (< 40 mW) and switching time (< 10 micros). Mode optical losses are significantly decreased at high heating (DeltaT approximately 120 K).

  2. Anisotropic meta-mirror for achromatic electromagnetic polarization manipulation

    NASA Astrophysics Data System (ADS)

    Pu, Mingbo; Chen, Po; Wang, Yanqin; Zhao, Zeyu; Huang, Cheng; Wang, Changtao; Ma, Xiaoliang; Luo, Xiangang

    2013-04-01

    Polarization states are of particular importance for the manipulation of electromagnetic waves. Here, we proposed the design and experimental demonstration of anisotropic meta-mirror for achromatic polarization tuning. It is demonstrated that linear polarized wave can be achromatically transformed to its cross-polarization state or to arbitrary circular polarization after its reflection from the mirror. Microwave experiments verified that the fraction bandwidth for 90% transformation efficiency can be larger than 3:1. Furthermore, by utilizing photoinduced carrier generation in silicon, a broadband tunable circular polarizer is demonstrated in the terahertz regime.

  3. Nonimaging achromatic shaped Fresnel lenses for ultrahigh solar concentration.

    PubMed

    Languy, Fabian; Habraken, Serge

    2013-05-15

    The maximum concentration ratio achievable with a solar concentrator made of a single refractive primary optics is much more limited by the chromatic aberration than by any other aberration. Therefore achromatic doublets made with poly(methyl methacrylate) and polycarbonate are of great interest to enhance the concentration ratio and to achieve a spectrally uniform flux on the receiver. In this Letter, shaped achromatic Fresnel lenses are investigated. One lossless design is of high interest since it provides spectrally and spatially uniform flux without being affected by soiling problems. With this design an optical concentration ratio of about 8500× can be achieved. PMID:23938926

  4. An Investigation of the Eighteenth-Century Achromatic Telescope

    ERIC Educational Resources Information Center

    Jaecks, Duane H.

    2010-01-01

    The optical quality and properties of over 200 telescopes residing in museums and private collections have been measured and tested with the goal of obtaining new information about the early development of the achromatic lens (1757-1770). Quantitative measurements of the chromatic and spherical aberration of telescope objective lenses were made…

  5. Suppression of the emittance growth induced by coherent synchrotron radiation in triple-bend achromats

    NASA Astrophysics Data System (ADS)

    Huang, Xi-Yang; Jiao, Yi; Xu, Gang; Cui, Xiao-Hao

    2015-05-01

    The coherent synchrotron radiation (CSR) effect in a bending path plays an important role in transverse emittance dilution in high-brightness light sources and linear colliders, where the electron beams are of short bunch length and high peak current. Suppression of the emittance growth induced by CSR is critical to preserve the beam quality and help improve the machine performance. It has been shown that the CSR effect in a double-bend achromat (DBA) can be analyzed with the two-dimensional point-kick analysis method. In this paper, this method is applied to analyze the CSR effect in a triple-bend achromat (TBA) with symmetric layout, which is commonly used in the optics designs of energy recovery linacs (ERLs). A condition of cancelling the CSR linear effect in such a TBA is obtained, and is verified through numerical simulations. It is demonstrated that emittance preservation can be achieved with this condition, and to a large extent, has a high tolerance to the fluctuation of the initial transverse phase space distribution of the beam. Supported by National Natural Science Foundation of China (11475202, 11405187) and Youth Innovation Promotion Association of Chinese Academy of Sciences (2015009)

  6. Optimized achromatic phase-matching system and method

    DOEpatents

    Trebino, R.; DeLong, K.; Hayden, C.

    1997-07-15

    An optical system for efficiently directing a large bandwidth light (e.g., a femtosecond laser pulse) onto a nonlinear optical medium includes a plurality of optical elements for directing an input light pulse onto a nonlinear optical medium arranged such that the angle {theta}{sub in} which the light pulse directed onto the nonlinear optical medium is substantially independent of a position x of the light beam entering the optical system. The optical system is also constructed such that the group velocity dispersion of light pulses passing through the system can be tuned to a desired value including negative group velocity dispersion. 15 figs.

  7. Optimized achromatic phase-matching system and method

    DOEpatents

    Trebino, Rick; DeLong, Ken; Hayden, Carl

    1997-01-01

    An optical system for efficiently directing a large bandwidth light (e.g., a femtosecond laser pulse) onto a nonlinear optical medium includes a plurality of optical elements for directing an input light pulse onto a nonlinear optical medium arranged such that the angle .theta..sub.in which the light pulse directed onto the nonlinear optical medium is substantially independent of a position x of the light beam entering the optical system. The optical system is also constructed such that the group velocity dispersion of light pulses passing through the system can be tuned to a desired value including negative group velocity dispersion.

  8. Optical properties of new wide heterogeneous waveguides with thermo optical shifters.

    PubMed

    De Leonardis, Francesco; Tsarev, Andrei V; Passaro, Vittorio M

    2008-12-22

    We present analysis and simulation of novel silicon-on-insulator (SOI) heterogeneous waveguides with thermo-optic phase shifters. New structure design contains a p-n junction on both sides of SOI ridge waveguide with 220 nm x 35 microm silicon core. Strongly mode-dependent optical losses (by additional free charge absorption) provide quasi-singe-mode behavior of wide waveguide with mode size approximately 10 microm. Local heater produces an efficient phase shifting by small temperature increase (DeltaT approximately 2K), switching power (< 40 mW) and switching time (< 10 micros). Mode optical losses are significantly decreased at high heating (DeltaT approximately 120 K). PMID:19104563

  9. Achromatic half-wave plate for submillimeter instruments in cosmic microwave background astronomy: experimental characterization.

    PubMed

    Pisano, Giampaolo; Savini, Giorgio; Ade, Peter A R; Haynes, Vic; Gear, Walter K

    2006-09-20

    An achromatic half-wave plate (HWP) to be used in millimeter cosmic microwave background (CMB) polarization experiments has been designed, manufactured, and tested. The design is based on the 5-plates Pancharatnam recipe and it works in the frequency range 85-185 GHz. A model has been used to predict the transmission, reflection, absorption, and phase shift as a function of frequency. The HWP has been tested by using coherent radiation from a back-wave oscillator to investigate its modulation efficiency and with incoherent radiation from a polarizing Fourier transform spectrometer (FTS) to explore its frequency behavior. The FTS measurements have been fitted with an optical performance model which is in excellent agreement with the data. A detailed analysis of the data also allows a precise determination of the HWP fast and slow axes in the frequency band of operation. A list of the HWP performance characteristics is reported including estimates of its cross polarization.

  10. Fabrication of Achromatic Infrared Wave Plate by Direct Imprinting Process on Chalcogenide Glass

    NASA Astrophysics Data System (ADS)

    Yamada, Itsunari; Yamashita, Naoto; Tani, Kunihiko; Einishi, Toshihiko; Saito, Mitsunori; Fukumi, Kouhei; Nishii, Junji

    2012-07-01

    An achromatic infrared wave plate was fabricated by forming a subwavelength grating on the chalcogenide glass using direct imprint lithography. A low toxic chalcogenide glass (Sb-Ge-Sn-S system) substrate was imprinted with a grating of 1.63-µm depth, a fill factor of 0.7, and 3-µm period using glassy carbon as a mold at 253 °C and 3.8 MPa. Phase retardation of the element reached around 30° at 8.5-10.5 µm wavelengths, and the transmittance exceeded that of a flat substrate over 8 µm wavelength. Fabrication of the mid-infrared wave plate is thereby less expensive than that of conventional crystalline wave plates.

  11. Polypropylene embedded metal mesh broadband achromatic half-wave plate for millimeter wavelengths.

    PubMed

    Zhang, Jin; Ade, Peter A R; Mauskopf, Philip; Savini, Giorgio; Moncelsi, Lorenzo; Whitehouse, Nicola

    2011-07-20

    We describe a novel multilayered metal-mesh achromatic half-wave plate (HWP) for use in astronomical polarimetric instruments. The HWP is designed to operate across the frequency range from 125 to 250 GHz. The wave plate is manufactured from 12 layers of thin film metallic inductive and capacitive grids patterned onto polypropylene sheets, which are then bonded together using a hot-pressing technique. Transmission line modeling and three-dimensional electromagnetic simulations are used to optimize the parameters of the metal-mesh patterns and to evaluate their optical properties. A prototype HWP has been fabricated, and its performance is characterized in a polarizing Fourier transform spectrometer. The device performance is consistent with the modeling, although the measured differential phase shift for two orthogonal polarizations is lower than expected. This difference is likely to result from imperfect patterning of individual layers and misalignment of the grids during manufacture. PMID:21772356

  12. Visible-infrared achromatic imaging by wavefront coding with wide-angle automobile camera

    NASA Astrophysics Data System (ADS)

    Ohta, Mitsuhiko; Sakita, Koichi; Shimano, Takeshi; Sugiyama, Takashi; Shibasaki, Susumu

    2016-09-01

    We perform an experiment of achromatic imaging with wavefront coding (WFC) using a wide-angle automobile lens. Our original annular phase mask for WFC was inserted to the lens, for which the difference between the focal positions at 400 nm and at 950 nm is 0.10 mm. We acquired images of objects using a WFC camera with this lens under the conditions of visible and infrared light. As a result, the effect of the removal of the chromatic aberration of the WFC system was successfully determined. Moreover, we fabricated a demonstration set assuming the use of a night vision camera in an automobile and showed the effect of the WFC system.

  13. Visible–infrared achromatic imaging by wavefront coding with wide-angle automobile camera

    NASA Astrophysics Data System (ADS)

    Ohta, Mitsuhiko; Sakita, Koichi; Shimano, Takeshi; Sugiyama, Takashi; Shibasaki, Susumu

    2016-09-01

    We perform an experiment of achromatic imaging with wavefront coding (WFC) using a wide-angle automobile lens. Our original annular phase mask for WFC was inserted to the lens, for which the difference between the focal positions at 400 nm and at 950 nm is 0.10 mm. We acquired images of objects using a WFC camera with this lens under the conditions of visible and infrared light. As a result, the effect of the removal of the chromatic aberration of the WFC system was successfully determined. Moreover, we fabricated a demonstration set assuming the use of a night vision camera in an automobile and showed the effect of the WFC system.

  14. Achromatically injection-seeded terahertz-wave parametric generator.

    PubMed

    Imai, Kazuhiro; Kawase, Kodo; Minamide, Hiroaki; Ito, Hiromasa

    2002-12-15

    An achromatically injection-seeded terahertz-wave parametric generator was constructed with MgO:LiNbO (3) crystals and a tunable seeder in a stationary dispersion-compensated optical arrangement. Without readjusting the mirrors, we obtained smooth tuning of the terahertz wave over the 0.6-2.6 THz range by adjusting the seeder wavelength alone. We have successfully demonstrated the feasibility of this system for terahertz-wave absorption measurements over a wide frequency range by using low-pressure water vapor. PMID:18033473

  15. Ultra-broadband achromatic imaging with diffractive photon sieves

    PubMed Central

    Zhao, Xiaonan; Hu, Jingpei; Lin, Yu; Xu, Feng; Zhu, Xiaojun; Pu, Donglin; Chen, Linsen; Wang, Chinhua

    2016-01-01

    Diffractive optical elements suffer from large chromatic aberration due to the strong wavelength-dependent nature in diffraction phenomena, and therefore, diffractive elements can work only at a single designed wavelength, which significantly limits the applications of diffractive elements in imaging. Here, we report on a demonstration of a wavefront coded broadband achromatic imaging with diffractive photon sieves. The broadband diffraction imaging is implemented with a wavefront coded pinhole pattern that generates equal focusing power for a wide range of operating wavelength in a single thin-film element without complicated auxiliary optical system. Experimental validation was performed using an UV-lithography fabricated wavefront coded photon sieves. Results show that the working bandwidth of the wavefront coded photon sieves reaches 28 nm compared with 0.32 nm of the conventional one. Further demonstration of the achromatic imaging with a bandwidth of 300 nm is also performed with a wavefront coded photon sieves integrated with a refractive element. PMID:27328713

  16. Ultra-broadband achromatic imaging with diffractive photon sieves

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaonan; Hu, Jingpei; Lin, Yu; Xu, Feng; Zhu, Xiaojun; Pu, Donglin; Chen, Linsen; Wang, Chinhua

    2016-06-01

    Diffractive optical elements suffer from large chromatic aberration due to the strong wavelength-dependent nature in diffraction phenomena, and therefore, diffractive elements can work only at a single designed wavelength, which significantly limits the applications of diffractive elements in imaging. Here, we report on a demonstration of a wavefront coded broadband achromatic imaging with diffractive photon sieves. The broadband diffraction imaging is implemented with a wavefront coded pinhole pattern that generates equal focusing power for a wide range of operating wavelength in a single thin-film element without complicated auxiliary optical system. Experimental validation was performed using an UV-lithography fabricated wavefront coded photon sieves. Results show that the working bandwidth of the wavefront coded photon sieves reaches 28 nm compared with 0.32 nm of the conventional one. Further demonstration of the achromatic imaging with a bandwidth of 300 nm is also performed with a wavefront coded photon sieves integrated with a refractive element.

  17. Metrology of achromatic diffractive features on chalcogenide lenses

    NASA Astrophysics Data System (ADS)

    Scordato, M.; Nelson, J.; Schwertz, K.; Mckenna, P.; Bagwell, J.

    2015-10-01

    Achromatic diffractive features on lenses are widely used in industry for color correction, however there is not a welldefined standard to quantify the performance of the lenses. One metric used to qualify a lens is the sag deviation from the nominal lens profile. Imperfections in the manufacturing of the diffractive feature may cause scattering and performance loss. This is not reflected in sag deviation measurements, therefore performance measurements are required. There are different quantitative approaches to measuring the performance of an achromatic diffractive lens. Diffraction efficiency, a measure of optical power throughput, is a common design metric used to define the percent drop from the modulation transfer function (MTF) metric. The line spread function (LSF) shows a layout of the intensity with linear distance and an ensquared energy specification can be implemented. The MTF is a common analysis tool for assemblies and can be applied to a single element. These functional tests will be performed and compared with diffractive lenses manufactured by different tool designs. This paper displays the results found with various instruments. Contact profilometry was used to inspect the profile of the diffractive elements, and a MTF bench was used to characterize lens performance. Included will be a discussion comparing the results of profile traces and beam profiles to expected diffraction efficiency values and the effects of manufacturing imperfections.

  18. Light detection and the wavelength shifter deposition in DEAP-3600

    NASA Astrophysics Data System (ADS)

    Broerman, B.; Retière, F.

    2016-02-01

    The Dark matter Experiment using Argon Pulse-shape discrimination (DEAP) uses liquid argon as a target medium to perform a direct-detection dark matter search. The 3600 kg liquid argon target volume is housed in a spherical acrylic vessel and viewed by a surrounding array of photomultiplier tubes. Ionizing particles in the argon volume produce scintillation light which must be wavelength shifted to be detected by the photomultiplier tubes. Argon scintillation and wavelength shifting, along with details on the application of the wavelength shifter to the inner surface of the acrylic vessel are presented.

  19. Factors affecting the performance of a multi-tone carrier source based re-circulating frequency shifter

    NASA Astrophysics Data System (ADS)

    Xi, Li-Xia; Li, Jian-Ping; Zhang, Xiao-Guang; Tian, Feng; Zhang, Wen-Bo

    2011-08-01

    Generation of single-sideband (SSB) multi-carrier source based on a recirculating frequency shifter (RFS) is analysed theoretically and realized experimentally. The effects of affecting factors originating from the deviation from the right operation bias voltage and unbalanced amplitude, and the phase of the radio frequency (RF) drive signals on the performance of the multi-tone source are discussed in detail. Based on the theoretical analysis, high-quality 50-tone output is successfully realized. Experiments under some implementation imperfections are also carried out. The imperfect and low-quality output results are in good agreement with theoretical analysis.

  20. Shape shifters: biobehavioral determinants and phenomena in symptom research.

    PubMed

    Corwin, Elizabeth J; Meek, Paula; Cook, Paul F; Lowe, Nancy K; Sousa, Karen H

    2012-01-01

    Symptom assessment and management are critical to patient-centered care. Traditionally, the determinants of a symptom are viewed as separate from the phenomena associated with that symptom. By separating determinants and phenomena, however, the complexity and dynamism of the patient experience are ignored. Likewise, categorizing symptom determinants and phenomena as solely biological or behavioral minimizes their dimensionality and may hinder interdisciplinary dialogue. Here we propose that determinants and phenomena are not fixed but shift between each other depending on perspective. To illustrate this way of thinking the metaphor of the "shape shifter" from folklore is used. A shape shifter moves between states and may be seen differently by the same person at different times or by multiple individuals at one time. To guide discussion, we present 5 exemplars of increasing complexity, wherein a determinant becomes a phenomenon or vice versa, depending upon context. Suggestions for statistical testing of the model are included with each. We conclude by exploring how shifting between determinants and phenomena may affect symptom cluster assessment and management.

  1. Achromatic registration of quadrature components of the optical spectrum in spectral domain optical coherence tomography

    SciTech Connect

    Shilyagin, P A; Gelikonov, G V; Gelikonov, V M; Moiseev, A A; Terpelov, D A

    2014-07-31

    We have thoroughly investigated the method of simultaneous reception of spectral components with the achromatised quadrature phase shift between two portions of a reference wave, designed for the effective suppression of the 'mirror' artefact in the resulting image obtained by means of spectral domain optical coherence tomography (SD OCT). We have developed and experimentally tested a phase-shifting element consisting of a beam divider, which splits the reference optical beam into the two beams, and of delay lines being individual for each beam, which create a mutual phase difference of π/2 in the double pass of the reference beam. The phase shift achromatism over a wide spectral range is achieved by using in the delay lines the individual elements with different dispersion characteristics. The ranges of admissible adjustment parameters of the achromatised delay line are estimated for exact and inexact conformity of the geometric characteristics of its components to those calculated. A possibility of simultaneous recording of the close-to-quadrature spectral components with a single linear photodetector element is experimentally confirmed. The suppression of the artefact mirror peak in the OCT-signal by an additional 9 dB relative to the level of its suppression is experimentally achieved when the air delay line is used. Two-dimensional images of the surface positioned at an angle to the axis of the probe beam are obtained with the correction of the 'mirror' artefact while maintaining the dynamic range of the image. (laser biophotonics)

  2. Size, weight, and power reduction regimes in achromatic gradient-index singlets.

    PubMed

    Campbell, Sawyer D; Brocker, Donovan E; Nagar, Jogender; Werner, Douglas H

    2016-05-01

    By analyzing the limitations that achromatic gradient-index (GRIN) lens solutions in the radial and axial extremes place on lens thickness and surface curvature, a radial-axial hybrid GRIN theory is developed in order to overcome these restrictions and expose a larger solution space. With the achromatic hybrid GRIN theory, the trade-offs between thickness, curvature, and GRIN type can be directly studied in the context of size, weight, and power (SWaP) reduction. Finally, the achromatic solution space of a silicon-germanium-based material system is explored, and several designs are verified with ray tracing. PMID:27140376

  3. Symmetric Achromatic Low-Beta Collider Interaction Region Design Concept

    SciTech Connect

    Morozov, Vasiliy S.; Derbenev, Yaroslav S.; Lin, Fanglei; Johnson, Rolland P.

    2013-01-01

    We present a new symmetry-based concept for an achromatic low-beta collider interaction region design. A specially-designed symmetric Chromaticity Compensation Block (CCB) induces an angle spread in the passing beam such that it cancels the chromatic kick of the final focusing quadrupoles. Two such CCB?s placed symmetrically around an interaction point allow simultaneous compensation of the 1st-order chromaticities and chromatic beam smear at the IP without inducing significant 2nd-order aberrations. We first develop an analytic description of this approach and explicitly formulate 2nd-order aberration compensation conditions at the interaction point. The concept is next applied to develop an interaction region design for the ion collider ring of an electron-ion collider. We numerically evaluate performance of the design in terms of momentum acceptance and dynamic aperture. The advantages of the new concept are illustrated by comparing it to the conventional distributed-sextupole chromaticity compensation scheme.

  4. A Second-Order Achromat Design Based on FODO Cell

    SciTech Connect

    Sun, Yipeng; /SLAC

    2011-08-19

    Two dipole doglegs are widely used to translate the beam axis horizontally or vertically. Quadrupoles are placed between the two consecutive dipoles to match first order dispersion and provide betatron focusing. Similarly a four dipole chicane is usually employed to form a bypass region, where the beam axis is transversely shifted first, then translated back to the original axis. In order to generate an isochronous section, quadrupoles are again needed to tune the first order transfer matrix element R{sub 56} equaling zero. Usually sextupoles are needed to correct second order dispersion in the bending plane, for both the dogleg optics and the chicane (with quad) optics. In this paper, an alternative optics design is introduced, which is based on a simple FODO cell and does not need sextupoles assistance to form a second-order achromat. It may provide a similar function of either a dogleg or a bypass, by using 2 or 4 of such combined supercells.

  5. Fabrication and measurements of hybrid Nb/Al Josephson junctions and flux qubits with π-shifters

    NASA Astrophysics Data System (ADS)

    Shcherbakova, A. V.; Fedorov, K. G.; Shulga, K. V.; Ryazanov, V. V.; Bolginov, V. V.; Oboznov, V. A.; Egorov, S. V.; Shkolnikov, V. O.; Wolf, M. J.; Beckmann, D.; Ustinov, A. V.

    2015-02-01

    We describe fabrication and testing of composite flux qubits combining Nb- and Al-based superconducting circuit technology. This hybrid approach to making qubits allows for employing π-phase shifters fabricated using well-established Nb-based technology of superconductor-ferromagnet-superconductor Josephson junctions. The important feature here is to obtain high interface transparency between Nb and Al layers without degrading sub-micron shadow mask. We achieve this by in situ Ar etching using e-beam gun. Shadow-evaporated Al/AlOx/Al Josephson junctions with Nb bias pads show the expected current-voltage characteristics with reproducible critical currents. Using this technique, we fabricated composite Nb/Al flux qubits with Nb/CuNi/Nb π-shifters and measured their magnetic field response. The observed offset between the field responses of the qubits with and without π-junction is attributed to the π phase shift. The reported approach can be used for implementing a variety of hybrid Nb/Al superconducting quantum circuits.

  6. Low voltage to high voltage level shifter and related methods

    NASA Technical Reports Server (NTRS)

    Mentze, Erik J. (Inventor); Hess, Herbert L. (Inventor); Buck, Kevin M. (Inventor); Cox, David F. (Inventor)

    2006-01-01

    A shifter circuit comprises a high and low voltage buffer stages and an output buffer stage. The high voltage buffer stage comprises multiple transistors arranged in a transistor stack having a plurality of intermediate nodes connecting individual transistors along the stack. The transistor stack is connected between a voltage level being shifted to and an input voltage. An inverter of this stage comprises multiple inputs and an output. Inverter inputs are connected to a respective intermediate node of the transistor stack. The low voltage buffer stage has an input connected to the input voltage and an output, and is operably connected to the high voltage buffer stage. The low voltage buffer stage is connected between a voltage level being shifted away from and a lower voltage. The output buffer stage is driven by the outputs of the high voltage buffer stage inverter and the low voltage buffer stage.

  7. Spatially and spectrally engineered spin-orbit interaction for achromatic virtual shaping.

    PubMed

    Pu, Mingbo; Zhao, Zeyu; Wang, Yanqin; Li, Xiong; Ma, Xiaoliang; Hu, Chenggang; Wang, Changtao; Huang, Cheng; Luo, Xiangang

    2015-05-11

    The geometries of objects are deterministic in electromagnetic phenomena in all aspects of our world, ranging from imaging with spherical eyes to stealth aircraft with bizarre shapes. Nevertheless, shaping the physical geometry is often undesired owing to other physical constraints such as aero- and hydro-dynamics in the stealth technology. Here we demonstrate that it is possible to change the traditional law of reflection as well as the electromagnetic characters without altering the physical shape, by utilizing the achromatic phase shift stemming from spin-orbit interaction in ultrathin space-variant and spectrally engineered metasurfaces. The proposal is validated by full-wave simulations and experimental characterization in optical wavelengths ranging from 600 nm to 2800 nm and microwave frequencies in 8-16 GHz, with echo reflectance less than 10% in the whole range. The virtual shaping as well as the revised law of reflection may serve as a versatile tool in many realms, including broadband and conformal camouflage and Kinoform holography, to name just a few.

  8. Spatially and spectrally engineered spin-orbit interaction for achromatic virtual shaping

    PubMed Central

    Pu, Mingbo; Zhao, Zeyu; Wang, Yanqin; Li, Xiong; Ma, Xiaoliang; Hu, Chenggang; Wang, Changtao; Huang, Cheng; Luo, Xiangang

    2015-01-01

    The geometries of objects are deterministic in electromagnetic phenomena in all aspects of our world, ranging from imaging with spherical eyes to stealth aircraft with bizarre shapes. Nevertheless, shaping the physical geometry is often undesired owing to other physical constraints such as aero- and hydro-dynamics in the stealth technology. Here we demonstrate that it is possible to change the traditional law of reflection as well as the electromagnetic characters without altering the physical shape, by utilizing the achromatic phase shift stemming from spin-orbit interaction in ultrathin space-variant and spectrally engineered metasurfaces. The proposal is validated by full-wave simulations and experimental characterization in optical wavelengths ranging from 600 nm to 2800 nm and microwave frequencies in 8-16 GHz, with echo reflectance less than 10% in the whole range. The virtual shaping as well as the revised law of reflection may serve as a versatile tool in many realms, including broadband and conformal camouflage and Kinoform holography, to name just a few. PMID:25959663

  9. Spatially and spectrally engineered spin-orbit interaction for achromatic virtual shaping.

    PubMed

    Pu, Mingbo; Zhao, Zeyu; Wang, Yanqin; Li, Xiong; Ma, Xiaoliang; Hu, Chenggang; Wang, Changtao; Huang, Cheng; Luo, Xiangang

    2015-01-01

    The geometries of objects are deterministic in electromagnetic phenomena in all aspects of our world, ranging from imaging with spherical eyes to stealth aircraft with bizarre shapes. Nevertheless, shaping the physical geometry is often undesired owing to other physical constraints such as aero- and hydro-dynamics in the stealth technology. Here we demonstrate that it is possible to change the traditional law of reflection as well as the electromagnetic characters without altering the physical shape, by utilizing the achromatic phase shift stemming from spin-orbit interaction in ultrathin space-variant and spectrally engineered metasurfaces. The proposal is validated by full-wave simulations and experimental characterization in optical wavelengths ranging from 600 nm to 2800 nm and microwave frequencies in 8-16 GHz, with echo reflectance less than 10% in the whole range. The virtual shaping as well as the revised law of reflection may serve as a versatile tool in many realms, including broadband and conformal camouflage and Kinoform holography, to name just a few. PMID:25959663

  10. Athermal achromat lens enabled by polymer gradient index optics

    NASA Astrophysics Data System (ADS)

    Flynn, Richard A.; Beadie, Guy

    2016-05-01

    An optical design is shown which provides simultaneous color correction over the visible spectrum and passive thermal compensation, for an f/4 doublet made of a glass and a polymer gradient index (GRIN) element. The design is enabled by a new optical model for the thermally varying GRIN element, which incorporates measured material properties from 20-40°C (limited only by the extent of the measured data set). The design is made possible because of the GRIN degrees of freedom available to the material. A color-corrected doublet is most efficient when there is a large ratio of the dispersion strength (Abbe number) between the two materials. To make that doublet athermal, however, there needs to be an equally high ratio between the thermal coefficients. The large ratio of polymer to glass thermal coefficients presents a unique advantage for GRIN: the effective GRIN dispersion coefficient can have just as large a ratio to the glass as the thermal coefficients, making for a powerful athermal achromat. To our knowledge, this is the first example of a polymer GRIN used for simultaneous chromatic and thermal correction.

  11. CIAXE: co-axial achromatic interferential coronagraph: first laboratory results

    NASA Astrophysics Data System (ADS)

    Allouche, Fatmé; Gay, Jean; Rabbia, Yves; Assus, Pierre

    2010-07-01

    In 1996, Jean Gay and Yves Rabbia presented their Achromatic Interferential Coronagraph (AIC) for detecting and imaging faint companions (ultimately exoplanets) in the neighboring of a star. As presented then, the Michleson-like Interferometer configuration of the AIC hardens its insertion into an existing (coaxial) optical train, the output beam of the AIC being delivered at right angle from the input beam. To overcome this, they reconfigured the AIC into a compact and fully axial coronagraph, the CIAXE, which main feature consists of using two thick lenses machined in the same optical material. For the CIAXE to deliver the output beam along the same axis as the input beam, the two lenses are coaxially disposed on the optical axis and are separated, at their common spherical contact surface by a thin air gap acting like a beam splitter. We have set up a laboratory experiment aiming at validating the principle of the concept. Our first step was to equalize the thicknesses of the two lenses, so as to make zero the optical path difference between both arms. For this, the (residual) value of the OPD has been evaluated and then the lenses have been re-machined so as to decrease as far as technologically possible, the thicknesses mismatch. As a second step, a micro-controlled rotation around the common curvature center of the spherical surfaces of the lenses is applied. This allows a fine tuning of the residual OPD at the required accuracy level. Are presented here test bench, steps and results.

  12. Edge detection depends on achromatic channel in Drosophila melanogaster.

    PubMed

    Zhou, Yanqiong; Ji, Xiaoxiao; Gong, Haiyun; Gong, Zhefeng; Liu, Li

    2012-10-01

    Edges represent important information in object recognition, and thus edge detection is crucial for animal survival. Various types of edges result from visual contrast, such as luminance contrast and color contrast. So far, the molecular and neural mechanisms underlying edge detection and the relationship between different edge information-processing pathways have been largely undemonstrated. In the present study, using a color light-emitting-diode-based Buridan's paradigm, we demonstrated that a blue/green demarcation is able to generate edge-orientation behavior in the adult fly. There is a blue/green intensity ratio, the so-called point of equal luminance, at which wild-type flies did not show obvious orientation behavior towards edges. This suggests that orientation behavior towards edges is dependent on luminance contrast in Drosophila. The results of mutants ninaE(17) and sev(LY3);rh5(2);rh6(1) demonstrated that achromatic R1-R6 photoreceptor cells, but not chromatic R7/R8 photoreceptor cells, were necessary for orientation behavior towards edges. Moreover, ectopic expression of rhodopsin 4 (Rh4), Rh5 or Rh6 could efficiently restore the edge-orientation defect in the ninaE(17) mutant. Altogether, our results show that R1-R6 photoreceptor cells are both necessary and sufficient for orientation behavior towards edges in Drosophila. PMID:22735352

  13. Slow updating of the achromatic point after a change in illumination

    PubMed Central

    Lee, R. J.; Dawson, K. A.; Smithson, H. E.

    2015-01-01

    For a colour constant observer, the colour appearance of a surface is independent of the spectral composition of the light illuminating it. We ask how rapidly colour appearance judgements are updated following a change in illumination. We obtained repeated binary colour classifications for a set of stimuli defined by their reflectance functions and rendered under either sunlight or skylight. We used these classifications to derive boundaries in colour space that identify the observer’s achromatic point. In steady-state conditions of illumination, the achromatic point lay close to the illuminant chromaticity. In our experiment the illuminant changed abruptly every 21 seconds (at the onset of every 10th trial), allowing us to track changes in the achromatic point that were caused by the cycle of illuminant changes. In one condition, the test reflectance was embedded in a spatial pattern of reflectance samples under consistent illumination. The achromatic point migrated across colour space between the chromaticities of the steady-state achromatic points. This update took several trials rather than being immediate. To identify the factors that governed perceptual updating of appearance judgements we used two further conditions, one in which the test reflectance was presented in isolation and one in which the surrounding reflectances were rendered under an inconsistent and unchanging illumination. Achromatic settings were not well predicted by the information available from scenes at a single time-point. Instead the achromatic points showed a strong dependence on the history of chromatic samples. The strength of this dependence differed between observers and was modulated by the spatial context. PMID:22275468

  14. Wavelength Shifters and Interactions of EDTA with Acrylic & LAB

    NASA Astrophysics Data System (ADS)

    Mohan, Yuvraj; SNO+ Collaboration

    2014-09-01

    The SNO + experiment, an upgrade to the Sudbury Neutrino Observatory, will use linear alkyl-benzene (LAB) liquid scintillator to probe new physics, including 0 νββ decay. Event detection efficiency is heavily affected by radioactive backgrounds, two sources being Rn-222 and Po-210 daughters, some of which has become embedded in the SNO + acrylic vessel after years underground. The leading candidate for polonium leaching is Ethylenediaminetetraacetic acid (EDTA). Before deployment on-site, EDTA's effects on the mechanical integrity of acrylic must be determined. It also must not be soluble in LAB or must be removed before scintillator fill of the vessel, as its presence would result in reduced light yield due to scattering. It was found that EDTA had negligible effects on the Young's Modulus of acrylic. EDTA is also slightly soluble in LAB, but can be completely removed by rinsing with water. Additionally, the study of the light yield and alpha/beta timing profiles of two wavelength shifters - bisMSB and perylene - is critical to determining which should be added to the 0 νββ isotope (tellurium) LAB cocktail. Small-scale results hint that perylene might be better, but this is being confirmed with larger-scale tests. The SNO + experiment, an upgrade to the Sudbury Neutrino Observatory, will use linear alkyl-benzene (LAB) liquid scintillator to probe new physics, including 0 νββ decay. Event detection efficiency is heavily affected by radioactive backgrounds, two sources being Rn-222 and Po-210 daughters, some of which has become embedded in the SNO + acrylic vessel after years underground. The leading candidate for polonium leaching is Ethylenediaminetetraacetic acid (EDTA). Before deployment on-site, EDTA's effects on the mechanical integrity of acrylic must be determined. It also must not be soluble in LAB or must be removed before scintillator fill of the vessel, as its presence would result in reduced light yield due to scattering. It was found that EDTA

  15. Design and imaging performance of achromatic diffractive-refractive x-ray and gamma-ray Fresnel lenses.

    PubMed

    Skinner, Gerald K

    2004-09-01

    Achromatic combinations of a diffractive phase Fresnel lens and a refractive correcting element have been proposed for x-ray and gamma-ray astronomy and for microlithography, but considerations of absorption often dictate that the refractive component be given a stepped profile, resulting in a double Fresnel lens. The imaging performance of corrected Fresnel lenses, with and without stepping, is investigated, and the trade-off between resolution and useful bandwidth in different circumstances is discussed. Provided that the focal ratio is large, correction lenses made from low atomic number materials can be used with x rays in the range of approximately 10-100 keV without stepping. The use of stepping extends the possibility of correction to higher-aperture systems, to energies as low as a few kilo electron volts, and to gamma rays of mega electron volt energy.

  16. Distributed phased array architecture study

    NASA Technical Reports Server (NTRS)

    Bourgeois, Brian

    1987-01-01

    Variations in amplifiers and phase shifters can cause degraded antenna performance, depending also on the environmental conditions and antenna array architecture. The implementation of distributed phased array hardware was studied with the aid of the DISTAR computer program as a simulation tool. This simulation provides guidance in hardware simulation. Both hard and soft failures of the amplifiers in the T/R modules are modeled. Hard failures are catastrophic: no power is transmitted to the antenna elements. Noncatastrophic or soft failures are modeled as a modified Gaussian distribution. The resulting amplitude characteristics then determine the array excitation coefficients. The phase characteristics take on a uniform distribution. Pattern characteristics such as antenna gain, half power beamwidth, mainbeam phase errors, sidelobe levels, and beam pointing errors were studied as functions of amplifier and phase shifter variations. General specifications for amplifier and phase shifter tolerances in various architecture configurations for C band and S band were determined.

  17. Achromatic interfero-coronagraph with variable rotational shear in laboratory experiments

    NASA Astrophysics Data System (ADS)

    Frolov, Pavel; Kiselev, Alexander; Tavrov, Alexander

    2016-07-01

    Direct imaging of earth-like extrasolar planets in the habitable zone and the search for possible biological signatures are among the key scientific objectives in the modern astronomy. Stellar coronagraph such as achromatic interfero coronagraph (AIC) with a small inner working angle has limited possibilities to detect and characterize planets around nearby stars due to the star leakage effect caused by incomplete suppression of the star of finite angular size. We report on an improved instrument for direct imaging of exoplanets and the study of stellar environment - common-path achromatic interfero-coronagraph with variable rotational shear (common-path achromatic rotation-shearing coronagraph, CP-ARC) - a common path implementation of rotation shearing interferometer. We detail CP-ARC approach and discuss its optical configuration, laboratory prototype and experimental results.

  18. Generic conditions for suppressing the coherent synchrotron radiation induced emittance growth in a two-dipole achromat

    NASA Astrophysics Data System (ADS)

    Jiao, Yi; Cui, Xiaohao; Huang, Xiyang; Xu, Gang

    2014-06-01

    The effect of the coherent synchrotron radiation (CSR) becomes evident, and leads to increased beam energy spread and transverse emittance dilution, as both the emittance and bunch length of the electron beams are continuously pushed down in present and forthcoming high-brightness light sources and linear colliders. Suppressing this effect is important to preserve the expected machine performance. Methods of the R-matrix analysis and the Courant-Snyder formalism analysis have been proposed to evaluate and to suppress the emittance growth due to CSR in achromatic cells. In this paper a few important modifications are made on these two methods, which enable us to prove that these two methods are equivalent to each other. With the modified analysis, we obtain explicit and generic conditions of cancelling the CSR-driven emittance excitation in a single achromat consisting of two dipoles of arbitrary bending angles. In spite of the fact that the analysis constrains itself in a linear regime, based on the assumption that CSR-induced particle energy deviation is proportional to both θ and ρ1/3, with θ being the bending angle and ρ the bending radius, it is demonstrated through ELEGANT simulations that the conditions derived from this analysis are still effective in suppressing the emittance growth when a more detailed one-dimensional CSR model is considered. In addition, it illustrates that the emittance growth can be reduced to a lower level with the proposed conditions than with the other two approaches, such as matching the beam envelope to the CSR kick and setting the cell-to-cell betatron phase advance to an appropriate value.

  19. Achromatic circular polarizer in the 482-535 nm range based on polypropylene films

    NASA Astrophysics Data System (ADS)

    Muravsky, Al. A.; Murauski, An. A.; Agabekov, V. E.; Chuvasheva, O. O.; Ivanova, N. A.

    2012-11-01

    We present a design for an achromatic circular polarizer based on polypropylene films. The circular polarizer, having eccentricity ≥0.92 in the 482-535 nm range and ideally circular for the wavelength of ~505 nm, is obtained by combining BOPP C2-25 and BOPP C2-35 films of thickness 23 m and 33 μm.

  20. Integrated nanophotonic frequency shifter on the silicon-organic hybrid (SOH) platform for laser vibrometry

    SciTech Connect

    Lauermann, M.; Weimann, C.; Palmer, R.; Schindler, P. C.; Koeber, S.; Freude, W. Koos, C.; Rembe, C.

    2014-05-27

    We demonstrate a waveguide-based frequency shifter on the silicon photonic platform, enabling frequency shifts up to 10 GHz. The device is realized by silicon-organic hybrid (SOH) integration. Temporal shaping of the drive signal allows the suppression of spurious side-modes by more than 23 dB.

  1. Phased-array radars

    NASA Astrophysics Data System (ADS)

    Brookner, E.

    1985-02-01

    The operating principles, technology, and applications of phased-array radars are reviewed and illustrated with diagrams and photographs. Consideration is given to the antenna elements, circuitry for time delays, phase shifters, pulse coding and compression, and hybrid radars combining phased arrays with lenses to alter the beam characteristics. The capabilities and typical hardware of phased arrays are shown using the US military systems COBRA DANE and PAVE PAWS as examples.

  2. Design study of a low-emittance lattice with a five-bend achromat

    NASA Astrophysics Data System (ADS)

    Liu, Hao-Lin; Kim, Eun-San

    2016-04-01

    The multi-bend achromat (MBA) lattice, which can provide a small horizontal emittance in the subnanometer range, shows promise for future storage-ring-based light-source facilities. We present the linear and the nonlinear properties of an optical design and the results of its optimization. The MBA lattice is designed as a five-bend achromat, and an emittance of 0.270 nm rad is achieved. The energy and the circumference of the designed ring are 3 GeV and 499.3 m, respectively. We investigated an injection system with a single-pulsed sextupole magnet in the storage ring. We describe the space allocation in the injection section and the particle dynamics of the injected beam. The investigation shows that our design exhibits a very low emittance and a sufficient dynamic aperture, and provides a suitable injection scheme for a 3-GeV light source.

  3. Design and modeling of a cost-effective achromatic Fresnel lens for concentrating photovoltaics.

    PubMed

    Vallerotto, Guido; Victoria, Marta; Askins, Stephen; Herrero, Rebeca; Domínguez, César; Antón, Ignacio; Sala, Gabriel

    2016-09-01

    This paper presents a novel Fresnel lens capable of significantly reducing chromatic aberration in solar applications. The optical performance of this achromatic lens has been analyzed through ray-tracing simulations, showing a concentration factor three times higher than that attained by a classic silicone on glass (SOG) Fresnel lens while maintaining the same acceptance angle. This should avoid the need for a secondary optical element, reducing the cost associated with its manufacturing and assembly and increasing the module reliability. The achromatic lens is made of inexpensive plastic and elastomer which allows a highly scalable and cost-competitive manufacturing process similar to the one currently used for the fabrication of SOG Fresnel lenses.

  4. Design and modeling of a cost-effective achromatic Fresnel lens for concentrating photovoltaics.

    PubMed

    Vallerotto, Guido; Victoria, Marta; Askins, Stephen; Herrero, Rebeca; Domínguez, César; Antón, Ignacio; Sala, Gabriel

    2016-09-01

    This paper presents a novel Fresnel lens capable of significantly reducing chromatic aberration in solar applications. The optical performance of this achromatic lens has been analyzed through ray-tracing simulations, showing a concentration factor three times higher than that attained by a classic silicone on glass (SOG) Fresnel lens while maintaining the same acceptance angle. This should avoid the need for a secondary optical element, reducing the cost associated with its manufacturing and assembly and increasing the module reliability. The achromatic lens is made of inexpensive plastic and elastomer which allows a highly scalable and cost-competitive manufacturing process similar to the one currently used for the fabrication of SOG Fresnel lenses. PMID:27607727

  5. Feed-forward digital phase and amplitude correction system

    DOEpatents

    Yu, David U. L.; Conway, Patrick H.

    1994-01-01

    Phase and amplitude modifications in repeatable RF pulses at the output of a high power pulsed microwave amplifier are made utilizing a digital feed-forward correction system. A controlled amount of the output power is coupled to a correction system for processing of phase and amplitude information. The correction system comprises circuitry to compare the detected phase and amplitude with the desired phase and amplitude, respectively, and a digitally programmable phase shifter and attenuator and digital logic circuitry to control the phase shifter and attenuator. The Phase and amplitude of subsequent are modified by output signals from the correction system.

  6. Feed-forward digital phase and amplitude correction system

    DOEpatents

    Yu, D.U.L.; Conway, P.H.

    1994-11-15

    Phase and amplitude modifications in repeatable RF pulses at the output of a high power pulsed microwave amplifier are made utilizing a digital feed-forward correction system. A controlled amount of the output power is coupled to a correction system for processing of phase and amplitude information. The correction system comprises circuitry to compare the detected phase and amplitude with the desired phase and amplitude, respectively, and a digitally programmable phase shifter and attenuator and digital logic circuitry to control the phase shifter and attenuator. The phase and amplitude of subsequent are modified by output signals from the correction system. 11 figs.

  7. Behavioural and electrophysiological chromatic and achromatic contrast sensitivity in an achromatopsic patient.

    PubMed Central

    Heywood, C A; Nicholas, J J; Cowey, A

    1996-01-01

    OBJECTIVES--In cases of incomplete achromatopsia it is unclear whether residual visual function is mediated by intact striate cortex or results from incomplete lesions to extrastriate cortical visual areas. A patient with complete cerebral achromatopsia was tested to establish the nature of his residual vision and to determine the integrity of striate cortex function. METHODS--Behavioural contrast sensitivity, using the method of adjustment, and averaged visually evoked cortical potentials were measured to sinusoidally modulated chromatic and achromatic gratings in an achromatopsic patient and a normal observer. Eye movements were measured in the patient using a Skalar infrared monitoring system. RESULTS--The patient's chromatic contrast sensitivity was normal, indicating that despite his dense colour blindness his occipital cortex still processed information about spatial variations in hue. His sensitivity to achromatic gratings was depressed particularly at high spatial frequencies, possibly because of his jerk nystagmus. These behavioural results were reinforced by the nature of visually evoked responses to chromatic and achromatic gratings, in which total colour blindness coexisted with an almost normal cortical potential to isoluminant chromatic gratings. CONCLUSIONS--The results show that information about chromatic contrast is present in some cortical areas, and coded in a colour-opponent fashion, in the absence of any perceptual experience of colour. PMID:8648330

  8. Orientation tuning of binocular summation: a comparison of colour to achromatic contrast

    PubMed Central

    Gheiratmand, Mina; Cherniawsky, Avital S.; Mullen, Kathy T.

    2016-01-01

    A key function of the primary visual cortex is to combine the input from the two eyes into a unified binocular percept. At low, near threshold, contrasts a process of summation occurs if the visual inputs from the two eyes are similar. Here we measure the orientation tuning of binocular summation for chromatic and equivalent achromatic contrast. We derive estimates of orientation tuning by measuring binocular summation as a function of the orientation difference between two sinusoidal gratings presented dichoptically to different eyes. We then use a model to estimate the orientation bandwidth of the neural detectors underlying the binocular combination. We find that orientation bandwidths are similar for chromatic and achromatic stimuli at both low (0.375 c/deg) and mid (1.5 c/deg) spatial frequencies, with an overall average of 29 ± 3 degs (HWHH, s.e.m). This effect occurs despite the overall greater binocular summation found for the low spatial frequency chromatic stimuli. These results suggest that similar, oriented processes underlie both chromatic and achromatic binocular contrast combination. The non-oriented detection process found in colour vision at low spatial frequencies under monocular viewing is not evident at the binocular combination stage. PMID:27168119

  9. Achromatic vector vortex beams from a glass cone.

    PubMed

    Radwell, N; Hawley, R D; Götte, J B; Franke-Arnold, S

    2016-01-01

    The reflection of light is governed by the laws first described by Augustin-Jean Fresnel: on internal reflection, light acquires a phase shift, which depends on its polarization direction with respect to the plane of incidence. For a conical reflector, the cylindrical symmetry is echoed in an angular variation of this phase shift, allowing us to create light modes with phase and polarization singularities. Here we observe the phase and polarization profiles of light that is back reflected from a solid glass cone and, in the case of circular input light, discover that not only does the beam contain orbital angular momentum but can trivially be converted to a radially polarized beam. Importantly, the Fresnel coefficients are reasonably stable across the visible spectrum, which we demonstrate by measuring white light polarization profiles. This discovery provides a highly cost-effective technique for the generation of broadband orbital angular momentum and radially polarized beams. PMID:26861191

  10. Achromatic vector vortex beams from a glass cone

    PubMed Central

    Radwell, N.; Hawley, R. D.; Götte, J. B.; Franke-Arnold, S.

    2016-01-01

    The reflection of light is governed by the laws first described by Augustin-Jean Fresnel: on internal reflection, light acquires a phase shift, which depends on its polarization direction with respect to the plane of incidence. For a conical reflector, the cylindrical symmetry is echoed in an angular variation of this phase shift, allowing us to create light modes with phase and polarization singularities. Here we observe the phase and polarization profiles of light that is back reflected from a solid glass cone and, in the case of circular input light, discover that not only does the beam contain orbital angular momentum but can trivially be converted to a radially polarized beam. Importantly, the Fresnel coefficients are reasonably stable across the visible spectrum, which we demonstrate by measuring white light polarization profiles. This discovery provides a highly cost-effective technique for the generation of broadband orbital angular momentum and radially polarized beams. PMID:26861191

  11. Control of phased-array antennas

    NASA Astrophysics Data System (ADS)

    Samoilenko, V. I.; Shishov, Iu. A.

    Principles and algorithms for the control of phased arrays are described. Particular consideration is given to algorithms for the control of phase distribution, adaptive arrays, beam-steerable arrays, the design of phase shifters, the compensation of beam-pointing errors, and the calibration of high-gain antenna pointing.

  12. Integrated optical frequency shifter in silicon-organic hybrid (SOH) technology.

    PubMed

    Lauermann, M; Weimann, C; Knopf, A; Heni, W; Palmer, R; Koeber, S; Elder, D L; Bogaerts, W; Leuthold, J; Dalton, L R; Rembe, C; Freude, W; Koos, C

    2016-05-30

    We demonstrate for the first time a waveguide-based frequency shifter on the silicon photonic platform using single-sideband modulation. The device is based on silicon-organic hybrid (SOH) electro-optic modulators, which combine conventional silicon-on-insulator waveguides with highly efficient electro-optic cladding materials. Using small-signal modulation, we demonstrate frequency shifts of up to 10 GHz. We further show large-signal modulation with optimized waveforms, enabling a conversion efficiency of -5.8 dB while suppressing spurious side-modes by more than 23 dB. In contrast to conventional acousto-optic frequency shifters, our devices lend themselves to large-scale integration on silicon substrates, while enabling frequency shifts that are several orders of magnitude larger than those demonstrated with all-silicon serrodyne devices. PMID:27410095

  13. Achromatic diffractive lens written onto a liquid crystal display.

    PubMed

    Márquez, A; Iemmi, C; Campos, J; Yzuel, M J

    2006-02-01

    We propose a programmable diffractive lens written onto a liquid crystal display (LCD) that is able to provide equal focal lengths for several wavelengths simultaneously. To achieve this goal it is necessary that the LCD operate in the phase-only regime simultaneously for the different wavelengths. We design the appropriate lens for each wavelength, and then the lenses are spatially multiplexed onto the LCD. Various multiplexing schemes have been analyzed, and the random scheme shows the best performance. We further show the possibility of finely tuning the chromaticity of the focal spot by changing the relative weights of the multiplexing among the various wavelengths.

  14. Catenary optics for achromatic generation of perfect optical angular momentum.

    PubMed

    Pu, Mingbo; Li, Xiong; Ma, Xiaoliang; Wang, Yanqin; Zhao, Zeyu; Wang, Changtao; Hu, Chenggang; Gao, Ping; Huang, Cheng; Ren, Haoran; Li, Xiangping; Qin, Fei; Yang, Jing; Gu, Min; Hong, Minghui; Luo, Xiangang

    2015-10-01

    The catenary is the curve that a free-hanging chain assumes under its own weight, and thought to be a "true mathematical and mechanical form" in architecture by Robert Hooke in the 1670s, with nevertheless no significant phenomena observed in optics. We show that the optical catenary can serve as a unique building block of metasurfaces to produce continuous and linear phase shift covering [0, 2π], a mission that is extremely difficult if not impossible for state-of-the-art technology. Via catenary arrays, planar optical devices are designed and experimentally characterized to generate various kinds of beams carrying orbital angular momentum (OAM). These devices can operate in an ultra-broadband spectrum because the anisotropic modes associated with the spin-orbit interaction are almost independent of the incident light frequency. By combining the optical and topological characteristics, our approach would allow the complete control of photons within a single nanometric layer. PMID:26601283

  15. Catenary optics for achromatic generation of perfect optical angular momentum

    PubMed Central

    Pu, Mingbo; Li, Xiong; Ma, Xiaoliang; Wang, Yanqin; Zhao, Zeyu; Wang, Changtao; Hu, Chenggang; Gao, Ping; Huang, Cheng; Ren, Haoran; Li, Xiangping; Qin, Fei; Yang, Jing; Gu, Min; Hong, Minghui; Luo, Xiangang

    2015-01-01

    The catenary is the curve that a free-hanging chain assumes under its own weight, and thought to be a “true mathematical and mechanical form” in architecture by Robert Hooke in the 1670s, with nevertheless no significant phenomena observed in optics. We show that the optical catenary can serve as a unique building block of metasurfaces to produce continuous and linear phase shift covering [0, 2π], a mission that is extremely difficult if not impossible for state-of-the-art technology. Via catenary arrays, planar optical devices are designed and experimentally characterized to generate various kinds of beams carrying orbital angular momentum (OAM). These devices can operate in an ultra-broadband spectrum because the anisotropic modes associated with the spin-orbit interaction are almost independent of the incident light frequency. By combining the optical and topological characteristics, our approach would allow the complete control of photons within a single nanometric layer. PMID:26601283

  16. Catenary optics for achromatic generation of perfect optical angular momentum.

    PubMed

    Pu, Mingbo; Li, Xiong; Ma, Xiaoliang; Wang, Yanqin; Zhao, Zeyu; Wang, Changtao; Hu, Chenggang; Gao, Ping; Huang, Cheng; Ren, Haoran; Li, Xiangping; Qin, Fei; Yang, Jing; Gu, Min; Hong, Minghui; Luo, Xiangang

    2015-10-01

    The catenary is the curve that a free-hanging chain assumes under its own weight, and thought to be a "true mathematical and mechanical form" in architecture by Robert Hooke in the 1670s, with nevertheless no significant phenomena observed in optics. We show that the optical catenary can serve as a unique building block of metasurfaces to produce continuous and linear phase shift covering [0, 2π], a mission that is extremely difficult if not impossible for state-of-the-art technology. Via catenary arrays, planar optical devices are designed and experimentally characterized to generate various kinds of beams carrying orbital angular momentum (OAM). These devices can operate in an ultra-broadband spectrum because the anisotropic modes associated with the spin-orbit interaction are almost independent of the incident light frequency. By combining the optical and topological characteristics, our approach would allow the complete control of photons within a single nanometric layer.

  17. A tale of two retinal domains: near-optimal sampling of achromatic contrasts in natural scenes through asymmetric photoreceptor distribution.

    PubMed

    Baden, Tom; Schubert, Timm; Chang, Le; Wei, Tao; Zaichuk, Mariana; Wissinger, Bernd; Euler, Thomas

    2013-12-01

    For efficient coding, sensory systems need to adapt to the distribution of signals to which they are exposed. In vision, natural scenes above and below the horizon differ in the distribution of chromatic and achromatic features. Consequently, many species differentially sample light in the sky and on the ground using an asymmetric retinal arrangement of short- (S, "blue") and medium- (M, "green") wavelength-sensitive photoreceptor types. Here, we show that in mice this photoreceptor arrangement provides for near-optimal sampling of natural achromatic contrasts. Two-photon population imaging of light-driven calcium signals in the synaptic terminals of cone-photoreceptors expressing a calcium biosensor revealed that S, but not M cones, preferred dark over bright stimuli, in agreement with the predominance of dark contrasts in the sky but not on the ground. Therefore, the different cone types do not only form the basis of "color vision," but in addition represent distinct (achromatic) contrast-selective channels.

  18. Super-achromatic microprobe for ultrahigh-resolution endoscopic OCT imaging at 800 nm (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Yuan, Wu; Alemohammad, Milad; Yu, Xiaoyun; Yu, Shaoyong; Li, Xingde

    2016-03-01

    In this paper, we report a super-achromatic microprobe made with fiber-optic ball lens to enable ultrahigh-resolution endoscopic OCT imaging. An axial resolution of ~2.4 µm (in air) can be achieved with a 7-fs Ti:Sapphire laser. The microprobe has minimal astigmatism which affords a high transverse resolution of ~5.6 µm. The miniaturized microprobe has an outer diameter of ~520 µm including the encasing metal guard and can be used to image small luminal organs. The performance of the ultrahigh-resolution OCT microprobe was demonstrated by imaging rat esophagus, guinea pig esophagus, and mouse rectum in vivo.

  19. Development of achromatic full-field hard x-ray microscopy with two monolithic imaging mirrors

    NASA Astrophysics Data System (ADS)

    Matsuyama, S.; Kino, H.; Yasuda, S.; Kohmura, Y.; Okada, H.; Ishikawa, T.; Yamauchi, K.

    2015-09-01

    Advanced Kirkpatrick-Baez mirror optics using two monolithic imaging mirrors was developed to realize an achromatic, high-resolution, and a high-stability full-field X-ray microscope. The mirror consists of an elliptical section and a hyperbolic section on a quartz glass substrate, in which the geometry follows the Wolter (type I) optics rules. A preliminary test was performed at SPring-8 using X-rays monochromatized to 9.881 keV. A 100-nm feature on a Siemens star chart could be clearly observed.

  20. Demonstration of achromatic cold-neutron microscope utilizing axisymmetric focusing mirrors

    SciTech Connect

    Liu, D.; Khaykovich, B.; Hussey, D.; Jacobson, D.; Arif, M.; Gubarev, M. V.; Ramsey, B. D.; Moncton, D. E.

    2013-05-06

    An achromatic cold-neutron microscope with magnification 4 is demonstrated. The image-forming optics is composed of nested coaxial mirrors of full figures of revolution, so-called Wolter optics. The spatial resolution, field of view, and depth of focus are measured and found consistent with ray-tracing simulations. Methods of increasing the resolution and magnification are discussed, as well as the scientific case for the neutron microscope. In contrast to traditional pinhole-camera neutron imaging, the resolution of the microscope is determined by the mirrors rather than by the collimation of the beam, leading to possible dramatic improvements in the signal rate and resolution.

  1. Achromatic parvocellular contrast gain in normal and color defective observers: Implications for the evolution of color vision.

    PubMed

    Lutze, Margaret; Pokorny, Joel; Smith, Vivianne C

    2006-01-01

    The PC pathway conveys both chromatic and achromatic information, with PC neurons being more responsive to chromatic (L-M) than to achromatic (L+M) stimuli. In considering the evolution of color vision, it has been suggested that the dynamic range of chromatic PC-pathway processing is tuned to the chromatic content of the natural environment. Anomalous trichromats, with reduced separation of their L- and M-cone spectral sensitivities, have diminished chromatic input to PC-pathway cells. Dichromats, with absent L or M cones, should have no chromatic input to PC-pathway cells. Therefore, the PC-pathway dynamic range of color defectives should be released from any constraint imposed by the chromatic environment. Here we ask whether this results in compensatory enhancement of achromatic PC-pathway processing in color defectives. This study employed a psychophysical method designed to isolate PC-pathway processing using achromatic stimuli. In a pulsed-pedestal condition, a four-square stimulus array appeared within a uniform surround. During a trial, one of the test squares differed from the other three, and the observer's task was to choose the square that was different. A four-alternative, forced-choice method was used to determine thresholds as a function of the contrast of the four-square array to the surround. Seven color defective and four normal observers participated. Results showed no systematic differences between normals and color defectives. There was no enhancement of achromatic processing as compensation for reduced chromatic processing in the PC-pathway system in color defectives. From physiological recordings, PC-pathway achromatic contrast gains of dichromatic and trichromatic New World primates and trichromatic Old World macaques have also been shown to be similar to each other. Our study and the animal studies imply that PC-pathway contrast gain parameters were regulated by factors other than the environmental chromaticity gamut, and may have arisen

  2. Achromatic and high-resolution full-field X-ray microscopy based on total-reflection mirrors.

    PubMed

    Matsuyama, Satoshi; Emi, Yoji; Kino, Hidetoshi; Kohmura, Yoshiki; Yabashi, Makina; Ishikawa, Tetsuya; Yamauchi, Kazuto

    2015-04-20

    We developed an achromatic and high-resolution full-field X-ray microscope based on advanced Kirkpatrick-Baez mirror optics that comprises two pairs of elliptical mirrors and hyperbolic mirrors utilizing the total reflection of X-rays. Performance tests to investigate the spatial resolution and chromatic aberration were performed at SPring-8. The microscope clearly resolved the pattern with ~100-nm feature size. Imaging the pattern by changing the X-ray energy revealed achromatism in the wide energy range of 8-11 keV.

  3. The male blue crab, Callinectes sapidus, uses both chromatic and achromatic cues during mate choice.

    PubMed

    Baldwin, Jamie; Johnsen, Sönke

    2012-04-01

    In the blue crab, Callinectes sapidus, claw color varies by sex, sexual maturity and individual. Males rely in part on color cues to select appropriate mates, and these chromatic cues may be perceived through an opponent interaction between two photoreceptors with maximum wavelength sensitivities at 440 and 508 nm. The range of color discrimination of this dichromatic visual system may be limited, however, and it is unclear whether male blue crabs are capable of discriminating the natural variations in claw color that may be important in mate choice. By testing males' innate color preferences in binary choice tests between photographs of red-clawed females and six variations of orange-clawed females, we examined both the chromatic (opponent interaction) and achromatic (relative luminance) cues used in male mate choice. Males significantly preferred red-clawed females to orange-clawed females, except when the test colors were similar in both opponency and relative luminance. Our results are unusual in that they indicate that male mate choice in the blue crab is not guided solely by achromatic or chromatic mechanisms, suggesting that both color and intensity are used to evaluate female claw color.

  4. The nature of the late achromatic bump in GRB 120326A

    NASA Astrophysics Data System (ADS)

    Melandri, A.; Virgili, F. J.; Guidorzi, C.; Bernardini, M. G.; Kobayashi, S.; Mundell, C. G.; Gomboc, A.; Dintinjana, B.; Hentunen, V.-P.; Japelj, J.; Kopač, D.; Kuroda, D.; Morgan, A. N.; Steele, I. A.; Quadri, U.; Arici, G.; Arnold, D.; Girelli, R.; Hanayama, H.; Kawai, N.; Mikuž, H.; Nissinen, M.; Salmi, T.; Smith, R. J.; Strabla, L.; Tonincelli, M.; Quadri, A.

    2014-12-01

    The long Swift gamma-ray burst GRB 120326A at redshift z = 1.798 exhibited a multi-band light-curve with a striking feature: a late-time, long-lasting achromatic rebrightening that is rarely seen in such events. Peaking in optical and X-ray bands ~35 ks (~12.5 ks in the GRB rest frame) after the 70 s GRB prompt burst, the feature brightened nearly two orders of magnitude above the underlying optical power-law decay. By modelling the multi-wavelength light-curves, we investigated possible causes of the rebrightening in the context of the standard fireball model. We excluded a range of scenarios for the origin of this feature: reverse-shock flash, late-time forward-shock peak caused by the passage of the brightest synchrotron frequency through the optical band, late central engine optical or X-ray flares, interaction between the expanding blast wave and a density enhancement in the circumburst medium, and gravitational microlensing. Instead we conclude that the achromatic rebrightening may be caused by a refreshed forward shock or a geometrical effect. In addition, we identify an additional component after the end of the prompt emission, which shapes the observed X-ray and optical light-curves differently, and which rules out a single overall emission component to explain the observed early-time emission.

  5. Achromatic and chromatic sensation as a function of color temperature and retinal illuminance.

    PubMed

    Sternheim, C E; Drum, B

    1993-05-01

    Changes in color appearance with retinal illuminance were studied by scaling the achromatic, yellow, and blue sensation components for test lights with color temperatures from 3041 to 8650 K at 4.10, 2.18, and 0.33 log Td. At 4.10 log Td two observers showed similar pure whites (4823 and 5258 K) and narrow transition zones (1502 and 969 K) from yellow to blue chromatic response categories. The relative amounts of yellow, blue, and white varied with color temperature in a similar manner for both observers. One observer maintained similar absolute whites and transition zones for all illuminances. For the second observer the transition zone broadened and shifted to higher color temperatures as illuminance decreased. At color temperatures both above and below the transition zone chromatic saturation was greatest at the intermediate illuminance. The loss of saturation at 0.33 and 4.10 log Td is consistent with the observation that as the illuminance of a spectral color is raised above threshold, saturation increases to a maximum and then falls. Our findings reinforce the notion that at relatively low illuminances chromatic responses increase with increasing illuminance more rapidly than achromatic responses and that the opposite is true at high illuminances.

  6. The proximity structure of achromatic surface colors and the impossibility of asymmetric lightness matching.

    PubMed

    Logvinenko, Alexander D; Maloney, Laurence T

    2006-01-01

    In asymmetric lightness matching tasks, observers sometimes report that they cannot achieve satisfactory matches between achromatic surfaces under different neutral illuminants. The surfaces appear different, yet no further adjustment of either surface improves the match. There are evident difficulties in interpreting data from a task that the observer cannot always do, and these difficulties likely affect the interpretation of a large number of previous studies. We investigated, as an alternative to asymmetric matching, the direct use of proximity judgments in the study of surface lightness perception. We asked observers to rate the perceived dissimilarity of pairs of achromatic surfaces that were placed in identical scenes and viewed under different neutral illuminants. We develop a parametric model that accurately predicts perceived dissimilarity in terms of physical light intensities and surface albedos. The parameters of this model are readily interpretable. In particular, the ratio of the influence of changes in illuminant intensity and changes in surface albedo is a measure of the extent to which the observer discounts the illuminant. Asymmetric lightness matching can be interpreted as an unachievable limiting case of proximity judgment. PMID:16617831

  7. Effect of chromatic adaptation on the achromatic locus: the role of contrast, luminance and background color.

    PubMed

    Werner, J S; Walraven, J

    1982-01-01

    Two superposed annular test lights of complementary spectral composition were presented as 60-90' incremental test flashes on 480' steady backgrounds. Two observers adjusted the ratio of the two test lights to maintain an achromatic appearance under conditions of adaptation that varied with respect to background luminance, chromaticity and stimulus contrast. The shift in chromaticity of the achromatic point was in the direction of the chromaticity of the background, while the magnitude of the shift increased as an increasing function of background luminance and as a decreasing function of contrast. These data confirm and extend a model of chromatic adaptation that has the following properties: (1) non-additivity of transient test and steady background fields, in the sense that the background, although physically adding to the test flash, only affects its hue by way of altering the gain of cone pathways; (2) Vos-Walraven cone spectral sensitivities; and (3) adaptation sites in the cone pathways having the same action spectra as Stiles' pi 5, pi 4 and (modified) pi 1 mechanisms, and which generate receptor-specific attenuation factors (von Kries Coefficients) according to Stiles' generalized threshold vs intensity function, zeta (x).

  8. Measurements of achromatic and chromatic contrast sensitivity functions for an extended range of adaptation luminance

    NASA Astrophysics Data System (ADS)

    Kim, Kil Joong; Mantiuk, Rafal; Lee, Kyoung Ho

    2013-03-01

    Inspired by the ModelFest and ColorFest data sets, a contrast sensitivity function was measured for a wide range of adapting luminance levels. The measurements were motivated by the need to collect visual performance data for natural viewing of static images at a broad range of luminance levels, such as can be found in the case of high dynamic range displays. The detection of sine-gratings with Gaussian envelope was measured for achromatic color axis (black to white), two chromatic axes (green to red and yellow-green to violet) and two mixed chromatic and achromatic axes (dark-green to light-pink, and dark yellow to light-blue). The background luminance varied from 0.02 to 200 cd/m2. The spatial frequency of the gratings varied from 0.125 to 16 cycles per degree. More than four observers participated in the experiments and they individually determined the detection threshold for each stimulus using at least 20 trials of the QUEST method. As compared to the popular CSF models, we observed higher sensitivity drop for higher frequencies and significant differences in sensitivities in the luminance range between 0.02 and 2 cd/m2. Our measurements for chromatic CSF show a significant drop in sensitivity with luminance, but little change in the shape of the CSF. The drop of sensitivity at high frequencies is significantly weaker than reported in other studies and assumed in most chromatic CSF models.

  9. Evaluation of wavelength shifters for spectral separation of barium fluoride emissions

    SciTech Connect

    DeVol, T.A.

    1993-10-01

    BaF{sub 2} has the advantage over other scintillators, when comparing radiation hardness, scintillation decay time, and fast scintillation yield. Since the fast BaF{sub 2} emissions have peak wavelengths of 220, 195, and 170 nm, a wavelength shifter (WLS) is needed. Organic fluors were evaluated as WLS components. Results indicate that spectral separation using WLS is possible, but not to the extent desired; other techniques must be used also. Alternative scintillators, such as CeF{sub 3}, should be investigated.

  10. Evaluation of the range shifter model for proton pencil-beam scanning for the Eclipse v.11 treatment planning system.

    PubMed

    Matysiak, Witold; Yeung, Daniel; Slopsema, Roelf; Li, Zuofeng

    2016-03-08

    Existing proton therapy pencil-beam scanning (PBS) systems have limitations on the minimum range to which a patient can be treated. This limitation arises from practical considerations, such as beam current intensity, layer spacing, and delivery time. The range shifter (RS) - a slab of stopping material inserted between the nozzle and the patient - is used to reduce the residual range of the incident beam so that the treatment ranges can be extended to shallow depths. Accurate modeling of the RS allows one to calculate the beam spot size entering the patient, given the proton energy, for arbitrary positions and thicknesses of the RS in the beam path. The Eclipse version 11 (v11) treatment planning system (TPS) models RS-induced beam widening by incorporating the scattering properties of the RS material into the V-parameter. Monte Carlo simulations with Geant4 code and analytical calculations using the Fermi-Eyges (FE) theory with Highland approximation of multiple Coulomb scattering (MCS) were employed to calculate proton beam widening due to scattering in the RS. We demonstrated that both methods achieved consistent results and could be used as a benchmark for evaluating the Eclipse V-parameter model. In most cases, the V-parameter model correctly predicted the beam spot size after traversing the RS. However, Eclipse did not enforce the constraint for a nonnegative covariance matrix when fitting the spot sizes to derive the phase space parameters, which resulted in incorrect calculations under specific conditions. In addition, Eclipse v11 incorrectly imposed limits on the individual values of the phase space parameters, which could lead to incorrect spot size values in the air calculated for beams with spot sigmas <3.8 mm. Notably, the TPS supplier (Varian) and hardware vendor (Ion Beam Applications) inconsistently refer to the RS position, which may result in improper spot size calculations.

  11. Evaluation of the range shifter model for proton pencil-beam scanning for the Eclipse v.11 treatment planning system.

    PubMed

    Matysiak, Witold; Yeung, Daniel; Slopsema, Roelf; Li, Zuofeng

    2016-01-01

    Existing proton therapy pencil-beam scanning (PBS) systems have limitations on the minimum range to which a patient can be treated. This limitation arises from practical considerations, such as beam current intensity, layer spacing, and delivery time. The range shifter (RS) - a slab of stopping material inserted between the nozzle and the patient - is used to reduce the residual range of the incident beam so that the treatment ranges can be extended to shallow depths. Accurate modeling of the RS allows one to calculate the beam spot size entering the patient, given the proton energy, for arbitrary positions and thicknesses of the RS in the beam path. The Eclipse version 11 (v11) treatment planning system (TPS) models RS-induced beam widening by incorporating the scattering properties of the RS material into the V-parameter. Monte Carlo simulations with Geant4 code and analytical calculations using the Fermi-Eyges (FE) theory with Highland approximation of multiple Coulomb scattering (MCS) were employed to calculate proton beam widening due to scattering in the RS. We demonstrated that both methods achieved consistent results and could be used as a benchmark for evaluating the Eclipse V-parameter model. In most cases, the V-parameter model correctly predicted the beam spot size after traversing the RS. However, Eclipse did not enforce the constraint for a nonnegative covariance matrix when fitting the spot sizes to derive the phase space parameters, which resulted in incorrect calculations under specific conditions. In addition, Eclipse v11 incorrectly imposed limits on the individual values of the phase space parameters, which could lead to incorrect spot size values in the air calculated for beams with spot sigmas <3.8 mm. Notably, the TPS supplier (Varian) and hardware vendor (Ion Beam Applications) inconsistently refer to the RS position, which may result in improper spot size calculations. PMID:27074461

  12. The Role of Contrast in the Perception of Achromatic Transparency: Comment on Singh and Anderson (2002) and Anderson (2003)

    ERIC Educational Resources Information Center

    Albert, Marc K.

    2008-01-01

    M. Singh and B. L. Anderson proposed a perceptual theory of achromatic transparency in which the perceived transmittance of a perceived transparent filter is determined by the ratio of the Michelson contrast seen in the region of transparency to that of the background seen directly. Subsequently, B. L. Anderson, M. Singh, and J. Meng proposed that…

  13. Electronically controlled optical beam-steering by an active phased array of metallic nanoantennas.

    PubMed

    DeRose, C T; Kekatpure, R D; Trotter, D C; Starbuck, A; Wendt, J R; Yaacobi, A; Watts, M R; Chettiar, U; Engheta, N; Davids, P S

    2013-02-25

    An optical phased array of nanoantenna fabricated in a CMOS compatible silicon photonics process is presented. The optical phased array is fed by low loss silicon waveguides with integrated ohmic thermo-optic phase shifters capable of 2π phase shift with ∼ 15 mW of applied electrical power. By controlling the electrical power to the individual integrated phase shifters fixed wavelength steering of the beam emitted normal to the surface of the wafer of 8° is demonstrated for 1 × 8 phased arrays with periods of both 6 and 9 μm. PMID:23482053

  14. Full complex spectrum simultaneous obtaining SD-OCT

    NASA Astrophysics Data System (ADS)

    Gelikonov, Grigory V.; Gelikonov, Valentin M.; Shilyagin, Pavel A.

    2011-03-01

    An efficient technique of simultaneous obtaining of quadrature spectral components of interference signal in spectrometer-based OCT is proposed. The components are obtained in air-spaced non-polarization interferometer by partition of reference beam onto two parts and using an achromatic phase shifter. Several setups of phase sifter are described and compared.

  15. Sector Shifters.

    ERIC Educational Resources Information Center

    Natale, Jo Anna

    1994-01-01

    Several superintendents have recently left school administration for careers in private education companies such as Education Alternatives, Inc., the Edison Project, and Sylvan Learning Systems, Inc. Former superintendents from New York, Rochester, Saint Paul, and Detroit reflect on their reasons for switching careers. Salary considerations…

  16. Lens design for a white-light cosine-transform achromat.

    PubMed

    Farr, K B; Wang, S G

    1995-01-01

    We describe the lens design for a twin-imaging white-light interferometer in which the interference pattern at the exit-pupil plane is the cosine transform of the spatial-intensity distribution of the object. The achromatic condition in terms of optical power is derived. The analysis of the transform aberration shows that the even aberrations, e.g., spherical aberration and field curvature, do not degrade the cosine transform and need not be corrected. This significant simplification permits us to design systems with good performance and uncomplicated lens structures. We present a lens design with three elements and a length of 320 mm. The system is capable of resolving more than 10(6) pixels with an operating spectral bandwidth of 100 nm. The results of an experiment with an early four-element design are also presented.

  17. ACHROMATIC LOW-BETA INTERACTION REGION DESIGN FOR AN ELECTRON-ION COLLIDER

    SciTech Connect

    Vasiliy Morozov, Yaroslav Derbenev

    2011-09-01

    An achromatic Interaction Region (IR) design concept is presented with an emphasis on its application at an electron-ion collider. A specially-designed symmetric Chromaticity Compensation Block (CCB) induces an angle spread in the passing beam such that it cancels the chromatic kick of the final focusing quadrupoles. Two such CCB's placed symmetrically around an interaction point (IP) allow simultaneous compensation of the 1st-order chromaticities and chromatic beam smear at the IP without inducing significant 2nd-order aberrations. Special attention is paid to the difference in the electron and ion IR design requirements. We discuss geometric matching of the electron and ion IR footprints. We investigate limitations on the momentum acceptance in this IR design.

  18. Achromatic flat optical components via compensation between structure and material dispersions

    PubMed Central

    Li, Yang; Li, Xiong; Pu, Mingbo; Zhao, Zeyu; Ma, Xiaoliang; Wang, Yanqin; Luo, Xiangang

    2016-01-01

    Chromatism causes great quality degradation of the imaging system, especially for diffraction imaging. The most commonly method to overcome chromatism is refractive/diffractive hybrid optical system which, however, sacrifices the light weight and integration property of diffraction elements. A method through compensation between the structure dispersion and material dispersion is proposed to overcome the chromatism in flat integrated optical components. This method is demonstrated by making use of silver nano-slits waveguides to supply structure dispersion of surface plasmon polaritons (SPP) in metal-insulator-metal (MIM) waveguide to compensate the material dispersion of metal. A broadband deflector and lens are designed to prove the achromatic property of this method. The method demonstrated here may serve as a solution of broadband light manipulation in flat integrated optical systems. PMID:26794855

  19. Two-stage reflective optical system for achromatic 10 nm x-ray focusing

    NASA Astrophysics Data System (ADS)

    Motoyama, Hiroto; Mimura, Hidekazu

    2015-12-01

    Recently, coherent x-ray sources have promoted developments of optical systems for focusing, imaging, and interferometers. In this paper, we propose a two-stage focusing optical system with the goal of achromatically focusing pulses from an x-ray free-electron laser (XFEL), with a focal width of 10 nm. In this optical system, the x-ray beam is expanded by a grazing-incidence aspheric mirror, and it is focused by a mirror that is shaped as a solid of revolution. We describe the design procedure and discuss the theoretical focusing performance. In theory, soft-XFEL lights can be focused to a 10 nm area without chromatic aberration and with high reflectivity; this creates an unprecedented power density of 1020 W cm-2 in the soft-x-ray range.

  20. The achromatic design of an atmospheric dispersion corrector for extremely large telescopes.

    PubMed

    Bahrami, Mehdi; Goncharov, Alexander V

    2011-08-29

    For off-zenith observations with ground-based astronomical telescopes, the effect of atmospheric dispersion relative to diffraction on image size increases with telescope diameter. Correction of atmospheric dispersion in extremely large telescopes (ELTs) might become critical. A common solution for ELTs is to use linear atmospheric dispersion correctors (ADCs). In spite of their simplicity, the intrinsic chromatic aberrations of linear ADCs could render diffraction-limited imaging impossible when used in a fast focus. The chromatic problems of the linear ADC in ELTs can be resolved by replacing the linear ADC by the achromatic ADC designs presented here, which provide diffraction-limited image quality and offer several opto-mechanical advantages over linear ADCs.

  1. Signals for color and achromatic contrast in the goldfish inner retina.

    PubMed

    Burkhardt, Dwight A

    2014-11-01

    A moving stimulus paradigm was designed to investigate color contrast encoding in the retina. Recently, this paradigm yielded suggestive evidence for color contrast encoding in zebrafish but the significance and generality remain uncertain since the properties of color coding in the zebrafish inner retina are largely unknown. Here, the question of color contrast is pursued in the goldfish retina where there is much accumulated evidence for retinal mechanisms of color vision and opponent color-coding, in particular. Recordings of a sensitive local field potential of the inner retina, the proximal negative response, were made in the intact, superfused retina in the light-adapted state. Responses to color contrast and achromatic contrast were analyzed by comparing responses to a green moving bar on green versus red backgrounds. The quantitative form of the irradiance/response curves was distinctly different under a range of conditions in 32 retinas, thereby providing robust evidence for red-green color contrast. The color contrast is based on successive contrast, occurs in the absence of overt color opponency, and clearly differs from previous findings in the goldfish retina for simultaneous color contrast mediated by color-opponent neurons. The form of the irradiance/response curves suggests that successive color contrast is particularly important when achromatic contrast is low, as often occurs in natural environments. The present results provide a parallel with the well-known principle of human color vision, first proposed by Kirschmann as the third law of color contrast, and may also have implications for the evolution of vertebrate color vision.

  2. Active membrane phased array radar

    NASA Technical Reports Server (NTRS)

    Moussessian, Alina; Del Castillo, Linda; Huang, John; Sadowy, Greg; Hoffman, James; Smith, Phil; Hatake, Toshiro; Derksen, Chuck; Lopez, Bernardo; Caro, Ed

    2005-01-01

    We have developed the first membrane-based active phased array in L-band (1.26GHz). The array uses membrane compatible Transmit/Receive (T/R) modules (membrane T/R) for each antenna element. We use phase shifters within each T/R module for electronic beam steering. We will discuss the T/R module design and integration with the membrane, We will also present transmit and receive beam-steering results for the array.

  3. Achromatic parvocellular contrast gain in normal and color defective observers: Implications for the evolution of color vision.

    PubMed

    Lutze, Margaret; Pokorny, Joel; Smith, Vivianne C

    2006-01-01

    The PC pathway conveys both chromatic and achromatic information, with PC neurons being more responsive to chromatic (L-M) than to achromatic (L+M) stimuli. In considering the evolution of color vision, it has been suggested that the dynamic range of chromatic PC-pathway processing is tuned to the chromatic content of the natural environment. Anomalous trichromats, with reduced separation of their L- and M-cone spectral sensitivities, have diminished chromatic input to PC-pathway cells. Dichromats, with absent L or M cones, should have no chromatic input to PC-pathway cells. Therefore, the PC-pathway dynamic range of color defectives should be released from any constraint imposed by the chromatic environment. Here we ask whether this results in compensatory enhancement of achromatic PC-pathway processing in color defectives. This study employed a psychophysical method designed to isolate PC-pathway processing using achromatic stimuli. In a pulsed-pedestal condition, a four-square stimulus array appeared within a uniform surround. During a trial, one of the test squares differed from the other three, and the observer's task was to choose the square that was different. A four-alternative, forced-choice method was used to determine thresholds as a function of the contrast of the four-square array to the surround. Seven color defective and four normal observers participated. Results showed no systematic differences between normals and color defectives. There was no enhancement of achromatic processing as compensation for reduced chromatic processing in the PC-pathway system in color defectives. From physiological recordings, PC-pathway achromatic contrast gains of dichromatic and trichromatic New World primates and trichromatic Old World macaques have also been shown to be similar to each other. Our study and the animal studies imply that PC-pathway contrast gain parameters were regulated by factors other than the environmental chromaticity gamut, and may have arisen

  4. Optical heterodyne micro-vibration measurement based on all-fiber acousto-optic frequency shifter.

    PubMed

    Zhang, Wending; Gao, Wei; Huang, Ligang; Mao, Dong; Jiang, Biqiang; Gao, Feng; Yang, Dexing; Zhang, Guoquan; Xu, Jingjun; Zhao, Jianlin

    2015-06-29

    An all-fiber optical heterodyne detection configuration was proposed based on an all-fiber acousto-optic structure, which acted as both frequency shifter and coupler at the same time. The vibration waveform within a frequency range between 1 Hz to 200 kHz of a piezoelectric mirror was measured using this optical heterodyne detection system. The minimal measurable vibration amplitude and resolution are around 6 pm and 1 pm in the region of tens to hundreds of kilohertz, respectively. The configuration has advantages of compact size, high accuracy and non-contact measurement. Moreover, it is of a dynamically adjustable signal-to-noise ratio to adapt different surface with different reflections in the measurement, which will improve the usage efficiency of the light power. PMID:26191765

  5. Design of a triple-bend isochronous achromat with minimum coherent-synchrotron-radiation-induced emittance growth

    NASA Astrophysics Data System (ADS)

    Venturini, M.

    2016-06-01

    Using a 1D steady-state free-space coherent synchrotron radiation (CSR) model, we identify a special design setting for a triple-bend isochronous achromat that yields vanishing emittance growth from CSR. When a more refined CSR model with transient effects is included in the analysis, numerical simulations show that the main effect of the transients is to shift the emittance growth minimum slightly, with the minimum changing only modestly.

  6. V-band pseudomorphic HEMT MMIC phased array components for space communications

    NASA Technical Reports Server (NTRS)

    Lan, G. L.; Pao, C. K.; Wu, C. S.; Hu, M.; Downey, Alan N.

    1992-01-01

    Recent advances in pseudomorphic high-electron-mobility transistor (PMHEMT) monolithic microwave integrated circuit (MMIC) technology have made it the preferred candidate for high performance millimeter-wave components for phased array applications. The development of V-band PMHEMT/MMIC components including power amplifiers and phase shifters is described. For the single-stage MMIC power amplifier employing a 200 micron PMHEMT, we achieved 151.4 mW output power (757.0 mW/mm) with 1.8 dB associated gain and 26.4 percent power-added efficiency at 60 GHz. A two-stage MMIC amplifier utilizing the same devices demonstrated small-signal gain as high as 15 dB at 58 GHz. And, for the phase shifter, a four-bit phase shifter with less than 8 dB insertion loss from 61 to 63 GHz was measured.

  7. Design of a multi-bend achromat lattice for 3 GeV synchrotron light source

    NASA Astrophysics Data System (ADS)

    Kim, Eun-San

    2016-03-01

    We present a lattice design for a low-emittance and high-brilliance 3 GeV synchrotron light source that has been widely investigated in the world. We show the design results for a MBA (Multi-Bend Achromat) lattice with an emittance of 1.3 nm and 282.4 m circumference. Each cell has 5 bending magnets that consist of outer two with bending angle of 4.5° and inner three with bending angle of 7°. The lattice is designed to be flexible and consists of 12 straight sections in which one straight section has a length of 5.9 m. We have studied the dynamic aperture in the lattice with machine errors. It is shown that the designed low-emittance lattice provides sufficient dynamic aperture after COD correction. We present the results of variations of emittance, energy spread and dynamic aperture due to in-vacuum undulators in the straight sections. We performed particle tracking after the beam injection to investigate the efficiency of the injection scheme. We show the designed results of an injection scheme that shows the space allocation in injection section and the particle motions of injected beam. Our designed lattice provides a good optimization in terms of the emittance and brilliance as a light source for 3 GeV energy and circumference of 28 m.

  8. Needle-based fluorescence endomicroscopy via structured illumination with a plastic, achromatic objective

    PubMed Central

    Kyrish, Matthew; Dobbs, Jessica; Jain, Shalini; Wang, Xiao; Yu, Dihua; Richards-Kortum, Rebecca

    2013-01-01

    Abstract. In order to diagnose cancer, a sample must be removed, prepared, and examined under a microscope, which is expensive, invasive, and time consuming. Fiber optic fluorescence endomicroscopy, where an image guide is used to obtain high-resolution images of tissue in vivo, has shown promise as an alternative to conventional biopsies. However, the resolution of standard endomicroscopy is limited by the fiber bundle sampling frequency and out-of-focus light. A system is presented which incorporates a plastic, achromatic objective to increase the sampling and which provides optical sectioning via structured illumination to reject background light. An image is relayed from the sample by a fiber bundle with the custom 2.1-mm outer diameter objective lens integrated to the distal tip. The objective is corrected for the excitation and the emission wavelengths of proflavine (452 and 515 nm). It magnifies the object onto the fiber bundle to improve the system’s lateral resolution by increasing the sampling. The plastic lenses were fabricated via single-point diamond turning and assembled using a zero alignment technique. Ex vivo images of normal and neoplastic murine mammary tissues stained with proflavine are captured. The system achieves higher contrast and resolves smaller features than standard fluorescence endomicroscopy. PMID:24002190

  9. Reduction of Beam Emittance of Pep-X Using Quadruple Bend Achromat Cell

    SciTech Connect

    Wang, Min-Huey; Cai, Yunhai; Hettel, Robert; Nosochkov, Yuri; /SLAC

    2009-05-26

    SLAC National Accelerator Laboratory is studying an option of building a high brightness synchrotron light source machine, PEP-X, in the existing PEP-II tunnel [1, 2]. By replacing 6 arcs of FODO cells of PEPII High Energy Ring (HER) with two arcs of DBA and four arcs of TME and installation of 89.3 m long damping wiggler an ultra low beam emittance of 0.14 nm-rad (including intra-beam scattering) at 4.5 GeV is achieved. In this paper we study the possibility to further reduce the beam emittance by releasing the constraint of the dispersion free in the DBA straight. The QBA (Quadruple Bend Achromat) cell is used to replace the DBA. The ratio of outer and inner bending angle is optimized. The dispersion function in the non-dispersion straight is controlled to compromise with lower emittance and beam size at the dispersion straight. An undulator of period length 23 mm, maximum magnetic field of 1.053 T, and total periods of 150 is used to put in the 30 straights to simulate the effects of these IDs on the beam emittance and energy spread. The brightness including all the ID effects is calculated and compared to the original PEP-X design.

  10. Plasmonic Color-Graded Nanosystems with Achromatic Subwavelength Architectures for Light Filtering and Advanced SERS Detection.

    PubMed

    Proietti Zaccaria, Remo; Bisio, Francesco; Das, Gobind; Maidecchi, Giulia; Caminale, Michael; Vu, Chinh Duc; De Angelis, Francesco; Di Fabrizio, Enzo; Toma, Andrea; Canepa, Maurizio

    2016-03-01

    Plasmonic color-graded systems are devices featuring a spatially variable plasmonic response over their surface. They are widely used as nanoscale color filters; their typical size is small enough to allow integration with miniaturized electronic circuits, paving the way to realize novel nanophotonic devices. Currently, most plasmonic color-graded systems are intrinsically discrete because their chromatic response exploits the tailored plasmon resonance of microarchitectures characterized by different size or geometry for each target color. Here, we report the realization of multifunctional plasmon-graded devices where continuously graded chromatic response is achieved by smoothly tuning the composition of the resonator material while simultaneously maintaining an achromatic nanoscale geometry. The result is a new class of versatile materials: we show their application as plasmonic filters with a potential pixel size smaller than half of the exciting wavelength but also as multiplexed surface-enhanced Raman spectroscopy (SERS) substrates. Many more implementations, such as photovoltaic efficiency boosters or color routers, await and will benefit from the low fabrication cost and intrinsic plasmonic flexibility of the presented systems. PMID:26959970

  11. Achromatic nested Kirkpatrick-Baez mirror optics for hard x-ray nanofocusing.

    SciTech Connect

    Liu, W.; Ice, G. E.; Assoufid, L.; Liu, C.; Shi, B.; Khachatryan, R.; Qian, J.; Zschack, P.; Tischler, J. Z.; Choi, J.-Y.

    2011-07-01

    The first test of nanoscale-focusing Kirkpatrick-Baez (KB) mirrors in the nested (or Montel) configuration used at a hard X-ray synchrotron beamline is reported. The two mirrors are both 40 mm long and coated with Pt to produce a focal length of 60 mm at 3 mrad incident angle, and collect up to a 120 {micro}m by 120 {micro}m incident X-ray beam with maximum angular acceptance of 2 mrad and a broad bandwidth of energies up to 30 keV. In an initial test a focal spot of about 150 nm in both horizontal and vertical directions was achieved with either polychromatic or monochromatic beam. The nested mirror geometry, with two mirrors mounted side-by-side and perpendicular to each other, is significantly more compact and provides higher demagnification than the traditional sequential KB mirror arrangement. Ultimately, nested mirrors can focus larger divergence to improve the diffraction limit of achromatic optics. A major challenge with the fabrication of the required mirrors is the need for near-perfect mirror surfaces near the edge of at least one of the mirrors. Special polishing procedures and surface profile coating were used to preserve the mirror surface quality at the reflecting edge. Further developments aimed at achieving diffraction-limited focusing below 50 nm are underway.

  12. Achromatic Nested Kirkpatrick-Baez Mirror Optics for Hard X-ray Nanofocusing

    SciTech Connect

    Liu, Wenjun; Ice, Gene E; Assoufid, Lahsen; Liu, Chian; Shi, B.; Khachatryan, Ruben; Qian, J; Zshack, Dr Paul; Tischler, Jonathan Zachary; Choi, Jae-Young

    2011-01-01

    The first test of nanoscale-focusing Kirkpatrick-Baez (KB) mirrors in the nested (or Montel) configuration used at a hard X-ray synchrotron beamline is reported. The two mirrors are both 40 mm long and coated with Pt to produce a focal length of 60 mm at 3 mrad incident angle, and collect up to a 120 {micro}m by 120 {micro}m incident X-ray beam with maximum angular acceptance of 2 mrad and a broad bandwidth of energies up to 30 keV. In an initial test a focal spot of about 150 nm in both horizontal and vertical directions was achieved with either polychromatic or monochromatic beam. The nested mirror geometry, with two mirrors mounted side-by-side and perpendicular to each other, is significantly more compact and provides higher demagnification than the traditional sequential KB mirror arrangement. Ultimately, nested mirrors can focus larger divergence to improve the diffraction limit of achromatic optics. A major challenge with the fabrication of the required mirrors is the need for near-perfect mirror surfaces near the edge of at least one of the mirrors. Special polishing procedures and surface profile coating were used to preserve the mirror surface quality at the reflecting edge. Further developments aimed at achieving diffraction-limited focusing below 50 nm are underway.

  13. Achromatic nested Kirkpatrick-Baez mirror optics for hard X-ray nanofocusing.

    PubMed

    Liu, Wenjun; Ice, Gene E; Assoufid, Lahsen; Liu, Chian; Shi, Bing; Khachatryan, Ruben; Qian, Jun; Zschack, Paul; Tischler, Jonathan Z; Choi, J Y

    2011-07-01

    The first test of nanoscale-focusing Kirkpatrick-Baez (KB) mirrors in the nested (or Montel) configuration used at a hard X-ray synchrotron beamline is reported. The two mirrors are both 40 mm long and coated with Pt to produce a focal length of 60 mm at 3 mrad incident angle, and collect up to a 120 µm by 120 µm incident X-ray beam with maximum angular acceptance of 2 mrad and a broad bandwidth of energies up to 30 keV. In an initial test a focal spot of about 150 nm in both horizontal and vertical directions was achieved with either polychromatic or monochromatic beam. The nested mirror geometry, with two mirrors mounted side-by-side and perpendicular to each other, is significantly more compact and provides higher demagnification than the traditional sequential KB mirror arrangement. Ultimately, nested mirrors can focus larger divergence to improve the diffraction limit of achromatic optics. A major challenge with the fabrication of the required mirrors is the need for near-perfect mirror surfaces near the edge of at least one of the mirrors. Special polishing procedures and surface profile coating were used to preserve the mirror surface quality at the reflecting edge. Further developments aimed at achieving diffraction-limited focusing below 50 nm are underway.

  14. Digital halftoning methods for selectively partitioning error into achromatic and chromatic channels

    NASA Technical Reports Server (NTRS)

    Mulligan, Jeffrey B.

    1990-01-01

    A method is described for reducing the visibility of artifacts arising in the display of quantized color images on CRT displays. The method is based on the differential spatial sensitivity of the human visual system to chromatic and achromatic modulations. Because the visual system has the highest spatial and temporal acuity for the luminance component of an image, a technique which will reduce luminance artifacts at the expense of introducing high-frequency chromatic errors is sought. A method based on controlling the correlations between the quantization errors in the individual phosphor images is explored. The luminance component is greatest when the phosphor errors are positively correlated, and is minimized when the phosphor errors are negatively correlated. The greatest effect of the correlation is obtained when the intensity quantization step sizes of the individual phosphors have equal luminances. For the ordered dither algorithm, a version of the method can be implemented by simply inverting the matrix of thresholds for one of the color components.

  15. Avoidance of achromatic colours by bees provides a private niche for hummingbirds.

    PubMed

    Lunau, Klaus; Papiorek, Sarah; Eltz, Thomas; Sazima, Marlies

    2011-05-01

    That hummingbird-pollinated plants predominantly have red flowers has been known for decades, but well-investigated research studies are still rare. Preference tests have shown that hummingbirds do not have an innate preference for red colours. In addition, hummingbirds do not depend solely upon red flowers, because white-flowered hummingbird-pollinated plants are also common and temporarily abundant. Here we show that both white and red hummingbird-pollinated flowers differ from bee-pollinated flowers in their reflection properties for ultraviolet (UV) light. Hummingbird-pollinated red flowers are on average less UV reflective, and white hummingbird-pollinated flowers are more UV reflective than the same coloured bee-pollinated ones. In preference tests with artificial flowers, neotropical orchid bees prefer red UV-reflecting artificial flowers and white UV-nonreflecting flowers over red and white flowers with the opposite UV properties. By contrast, hummingbirds showed no preference for any colour in the same tests. Plotting floral colours and test stimuli into the honeybees' perceptual colour space suggests that the less attractive colours are achromatic for bees and therefore more difficult to detect against the background. This underlying colour preference in bees might provide hummingbirds with a private niche that is not attractive to bees.

  16. Needle endomicroscope with a plastic, achromatic objective to perform optical biopsies of breast tissue

    NASA Astrophysics Data System (ADS)

    Kyrish, Matthew; Dobbs, Jessica; Richards-Kortum, Rebecca; Tkaczyk, Tomasz

    2013-03-01

    In order to diagnose cancer in breast tissue, a sample must be removed, prepared, and examined under a microscope. To provide an alternative to conventional biopsies, an endomicroscope intended to perform optical biopsies is demonstrated. The system provides high resolution, high contrast images in real-time which could allow a diagnosis to be made during surgery without the need for tissue removal. Optical sectioning is achieved via structured illumination to reject out of focus light. An image is relayed between the sample plane and the imaging system by a coherent fiber bundle with an achromatized objective lens at the distal tip of the fiber bundle which is the diameter of a biopsy needle. The custom, plastic objective provides correction for both the excitation and emission wavelengths of proflavine (452 nm and 515 nm, respectively). It also magnifies the object onto the distal tip of the fiber bundle to increase lateral resolution. The lenses are composed of the optical plastics Zeonex E48R, PMMA, and polystyrene. The lenses are fabricated via single point diamond turning and assembled using a zero alignment technique. The lateral resolution and chromatic focal shift were measured and in vitro images of breast carcinoma cells stained with proflavine were captured. The optical biopsy system is able to achieve optical sectioning and to resolve smaller features than the current high resolution microendoscope.

  17. Nonimaging achromatic lens design for LED direct-lit backlight applications

    NASA Astrophysics Data System (ADS)

    Tsai, Meng-Che; Chen, Bo-Song; Lee, Tsung-Xian

    2014-09-01

    Nowadays, light emitting diodes (LEDs) have been widely used in backlight module for display technology. Most of researches tend to improve optical performance in specific applications, such as sufficient efficiency, desired intensity distribution and high illuminance uniformity. However, most of phosphor converted white LEDs have the problem of inducing impure white light. The undesired phenomenon of yellow ring or blue ring becomes more serious through incorrect secondary optical design. In this paper, we emphasize on enhancing the spatial color and illuminance uniformity of LED direct-lit backlight using nonimaging achromatic lens design. We propose a new design method to re-distribute and uniform the ratio of blue and yellow light on the target surface. Moreover, we further apply it in direct-lit LED backlight lens design, in which the uniformity of illuminance on the out coupling surface can be as much as 83.7% and the color uniformity triangleu'v') is improved to 0.0039. Therefore, the result of high color and illumination uniformity can be achieved simultaneously.

  18. Systolic architectures based on barrel shifters for real-time digital signal processing

    SciTech Connect

    Chen, T.

    1985-01-01

    The throughput in real-time digital signal processing applications is limited by both the capability of the processors employed for number-crunching operations and the capacity of a supporting communications link. The systolic architectures eliminate the memory bandwidth problems by allowing multiple computations for each memory access and result in a speed-up in the execution time of compute-bound computations. However, the throughput rate in a systolic array is still limited by the computational time needed for one basic cell, which is composed of a multiplier and an accumulator. The multiplier in the basic cell requires either a large chip area if high speed is desired, or a large amount of time if serial architecture is used. The use of barrel shifters as computational elements in systolic arrays was proposed and studied in detail in this thesis. In the new systolic arrays there are two different structures, parallel and cascaded, that can be used to implement FIR filters. A unique cascaded structure was developed in this study that is shown to have better performance and requires significantly less basic cells.

  19. Phased array-fed antenna configuration study: Technology assessment

    NASA Technical Reports Server (NTRS)

    Croswell, W. F.; Ball, D. E.; Taylor, R. C.

    1983-01-01

    Spacecraft array fed reflector antenna systems were assessed for particular application to a multiple fixed spot beam/multiple scanning spot beam system. Reflector optics systems are reviewed in addition to an investigation of the feasibility of the use of monolithic microwave integrated circuit power amplifiers and phase shifters in each element of the array feed.

  20. [Sensitivity and specificity of flicker perimetry with Pulsar. Comparison with achromatic (white-on-white) perimetry in glaucoma patients].

    PubMed

    Göbel, K; Erb, C

    2013-02-01

    The early detection of functional glaucoma damage plays an increasingly more central role in the diagnosis and treatment of glaucoma disease. Using selective perimetry detection of early glaucomatous defects is more likely and one of these methods is flicker perimetry with Pulsar. Flicker perimetry is used to analyze the temporal visual function in combination with spatial resolution and contrast sensitivity as opposed to standard automated perimetry which measures the differential light sensitivity with a non-specific stimulus. This study showed a higher sensitivity and specificity of Pulsar perimetry in comparison to achromatic perimetry in glaucoma patients.

  1. [Sensitivity and specificity of flicker perimetry with Pulsar. Comparison with achromatic (white-on-white) perimetry in glaucoma patients].

    PubMed

    Göbel, K; Erb, C

    2013-02-01

    The early detection of functional glaucoma damage plays an increasingly more central role in the diagnosis and treatment of glaucoma disease. Using selective perimetry detection of early glaucomatous defects is more likely and one of these methods is flicker perimetry with Pulsar. Flicker perimetry is used to analyze the temporal visual function in combination with spatial resolution and contrast sensitivity as opposed to standard automated perimetry which measures the differential light sensitivity with a non-specific stimulus. This study showed a higher sensitivity and specificity of Pulsar perimetry in comparison to achromatic perimetry in glaucoma patients. PMID:23338528

  2. The new LM-PCR/shifter method for the genotyping of microorganisms based on the use of a class IIS restriction enzyme and ligation mediated PCR.

    PubMed

    Krawczyk, Beata; Leibner-Ciszak, Justyna; Stojowska, Karolina; Kur, Józef

    2011-12-01

    This study details and examines a novel ligation-mediated polymerase chain reaction (LM-PCR) method. Named the LM-PCR/Shifter, it relies on the use of a Class IIS restriction enzyme giving restriction fragments with different 4-base, 5' overhangs, this being the Shifter, and the ligation of appropriate oligonucleotide adapters. A sequence of 4-base, 5' overhangs of the adapter and a 4- base sequence of the 3' end of the primer(s) determine a subset of the genomic restriction fragments, which are amplified by PCR. The method permits the differentiation of bacterial species strains on the basis of the different DNA band patterns obtained after electrophoresis in polyacrylamide gels stained with ethidium bromide and visualized in UV light. The usefulness of the LM-PCR/ Shifter method for genotyping is analyzed by a comparison with the restriction endonuclease analysis of chromosomal DNA by the pulsed-field gel electrophoresis (REA-PFGE) and PCR melting profile (PCR MP) methods for isolates of clinical origin. The clustering of the LM-PCR/Shifter fingerprinting data matched those of the REA-PFGE and PCR MP methods. We found that the LM-PCR/Shifter is rapid, and offers good discriminatory power and excellent reproducibility, making it a method that may be effectively applied in epidemiological studies.

  3. Source-Coupled, N-Channel, JFET-Based Digital Logic Gate Structure Using Resistive Level Shifters

    NASA Technical Reports Server (NTRS)

    Krasowski, Michael J.

    2011-01-01

    A circuit topography is used to create usable, digital logic gates using N (negatively doped) channel junction field effect transistors (JFETs), load resistors, level shifting resistors, and supply rails whose values are based on the DC parametric distributions of these JFETs. This method has direct application to the current state-of-the-art in high-temperature (300 to 500 C and higher) silicon carbide (SiC) device production, and defines an adaptation to the logic gate described in U.S. Patent 7,688,117 in that, by removing the level shifter from the output of the gate structure described in the patent (and applying it to the input of the same gate), a source-coupled gate topography is created. This structure allows for the construction AND/OR (sum of products) arrays that use far fewer transistors and resistors than the same array as constructed from the gates described in the aforementioned patent. This plays a central role when large multiplexer constructs are necessary; for example, as in the construction of memory. This innovation moves the resistive level shifter from the output of the basic gate structure to the front as if the input is now configured as what would be the output of the preceding gate, wherein the output is the two level shifting resistors. The output of this innovation can now be realized as the lone follower transistor with its source node as the gate output. Additionally, one may leave intact the resistive level shifter on the new gate topography. A source-coupled to direct-coupled logic translator will be the result.

  4. Frequency translation of light waves by propagation around an optical ring circuit containing a frequency shifter: II. Theoretical analysis.

    PubMed

    Shimizu, K; Horiguchi, T; Koyamada, Y

    1994-05-20

    Theoretical aspects of the frequency-translation ring circuit are considered through numerical simulations. We analyze the signal and noise propagation around an optical ring circuit that contains a frequency shifter, an erbium-doped fiber amplifier and a bandpass filter (BPF). The relations between the frequency-translation limit and some important parameters such as the BPF bandwidth and the polarization state are clarified. Numerical results for the frequency-translation limit are compared with reported experiments and a frequency translation of more than 100 GHz is predicted.

  5. Monolithically integrated enhancement/depletion-mode AlGaN/GaN HEMTs SRAM unit and voltage level shifter using fluorine plasma treatment

    NASA Astrophysics Data System (ADS)

    Yonghe, Chen; Xuefeng, Zheng; Jincheng, Zhang; Xiaohua, Ma; Yue, Hao

    2016-05-01

    A GaN-based E/D mode direct-couple logic 6 transistors SRAM unit and a voltage level shifter were designed and fabricated. E-mode and D-mode AlGaN/GaN HEMTs were integrated in one wafer using fluorine plasma treatment and using a moderate AlGaN barrier layer heterojunction structure. The 6 transistors SRAM unit consists of two symmetrical E/D mode inverters and two E-mode switch HEMTs. The output low and high voltage of the SRAM unit are 0.95 and 0.07 V at a voltage supply of 1 V. The voltage level shifter lowers the supply voltage using four Ni-AlGaN Schottky diodes in a series at a positive supply voltage of 6 V and a negative supply voltage of -6 V. By controlling the states of inverter modules of the level shifter in turn, the level shifter offers two channel voltage outputs of -0.5 and -5 V. The flip voltage of the level shifter is 0.76 V. Both the SRAM unit and voltage shifter operate correctly, demonstrating the promising potential for GaN-based E/D mode digital and analog integrated circuits. Several considerations are proposed to avoid the influence of threshold voltage degradation of D-mode and E-mode HEMT on the operation of the circuit. Project supported by the National Natural Science Foundation of China (No. 61334002), the Opening Project of Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory (No. ZHD201206), and the Program for New Century Excellent Talents in University (No. NCET-12-0915).

  6. Laser phase noise compensation in long-range OFDR by using an optical fiber delay loop

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Fan, Xinyu; Wang, Shuai; Yang, Guangyao; Liu, Qingwen; He, Zuyuan

    2016-04-01

    We propose and experimentally demonstrate a novel technique to compensate the laser phase noise in long-range OFDR by using an optical fiber delay loop, which mainly consists of a delay fiber and a frequency shifter. The delay fiber is used to shorten the optical path difference between two arms of the interferometer, and the frequency shifter works as a counter for taking the number of lightwave circulated in the loop. The preliminary experiment shows a successful compensation effect, and a 10 cm spatial resolution over 30 km measurement range is realized by using this method.

  7. Acoustic frequency combs for carrier-envelope phase stabilization.

    PubMed

    Borchers, Bastian; Lücking, Fabian; Steinmeyer, Günter

    2014-02-01

    A method for improved performance of feed-forward carrier-envelope phase stabilization in amplified laser sources is presented and experimentally demonstrated. The phase stabilization scheme is applicable for a broad range of repetition rates spanning from subhertz to 100 kHz. The method relies on driving an acousto-optic frequency shifter by few-cycle transients. The phase of these transients suitably controls the grating phase of the generated index grating inside the shifter material. This approach removes beam pointing as well as amplitude noise issues observed in continuously driven feed-forward schemes. The synthesis of these gratings can be understood as the acoustic equivalent of mode-locking or acoustic frequency combs. PMID:24487861

  8. Shielding Effects of a Building Structure on the Energy Deposit of Cosmic Rays in a Simple Wavelength Shifter-Based Scintillator

    ERIC Educational Resources Information Center

    Aiola, Salvatore; La Rocca, Paola; Riggi, Francesco; Riggi, Simone

    2012-01-01

    An experimental setup, based on a plastic scintillator with an embedded wavelength shifter fibre and photosensors at the two ends, has been used to detect cosmic muons in undergraduate laboratory activities. Time and amplitude information from the two photosensors were measured using the time-over-threshold technique. The distribution of the…

  9. What visual illusions tell us about underlying neural mechanisms and observer strategies for tackling the inverse problem of achromatic perception

    PubMed Central

    Blakeslee, Barbara; McCourt, Mark E.

    2015-01-01

    Research in lightness perception centers on understanding the prior assumptions and processing strategies the visual system uses to parse the retinal intensity distribution (the proximal stimulus) into the surface reflectance and illumination components of the scene (the distal stimulus—ground truth). It is agreed that the visual system must compare different regions of the visual image to solve this inverse problem; however, the nature of the comparisons and the mechanisms underlying them are topics of intense debate. Perceptual illusions are of value because they reveal important information about these visual processing mechanisms. We propose a framework for lightness research that resolves confusions and paradoxes in the literature, and provides insight into the mechanisms the visual system employs to tackle the inverse problem. The main idea is that much of the debate and confusion in the literature stems from the fact that lightness, defined as apparent reflectance, is underspecified and refers to three different types of judgments that are not comparable. Under stimulus conditions containing a visible illumination component, such as a shadow boundary, observers can distinguish and match three independent dimensions of achromatic experience: apparent intensity (brightness), apparent local intensity ratio (brightness-contrast), and apparent reflectance (lightness). In the absence of a visible illumination boundary, however, achromatic vision reduces to two dimensions and, depending on stimulus conditions and observer instructions, judgments of lightness are identical to judgments of brightness or brightness-contrast. Furthermore, because lightness judgments are based on different information under different conditions, they can differ greatly in their degree of difficulty and in their accuracy. This may, in part, explain the large variability in lightness constancy across studies. PMID:25954181

  10. Reconfigurable, Bi-Directional Flexfet Level Shifter for Low-Power, Rad-Hard Integration

    NASA Technical Reports Server (NTRS)

    DeGregorio, Kelly; Wilson, Dale G.

    2009-01-01

    Two prototype Reconfigurable, Bi-directional Flexfet Level Shifters (ReBiLS) have been developed, where one version is a stand-alone component designed to interface between external low voltage and high voltage, and the other version is an embedded integrated circuit (IC) for interface between internal low-voltage logic and external high-voltage components. Targeting stand-alone and embedded circuits separately allows optimization for these distinct applications. Both ReBiLS designs use the commercially available 180-nm Flex fet Independently Double-Gated (IDG) SOI CMOS (silicon on insulator, complementary metal oxide semiconductor) technology. Embedded ReBiLS circuits were integrated with a Reed-Solomon (RS) encoder using CMOS Ultra-Low-Power Radiation Tolerant (CULPRiT) double-gated digital logic circuits. The scope of the project includes: creation of a new high-voltage process, development of ReBiLS circuit designs, and adjustment of the designs to maximize performance through simulation, layout, and manufacture of prototypes. The primary technical objectives were to develop a high-voltage, thick oxide option for the 180-nm Flexfet process, and to develop a stand-alone ReBiLS IC with two 8-channel I/O busses, 1.8 2.5 I/O on the low-voltage pins, 5.0-V-tolerant input and 3.3-V output I/O on the high-voltage pins, and 100-MHz minimum operation with 10-pF external loads. Another objective was to develop an embedded, rad-hard ReBiLS I/O cell with 0.5-V low-voltage operation for interface with core logic, 5.0-V-tolerant input and 3.3-V output I/O pins, and 100-MHz minimum operation with 10- pF external loads. A third objective was to develop a 0.5- V Reed-Solomon Encoder with embedded ReBilS I/O: Transfer the existing CULPRiT RS encoder from a 0.35-micron bulk-CMOS process to the ASI 180-nm Flexfet, rad-hard SOI Process. 0.5-V low-voltage core logic. 5.0-V-tolerant input and 3.3-V output I/O pins. 100-MHz minimum operation with 10- pF external loads. The stand

  11. Phased-array design for MST and ST radars

    NASA Technical Reports Server (NTRS)

    Ecklund, W. L.

    1986-01-01

    All of the existing radar systems fully dedicated to clear-air radar studies use some type of phased-array antennas. The effects of beam-steering techniques including feed networks and phase shifters; sidelobe control; ground-clutter suppression; low altitude coverage; arrays with integrated radiating elements and feed networks; analysis of coaxial-collinear antennas; use of arrays with multiple beams; and array testing and measure on structural design of the antenna are discussed.

  12. A 32-GHz phased array transmit feed for spacecraft telecommunications

    NASA Technical Reports Server (NTRS)

    Lee, K. A.; Rascoe, D. L.; Crist, R. A.; Huang, J.; Wamhof, P. D.; Lansing, F. S.

    1992-01-01

    A 21-element phased array transmit feed was demonstrated as part of an effort to develop and evaluate state-of-the-art transmitter and receiver components at 32 and 34 GHz for future deep-space missions. Antenna pattern measurements demonstrating electronic beam steering of the two-dimensional array are reported and compared with predictions based on measured performance of MMIC-based phase shifter and amplifier modules and Vivaldi slotline radiating elements.

  13. Design considerations for high-power VHF radar transceivers: The Poker Flat MST radar phase control system

    NASA Technical Reports Server (NTRS)

    Ecklund, W. L.; Johnson, P. E.

    1983-01-01

    Sixty-four separate 50-kW peak-power transmitters are distributed throughout the 200 x 200 meter Poker Flat MST radar antenna array. The relative phase of each transmitter is automatically controlled by a 64-channel unit located in the main building at the edge of the antenna. The phase control unit is described. In operation the RF pulse from a transmitter coupler is power divided and compared with the phase reference in a mixer. The mixer output is low-pass filtered and sampled near the center of the resulting video pulse by an amplifying sample-and-hold integrated circuit. Phase control is effected by maintaining the mixer output pulse near zero volts by amplifying the sample-and-hold output which then drives the voltage-controlled phase shifter in the direction to null the mixer output. The voltage-controlled shifter achieves over 360 deg phase shift in the range from 0.7 to 24 volts. When the voltage into the shifter tracks to either voltage limit the wrap-around control resets the voltage so that the shifter is always operating within its control range.

  14. Frequency translation of light waves by propagation around an optical ring circuit containing a frequency shifter: I. Experiment.

    PubMed

    Shimizu, K; Horiguchi, T; Koyamada, Y

    1993-11-20

    A technique for the external frequency translation of light waves is reported. The technique permits the stepwise sweeping of an optical frequency over a wide range with high linearity with respect to time. The frequency translator is composed of an optical pulse modulator and an optical ring circuit containing an acousto-optic frequency shifter and an optical amplifier. The pulse launched into the ring circuit undergoes a constant frequency shift for each circulation around the circuit and the frequency can be translated to a considerable degree from that of the original input pulse. We report a stepwise frequency translation over approximately 68 GHz for a 1.5-µm light wave with a strictly constant frequency-sweep rate and an approximately constant intensity.

  15. MEMS, Ka-Band Single-Pole Double-Throw (SPDT) Switch for Switched Line Phase Shifters

    NASA Technical Reports Server (NTRS)

    Scardelletti, Maximilian C.; Ponchak, George E.; Varaljay, Nicholas C.

    2002-01-01

    Ka-band MEMS doubly anchored cantilever beam capacitive shunt devices are used to demonstrate a MEMS SPDT switch fabricated on high resistivity silicon (HRS) utilizing finite ground coplanar waveguide (FGC) transmission lines. The SPDT switch has an insertion loss (IL), return loss (RL), and isolation of 0.3dB, 40dB, and 30 dB, respectively at Ka-band.

  16. Development of high-transmittance phase-shifting mask for ArF immersion lithography

    NASA Astrophysics Data System (ADS)

    Ahn, Won-suk; Seo, Hwan-Seok; Bang, Ju-Mi; Kim, Ji-Young; Song, Jae-Min; Seung, Byoung-Hoon; Kim, Hee-Bom; Jeon, Chan-Uk

    2015-07-01

    A new PSM using high transmittance is developed to overcome patterning process limits in ArF immersion lithography. We optimized mask structure, materials, and film thicknesses for patterning process. A new material for phase-shifter is applied to the HT-PSM to exhibit higher transmittance in ArF wavelengths and the thickness of the new material is thinner than that of the conventional 6% phase-shifter (MoSiON). A new blank structure using a MoSi shading layer with double Cr hardmasks (HM) is developed and suggested for the HTPSM process. Double HM blank stacks enable the HT-PSM to adopt thin PR process for resolution enhancement in mask process. The first Cr on the MoSi is utilized as a HM to etch MoSi shading layer, an adhesion layer for PR process, and also a capping layer to protect blind area during MoSi and phase-shifter etching. In contrast, the role of the second Cr between MoSi and phase-shifter is an etch stopper for MoSi and a HM to etch phase-shifter at the same time. However, Double HM process has some problems, such as first Cr removal during second Cr etching and complex process steps. To solve the Cr removal issues, we evaluated various Cr layers which have different etchrates and compositions. According to the evaluations, we optimized thicknesses and compositions of the two Cr layers and corresponding etching conditions. Lithography simulations demonstrate that the new HT-PSM has advantages in NILS in aerial images. As a result, initial wafer exposure experiments using the HT-PSM show 13-32% improvements in LCDU compared to that of the conventional 6% PSM due to its higher NILS.

  17. A 220 GHz reflection-type phased array concept study

    NASA Astrophysics Data System (ADS)

    Hedden, Abigail S.; Dietlein, Charles R.; Wikner, David A.

    2011-05-01

    The goal of this project is to enable light-weight, durable, and portable systems capable of performing standoff detection of person-borne improvised explosive devices (PB-IEDs) through the development of millimeter-wave reflection-type phased arrays. Electronic beam steering eliminates the need for complex mechanical scanners that are commonly implemented with millimeter-wave imaging systems and would reduce overall system size and weight. We present a concept study of a 220 GHz reflection-type phased array for the purpose of performing beam scanning of a confocal reflector system. Requirements for effective imaging of the desired target region are established, including spatial resolution, total scan angle, and number of image pixels achievable. We examine the effects of array architecture on beam characteristics as it is scanned off broadside, including Gaussicity and encircled energy. Benchmark requirements are determined and compared with the capabilities of several potential phase shifter technologies, including MEMS-based variable capacitor phase shifters, switches, and varactor diode-based phase shifters.

  18. Phase stable RF transport system

    DOEpatents

    Curtin, Michael T.; Natter, Eckard F.; Denney, Peter M.

    1992-01-01

    An RF transport system delivers a phase-stable RF signal to a load, such as an RF cavity of a charged particle accelerator. A circuit generates a calibration signal at an odd multiple frequency of the RF signal where the calibration signal is superimposed with the RF signal on a common cable that connects the RF signal with the load. Signal isolating diplexers are located at both the RF signal source end and load end of the common cable to enable the calibration to be inserted and extracted from the cable signals without any affect on the RF signal. Any phase shift in the calibration signal during traverse of the common cable is then functionally related to the phase shift in the RF signal. The calibration phase shift is used to control a phase shifter for the RF signal to maintain a stable RF signal at the load.

  19. Airborne Electronically Steerable Phased Array (AESPA) program

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The basic concept and design of a flatplate-fed transmission array are described and system performance requirements are summarized. Particular emphasis is given to the design of the aperture, the radiating element, the phase shifter, the flatplate feed, and the mechanical support structure. Fabrication and testing techniques are considered. Of the three major parameters of interest in demonstrating the performance capabilities of the transmissive array, beamwidth was shown to be the least sensitive to system amplitude and phase errors. Beam pointing angle was also shown to be relatively insensitive to errors. Close agreement between measured and calculated values was found for array gain. The greatest difference was found for array sidelone level.

  20. Monte Carlo code G3sim for simulation of plastic scintillator detectors with wavelength shifter fiber readout

    NASA Astrophysics Data System (ADS)

    Mohanty, P. K.; Dugad, S. R.; Gupta, S. K.

    2012-04-01

    A detailed description of a compact Monte Carlo simulation code "G3sim" for studying the performance of a plastic scintillator detector with wavelength shifter (WLS) fiber readout is presented. G3sim was developed for optimizing the design of new scintillator detectors used in the GRAPES-3 extensive air shower experiment. Propagation of the blue photons produced by the passage of relativistic charged particles in the scintillator is treated by incorporating the absorption, total internal, and diffuse reflections. Capture of blue photons by the WLS fibers and subsequent re-emission of longer wavelength green photons is appropriately treated. The trapping and propagation of green photons inside the WLS fiber is treated using the laws of optics for meridional and skew rays. Propagation time of each photon is taken into account for the generation of the electrical signal at the photomultiplier. A comparison of the results from G3sim with the performance of a prototype scintillator detector showed an excellent agreement between the simulated and measured properties. The simulation results can be parametrized in terms of exponential functions providing a deeper insight into the functioning of these versatile detectors. G3sim can be used to aid the design and optimize the performance of scintillator detectors prior to actual fabrication that may result in a considerable saving of time, labor, and money spent.

  1. Thick polymer-stabilized liquid crystal films for microwave phase control

    NASA Astrophysics Data System (ADS)

    Fujikake, Hideo; Kuki, Takao; Nomoto, Toshihiro; Tsuchiya, Yuzuru; Utsumi, Yozo

    2001-05-01

    This article describes the use of thick polymer-stabilized liquid crystal films in a new design for microwave variable phase shifters. A fine μm-order sized polymer network was formed in a 100-μm-thick liquid crystal film, using a photopolymerization-induced phase-separation method to stabilize the molecular alignment of the liquid crystal. Measurement of the electro-optic properties of the liquid crystal film revealed that the relaxation response time of the liquid crystal alignment was drastically decreased by doping the polymer at a concentration of several wt %. A new variable phase shifter composed of a microstrip transmission line (length: 193 mm, width: 200 μm) was also fabricated by using the liquid crystal film as the dielectric material. This device exhibited a microwave phase shift of -80° at a frequency of 20 GHz, when a drive voltage of 70Vrms was applied vertically to the liquid crystal film.

  2. Reconfigurable Wave Velocity Transmission Lines for Phased Arrays

    NASA Technical Reports Server (NTRS)

    Host, Nick; Chen, Chi-Chih; Volakis, John L.; Miranda, Felix

    2013-01-01

    Phased array antennas showcase many advantages over mechanically steered systems. However, they are also more complex, heavy and most importantly costly. This presentation paper presents a concept which overcomes these detrimental attributes by eliminating all of the phase array backend (including phase shifters). Instead, a wave velocity reconfigurable transmission line is used in a series fed array arrangement to allow phase shifting with one small (100mil) mechanical motion. Different configurations of the reconfigurable wave velocity transmission line are discussed and simulated and experimental results are presented.

  3. Manufacturing of ArF chromeless hard shifter for 65-nm technology

    NASA Astrophysics Data System (ADS)

    Park, Keun-Taek; Dieu, Laurent; Hughes, Greg P.; Green, Kent G.; Croffie, Ebo H.; Taravade, Kunal N.

    2003-12-01

    For logic design, Chrome-less Phase Shift Mask is one of the possible solutions for defining small geometry with low MEF (mask enhancement factor) for the 65nm node. There have been lots of dedicated studies on the PCO (Phase Chrome Off-axis) mask technology and several design approaches have been proposed including grating background, chrome patches (or chrome shield) for applying PCO on line/space and contact pattern. In this paper, we studied the feasibility of grating design for line and contact pattern. The design of the grating pattern was provided from the EM simulation software (TEMPEST) and the aerial image simulation software. AIMS measurements with high NA annular illumination were done. Resist images were taken on designed pattern in different focus. Simulations, AIMS are compared to verify the consistency of the process with wafer printed performance.

  4. Optical and X-Ray Observations of GRB 060526: A Complex Afterglow Consistent with an Achromatic Jet Break

    NASA Technical Reports Server (NTRS)

    Dai, X.; Halpern, J. P.; Morgan, N. D.; Armstrong, E.; Mirabal, N.; Haislip. J. B.; Reichart, D. E.; Stanek, K. Z.

    2007-01-01

    We obtained 98 R-band and 18 B, r', i' images of the optical afterglow of GRB 060526 (z = 3.21) with the MDM 1.3 m, 2.4 m, and the PROMPT telescopes at CTIO over the five nights following the burst trigger. Combining these data with other optical observations reported in GCN and the Swift XRT observations, we compare the optical and X-ray afterglow light curves of GRB 060526. Both the optical and X-ray afterglow light curves show rich features, such as flares and breaks. The densely sampled optical observations provide very good coverage at T > 10(exp 4) s. We observed a break at 2.4 x 10(exp 5) sin the optical afterglow light curve. Compared with the X-ray afterglow light curve, the break is consistent with an achromatic break supporting the beaming models of GRBs. However, the prebreak and postbreak temporal decay slopes are difficult to explain in simple afterglow models. We estimated a jet angle of theta(sub j) approx. 7deg and a prompt emission size of R(sub prompt) approx. 2 x 10(exp 14) cm. In addition, we detected several optical flares with amplitudes of (Delta)m approx. 0.2,0.6, and 0.2 mag. The X-ray afterglows detected by Swift have shown complicated decay patterns. Recently, many well-sampled optical afterglows also show decays with flares and multiple breaks. GRB 060526 provides an additional case of such a complex, well-observed optical afterglow. The accumulated well-sampled afterglows indicate that most of the optical afterglows are complex.

  5. Experimental study of the phase-shift miscalibration error in phase-shifting interferometry: use of a spectrally resolved white-light interferometer.

    PubMed

    Debnath, Sanjit K; Kothiyal, Mahendra P

    2007-08-01

    The white-light interferogram in a spectrally resolved white-light interferometer is decomposed in its constituent spectral components by a spectrometer and displayed along its chromaticity axis. A piezoelectric transducer phase shifter in such an interferometer can give a desired phase shift of pi/2 only at one wavelength. The phase shift varies continuously at all other wavelengths along the chromaticity axis. This situation is ideal for an experimental study of the phase error due to the phase-shift error in the phase-shifting technique, as it will be shown in this paper.

  6. Development of achromatic full-field hard x-ray microscopy and its application to x-ray absorption near edge structure spectromicroscopy

    NASA Astrophysics Data System (ADS)

    Matsuyama, S.; Emi, Y.; Kino, H.; Kohmura, Y.; Yabashi, M.; Ishikawa, T.; Yamauchi, K.

    2014-09-01

    An achromatic and high-resolution hard X-ray microscope was developed, in which advanced Kirkpatrick-Baez mirror optics with four total-reflection mirrors was employed as an objective. A fine test pattern with a 100 nm feature size could successfully be resolved. Full-field imaging, in combination with X-ray absorption near edge structure (XANES) spectroscopy, was used to characterize tungsten particles. XANES spectra were obtained over the entire observation area, showing good agreement with the XANES spectrum of pure tungsten.

  7. Noise performance of a feed-forward scheme for carrier-envelope phase stabilization

    NASA Astrophysics Data System (ADS)

    Koke, S.; Anderson, A.; Frei, H.; Assion, A.; Steinmeyer, G.

    2011-09-01

    The noise performance of a feed-forward scheme for carrier-envelope phase stabilization is discussed. This scheme uses an acousto-optic frequency shifter to directly correct for fluctuations of the carrier-envelope phase in a pulse train emitted by a mode-locked laser without manipulating the intracavity dispersion. Generation of zero-offset frequency combs is demonstrated. Furthermore, it is shown that pump laser noise has only a minor effect on the achievable performance. Limited only by the travel time of the acoustic wave in the shifter, pump laser noise can be corrected up to near-megahertz frequencies, which yields superior noise performance compared to traditional feedback operation. Residual phase jitters down to 45 mrad are experimentally verified.

  8. Digital Phase Meter for a Laser Heterodyne Interferometer

    NASA Technical Reports Server (NTRS)

    Loya, Frank

    2008-01-01

    The Digital Phase Meter is based on a modified phase-locked loop. When phase alignment between the reference input and the phase-shifted metrological input is achieved, the loop locks and the phase shift of the digital phase shifter equals the phase difference that one seeks to measure. This digital phase meter is being developed for incorporation into a laser heterodyne interferometer in a metrological apparatus, but could also be adapted to other uses. Relative to prior phase meters of similar capability, including digital ones, this digital phase meter is smaller, less complex, and less expensive. The phase meter has been constructed and tested in the form of a field-programmable gate array (FPGA).

  9. Focal plane wavefront sensor achromatization: The multireference self-coherent camera

    NASA Astrophysics Data System (ADS)

    Delorme, J. R.; Galicher, R.; Baudoz, P.; Rousset, G.; Mazoyer, J.; Dupuis, O.

    2016-04-01

    Context. High contrast imaging and spectroscopy provide unique constraints for exoplanet formation models as well as for planetary atmosphere models. But this can be challenging because of the planet-to-star small angular separation (<1 arcsec) and high flux ratio (>105). Recently, optimized instruments like VLT/SPHERE and Gemini/GPI were installed on 8m-class telescopes. These will probe young gazeous exoplanets at large separations (≳1 au) but, because of uncalibrated phase and amplitude aberrations that induce speckles in the coronagraphic images, they are not able to detect older and fainter planets. Aims: There are always aberrations that are slowly evolving in time. They create quasi-static speckles that cannot be calibrated a posteriori with sufficient accuracy. An active correction of these speckles is thus needed to reach very high contrast levels (>106-107). This requires a focal plane wavefront sensor. Our team proposed a self coherent camera, the performance of which was demonstrated in the laboratory. As for all focal plane wavefront sensors, these are sensitive to chromatism and we propose an upgrade that mitigates the chromatism effects. Methods: First, we recall the principle of the self-coherent camera and we explain its limitations in polychromatic light. Then, we present and numerically study two upgrades to mitigate chromatism effects: the optical path difference method and the multireference self-coherent camera. Finally, we present laboratory tests of the latter solution. Results: We demonstrate in the laboratory that the multireference self-coherent camera can be used as a focal plane wavefront sensor in polychromatic light using an 80 nm bandwidth at 640 nm (bandwidth of 12.5%). We reach a performance that is close to the chromatic limitations of our bench: 1σ contrast of 4.5 × 10-8 between 5 and 17 λ0/D. Conclusions: The performance of the MRSCC is promising for future high-contrast imaging instruments that aim to actively minimize the

  10. SAR processing with stepped chirps and phased array antennas.

    SciTech Connect

    Doerry, Armin Walter

    2006-09-01

    Wideband radar signals are problematic for phased array antennas. Wideband radar signals can be generated from series or groups of narrow-band signals centered at different frequencies. An equivalent wideband LFM chirp can be assembled from lesser-bandwidth chirp segments in the data processing. The chirp segments can be transmitted as separate narrow-band pulses, each with their own steering phase operation. This overcomes the problematic dilemma of steering wideband chirps with phase shifters alone, that is, without true time-delay elements.

  11. Self-Referenced Scheme for Direct Synthesis of Carrier-Envelope Phase Stable Pulses with Jitter below the Atomic Time Unit

    NASA Astrophysics Data System (ADS)

    Steinmeyer, Günter; Grebing, Christian; Borchers, Bastian; Koke, Sebastian

    A method for stabilizing the carrier-envelope phase of mode-locked oscillators is introduced. Other than previous concepts that exerted feedback action directly on the oscillator, our novel feed-forward concept employs an acousto-optic frequency shifter after the oscillator to correct the phase drift. This novel method is shown to simultaneously provide superior residual phase jitters and long-term performance, enabling previously considered impossible experiments in attosecond physics.

  12. Reconfigurable Transmission Line for a Series-Fed Ku-Band Phased Array Using a Single Feed

    NASA Technical Reports Server (NTRS)

    Host, Nicholas K.; Chen, Chi-Chih; Volakis, John L.; Miranda. Felix, A.

    2013-01-01

    The paper presents a novel approach to realize a lowcost phased array using a simple feeding mechanism. Specifically, a single coplanar stripline (CPS) transmission line is used to feed the antenna array elements. By controlling the CPS's dielectric properties using a movable dielectric plunger, scanning is achieved. Due to its simplicity, single feed, and no phase shifters, this approach leads to a dramatic reduction in cost which does not scale for larger arrays.

  13. Ka-Band Phased Array System Characterization

    NASA Technical Reports Server (NTRS)

    Acosta, R.; Johnson, S.; Sands, O.; Lambert, K.

    2001-01-01

    Phased Array Antennas (PAAs) using patch-radiating elements are projected to transmit data at rates several orders of magnitude higher than currently offered with reflector-based systems. However, there are a number of potential sources of degradation in the Bit Error Rate (BER) performance of the communications link that are unique to PAA-based links. Short spacing of radiating elements can induce mutual coupling between radiating elements, long spacing can induce grating lobes, modulo 2 pi phase errors can add to Inter Symbol Interference (ISI), phase shifters and power divider network introduce losses into the system. This paper describes efforts underway to test and evaluate the effects of the performance degrading features of phased-array antennas when used in a high data rate modulation link. The tests and evaluations described here uncover the interaction between the electrical characteristics of a PAA and the BER performance of a communication link.

  14. Nonlinearities in digital manifold phased arrays

    NASA Astrophysics Data System (ADS)

    Mathews, Bruce D.

    1986-11-01

    In digital beamforming (DBF), the phase shifter is functionally replaced with a receiver and digital phase rotation. A Taylor series expansion of mixer nonlinearities is used to generate receiver intermodulation spectrums respective of the element position and the iso-Doppler wavefront directions of signal arrival across the array. The dominant intermodulation distortion at each element experiences linear phase errors across the array proportional to the harmonic number and the desired steering direction phase gradient. The array distortion signals are reduced relative to the desired signal by the array factor sidelobe isolation when desired collimation directions exceed a few beamwidths of scan off the array normal vector. The result of the nonlinear down conversion analysis is extended to inphase and quadrature imbalances and batch manufacturing tolerances for element receivers.

  15. A design concept for an MMIC (Monolithic Microwave Integrated Circuit) microstrip phased array

    NASA Technical Reports Server (NTRS)

    Lee, Richard Q.; Smetana, Jerry; Acosta, Roberto

    1987-01-01

    A conceptual design for a microstrip phased array with monolithic microwave integrated circuit (MMIC) amplitude and phase controls is described. The MMIC devices used are 20 GHz variable power amplifiers and variable phase shifters recently developed by NASA contractors for applications in future Ka proposed design, which concept is for a general NxN element array of rectangular lattice geometry. Subarray excitation is incorporated in the MMIC phased array design to reduce the complexity of the beam forming network and the number of MMIC components required.

  16. An optically controlled phased array antenna based on single sideband polarization modulation.

    PubMed

    Zhang, Yamei; Wu, Huan; Zhu, Dan; Pan, Shilong

    2014-02-24

    A novel optically controlled phased array antenna consisting a simple optical beamforming network and an N element linear patch antenna array is proposed and demonstrated. The optical beamforming network is realized by N independent phase shifters using a shared optical single sideband (OSSB) polarization modulator together with N polarization controllers (PCs), N polarization beam splitters (PBSs) and N photodetectors (PDs). An experiment is carried out. A 4-element linear patch antenna array operating at 14 GHz and a 1 × 4 optical beamforming network (OBFN) is employed to realize the phased array antenna. The radiation patterns of the phased array antenna at -30°, 0° and 30° are achieved.

  17. Luminescent and scintillating properties of lanthanum fluoride nanocrystals in response to gamma/neutron irradiation: codoping with Ce activator, Yb wavelength shifter, and Gd neutron captor

    NASA Astrophysics Data System (ADS)

    Vargas, J. M.; Blostein, J. J.; Sidelnik, I.; Rondón Brito, D.; Rodríguez Palomino, L. A.; Mayer, R. E.

    2016-09-01

    A novel concept for gamma radiation detection and spectroscopy, and detection of thermal neutrons based on co-doped lanthanum fluoride nanocrystals containing gadolinium is presented. The trends of colloidal synthesis of the mentioned material, LaF3 co-doped with Ce3+ as the activator, Yb3+ as the wavelength-shifter and Gd3+ as the neutron captor, is reported. Nanocrystals of the mentioned material were characterized by transmission electron microscopy, X ray diffraction, energy dispersive X ray spectroscopy, optical absorption, and photoluminescence spectroscopy. Gamma detection and its potential spectroscopy feature have been confirmed. The neutron detection capability has been confirmed by experiments performed using a 252Cf neutron source.

  18. X-band printed phased array antennas using high-performance CNT/ion gel/Ag transistors

    NASA Astrophysics Data System (ADS)

    Grubb, Peter M.; Bidoky, Fazel; Mahajan, Ankit; Subbaraman, Harish; Li, Wentao; Frisbie, Daniel; Chen, Ray T.

    2016-05-01

    This paper reports a fully printed phased array antenna developed on a 125 micron thick flexible Kapton substrate. Switching for the phase delay lines is accomplished using printed carbon nanotube transistors with ion gel dielectric layers. Design of each element of the phased array antenna is reported, including a low loss constant impedance power divider, a phase shifter network, and patch antenna design. Steering of an X-band PAA operating at 10GHz from 0 degrees to 22.15 degrees is experimentally demonstrated. In order to completely package the array with electrical interconnects, a single substrate interconnect scheme is also investigated.

  19. Frequency/phase agile microwave circuits on ferroelectric films

    NASA Astrophysics Data System (ADS)

    Romanofsky, Robert Raymond

    This work describes novel microwave circuits that can be tuned in either frequency or phase through the use of nonlinear dielectrics, specifically thin ferroelectric films. These frequency and phase agile circuits in many cases provide a new capability or offer the potential for lower cost alternatives in satellite and terrestrial communications and sensor applications. A brief introduction to nonlinear dielectrics and a summary of some of the special challenges confronting the practical insertion of ferroelectric technology into commercial systems is provided. A theoretical solution for the propagation characteristics of the multi-layer structures, with emphasis on a new type of phase shifter based on coupled microstrip, lines, is developed. The quasi-TEM analysis is based on a variational solution for line capacitance and an extension of coupled transmission line theory. It is shown that the theoretical model is applicable to a broad class of multi-layer transmission lines. The critical role that ferroelectric film thickness plays in loss and phase-shift is closely examined. Experimental data for both thin film BaxSr1-xTiO 3 phase shifters near room temperature and SMO3 phase shifters at cryogenic temperatures on MgO and LaAlO3 substrates is included. Some of these devices demonstrated an insertion loss of less than 5 dB at Ku-band with continuously variable phase shift in excess of 360 degrees. The performance of these devices is superior to the state-of-the-art semiconductor counterparts. Frequency and phase agile antenna prototypes including a microstrip patch that can operate at multiple microwave frequency bands and a new type of phased array antenna concept called the ferroelectric reflectarray are introduced. Modeled data for tunable microstrip patch antennas is presented for various ferroelectric film thickness. A prototype linear phased array, with a conventional beam-forming manifold, and an electronic controller is described. This is the first

  20. A Hybrid Reflective/Refractive/Diffractive Achromatic Fiber-Coupled Radiation Resistant Imaging System for Use in the Spallation Neutron Source (SNS)

    SciTech Connect

    Maxey, L Curt; Ally, Tanya R; Brunson, Aly; Garcia, Frances; Goetz, Kathleen C; Hasse, Katelyn E; McManamy, Thomas J; Shea, Thomas J; Simpson, Marc Livingstone

    2011-01-01

    A fiber-coupled imaging system for monitoring the proton beam profile on the target of the Spallation Neutron Source was developed using reflective, refractive and diffractive optics to focus an image onto a fiber optic imaging bundle. The imaging system monitors the light output from a chromium-doped aluminum oxide (Al{sub 2}0{sub 3}:Cr) scintillator on the nose of the target. Metal optics are used to relay the image to the lenses that focus the image onto the fiber. The material choices for the lenses and fiber were limited to high-purity fused silica, due to the anticipated radiation dose of 10{sup 8} R. In the first generation system (which had no diffractive elements), radiation damage to the scintillator on the nose of the target significantly broadened the normally monochromatic (694 nm) spectrum. This created the need for an achromatic design in the second generation system. This was achieved through the addition of a diffractive optic for chromatic correction. An overview of the target imaging system and its performance, with particular emphasis on the design and testing of a hybrid refractive/diffractive high-purity fused silica imaging triplet, is presented.

  1. The effect of the color red on consuming food does not depend on achromatic (Michelson) contrast and extends to rubbing cream on the skin.

    PubMed

    Bruno, Nicola; Martani, Margherita; Corsini, Claudia; Oleari, Claudio

    2013-12-01

    Recent literature suggests that individuals may consume less food when this is served on red plates. We explored this intriguing effect in three experiments. Independent groups of participants were presented with constant amounts of popcorns, chocolate chips, or moisturizing cream, on red, blue, or white plates. They were asked to sample the foods (by tasting them) or the cream (by rubbing it on the hand and forearm) as they wished and to complete mock "sensory analysis" questionnaires. Results confirmed that red plates reduce taste-related consumption and extended this effect to the touch-related consumption of moisturizing cream. Suggesting that the effect was not due to a decrease in the consciously experienced appeal of products on red plates, overall appreciation of the foods or cream did not differ according to plate color. After careful photometric measures of the materials used for each food-plate pairing, we determined that food and cream consumption was not predicted by Michelson (achromatic) contrast. Although the origin of the intriguing effect of the color red on consumption remains unclear, our results may prove useful to future potential explanations. PMID:23999521

  2. Temperature dependence of alpha-induced scintillation in the 1,1,4,4-tetraphenyl-1,3-butadiene wavelength shifter

    NASA Astrophysics Data System (ADS)

    Veloce, L. M.; Kuźniak, M.; Di Stefano, P. C. F.; Noble, A. J.; Boulay, M. G.; Nadeau, P.; Pollmann, T.; Clark, M.; Piquemal, M.; Schreiner, K.

    2016-06-01

    Liquid noble based particle detectors often use the organic wavelength shifter 1,1,4,4-tetraphenyl-1,3-butadiene (TPB) which shifts UV scintillation light to the visible regime, facilitating its detection, but which also can scintillate on its own. Dark matter searches based on this type of detector commonly rely on pulse-shape discrimination (PSD) for background mitigation. Alpha-induced scintillation therefore represents a possible background source in dark matter searches. The timing characteristics of this scintillation determine whether this background can be mitigated through PSD. We have therefore characterized the pulse shape and light yield of alpha induced TPB scintillation at temperatures ranging from 300 K down to 4 K, with special attention given to liquid noble gas temperatures. We find that the pulse shapes and light yield depend strongly on temperature. In addition, the significant contribution of long time constants above ~50 K provides an avenue for discrimination between alpha decay events in TPB and nuclear-recoil events in noble liquid detectors.

  3. Achromatic digital speckle pattern interferometer with constant radial in-plane sensitivity by using a diffractive optical element.

    PubMed

    Viotti, Matias R; Kapp, Walter; Albertazzi G, Armando

    2009-04-20

    We report on a digital speckle pattern interferometer that applies a binary diffractive optical element (DOE) to generate double illumination and radial in-plane sensitivity. The application of the DOE ensures independence on the wavelength of the laser used as an illumination source. Furthermore, in-plane sensitivity only depends on the grating period of the DOE. An experimental setup was built allowing the measurement of a set of radial in-plane displacement fields either using a red laser as a light source or a green one. When displacement fields computed from the measured optical phase maps obtained with a red or a green laser were compared, two main results were observed: (a) deviations between mean values ranged only up to 7 nm and (b) phase maps presented the same amount of fringes. In addition, phase maps measured with the red laser were processed as they were obtained with green light. For this case, deviations have ranged only up to 0.5 nm. On the other hand, a set of measurements performed changing the DOE by a conical mirror showed clearly that radial in-plane sensitivity increased when the red laser was changed by the green one. PMID:19381178

  4. Phased Array Radiometer Calibration Using a Radiated Noise Source

    NASA Technical Reports Server (NTRS)

    Srinivasan, Karthik; Limaye, Ashutoch S.; Laymon, Charles A.; Meyer, Paul J.

    2010-01-01

    Electronic beam steering capability of phased array antenna systems offer significant advantages when used in real aperture imaging radiometers. The sensitivity of such systems is limited by the ability to accurately calibrate variations in the antenna circuit characteristics. Passive antenna systems, which require mechanical rotation to scan the beam, have stable characteristics and the noise figure of the antenna can be characterized with knowledge of its physical temperature [1],[2]. Phased array antenna systems provide the ability to electronically steer the beam in any desired direction. Such antennas make use of active components (amplifiers, phase shifters) to provide electronic scanning capability while maintaining a low antenna noise figure. The gain fluctuations in the active components can be significant, resulting in substantial calibration difficulties [3]. In this paper, we introduce two novel calibration techniques that provide an end-to-end calibration of a real-aperture, phased array radiometer system. Empirical data will be shown to illustrate the performance of both methods.

  5. A design concept for an MMIC microstrip phased array

    NASA Technical Reports Server (NTRS)

    Lee, R. Q.; Smetana, J.; Acosta, R.

    1986-01-01

    A conceptual design for a microstrip phased array with monolithic microwave integrated circuit (MMIC) amplitude and phase controls is described. The MMIC devices used are 20 GHz variable power amplifiers and variable phase shifters recently developed by NASA contractors for applications in future Ka band advanced satellite communication antenna systems. The proposed design concept is for a general NxN element array of rectangular lattice geometry. Subarray excitation is incorporated in the MMIC phased array design to reduce the complexity of the beam forming network and the number of MMIC components required. The proposed design concept takes into consideration the RF characteristics and actual phyical dimensions of the MMIC devices. Also, solutions to spatial constraints and interconnections associated with currently available packaging designs are discussed. Finally, the design of the microstrip radiating elements and their radiation characteristics are examined.

  6. Monolithic optical phased-array transceiver in a standard SOI CMOS process.

    PubMed

    Abediasl, Hooman; Hashemi, Hossein

    2015-03-01

    Monolithic microwave phased arrays are turning mainstream in automotive radars and high-speed wireless communications fulfilling Gordon Moores 1965 prophecy to this effect. Optical phased arrays enable imaging, lidar, display, sensing, and holography. Advancements in fabrication technology has led to monolithic nanophotonic phased arrays, albeit without independent phase and amplitude control ability, integration with electronic circuitry, or including receive and transmit functions. We report the first monolithic optical phased array transceiver with independent control of amplitude and phase for each element using electronic circuitry that is tightly integrated with the nanophotonic components on one substrate using a commercial foundry CMOS SOI process. The 8 × 8 phased array chip includes thermo-optical tunable phase shifters and attenuators, nano-photonic antennas, and dedicated control electronics realized using CMOS transistors. The complex chip includes over 300 distinct optical components and over 74,000 distinct electrical components achieving the highest level of integration for any electronic-photonic system.

  7. Monolithic optical phased-array transceiver in a standard SOI CMOS process.

    PubMed

    Abediasl, Hooman; Hashemi, Hossein

    2015-03-01

    Monolithic microwave phased arrays are turning mainstream in automotive radars and high-speed wireless communications fulfilling Gordon Moores 1965 prophecy to this effect. Optical phased arrays enable imaging, lidar, display, sensing, and holography. Advancements in fabrication technology has led to monolithic nanophotonic phased arrays, albeit without independent phase and amplitude control ability, integration with electronic circuitry, or including receive and transmit functions. We report the first monolithic optical phased array transceiver with independent control of amplitude and phase for each element using electronic circuitry that is tightly integrated with the nanophotonic components on one substrate using a commercial foundry CMOS SOI process. The 8 × 8 phased array chip includes thermo-optical tunable phase shifters and attenuators, nano-photonic antennas, and dedicated control electronics realized using CMOS transistors. The complex chip includes over 300 distinct optical components and over 74,000 distinct electrical components achieving the highest level of integration for any electronic-photonic system. PMID:25836869

  8. A 2x2 W-Band Reference Time-Shifted Phase-Locked Transmitter Array in 65nm CMOS Technology

    NASA Technical Reports Server (NTRS)

    Tang, Adrian; Virbila, Gabriel; Hsiao, Frank; Wu, Hao; Murphy, David; Mehdi, Imran; Siegel, P. H.; Chang, M-C. Frank

    2013-01-01

    This paper presents a complete 2x2 phased array transmitter system operating at W-band (90-95 GHz) which employs a PLL reference time-shifting approach instead of using traditional mm-wave phase shifters. PLL reference shifting enables a phased array to be distributed over multiple chips without the need for coherent mm-wave signal distribution between chips. The proposed phased array transmitter system consumes 248 mW per array element when implemented in a 65 nm CMOS technology.

  9. The selectivity of responses to red-green colour and achromatic contrast in the human visual cortex: an fMRI adaptation study.

    PubMed

    Mullen, Kathy T; Chang, Dorita H F; Hess, Robert F

    2015-12-01

    There is controversy as to how responses to colour in the human brain are organized within the visual pathways. A key issue is whether there are modular pathways that respond selectively to colour or whether there are common neural substrates for both colour and achromatic (Ach) contrast. We used functional magnetic resonance imaging (fMRI) adaptation to investigate the responses of early and extrastriate visual areas to colour and Ach contrast. High-contrast red-green (RG) and Ach sinewave rings (0.5 cycles/degree, 2 Hz) were used as both adapting stimuli and test stimuli in a block design. We found robust adaptation to RG or Ach contrast in all visual areas. Cross-adaptation between RG and Ach contrast occurred in all areas indicating the presence of integrated, colour and Ach responses. Notably, we revealed contrasting trends for the two test stimuli. For the RG test, unselective processing (robust adaptation to both RG and Ach contrast) was most evident in the early visual areas (V1 and V2), but selective responses, revealed as greater adaptation between the same stimuli than cross-adaptation between different stimuli, emerged in the ventral cortex, in V4 and VO in particular. For the Ach test, unselective responses were again most evident in early visual areas but Ach selectivity emerged in the dorsal cortex (V3a and hMT+). Our findings support a strong presence of integrated mechanisms for colour and Ach contrast across the visual hierarchy, with a progression towards selective processing in extrastriate visual areas.

  10. Integrated phased array for wide-angle beam steering.

    PubMed

    Yaacobi, Ami; Sun, Jie; Moresco, Michele; Leake, Gerald; Coolbaugh, Douglas; Watts, Michael R

    2014-08-01

    We demonstrate an on-chip optical phased array fabricated in a CMOS compatible process with continuous, fast (100 kHz), wide-angle (51°) beam-steering suitable for applications such as low-cost LIDAR systems. The device demonstrates the largest (51°) beam-steering and beam-spacing to date while providing the ability to steer continuously over the entire range. Continuous steering is enabled by a cascaded phase shifting architecture utilizing, low power and small footprint, thermo-optic phase shifters. We demonstrate these results in the telecom C-band, but the same design can easily be adjusted for any wavelength between 1.2 and 3.5 μm.

  11. Two-dimensional optical architecture for time-delay beam forming in a phased-array antenna.

    PubMed

    Dolfi, D; Michel-Gabriel, F; Bann, S; Huignard, J P

    1991-02-15

    We propose and experimentally demonstrate a new two-dimensional optical architecture based on polarization switching by N spatial light modulators that provides 2(N) time delays to a phased-array antenna of p x p radiating elements. Moreover the 0 to 2pi phase of the microwave signals is optically controlled by a liquid-crystal spatial light modulator that operates in the birefringent mode. The microwave signal originates from the coherent detection of a dual-frequency laser beam obtained with an acousto-optic frequency shifter. Preliminary experimental results obtained at a microwave frequency f = 1.85 GHz are presented.

  12. Two-dimensional optical architecture for time-delay beam forming in a phased-array antenna.

    PubMed

    Dolfi, D; Michel-Gabriel, F; Bann, S; Huignard, J P

    1991-02-15

    We propose and experimentally demonstrate a new two-dimensional optical architecture based on polarization switching by N spatial light modulators that provides 2(N) time delays to a phased-array antenna of p x p radiating elements. Moreover the 0 to 2pi phase of the microwave signals is optically controlled by a liquid-crystal spatial light modulator that operates in the birefringent mode. The microwave signal originates from the coherent detection of a dual-frequency laser beam obtained with an acousto-optic frequency shifter. Preliminary experimental results obtained at a microwave frequency f = 1.85 GHz are presented. PMID:19773900

  13. Phase noise analysis of the sapphire loaded superconducting niobium cavity oscillator

    NASA Astrophysics Data System (ADS)

    Tobar, Michael; Blair, David G.

    1994-02-01

    Measured phase noise of two GaAs FET amplifiers and a varactor phase shifter at 9.7 GHz reveal that optimum bias conditions change when cooling from room to liquid helium temperatures. This understanding enables optimization of the electronic noise in an all cryogenic tunable sapphire loaded superconducting cavity (SLOSC) X-Band loop oscillator. The measured phase noise was limited by vibrations of the tuning mechanism. In a fixed frequency SLOSC oscillator the phase noise was limited by the amplifier noise, and has been measured to be -140 dBc/Hz at 1 kHz from the unfiltered port of loop oscillator. Comparison of component and oscillator phase noise allows us to calculate the phase noise at the filtered port to be -175 dBc/ Hz at 1 kHz offset.

  14. Dual-Wavelength Terahertz Metasurfaces with Independent Phase and Amplitude Control at Each Wavelength

    NASA Astrophysics Data System (ADS)

    Ding, Jun; Xu, Ningning; Ren, Han; Lin, Yuankun; Zhang, Weili; Zhang, Hualiang

    2016-09-01

    We have designed, fabricated and characterized dual-wavelength metasurfaces that function at two assigned terahertz wavelengths with independent phase and amplitude control at each wavelength. Specifically, we have designed a dual-wavelength achromatic metasurface-based deflector deflecting the incident wave to the same direction at two selected wavelengths, which has circumvented the critical limitation of strong wavelength dependence in the planar metasurface-based devices caused by the resonant nature of the plasmonic structures. As a proof of concept demonstration, the designed dual-wavelength achromatic deflector has been fabricated, and characterized experimentally. The numerical simulations, theoretical predictions, and experimental results agree very well with each other, demonstrating the property of independently manipulating the phase profiles at two wavelengths. Furthermore, another unique feature of the designed metasurface is that it can independently tailor both the phase and amplitude profiles at two wavelengths. This property has been numerically validated by engineering a metasurface-based device to simultaneously generate two diffraction orders at two desired wavelengths.

  15. Dual-Wavelength Terahertz Metasurfaces with Independent Phase and Amplitude Control at Each Wavelength

    PubMed Central

    Ding, Jun; Xu, Ningning; Ren, Han; Lin, Yuankun; Zhang, Weili; Zhang, Hualiang

    2016-01-01

    We have designed, fabricated and characterized dual-wavelength metasurfaces that function at two assigned terahertz wavelengths with independent phase and amplitude control at each wavelength. Specifically, we have designed a dual-wavelength achromatic metasurface-based deflector deflecting the incident wave to the same direction at two selected wavelengths, which has circumvented the critical limitation of strong wavelength dependence in the planar metasurface-based devices caused by the resonant nature of the plasmonic structures. As a proof of concept demonstration, the designed dual-wavelength achromatic deflector has been fabricated, and characterized experimentally. The numerical simulations, theoretical predictions, and experimental results agree very well with each other, demonstrating the property of independently manipulating the phase profiles at two wavelengths. Furthermore, another unique feature of the designed metasurface is that it can independently tailor both the phase and amplitude profiles at two wavelengths. This property has been numerically validated by engineering a metasurface-based device to simultaneously generate two diffraction orders at two desired wavelengths. PMID:27659800

  16. Selective reduction of fMRI responses to transient achromatic stimuli in the magnocellular layers of the LGN and the superficial layer of the SC of early glaucoma patients.

    PubMed

    Zhang, Peng; Wen, Wen; Sun, Xinghuai; He, Sheng

    2016-02-01

    Glaucoma is now viewed not just a disease of the eye but also a disease of the brain. The prognosis of glaucoma critically depends on how early the disease can be detected. However, early glaucomatous loss of the laminar functions in the human lateral geniculate nucleus (LGN) and superior colliculus (SC) remains difficult to detect and poorly understood. Using functional MRI, we measured neural signals from different layers of the LGN and SC, as well as from the early visual cortices (V1, V2 and MT), in patients with early-stage glaucoma and normal controls. Compared to normal controls, early glaucoma patients showed more reduction of response to transient achromatic stimuli than to sustained chromatic stimuli in the magnocellular layers of the LGN, as well as in the superficial layer of the SC. Magnocellular responses in the LGN were also significantly correlated with the degree of behavioral deficits to the glaucomatous eye. Finally, early glaucoma patients showed no reduction of fMRI response in the early visual cortex. These findings demonstrate that 'large cells' in the human LGN and SC suffer selective loss of response to transient achromatic stimuli at the early stage of glaucoma. Hum Brain Mapp 37:558-569, 2016. © 2015 Wiley Periodicals, Inc.

  17. Microstrip Antennas with Broadband Integrated Phase Shifting

    NASA Technical Reports Server (NTRS)

    Bernhard, Jennifer T.; Romanofsky, Robert R. (Technical Monitor)

    2001-01-01

    The goal of this research was to investigate the feasibility of using a spiral microstrip antenna that incorporates a thin ferroelectric layer to achieve both radiation and phase shifting. This material is placed between the conductive spiral antenna structure and the grounded substrate. Application of a DC bias between the two arms of the spiral antenna will change the effective permittivity of the radiating structure and the degree of coupling between contiguous spiral arms, therefore changing the phase of the RF signal transmitted or received by the antenna. This could eliminate the need for a separate phase shifter apart from the antenna structure. The potential benefits of such an antenna element compared to traditional phased array elements include: continuous, broadband phase shifting at the antenna, lower overall system losses, lighter, more efficient, and more compact phased arrays, and simpler control algorithms. Professor Jennifer Bernhard, graduate student Gregory Huff, and undergraduate student Brian Huang participated in this effort from March 1, 2000 to February 28, 2001. No inventions resulted from the research undertaken in this cooperative agreement.

  18. MSAT-X electronically steered phased array antenna system

    NASA Technical Reports Server (NTRS)

    Chung, H. H.; Foy, W.; Schaffner, G.; Pagels, W.; Vayner, M.; Nelson, J.; Peng, S. Y.

    1988-01-01

    A low profile electronically steered phased array was successfully developed for the Mobile Satellite Experiment Program (MSAT-X). The newly invented cavity-backed printed crossed-slot was used as the radiating element. The choice of this element was based on its low elevation angle gain coverage and low profile. A nineteen-way radial type unequal power divider and eighteen three-bit diode phase shifters constitute the beamformer module which is used to scan the beams electronically. A complete hybrid mode pointing system was also developed. The major features of the antenna system are broad coverage, low profile, and fast acquisition and tracking performance, even under fading conditions. Excellent intersatellite isolation (better than 26 dB) was realized, which will provide good quality mobile satellite communication in the future.

  19. Low-power scan driver embedded with level shifter using depletion-mode amorphous indium-gallium-zinc-oxide thin-film transistors for high-resolution flat-panel displays

    NASA Astrophysics Data System (ADS)

    Lee, Chang-Hee; Kwon, Oh-Kyong

    2014-01-01

    A low-power scan driver embedded with a level shifter using depletion-mode amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) is proposed for high-resolution flat-panel displays (FPDs). In order to achieve low power consumption, the scan driver uses clock signals with a reduced voltage swing. Furthermore, the level shifter is implemented without using a diode-connected TFT. This scan driver is simulated at an output voltage swing of 30 V and an operating frequency (fop) of 153.6 kHz, which satisfy the driving conditions for 10-in. wide quadruple extended graphics array (WQXGA, 1600 × 2560) FPDs with a frame frequency of 60 Hz. The simulation results of the proposed scan driver demonstrate the successful operation even at a threshold voltage shift (ΔVth) of -2.0 V. The power consumption of the proposed scan driver per ten stages is 0.41 mW, which is 80.75% less than that reported in a previous work.

  20. Report for simultaneous, multiple independently steered beam study for Airborne Electronically Steerable Phased Array (AESPA) program

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Design concepts of an array for the formation of multiple, simultaneous, independently pointed beams for satellite communication links were investigated through tradeoffs of various approaches which were conceived as possible solutions to the problem. After the preferred approach was selected, a more detailed design was configured and is presented as a candidate system that should be given further consideration for development leading to a preliminary design. This array uses an attenuator and a phase shifter with every element. The aperture excitation necessary to form the four beams is calculated and then placed across the array using these devices. Pattern analysis was performed for two beam and four beam cases with numerous patterns being presented. Parameter evaluation shown includes pointing accuracy and beam shape, sidelobe characteristics, gain control, and beam normalization. It was demonstrated that a 4 bit phase shifter and a 6 bit, 30 dB attenuator were sufficient to achieve adequate pattern performances. The phase amplitude steered multibeam array offers the flexibility of 1 to 4 beams with an increase in gain of 6 dB if only one beam is selected.

  1. Achromatic self-referencing interferometer

    DOEpatents

    Feldman, M.

    1994-04-19

    A self-referencing Mach-Zehnder interferometer is described for accurately measuring laser wavefronts over a broad wavelength range (for example, 600 nm to 900 nm). The apparatus directs a reference portion of an input beam to a reference arm and a measurement portion of the input beam to a measurement arm, recombines the output beams from the reference and measurement arms, and registers the resulting interference pattern ([open quotes]first[close quotes] interferogram) at a first detector. Optionally, subportions of the measurement portion are diverted to second and third detectors, which respectively register intensity and interferogram signals which can be processed to reduce the first interferogram's sensitivity to input noise. The reference arm includes a spatial filter producing a high quality spherical beam from the reference portion, a tilted wedge plate compensating for off-axis aberrations in the spatial filter output, and mirror collimating the radiation transmitted through the tilted wedge plate. The apparatus includes a thermally and mechanically stable baseplate which supports all reference arm optics, or at least the spatial filter, tilted wedge plate, and the collimator. The tilted wedge plate is mounted adjustably with respect to the spatial filter and collimator, so that it can be maintained in an orientation in which it does not introduce significant wave front errors into the beam propagating through the reference arm. The apparatus is polarization insensitive and has an equal path length configuration enabling measurement of radiation from broadband as well as closely spaced laser line sources. 3 figures.

  2. Achromatic self-referencing interferometer

    DOEpatents

    Feldman, Mark

    1994-01-01

    A self-referencing Mach-Zehnder interferometer for accurately measuring laser wavefronts over a broad wavelength range (for example, 600 nm to 900 nm). The apparatus directs a reference portion of an input beam to a reference arm and a measurement portion of the input beam to a measurement arm, recombines the output beams from the reference and measurement arms, and registers the resulting interference pattern ("first" interferogram) at a first detector. Optionally, subportions of the measurement portion are diverted to second and third detectors, which respectively register intensity and interferogram signals which can be processed to reduce the first interferogram's sensitivity to input noise. The reference arm includes a spatial filter producing a high quality spherical beam from the reference portion, a tilted wedge plate compensating for off-axis aberrations in the spatial filter output, and mirror collimating the radiation transmitted through the tilted wedge plate. The apparatus includes a thermally and mechanically stable baseplate which supports all reference arm optics, or at least the spatial filter, tilted wedge plate, and the collimator. The tilted wedge plate is mounted adjustably with respect to the spatial filter and collimator, so that it can be maintained in an orientation in which it does not introduce significant wave front errors into the beam propagating through the reference arm. The apparatus is polarization insensitive and has an equal path length configuration enabling measurement of radiation from broadband as well as closely spaced laser line sources.

  3. An adaptive microwave phased array for targeted heating of deep tumours in intact breast: animal study results.

    PubMed

    Fenn, A J; Wolf, G L; Fogle, R M

    1999-01-01

    It has previously been reported in phantoms, that an adaptive radiofrequency phased array can generate deep focused heating distributions without overheating the skin and superficial healthy tissues. The present study involves adaptive microwave phased array hyperthermia tests in animals (rabbits) with and without tumours. The design of the adaptive phased array as applied to the treatment of tumours in intact breast, is described. The adaptive phased array concept uses breast compression and dual-opposing 915 MHz air-cooled waveguide applicators with electronic phase shifters and electric-field feedback, to focus automatically by computer control the microwave radiation in deep tissue. Temperature measurements for a clinical adaptive phased array hyperthermia system demonstrate tissue heating at depth with reduced skin heating.

  4. Free space optical communication link using a silicon photonic optical phased array

    NASA Astrophysics Data System (ADS)

    Rabinovich, William S.; Goetz, Peter G.; Pruessner, Marcel; Mahon, Rita; Ferraro, Mike S.; Park, Doe; Fleet, Erin; DePrenger, Michael J.

    2015-03-01

    Many components for free space optical communication systems have shrunken in size over the last decade. However, the steering systems have remained large and power hungry. Non-mechanical beam steering offers a path to reducing the size of these systems. Optical phased arrays can allow integrated beam steering elements. One of the most important aspects of an optical phased array technology is its scalability to a large number of elements. Silicon photonics can potentially offer this scalability using CMOS foundry techniques. In this paper a small-scale silicon photonic optical phased array is demonstrated for both the transmitter and receiver functions in a free space optical link. The device using an array of thermo-optically controlled waveguide phase shifters and demonstrates one-dimensional steering with a single control electrode. Transmission of a digitized video data stream over the link is shown.

  5. Phase contrast microscopy with full numerical aperture illumination.

    PubMed

    Maurer, Christian; Jesacher, Alexander; Bernet, Stefan; Ritsch-Marte, Monika

    2008-11-24

    A modification of the phase contrast method in microscopy is presented, which reduces inherent artifacts and improves the spatial resolution. In standard Zernike phase contrast microscopy the illumination is achieved through an annular ring aperture, and the phase filtering operation is performed by a corresponding phase ring in the back focal plane of the objective. The Zernike method increases the spatial resolution as compared to plane wave illumination, but it also produces artifacts, such as the halo- and the shade-off effect. Our modification consists in replacing the illumination ring by a set of point apertures which are randomly distributed over the whole aperture of the condenser, and in replacing the Zernike phase ring by a matched set of point-like phase shifters in the back focal plane of the objective. Experimentally this is done by illuminating the sample with light diffracted from a phase hologram displayed at a spatial light modulator (SLM). The subsequent filtering operation is then done with a second matched phase hologram displayed at another SLM in a Fourier plane of the imaging pathway. This method significantly reduces the halo- and shade-off artifacts whilst providing the full spatial resolution of the microscope. PMID:19030068

  6. Digital Interface Board to Control Phase and Amplitude of Four Channels

    NASA Technical Reports Server (NTRS)

    Smith, Amy E.; Cook, Brian M.; Khan, Abdur R.; Lux, James P.

    2011-01-01

    An increasing number of parts are designed with digital control interfaces, including phase shifters and variable attenuators. When designing an antenna array in which each antenna has independent amplitude and phase control, the number of digital control lines that must be set simultaneously can grow very large. Use of a parallel interface would require separate line drivers, more parts, and thus additional failure points. A convenient form of control where single-phase shifters or attenuators could be set or the whole set could be programmed with an update rate of 100 Hz is needed to solve this problem. A digital interface board with a field-programmable gate array (FPGA) can simultaneously control an essentially arbitrary number of digital control lines with a serial command interface requiring only three wires. A small set of short, high-level commands provides a simple programming interface for an external controller. Parity bits are used to validate the control commands. Output timing is controlled within the FPGA to allow for rapid update rates of the phase shifters and attenuators. This technology has been used to set and monitor eight 5-bit control signals via a serial UART (universal asynchronous receiver/transmitter) interface. The digital interface board controls the phase and amplitude of the signals for each element in the array. A host computer running Agilent VEE sends commands via serial UART connection to a Xilinx VirtexII FPGA. The commands are decoded, and either outputs are set or telemetry data is sent back to the host computer describing the status and the current phase and amplitude settings. This technology is an integral part of a closed-loop system in which the angle of arrival of an X-band uplink signal is detected and the appropriate phase shifts are applied to the Ka-band downlink signal to electronically steer the array back in the direction of the uplink signal. It will also be used in the non-beam-steering case to compensate for

  7. Phase modulation in horizontal metal-insulator-silicon-insulator-metal plasmonic waveguides.

    PubMed

    Zhu, Shiyang; Lo, G Q; Kwong, D L

    2013-04-01

    An extremely compact Si phase modulator is proposed and validated, which relies on effective modulation of the real part of modal index of horizontal metal-insulator-Si-insulator-metal plasmonic waveguides by a voltage applied between the metal cover and the Si core. Proof-of-concept devices are fabricated on silicon-on-insulator substrates using standard complementary metal-oxide-semiconductor technology using copper as the metal and thermal silicon dioxide as the insulator. A modulator with a 1-μm-long phase shifter inserted in an asymmetric Si Mach-Zehnder interferometer exhibits 9-dB extinction ratio under a 6-V/10-kHz voltage swing. Numerical simulations suggest that high speed and low driving voltage could be achieved by shortening the distance between the Si core and the n(+)-contact and by using a high-κ dielectric as the insulator, respectively.

  8. Code-modulated interferometric imaging system using phased arrays

    NASA Astrophysics Data System (ADS)

    Chauhan, Vikas; Greene, Kevin; Floyd, Brian

    2016-05-01

    Millimeter-wave (mm-wave) imaging provides compelling capabilities for security screening, navigation, and bio- medical applications. Traditional scanned or focal-plane mm-wave imagers are bulky and costly. In contrast, phased-array hardware developed for mass-market wireless communications and automotive radar promise to be extremely low cost. In this work, we present techniques which can allow low-cost phased-array receivers to be reconfigured or re-purposed as interferometric imagers, removing the need for custom hardware and thereby reducing cost. Since traditional phased arrays power combine incoming signals prior to digitization, orthogonal code-modulation is applied to each incoming signal using phase shifters within each front-end and two-bit codes. These code-modulated signals can then be combined and processed coherently through a shared hardware path. Once digitized, visibility functions can be recovered through squaring and code-demultiplexing operations. Pro- vided that codes are selected such that the product of two orthogonal codes is a third unique and orthogonal code, it is possible to demultiplex complex visibility functions directly. As such, the proposed system modulates incoming signals but demodulates desired correlations. In this work, we present the operation of the system, a validation of its operation using behavioral models of a traditional phased array, and a benchmarking of the code-modulated interferometer against traditional interferometer and focal-plane arrays.

  9. New advancements in focused ion beam repair of alternating phase-shift masks

    NASA Astrophysics Data System (ADS)

    Lessing, Joshua; Robinson, Tod; Brannen, Rey A.; Morrison, Troy B.; Holtermann, Theresa

    2003-08-01

    As advanced photolithography extends the ability to print feature sizes below the 100 nm technology node, various reticle enhancement techniques (RET) are being employed to improve resolution. An example of RET is the alternating phase shift mask (APSM), which currently challenges the ability of conventional repair techniques to repair even the most basic reticle defect. The phase shifting quartz bump is one defect type critical to the performance of APSM technology masks. These defects on the APSM reticle are caused by imperfections in the resist image during processing, resulting in a localized under or over etch of the quartz substrate. The integrated application of gas assisted etch (GAE), focused ion beam (FIB) reticle repair, and atomic force microscopy (AFM), provide a comprehensive solution for advanced reticle defect repair and characterization. Ion beam repair offers superior accuracy and precision for removal without significant damage to the underlying or adjacent quartz. The AFM technique provides quantitative measurement of 3D structures, including those associated with alternating phase shifters etched into quartz as well as embedded shifters. In the work presented in this paper, quartz bum defects were pre-scanned on an AFM tool and proprietary software algorithms were used to generate defect image and height map files for transfer to the FIB reticle repair tool via a network connection. The FIB tool then used these files to control selectively the ion dose during the corresponding quartz defect repair. A 193 nm APSM phase shift photomask with programmed defects in 400 nm line and space pattern was repaired using an FEI Stylus NanoProfilometer (SNP) and a FEI Accura 850 focus ion beam (FIB) tool. Using the APSM FIB repair method, the transmittance evaluated from 193 nm AIMS at the repair area was more than 90% without post-processing.

  10. A Broad-Band Phase-Contrast Wave-Front Sensor

    NASA Technical Reports Server (NTRS)

    Bloemhof, Eric; Wallace, J. Kent

    2005-01-01

    A broadband phase-contrast wave-front sensor has been proposed as a real-time wave-front sensor in an adaptive-optics system. The proposed sensor would offer an alternative to the Shack-Hartmann wave-front sensors now used in high-order adaptive-optics systems of some astronomical telescopes. Broadband sensing gives higher sensitivity than does narrow-band sensing, and it appears that for a given bandwidth, the sensitivity of the proposed phase-contrast sensor could exceed that of a Shack-Hartmann sensor. Relative to a Shack-Hartmann sensor, the proposed sensor may be optically and mechanically simpler. As described below, an important element of the principle of operation of a phase-contrast wave-front sensor is the imposition of a 90deg phase shift between diffracted and undiffracted parts of the same light beam. In the proposed sensor, this phase shift would be obtained by utilizing the intrinsic 90 phase shift between the transmitted and reflected beams in an ideal (thin, symmetric) beam splitter. This phase shift can be characterized as achromatic or broadband because it is 90deg at every wavelength over a broad wavelength range.

  11. Progress and prospects of silicon-based design for optical phased array

    NASA Astrophysics Data System (ADS)

    Hu, Weiwei; Peng, Chao; Chang-Hasnain, Connie

    2016-03-01

    The high-speed, high-efficient, compact phase modulator array is indispensable in the Optical-phased array (OPA) which has been considered as a promising technology for realizing flexible and efficient beam steering. In our research, two methods are presented to utilize high-contrast grating (HCG) as high-efficient phase modulator. One is that HCG possesses high-Q resonances that origins from the cancellation of leaky waves. As a result, sharp resonance peaks appear on the reflection spectrum thus HCGs can be utilized as efficient phase shifters. Another is that low-Q mode HCG is utilized as ultra-lightweight mirror. With MEMS technology, small HCG displacement (~50 nm) leads to large phase change (~1.7π). Effective beam steering is achieved in Connie Chang-Hasnian's group. On the other hand, we theoretically and experimentally investigate the system design for silicon-based optical phased array, including the star coupler, phased array, emission elements and far-field patterns. Further, the non-uniform optical phased array is presented.

  12. Carrier-envelope phase stabilization with sub-10 as residual timing jitter.

    PubMed

    Borchers, B; Koke, S; Husakou, A; Herrmann, J; Steinmeyer, G

    2011-11-01

    We demonstrate carrier-envelope phase (CEP) stabilization of a mode-locked Ti:sapphire oscillator with unprecedented timing jitter of eight attoseconds. The stabilization performance is obtained by a combination of two different stabilization approaches. In a first step the drift of the CEP is stabilized with a conventional feedback loop by means of controlling the oscillator pump power with an acousto-optic modulator (AOM). In a second step we utilize a recently developed feed-forward type stabilization scheme which has a much higher control bandwith. Here an acousto-optic frequency shifter (AOFS) produces the stabilized output in the first diffraction order. Moreover, we present numerical results on the optimization of the length of the photonic crystal fiber, which is used to generate an octave-spanning spectrum, in order to optimize the sensitivity in the f-to-2f interferometers. PMID:22048346

  13. Fabrication and demonstration of 1 × 8 silicon-silica multi-chip switch based on optical phased array

    NASA Astrophysics Data System (ADS)

    Katayose, Satomi; Hashizume, Yasuaki; Itoh, Mikitaka

    2016-08-01

    We experimentally demonstrated a 1 × 8 silicon-silica hybrid thermo-optic switch based on an optical phased array using a multi-chip integration technique. The switch consists of a silicon chip with optical phase shifters and two silica-based planar lightwave circuit (PLC) chips composed of optical couplers and fiber connections. We adopted a rib waveguide as the silicon waveguide to reduce the coupling loss and increase the alignment tolerance for coupling between silicon and silica waveguides. As a result, we achieved a fast switching response of 81 µs, a high extinction ratio of over 18 dB and a low insertion loss of 4.9-8.1 dB including a silicon-silica coupling loss of 0.5 ± 0.3 dB at a wavelength of 1.55 µm.

  14. Fabrication and demonstration of 1 × 8 silicon–silica multi-chip switch based on optical phased array

    NASA Astrophysics Data System (ADS)

    Katayose, Satomi; Hashizume, Yasuaki; Itoh, Mikitaka

    2016-08-01

    We experimentally demonstrated a 1 × 8 silicon–silica hybrid thermo-optic switch based on an optical phased array using a multi-chip integration technique. The switch consists of a silicon chip with optical phase shifters and two silica-based planar lightwave circuit (PLC) chips composed of optical couplers and fiber connections. We adopted a rib waveguide as the silicon waveguide to reduce the coupling loss and increase the alignment tolerance for coupling between silicon and silica waveguides. As a result, we achieved a fast switching response of 81 µs, a high extinction ratio of over 18 dB and a low insertion loss of 4.9–8.1 dB including a silicon–silica coupling loss of 0.5 ± 0.3 dB at a wavelength of 1.55 µm.

  15. Two-frame phase-shifting interferometry for testing optical surfaces.

    PubMed

    Tian, Chao; Liu, Shengchun

    2016-08-01

    Standard phase-shifting interferometry (PSI) generally requires collecting at least three phase-shifted interferograms to extract the physical quantity being measured. Here, we propose the application of a simple two-frame PSI for the testing of a range of optical surfaces, including flats, spheres, and aspheres. The two-frame PSI extracts modulated phase from two randomly phase-shifted interferograms using a Gram-Schmidt algorithm, and can work in either null testing or non-null testing modes. Since only two interferograms are used for phase demodulation and the phase shift amount can be random, requirements on environmental conditions and phase shifter calibration are greatly relaxed. Experimental results of three different mirrors suggest that the two-frame PSI can achieve comparable measurement precision with conventional multi-frame PSI, but has faster data acquisition speed and less stringent hardware requirements. The proposed two-frame PSI expands the flexibility of PSI and holds great potential in many applications. PMID:27505832

  16. White light phase shifting interferometry and color fringe analysis for the detection of contaminants in water

    NASA Astrophysics Data System (ADS)

    Dubey, Vishesh; Singh, Veena; Ahmad, Azeem; Singh, Gyanendra; Mehta, Dalip Singh

    2016-03-01

    We report white light phase shifting interferometry in conjunction with color fringe analysis for the detection of contaminants in water such as Escherichia coli (E.coli), Campylobacter coli and Bacillus cereus. The experimental setup is based on a common path interferometer using Mirau interferometric objective lens. White light interferograms are recorded using a 3-chip color CCD camera based on prism technology. The 3-chip color camera have lesser color cross talk and better spatial resolution in comparison to single chip CCD camera. A piezo-electric transducer (PZT) phase shifter is fixed with the Mirau objective and they are attached with a conventional microscope. Five phase shifted white light interferograms are recorded by the 3-chip color CCD camera and each phase shifted interferogram is decomposed into the red, green and blue constituent colors, thus making three sets of five phase shifted intererograms for three different colors from a single set of white light interferogram. This makes the system less time consuming and have lesser effect due to surrounding environment. Initially 3D phase maps of the bacteria are reconstructed for red, green and blue wavelengths from these interferograms using MATLAB, from these phase maps we determines the refractive index (RI) of the bacteria. Experimental results of 3D shape measurement and RI at multiple wavelengths will be presented. These results might find applications for detection of contaminants in water without using any chemical processing and fluorescent dyes.

  17. Optical beam forming techniques for phased array antennas

    NASA Technical Reports Server (NTRS)

    Wu, Te-Kao; Chandler, C.

    1993-01-01

    Conventional phased array antennas using waveguide or coax for signal distribution are impractical for large scale implementation on satellites or spacecraft because they exhibit prohibitively large system size, heavy weight, high attenuation loss, limited bandwidth, sensitivity to electromagnetic interference (EMI) temperature drifts and phase instability. However, optical beam forming systems are smaller, lighter, and more flexible. Three optical beam forming techniques are identified as applicable to large spaceborne phased array antennas. They are (1) the optical fiber replacement of conventional RF phased array distribution and control components, (2) spatial beam forming, and (3) optical beam splitting with integrated quasi-optical components. The optical fiber replacement and the spatial beam forming approaches were pursued by many organizations. Two new optical beam forming architectures are presented. Both architectures involve monolithic integration of the antenna radiating elements with quasi-optical grid detector arrays. The advantages of the grid detector array in the optical process are the higher power handling capability and the dynamic range. One architecture involves a modified version of the original spatial beam forming approach. The basic difference is the spatial light modulator (SLM) device for controlling the aperture field distribution. The original liquid crystal light valve SLM is replaced by an optical shuffling SLM, which was demonstrated for the 'smart pixel' technology. The advantages are the capability of generating the agile beams of a phased array antenna and to provide simultaneous transmit and receive functions. The second architecture considered is the optical beam splitting approach. This architecture involves an alternative amplitude control for each antenna element with an optical beam power divider comprised of mirrors and beam splitters. It also implements the quasi-optical grid phase shifter for phase control and grid

  18. Precision phase control for the radio frequency system of K500 superconducting cyclotron at Variable Energy Cyclotron Centre, Kolkata

    SciTech Connect

    Som, Sumit; Ghosh, Surajit; Seth, Sudeshna; Mandal, Aditya; Paul, Saikat; Roy, Suprakash

    2013-11-15

    Variable Energy Cyclotron Centre (VECC) has commissioned K500 Superconducting cyclotron (SCC) based on MSU and Texas A and M university cyclotrons. The radio frequency (RF) system of SCC has been commissioned with the stringent requirement of various RF parameters. The three-phase RF system of Superconducting cyclotron has been developed in the frequency range 9–27 MHz with amplitude and phase stability of 100 ppm and ±0.1°, respectively. The phase control system has the option to change the relative phase difference between any two RF cavities and maintain the phase stability within ±0.1° during round-the-clock cyclotron operation. The said precision phase loop consists of both analogue In-phase/Quadrature modulator to achieve faster response and also Direct Digital Synthesis based phase shifter to achieve wide dynamic range as well. This paper discusses detail insights into the various issues of phase control for the K500 SCC at VECC, Kolkata.

  19. MMIC linear-phase and digital modulators for deep space spacecraft X-band transponder applications

    NASA Technical Reports Server (NTRS)

    Mysoor, Narayan R.; Ali, Fazal

    1991-01-01

    The design concepts, analyses, and development of GaAs monolithic microwave integrated circuit (MMIC) linear-phase and digital modulators for the next generation of space-borne communications systems are summarized. The design approach uses a compact lumped element quadrature hybrid and Metal Semiconductor Field Effect Transistors (MESFET)-varactors to provide low loss and well-controlled phase performance for deep space transponder (DST) applications. The measured results of the MESFET-diode show a capacitance range of 2:1 under reverse bias, and a Q of 38 at 10 GHz. Three cascaded sections of hybrid-coupled reflection phase shifters were modeled and simulations performed to provide an X-band (8415 +/- 50 MHz) DST phase modulator with +/- 2.5 radians of peak phase deviation. The modulator will accommodate downlink signal modulation with composite telemetry and ranging data, with a deviation linearity tolerance of +/- 8 percent and insertion loss of less than 8 +/- 0.5 dB. The MMIC digital modulator is designed to provide greater than 10 Mb/s of bi-phase modulation at X-band.

  20. Precision phase control for the radio frequency system of K500 superconducting cyclotron at Variable Energy Cyclotron Centre, Kolkata.

    PubMed

    Som, Sumit; Ghosh, Surajit; Seth, Sudeshna; Mandal, Aditya; Paul, Saikat; Roy, Suprakash

    2013-11-01

    Variable Energy Cyclotron Centre (VECC) has commissioned K500 Superconducting cyclotron (SCC) based on MSU and Texas A&M university cyclotrons. The radio frequency (RF) system of SCC has been commissioned with the stringent requirement of various RF parameters. The three-phase RF system of Superconducting cyclotron has been developed in the frequency range 9-27 MHz with amplitude and phase stability of 100 ppm and ±0.1°, respectively. The phase control system has the option to change the relative phase difference between any two RF cavities and maintain the phase stability within ±0.1° during round-the-clock cyclotron operation. The said precision phase loop consists of both analogue In-phase∕Quadrature modulator to achieve faster response and also Direct Digital Synthesis based phase shifter to achieve wide dynamic range as well. This paper discusses detail insights into the various issues of phase control for the K500 SCC at VECC, Kolkata.

  1. Relative carrier-envelope phase stabilization of hybridly synchronized ultrafast Yb and Er fiber-laser systems with the feed-forward scheme.

    PubMed

    Fong, Bo-Jyun; Lin, Wei-Ting; Wu, Shang-Ying; Peng, Jin-Long; Hsiang, Wei-Wei; Lai, Yinchieh

    2015-03-15

    Stabilization of the relative carrier-envelope (CE) phase for hybridly synchronized two-color fs Yb and Er fiber-laser systems is demonstrated for the first time by utilizing the feed-forward scheme based on an acousto-optic frequency shifter. The slow drift issues arising from the feed-forward scheme are solved by adding the in-loop relative CE frequency coarse stabilization via modulating the laser pump current. Sub-fs timing locking between the two-color pulses is still maintained due to the fast response and large locking range of hybrid synchronization. The approach provides an alternative way to obtain phase-stable synchronized two-color pulses with higher pulse energies. PMID:25768158

  2. Method and apparatus for self-calibration and phasing of array antenna

    NASA Technical Reports Server (NTRS)

    Wu, C. (Inventor)

    1984-01-01

    A technique for self-calibrating and phasing a lens-feed array antenna, while normal operation is stopped, utilizes reflected energy of a continuous and coherent wave broadcast by a transmitter through a central feed while a phase controller advances the phase angles of reciprocal phase shifters in radiation electronics of the array elements at different rates to provide a distinct frequency modulation of electromagnetic wave energy returned by reflection in one mode and leakage in another mode from the radiation electronics of each array element. The composite return signal received by a synchronous receiver goes through a Fourier transform processing system and produces a response function for each antenna element. Compensation of the phase angles for the antenna elements required to conform the antenna response to a precomputed array pattern is derived from the reciprocal square root of the response functions for the antenna elements which, for a rectangular array of NXM elements, is a response function T(n,m). A third mode of calibration uses an external pilot tone from a separate antenna element. Respective responses are thus obtained from the three modes of calibration.

  3. Coronagraph Focal-Plane Phase Masks Based on Photonic Crystal Technology: Recent Progress and Observational Strategy

    NASA Technical Reports Server (NTRS)

    Murakami, Naoshi; Nishikawa, Jun; Sakamoto, Moritsugu; Ise, Akitoshi; Oka, Kazuhiko; Baba, Naoshi; Murakami, Hiroshi; Tamura, Motohide; Traub, Wesley A.; Mawet, Dimitri; Moody, Dwight C.; Kern, Brian D.; Trauger, John T.; Serabyn, Eugene; Hamaguchi, Shoki; Oshiyama, Fumika

    2012-01-01

    Photonic crystal, an artificial periodic nanostructure of refractive indices, is one of the attractive technologies for coronagraph focal-plane masks aiming at direct imaging and characterization of terrestrial extrasolar planets. We manufactured the eight-octant phase mask (8OPM) and the vector vortex mask (VVM) very precisely using the photonic crystal technology. Fully achromatic phase-mask coronagraphs can be realized by applying appropriate polarization filters to the masks. We carried out laboratory experiments of the polarization-filtered 8OPM coronagraph using the High-Contrast Imaging Testbed (HCIT), a state-of-the-art coronagraph simulator at the Jet Propulsion Laboratory (JPL). We report the experimental results of 10-8-level contrast across several wavelengths over 10% bandwidth around 800nm. In addition, we present future prospects and observational strategy for the photonic-crystal mask coronagraphs combined with differential imaging techniques to reach higher contrast. We proposed to apply a polarization-differential imaging (PDI) technique to the VVM coronagraph, in which we built a two-channel coronagraph using polarizing beam splitters to avoid a loss of intensity due to the polarization filters. We also proposed to apply an angular-differential imaging (ADI) technique to the 8OPM coronagraph. The 8OPM/ADI mode avoids an intensity loss due to a phase transition of the mask and provides a full field of view around central stars. We present results of preliminary laboratory demonstrations of the PDI and ADI observational modes with the phase-mask coronagraphs.

  4. Moon Phases

    ERIC Educational Resources Information Center

    Riddle, Bob

    2010-01-01

    When teaching Moon phases, the focus seems to be on the sequence of Moon phases and, in some grade levels, how Moon phases occur. Either focus can sometimes be a challenge, especially without the use of models and observations of the Moon. In this month's column, the author describes some of the lessons that he uses to teach the phases of the Moon…

  5. Achromatic Cooling Channel with Li Lenses

    SciTech Connect

    Balbekov, V.

    2002-04-29

    A linear cooling channel with Li lenses, solenoids, and 201 MHz RF cavities is considered. A special lattice design is used to minimize chromatic aberrations by suppression of several betatron resonances. Transverse emittance of muon beam decreases from 2 mm to 0.5 mm at the channel of about 110 m length. Longitudinal heating is modest, therefore transmission of the channel is rather high: 96% without decay and 90% with decay. Minimal beam emittance achievable by similar channel estimated as about 0.25 mm at surface field of Li lenses 10 T.

  6. Achromatic illumination system for small targets

    DOEpatents

    Sigler, Robert D.

    1979-01-01

    A pair of light beams is directed to provide illumination that is substantially uniform from all directions on a small target by a system comprising a pair of corrector windows, a pair of planar reflecting surfaces, a pair of paraboloidal mirrors and a reflecting mirror cavity. The components are arranged so that each of the beams passes through a corrector and is reflected from the planar surface to the paraboloidal mirror, from which it is focused through a hole in the planar surface to the interior of the cavity. The surface of the interior portion of the cavity is shaped to reflect the focused beam three times before the focused reflected beam strikes the target.

  7. Plasmonic All-Optical Tunable Wavelength Shifter

    SciTech Connect

    Flugel, B.; Macararenhas, A.; Snoke, D. W.; Pfeiffer, L. N.; West, K.

    2007-12-01

    At present, wavelength-division-multiplexed fibre lines routinely operate at 10 Gbit s{sup -1} per channel. The transition from static-path networks to true all-optical networks encompassing many nodes, in which channels are added/dropped and efficiently reassigned, will require improved tools for all-optical wavelength shifting. Specifically, one must be able to shift the carrier wavelength (frequency) of an optical data signal over tens of nanometres (a THz range) without the bottleneck of electrical conversion. Popular approaches to this problem make use of the nonlinear interaction between two wavelengths within a semiconductor optical amplifier whereas more novel methods invoke terahertz-frequency electro-optic modulation and polaritons. Here we outline the principles and demonstrate the use of optically excited plasmons as a tunable frequency source that can be mixed with a laser frequency through Raman scattering. The scheme is all-optical and enables dynamical control of the output carrier wavelength simply by varying the power of a control laser.

  8. Advanced process with magnetically enhanced RIE for phase-shifting mask fabrication

    NASA Astrophysics Data System (ADS)

    Aoyama, Satoshi; Kusunose, Haruhiko; Hanazaki, Minoru; Yoshioka, Nobuyuki; Watakabe, Yaichiro; Hayashi, Atsushi; Isao, Akihiko; Tokoro, Yasuo

    1993-08-01

    Phase-shifting needs the critical dimension (CD) accuracy to be less than 0.05 micrometers for the metal and shifter pattern on a phase-shifting mask. Thus we have investigated a new etching process using magnetically enhanced reactive ion etching (MERIE). A magnetic field was provided by two pairs of solenoid coils outside the chamber. By using this MERIE system, the etching characteristics of chromium (Cr) and spin on glass (SOG) were evaluated. A Cl2 and O2 gas mixture was used for Cr etching. The etching selectivity had a maximum when the concentration of O2 was 20%. The etching selectivity increased with an increase in the magnetic field and gas pressure as well as with a decrease in the rf power. High etching selectivity and anisotropic etching features were obtained when the magnetic field was 100 G, the gas pressure 10 - 30 Pa, and the rf power density 0.18 - 0.22 W/cm2. Phase-shifting masks fabricated with this system show a CD accuracy of better than 0.05 micrometers , so 64 MB DRAM phase-shifting masks can be successfully fabricated with this MERIE system.

  9. Imaging performance of attenuated phase-shift mask using coherent scattering microscope

    NASA Astrophysics Data System (ADS)

    Lee, Jae Uk; Jeong, SeeJun; Hong, Seong Chul; Lee, Seung Min; Ahn, Jinho

    2014-03-01

    The half-tone phase shift mask (PSM) has been suggested for better imaging performances like image contrast, NILS and H-V bias compared to the binary mask (BIM) in EUV lithography. In this paper, we measured imaging performance of a fabricated half-tone attenuated PSM with Coherent Scattering Microscopy (CSM) and the results were compared with simulation data obtained by EM-suite tool. We prepared a half-tone attenuated PSM which has 12.7% reflectivity and 180° phase shift with absorber stack of 16.5mn-thick TaN absorber and 24nm-thick Mo phase shifter. With CSM, an actinic inspection tool, we measured the imaging properties of PSM. The diffraction efficiencies of BIM were measured as 31%, 36%, and 44% for 88 nm, 100 nm, and 128 nm mask CD, respectively, while those of PSM were measured as 45%, 62%, and 81%. Also the aerial image at wafer level obtained by CSM with high volume manufacturing tool's (HVM) illumination condition (NA=0.33, σ=0.9) showed higher image contrast and NILS with phase shift effect. And the measured data were consistent with the simulation data.

  10. T/R module development for large aperture L-band phased array

    NASA Technical Reports Server (NTRS)

    Chamberlain, Neil; Andricos, Constantine; Kumley, Kendra; Berkun, Andrew; Hodges, Richard; Spitz, Suzanne

    2004-01-01

    This paper describes a transmit / receive (T/R) module for a large L-band space based radar active phased array being developed at JPL. Electrical performance and construction techniques are described, with emphasis on the former. The T/R modules have a bandwidth of more than 80 MHz centered at 1260MHz and support dual, switched polarizations. Phase and amplitude are controlled by a 6-bit phase shifter and a 6-bit attenuator, respectively. The transmitter power amplifier generates 2.4 W into a nominal 50 ohm load with 36% overall efficiency. The receiver noise figure is 4.4 dB including all front-end losses. The module weighs 32 g and has a footprint of 8 cm x 4.5 cm. Fourteen of these T/R modules were fabricated at the JPL Pick-and-Place Facility and were tested using a computer-controlled measurement facility developed at JPL. Calibrated performance of this set of T/R modules is presented and shows good agreement with design predictions.

  11. PHASE DETECTOR

    DOEpatents

    Kippenhan, D.O.

    1959-09-01

    A phase detector circuit is described for use at very high frequencies of the order of 50 megacycles. The detector circuit includes a pair of rectifiers inverted relative to each other. One voltage to be compared is applied to the two rectifiers in phase opposition and the other voltage to be compared is commonly applied to the two rectifiers. The two result:ng d-c voltages derived from the rectifiers are combined in phase opposition to produce a single d-c voltage having amplitude and polarity characteristics dependent upon the phase relation between the signals to be compared. Principal novelty resides in the employment of a half-wave transmission line to derive the phase opposing signals from the first voltage to be compared for application to the two rectifiers in place of the transformer commonly utilized for such purpose in phase detector circuits for operation at lower frequency.

  12. RF phase stability in the 100-MeV proton linac operation

    NASA Astrophysics Data System (ADS)

    Seol, Kyung-Tae

    2015-02-01

    The 100-MeV proton linac of the Korea multi-purpose accelerator complex (KOMAC) has been operated to provide a proton beam to users. The 100-MeV linac consists of a 3-MeV radio-frequency quadrupole accelerator (RFQ), four 20-MeV drift-tube linac (DTL) tanks, two medium-energy beam-transmitter (MEBT) tanks, and seven 100-MeV DTL tanks. The requirements of the field stability are within ±1% in RF amplitude and ±1 degree in RF phase. The RF phase stability is influenced by a RF reference line, RF transmission lines, and a RF control system. The RF reference signal is chosen to be a 300-MHz local oscillator (LO) signal, and a rigid copper coaxial line with temperature control was installed for an RF reference distribution. A phase stability of ±0.1 degrees was measured under a temperature change of ±0.1 °C. A digital feedback control system with a field-programmable gate-array (FPGA) module was adopted for a high RF stability. The RF phase was maintained within ±0.1 degrees with a dummy cavity and was within ±0.3 degrees at RFQ operation. In the case of the 20-MeV DTL tanks, one klystron drives 4 tanks, and the input phases of 4 tanks were designed to be in phase. The input phases of 4 tanks were fixed within ±1 degree by adjusting a phase shifter in each waveguide.

  13. Advanced noise reduction techniques for ultra-low phase noise optical-to-microwave division with femtosecond fiber combs.

    PubMed

    Zhang, Wei; Xu, Zhenyu; Lours, Michel; Boudot, Rodolphe; Kersalé, Yann; Luiten, Andre N; Le Coq, Yann; Santarelli, Giorgio

    2011-05-01

    We report what we believe to be the lowest phase noise optical-to-microwave frequency division using fiber-based femtosecond optical frequency combs: a residual phase noise of -120 dBc/Hz at 1 Hz offset from an 11.55 GHz carrier frequency. Furthermore, we report a detailed investigation into the fundamental noise sources which affect the division process itself. Two frequency combs with quasi-identical configurations are referenced to a common ultrastable cavity laser source. To identify each of the limiting effects, we implement an ultra-low noise carrier-suppression measurement system, which avoids the detection and amplification noise of more conventional techniques. This technique suppresses these unwanted sources of noise to very low levels. In the Fourier frequency range of ∼200 Hz to 100 kHz, a feed-forward technique based on a voltage-controlled phase shifter delivers a further noise reduction of 10 dB. For lower Fourier frequencies, optical power stabilization is implemented to reduce the relative intensity noise which causes unwanted phase noise through power-to-phase conversion in the detector. We implement and compare two possible control schemes based on an acousto-optical modulator and comb pump current. We also present wideband measurements of the relative intensity noise of the fiber comb. PMID:21622045

  14. Phase Sensor for Aligning a Segmented Telescope Mirror

    NASA Technical Reports Server (NTRS)

    Stahl, Philip; Walker, Chanda Barlett

    2006-01-01

    A phase sensor has been developed for use in aligning a segmented telescope mirror to within a fraction of a wavelength in piston. (As used here, piston signifies displacement of a mirror segment along the optical axis of the telescope.) Such precise alignment is necessary in order to realize the full benefit of the large aperture achievable through segmentation. This phase sensor is achromatic. It is based on two-wavelength shearing interferometry, and can be modified to utilize an extended or broad-band (e.g., white) light source. The sensor optics include a ruled diffraction grating and an imaging lens. The sensor can measure the piston shift between segments as well as aberrations of the segments. It can measure the surface error of an individual segment, making it possible to compensate for the error with optimal amount(s) of piston and/or tilt. The precise capture range of the sensor depends partly on the telescope design; the largest relative piston shifts measurable by use of this sensor are of the order of 100 m. The accuracy of the sensor also depends partly on the telescope design; in general, the accuracy is sufficient to enable alignment to within approximately half a wavelength. The interferometric image is digitized and processed by a simple algorithm in real time, and the output of the algorithm can be used to maintain alignment in real time, even in the presence of atmospheric turbulence. The sensor is robust. Through calibration, it can be made insensitive to (and, hence, tolerant of) misalignments and aberrations of its own optics, most aberrations of the telescope as a whole (in contradistinction to aberrations of individual segments), and most aberrations introduced by atmospheric turbulence

  15. Performance characterization of a broadband vector Apodizing Phase Plate coronagraph.

    PubMed

    Otten, Gilles P P L; Snik, Frans; Kenworthy, Matthew A; Miskiewicz, Matthew N; Escuti, Michael J

    2014-12-01

    One of the main challenges for the direct imaging of planets around nearby stars is the suppression of the diffracted halo from the primary star. Coronagraphs are angular filters that suppress this diffracted halo. The Apodizing Phase Plate coronagraph modifies the pupil-plane phase with an anti-symmetric pattern to suppress diffraction over a 180 degree region from 2 to 7 λ/D and achieves a mean raw contrast of 10(-4) in this area, independent of the tip-tilt stability of the system. Current APP coronagraphs implemented using classical phase techniques are limited in bandwidth and suppression region geometry (i.e. only on one side of the star). In this paper, we introduce the vector-APP (vAPP) whose phase pattern is implemented through the vector phase imposed by the orientation of patterned liquid crystals. Beam-splitting according to circular polarization states produces two, complementary PSFs with dark holes on either side. We have developed a prototype vAPP that consists of a stack of three twisting liquid crystal layers to yield a bandwidth of 500 to 900 nm. We characterize the properties of this device using reconstructions of the pupil-plane pattern, and of the ensuing PSF structures. By imaging the pupil between crossed and parallel polarizers we reconstruct the fast axis pattern, transmission, and retardance of the vAPP, and use this as input for a PSF model. This model includes aberrations of the laboratory set-up, and matches the measured PSF, which shows a raw contrast of 10(-3.8) between 2 and 7 λ/D in a 135 degree wedge. The vAPP coronagraph is relatively easy to manufacture and can be implemented together with a broadband quarter-wave plate and Wollaston prism in a pupil wheel in high-contrast imaging instruments. The liquid crystal patterning technique permits the application of extreme phase patterns with deeper contrasts inside the dark holes, and the multilayer liquid crystal achromatization technique enables unprecedented spectral bandwidths

  16. All-optical sensitive phase shifting based on nonlinear out-of-plane coupling through 1-D slab photonic crystal with a layer of graphene.

    PubMed

    Asadi, Reza; Ouyang, Zhengbiao; Yu, Quanqiang; Ruan, Shuangchen

    2014-06-16

    We realize all-optical sensitive phase shifting based on nonlinear out-of-plane coupling to a slab waveguide through Fano resonance of a slab 1-D photonic crystal (PhC). We use a graphene layer as the nonlinear material and change its refractive index by the input light intensity through Kerr nonlinear effect to obtain a shift in the Fano resonance frequency. The Fano resonance and self-focusing effect lead to light-intensity enhancement on the graphene in the PhC, reinforcing the nonlinear effect of refractive index in the graphene. Through finite-difference time-domain simulation, we demonstrate that the phase changing sensitivity obtained can be 4 orders higher than that by a single graphene under the same input light intensity. Moreover the threshold pump intensity for all-optical sensitive phase shifting in the coupled light to the waveguide is as low as ~4 MW per square centimeter. The results are applicable in micro optical integrated circuits for phase shifters, phase modulators, power limiters, and phase logic elements for optical computation, digital phase shift keying in communication systems, and non-contact sensitive signal detectors.

  17. Fabrication and characterization of BSTO and nonferroelectric oxide composites for use in phased array antennas and other electronic devices

    SciTech Connect

    Sengupta, L.C.; Ngo, E.; O`Day, M.E.; Stowell, S.; Lancto, R.

    1994-12-01

    A ceramic ferroelectric phase shifting device has been demonstrated using Ba(1-x)Sr(x)TiO3 (BSTO) ceramics. As a part of an effort to optimize the electronic device performance in the phase shifter, various composites of BSTO combined with other nonelectrically active oxide ceramics have been formulated. In general, the composites have reduced dielectric constants, epsilon`, where epsilon = epsilon` = i(epsilon)`, and loss tangents, tan delta. The low dielectric constant and low loss tangent reduce the overall impedance mismatch and the insertion loss of the device, In addition, the overall tunability, change in the dielectric constant with applied voltage, is maintained at a relatively high level. The combination of electronic properties of these materials offer substantially higher operating frequencies, 10 GHz and above. Another application for one of the composites is for use as a capacitor-varistor surge protector. The microstructures including grain size and phase analysis have been examined using SEM and X-ray diffraction. The analysis of the phase formation, compositional variations, and grain size will be related to the electronic properties of the materials.

  18. Venus Phasing.

    ERIC Educational Resources Information Center

    Riddle, Bob

    1997-01-01

    Presents a science activity designed to introduce students to the geocentric and heliocentric models of the universe. Helps students discover why phase changes on Venus knocked Earth out of the center of the universe. (DKM)

  19. Phase Change

    NASA Technical Reports Server (NTRS)

    Hasan, Mohammad M.

    2004-01-01

    Recent workshops to define strategic research on critical issues in microgravity fluids and transport phenomena in support of mission orientated needs of NASA and many technical conferences over the years in support of fundamental research targeting NASA's long range missions goal have identified several phase change processes needed to design advanced space and planetary based systems for long duration operations Recommendation noted that phase change processes are profoundly affected by gravitational environment.

  20. Cantilever RF-MEMS for monolithic integration with phased array antennas on a PCB

    NASA Astrophysics Data System (ADS)

    Aguilar-Armenta, C. J.; Porter, S. J.

    2015-12-01

    This article presents the development and operation of a novel electrostatic metal-to-metal contact cantilever radio-frequency microelectromechanical system (RF-MEMS) switch for monolithic integration with microstrip phased array antennas (PAAs) on a printed circuit board. The switch is fabricated using simple photolithography techniques on a Rogers 4003c substrate, with a footprint of 200 µm × 100 µm, based on a 1 µm-thick copper cantilever. An alternative wet-etching technique for effectively releasing the cantilever is described. Electrostatic and electromagnetic measurements show that the RF-MEMS presents an actuation voltage of 90 V for metal-to-metal contact, an isolation of -8.7 dB, insertion loss of -2.5 dB and a return loss of -15 dB on a 50 Ω microstrip line at 12.5 GHz. For proof-of-concept, a beam-steering 2 × 2 microstrip PAA, based on two 1-bit phase shifters suitable for the monolithic integration of the RF-MEMS, has been designed and measured at 12.5 GHz. Measurements show that the beam-steering system presents effective radiation characteristics with scanning capabilities from broadside towards 29° in the H-plane.

  1. Improved synthetic-heterodyne Michelson interferometer vibrometer using phase and gain control feedback.

    PubMed

    Galeti, José Henrique; Kitano, Cláudio; Connelly, Michael J

    2015-12-10

    Synthetic-heterodyne demodulation is a useful technique for dynamic displacement and velocity measurement using interferometric sensors as it can provide an output signal which is immune to interferometric drift. With the advent of cost effective, high-speed real-time signal processing systems and software, processing of the complex signals encountered in interferometry has become more feasible. In conventional synthetic-heterodyne demodulation schemes, to obtain the dynamic displacement or vibration of the object under test requires knowledge of the interferometer visibility and also the argument of two Bessel functions. In this paper, a new synthetic-heterodyne demodulation method is described leading to an expression for the dynamic displacement and velocity of the object under test that is significantly less sensitive to the received optical power. In addition, the application of two independent phase and gain feedback loops is used to compensate for the nonideal gain and phase response of the anti-aliasing filter required for the signal acquisition of the received wideband interferometer signal. The efficacy of the improved system is demonstrated by measuring the displacement sensitivity frequency response and linearity of a Piezoelectric Mirror-Shifter (PMS) over a range of 200 Hz-9 kHz. In addition, the system is used to measure the response of the PMS to triangular and impulse type stimuli. The experimental results show excellent agreement with measurements taken using two independent industry standard calibration methods. PMID:26836865

  2. The plateau phase of gamma-ray burst afterglows in the thick-shell scenario

    NASA Astrophysics Data System (ADS)

    Leventis, K.; Wijers, R. A. M. J.; van der Horst, A. J.

    2014-01-01

    We present analytic calculations of synchrotron radiation from the forward and the reverse shock of gamma-ray burst blast waves, in the thick-shell scenario (i.e. when the reverse shock is relativistic). We show that this scenario can naturally account for the plateau phase, observed early in the afterglows of about half the bursts detected by Swift. We generalize our approach to include power-law luminosity of the central engine and show that when radiation from both regions (forward and reverse shock) is taken into account, a wide range of possibilities emerge, including chromatic and achromatic breaks, frequency-dependent spectral evolution during the injection break and widely varying decay indices in different bands. For both the forward and the reverse shock, we derive formulas for the spectral parameters and the observed flux in different power-law segments of the spectrum, as a function of observer time. We explore the Fb-tb relation (between the observed time of the end of the plateau phase and the flux at that point) in the framework of the presented model and show that model predictions favour the reverse shock as the dominant source of emission in both optical and X-rays. As case studies, we present simultaneous fits to X-ray and optical/IR afterglow data of GRB 080928 and GRB 090423. We identify the end of the plateau phase with the cessation of energy injection and infer the corresponding upper limits to central-engine activity, which are about 1 h for the former and 1.5 h for the latter. We conclude that smooth energy injection through the reverse shock is a plausible explanation for the plateau phase of gamma-ray burst afterglows. During that phase, radiation from the reverse shock is likely to be important, or even dominant, and should be taken into account when fitting model parameters to observations.

  3. The Four-Quadrant Phase-Mask Coronagraph. I. Principle

    NASA Astrophysics Data System (ADS)

    Rouan, D.; Riaud, P.; Boccaletti, A.; Clénet, Y.; Labeyrie, A.

    2000-11-01

    We describe a new type of coronagraph, based on the principle of a phase mask as proposed by Roddier and Roddier a few years ago but using an original mask design found by one of us (D. R.), a four-quadrant binary phase mask (0, π) covering the full field of view at the focal plane. The mutually destructive interferences of the coherent light from the main source produce a very efficient nulling. The computed rejection rate of this coronagraph appears to be very high since, when perfectly aligned and phase-error free, it could in principle reduce the total amount of light from the bright source by a factor of 108, corresponding to a gain of 20 mag in brightness at the location of the first Airy ring, relative to the Airy peak. In the real world the gain is of course reduced by a strong factor, but nulling is still performing quite well, provided that the perturbation of the phase, for instance, due to the Earth's atmosphere, is efficiently corrected by adaptive optics. We show from simulations that a detection at a contrast of 10 mag between a star and a faint companion is achievable in excellent conditions, while 8 mag appears routinely feasible. This coronagraph appears less sensitive to atmospheric turbulence and has a larger dynamic range than other recently proposed nulling techniques: the phase-mask coronagraph (by Roddier and Roddier) or the Achromatic Interfero-Coronagraph (by Gay and Rabbia). We present the principle of the four-quadrant coronagraph and results of a first series of simulations. We compare those results with theoretical performances of other devices. We briefly analyze the different limitations in space or ground-based observations, as well as the issue of manufacturing the device. We also discuss several ways to improve the detection of a faint companion around a bright object. We conclude that, with respect to previous techniques, an instrument equipped with this coronagraph should have better performance and even enable the imaging of

  4. Absolute frequency synthesis of pulsed coherent light waves through phase-modulation active optical feedback.

    PubMed

    Shimizu, K; Horiguchi, T; Koyamada, Y

    1996-11-15

    A novel method for the broadband absolute frequency synthesis of pulsed coherent lightwaves is demonstrated. It is based on pulse recirculation around an active optical feedback ring containing a delay-line fiber, an external phase modulator, an acousto-optic frequency shifter (AOFS), and a high-finesse Fabry-Perot étalon. The modulation frequency F(M) and the frequency shift F(AO) that are due to AOFS are designed so that their sum or difference equals the free-spectral range of the étalon and F(AO) is set at larger than the half-width at full maximum of its resonant peaks. If one of the peak frequencies is tuned to the frequency of the initial pulse, the frequency of the recirculating pulse jumps to the next peak for each round trip. In the experiment the absolute frequency is synthesized over a frequency span of 700 GHz around the initial stabilized frequency of the master laser.

  5. Responses of macaque ganglion cells to the relative phase of heterochromatically modulated lights.

    PubMed Central

    Smith, V C; Lee, B B; Pokorny, J; Martin, P R; Valberg, A

    1992-01-01

    1. We measured the response of macaque ganglion cells to sinusoidally modulated red and green lights as the relative phase, theta, of the lights was varied. 2. At low frequencies, red-green ganglion cells of the parvocellular (PC-) pathway with opponent inputs from middle-wavelength sensitive (M-) and long-wavelength sensitive (L-) cones were minimally sensitive to luminance modulation (theta = 0 deg) and maximally sensitive to chromatic modulation (theta = 180 deg). With increasing frequency, the phase, theta, of minimal amplitude gradually changed, in opposite directions for cells with M- and L-cone centres. 3. At high frequencies (at and above 20 Hz), phasic cells of the magnocellular (MC-) pathway were maximally responsive when theta approximately 0 deg and minimally responsive when theta approximately 180 deg, as expected from an achromatic mechanism. At lower frequencies, the phase of minimal response shifted, for both on- and off-centre cells, to values of theta intermediate between 0 and 180 deg. This phase asymmetry was absent if the centre alone was stimulated with a small field. 4. For PC-pathway cells, it was possible to provide an account of response phase as a function of theta, using a model involving three parameters; phases of the L- and M-cone mechanisms and a L/M cone weighting term. For red-green cells, the phase parameters were monotonically related to temporal frequency and revealed a centre-surround phase difference. The phase difference was linear with a slope of 1-3 deg Hz-1. If this represents a latency difference, it would be 3-8 ms. Otherwise, temporal properties of the M- and L-cones appeared similar if not identical. By addition of a scaling term, the model could be extended to give an adequate account of the amplitude of responses. 5. We were able to activate selectively the surrounds of cells with short-wavelength (S-) cone input to their centres, and so were able to assess L/M cone weighting to the surround. M- and L-cone inputs

  6. Laboratory implementation of edge illumination X-ray phase-contrast imaging with energy-resolved detectors

    NASA Astrophysics Data System (ADS)

    Diemoz, P. C.; Endrizzi, M.; Vittoria, F. A.; Hagen, C. K.; Kallon, G.; Basta, D.; Marenzana, M.; Delogu, P.; Vincenzi, A.; De Ruvo, L.; Spandre, G.; Brez, A.; Bellazzini, R.; Olivo, A.

    2015-03-01

    Edge illumination (EI) X-ray phase-contrast imaging (XPCI) has potential for applications in different fields of research, including materials science, non-destructive industrial testing, small-animal imaging, and medical imaging. One of its main advantages is the compatibility with laboratory equipment, in particular with conventional non-microfocal sources, which makes its exploitation in normal research laboratories possible. In this work, we demonstrate that the signal in laboratory implementations of EI can be correctly described with the use of the simplified geometrical optics. Besides enabling the derivation of simple expressions for the sensitivity and spatial resolution of a given EI setup, this model also highlights the EI's achromaticity. With the aim of improving image quality, as well as to take advantage of the fact that all energies in the spectrum contribute to the image contrast, we carried out EI acquisitions using a photon-counting energy-resolved detector. The obtained results demonstrate that this approach has great potential for future laboratory implementations of EI.

  7. L-Band Transmit/Receive Module for Phase-Stable Array Antennas

    NASA Technical Reports Server (NTRS)

    Andricos, Constantine; Edelstein, Wendy; Krimskiy, Vladimir

    2008-01-01

    Interferometric synthetic aperture radar (InSAR) has been shown to provide very sensitive measurements of surface deformation and displacement on the order of 1 cm. Future systematic measurements of surface deformation will require this capability over very large areas (300 km) from space. To achieve these required accuracies, these spaceborne sensors must exhibit low temporal decorrelation and be temporally stable systems. An L-band (24-cmwavelength) InSAR instrument using an electronically steerable radar antenna is suited to meet these needs. In order to achieve the 1-cm displacement accuracy, the phased array antenna requires phase-stable transmit/receive (T/R) modules. The T/R module operates at L-band (1.24 GHz) and has less than 1- deg absolute phase stability and less than 0.1-dB absolute amplitude stability over temperature. The T/R module is also high power (30 W) and power efficient (60-percent overall efficiency). The design is currently implemented using discrete components and surface mount technology. The basic T/R module architecture is augmented with a calibration loop to compensate for temperature variations, component variations, and path loss variations as a function of beam settings. The calibration circuit consists of an amplitude and phase detector, and other control circuitry, to compare the measured gain and phase to a reference signal and uses this signal to control a precision analog phase shifter and analog attenuator. An architecture was developed to allow for the module to be bidirectional, to operate in both transmit and receive mode. The architecture also includes a power detector used to maintain a transmitter power output constant within 0.1 dB. The use of a simple, stable, low-cost, and high-accuracy gain and phase detector made by Analog Devices (AD8302), combined with a very-high efficiency T/R module, is novel. While a self-calibrating T/R module capability has been sought for years, a practical and cost-effective solution has

  8. Fully Printed High-Frequency Phased-Array Antenna on Flexible Substrate

    NASA Technical Reports Server (NTRS)

    Chen, Yihong; Lu, Xuejun

    2010-01-01

    To address the issues of flexible electronics needed for surface-to-surface, surface-to-orbit, and back-to-Earth communications necessary for manned exploration of the Moon, Mars, and beyond, a room-temperature printing process has been developed to create active, phased-array antennas (PAAs) on a flexible Kapton substrate. Field effect transistors (FETs) based on carbon nanotubes (CNTs), with many unique physical properties, were successfully proven feasible for phased-array antenna systems. The carrier mobility of an individual CNT is estimated to be at least 100,000 sq cm/V(dot)s. The CNT network in solution has carrier mobility as high as 46,770 sq cm/V(dot)s, and has a large current-density carrying capacity of approx. 1,000 mA/sq cm , which corresponds to a high carrying power of over 2,000 mW/ sq cm. Such high carrier mobility, and large current carrying capacity, allows the achievement of high-speed (>100 GHz), high-power, flexible electronic circuits that can be monolithically integrated on NASA s active phasedarray antennas for various applications, such as pressurized rovers, pressurized habitats, and spacesuits, as well as for locating beacon towers for lunar surface navigation, which will likely be performed at S-band and attached to a mobile astronaut. A fully printed 2-bit 2-element phasedarray antenna (PAA) working at 5.6 GHz, incorporating the CNT FETs as phase shifters, is demonstrated. The PAA is printed out at room temperature on 100-mm thick Kapton substrate. Four CNT FETs are printed together with microstrip time delay lines to function as a 2-bit phase shifter. The FET switch exhibits a switching speed of 0.2 ns, and works well for a 5.6-GHz RF signal. The operating frequency is measured to be 5.6 GHz, versus the state-of-the-art flexible FET operating frequency of 52 MHz. The source-drain current density is measured to be over 1,000 mA/sq cm, while the conventional organic FETs, and single carbon nanotube-based FETs, are typically in the m

  9. Oblique electron-cyclotron-emission radial and phase detector of rotating magnetic islands applied to alignment and modulation of electron-cyclotron-current-drive for neoclassical tearing mode stabilization

    SciTech Connect

    Volpe, F.; Austin, M. E.; Campbell, G.; Deterly, T.

    2012-10-15

    A two channel oblique electron cyclotron emission (ECE) radiometer was installed on the DIII-D tokamak and interfaced to four gyrotrons. Oblique ECE was used to toroidally and radially localize rotating magnetic islands and so assist their electron cyclotron current drive (ECCD) stabilization. In particular, after manipulations operated by the interfacing analogue circuit, the oblique ECE signals directly modulated the current drive in synch with the island rotation and in phase with the island O-point, for a more efficient stabilization. Apart from the different toroidal location, the diagnostic view is identical to the ECCD launch direction, which greatly simplified the real-time use of the signals. In fact, a simple toroidal extrapolation was sufficient to lock the modulation to the O-point phase. This was accomplished by a specially designed phase shifter of nearly flat response over the 1-7 kHz range. Moreover, correlation analysis of two channels slightly above and below the ECCD frequency allowed checking the radial alignment to the island, based on the fact that for satisfactory alignment the two signals are out of phase.

  10. Oblique electron-cyclotron-emission radial and phase detector of rotating magnetic islands applied to alignment and modulation of electron-cyclotron-current-drive for neoclassical tearing mode stabilization.

    PubMed

    Volpe, F; Austin, M E; Campbell, G; Deterly, T

    2012-10-01

    A two channel oblique electron cyclotron emission (ECE) radiometer was installed on the DIII-D tokamak and interfaced to four gyrotrons. Oblique ECE was used to toroidally and radially localize rotating magnetic islands and so assist their electron cyclotron current drive (ECCD) stabilization. In particular, after manipulations operated by the interfacing analogue circuit, the oblique ECE signals directly modulated the current drive in synch with the island rotation and in phase with the island O-point, for a more efficient stabilization. Apart from the different toroidal location, the diagnostic view is identical to the ECCD launch direction, which greatly simplified the real-time use of the signals. In fact, a simple toroidal extrapolation was sufficient to lock the modulation to the O-point phase. This was accomplished by a specially designed phase shifter of nearly flat response over the 1-7 kHz range. Moreover, correlation analysis of two channels slightly above and below the ECCD frequency allowed checking the radial alignment to the island, based on the fact that for satisfactory alignment the two signals are out of phase.

  11. Interferometric phase-contrast X-ray CT imaging of VX2 rabbit cancer at 35keV X-ray energy

    NASA Astrophysics Data System (ADS)

    Takeda, Tohoru; Wu, Jin; Tsuchiya, Yoshinori; Yoneyama, Akio; Lwin, Thet-Thet; Hyodo, Kazuyuki; Itai, Yuji

    2004-05-01

    Imaging of large objects at 17.7-keV low x-ray energy causes huge x-ray exposure to the objects even using interferometric phase-contrast x-ray CT (PCCT). Thus, we tried to obtain PCCT images at high x-ray energy of 35keV and examined the image quality using a formalin-fixed VX2 rabbit cancer specimen with 15-mm in diameter. The PCCT system consisted of an asymmetrically cut silicon (220) crystal, a monolithic x-ray interferometer, a phase-shifter, an object cell and an x-ray CCD camera. The PCCT at 35 keV clearly visualized various inner structures of VX2 rabbit cancer such as necrosis, cancer, the surrounding tumor vessels, and normal liver tissue. Besides, image-contrast was not degraded significantly. These results suggest that the PCCT at 35 KeV is sufficient to clearly depict the histopathological morphology of VX2 rabbit cancer specimen.

  12. High-speed and high-efficiency Si optical modulator with MOS junction, using solid-phase crystallization of polycrystalline silicon

    NASA Astrophysics Data System (ADS)

    Fujikata, Junichi; Takahashi, Masashi; Takahashi, Shigeki; Horikawa, Tsuyoshi; Nakamura, Takahiro

    2016-04-01

    We developed a high-speed and high-efficiency MOS-capacitor-type Si optical modulator (Si-MOD) by applying a low optical loss and a low resistivity of a polycrystalline silicon (poly-Si) gate with large grains. To achieve a low resistivity of a poly-Si film, a P-doped poly-Si film based on Si2H6 solid-phase crystallization (SPC) was developed, which showed a comparable resistivity to that of P-doped single-crystal Si. In addition, high-temperature annealing (HTA) after SPC was effective for realizing low optical loss. We designed the optimum Si-MOD structure and demonstrated a very high modulation efficiency of 0.3 V cm, which is very efficient among the Si-MODs developed thus far. High-speed (15 Gbps) operation was achieved with a small footprint of the 200-µm-long phase shifter and a low drive voltage of 1.5 Vpp at a low optical insertion loss of -2.2 dB and 1.55 µm wavelength.

  13. A chip scale optical Tx/Rx based on silicon photonics from views of multi-mode transmission

    NASA Astrophysics Data System (ADS)

    Ogura, Ichiro; Yashiki, Kenichiro; Suzuki, Yasuyuki; Hagihara, Yasuhiko; Nakamura, Takahiro; Kurata, Kazuhiko

    2016-03-01

    This paper focuses on latest progress in experimental and theoretical studies on silicon-based carrier-depletion PN-junction phase shifters in terms of high modulation efficiency for energy-efficient photonic networks of high transmission capacity. Modulation efficiency of rib-waveguide phase shifters having various PN-junction configuration are characterized with respect to DC figure of merit defined for phase shifters using carrier-plasma dispersion as the physical principle of refractive-index modulation. In addition, RF drive voltage required for 10-Gb/s on-off keying is characterized for rib-waveguide phase shifters including lateral and vertical PN-junction configurations.

  14. Ferrite microwave electronics Citations from the NTIS data base

    NASA Astrophysics Data System (ADS)

    Reed, W. E.

    1980-07-01

    Research reports on single crystals, thin films, dielectrics, semiconductor devices, integrated circuits, phase shifters, and waveguide components are cited. Studies on the microwave properties of ferrites are included.

  15. Study of Optical Phase Lock Loops and the Applications in Coherent Beam Combining and Coherence Cloning

    NASA Astrophysics Data System (ADS)

    Liang, Wei

    Optical Phase-Lock loops (OPLLs) have potential applications in phase coherent optics including frequency synthesis, clock distribution and recovery, jitter and noise reduction, etc. However, most implemented OPLLs are based on solid state lasers, fiber lasers, or specially designed semiconductor lasers, whose bulky size and high cost inhibit the applications of OPLLs. Semiconductor lasers have the advantages of low cost, small size, and high efficiency. In this thesis, I report on a study of OPLLs using commercial SCLs, and explore their novel applications in coherent beam combining and coherence cloning. In chapter 1-3, I will first introduce the theory of OPLLs and presents the experimental study of OPLLs made of different commercial SCLs. To improve the performance of OPLLs, electronic compensations using filter designs are also discussed and studied. In chapter 4-5, I will study the application of OPLLs in coherent beam combining. Using OPLLs, an array of slave lasers can be phase locked to the same master laser at the same frequency, their outputs can then be coherently combined. The phase variations of the element beams due to the optical path-length variations in fibers can be further corrected for by using multi-level OPLLs. This approach eliminates the use of the optical phase/frequency shifters conventionally required in a coherent beam combining system. In the proof of principle experiment, we have combined two lasers with a combining efficiency of 94% using the filled-aperture combining configuration. Furthermore, I will discuss the scalability of a cascaded filled-aperture combining system for the combination of a large number of lasers. OPLLs can also be used to reduce the phase noise of SCLs by locking them to a low noise master laser. In chapter 6, I will describe the theory of coherence cloning using OPLLs and present the experimental measurements of the linewidths and frequency noises of a low noise fiber laser, a free-running and locked slave

  16. Phase Coexistence in a Dynamic Phase Diagram.

    PubMed

    Gentile, Luigi; Coppola, Luigi; Balog, Sandor; Mortensen, Kell; Ranieri, Giuseppe A; Olsson, Ulf

    2015-08-01

    Metastability and phase coexistence are important concepts in colloidal science. Typically, the phase diagram of colloidal systems is considered at the equilibrium without the presence of an external field. However, several studies have reported phase transition under mechanical deformation. The reason behind phase coexistence under shear flow is not fully understood. Here, multilamellar vesicle (MLV)-to-sponge (L3 ) and MLV-to-Lα transitions upon increasing temperature are detected using flow small-angle neutron scattering techniques. Coexistence of Lα and MLV phases at 40 °C under shear flow is detected by using flow NMR spectroscopy. The unusual rheological behavior observed by studying the lamellar phase of a non-ionic surfactant is explained using (2) H NMR and diffusion flow NMR spectroscopy with the coexistence of planar lamellar-multilamellar vesicles. Moreover, a dynamic phase diagram over a wide range of temperatures is proposed.

  17. CrowdPhase: crowdsourcing the phase problem

    SciTech Connect

    Jorda, Julien; Sawaya, Michael R.; Yeates, Todd O.

    2014-06-01

    The idea of attacking the phase problem by crowdsourcing is introduced. Using an interactive, multi-player, web-based system, participants work simultaneously to select phase sets that correspond to better electron-density maps in order to solve low-resolution phasing problems. The human mind innately excels at some complex tasks that are difficult to solve using computers alone. For complex problems amenable to parallelization, strategies can be developed to exploit human intelligence in a collective form: such approaches are sometimes referred to as ‘crowdsourcing’. Here, a first attempt at a crowdsourced approach for low-resolution ab initio phasing in macromolecular crystallography is proposed. A collaborative online game named CrowdPhase was designed, which relies on a human-powered genetic algorithm, where players control the selection mechanism during the evolutionary process. The algorithm starts from a population of ‘individuals’, each with a random genetic makeup, in this case a map prepared from a random set of phases, and tries to cause the population to evolve towards individuals with better phases based on Darwinian survival of the fittest. Players apply their pattern-recognition capabilities to evaluate the electron-density maps generated from these sets of phases and to select the fittest individuals. A user-friendly interface, a training stage and a competitive scoring system foster a network of well trained players who can guide the genetic algorithm towards better solutions from generation to generation via gameplay. CrowdPhase was applied to two synthetic low-resolution phasing puzzles and it was shown that players could successfully obtain phase sets in the 30° phase error range and corresponding molecular envelopes showing agreement with the low-resolution models. The successful preliminary studies suggest that with further development the crowdsourcing approach could fill a gap in current crystallographic methods by making it

  18. Correction of contrast in projection systems by means of phase-controlled prism coatings and band-shifted twist compensators

    NASA Astrophysics Data System (ADS)

    Rosenbluth, Alan E.; Lu, Minhua; Yang, Kei H.; Ho, Kenneth; Singh, Rama N.; Nakasogi, Teruhiro

    2000-04-01

    Projectors that use LCOS lightvalves face special contrast requirements. Most configurations for reflective light valves employ tilted beam-dividing coatings that see both bright and dark polarization states. The optics must then be designed to eliminate polarization mixing at these coatings, which ordinarily arises when the S and P planes for different rays are non-parallel. We show how phase- controlled coatings can exploit the double-pass symmetry of the Plumbicon tri-prism geometry to correct this effect, reducing cross-polarized reflectivity to approximately 1E-3 when the light valve is mirror-like in black-state. Though contrast in different rays varies as a function of both ray skew component and coating angle of incidence, we show that for NA phase dispersion in their black-state, complicating contrast control in the optics. Scatter depolarization at the edges of pixel electrodes is enhanced in these light valves, because the inherent twist causes the backplane polarization to be rotated out of alignment with pixel edges. We show that all of these contrast degradation mechanisms can be addressed by incorporating into the light valve a compensating layer having opposite birefringence to the black-state TN active layer. Moreover, when the compensating layer and driven layer are blue-shifted to a shorter LC thickness than would ordinarily be appropriate for the wavelength band of interest, a highly achromatic response is obtained at all gray levels.

  19. Materials figure of merit for achromatic gradient index (GRIN) optics

    NASA Astrophysics Data System (ADS)

    Beadie, G.; Mait, J. N.; Flynn, R. A.; Milojkovic, P.

    2016-05-01

    A new figure of merit is developed for ranking pairs of materials as candidates for gradient index (GRIN) optics capable of good color correction. The approach leverages recent work which derives a connection in GRIN lenses between the optical properties of constituent materials and the wavelength dependence of the lens power. We extend the analysis here, the effectiveness of which is evidenced by a simulated f/3 GRIN lens with diffraction-limited performance over the visible spectrum, using the top material pair selected out of a database of >60,000 possible candidates.

  20. Further Exploration of Human Neonatal Chromatic-Achromatic Discrimination.

    ERIC Educational Resources Information Center

    Adams, Russell J.

    1995-01-01

    Newborns were habituated to white squares of varying size and luminance and retested with colored squares for recovery of habituation. Newborns could discriminate yellow-green from white in large squares, but not in small squares. They could not discriminate blue, blue-green, or purple from white. Results suggest newborns have little…

  1. Experimental realization of an achromatic magnetic mirror based on metamaterials.

    PubMed

    Pisano, Giampaolo; Ade, Peter A R; Tucker, Carole

    2016-06-20

    Our work relates to the use of metamaterials engineered to realize a metasurface approaching the exotic properties of an ideal object not observed in nature, a "magnetic mirror." Previous realizations were based on resonant structures that implied narrow bandwidths and large losses. The working principle of our device is ideally frequency-independent, it does not involve resonances and it does not rely on a specific technology. The performance of our prototype, working at millimeter wavelengths, has never been achieved before and it is superior to any other device reported in the literature, both in the microwave and optical regions. The device inherently has large bandwidth (144%), low losses (<1%), and is almost independent of incidence angle and polarization state, and thus approaches the behavior of an ideal magnetic mirror. Applications of magnetic mirrors range from low-profile antennas, absorbers to optoelectronic devices. Our device can be realized using different technologies to operate in other spectral regions. PMID:27409104

  2. Dispersive effects of transverse magnet displacements in rolled arc achromats

    SciTech Connect

    Fieguth, T.; Kheifets, S.; Murray, J.J.

    1986-09-22

    The effect of transverse displacements of combined function magnets is investigated where the disperion in not matched due to roll. This dispersion function is perturbed by displacement of combined function magnets either singly or coherently. In the latter case the effect of a systematic (or DC) offset of magnets is examined. This type of error can occur due to systematics in the placement or the readout of Beam Position Monitors or equivalently by correcting the orbit of a beam of the wrong momentum with respect to the Arc magnet excitation. 5 refs., 18 figs.

  3. CSR-induced emittance growth in achromats: Linear formalism revisited

    NASA Astrophysics Data System (ADS)

    Venturini, M.

    2015-09-01

    We review the R-matrix formalism used to describe Coherent Synchrotron Radiation (CSR)-induced projected emittance growth in electron beam transport lines and establish the connection with a description in terms of the dispersion-invariant function.

  4. Experimental realization of an achromatic magnetic mirror based on metamaterials.

    PubMed

    Pisano, Giampaolo; Ade, Peter A R; Tucker, Carole

    2016-06-20

    Our work relates to the use of metamaterials engineered to realize a metasurface approaching the exotic properties of an ideal object not observed in nature, a "magnetic mirror." Previous realizations were based on resonant structures that implied narrow bandwidths and large losses. The working principle of our device is ideally frequency-independent, it does not involve resonances and it does not rely on a specific technology. The performance of our prototype, working at millimeter wavelengths, has never been achieved before and it is superior to any other device reported in the literature, both in the microwave and optical regions. The device inherently has large bandwidth (144%), low losses (<1%), and is almost independent of incidence angle and polarization state, and thus approaches the behavior of an ideal magnetic mirror. Applications of magnetic mirrors range from low-profile antennas, absorbers to optoelectronic devices. Our device can be realized using different technologies to operate in other spectral regions.

  5. The Rainbow and the Achromatic Telescope: Two Case Studies.

    ERIC Educational Resources Information Center

    Rudd, M. Eugene

    1988-01-01

    Presented are two case studies on the perspective of the history of science. Provided are the contributions of 12 famous scientists with their historical illustrations and diagrams. Five conclusions are drawn from these studies. (YP)

  6. Diophantine Optics

    NASA Astrophysics Data System (ADS)

    Rouan, D.

    2016-09-01

    What I call Diophantine optics is the exploitation in optics of some remarkable algebraic relations between powers of integers. The name comes from Diophantus of Alexandria, a greek mathematician, known as the father of algebra. He studied polynomial equations with integer coefficients and integer solutions, called diophantine equations. Since constructive or destructive interferences are playing with optical path differences which are multiple integer (odd or even) of λ/2 and that the complex amplitude is a highly non-linear function of the optical path difference (or equivalently of the phase), one can understand that any Taylor development of this amplitude implies powers of integers. This is the link with Diophantine equations. We show how, especially in the field of interferometry, remarkable relations between powers of integers can help to solve several problems, such as achromatization of a phase shifter or deep nulling efficiency. It appears that all the research that was conducted in this frame of thinking, relates to the field of detection of exoplanets, a very active domain of astrophysics today.

  7. Quantitative optical phase microscopy.

    PubMed

    Barty, A; Nugent, K A; Paganin, D; Roberts, A

    1998-06-01

    We present a new method for the extraction of quantitative phase data from microscopic phase samples by use of partially coherent illumination and an ordinary transmission microscope. The technique produces quantitative images of the phase profile of the sample without phase unwrapping. The technique is able to recover phase even in the presence of amplitude modulation, making it significantly more powerful than existing methods of phase microscopy. We demonstrate the technique by providing quantitatively correct phase images of well-characterized test samples and show that the results obtained for more-complex samples correlate with structures observed with Nomarski differential interference contrast techniques.

  8. Cranial stereotactic radiosurgery: current status of the initial paradigm shifter.

    PubMed

    Sheehan, Jason P; Yen, Chun-Po; Lee, Cheng-Chia; Loeffler, Jay S

    2014-09-10

    The concept of stereotactic radiosurgery (SRS) was first described by Lars Leksell in 1951. It was proposed as a noninvasive alternative to open neurosurgical approaches to manage a variety of conditions. In the following decades, SRS emerged as a unique discipline involving a collegial partnership among neurosurgeons, radiation oncologists, and medical physicists. SRS relies on the precisely guided delivery of high-dose ionizing radiation to an intracranial target. The focused convergence of multiple beams yields a potent therapeutic effect on the target and a steep dose fall-off to surrounding structures, thereby minimizing the risk of collateral damage. SRS is typically administered in a single session but can be given in as many as five sessions or fractions. By providing an ablative effect noninvasively, SRS has altered the treatment paradigms for benign and malignant intracranial tumors, functional disorders, and vascular malformations. Literature on extensive intracranial radiosurgery has unequivocally demonstrated the favorable benefit-to-risk profile that SRS affords for appropriately selected patients. In a departure from conventional radiotherapeutic strategies, radiosurgical principles have recently been extended to extracranial indications such as lung, spine, and liver tumors. The paradigm shift resulting from radiosurgery continues to alter the landscape of related fields. PMID:25113762

  9. Gas scintillation drift chambers with wave shifter fiber readout

    NASA Technical Reports Server (NTRS)

    Sadoulet, Bernard; Weiss, Steven; Parsons, Ann; Lin, Robert P.; Smith, Garth

    1988-01-01

    Results for a prototype xenon gas scintillation drift chamber are presented. Its operation is discussed using two types of light detection schemes: one based on an Anger camera geometry and one based on an array of wave-shifting light fibers. The results are judged to demonstrate the instrument's potential.

  10. Cranial Stereotactic Radiosurgery: Current Status of the Initial Paradigm Shifter

    PubMed Central

    Sheehan, Jason P.; Yen, Chun-Po; Lee, Cheng-Chia; Loeffler, Jay S.

    2014-01-01

    The concept of stereotactic radiosurgery (SRS) was first described by Lars Leksell in 1951. It was proposed as a noninvasive alternative to open neurosurgical approaches to manage a variety of conditions. In the following decades, SRS emerged as a unique discipline involving a collegial partnership among neurosurgeons, radiation oncologists, and medical physicists. SRS relies on the precisely guided delivery of high-dose ionizing radiation to an intracranial target. The focused convergence of multiple beams yields a potent therapeutic effect on the target and a steep dose fall-off to surrounding structures, thereby minimizing the risk of collateral damage. SRS is typically administered in a single session but can be given in as many as five sessions or fractions. By providing an ablative effect noninvasively, SRS has altered the treatment paradigms for benign and malignant intracranial tumors, functional disorders, and vascular malformations. Literature on extensive intracranial radiosurgery has unequivocally demonstrated the favorable benefit-to-risk profile that SRS affords for appropriately selected patients. In a departure from conventional radiotherapeutic strategies, radiosurgical principles have recently been extended to extracranial indications such as lung, spine, and liver tumors. The paradigm shift resulting from radiosurgery continues to alter the landscape of related fields. PMID:25113762

  11. Laser-induced damage thresholds of starched PMMA waveplates

    NASA Astrophysics Data System (ADS)

    Melninkaitis, A.; Mikšys, D.; Maciulevičius, M.; Sirutkaitis, V.; Šlekys, G.; Samoylov, A. V.

    2007-01-01

    Polymethyl methacrylate (PMMA) is a versatile polymeric material that is well suited for fabrication of many commercial optical components: lenses, fibers, windows, phase waveplates and others. Our focus is achromatic zero-order waveplates made of anisotropic PMMA which can be used to modify the state of polarization of electromagnetic radiation. Such waveplates have a broad range of application in devices where polarized radiation is used. For example, when tunable lasers are used or when spectropolarimetric measurements are performed, one needs an achromatic waveplate providing a specific retardation in a wide wavelength range. Herewith anisotropic properties of PMMA subjected to one-axis stretching are analyzed and the technology for manufacturing such achromatic and super-achromatic, one-axis-stretched PMMA waveplates is described. This technology excludes any mechanical processing of waveplate component surfaces. Technical characteristics of achromatic and super-achromatic waveplates manufactured of PMMA including results of laser-induced damage threshold (LIDT) measurements are discussed below.

  12. CrowdPhase: crowdsourcing the phase problem.

    PubMed

    Jorda, Julien; Sawaya, Michael R; Yeates, Todd O

    2014-06-01

    The human mind innately excels at some complex tasks that are difficult to solve using computers alone. For complex problems amenable to parallelization, strategies can be developed to exploit human intelligence in a collective form: such approaches are sometimes referred to as `crowdsourcing'. Here, a first attempt at a crowdsourced approach for low-resolution ab initio phasing in macromolecular crystallography is proposed. A collaborative online game named CrowdPhase was designed, which relies on a human-powered genetic algorithm, where players control the selection mechanism during the evolutionary process. The algorithm starts from a population of `individuals', each with a random genetic makeup, in this case a map prepared from a random set of phases, and tries to cause the population to evolve towards individuals with better phases based on Darwinian survival of the fittest. Players apply their pattern-recognition capabilities to evaluate the electron-density maps generated from these sets of phases and to select the fittest individuals. A user-friendly interface, a training stage and a competitive scoring system foster a network of well trained players who can guide the genetic algorithm towards better solutions from generation to generation via gameplay. CrowdPhase was applied to two synthetic low-resolution phasing puzzles and it was shown that players could successfully obtain phase sets in the 30° phase error range and corresponding molecular envelopes showing agreement with the low-resolution models. The successful preliminary studies suggest that with further development the crowdsourcing approach could fill a gap in current crystallographic methods by making it possible to extract meaningful information in cases where limited resolution might otherwise prevent initial phasing. PMID:24914965

  13. Engineering holographic phase diagrams

    NASA Astrophysics Data System (ADS)

    Chen, Jiunn-Wei; Dai, Shou-Huang; Maity, Debaprasad; Zhang, Yun-Long

    2016-10-01

    By introducing interacting scalar fields, we tried to engineer physically motivated holographic phase diagrams which may be interesting in the context of various known condensed matter systems. We introduce an additional scalar field in the bulk which provides a tunable parameter in the boundary theory. By exploiting the way the tuning parameter changes the effective masses of the bulk interacting scalar fields, desired phase diagrams can be engineered for the boundary order parameters dual to those scalar fields. We give a few examples of generating phase diagrams with phase boundaries which are strikingly similar to the known quantum phases at low temperature such as the superconducting phases. However, the important difference is that all the phases we have discussed are characterized by neutral order parameters. At the end, we discuss if there exists any emerging scaling symmetry associated with a quantum critical point hidden under the dome in this phase diagram.

  14. Digital quadrature phase detection

    DOEpatents

    Smith, J.A.; Johnson, J.A.

    1992-05-26

    A system for detecting the phase of a frequency or phase modulated signal that includes digital quadrature sampling of the frequency or phase modulated signal at two times that are one quarter of a cycle of a reference signal apart, determination of the arctangent of the ratio of a first sampling of the frequency or phase modulated signal to the second sampling of the frequency or phase modulated signal, and a determination of quadrant in which the phase determination is increased by 2[pi] when the quadrant changes from the first quadrant to the fourth quadrant and decreased by 2[pi] when the quadrant changes from the fourth quadrant to the first quadrant whereby the absolute phase of the frequency or phase modulated signal can be determined using an arbitrary reference convention. 6 figs.

  15. Digital quadrature phase detection

    DOEpatents

    Smith, James A.; Johnson, John A.

    1992-01-01

    A system for detecting the phase of a frequency of phase modulated signal that includes digital quadrature sampling of the frequency or phase modulated signal at two times that are one quarter of a cycle of a reference signal apart, determination of the arctangent of the ratio of a first sampling of the frequency or phase modulated signal to the second sampling of the frequency or phase modulated signal, and a determination of quadrant in which the phase determination is increased by 2.pi. when the quadrant changes from the first quadrant to the fourth quadrant and decreased by 2.pi. when the quadrant changes from the fourth quadrant to the first quadrant whereby the absolute phase of the frequency or phase modulated signal can be determined using an arbitrary reference convention.

  16. Fully Printed, Flexible, Phased Array Antenna for Lunar Surface Communication

    NASA Technical Reports Server (NTRS)

    Subbaraman, Harish; Hen, Ray T.; Lu, Xuejun; Chen, Maggie Yihong

    2013-01-01

    NASAs future exploration missions focus on the manned exploration of the Moon, Mars, and beyond, which will rely heavily on the development of a reliable communications infrastructure from planetary surface-to-surface, surface-to-orbit, and back to Earth. Flexible antennas are highly desired in many scenarios. Active phased array antennas (active PAAs) with distributed control and processing electronics at the surface of an antenna aperture offer numerous advantages for radar communications. Large-area active PAAs on flexible substrates are of particular interest in NASA s space radars due to their efficient inflatable package that can be rolled up during transportation and deployed in space. Such an inflatable package significantly reduces stowage volume and mass. Because of these performance and packaging advantages, large-area inflatable active PAAs are highly desired in NASA s surface-to-orbit and surface-to-relay communications. To address the issues of flexible electronics, a room-temperature printing process of active phased-array antennas on a flexible Kapton substrate was developed. Field effect transistors (FETs) based on carbon nanotubes (CNTs), with many unique physical properties, were successfully proved feasible for the PAA system. This innovation is a new type of fully inkjet-printable, two-dimensional, high-frequency PAA on a flexible substrate at room temperature. The designed electronic circuit components, such as the FET switches in the phase shifter, metal interconnection lines, microstrip transmission lines, etc., are all printed using a special inkjet printer. Using the developed technology, entire 1x4, 2x2, and 4x4 PAA systems were developed, packaged, and demonstrated at 5.3 GHz. Several key solutions are addressed in this work to solve the fabrication issues. The source/drain contact is developed using droplets of silver ink printed on the source/drain areas prior to applying CNT thin-film. The wet silver ink droplets allow the silver to

  17. Phase from chromatic aberrations.

    PubMed

    Waller, Laura; Kou, Shan Shan; Sheppard, Colin J R; Barbastathis, George

    2010-10-25

    We show that phase objects may be computed accurately from a single color image in a brightfield microscope, with no hardware modification. Our technique uses the chromatic aberration that is inherent to every lens-based imaging system as a phase contrast mechanism. This leads to a simple and inexpensive way of achieving single-shot quantitative phase recovery by a modified Transport of Intensity Equation (TIE) solution, allowing real-time phase imaging in a traditional microscope. PMID:21164620

  18. Phase jitter in a differential phase experiment.

    NASA Technical Reports Server (NTRS)

    Tanenbaum, B. S.; Connolly, D. J.; Austin, G. L.

    1973-01-01

    Austin (1971) had concluded that, because of the 'phase jitter,' the differential phase experiment is useful over a more limited height range than the differential absorption experiment. Several observations are presented to show that this conclusion is premature. It is pointed out that the logical basis of the differential absorption experiment also requires that the O- and X-mode echoes, at a given time, come from the same irregularities. Austin's calculations are believed to contain a systematic error above 80 km.

  19. Perceptions about Moon Phases.

    ERIC Educational Resources Information Center

    Rider, Steven

    2002-01-01

    Presents research on different techniques to determine the level of understanding among middle school students regarding the phases of the moon. Quotes student responses to provide some insight into students' level of understanding of general knowledge about the moon, moon phases, and modeling the phases. Presents implications for teachers. (KHR)

  20. Phase Equilibria, Phase Diagrams and Phase Transformations - 2nd Edition

    NASA Astrophysics Data System (ADS)

    Hillert, Mats

    2006-03-01

    Computational tools allow material scientists to model and analyze increasingly complicated systems to appreciate material behavior. Accurate use and interpretation however, requires a strong understanding of the thermodynamic principles that underpin phase equilibrium, transformation and state. This fully revised and updated edition covers the fundamentals of thermodynamics, with a view to modern computer applications. The theoretical basis of chemical equilibria and chemical changes is covered with an emphasis on the properties of phase diagrams. Starting with the basic principles, discussion moves to systems involving multiple phases. New chapters cover irreversible thermodynamics, extremum principles, and the thermodynamics of surfaces and interfaces. Theoretical descriptions of equilibrium conditions, the state of systems at equilibrium and the changes as equilibrium is reached, are all demonstrated graphically. With illustrative examples - many computer calculated - and worked examples, this textbook is an valuable resource for advanced undergraduates and graduate students in materials science and engineering. Fully revised and updated edition covering the fundamentals of thermodynamics with a view to modern computer applications such as Thermo-Calc Emphasis is placed on phase diagrams, the key application of thermodynamics Contains numerous illustrative examples, many computer-calculated and some for real systems, and worked examples to help demonstrate the principles

  1. High Contrast Vacuum Nuller Testbed (VNT) Contrast, Performance and Null Control

    NASA Technical Reports Server (NTRS)

    Lyon, Richard G.; Clampin, Mark; Petrone, Peter; Mallik, Udayan; Madison, Timothy; Bolcar, Matthew R.

    2012-01-01

    Herein we report on our contrast assessment and the development, sensing and control of the Vacuum Nuller Testbed to realize a Visible Nulling Coronagraphy (VNC) for exoplanet detection and characterization. Tbe VNC is one of the few approaches that works with filled, segmented and sparse or diluted-aperture telescope systems. It thus spans a range of potential future NASA telescopes and could be flown as a separate instrument on such a future mission. NASA/Goddard Space Flight Center has an established effort to develop VNC technologies, and an incremental sequence of testbeds to advance this approach and its critical technologies. We discuss the development of the vacuum Visible Nulling Coronagraph testbed (VNT). The VNT is an ultra-stable vibration isolated testbed that operates under closed-loop control within a vacuum chamber. It will be used to achieve an incremental sequence of three visible-light nulling milestones with sequentially higher contrasts of 10(exp 8), 10(exp 9) and ideally 10(exp 10) at an inner working angle of 2*lambda/D. The VNT is based on a modified Mach-Zehnder nulling interferometer, with a "W" configuration to accommodate a hex-packed MEMS based deformable mirror, a coherent fiber bundle and achromatic phase shifters. We discuss the laboratory results, optical configuration, critical technologies and the null sensing and control approach.

  2. Vacuum Nuller Testbed (VNT) Performance, Characterization and Null Control: Progress Report

    NASA Technical Reports Server (NTRS)

    Lyon, Richard G.; Clampin, Mark; Petrone, Peter; Mallik, Udayan; Madison, Timothy; Bolcar, Matthew R.; Noecker, M. Charley; Kendrick, Stephen; Helmbrecht, Michael

    2011-01-01

    Herein we report on the development. sensing and control and our first results with the Vacuum Nuller Testbed to realize a Visible Nulling Coronagraph (VNC) for exoplanet coronagraphy. The VNC is one of the few approaches that works with filled. segmented and sparse or diluted-aperture telescope systems. It thus spans a range of potential future NASA telescopes and could be Hown as a separate instrument on such a future mission. NASA/Goddard Space Flight Center (GSFC) has a well-established effort to develop VNC technologies. and has developed an incremental sequence of VNC testbeds to advance this approach and the enabling technologies associated with it. We discuss the continued development of the vacuum Visible Nulling Coronagraph testbed (VNT). Tbe VNT is an ultra-stable vibration isolated testbed that operates under closed-loop control within a vacuum chamber. It will be used to achieve an incremental sequence of three visible-light nulling milestones with sequentially higher contrasts of 10(sup 8), 10(sup 9) and ideally 10(sup 10) at an inner working angle of 2*lambda/D. The VNT is based on a modified Mach-Zehnder nulling interferometer, with a "W" configuration to accommodate a hex-packed MEMS based deformable mirror, a coherent fiber bundle and achromatic phase shifters. We discuss the initial laboratory results, the optical configuration, critical technologies and the null sensing and control approach.

  3. Visible Nulling Coronagraphy Testbed Development for Exoplanet Detection

    NASA Technical Reports Server (NTRS)

    Lyon, Richard G.; Clampin, Mark; Woodruff, Robert A.; Vasudevan, Gopal; Thompson, Patrick; Chen, Andrew; Petrone, Peter; Booth, Andrew; Madison, Timothy; Bolcar, Matthew; Noecker, M. Charley; Kendrick, Stephen; Melnick, Gary; Tolls, Volker

    2010-01-01

    Three of the recently completed NASA Astrophysics Strategic Mission Concept (ASMC) studies addressed the feasibility of using a Visible Nulling Coronagraph (VNC) as the prime instrument for exoplanet science. The VNC approach is one of the few approaches that works with filled, segmented and sparse or diluted aperture telescope systems and thus spans the space of potential ASMC exoplanet missions. NASA/Goddard Space Flight Center (GSFC) has a well-established effort to develop VNC technologies and has developed an incremental sequence of VNC testbeds to advance the this approach and the technologies associated with it. Herein we report on the continued development of the vacuum Visible Nulling Coronagraph testbed (VNT). The VNT is an ultra-stable vibration isolated testbed that operates under high bandwidth closed-loop control within a vacuum chamber. It will be used to achieve an incremental sequence of three visible light nulling milestones of sequentially higher contrasts of 10(exp 8) , 10(exp 9) and 10(exp 10) at an inner working angle of 2*lambda/D and ultimately culminate in spectrally broadband (>20%) high contrast imaging. Each of the milestones, one per year, is traceable to one or more of the ASMC studies. The VNT uses a modified Mach-Zehnder nulling interferometer, modified with a modified "W" configuration to accommodate a hex-packed MEMS based deformable mirror, a coherent fiber bundle and achromatic phase shifters. Discussed will be the optical configuration laboratory results, critical technologies and the null sensing and control approach.

  4. High Contrast Vacuum Nuller Testbed (VNT) Contrast, Performance and Null Control

    NASA Technical Reports Server (NTRS)

    Lyon, Richard G.; Clampin, Mark; Petrone, Peter; Mallik, Udayan; Madison, Timothy; Bolcar, Matthew R.

    2012-01-01

    Herein we report on our Visible Nulling Coronagraph high-contrast result of 109 contrast averaged over a focal planeregion extending from 14 D with the Vacuum Nuller Testbed (VNT) in a vibration isolated vacuum chamber. TheVNC is a hybrid interferometriccoronagraphic approach for exoplanet science. It operates with high Lyot stopefficiency for filled, segmented and sparse or diluted-aperture telescopes, thereby spanning the range of potential futureNASA flight telescopes. NASAGoddard Space Flight Center (GSFC) has a well-established effort to develop the VNCand its technologies, and has developed an incremental sequence of VNC testbeds to advance this approach and itsenabling technologies. These testbeds have enabled advancement of high-contrast, visible light, nulling interferometry tounprecedented levels. The VNC is based on a modified Mach-Zehnder nulling interferometer, with a W configurationto accommodate a hex-packed MEMS based deformable mirror, a coherent fiber bundle and achromatic phase shifters.We give an overview of the VNT and discuss the high-contrast laboratory results, the optical configuration, criticaltechnologies and null sensing and control.

  5. Phase microscope imaging in phase space

    NASA Astrophysics Data System (ADS)

    Sheppard, Colin J. R.; Mehta, Shalin B.

    2016-03-01

    Imaging in a bright field or phase contrast microscope is partially coherent. We have found that the image can be conveniently considered and modeled in terms of the Wigner distribution function (WDF) of the object transmission. The WDF of the object has a simple physical interpretation for the case of a slowly varying object. Basically, the image intensity is the spatial marginal of the spatial convolution of the object WDF with the phase space imager kernel (PSIkernel), a rotated version of the transmission cross-coefficient. The PSI-kernel can be regarded as a partially-coherent generalization of the point spread function. This approach can be extended to consider the partial coherence of the image itself. In particular, we can consider the mutual intensity, WDF or ambiguity function of the image. It is important to note that the spatial convolution of the object WDF with the PSI-kernel is not a WDF, and not the WDF of the image. The phase space representations of the image have relevance to phase reconstruction methods such as phase space tomography, or the transport of intensity equation approach, and to the three-dimensional image properties.

  6. Frequency stabilization in nonlinear MEMS and NEMS oscillators

    DOEpatents

    Lopez, Omar Daniel; Antonio, Dario

    2014-09-16

    An illustrative system includes an amplifier operably connected to a phase shifter. The amplifier is configured to amplify a voltage from an oscillator. The phase shifter is operably connected to a driving amplitude control, wherein the phase shifter is configured to phase shift the amplified voltage and is configured to set an amplitude of the phase shifted voltage. The oscillator is operably connected to the driving amplitude control. The phase shifted voltage drives the oscillator. The oscillator is at an internal resonance condition, based at least on the amplitude of the phase shifted voltage, that stabilizes frequency oscillations in the oscillator.

  7. Gymnastics in Phase Space

    SciTech Connect

    Chao, Alexander Wu; /SLAC

    2012-03-01

    As accelerator technology advances, the requirements on accelerator beam quality become increasingly demanding. Facing these new demands, the topic of phase space gymnastics is becoming a new focus of accelerator physics R&D. In a phase space gymnastics, the beam's phase space distribution is manipulated and precision tailored to meet the required beam qualities. On the other hand, all realization of such gymnastics will have to obey accelerator physics principles as well as technological limitations. Recent examples of phase space gymnastics include Emittance exchanges, Phase space exchanges, Emittance partitioning, Seeded FELs and Microbunched beams. The emittance related topics of this list are reviewed in this report. The accelerator physics basis, the optics design principles that provide these phase space manipulations, and the possible applications of these gymnastics, are discussed. This fascinating new field promises to be a powerful tool of the future.

  8. PHASE DIFFERENTIAL INDICATING CIRCUIT

    DOEpatents

    Kirsten, F.A.

    1962-01-01

    An electronic circuit for totalizing the net phase difference between two alternating current signals is designed which responds to both increasing and decreasing phase changes. A phase comparator provldes an output pulse for each 360 deg of phase difference occurring, there being a negative pulse for phase shtft in one direction and a positive pulse for a phase shift in the opposite direction. A counting circuit utilizing glow discharge tubes receives the negative and positive pulses at a single input terminal and provides a running net total, pulses of one polarity dded and pulses of the opposite polarity being subtracted. The glow discharge tubes may be decaded to increase the total count capacity. (AEC)

  9. Phase Holograms In PMMA

    NASA Technical Reports Server (NTRS)

    Maker, Paul D.; Muller, Richard E.

    1994-01-01

    Complex, computer-generated phase holograms written in thin films of poly(methyl methacrylate) (PMMA) by process of electron-beam exposure followed by chemical development. Spatial variations of phase delay in holograms quasi-continuous, as distinquished from stepwise as in binary phase holograms made by integrated-circuit fabrication. Holograms more precise than binary holograms. Greater continuity and precision results in decreased scattering loss and increased imaging efficiency.

  10. Crystal phase identification

    DOEpatents

    Michael, Joseph R.; Goehner, Raymond P.; Schlienger, Max E.

    2001-01-01

    A method and apparatus for determining the crystalline phase and crystalline characteristics of a sample. This invention provides a method and apparatus for unambiguously identifying and determining the crystalline phase and crystalline characteristics of a sample by using an electron beam generator, such as a scanning electron microscope, to obtain a backscattered electron Kikuchi pattern of a sample, and extracting crystallographic and composition data that is matched to database information to provide a quick and automatic method to identify crystalline phases.

  11. Cosmological phase transitions

    SciTech Connect

    Kolb, E.W. |

    1993-10-01

    If modern ideas about the role of spontaneous symmetry breaking in fundamental physics are correct, then the Universe should have undergone a series of phase transitions early in its history. The study of cosmological phase transitions has become an important aspect of early-Universe cosmology. In this lecture I review some very recent work on three aspects of phase transitions: the electroweak transition, texture, and axions.

  12. Phase detection of chaos.

    PubMed

    Follmann, Rosangela; Macau, Elbert E N; Rosa, Epaminondas

    2011-01-01

    A technique, first introduced in the context of pseudoperiodic sound waves, is here applied to the problem of detecting the phase of phase coherent and also phase noncoherent chaotic oscillators. The approach is based on finding sinusoidal fits to segments of the signal, therefore obtaining, for each segment, an appropriate frequency from which a phase can be derived. Central to the method is a judicious choice for the size of a sliding window and for the frequency range, as well as for the window advancing step. The approach is robust against moderate noise levels and three cases are presented for demonstrating the applicability of the method. PMID:21405762

  13. Phase Equilibria Diagrams Database

    National Institute of Standards and Technology Data Gateway

    SRD 31 NIST/ACerS Phase Equilibria Diagrams Database (PC database for purchase)   The Phase Equilibria Diagrams Database contains commentaries and more than 21,000 diagrams for non-organic systems, including those published in all 21 hard-copy volumes produced as part of the ACerS-NIST Phase Equilibria Diagrams Program (formerly titled Phase Diagrams for Ceramists): Volumes I through XIV (blue books); Annuals 91, 92, 93; High Tc Superconductors I & II; Zirconium & Zirconia Systems; and Electronic Ceramics I. Materials covered include oxides as well as non-oxide systems such as chalcogenides and pnictides, phosphates, salt systems, and mixed systems of these classes.

  14. Phase Contrast Imaging

    SciTech Connect

    Menk, Ralf Hendrik

    2008-11-13

    All standard (medical) x-ray imaging technologies, rely primarily on the amplitude properties of the incident radiation, and do not depend on its phase. This is unchanged since the discovery by Roentgen that the intensity of an x-ray beam, as measured by the exposure on a film, was related to the relative transmission properties of an object. However, recently various imaging techniques have emerged which depend on the phase of the x-rays as well as the amplitude. Phase becomes important when the beam is coherent and the imaging system is sensitive to interference phenomena. Significant new advances have been made in coherent optic theory and techniques, which now promise phase information in medical imaging. The development of perfect crystal optics and the increasing availability of synchrotron radiation facilities have contributed to a significant increase in the application of phase based imaging in materials and life sciences. Unique source characteristics such as high intensity, monochromaticity, coherence and high collimating provide an ideal source for advanced imaging. Phase contrast imaging has been applied in both projection and computed tomography modes, and recent applications have been made in the field of medical imaging. Due to the underlying principle of X-ray detection conventional image receptors register only intensities of wave fields and not their phases. During the last decade basically five different methods were developed that translate the phase information into intensity variations. These methods are based on measuring the phase shift {phi} directly (using interference phenomena), the gradient {nabla}{sub {phi}}, or the Laplacian {nabla}{sup 2}{phi}. All three methods can be applied to polychromatic X-ray sources keeping in mind that the native source is synchrotron radiation, featuring monochromatic and reasonable coherent X-ray beams. Due to the vast difference in the coefficients that are driven absorption and phase effects (factor 1

  15. Demonstrating Phase Changes.

    ERIC Educational Resources Information Center

    Rohr, Walter

    1995-01-01

    Presents two experiments that demonstrate phase changes. The first experiment explores phase changes of carbon dioxide using powdered dry ice sealed in a piece of clear plastic tubing. The second experiment demonstrates an equilibrium process in which a crystal grows in equilibrium with its saturated solution. (PVD)

  16. A Phase Odyssey

    SciTech Connect

    Nugent, K.A.; Paganin, D.; Gureyev, T.E.

    2009-01-06

    We are introduced to the effects of phase from the earliest days of our childhood, from the nursery rhyme above (or its less verbose for 'Twinkle, Twinkle Little Star') to the shimmer over a hot road and the network of bright lines at the bottom of a swimming pool. These are all manifestations of phase. And there are many more.

  17. Lunar Phases Planisphere

    ERIC Educational Resources Information Center

    Shawl, Stephen J.

    2010-01-01

    This paper describes a lunar phases planisphere with which a user can answer questions about the rising and setting times of the Moon as well as questions about where the Moon will be at a given phase and time. The article contains figures that can be photocopied to make the planisphere. (Contains 2 figures.)

  18. Simulation of phase structures

    SciTech Connect

    Lawson, J.

    1995-04-20

    This memo outlines a procedure developed by the author to extract information from phase measurements and produce a simulated phase structure for use in modeling optical systems, including characteristic optics for the Beamlet and NIF laser systems. The report includes an IDL program listing.

  19. Sampler bias -- Phase 1

    SciTech Connect

    Blanchard, R.J.

    1995-03-07

    This documents Phase 1 determinations on sampler induced bias for four sampler types used in tank characterization. Each sampler, grab sampler or bottle-on-a-string, auger sampler, sludge sampler and universal sampler, is briefly discussed and their physical limits noted. Phase 2 of this document will define additional testing and analysis to further define Sampler Bias.

  20. LIGHT NONAQUEOUS PHASE LIQUIDS

    EPA Science Inventory

    Nonaqueous phase liquids (NAPLS) are hydrocarbons that exist as a separate, immiscible phase when in contact with water and/or air. ifferences in the physical and chemical properties of water and NAPL result in the formation of a physical interface between the liquids which preve...

  1. Optimizing qubit phase estimation

    NASA Astrophysics Data System (ADS)

    Chapeau-Blondeau, François

    2016-08-01

    The theory of quantum state estimation is exploited here to investigate the most efficient strategies for this task, especially targeting a complete picture identifying optimal conditions in terms of Fisher information, quantum measurement, and associated estimator. The approach is specified to estimation of the phase of a qubit in a rotation around an arbitrary given axis, equivalent to estimating the phase of an arbitrary single-qubit quantum gate, both in noise-free and then in noisy conditions. In noise-free conditions, we establish the possibility of defining an optimal quantum probe, optimal quantum measurement, and optimal estimator together capable of achieving the ultimate best performance uniformly for any unknown phase. With arbitrary quantum noise, we show that in general the optimal solutions are phase dependent and require adaptive techniques for practical implementation. However, for the important case of the depolarizing noise, we again establish the possibility of a quantum probe, quantum measurement, and estimator uniformly optimal for any unknown phase. In this way, for qubit phase estimation, without and then with quantum noise, we characterize the phase-independent optimal solutions when they generally exist, and also identify the complementary conditions where the optimal solutions are phase dependent and only adaptively implementable.

  2. UPVG phase 2 report

    SciTech Connect

    1995-08-01

    The Utility PhotoVoltaic Group (UPVG), supported by member dues and a grant from the US Department of Energy, has as its mission the acceleration of the use of cost-effective small-scale and emerging large-scale applications of photovoltaics for the benefit of electric utilities and their customers. Formed in October, 1992, with the support of the American Public Power Association, Edison Electric Institute, and the National Rural Electric Cooperative Association, the UPVG currently has 90 members from all sectors of the electric utility industry. The UPVG`s efforts as conceived were divided into four phases: Phase 0--program plan; Phase 1--organization and strategy development; Phase 2--creating market assurance; and Phase 3--higher volume purchases. The Phase 0 effort developed the program plan and was completed early in 1993. The Phase 1 goal was to develop the necessary background information and analysis to lead to a decision as to which strategies could be undertaken by utilities to promote greater understanding of PV markets and achieve increased volumes of PV purchases. This report provides the details of the UPVG`s Phase 2 efforts to initiate TEAM-UP, its multiyear, 50-MW hardware initiative.

  3. Magnetic lyotropic phases

    NASA Astrophysics Data System (ADS)

    Dabadie, J. C.; Fabre, P.; Veyssie, M.; Cabuil, V.; Massart, R.

    1990-12-01

    The authors have demonstrated that it is possible to include tiny magnetic particles into different types of lyotropic phases, such as sponge, microemulsion or lamellar phases. The first point of interest in these results is to prove the compatibility between solid colloids and organized liquids. As for the hybrid lamellar phase, they have studied its phase diagram versus the smectic period and the particle concentration-which are the two relevant parameters-and deduced its range of stability. Moreover, this ferrosmectic phase exhibits original features when subjected to a magnetic field even when it is very low: the lamellae orientate in the direction of the field. The detailed mechanism of this strong coupling between the spherical particles, the flexible membranes and the magnetic field is not fully understood, and deserves further experimental and theoretical study.

  4. Spectral Domain Phase Microscopy

    NASA Astrophysics Data System (ADS)

    Hendargo, Hansford C.; Ellerbee, Audrey K.; Izatt, Joseph A.

    Spectral domain phase microscopy (SDPM) is a functional extension of optical coherence tomography (OCT) using common-path interferometry to produce phase-referenced images of dynamic samples. Like OCT, axial resolution in SDPM is determined by the source coherence length, while lateral resolution is limited by diffraction in the microscope optics. However, the quantitative phase information SDPM generates is sensitive to nanometer-scale displacements of scattering structures. The use of a common-path optical geometry yields an imaging system with high phase stability. Due to coherence gating, SDPM can achieve full depth discrimination, allowing for independent motion resolution of subcellular structures throughout the sample volume. Here we review the basic theory of OCT and SDPM along with applications of SDPM in cellular imaging to measure topology, Doppler flow in single-celled organisms, time-resolved motions, rheological information of the cytoskeleton, and optical signaling of neural activation. Phase imaging limitations, artifacts, and sensitivity considerations are discussed.

  5. Gas Phase Nanoparticle Synthesis

    NASA Astrophysics Data System (ADS)

    Granqvist, Claes; Kish, Laszlo; Marlow, William

    This book deals with gas-phase nanoparticle synthesis and is intended for researchers and research students in nanomaterials science and engineering, condensed matter physics and chemistry, and aerosol science. Gas-phase nanoparticle synthesis is instrumental to nanotechnology - a field in current focus that raises hopes for environmentally benign, resource-lean manufacturing. Nanoparticles can be produced by many physical, chemical, and even biological routes. Gas-phase synthesis is particularly interesting since one can achieve accurate manufacturing control and hence industrial viability.

  6. Geometry and Moon Phases.

    ERIC Educational Resources Information Center

    Thompson, Kenneth W.; Harrell, Marvin E.

    1997-01-01

    Describes an activity, designed to comply with the National Science Education Standards, that integrates science and mathematics concepts. Mathematical modeling of the moon's phases is employed to show students the role of mathematics in describing scientific phenomena. (DKM)

  7. The Next Phase.

    ERIC Educational Resources Information Center

    Oualline, John; Rabenaldt, Carl

    2002-01-01

    Discusses how phased facility assessments, rather than one comprehensive assessment, may be an answer to identifying and addressing capital renewal and deferred maintenance. Presents a table outlining the facility assessment levels and attendant measurement methods. (EV)

  8. ELECTRONIC PHASE CONTROL CIRCUIT

    DOEpatents

    Salisbury, J.D.; Klein, W.W.; Hansen, C.F.

    1959-04-21

    An electronic circuit is described for controlling the phase of radio frequency energy applied to a multicavity linear accelerator. In one application of the circuit two cavities are excited from a single radio frequency source, with one cavity directly coupled to the source and the other cavity coupled through a delay line of special construction. A phase detector provides a bipolar d-c output signal proportional to the difference in phase between the voltage in the two cavities. This d-c signal controls a bias supply which provides a d-c output for varying the capacitnce of voltage sensitive capacitors in the delay line. The over-all operation of the circuit is completely electronic, overcoming the time response limitations of the electromechanical control systems, and the relative phase relationship of the radio frequency voltages in the two caviiies is continuously controlled to effect particle acceleration.

  9. Digital Receiver Phase Meter

    NASA Technical Reports Server (NTRS)

    Marcin, Martin; Abramovici, Alexander

    2008-01-01

    The software of a commercially available digital radio receiver has been modified to make the receiver function as a two-channel low-noise phase meter. This phase meter is a prototype in the continuing development of a phase meter for a system in which radiofrequency (RF) signals in the two channels would be outputs of a spaceborne heterodyne laser interferometer for detecting gravitational waves. The frequencies of the signals could include a common Doppler-shift component of as much as 15 MHz. The phase meter is required to measure the relative phases of the signals in the two channels at a sampling rate of 10 Hz at a root power spectral density <5 microcycle/(Hz)1/2 and to be capable of determining the power spectral density of the phase difference over the frequency range from 1 mHz to 1 Hz. Such a phase meter could also be used on Earth to perform similar measurements in laser metrology of moving bodies. To illustrate part of the principle of operation of the phase meter, the figure includes a simplified block diagram of a basic singlechannel digital receiver. The input RF signal is first fed to the input terminal of an analog-to-digital converter (ADC). To prevent aliasing errors in the ADC, the sampling rate must be at least twice the input signal frequency. The sampling rate of the ADC is governed by a sampling clock, which also drives a digital local oscillator (DLO), which is a direct digital frequency synthesizer. The DLO produces samples of sine and cosine signals at a programmed tuning frequency. The sine and cosine samples are mixed with (that is, multiplied by) the samples from the ADC, then low-pass filtered to obtain in-phase (I) and quadrature (Q) signal components. A digital signal processor (DSP) computes the ratio between the Q and I components, computes the phase of the RF signal (relative to that of the DLO signal) as the arctangent of this ratio, and then averages successive such phase values over a time interval specified by the user.

  10. Efficient Bayesian Phase Estimation.

    PubMed

    Wiebe, Nathan; Granade, Chris

    2016-07-01

    We introduce a new method called rejection filtering that we use to perform adaptive Bayesian phase estimation. Our approach has several advantages: it is classically efficient, easy to implement, achieves Heisenberg limited scaling, resists depolarizing noise, tracks time-dependent eigenstates, recovers from failures, and can be run on a field programmable gate array. It also outperforms existing iterative phase estimation algorithms such as Kitaev's method. PMID:27419551

  11. Efficient Bayesian Phase Estimation

    NASA Astrophysics Data System (ADS)

    Wiebe, Nathan; Granade, Chris

    2016-07-01

    We introduce a new method called rejection filtering that we use to perform adaptive Bayesian phase estimation. Our approach has several advantages: it is classically efficient, easy to implement, achieves Heisenberg limited scaling, resists depolarizing noise, tracks time-dependent eigenstates, recovers from failures, and can be run on a field programmable gate array. It also outperforms existing iterative phase estimation algorithms such as Kitaev's method.

  12. Estimating synchronization signal phase

    NASA Astrophysics Data System (ADS)

    Lyons, Robert G.; Lord, John D.

    2015-03-01

    To read a watermark from printed images requires that the watermarking system read correctly after affine distortions. One way to recover from affine distortions is to add a synchronization signal in the Fourier frequency domain and use this synchronization signal to estimate the applied affine distortion. Using the Fourier Magnitudes one can estimate the linear portion of the affine distortion. To estimate the translation one must first estimate the phase of the synchronization signal and then use phase correlation to estimate the translation. In this paper we provide a new method to measure the phase of the synchronization signal using only the data from the complex Fourier domain. This data is used to compute the linear portion, so it is quite convenient to estimate the phase without further data manipulation. The phase estimation proposed in this paper is computationally simple and provides a significant computational advantage over previous methods while maintaining similar accuracy. In addition, the phase estimation formula gives a general way to interpolate images in the complex frequency domain.

  13. Electron Holography: phases matter.

    PubMed

    Lichte, Hannes

    2013-06-01

    Essentially, all optics is wave optics, be it with light, X-rays, neutrons or electrons. The information transfer from the object to the image can only be understood in terms of waves given by amplitude and phase. However, phases are difficult to measure: for slowly oscillating waves such as sound or low-frequency electromagnetic waves, phases can be measured directly; for high frequencies this has to be done by heterodyne detection, i.e. superposition with a reference and averaging over time. In optics, this is called interferometry. Because interference is mostly very difficult to achieve, phases have often been considered 'hidden variables' seemingly pulling the strings from backstage, only visible by their action on the image intensity. This was almost the case in conventional Electron Microscopy with the phase differences introduced by an object. However, in the face of the urgent questions from solid state physics and materials science, these phases have to be determined precisely, because they encode the most dominant object properties, such as charge distributions and electromagnetic fields. After more than six decades of very patient advancement, electron interferometry and holography offer unprecedented analytical facilities down to an atomic scale. Akira Tonomura has prominently contributed to the present state. PMID:23620338

  14. Electron microscope phase enhancement

    DOEpatents

    Jin, Jian; Glaeser, Robert M.

    2010-06-15

    A microfabricated electron phase shift element is used for modifying the phase characteristics of an electron beam passing though its center aperture, while not affecting the more divergent portion of an incident beam to selectively provide a ninety-degree phase shift to the unscattered beam in the back focal plan of the objective lens, in order to realize Zernike-type, in-focus phase contrast in an electron microscope. One application of the element is to increase the contrast of an electron microscope for viewing weakly scattering samples while in focus. Typical weakly scattering samples include biological samples such as macromolecules, or perhaps cells. Preliminary experimental images demonstrate that these devices do apply a ninety degree phase shift as expected. Electrostatic calculations have been used to determine that fringing fields in the region of the scattered electron beams will cause a negligible phase shift as long as the ratio of electrode length to the transverse feature-size aperture is about 5:1. Calculations are underway to determine the feasibility of aspect smaller aspect ratios of about 3:1 and about 2:1.

  15. Compressed sensing phase retrieval with phase diversity

    NASA Astrophysics Data System (ADS)

    Qin, Shun; Hu, Xinqi; Qin, Qiong

    2014-01-01

    The compressed sensing (CS) theory shows that sparse signal can be reconstructed accurately with some randomly observed measurements that are much fewer than what traditional method requires. Since it takes structure of signals into consideration, it has many advantages in the structured signals process. With CS, measuring can be speeded up and the cost of hardware can be decreased significantly. However, it faces great challenge in the amplitude-only measurement. In this article, we study the magnitude-only compressed sensing phase retrieval (CSPR) problem, and propose a practical recovery algorithm. In our algorithm, we introduce the powerful Hybrid-Input-Output algorithm with phase diversity to make our algorithm robust and efficient. A relaxed ℓ0 norm constrain is also introduced to help PR find a sparse solution with fewer measurements, which is demonstrated to be essential and effective to CSPR. We finally successfully apply it into complex-valued object recovery in THz imaging. The numerical results show that the proposed algorithm can recover the object pretty well with fewer measurements than what PR traditionally requires.

  16. Introduction to phasing

    SciTech Connect

    Taylor, Garry L.

    2010-04-01

    This introductory paper to the CCP4 weekend on experimental phasing introduces the concept of the ‘phase problem’ for non-experts. Modern methods of phasing are explored, including some recent examples that can be downloaded as tutorials. When collecting X-ray diffraction data from a crystal, we measure the intensities of the diffracted waves scattered from a series of planes that we can imagine slicing through the crystal in all directions. From these intensities we derive the amplitudes of the scattered waves, but in the experiment we lose the phase information; that is, how we offset these waves when we add them together to reconstruct an image of our molecule. This is generally known as the ‘phase problem’. We can only derive the phases from some knowledge of the molecular structure. In small-molecule crystallography, some basic assumptions about atomicity give rise to relationships between the amplitudes from which phase information can be extracted. In protein crystallography, these ab initio methods can only be used in the rare cases in which there are data to at least 1.2 Å resolution. For the majority of cases in protein crystallography phases are derived either by using the atomic coordinates of a structurally similar protein (molecular replacement) or by finding the positions of heavy atoms that are intrinsic to the protein or that have been added (methods such as MIR, MIRAS, SIR, SIRAS, MAD, SAD or combinations of these). The pioneering work of Perutz, Kendrew, Blow, Crick and others developed the methods of isomorphous replacement: adding electron-dense atoms to the protein without disturbing the protein structure. Nowadays, methods from small-molecule crystallography can be used to find the heavy-atom substructure and the phases for the whole protein can be bootstrapped from this prior knowledge. More recently, improved X-ray sources, detectors and software have led to the routine use of anomalous scattering to obtain phase information from

  17. The NMR phased array.

    PubMed

    Roemer, P B; Edelstein, W A; Hayes, C E; Souza, S P; Mueller, O M

    1990-11-01

    We describe methods for simultaneously acquiring and subsequently combining data from a multitude of closely positioned NMR receiving coils. The approach is conceptually similar to phased array radar and ultrasound and hence we call our techniques the "NMR phased array." The NMR phased array offers the signal-to-noise ratio (SNR) and resolution of a small surface coil over fields-of-view (FOV) normally associated with body imaging with no increase in imaging time. The NMR phased array can be applied to both imaging and spectroscopy for all pulse sequences. The problematic interactions among nearby surface coils is eliminated (a) by overlapping adjacent coils to give zero mutual inductance, hence zero interaction, and (b) by attaching low input impedance preamplifiers to all coils, thus eliminating interference among next nearest and more distant neighbors. We derive an algorithm for combining the data from the phased array elements to yield an image with optimum SNR. Other techniques which are easier to implement at the cost of lower SNR are explored. Phased array imaging is demonstrated with high resolution (512 x 512, 48-cm FOV, and 32-cm FOV) spin-echo images of the thoracic and lumbar spine. Data were acquired from four-element linear spine arrays, the first made of 12-cm square coils and the second made of 8-cm square coils. When compared with images from a single 15 x 30-cm rectangular coil and identical imaging parameters, the phased array yields a 2X and 3X higher SNR at the depth of the spine (approximately 7 cm). PMID:2266841

  18. Combustion 2000: Phase II

    SciTech Connect

    Unknown

    1999-11-01

    The goals of the program are to develop a coal-fired high performance power generation system (HIPPS) that is capable of: thermal efficiency (HHV) {ge} 47%; NOx, SOx, and particulates {le} 10% NSPS (New Source Performance Standard); coal providing {ge} 65% of heat input; all solid wastes benign; and cost of electricity {le} 90% of present plants. Phase 1, which began in 1992, focused on the analysis of various configurations of indirectly fired cycles and on technical assessments of alternative plant subsystems and components, including performance requirements, developmental status, design options, complexity and reliability, and capital and operating costs. Phase 1 also included preliminary R and D and the preparation of designs for HIPPS commercial plants approximately 300 MWe in size. This Phase, Phase 2, had as its initial objective the development of a complete design base for the construction and operation of a HIPPS prototype plant to be constructed in Phase 3. As part of a descoping initiative, the Phase 3 program has been eliminated and work related to the commercial plant design has been ended. The rescoped program retained a program of engineering research and development focusing on high temperature heat exchangers, e.g. HITAF development (Task 2); a rescoped Task 6 that is pertinent to Vision 21 objectives and focuses on advanced cycle analysis and optimization, integration of gas turbines into complex cycles, and repowering designs; and preparation of the Phase 2 Technical Report (Task 8). This rescoped program deleted all subsystem testing (Tasks 3, 4,and 5) and the development of a site-specific engineering design and test plan for the HIPPS prototype plant (Task 7). Work reported herein is from: Task 2.1 HITAF Combustors; Task 2.2 HITAF Air Heaters; and Task 6 HIPPS Commercial Plant Design Update.

  19. Digital phase-lock loop

    NASA Technical Reports Server (NTRS)

    Thomas, Jr., Jess B. (Inventor)

    1991-01-01

    An improved digital phase lock loop incorporates several distinctive features that attain better performance at high loop gain and better phase accuracy. These features include: phase feedback to a number-controlled oscillator in addition to phase rate; analytical tracking of phase (both integer and fractional cycles); an amplitude-insensitive phase extractor; a more accurate method for extracting measured phase; a method for changing loop gain during a track without loss of lock; and a method for avoiding loss of sampled data during computation delay, while maintaining excellent tracking performance. The advantages of using phase and phase-rate feedback are demonstrated by comparing performance with that of rate-only feedback. Extraction of phase by the method of modeling provides accurate phase measurements even when the number-controlled oscillator phase is discontinuously updated.

  20. Two Phase Streaming Potentials

    SciTech Connect

    Marsden, S S; Wheatall, M W

    1987-01-20

    The streaming potentials generated by the flow of both liquid and gas through either a Pyrex capillary tube or else an unconsolidated Pyrex porous medium were investigated. This mixture of distilled water plus nitrogen gas simulated wet stream but allowed experiments to be run at room temperature. Single-phase flow of distilled water alone resulted in a constant voltage-to-pressure drop ratio, E/Δp, of +0.15 v/psi for the capillary tube and -0.52 v/psi for the porous medium. For both single- and two-phase flow through the capillary tube, the upstream potential was always positive relative to the downstream electrode while the opposite was true for the porous medium. The maximum two-phase potentials generated in the porous medium were about four times as great as those generated in the capillary tube for similar gas fractions, Γ. For the capillary tube experiments the potentials generated when Γ < ≈ 0.5 were equal to or slightly less than those for single-phase flow, while for the porous medium the potentials were always greater than those for single-phase flow. When Γ > ≈ 0.5 for both kinds of flow systems Γ had a profound effect on streaming potential and reached a pronounced maximum when 0.94 < Γ < 0.99. The implications of these streaming potentials for geothermal exploration and delineation of geothermal reservoirs is also discussed in the paper. 7 figs., 10 refs.

  1. Single-phase to three-phase power conversion interface

    NASA Astrophysics Data System (ADS)

    Wu, Jinn-Chang; Wang, Yung-Shan; Jou, Hurng-Liahng; Lu, Wei-Tso

    2016-07-01

    This study proposes a single-phase to three-phase power conversion interface which converts the power from a single-phase utility to three-phase power for a three-phase load. The proposed single-phase to three-phase power conversion interface comprises a bridge-type switch set, a set of three-phase inductors, a transformer set and a set of three-phase capacitors. A current-mode control controls the switching of bridge-type switch set, to generate a set of nonzero-sequence (NZS) currents and a set of zero-sequence (ZS) currents. The transformer set is used to decouple the NZS currents and the ZS currents. The NZS currents are used to generate a high-quality three-phase voltage that supplies power to a three-phase load. The ZS currents flow to the single-phase utility so that the utility current is sinusoidal and in phase with the utility voltage. Accordingly, only a bridge-type switch set is used in the single-phase to three-phase power conversion interface to simply the power circuit. A prototype is developed and tested to verify the performance of the proposed single-phase to three-phase power conversion interface.

  2. Kirchhoff migration without phases

    NASA Astrophysics Data System (ADS)

    Bardsley, Patrick; Guevara Vasquez, Fernando

    2016-10-01

    We present a simple, frequency domain, preprocessing step to Kirchhoff migration that allows the method to image scatterers when the wave field phase information is lost at the receivers, and only intensities are measured. The resulting imaging method does not require knowing the phases of the probing field or manipulating the phase of the wave field at the receivers. In a regime where the scattered field is small compared to the probing field, the problem of recovering the full-waveform scattered field from intensity data can be formulated as an embarrassingly simple least-squares problem. Although this only recovers the projection (on a known subspace) of the full-waveform scattered field, we show that, for high frequencies, this projection gives Kirchhoff images asymptotically identical to the images obtained with full waveform data. Our method can also be used when the source is modulated by a Gaussian process and autocorrelations are measured at an array of receivers.

  3. Phase trombones with bending

    SciTech Connect

    Courant, E.D.; Garren, A.

    1985-10-01

    The phase shifting trombones considered up to now for SSC application consisted of sets of evenly spaced quadrupoles separated by drift spaces. One such trombone was placed between a dispersion suppressor and a crossing insertion, so that the trombone had zero dispersion. With such trombones, it is possible to change {beta}{sup *} at constant tune, or to change the tunes by several units without altering the cell phase advances in the arcs. An objection to the above type of phase trombone is that it adds to the circumference, since no bending is included. This objection may or may not be valid depending on the potential usefulness of the drift spaces in them. In this note the authors show an alternative trombone design in which dipoles are included between the quadrupoles as in the normal arc cells. Since these trombones have dispersion, they are placed at the ends of the arcs, to be followed in turn by the dispersion suppressors and crossing insertions.

  4. Controllable tomography phase microscopy

    NASA Astrophysics Data System (ADS)

    Xiu, Peng; Zhou, Xin; Kuang, Cuifang; Xu, Yingke; Liu, Xu

    2015-03-01

    Tomography phase microscopy (TPM) is a new microscopic method that can quantitatively yield the volumetric 3D distribution of a sample's refractive index (RI), which is significant for cell biology research. In this paper, a controllable TPM system is introduced. In this system a circulatory phase-shifting method and piezoelectric ceramic are used which enable the TPM system to record the 3D RI distribution at a more controllable speed, from 1 to 40 fps, than in the other TPM systems reported. The resolution of the RI distribution obtained by this controllable TPM is much better than that in images recorded by phase contrast microscopy and interference tomography microscopy. The realization of controllable TPM not only allows for the application of TPM to the measurement of kinds of RI sample, but also contributes to academic and technological support for the practical use of TPM.

  5. Phase diagram of QCD

    SciTech Connect

    Halasz, M.A.; Verbaarschot, J.J.; Jackson, A.D.; Shrock, R.E.; Stephanov, M.A.

    1998-11-01

    We analyze the phase diagram of QCD with two massless quark flavors in the space of temperature T and chemical potential of the baryon charge {mu} using available experimental knowledge of QCD, insights gained from various models, as well as general and model independent arguments including continuity, universality, and thermodynamic relations. A random matrix model is used to describe the chiral symmetry restoration phase transition at finite T and {mu}. In agreement with general arguments, this model predicts a tricritical point in the T{mu} plane. Certain critical properties at such a point are universal and can be relevant to heavy ion collision experiments. {copyright} {ital 1998} {ital The American Physical Society}

  6. Compressive Phase Contrast Tomography

    SciTech Connect

    Maia, Filipe; MacDowell, Alastair; Marchesini, Stefano; Padmore, Howard A.; Parkinson, Dula Y.; Pien, Jack; Schirotzek, Andre; Yang, Chao

    2010-09-01

    When x-rays penetrate soft matter, their phase changes more rapidly than their amplitude. Interference effects visible with high brightness sources creates higher contrast, edge enhanced images. When the object is piecewise smooth (made of big blocks of a few components), such higher contrast datasets have a sparse solution. We apply basis pursuit solvers to improve SNR, remove ring artifacts, reduce the number of views and radiation dose from phase contrast datasets collected at the Hard X-Ray Micro Tomography Beamline at the Advanced Light Source. We report a GPU code for the most computationally intensive task, the gridding and inverse gridding algorithm (non uniform sampled Fourier transform).

  7. Linear phase compressive filter

    DOEpatents

    McEwan, Thomas E.

    1995-01-01

    A phase linear filter for soliton suppression is in the form of a laddered series of stages of non-commensurate low pass filters with each low pass filter having a series coupled inductance (L) and a reverse biased, voltage dependent varactor diode, to ground which acts as a variable capacitance (C). L and C values are set to levels which correspond to a linear or conventional phase linear filter. Inductance is mapped directly from that of an equivalent nonlinear transmission line and capacitance is mapped from the linear case using a large signal equivalent of a nonlinear transmission line.

  8. Linear phase compressive filter

    DOEpatents

    McEwan, T.E.

    1995-06-06

    A phase linear filter for soliton suppression is in the form of a laddered series of stages of non-commensurate low pass filters with each low pass filter having a series coupled inductance (L) and a reverse biased, voltage dependent varactor diode, to ground which acts as a variable capacitance (C). L and C values are set to levels which correspond to a linear or conventional phase linear filter. Inductance is mapped directly from that of an equivalent nonlinear transmission line and capacitance is mapped from the linear case using a large signal equivalent of a nonlinear transmission line. 2 figs.

  9. Quantum phase slip noise

    NASA Astrophysics Data System (ADS)

    Semenov, Andrew G.; Zaikin, Andrei D.

    2016-07-01

    Quantum phase slips (QPSs) generate voltage fluctuations in superconducting nanowires. Employing the Keldysh technique and making use of the phase-charge duality arguments, we develop a theory of QPS-induced voltage noise in such nanowires. We demonstrate that quantum tunneling of the magnetic flux quanta across the wire yields quantum shot noise which obeys Poisson statistics and is characterized by a power-law dependence of its spectrum SΩ on the external bias. In long wires, SΩ decreases with increasing frequency Ω and vanishes beyond a threshold value of Ω at T →0 . The quantum coherent nature of QPS noise yields nonmonotonous dependence of SΩ on T at small Ω .

  10. Phase interpolation circuits using frequency multiplication for phased arrays

    NASA Technical Reports Server (NTRS)

    Caron, P. R.; Mailloux, R. J.

    1970-01-01

    Antenna phasing circuit is described with the following advantages - 1/ increased number of phased elements, 2/ current repetition for each array element, 3/ circuit simplicity, and 4/ accurate phase interpolation. This circuit functions with Huggins Scan or with nearly any other phasing system.

  11. Phase change compositions

    DOEpatents

    Salyer, Ival O.

    1989-01-01

    Compositions containing crystalline, straight chain, alkyl hydrocarbons as phase change materials including cementitious compositions containing the alkyl hydrocarbons neat or in pellets or granules formed by incorporating the alkyl hydrocarbons in polymers or rubbers; and polymeric or elastomeric compositions containing alkyl hydrocarbons.

  12. Phase change compositions

    DOEpatents

    Salyer, Ival O.; Griffen, Charles W.

    1986-01-01

    Compositions containing crystalline, long chain, alkyl hydrocarbons as phase change materials including cementitious compositions containing the alkyl hydrocarbons neat or in pellets or granules formed by incorporating the alkyl hydrocarbons in polymers or rubbers; and polymeric or elastomeric compositions containing alkyl hydrocarbons.

  13. MAD phasing with krypton.

    PubMed

    Cohen, A; Ellis, P; Kresge, N; Soltis, S M

    2001-02-01

    Experiments demonstrating the feasibility of Kr-edge MAD on frozen crystals as a routine method for structure determination are reported. Approximately 50% of protein crystals can be successfully derivatized by pressurization with the noble gases xenon or krypton. While Xe has produced many useful derivatives for MIR phasing over the last several years, the Xe edges (K edge = 34.6 keV, L(I) = 5.5 keV) are not easily accessible for MAD studies. As the Kr K edge (14.3 keV) is accessible on most MAD beamlines, Kr derivatization provides the additional opportunity to conduct a MAD experiment and obtain phases using only a single crystal. This paper describes the phasing of two proteins using Kr MAD: the 17 kDa Fe protein myoglobin (Mb) from sperm whale (Physeter catodon) and an 18 kDa protein (SP18) from green abalone (Haliotis fulgens). Three-wavelength data were collected at SSRL beamline 9-2 from crystals of Mb and SP18 incubated in 2.76 MPa of Kr gas for 2 min, depressurized and then flash-frozen in a stream of nitrogen gas at 100 K. MAD phases were calculated using the program SHARP and the resulting density improved with wARP. The final maps for both Mb and SP18 were of excellent quality.

  14. Advanced Virgo phase cameras

    NASA Astrophysics Data System (ADS)

    van der Schaaf, L.; Agatsuma, K.; van Beuzekom, M.; Gebyehu, M.; van den Brand, J.

    2016-05-01

    A century after the prediction of gravitational waves, detectors have reached the sensitivity needed to proof their existence. One of them, the Virgo interferometer in Pisa, is presently being upgraded to Advanced Virgo (AdV) and will come into operation in 2016. The power stored in the interferometer arms raises from 20 to 700 kW. This increase is expected to introduce higher order modes in the beam, which could reduce the circulating power in the interferometer, limiting the sensitivity of the instrument. To suppress these higher-order modes, the core optics of Advanced Virgo is equipped with a thermal compensation system. Phase cameras, monitoring the real-time status of the beam constitute a critical component of this compensation system. These cameras measure the phases and amplitudes of the laser-light fields at the frequencies selected to control the interferometer. The measurement combines heterodyne detection with a scan of the wave front over a photodetector with pin-hole aperture. Three cameras observe the phase front of these laser sidebands. Two of them monitor the in-and output of the interferometer arms and the third one is used in the control of the aberrations introduced by the power recycling cavity. In this paper the working principle of the phase cameras is explained and some characteristic parameters are described.

  15. SSIP Phase I Roadmap

    ERIC Educational Resources Information Center

    Vinh, Megan; Lucas, Anne; Taylor, Cornelia; Kelley, Grace; Kasprzak, Christina

    2014-01-01

    This roadmap provides a description of the activities involved in the development of the State Systemic Improvement Plan (SSIP) (SPP/APR Indicators C11 and B17) due to the Office of Special Education Programs (OSEP) on April 1, 2015. The roadmap is intended to support states with completing Phase I of the SSIP process. This document provides…

  16. String mediated phase transitions

    NASA Technical Reports Server (NTRS)

    Copeland, ED; Haws, D.; Rivers, R.; Holbraad, S.

    1988-01-01

    It is demonstrated from first principles how the existence of string-like structures can cause a system to undergo a phase transition. In particular, the role of topologically stable cosmic string in the restoration of spontaneously broken symmetries is emphasized. How the thermodynamic properties of strings alter when stiffness and nearest neighbor string-string interactions are included is discussed.

  17. DELTA PHASE PLUTONIUM ALLOYS

    DOEpatents

    Cramer, E.M.; Ellinger, F.H.; Land. C.C.

    1960-03-22

    Delta-phase plutonium alloys were developed suitable for use as reactor fuels. The alloys consist of from 1 to 4 at.% zinc and the balance plutonium. The alloys have good neutronic, corrosion, and fabrication characteristics snd possess good dimensional characteristics throughout an operating temperature range from 300 to 490 deg C.

  18. Fun with Phase Changes

    ERIC Educational Resources Information Center

    Purvis, David

    2006-01-01

    A lot of good elementary science involves studying solids, liquids, and gases, and some inquiry-based activities that are easy to set up and do. In this article, the author presents activities pertaining to simple phase change. Using water as the example, these activities introduce upper-grade students to the idea of the arrangement of molecules…

  19. Introduction to phasing

    PubMed Central

    Taylor, Garry L.

    2010-01-01

    When collecting X-ray diffraction data from a crystal, we measure the intensities of the diffracted waves scattered from a series of planes that we can imagine slicing through the crystal in all directions. From these intensities we derive the amplitudes of the scattered waves, but in the experiment we lose the phase information; that is, how we offset these waves when we add them together to reconstruct an image of our molecule. This is generally known as the ‘phase problem’. We can only derive the phases from some knowledge of the molecular structure. In small-molecule crystallography, some basic assumptions about atomicity give rise to relationships between the amplitudes from which phase information can be extracted. In protein crystallography, these ab initio methods can only be used in the rare cases in which there are data to at least 1.2 Å resolution. For the majority of cases in protein crystallography phases are derived either by using the atomic coordinates of a structurally similar protein (molecular replacement) or by finding the positions of heavy atoms that are intrinsic to the protein or that have been added (methods such as MIR, MIRAS, SIR, SIRAS, MAD, SAD or com­binations of these). The pioneering work of Perutz, Kendrew, Blow, Crick and others developed the methods of isomorphous replacement: adding electron-dense atoms to the protein without disturbing the protein structure. Nowadays, methods from small-molecule crystallography can be used to find the heavy-atom substructure and the phases for the whole protein can be bootstrapped from this prior knowledge. More recently, improved X-ray sources, detectors and software have led to the routine use of anomalous scattering to obtain phase information from either incorporated selenium or intrinsic sulfurs. In the best cases, only a single set of X-ray data (SAD) is required to provide the positions of the anomalous scatters, which together with density-modification procedures can reveal

  20. Phase II Final Report

    SciTech Connect

    Schuknecht, Nate; White, David; Hoste, Graeme

    2014-09-11

    The SkyTrough DSP will advance the state-of-the-art in parabolic troughs for utility applications, with a larger aperture, higher operating temperature, and lower cost. The goal of this project was to develop a parabolic trough collector that enables solar electricity generation in the 2020 marketplace for a 216MWe nameplate baseload power plant. This plant requires an LCOE of 9¢/kWhe, given a capacity factor of 75%, a fossil fuel limit of 15%, a fossil fuel cost of $6.75/MMBtu, $25.00/kWht thermal storage cost, and a domestic installation corresponding to Daggett, CA. The result of our optimization was a trough design of larger aperture and operating temperature than has been fielded in large, utility scale parabolic trough applications: 7.6m width x 150m SCA length (1,118m2 aperture), with four 90mm diameter × 4.7m receivers per mirror module and an operating temperature of 500°C. The results from physical modeling in the System Advisory Model indicate that, for a capacity factor of 75%: The LCOE will be 8.87¢/kWhe. SkyFuel examined the design of almost every parabolic trough component from a perspective of load and performance at aperture areas from 500 to 2,900m2. Aperture-dependent design was combined with fixed quotations for similar parts from the commercialized SkyTrough product, and established an installed cost of $130/m2 in 2020. This project was conducted in two phases. Phase I was a preliminary design, culminating in an optimum trough size and further improvement of an advanced polymeric reflective material. This phase was completed in October of 2011. Phase II has been the detailed engineering design and component testing, which culminated in the fabrication and testing of a single mirror module. Phase II is complete, and this document presents a summary of the comprehensive work.

  1. 78 FR 33911 - Phased Retirement

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-05

    ... is computed during and after phased retirement, and how employees fully retire from phased retirement... compute phased retirement annuities under 5 U.S.C. 8336a. Sections 831.1701 through 831.1703 explain the... hours beyond the working percentage used to compute the phased retirement annuity. In promulgating...

  2. Noisy quantum phase communication channels

    NASA Astrophysics Data System (ADS)

    Teklu, Berihu; Trapani, Jacopo; Olivares, Stefano; Paris, Matteo G. A.

    2015-06-01

    We address quantum phase channels, i.e communication schemes where information is encoded in the phase-shift imposed to a given signal, and analyze their performances in the presence of phase diffusion. We evaluate mutual information for coherent and phase-coherent signals, and for both ideal and realistic phase receivers. We show that coherent signals offer better performances than phase-coherent ones, and that realistic phase channels are effective ones in the relevant regime of low energy and large alphabets.

  3. Multicomponent three-phase equilibria

    SciTech Connect

    Ho, C.K.

    1995-06-01

    This paper presents the relations that describe thermodynamic equilibrium in a three-phase system. Multiple components, including air, water, and oil components, are considered in three phases: (1) aqueous, (2) oil, and (3) gas. Primary variables are specified for each of seven possible phase combinations. These primary variables are then used to determine the necessary secondary variables to completely describe the system. Criteria are also developed to check the stability of each phase configuration and determine possible transitions from one phase configuration to another phase configuration via phase appearances and disappearances.

  4. Extreme Ultraviolet Phase Contrast Imaging

    SciTech Connect

    Denbeaux, Gregory; Garg, Rashi; Aquila, Andy; Barty, Anton; Goldberg, Kenneth; Gullikson, Eric; Liu, Yanwei; Wood, Obert

    2005-11-01

    The conclusions of this report are: (1) zone plate microscopy provides high resolution imaging of EUV masks; (2) using phase plates in the back focal plane of the objective lens can provide contrast mechanisms for measurement of the phase shift from defects on the mask; (3) the first high resolution EUV Zernike phase contrast images have been acquired; and (4) future work will include phase contrast mode in reflection from an EUV mask to directly measure the reflectivity and phase shift from defects.

  5. Broadband Interferometer for Measuring Transmitted Wavefronts of Optical Bandpass Filters for HST (ACS)

    NASA Technical Reports Server (NTRS)

    Boucarut, R. A.; Leviton, D. B.

    1998-01-01

    The transmitted wavefronts of optical filters for the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) are characterized using the Wildly and Openly Modified Broadband Achromatic Twyman Green (WOMBAT) Interferometer developed in the NASA/GSFC Optics Branch's Diffraction Grating Evaluation Facility (DGEF). Because only four of thirty-three of ACS's optical bandpass filters transmit the 633 nm light of most commercial interferometers, a broadband interferometer is required to verify specified transmitted wavefront of ACS filters. WOMBAT's design is a hybrid of the BAT interferometer developed by JPL used for HST Wide Field and Planetary Camera 2 (WFPC-2) filters and a WYKO 400 phase shifting interferometer. It includes a broadband light source, monochromator, off-axis, parabolic collimating and camera mirrors, an aluminum-coated fused silica beam splitter, flat retroreflecting mirrors for the test and reference arms, and a LTV-sensitive CCD camera. An outboarded, piezo-electric phase shifter holds the flat mirror in the interferometer's reference arm. The interferometer is calibrated through interaction between the WYKO system's software and WONMAT hardware for the test wavelength of light entering the beam splitter. Phase-shifted interferograms of the filter mounted in the test arm are analyzed using WYKO's Vision' software. Filters as large as 90 mm in diameter have been measured over a wavelength range from 200 to 1100 nm with a sensitivity of lambda/200 rms at lambda = 633 nm. Results of transmitted wavefront measurements are shown for ACS fixed band pass and spatially-variable bandpass filters for a variety of wavelengths.

  6. Phase-field modeling of multi-phase solidification

    NASA Astrophysics Data System (ADS)

    Nestler, Britta; Wheeler, Adam A.

    2002-08-01

    A phase-field model for a general class of multi-phase metallic alloys is now proposed which describes both multi-phase solidification phenomena as well as polycrystalline grain structures. The model serves as a computational method to simulate the motion and kinetics of multiple phase boundaries and enables the visualization of the diffusion processes and of the phase transitions in multi-phase systems. Numerical simulations are presented which illustrate the capability of the phase-field model to recover a variety of complex experimental growth structures. In particular, the phase-field model can be used to simulate microstructure evolutions in eutectic, peritectic and monotectic alloys. In addition, polycrystalline grain structures with effects such as wetting, grain growth, symmetry properties of adjacent triple junctions in thin film samples and stability criteria at multiple junctions are described by phase-field simulations.

  7. Spatial Phase Imaging

    NASA Technical Reports Server (NTRS)

    2006-01-01

    Frequently, scientists grow crystals by dissolving a protein in a specific liquid solution, and then allowing that solution to evaporate. The methods used next have been, variously, invasive (adding a dye that is absorbed by the protein), destructive (crushing protein/salt-crystal mixtures and observing differences between the crushing of salt and protein), or costly and time-consuming (X-ray crystallography). In contrast to these methods, a new technology for monitoring protein growth, developed in part through NASA Small Business Innovation Research (SBIR) funding from Marshall Space Flight Center, is noninvasive, nondestructive, rapid, and more cost effective than X-ray analysis. The partner for this SBIR, Photon-X, Inc., of Huntsville, Alabama, developed spatial phase imaging technology that can monitor crystal growth in real time and in an automated mode. Spatial phase imaging scans for flaws quickly and produces a 3-D structured image of a crystal, showing volumetric growth analysis for future automated growth.

  8. Phase calibration generator

    NASA Technical Reports Server (NTRS)

    Sigman, E. H.

    1988-01-01

    A phase calibration system was developed for the Deep Space Stations to generate reference microwave comb tones which are mixed in with signals received by the antenna. These reference tones are used to remove drifts of the station's receiving system from the detected data. This phase calibration system includes a cable stabilizer which transfers a 20 MHz reference signal from the control room to the antenna cone. The cable stabilizer compensates for delay changes in the long cable which connects its control room subassembly to its antenna cone subassembly in such a way that the 20 MHz is transferred to the cone with no significant degradation of the hydrogen maser atomic clock stability. The 20 MHz reference is used by the comb generator and is also available for use as a reference for receiver LO's in the cone.

  9. Nucleosome phasing - new insights

    NASA Astrophysics Data System (ADS)

    Chereji, Razvan

    2014-03-01

    Eukaryotic genomes are organized into arrays of nucleosomes, in which stretches of 147 base-pairs of DNA are wrapped around octameric histones. Recently, a new method of mapping nucleosome positions was developed, which gives a much higher accuracy than the typical MNase-seq method. I present a statistical mechanics model which is able to reproduce the high-resolution nucleosome positioning data. I show that the DNA sequence is not the main cause of the nucleosome phasing which is observed genome-wide, and I present the major nucleosome phasing elements. The statistical mechanics framework is general enough to be useful in explaining different experimental observations, and I present a few results of this model.

  10. Measurement by phase severance

    SciTech Connect

    Noyes, H.P.

    1987-03-01

    It is claimed that the measurement process is more accurately described by ''quasi-local phase severance'' than by ''wave function collapse''. The approach starts from the observation that the usual route to quantum mechanics starting from the Hamilton-Jacobi equations throws away half the degrees of freedom, namely, the classical initial state parameters. To overcome this difficulty, the full set of Hamilton-Jacobi equations is interpreted as operator equations acting on a state vector. The measurement theory presented is based on the conventional S-matrix boundary condition of N/sub A/ free particles in the distant past and N/sub B/ free particles in the distant future and taking the usual free particle wave functions, multiplied by phase factors.

  11. Phase shifting interferometer

    DOEpatents

    Sommargren, G.E.

    1999-08-03

    An interferometer is disclosed which has the capability of measuring optical elements and systems with an accuracy of {lambda}/1000 where {lambda} is the wavelength of visible light. Whereas current interferometers employ a reference surface, which inherently limits the accuracy of the measurement to about {lambda}/50, this interferometer uses an essentially perfect spherical reference wavefront generated by the fundamental process of diffraction. Whereas current interferometers illuminate the optic to be tested with an aberrated wavefront which also limits the accuracy of the measurement, this interferometer uses an essentially perfect spherical measurement wavefront generated by the fundamental process of diffraction. This interferometer is adjustable to give unity fringe visibility, which maximizes the signal-to-noise, and has the means to introduce a controlled prescribed relative phase shift between the reference wavefront and the wavefront from the optics under test, which permits analysis of the interference fringe pattern using standard phase extraction algorithms. 11 figs.

  12. Phase shifting interferometer

    DOEpatents

    Sommargren, Gary E.

    1999-01-01

    An interferometer which has the capability of measuring optical elements and systems with an accuracy of .lambda./1000 where .lambda. is the wavelength of visible light. Whereas current interferometers employ a reference surface, which inherently limits the accuracy of the measurement to about .lambda./50, this interferometer uses an essentially perfect spherical reference wavefront generated by the fundamental process of diffraction. Whereas current interferometers illuminate the optic to be tested with an aberrated wavefront which also limits the accuracy of the measurement, this interferometer uses an essentially perfect spherical measurement wavefront generated by the fundamental process of diffraction. This interferometer is adjustable to give unity fringe visibility, which maximizes the signal-to-noise, and has the means to introduce a controlled prescribed relative phase shift between the reference wavefront and the wavefront from the optics under test, which permits analysis of the interference fringe pattern using standard phase extraction algorithms.

  13. Phase shifting diffraction interferometer

    DOEpatents

    Sommargren, G.E.

    1996-08-29

    An interferometer which has the capability of measuring optical elements and systems with an accuracy of {lambda}/1000 where {lambda} is the wavelength of visible light. Whereas current interferometers employ a reference surface, which inherently limits the accuracy of the measurement to about {lambda}/50, this interferometer uses an essentially perfect spherical reference wavefront generated by the fundamental process of diffraction. This interferometer is adjustable to give unity fringe visibility, which maximizes the signal-to-noise, and has the means to introduce a controlled prescribed relative phase shift between the reference wavefront and the wavefront from the optics under test, which permits analysis of the interference fringe pattern using standard phase extraction algorithms. 8 figs.

  14. Phase shifting diffraction interferometer

    DOEpatents

    Sommargren, Gary E.

    1996-01-01

    An interferometer which has the capability of measuring optical elements and systems with an accuracy of .lambda./1000 where .lambda. is the wavelength of visible light. Whereas current interferometers employ a reference surface, which inherently limits the accuracy of the measurement to about .lambda./50, this interferometer uses an essentially perfect spherical reference wavefront generated by the fundamental process of diffraction. This interferometer is adjustable to give unity fringe visibility, which maximizes the signal-to-noise, and has the means to introduce a controlled prescribed relative phase shift between the reference wavefront and the wavefront from the optics under test, which permits analysis of the interference fringe pattern using standard phase extraction algorithms.

  15. Phase space quantum mechanics

    NASA Astrophysics Data System (ADS)

    Błaszak, Maciej; Domański, Ziemowit

    2012-02-01

    This paper develops an alternative formulation of quantum mechanics known as the phase space quantum mechanics or deformation quantization. It is shown that the quantization naturally arises as an appropriate deformation of the classical Hamiltonian mechanics. More precisely, the deformation of the point-wise product of observables to an appropriate noncommutative ⋆-product and the deformation of the Poisson bracket to an appropriate Lie bracket are the key elements in introducing the quantization of classical Hamiltonian systems. The formalism of the phase space quantum mechanics is presented in a very systematic way for the case of any smooth Hamiltonian function and for a very wide class of deformations. The considered class of deformations and the corresponding ⋆-products contains as a special case all deformations which can be found in the literature devoted to the subject of the phase space quantum mechanics. Fundamental properties of ⋆-products of observables, associated with the considered deformations are presented as well. Moreover, a space of states containing all admissible states is introduced, where the admissible states are appropriate pseudo-probability distributions defined on the phase space. It is proved that the space of states is endowed with a structure of a Hilbert algebra with respect to the ⋆-multiplication. The most important result of the paper shows that developed formalism is more fundamental than the axiomatic ordinary quantum mechanics which appears in the presented approach as the intrinsic element of the general formalism. The equivalence of two formulations of quantum mechanics is proved by observing that the Wigner-Moyal transform has all properties of the tensor product. This observation allows writing many previous results found in the literature in a transparent way, from which the equivalence of the two formulations of quantum mechanics follows naturally. In addition, examples of a free particle and a simple harmonic

  16. Phase Field Fracture Mechanics.

    SciTech Connect

    Robertson, Brett Anthony

    2015-11-01

    For this assignment, a newer technique of fracture mechanics using a phase field approach, will be examined and compared with experimental data for a bend test and a tension test. The software being used is Sierra Solid Mechanics, an implicit/explicit finite element code developed at Sandia National Labs in Albuquerque, New Mexico. The bend test experimental data was also obtained at Sandia Labs while the tension test data was found in a report online from Purdue University.

  17. Solid phase extraction membrane

    DOEpatents

    Carlson, Kurt C [Nashville, TN; Langer, Roger L [Hudson, WI

    2002-11-05

    A wet-laid, porous solid phase extraction sheet material that contains both active particles and binder and that possesses excellent wet strength is described. The binder is present in a relatively small amount while the particles are present in a relatively large amount. The sheet material is sufficiently strong and flexible so as to be pleatable so that, for example, it can be used in a cartridge device.

  18. [Advanced sleep phase syndrome].

    PubMed

    Ondzé, B; Espa, F; Ming, L C; Chakkar, B; Besset, A; Billiard, M

    2001-11-01

    The Advanced Sleep Phase Syndrome (ASPS) is a sleep disorder characterized by an early sleep onset and early awakening without any disturbance of the sleep structure. The management of this disease requires clinical and laboratory investigations in an attempt to confirm the phase advance of body core temperature and melatonin rhythm. The use of light therapy, possibly associated with chronotherapy or melatonin intake has been proposed. The evolution is variable. Seven subjects, aged 15 to 72 were diagnosed in our sleep disorders unit by mean of sleep log, actigraphy, sleep and temperature recording. The sleep onset and sleep offset times were approximately the same according to sleep log, actigraphy and night polysomnography. The nadir of body core temperature was at 01:38 +/- 01:03. Two familial cases were identified of which 1 was investigated in constant routine condition with hourly blood sampling. An advanced phase of melatonin and cortisol was evidenced. The disease temporarily improved in 3 cases with light therapy and in one case with the association of light therapy and chronotherapy. These data show the difficulties of the management and the treatment of this rarely diagnosed disease. PMID:11924025

  19. Compactification on phase space

    NASA Astrophysics Data System (ADS)

    Lovelady, Benjamin; Wheeler, James

    2016-03-01

    A major challenge for string theory is to understand the dimensional reduction required for comparison with the standard model. We propose reducing the dimension of the compactification by interpreting some of the extra dimensions as the energy-momentum portion of a phase-space. Such models naturally arise as generalized quotients of the conformal group called biconformal spaces. By combining the standard Kaluza-Klein approach with such a conformal gauge theory, we may start from the conformal group of an n-dimensional Euclidean space to form a 2n-dimensional quotient manifold with symplectic structure. A pair of involutions leads naturally to two n-dimensional Lorentzian manifolds. For n = 5, this leaves only two extra dimensions, with a countable family of possible compactifications and an SO(5) Yang-Mills field on the fibers. Starting with n=6 leads to 4-dimensional compactification of the phase space. In the latter case, if the two dimensions each from spacetime and momentum space are compactified onto spheres, then there is an SU(2)xSU(2) (left-right symmetric electroweak) field between phase and configuration space and an SO(6) field on the fibers. Such a theory, with minor additional symmetry breaking, could contain all parts of the standard model.

  20. Coherence, phase differences, phase shift, and phase lock in EEG/ERP analyses.

    PubMed

    Thatcher, Robert W

    2012-01-01

    Electroencephalogram (EEG) coherence is a mixture of phase locking interrupted by phase shifts in the spontaneous EEG. Average reference, Laplacian transforms, and independent component (ICA) reconstruction of time series can distort physiologically generated phase differences and invalidate the computation of coherence and phase differences as well as in the computation of directed coherence and phase reset. Time domain measures of phase shift and phase lock are less prone to artifact and are independent of volume conduction. Cross-frequency synchrony in the surface EEG and in Low Resolution Electromagnetic Tomography (LORETA) provides insights into dynamic functions of the brain.

  1. Phases, phase equilibria, and phase rules in low-dimensional systems

    SciTech Connect

    Frolov, T.; Mishin, Y.

    2015-07-28

    We present a unified approach to thermodynamic description of one, two, and three dimensional phases and phase transformations among them. The approach is based on a rigorous definition of a phase applicable to thermodynamic systems of any dimensionality. Within this approach, the same thermodynamic formalism can be applied for the description of phase transformations in bulk systems, interfaces, and line defects separating interface phases. For both lines and interfaces, we rigorously derive an adsorption equation, the phase coexistence equations, and other thermodynamic relations expressed in terms of generalized line and interface excess quantities. As a generalization of the Gibbs phase rule for bulk phases, we derive phase rules for lines and interfaces and predict the maximum number of phases than may coexist in systems of the respective dimensionality.

  2. Symmetry in DIET phase transitions

    NASA Astrophysics Data System (ADS)

    Zhang, J. P.; Marks, L. D.

    1989-11-01

    Analysis of the route of the phase transitions in transition metal oxides driven by DIET of oxygen from the surfaces observed by high resolution electron microscopy indicates that there is a symmetry selection rule. The phase transitions are to a structure with a higher point group symmetry where the new phase with a lower oxygen content is either one with a supergroup symmetry with respect to the original phase, or is an amorphous intermediary. The final phase has the highest symmetry and is also a metallic conductor. If a possible lower oxygen content phase does not have the correct supergroup symmetry, it is not formed. It is also found that the point group is conserved during the phase transition if the oxide belongs to the highest groups O h or D 6h. This symmetry selection rule can therefore be used to predict the route of the phase transition. The symmetry rule operates when the phase transition is diffusional.

  3. Reconstructions of phase contrast, phased array multicoil data.

    PubMed

    Bernstein, M A; Grgic, M; Brosnan, T J; Pelc, N J

    1994-09-01

    We present a reconstruction method for phased array multicoil data that is compatible with phase contrast MR angiography. The proposed algorithm can produce either complex difference or phase difference angiograms. Directional flow and quantitative information are preserved with the phase difference reconstruction. The proposed method is computationally efficient and avoids intercoil cancellation errors near the velocity aliasing boundary. Feasibility of the method is demonstrated on human scans.

  4. Organometallic complexes with biological molecules. XVIII. Alkyltin(IV) cephalexinate complexes: synthesis, solid state and solution phase investigations.

    PubMed

    Di Stefano, R; Scopelliti, M; Pellerito, C; Casella, G; Fiore, T; Stocco, G C; Vitturi, R; Colomba, M; Ronconi, L; Sciacca, I D; Pellerito, L

    2004-03-01

    Dialkyltin(IV) and trialkyltin(IV) complexes of the deacetoxycephalo-sporin-antibiotic cephalexin [7-(d-2-amino-2-phenylacetamido)-3-methyl-3-cephem-4-carboxylic acid] (Hceph) have been synthesized and investigated both in solid and solution phase. Analytical and thermogravimetric data supported the general formula Alk(2)SnOHceph(.)H(2)O and Alk(3)Snceph(.)H(2)O (Alk=Me, n-Bu), while structural information has been gained by FT-IR, (119)Sn Mössbauer and (1)H, (13)C, (119)Sn NMR data. In particular, IR results suggested polymeric structures both for Alk(2)SnOHceph(.)H(2)O and Alk(3)Snceph(.)H(2)O. Moreover, cephalexin appears to behave as monoanionic tridentate ligand coordinating the tin(IV) atom through ester-type carboxylate, as well as through beta-lactam carbonyl oxygen atoms and the amino nitrogen donor atoms in Alk(2)SnOHceph(.)H(2)O complexes. On the basis of (119)Sn Mössbauer spectroscopy it could be inferred that tin(IV) was hexacoordinated in such complexes in the solid state, showing skew trapezoidal configuration. As far as Alk(3)Sn(IV)ceph(.)H(2)O derivatives are concerned, cephalexin coordinated the Alk(3)Sn moiety through the carboxylate acting as a bridging bidentate monoanionic group. Again, (119)Sn Mössbauer spectroscopy led us to propose a trigonal configuration around the tin(IV) atom, with R(3)Sn equatorial disposition and bridging carboxylate oxygen atoms in the axial positions. The nature of the complexes in solution state was investigated by using (1)H, (13)C and (119)Sn NMR spectroscopy. Finally, the cytotoxic activity of organotin(IV) cephalexinate derivatives has been tested using two different chromosome-staining techniques Giemsa and CMA(3), towards spermatocyte chromosomes of the mussel Brachidontes pharaonis (Mollusca: Bivalvia). Colchicinized-like mitoses (c-mitoses) on slides obtained from animals exposed to organotin(IV) cephalexinate compounds, demonstrated the high mitotic spindle-inhibiting potentiality of these chemicals

  5. VRA Modeling, phase 1

    NASA Technical Reports Server (NTRS)

    Kindt, Louis M.; Mullins, Michael E.; Hand, David W.; Kline, Andrew A.

    1995-01-01

    The destruction of organic contaminants in waste water for closed systems, such as that of Space Station, is crucial due to the need for recycling the waste water. A co-current upflow bubble column using oxygen as the gas phase oxidant and packed with catalyst particles consisting of a noble metal on an alumina substrate is being developed for this process. The objective of this study is to develop a plug-flow model that will predict the performance of this three phase reactor system in destroying a multicomponent mixture of organic contaminants in water. Mass balances on a series of contaminants and oxygen in both the liquid and gas phases are used to develop this model. These mass balances incorporate the gas-to-liquid and liquid-to-particle mass transfer coefficients, the catalyst effectiveness factor, and intrinsic reaction rate. To validate this model, a bench scale reactor has been tested at Michigan Technological University at elevated pressures (50-83 psig,) and a temperature range of 200 to 290 F. Feeds consisting of five dilute solutions of ethanol (approx. 10 ppm), chlorobenzene (approx. 20 ppb), formaldehyde (approx. 100 ppb), dimethyl sulfoxide (DMSO approx. 300 ppb), and urea (approx. 20 ppm) in water were tested individually with an oxygen mass flow rate of 0.009 lb/h. The results from these individual tests were used to develop the kinetic parameter inputs necessary for the computer model. The computer simulated results are compared to the experimental data obtained for all 5 components run in a mixture on the differential test column for a range of reactor contact times.

  6. FNAS phase partitions

    NASA Technical Reports Server (NTRS)

    Vanalstine, James M.

    1993-01-01

    Project NAS8-36955 D.O. #100 initially involved the following tasks: (1) evaluation of various coatings' ability to control wall wetting and surface zeta potential expression; (2) testing various methods to mix and control the demixing of phase systems; and (3) videomicroscopic investigation of cell partition. Three complementary areas were identified for modification and extension of the original contract. They were: (1) identification of new supports for column cell partition; (2) electrokinetic detection of protein adsorption; and (3) emulsion studies related to bioseparations.

  7. Athena: Assessment Phase Activities

    NASA Astrophysics Data System (ADS)

    Lumb, David; Ayre, Mark

    2015-09-01

    The Athena mission concept has been proposed by the community in response to science themes of the Hot and Energetic Universe. Unlike other, competitive, mission selection exercises this "Large" class observatory mission has essentially been pre-selected. Nevertheless it has to be demonstrated that Athena meets the programmatic constraints of 1Bn euro cost cap, and a readiness level appropriate for formal mission adoption by the end 2019. This should be confirmed through a Phase A study conducted with two parallel industry activities. We describe the technical and programmatic content of these and latest progress in space and ground segment definition.

  8. Phase retrieval using nonlinear diversity.

    PubMed

    Lu, Chien-Hung; Barsi, Christopher; Williams, Matthew O; Kutz, J Nathan; Fleischer, Jason W

    2013-04-01

    We extend the Gerchberg-Saxton algorithm to phase retrieval in a nonlinear system. Using a tunable photorefractive crystal, we experimentally demonstrate the noninterferometric technique by reconstructing an unknown phase object from optical intensity measurements taken at different nonlinear strengths.

  9. Microcellular foams via phase separation

    SciTech Connect

    Young, A.T.

    1985-01-01

    A study of wide variety of processes for making plastic foams shows that phase separation processes for polymers from solutions offers the most viable methods for obtaining rigid plastic foams which met the physical requirements for fusion target designs. Four general phase separation methods have been shown to give polymer foams with densities less than 0.1 g/cm/sup 3/ and cell sizes of 30..mu..m or less. These methods involve the utilization of non-solvent, chemical or thermal cooling processes to achieve a controlled phase separation wherein either two distinct phases are obtained where the polymer phase is a continuous phase or two bicontinuous phases are obtained where both the polymer and solvent are interpenetrating, continuous, labyrinthine phases. Subsequent removal of the solvent gives the final foam structure.

  10. Frequency discriminator/phase detector

    NASA Technical Reports Server (NTRS)

    Crow, R. B.

    1974-01-01

    Circuit provides dual function of frequency discriminator/phase detector which reduces frequency acquisition time without adding to circuit complexity. Both frequency discriminators, in evaluated frequency discriminator/phase detector circuits, are effective two decades above and below center frequency.

  11. NEWS: Phased by electricity?

    NASA Astrophysics Data System (ADS)

    2000-09-01

    Magnets and electricity are the topics of the latest issue of Phases published by the Education Department at the UK Institute of Physics. A simple but effective classroom activity shows how magnetic force can be used to measure the thickness of paint, and a worksheet explaining domestic electricity - wiring, plugs, fuses and how a light bulb works - is also featured. A list of resources (publications, courses, workshops, references and websites) complements the activities. Mailed free of charge to all schools in the UK and Ireland, each issue of this lively publication is designed to support the teaching of physics to 11-14 year-olds and covers a particular area of physics along with ideas for lessons and teacher resource information, as well as career information for pupils. In the case of this particular issue, however, it has been pointed out that fuses are used to protect wiring and not appliances. Please note this when using the activities provided with `Grandad's Chair'. If you have not received your copy of Phases, please contact the IOP Education Department (education_schools@iop.org).

  12. A cosmic superfluid phase

    NASA Technical Reports Server (NTRS)

    Gradwohl, Ben-Ami

    1991-01-01

    The universe may have undergone a superfluid-like phase during its evolution, resulting from the injection of nontopological charge into the spontaneously broken vacuum. In the presence of vortices this charge is identified with angular momentum. This leads to turbulent domains on the scale of the correlation length. By restoring the symmetry at low temperatures, the vortices dissociate and push the charges to the boundaries of these domains. The model can be scaled (phenomenologically) to very low energies, it can be incorporated in a late time phase transition and form large scale structure in the boundary layers of the correlation volumes. The novel feature of the model lies in the fact that the dark matter is endowed with coherent motion. The possibilities of identifying this flow around superfluid vortices with the observed large scale bulk motion is discussed. If this identification is possible, then the definite prediction can be made that a more extended map of peculiar velocities would have to reveal large scale circulations in the flow pattern.

  13. Reduction of phase artifacts in differential phase contrast computed tomography.

    PubMed

    Jerjen, Iwan; Revol, Vincent; Schuetz, Philipp; Kottler, Christian; Kaufmann, Rolf; Luethi, Thomas; Jefimovs, Konstantins; Urban, Claus; Sennhauser, Urs

    2011-07-01

    X-ray differential phase contrast computed tomography (DPC CT) with a Talbot-Lau interferometer setup allows visualizing the three-dimensional distribution of the refractive index by measuring the shifts of an interference pattern due to phase variations of the X-ray beam. Unfortunately, severe reconstruction artifacts appear in the presence of differential phase wrapping and clipping. In this paper, we propose to use the attenuation contrast, which is obtained from the same measurement, for correcting the DPC signal. Using the example of a DPC CT measurement with pronounced phase artifacts, we will discuss the efficiency of our phase artifact correction method. PMID:21747516

  14. Phase-coherent communications without explicit phase tracking.

    PubMed

    Song, H C; Hodgkiss, W S; van Walree, P A

    2010-09-01

    Phase-coherent communications typically requires a reliable phase-tracking algorithm. An initial phase estimate with training symbols allows a receiver to compensate for a motion-induced Doppler shift. Following the training period, however, explicit phase tracking can be avoided in time reversal communications that has been implemented on a block-by-block basis to accommodate time-varying channels. This is accomplished by a smaller block size and adaptive channel estimation using previously detected symbols on a symbol-by-symbol basis. The proposed time reversal approach without explicit phase tracking is demonstrated using experimental data (12-20 kHz) in shallow water.

  15. N-Consecutive-Phase Encoder

    NASA Technical Reports Server (NTRS)

    Divsalar, Dariush; Lee, Ho-Kyoung; Weber, Charles

    1995-01-01

    N-consecutive-phase encoder (NCPE) is conceptual encoder for generating alphabet of N consecutive full-response continuous-phase-modulation (CPM) signals. Enables use of binary preencoder of higher rate than used with simple continuous-phase encoder (CPE). NCPE makes possible to achieve power efficiencies and bandwidth efficiencies greater than conventional trellis coders with continuous-phase frequency-shift keying (CPFSK).

  16. Multiple phases of protien gels

    NASA Astrophysics Data System (ADS)

    Annaka, Masahiko; Tanaka, Toyoichi

    1994-03-01

    A multiple phase transition was observed in gels made by covalently cross-linking proteins in either native or denatured state. The enzymatic activity of the gels prepared from native α-chymotrypsin was determined for each of the multiple phases. The reversibility of the swelling degrees and the enzymatic reaction rates upon phase transition suggests that the protein is at a free energy minimum and thus in a phase.

  17. Phase calibration target for quantitative phase imaging with ptychography.

    PubMed

    Godden, T M; Muñiz-Piniella, A; Claverley, J D; Yacoot, A; Humphry, M J

    2016-04-01

    Quantitative phase imaging (QPI) utilizes refractive index and thickness variations that lead to optical phase shifts. This gives contrast to images of transparent objects. In quantitative biology, phase images are used to accurately segment cells and calculate properties such as dry mass, volume and proliferation rate. The fidelity of the measured phase shifts is of critical importance in this field. However to date, there has been no standardized method for characterizing the performance of phase imaging systems. Consequently, there is an increasing need for protocols to test the performance of phase imaging systems using well-defined phase calibration and resolution targets. In this work, we present a candidate for a standardized phase resolution target, and measurement protocol for the determination of the transfer of spatial frequencies, and sensitivity of a phase imaging system. The target has been carefully designed to contain well-defined depth variations over a broadband range of spatial frequencies. In order to demonstrate the utility of the target, we measure quantitative phase images on a ptychographic microscope, and compare the measured optical phase shifts with Atomic Force Microscopy (AFM) topography maps and surface profile measurements from coherence scanning interferometry. The results show that ptychography has fully quantitative nanometer sensitivity in optical path differences over a broadband range of spatial frequencies for feature sizes ranging from micrometers to hundreds of micrometers. PMID:27137054

  18. Phase detector for three-phase power factor controller

    NASA Technical Reports Server (NTRS)

    Nola, F. J. (Inventor)

    1984-01-01

    A phase detector for the three phase power factor controller (PFC) is described. The phase detector for each phase includes an operational amplifier which senses the current phase angle for that phase by sensing the voltage across the phase thyristor. Common mode rejection is achieved by providing positive feedback between the input and output of the voltage sensing operational amplifier. this feedback preferably comprises a resistor connected between the output and input of the operational amplifier. The novelty of the invention resides in providing positive feedback such that switching of the operational amplifier is synchronized with switching of the voltage across the thyristor. The invention provides a solution to problems associated with high common mode voltage and enables use of lower cost components than would be required by other approaches.

  19. Reflectarray for 120-GHz beam steering application: design, simulations, and measurements

    NASA Astrophysics Data System (ADS)

    Tamminen, Aleksi; Ala-Laurinaho, Juha; Gomes-Martins, David; Häkli, Janne; Koivisto, Päivi; Kärkkäinen, Mikko; Mäkelä, Sampo; Pursula, Pekka; Rantakari, Pekka; Sipilä, Markku; Säily, Jussi; Tuovinen, Reijo; Varonen, Mikko; Halonen, Kari A. I.; Luukanen, Arttu; Räisänen, Antti V.

    2012-06-01

    Development of a 120-GHz FMCW radar with a reflectarray as focusing element is described. The reflectarray is realized on a 150-mm silicon wafer and it has 3700 phase-modulating elements on it. The phase shifters have four discrete values to cover full phase modulation with 90° steps. The reflectarray element is realized with a conductor-backed coplanar waveguide patch antenna with a phase shifter coupled to it. The required phase modulation for each reflectarray element is determined with an in-house physical optics simulation combined with genetic-algorithm-based optimization. The reflectarrays are developed in two stages. First, preliminary reflectarrays with static phase shifters have been manufactured and tested at 120-GHz antenna measurement range. The static reflectarrays are found to perform as designed in their capability to steer the beam to a desired direction and to a distance of 3 m. The reflectarrays have -3-dB beam width from 1.1° to 1.3° depending on the beam tilt. After the preliminary verification with the static phase shifters, the reflectarrays will be assembled together with actively controlled MEMS-based phase shifters. The MEMS switches are controlled with dedicated high-voltage CMOS electronics, forming a system-in-a-package (SiP). First, the MEMS phase shifters are modeled, are being fabricated, and will be measured separately to verify their phase-shifting capability.

  20. Nature of the middle phase in three-phase micellar systems at phase behavior optimal salinity

    SciTech Connect

    Rosen, M.J.; Li, Z.P.

    1984-02-01

    Analysis of the middle phase of two heptane- surfactant-2-phenoxyethanol (cosurfactant)-brine systems at the point of phase behavior optimal salinity shows that surfactant and cosurfactant concentration gradients and a density gradient develop upon standing. Surfactant and cosurfactant concentrations and density all increase with depth below the upper (heptane/middle phase) interface. The nonhomogeneity depends upon the presence of condensed phases of different nature at both interfaces of the middle phase, as shown by its disappearance when the heptane phase is removed. The phenomenon is reversible, as shown by the reappearance of the gradients upon centrifugation of the middle phase, in the absence of heptane and brine phases, at sufficiently high speed. 16 references.

  1. Phase coexistence far from equilibrium

    NASA Astrophysics Data System (ADS)

    Dickman, Ronald

    2016-04-01

    Investigation of simple far-from-equilibrium systems exhibiting phase separation leads to the conclusion that phase coexistence is not well defined in this context. This is because the properties of the coexisting nonequilibrium systems depend on how they are placed in contact, as verified in the driven lattice gas with attractive interactions, and in the two-temperature lattice gas, under (a) weak global exchange between uniform systems, and (b) phase-separated (nonuniform) systems. Thus, far from equilibrium, the notions of universality of phase coexistence (i.e., independence of how systems exchange particles and/or energy), and of phases with intrinsic properties (independent of their environment) are lost.

  2. Phasing a segmented telescope

    NASA Astrophysics Data System (ADS)

    Paykin, Irina; Yacobi, Lee; Adler, Joan; Ribak, Erez N.

    2015-02-01

    A crucial part of segmented or multiple-aperture systems is control of the optical path difference between the segments or subapertures. In order to achieve optimal performance we have to phase subapertures to within a fraction of the wavelength, and this requires high accuracy of positioning for each subaperture. We present simulations and hardware realization of a simulated annealing algorithm in an active optical system with sparse segments. In order to align the optical system we applied the optimization algorithm to the image itself. The main advantage of this method over traditional correction methods is that wave-front-sensing hardware and software are no longer required, making the optical and mechanical system much simpler. The results of simulations and laboratory experiments demonstrate the ability of this optimization algorithm to correct both piston and tip-tilt errors.

  3. Phase equilibrium studies

    SciTech Connect

    Mathias, P.M.; Stein, F.P.

    1983-09-01

    A phase equilibrium model has been developed for the SRC-I process, as well as the other coal liquefaction processes. It is applicable to both vapor/liquid and liquid/liquid equilibria; it also provides an approximate but adequate description of aqueous mixtures where the volatile electrolyte components dissociate to form ionic species. This report completes the description of the model presented in an earlier report (Mathias and Stein, 1983a). Comparisons of the model to previously published data on coal-fluid mixtures are presented. Further, a preliminary analysis of new data on SRC-I coal fluids is presented. Finally, the current capabilities and deficiencies of the model are discussed. 25 references, 17 figures, 30 tables.

  4. Options Study - Phase II

    SciTech Connect

    R. Wigeland; T. Taiwo; M. Todosow; W. Halsey; J. Gehin

    2010-09-01

    The Options Study has been conducted for the purpose of evaluating the potential of alternative integrated nuclear fuel cycle options to favorably address the issues associated with a continuing or expanding use of nuclear power in the United States. The study produced information that can be used to inform decisions identifying potential directions for research and development on such fuel cycle options. An integrated nuclear fuel cycle option is defined in this study as including all aspects of the entire nuclear fuel cycle, from obtaining natural resources for fuel to the ultimate disposal of used nuclear fuel (UNF) or radioactive wastes. Issues such as nuclear waste management, especially the increasing inventory of used nuclear fuel, the current uncertainty about used fuel disposal, and the risk of nuclear weapons proliferation have contributed to the reluctance to expand the use of nuclear power, even though it is recognized that nuclear power is a safe and reliable method of producing electricity. In this Options Study, current, evolutionary, and revolutionary nuclear energy options were all considered, including the use of uranium and thorium, and both once-through and recycle approaches. Available information has been collected and reviewed in order to evaluate the ability of an option to clearly address the challenges associated with the current implementation and potential expansion of commercial nuclear power in the United States. This Options Study is a comprehensive consideration and review of fuel cycle and technology options, including those for disposal, and is not constrained by any limitations that may be imposed by economics, technical maturity, past policy, or speculated future conditions. This Phase II report is intended to be used in conjunction with the Phase I report, and much information in that report is not repeated here, although some information has been updated to reflect recent developments. The focus in this Options Study was to

  5. Multibeam Phased Array Antennas

    NASA Technical Reports Server (NTRS)

    Popovic, Zoya; Romisch, Stefania; Rondineau, Sebastien

    2004-01-01

    In this study, a new architecture for Ka-band multi-beam arrays was developed and demonstrated experimentally. The goal of the investigation was to demonstrate a new architecture that has the potential of reducing the cost as compared to standard expensive phased array technology. The goals of this specific part of the project, as stated in the yearly statement of work in the original proposal are: 1. Investigate bounds on performance of multi-beam lens arrays in terms of beamwidths, volume (size), isolation between beams, number of simultaneous beams, etc. 2. Design a small-scale array to demonstrate the principle. The array will be designed for operation around 3OGHz (Ka-band), with two 10-degree beamwidth beams. 3. Investigate most appropriate way to accomplish fine-tuning of the beam pointing within 5 degrees around the main beam pointing angle.

  6. METHODOLOGICAL NOTES: Metastable phases, phase transformations, and phase diagrams in physics and chemistry

    NASA Astrophysics Data System (ADS)

    Brazhkin, Vadim V.

    2006-07-01

    Concepts of a 'phase' and a 'phase transition' are discussed for stable and metastable states of matter. While condensed matter physics primarily considers equilibrium states and treats metastable phases as exceptions, organic chemistry overwhelmingly deals with metastable states. It is emphasized that many simple light-element compounds — including most hydrocarbons; nitrogen oxides, hydrides, and carbides; carbon monoxide CO; alcohols and glycerin — are also metastable at normal pressure in the sense that they do not correspond to a minimum Gibbs free energy for a given chemical composition. At moderate temperatures and pressures, the phase transformations for these metastable phases are reversible with the fulfilment of all laws of equilibrium thermodynamics over the entire range of experimentally accessible times. At sufficiently high pressures (> 1-10 GPa), most of the metastable molecular phases irreversibly transform to lower-energy polymer phases, stable or metastable. These transitions do not correspond to the equality of the Gibbs free energy for the involved phases before and after the transition and so they are not first-order in the 'classical' sense. At normal pressure, the resulting polymer phases can exist at temperatures above the melting point of the original metastable molecular phase, as the examples of polyethylene and polymerized CO dramatically illustrate. As pressure is increased further to 20-50 GPa, the PV contribution to Gibbs free energy gives rise to stable high-density atomic phases. Many of the intermediate-energy polymer phases can likely be synthesized by methods of 'classical' chemistry at normal pressure.

  7. Phase aberration effects in elastography.

    PubMed

    Varghese, T; Bilgen, M; Ophir, J

    2001-06-01

    In sonography, phase aberration plays a role in the corruption of sonograms. Phase aberration does not have a significant impact on elastography, if statistically similar phase errors are present in both the pre- and postcompression signals. However, if the phase errors are present in only one of the pre- or postcompression signal pairs, the precision of the strain estimation process will be reduced. In some cases, increased phase errors may occur only in the postcompression signal due to changes in the tissue structure with the applied compression. Phase-aberration effects increase with applied strain and may be viewed as an image quality derating factor, much like frequency-dependent attenuation or undesired lateral tissue motion. In this paper, we present a theoretical and simulation study of the effects of phase aberration on the elastographic strain-estimation process, using the strain filter approach.

  8. Time domain phase measuring apparatus

    NASA Technical Reports Server (NTRS)

    Reinhardt, V. S. (Inventor)

    1978-01-01

    The phase and/or period stability of a device is determined by connecting the device in one orthogonal arm of a phase detector having a mixer. In the other arm is an adjustable, variable phase shift device. The output of the mixer is fed through an active low pass filter to derive a DC voltage indicative of the phase shift. The variable phase device is adjusted so that the DC voltage will nullify the phase shift of the tested device under normal conditions. The DC voltage level is converted into a time interval indicative of the phase change of the tested device by determining when the level equals the amplitude of a low frequency ramp voltage. The interval between adjacent equality points can be measured or the period between a reference point on the ramp voltage and the quality be measured.

  9. Geometric phase in Bohmian mechanics

    SciTech Connect

    Chou, Chia-Chun; Wyatt, Robert E.

    2010-10-15

    Using the quantum kinematic approach of Mukunda and Simon, we propose a geometric phase in Bohmian mechanics. A reparametrization and gauge invariant geometric phase is derived along an arbitrary path in configuration space. The single valuedness of the wave function implies that the geometric phase along a path must be equal to an integer multiple of 2{pi}. The nonzero geometric phase indicates that we go through the branch cut of the action function from one Riemann sheet to another when we locally travel along the path. For stationary states, quantum vortices exhibiting the quantized circulation integral can be regarded as a manifestation of the geometric phase. The bound-state Aharonov-Bohm effect demonstrates that the geometric phase along a closed path contains not only the circulation integral term but also an additional term associated with the magnetic flux. In addition, it is shown that the geometric phase proposed previously from the ensemble theory is not gauge invariant.

  10. Development of Radar Control system for Multi-mode Active Phased Array Radar for atmospheric probing

    NASA Astrophysics Data System (ADS)

    Yasodha, Polisetti; Jayaraman, Achuthan; Thriveni, A.

    2016-07-01

    TR modules, (ii) radar operation software which facilitates experimental parameter setting and operating the radar in different modes, (iii) beam steering software which computes the amplitude co-efficients and phases required for each TR module, for forming the beams selected for radar operation with the desired shape and (iv) Calibration software for calibrating the radar by measuring the differential insertion phase and amplitudes in all 1024 Transmit and Receive paths and correcting them. The TR module configuring software is a major task as it needs to control 1024 TR modules, which are located in the field about 150 m away from the RC system in the control room. Each TR module has a processor identified with a dedicated IP address, along with memory to store the instructions and parameters required for radar operation. A communication link is designed using Gigabit Ethernet (GbE) switches to realise 1 to 1024 way switching network. RC system computer communicates with the each processor using its IP address and establishes connection, via 1 to 1024 port GbE switching network. The experimental parameters data are pre-loaded parallely into all the TR modules along with the phase shifter data required for beam steering using this network. A reference timing pulse is sent to all the TR modules simultaneously, which indicates the start of radar operation. RC system also monitors the status parameters from the TR modules indicating their health during radar operation at regular intervals, via GbE switching network. Beam steering software generates the phase shift required for each TR module for the beams selected for operation. Radar operational software calls the phase shift data required for beam steering and adds it to the calibration phase obtained through calibration software and loads the resultant phase data into TR modules. Timed command/data transfer to/from subsystems and synchronisation of subsystems is essential for proper real-time operation of the

  11. Development of Radar Control system for Multi-mode Active Phased Array Radar for atmospheric probing

    NASA Astrophysics Data System (ADS)

    Yasodha, Polisetti; Jayaraman, Achuthan; Thriveni, A.

    2016-07-01

    TR modules, (ii) radar operation software which facilitates experimental parameter setting and operating the radar in different modes, (iii) beam steering software which computes the amplitude co-efficients and phases required for each TR module, for forming the beams selected for radar operation with the desired shape and (iv) Calibration software for calibrating the radar by measuring the differential insertion phase and amplitudes in all 1024 Transmit and Receive paths and correcting them. The TR module configuring software is a major task as it needs to control 1024 TR modules, which are located in the field about 150 m away from the RC system in the control room. Each TR module has a processor identified with a dedicated IP address, along with memory to store the instructions and parameters required for radar operation. A communication link is designed using Gigabit Ethernet (GbE) switches to realise 1 to 1024 way switching network. RC system computer communicates with the each processor using its IP address and establishes connection, via 1 to 1024 port GbE switching network. The experimental parameters data are pre-loaded parallely into all the TR modules along with the phase shifter data required for beam steering using this network. A reference timing pulse is sent to all the TR modules simultaneously, which indicates the start of radar operation. RC system also monitors the status parameters from the TR modules indicating their health during radar operation at regular intervals, via GbE switching network. Beam steering software generates the phase shift required for each TR module for the beams selected for operation. Radar operational software calls the phase shift data required for beam steering and adds it to the calibration phase obtained through calibration software and loads the resultant phase data into TR modules. Timed command/data transfer to/from subsystems and synchronisation of subsystems is essential for proper real-time operation of the

  12. Phase comparison technique for measuring liquid-liquid phase equilibrium

    NASA Astrophysics Data System (ADS)

    Lu, Z.; Daridon, J. L.; Lagourette, B.; Ye, S.

    1999-04-01

    In this article, a new method is demonstrated to measure the liquid-liquid phase equilibrium for binary systems. A phase comparison technique was employed to real-time display the phase-time curve in a "wave form (time) object" of Hewlett-Packard visual engineering environment. It was found that the phase-time curve showed a distorted wave form when liquid-liquid phase transition took place. The abnormal curve can therefore be used to detect liquid-liquid phase transitions. Measurements were performed in several binary systems such as nitromethane+1-hexanol, nitromethane+butanol, and nitroethane+n-hexane. The experimental results are in good agreement with those in the literature.

  13. Phase computations and phase models for discrete molecular oscillators

    PubMed Central

    2012-01-01

    Background Biochemical oscillators perform crucial functions in cells, e.g., they set up circadian clocks. The dynamical behavior of oscillators is best described and analyzed in terms of the scalar quantity, phase. A rigorous and useful definition for phase is based on the so-called isochrons of oscillators. Phase computation techniques for continuous oscillators that are based on isochrons have been used for characterizing the behavior of various types of oscillators under the influence of perturbations such as noise. Results In this article, we extend the applicability of these phase computation methods to biochemical oscillators as discrete molecular systems, upon the information obtained from a continuous-state approximation of such oscillators. In particular, we describe techniques for computing the instantaneous phase of discrete, molecular oscillators for stochastic simulation algorithm generated sample paths. We comment on the accuracies and derive certain measures for assessing the feasibilities of the proposed phase computation methods. Phase computation experiments on the sample paths of well-known biological oscillators validate our analyses. Conclusions The impact of noise that arises from the discrete and random nature of the mechanisms that make up molecular oscillators can be characterized based on the phase computation techniques proposed in this article. The concept of isochrons is the natural choice upon which the phase notion of oscillators can be founded. The isochron-theoretic phase computation methods that we propose can be applied to discrete molecular oscillators of any dimension, provided that the oscillatory behavior observed in discrete-state does not vanish in a continuous-state approximation. Analysis of the full versatility of phase noise phenomena in molecular oscillators will be possible if a proper phase model theory is developed, without resorting to such approximations. PMID:22687330

  14. Simulation of Mission Phases

    NASA Technical Reports Server (NTRS)

    Carlstrom, Nicholas Mercury

    2016-01-01

    This position with the Simulation and Graphics Branch (ER7) at Johnson Space Center (JSC) provided an introduction to vehicle hardware, mission planning, and simulation design. ER7 supports engineering analysis and flight crew training by providing high-fidelity, real-time graphical simulations in the Systems Engineering Simulator (SES) lab. The primary project assigned by NASA mentor and SES lab manager, Meghan Daley, was to develop a graphical simulation of the rendezvous, proximity operations, and docking (RPOD) phases of flight. The simulation is to include a generic crew/cargo transportation vehicle and a target object in low-Earth orbit (LEO). Various capsule, winged, and lifting body vehicles as well as historical RPOD methods were evaluated during the project analysis phase. JSC core mission to support the International Space Station (ISS), Commercial Crew Program (CCP), and Human Space Flight (HSF) influenced the project specifications. The simulation is characterized as a 30 meter +V Bar and/or -R Bar approach to the target object's docking station. The ISS was selected as the target object and the international Low Impact Docking System (iLIDS) was selected as the docking mechanism. The location of the target object's docking station corresponds with the RPOD methods identified. The simulation design focuses on Guidance, Navigation, and Control (GNC) system architecture models with station keeping and telemetry data processing capabilities. The optical and inertial sensors, reaction control system thrusters, and the docking mechanism selected were based on CCP vehicle manufacturer's current and proposed technologies. A significant amount of independent study and tutorial completion was required for this project. Multiple primary source materials were accessed using the NASA Technical Report Server (NTRS) and reference textbooks were borrowed from the JSC Main Library and International Space Station Library. The Trick Simulation Environment and User

  15. Ion mixing and phase diagrams

    NASA Astrophysics Data System (ADS)

    Lau, S. S.; Liu, B. X.; Nicolet, M.-A.

    1983-05-01

    Interactions induced by ion irradiation are generally considered to be non-equilibrium processes, whereas phase diagrams are determined by phase equilibria. These two entities are seemingly unrelated. However, if one assumes that quasi-equilibrium conditions prevail after the prompt events, subsequent reactions are driven toward equilibrium by thermodynamical forces. Under this assumption, ion-induced reactions are related to equilibrium and therefore to phase diagrams. This relationship can be seen in the similarity that exists in thin films between reactions induced by ion irradiation and reactions induced by thermal annealing. In the latter case, phase diagrams have been used to predict the phase sequence of stable compound formation, notably so in cases of silicide formation. Ion-induced mixing not only can lead to stable compound formation, but also to metastable alloy formation. In some metal-metal systems, terminal solubilities can be greatly extended by ion mixing. In other cases, where the two constituents of the system have different crystal structures, extension of terminal solubility from both sides of the phase diagram eventually becomes structurally incompatible and a glassy (amorphous) mixture can form. The composition range where this bifurcation is likely to occur is in the two-phase regions of the phase diagram. These concepts are potentially useful guides in selecting metal pairs that from metallic glasses by ion mixing. In this report, phenomenological correlation between stable (and metastable) phase formation and phase diagram is discussed in terms of recent experimental data.

  16. Phase-shifting point diffraction interferometer phase grating designs

    DOEpatents

    Naulleau, Patrick

    2001-01-01

    Diffraction phase gratings are employed in phase-shifting point diffraction interferometers to improve the interferometric fringe contrast. The diffraction phase grating diffracts a zeroth-order diffraction of light at a first power level to the test-beam window of a mask that is positioned at the image plane and a first-order diffraction at a second power to the reference-beam pinhole. The diffraction phase grating is preferably selected to yield a desired ratio of the first power level to second power level.

  17. Topological phases and phase transitions on the honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Yang, Yuan; Li, Xiaobing; Xing, Dingyu

    2016-10-01

    We investigate possible phase transitions among the different topological insulators in a honeycomb lattice under the combined influence of spin-orbit couplings and staggered magnetic flux. We observe a series of topological phase transitions when tuning the flux amplitude, and find topologically nontrivial phases with high Chern number or spin-Chern number. Through tuning the exchange field, we also find a new quantum state which exhibits the electronic properties of both the quantum spin Hall state and quantum anomalous Hall state. The topological characterization based on the Chern number and the spin-Chern number are in good agreement with the edge-state picture of various topological phases.

  18. Optimal Phase Oscillatory Network

    NASA Astrophysics Data System (ADS)

    Follmann, Rosangela

    2013-03-01

    Important topics as preventive detection of epidemics, collective self-organization, information flow and systemic robustness in clusters are typical examples of processes that can be studied in the context of the theory of complex networks. It is an emerging theory in a field, which has recently attracted much interest, involving the synchronization of dynamical systems associated to nodes, or vertices, of the network. Studies have shown that synchronization in oscillatory networks depends not only on the individual dynamics of each element, but also on the combination of the topology of the connections as well as on the properties of the interactions of these elements. Moreover, the response of the network to small damages, caused at strategic points, can enhance the global performance of the whole network. In this presentation we explore an optimal phase oscillatory network altered by an additional term in the coupling function. The application to associative-memory network shows improvement on the correct information retrieval as well as increase of the storage capacity. The inclusion of some small deviations on the nodes, when solutions are attracted to a false state, results in additional enhancement of the performance of the associative-memory network. Supported by FAPESP - Sao Paulo Research Foundation, grant number 2012/12555-4

  19. Impulsive phase transport

    NASA Technical Reports Server (NTRS)

    Canfield, Richard C.; Bely-Dubau, Francoise; Brown, John C.; Dulk, George A.; Emslie, A. Gordon; Enome, Shinzo; Gabriel, Alan H.; Kundu, Mukul R.; Melrose, Donald; Neidig, Donald F.

    1986-01-01

    The transport of nonthermal electrons is explored. The thick-target electron beam model, in which electrons are presumed to be accelerated in the corona and typically thermalized primarily in the chromosphere and photosphere, is supported by observations throughout the electromagnetic spectrum. At the highest energies, the anisotropy of gamma-ray emission above 10 MeV clearly indicates that these photons are emitted by anisotropically-directed particles. The timing of this high-energy gamma-radiation with respect to lower-energy hard X-radiation implies that the energetic particles have short life-times. For collisional energy loss, this means that they are stopped in the chromosphere or below. Stereoscopic (two-spacecraft) observations at hard X-ray energies (up to 350 keV) imply that these lower-energy (but certainly nonthermal) electrons are also stopped deep in the chromosphere. Hard X-ray images show that, in spatially resolved flares whose radiation consists of impulsive bursts, the impulsive phase starts with X-radiation that comes mostly from the foot-points of coronal loops whose coronal component is outlined by microwaves.

  20. Phase change materials handbook

    NASA Technical Reports Server (NTRS)

    Hale, D. V.; Hoover, M. J.; Oneill, M. J.

    1971-01-01

    This handbook is intended to provide theory and data needed by the thermal design engineer to bridge the gap between research achievements and actual flight systems, within the limits of the current state of the art of phase change materials (PCM) technology. The relationship between PCM and more conventional thermal control techniques is described and numerous space and terrestrial applications of PCM are discussed. Material properties of the most promising PCMs are provided; the purposes and use of metallic filler materials in PCM composites are presented; and material compatibility considerations relevant to PCM design are included. The engineering considerations of PCM design are described, especially those pertaining to the thermodynamic and heat transfer phenomena peculiar to PCM design. Methods of obtaining data not currently available are presented. The special problems encountered in the space environment are described. Computational tools useful to the designer are discussed. In summary, each aspect of the PCM problem important to the design engineer is covered to the extent allowed by the scope of this effort and the state of the art.