Sample records for echelle grating spectrometer

  1. The Lick Observatory Hamilton Echelle Spectrometer

    Microsoft Academic Search

    Steven S. Vogt

    1987-01-01

    The Hamilton Echelle Spectrometer, installed at the coude focus of the Shane 3-m telescope, is a high-dispersion spectrograph optimized for use with today's largest available CCDs, and for the even larger CCDs expected in the future. It was designed primarily for high-resolution (R = 30,000 to 60,000) wide-bandpass spectroscopy of point-like sources down to a limiting magnitude of about V

  2. AIRES: an Airborne Infra-Red Echelle Spectrometer for SOFIA

    NASA Astrophysics Data System (ADS)

    Erickson, E. F.; Haas, M. R.; Colgan, S. W. J.; Roellig, T.; Simpson, J. P.; Telesco, C. M.; Pina, R. K.; Young, E. T.; Wolf, J.

    1997-12-01

    The Stratospheric Observatory for Infrared Astronomy, SOFIA, is a 2.7 meter telescope which is scheduled to begin observations in a Boeing 747 in October 2001. Among other SOFIA science instruments recently selected for development is the facility spectrometer AIRES. AIRES is designed for studies of a broad range of phenomena occuring in the interstellar medium (ISM) which are uniquely enabled by SOFIA. Examples include accretion and outflow in protostars and young stellar objects, the morphology, dynamics, and excitation of neutral and ionized gas at the Galactic center, and the recycling of material to the ISM from evolved stars. Astronomers using AIRES will be able to select any wavelength from 17 to 210 mu m., with corresponding spectral resolving powers ranging from 60,000 to 4000 in less than a minute. This entire wavelength range is important because it contains spectral features, often widely separated in wavelength, which characterize fundamental ISM processes. AIRES will utilize two-dimensional detector arrays and a large echelle grating to achieve spectral imaging with excellent sensitivity and unparalleled angular resolution at these wavelengths. As a facility science instrument, AIRES will provide guest investigators frequent opportunities for far infrared spectroscopic observations when SOFIA begins operations.

  3. Echelle crossed grating millimeter wave beam scanner.

    PubMed

    Furxhi, Orges; Marks, Daniel L; Brady, David J

    2014-06-30

    We present a two-dimensional, active, millimeter-wave, electronic beam scanner, with Doppler capabilities for stand-off imaging. The two-dimensional scan is achieved by mapping the millimeter wave spectrum to space using a pair of crossed gratings. The active transceiver and heterodyne quadrature detection allow the measurement of the relative phase between two consecutive measurements and the synthesis of the scene's Doppler signature. The frame rate of the imager is currently limited by the sweep rate of the vector network analyzer which is used to drive the millimeter wave extenders. All of the beam steering components are passive and can be designed to operate at any wavelength. The system design, characterization and measurements are presented and further uses and improvements are suggested. PMID:24977888

  4. First: Florida Ir Silicon Immersion Grating Spectrometer

    NASA Astrophysics Data System (ADS)

    Ge, Jian; Zhao, B.; Wang, J.; Wan, X.; Powell, S.

    2012-01-01

    The FIRST silicon immersion grating spectrometer is being developed at UF to search for habitable Earth-like planets around M dwarfs and giant planets around young active stars. This compact cryogenic IR instrument is designed to have a spectral resolution of R=72,000 at 1.4-1.8 µm with a silicon immersion grating and R=60K at 0.8-1.35 µm with an R4 echelle. The goal is to reach a long term Doppler precision of 1-3 m/s for bright M dwarfs. The FIRST silicon immersion grating, with 54.74 degree blaze angle and 16 l/mm groove density, has been fully characterized in the lab. The 50x50 mm square grating entrance pupil is coated with a single layer of anti-reflection coating resulting in a 2.1% measured reflection loss. The grating surface was coated with a gold layer to increase grating surface reflectivity. It has produced R=110,000 diffraction limited spectral resolution at 1.523 micron in a lab test spectrograph with 20 mm pupil diameter. The integrated scattered light is less than 0.2\\% and grating has no visible ghosts down to the measuring instrument noise level. The grating efficiency is 69\\% at the peak of the blaze. This silicon immersion grating is ready for scientific observations with FIRST. FIRST is scheduled to be integrated in the lab during the spring of 2012 and see the first light at an astronomical telescope (TBD) the summer of 2012.

  5. Echelle Gratings with Metal Reflectors in Generic Thick Silicon Technology

    E-print Network

    Doménech, José David; Muñoz, Pascual

    2015-01-01

    In this paper, the experimental demonstration of Echelle Grating multiplexers in generic thick Silicon technology, using metal reflectors, is reported. Two multiplexer designs are shown, covering the C-band and partially the S and L bands, with 4 and 8 channels respectively. The multiplexers exhibited performance similar to previously reported devices on dedicated manufacturing processes. The average figures measured are insertion loss 5 dB, loss non-uniformity 3 dB, polarization dependent loss 0.6 dB, polarization dependent wavelength shift of 0.3 nm, with reduced footprint. The performance comparison between multiplexers with and without metal mirrors, for both polarizations, is provided. Several dies were measured, and the passband features for the multiplexers are analyzed, giving a reference on the process variations for future designers.

  6. AIRES: An Airborne Infra-Red Echelle Spectrometer for SOFIA

    NASA Technical Reports Server (NTRS)

    Dotson, Jessie J.; Erickson, Edwin F.; Haas, Michael R.; Colgan, Sean W. J.; Simpson, Janet P.; Telesco, Charles M.; Pina, Robert K.; Wolf, Juergen; Young, Erick T.

    1999-01-01

    SOFIA will enable astronomical observations with unprecedented angular resolution at infrared wavelengths obscured from the ground. To help open this new chapter in the exploration of the infrared universe, we are building AIRES, an Airborne Infra-Red Echelle Spectrometer. AIRES will be operated as a first generation, general purpose facility instrument by USRA, NASA's prime contractor for SOFIA. AIRES is a long slit spectrograph operating from 17 - 210 microns. In high resolution mode the spectral resolving power is approx. 10(exp 6) microns/A or approx. 10(exp 4) at 100 microns. Unfortunately, since the conference, a low resolution mode with resolving power about 100 times lower has been deleted due to budgetary constraints. AIRES includes a slit viewing camera which operates in broad bands at 18 and 25 microns.

  7. Improvement of miniature grating spectrometers

    NASA Astrophysics Data System (ADS)

    Yang, Huaidong; Xu, Li; Chen, Kexin; Huang, Xingyue; He, Qingsheng; Jin, Guofan

    2008-03-01

    The trade-off between resolution and signal to noise ratio is a shackle to develop high performance miniature grating spectrometers. Concentrating on breaking this shackle, freeform optics and super-resolution restoration method for miniature grating spectrometers are proposed in this paper. Substituting a varying sagittal surface for a toroidal one, not only aberrations along dispersive direction can be reduced, but also aberrations perpendicular to dispersive direction can be reduced in a broad spectral range. This means both resolution and throughput would be multiplied. To reduce the remnant imperfection of system, subpixel-deconvolution process may be supplemented. By subpixel reconstruction, under-sampling due to finite pixel size of array detector would be got rid of. By deconvolution, blurring duo to slit and other system imperfection would be eliminated. Consequently, resolution and throughput would be further increased.

  8. Low-crosstalk fabrication-insensitive echelle grating multiplexers and passives for the silicon photonics toolbox

    NASA Astrophysics Data System (ADS)

    Sciancalepore, Corrado; Lycett, Richard J.; Dallery, Jacques A.; Pauliac, Sebastien; Hassan, Karim; Harduin, Julie; Duprez, Hélène; Weidenmueller, Ulf; Gallagher, Dominic F. G.; Menezo, Sylvie; Ben-Bakir, Badhise

    2015-02-01

    In this communication, we report about the design, fabrication, and testing of echelle grating (de-)multiplexers for the 100GBASE-LR4 norm and other passive architectures such as vertical fiber-couplers and slow-wave waveguides in the O-band (1.31-?m) for Silicon-based photonic integrated circuits (Si-PICs). In detail, two-point stigmatic 20th-order echelle gratings (TPSGs) on the 300-nm-thick SOI platform designed for 4x800-GHz-spaced wavelength division multiplexing featuring extremely low crosstalk (< -30 dB), precise channel spacing and optimized average insertion losses (~ 3 dB) are presented. Distributed Bragg reflectors (DBRs) are used to improve the grating facets reflectivity, while multi-mode interferometers (MMIs) are used in optimized perfectly-chirped echelle gratings (PCGs) for pass-band flattening. Moreover, 200-mm CMOS pilot lines processing tools including VISTEC variable-shape e-beam lithography are employed for the fabrication. In addition, wafer-level statistics of the multiplexers clearly shows the echelle grating to be inherently fabrication-insensitive to processing drifts, resulting in a minimized dispersion of the multiplexer performances over the wafer. In particular, the echelle grating spectral response remains stable over the wafer in terms of crosstalk, channel spacing and bandwidth, with the wavelength dispersion of the filter comb being limited to just 0.8 nm, thus highlighting the intrinsic robustness of design, fab pathways as well as the reliability of modeling tools. As well as that, apodized one-dimensional vertical fiber couplers, optimized multi-mode interferometers (MMIs) and extremely low-losses slow-light waveguides are demonstrated and discussed. The adiabatic apodization of such 1-D gratings is capable to provide band-edge group indices ng as high as 30 with propagation losses equivalent to the indexlike propagation regime.

  9. Testing of an Echelle Spectrometer as a LIBS Detector at Sandia

    SciTech Connect

    David P. Baldwin; Daniel S. Zamzow; David K. Ottesen; Howard A. Johnsen

    2001-04-25

    Some useful information has been obtained regarding the potential use of the echelle spectrometer system for Laser-Induced Breakdown Spectroscopy (LIBS) monitoring applications, despite the AOTF-computer operational problems during the Sandia site-test. Currently, the use of the echelle spectrometer with the LIBS system is not suitable for trace-level analyte detection. This is due, in part, to the lower light throughput of the echelle spectrometer system compared to the SpectraPro-275. The low duty cycle of the LIBS system, which results from the use of a low-repetition-rate (but low-cost and portable) laser, also limits the detection sensitivity achievable using a high-resolution spectrometer. At high analyte concentrations, the echelle spectrometer is able to resolve spectral interferences including the Cd-As line pair at 228.8-nm and other LIBS emission features not resolved using the SpectraPro-275. A definite positive result obtained is the determination that at the high resolution of the echelle spectrometer, time-gating of the CCD detector is not necessary to discriminate analyte spectral signals from the LIBS background emission. The cost of the gated CCD and associated electronics is a significant portion of the cost of the Sandia LIBS system. Incorporation of a low-cost version of the echelle spectrometer for process monitoring applications not requiring trace-level detection could make LIBS a more viable technique where cost is a limiting factor. We hope to have the opportunity to perform additional collaborative work using the AOTF-echelle spectrometer for on-line LIBS monitoring applications, in order to demonstrate the advantage of rapid line-switching (using the AOTF) and simultaneous detection of multiple emission features across the spectral range of the echelle.

  10. Imaging Spectrometers Using Concave Holographic Gratings

    NASA Technical Reports Server (NTRS)

    Gradie, J.; Wang, S.

    1993-01-01

    Imaging spectroscopy combines the spatial attributes of imaging with the compositionally diagnostic attributes of spectroscopy. For spacebased remote sensing applications, mass, size, power, data rate, and application constrain the scanning approach. For the first three approaches, substantial savings in mass and size of the spectrometer can be achieved in some cases with a concave holographic grating and careful placement of an order-sorting filter. A hologram etched on the single concave surface contains the equivalent of the collimating, dispersing, and camera optics of a conventional grating spectrometer and provides substantial wavelength dependent corrections for spherical aberrations and a flat focal field. These gratings can be blazed to improve efficiency when used over a small wavelength range or left unblazed for broadband uniform efficiency when used over a wavelength range of up to 2 orders. More than 1 order can be imaged along the dispersion axis by placing an appropriately designed step order-sorting filter in front of the one- or two-dimensional detector. This filter can be shaped for additional aberration corrections. The VIRIS imaging spectrometer based on the broadband design provides simultaneous imaging of the entrance slit from lambda = 0.9 to 2.6 microns (1.5 orders) onto a 128 x 128 HgCdTe detector (at 77 K). The VIRIS spectrometer was used for lunar mapping with the UH 24.in telescope at Mauna Kea Observatory. The design is adaptable for small, low mass, space based imaging spectrometers.

  11. CFHT f/4 coude echelle spectrograph, 316 g/mm 30 CM mosaic grating

    NASA Astrophysics Data System (ADS)

    Grundmann, W. A.; Moore, F. A.; Richardson, E. H.

    1990-07-01

    The optical design of an f/4 coude echelle spectrograph for the 3.6-m Canada-France-Hawaii Telescope is described and illustrated with drawings and diagrams. The basic configuration comprises a tilted spherical f/20 collimator mirror, a 30-cm 316-g/mm grating near the slit, a paraboloid camera mirror, and a small triplet corrector lens. Two sets of optics are provided, coated for optimal performance in the UV-blue and green-IR regions, respectively, and small remotely selectable variable-wedge grism or grens modules are located in the diverging beam from the slit to the collimator to prevent other orders from overlapping the part of the spectrum being recorded. Consideration is given to the Hartmann mask system, the mosaic grating controls, the collimator and camera mirror turrets, and the detector support.

  12. Spectrometer system using a modular echelle spectrograph and a laser-driven continuum source for simultaneous multi-element determination by graphite furnace absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Geisler, Sebastian; Okruss, Michael; Becker-Ross, Helmut; Huang, Mao Dong; Esser, Norbert; Florek, Stefan

    2015-05-01

    A multi-element absorption spectrometer system has been developed based on a laser-driven xenon continuum source and a modular simultaneous echelle spectrograph (MOSES), which is characterized by a minimized number of optical components resulting in high optical throughput, high transmittance and high image quality. The main feature of the new optical design is the multifunction usage of a Littrow prism, which is attached on a rotation stage. It operates as an order-sorter for the echelle grating in a double-pass mode, as a fine positioning device moving the echelle spectrum on the detector, and as a forwarder to address different optical components, e.g., echelle gratings, in the setup. Using different prisms, which are mounted back to back on the rotation stage, a multitude of different spectroscopic modes like broad-range panorama observations, specific UV-VIS and NIR studies or high resolution zoom investigations of variable spectral channels can be realized. In the UV panorama mode applied in this work, MOSES has simultaneously detectable wavelength coverage from 193 nm to 390 nm with a spectral resolution ?/?? of 55,000 (3-pixel criterion). In the zoom mode the latter can be further increased by a factor of about two for a selectable section of the full wavelength range. The applicability and the analytical performance of the system were tested by simultaneous element determination in a graphite furnace, using eight different elements. Compared to an instrument operating in the optimized single line mode, the achieved analytical sensitivity using the panorama mode was typically a factor of two lower. Using the zoom mode for selected elements, comparable sensitivities were obtained. The results confirm the influence of the different spectral resolutions.

  13. A transmission grating spectrometer for plasma diagnostics

    SciTech Connect

    Bartlett, R.J.; Hockaday, R.G. [Los Alamos National Lab., NM (United States); Gallegos, C.H.; Gonzales, J.M.; Mitton, V. [EG and G Energy Measurements, Los Alamos, NM (United States)

    1995-09-01

    Radiation temperature is an important parameter in characterizing the properties of hot plasmas. In most cases this temperature is time varying caused by the short lived and/or time dependent nature of the plasma. Thus, a measurement of the radiation flux as a function of time is quite valuable. To this end the authors have developed a spectrometer that can acquire spectra with a time resolution of less than 1 ns and covers the spectral energy range from {approximately} 60 to 1,000 eV. The spectrometer consists of an entrance slit placed relatively near the plasma, a thin gold film transmission grating with aperture, a micro channel plate (MCP) detector with a gold cathode placed at the dispersion plane and an electron lens to focus the electrons from the MCP onto a phosphor coated fiber optic plug. The phosphor (In:CdS) has a response time of {approximately} 500 ps. This detector system, including the fast phosphor is similar to one that has been previously described. The spectrometer is in a vacuum chamber that is turbo pumped to a base pressure of {approximately} 5 x 10{sup 7} torr. The light from the phosphor is coupled to two streak cameras through 100 m long fiber optic cables. The streak cameras with their CCD readouts provide the time resolution of the spectrum. The spectrometer has a built in alignment system that uses an alignment telescope and retractable prism.

  14. Linear Fresnel Spectrometer Chip with Gradient Line Grating

    NASA Technical Reports Server (NTRS)

    Choi, Sang Hyouk (Inventor); Park, Yeonjoon (Inventor)

    2015-01-01

    A spectrometer that includes a grating that disperses light via Fresnel diffraction according to wavelength onto a sensing area that coincides with an optical axis plane of the grating. The sensing area detects the dispersed light and measures the light intensity associated with each wavelength of the light. Because the spectrometer utilizes Fresnel diffraction, it can be miniaturized and packaged as an integrated circuit.

  15. Immersion echelle spectrograph

    DOEpatents

    Stevens, Charles G. (Danville, CA); Thomas, Norman L. (Livermore, CA)

    2000-01-01

    A small spectrograph containing no moving components and capable of providing high resolution spectra of the mid-infrared region from 2 microns to 4 microns in wavelength. The resolving power of the spectrograph exceeds 20,000 throughout this region and at an optical throughput of about 10.sup.-5 cm.sup.2 sr. The spectrograph incorporates a silicon immersion echelle grating operating in high spectral order combined with a first order transmission grating in a cross-dispersing configuration to provide a two-dimensional (2-D) spectral format that is focused onto a two-dimensional infrared detector array. The spectrometer incorporates a common collimating and condensing lens assembly in a near aberration-free axially symmetric design. The spectrometer has wide use potential in addition to general research, such as monitoring atmospheric constituents for air quality, climate change, global warming, as well as monitoring exhaust fumes for smog sources or exhaust plumes for evidence of illicit drug manufacture.

  16. Spectral calibration for convex grating imaging spectrometer

    NASA Astrophysics Data System (ADS)

    Zhou, Jiankang; Chen, Xinhua; Ji, Yiqun; Chen, Yuheng; Shen, Weimin

    2013-12-01

    Spectral calibration of imaging spectrometer plays an important role for acquiring target accurate spectrum. There are two spectral calibration types in essence, the wavelength scanning and characteristic line sampling. Only the calibrated pixel is used for the wavelength scanning methods and he spectral response function (SRF) is constructed by the calibrated pixel itself. The different wavelength can be generated by the monochromator. The SRF is constructed by adjacent pixels of the calibrated one for the characteristic line sampling methods. And the pixels are illuminated by the narrow spectrum line and the center wavelength of the spectral line is exactly known. The calibration result comes from scanning method is precise, but it takes much time and data to deal with. The wavelength scanning method cannot be used in field or space environment. The characteristic line sampling method is simple, but the calibration precision is not easy to confirm. The standard spectroscopic lamp is used to calibrate our manufactured convex grating imaging spectrometer which has Offner concentric structure and can supply high resolution and uniform spectral signal. Gaussian fitting algorithm is used to determine the center position and the Full-Width-Half-Maximum?FWHM?of the characteristic spectrum line. The central wavelengths and FWHMs of spectral pixels are calibrated by cubic polynomial fitting. By setting a fitting error thresh hold and abandoning the maximum deviation point, an optimization calculation is achieved. The integrated calibration experiment equipment for spectral calibration is developed to enhance calibration efficiency. The spectral calibration result comes from spectral lamp method are verified by monochromator wavelength scanning calibration technique. The result shows that spectral calibration uncertainty of FWHM and center wavelength are both less than 0.08nm, or 5.2% of spectral FWHM.

  17. Observation of laser feedback using a grating spectrometer

    NASA Astrophysics Data System (ADS)

    Brekke, Erik G.; Schulz, Matthew A.

    2015-07-01

    We describe an experimental setup for observing the effect of optical feedback in an extended cavity diode laser. A simple grating spectrometer is used to observe the naturally occurring wavelength spread and mode spacing for the diode. When the diode is provided with optical feedback from a grating in the Littman-Metcalf configuration, the tunability of the diode is easily observed. This setup presents an intuitive and cost-effective method for demonstrating optical feedback in an advanced undergraduate laboratory setting.

  18. System design of multi-function grating spectrometer

    NASA Astrophysics Data System (ADS)

    Sui, Cheng-hua; Xu, Dan-yang; Tong, Jian-ping; Yang, Yang

    2010-10-01

    A multi-function grating spectrometer is introduced, which is composed of grating monochromator, signal receiving units, electronic amplifiers, A/D converter, computer, matching illuminant and so on. This equipment is a complex technique related to optics, precision machinery, electronics and computer. CCD and optical grating is used that break the limitation of photomultiplier (PMT). The CCD can receive signals in the spatial distribution. The efficiency of full spectrum detection is greatly raised. With the way of DMA block move and adopting high-speed A/D AD1674JN it realizes high-speed data acquisition. The principles of system working, hardware circuit, logic of controlling are described in detail. The spectrometer has two kinds of measurement range, the CCD can measure the spectrum wave from 300 nm~600 nm, and the photomultiplier (PMT) can measure the spectrum wave from 200 nm~660 nm. Controlling a Step Motor that cooperating with a deceleration system, and using the C-T optical system, in theory, moving 0.01 nm can catch a spectral pulse, the resolution can reach 0.06 nm.

  19. The Reflection Grating Spectrometer on Board XMM-Newton

    NASA Technical Reports Server (NTRS)

    denHerder, J. W.; Brinkman, A. C.; Kahn, S. M.; Branduardi-Raymont, G.; Thomsen, K.; Aarts, H.; Audard, M.; Bixler, J. V.; denBoggende, A. J.

    2000-01-01

    The ESA X-ray Multi Mirror mission, XMM-Newton, carries two identical Reflection Grating Spectrometers (RGS) behind two of its three nested sets of Wolter I type mirrors. The instrument allows high-resolution (E/(Delta)E = 100 to 500) measurements in the soft X-ray range (6 to 38 A or 2.1 to 0.3 keV) with a maximum effective area of about 140 sq cm at 15 A. Its design is optimized for the detection of the K-shell transitions of carbon, nitrogen, oxygen, neon, magnesium, and silicon. as well as the L shell transitions of iron. The present paper gives a full description of the design of the RGS and its operational modes. We also review details of the calibrations and in-orbit performance including the line spread function, the wavelength calibration, the effective area, and the instrumental background.

  20. A simple scanning spectrometer based on a stretchable elastomeric reflective grating

    SciTech Connect

    Ghisleri, C.; Milani, P., E-mail: paolo.milani@mi.infn.it [CIMAINA and Dipartimento di Fisica, Università di Milano, via Celoria 16, 20133 Milano (Italy); WISE srl, Piazza Duse 2, 20122 Milano (Italy); Potenza, M. A. C.; Bellacicca, A. [CIMAINA and Dipartimento di Fisica, Università di Milano, via Celoria 16, 20133 Milano (Italy); Ravagnan, L. [WISE srl, Piazza Duse 2, 20122 Milano (Italy)

    2014-02-10

    We report a scanning optical spectrometer based on the use of a stretchable elastomeric reflective grating. The grating is obtained by supersonic cluster beam implantation of silver nanoparticles on polydimethylsiloxane previously grooved by molding to create a replica of a commercial digital versatile disk grating. The use of a stretchable grating allows the spectrometer spanning the whole optical wavelength range by solely extending the diffraction element by more than 100% of its original dimensions. The stretchable reflective optical grating shows excellent performances and stability upon thousands of stretching cycles. The use of this elastomeric element makes the optical layout and the mechanics of the spectrometer extremely simple and advantageous for those applications where spectral resolution is not a major requirement. As a proof of principle, we present the absorption spectrum of Rhodamine B in solution obtained by our spectrometer and compared to commercial instruments.

  1. All-aluminum optical system for a large cryogenically cooled far infrared echelle spectrometer

    NASA Technical Reports Server (NTRS)

    Erickson, E. F.; Augason, G. C.; Houck, J. R.; Harwit, M. O.; Rank, D. M.

    1985-01-01

    In the past few years, NASA's Kuiper Airborne Observatory (KAO) has made it possible to conduct pioneering observations of far infrared lines from astronomical sources. Such observations, in the case of wavelengths in the approximate range from 20 to 350 microns, cannot be performed from ground-based sites, because of telluric water absorption effects. Lines in the considered range provide information about the interstellar gas in molecular, neutral atomic, and ionized form of occurrence. The present paper provides a description of the development of the cryogenic optical system of a spectrometer designed to exploit the potential of the KAO for observing the far infrared lines. Attention is given to design goals and considerations, details of optical design, the fabrication of the optical system, the cryostat, and performance.

  2. Development of a critical-angle transmission grating spectrometer for the International X-Ray Observatory

    E-print Network

    Smith, Matthew

    We present a high-resolution soft x-ray grating spectrometer concept for the International X-Ray Observatory (IXO) that meets or exceeds the minimum requirements for effective area (> 1, 000 cm[superscript 2] for E < 1 ...

  3. Soft X-Ray Critical-Angle Transmission Grating Spectrometer for the International X-Ray Observatory

    Microsoft Academic Search

    Ralf K. Heilmann; M. Ahn; K. A. Flanagan; D. P. Huenemoerder; M. L. Schattenburg

    2009-01-01

    We have developed a new type of soft x-ray diffraction grating. This critical-angle transmission (CAT) grating [1-4] combines the advantages of traditional transmission gratings (very low mass, extremely relaxed alignment and flatness tolerances) with those of x-ray reflection gratings (high efficiency due to blazing in the direction of grazing-incidence reflection). In addition, grating spectrometers based on CAT gratings are well-suited

  4. Passive Spectroscopy Bolometers, Grating- And X-Ray Imaging Crystal Spectrometers

    SciTech Connect

    Bitter, M; Hill, K W; Scott, S; Paul, S; Ince-Cushmann, A; Reinke, M; Rice, J; Beiersdorfer, P; Gu, M F; Lee, S G; Broennimann, C; Eikenberry, E F

    2007-11-07

    This tutorial gives a brief introduction into passive spectroscopy and describes the working principles of bolometers, a high-resolution grating spectrometer, and a novel X-ray imaging crystal spectrometer, which is of particular interest for profile measurements of the ion temperature and plasma rotation velocity on ITER and future burning plasma experiments.

  5. JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 31, NO. 13, JULY 1, 2013 2099 Echelle Diffractive Grating Based Wavelength

    E-print Network

    Yao, Jianping

    (SHM). Fiber Bragg grating (FBG) sensors have demonstrated great potential in both. But the currently available interrogation systems can only handle one of the two types of SHM capabilities offered by FBG sensors. In addition, the practical implementation of FBG sensor systems in aerospace vehicles requires

  6. A filter free dual transmission grating spectrometer for the extreme-ultraviolet

    Microsoft Academic Search

    Seth R. Wieman; Leonid V. Didkovsky; Darrell L. Judge; Andrew R. Jones; Matthew Harmon

    2007-01-01

    We report the design and laboratory testing of a prototype dual-grating filter-free extreme ultraviolet (EUV) spectrometer that has potential as a highly stable instrument for measuring absolute solar irradiance in the X-ray through far ultraviolet spectral range. The instrument is based on the same freestanding transmission gratings and silicon photodiodes used on the successful Solar EUV Monitor (SEM) aboard SOHO

  7. A filter free dual transmission grating spectrometer for the extreme- ultraviolet

    Microsoft Academic Search

    Seth R. Wieman; Leonid V. Didkovsky; Darrell L. Judge; Andrew R. Jones; Matthew Harmon

    We report the design and laboratory testing of a prototype dual-grating filter-free extreme ultraviolet (EUV) spectrometer that has potential as a highly stable instrument for measuring absolute solar irradiance in the X-ray through far ultraviolet spectral range. The instrument is based on the same freestanding transmission gratings and silicon photodiodes used on the successful Solar EUV Monitor (SEM) aboard SOHO

  8. Development of immersed diffraction grating for the TROPOMI-SWIR spectrometer

    NASA Astrophysics Data System (ADS)

    van Amerongen, A. H.; Visser, H.; Vink, R. J. P.; Coppens, T.; Hoogeveen, R. W. M.

    2010-10-01

    We have developed a novel diffraction grating based on lithographical techniques and anisotropic etching in silicon. The grating is designed for the short-wave-infrared channel of the TROPOMI imaging spectrometer that will be launched on ESA's Sentinel 5 Precursor mission to monitor trace gases in the earth atmosphere. Stringent requirements on both the imaging properties and the quality of the spectra translate to a high-tech grating. In our design the dispersion and resolution is increased with a factor 3.4 with respect to conventional gratings by using the grating in immersion, such that diffraction takes place inside the silicon grating material. By lithographic patterning and anisotropic etching of the mono-crystalline silicon we precisely control line spacing and blaze angle. The grating has a line spacing of 2.5 ?m and is operated in sixth order. We show that an efficiency of 60% is reached on a 50 x 60 mm2 grating surface. We compare our test results with numerical calculations for grating efficiency for both polarizations and find good agreement.

  9. High-Energy Transmission Grating Spectrometer for the Advanced X-ray Astrophysics Facility (AXAF)

    Microsoft Academic Search

    Thomas H. Markert; Claude R. Canizares; Daniel Dewey; Michael McGuirk; Chris S. Pak; Mark L. Schattenburg

    1994-01-01

    The High Energy Transmission Grating Spectrometer (HETGS) is one of the scientific instruments being developed for NASA's Advanced X-ray Astrophysics Facility (AXAF), scheduled for launch in 1998. The HETGS will be capable of measuring spectra with high resolution and sensitivity from a variety of compact and slightly extended cosmic X-ray sources. In this paper we describe the overall design of

  10. Portable NIR/MIR Fourier-transform spectrometer based on a common path lamellar grating interferometer

    NASA Astrophysics Data System (ADS)

    Merenda, F.; Bühler, S.; Farah, H.; Boer, G.; Scharf, T.

    2010-04-01

    We present a recently developed miniature scanning Fourier-Transform spectrometer (ARCspectro ANIR), which is based on a lamellar grating interferometer and uses a micro-mechanical actuator. The small dimensions of the interferometer (35 mm x 35 mm x 65 mm) and its low weight makes this device a truly portable Fourier-Transform spectrometer. Two different versions of this new spectrometer are presented: one version uses an InGaAs photodiode (0.9?m to 2.6 ?m) and the other a MCT detector (2 to 4.5 ?m). Their performances are discussed and also illustrated with measurement and application examples.

  11. Design and fabrication of an active polynomial grating for soft-X-ray monochromators and spectrometers

    NASA Astrophysics Data System (ADS)

    Chen, S.-J.; Chen, C. T.; Perng, S. Y.; Kuan, C. K.; Tseng, T. C.; Wang, D. J.

    2001-07-01

    An active polynomial grating has been designed for use in synchrotron radiation soft-X-ray monochromators and spectrometers. The grating can be dynamically adjusted to obtain the third-order-polynomial surface needed to eliminate the defocus and coma aberrations at any photon energy. Ray-tracing results confirm that a monochromator or spectrometer based on this active grating has nearly no aberration limit to the overall spectral resolution in the entire soft-X-ray region. The grating substrate is made of a precisely milled 17-4 PH stainless steel parallel plate, which is joined to a flexure-hinge bender shaped by wire electrical discharge machining. The substrate is grounded into a concave cylindrical shape with a nominal radius and then polished to achieve a roughness of 0.45 nm and a slope error of 1.2 ?rad rms. The long trace profiler measurements show that the active grating can reach the desired third-order polynomial with a high degree of figure accuracy.

  12. A filter free dual transmission grating spectrometer for the extreme-ultraviolet

    NASA Astrophysics Data System (ADS)

    Wieman, Seth R.; Didkovsky, Leonid V.; Judge, Darrell L.; Jones, Andrew R.; Harmon, Matthew

    2007-09-01

    We report the design and laboratory testing of a prototype dual-grating filter-free extreme ultraviolet (EUV) spectrometer that has potential as a highly stable instrument for measuring absolute solar irradiance in the X-ray through far ultraviolet spectral range. The instrument is based on the same freestanding transmission gratings and silicon photodiodes used on the successful Solar EUV Monitor (SEM) aboard SOHO and the EUV Spectrophotometer (ESP) part of the EVE instrument suite to be flown on SDO. Its two gratings, placed in series, along with a simple baffle structure provide excellent out of band "white" light rejection. Because the instrument does not use any thin film filters or reflective optics it is not susceptible to the degradation and instability associated with such optical elements. We present photometric efficiency data from laboratory tests with a Helium and Hydrogen discharge light source and measurements of "white" light rejection taken using the Mt Wilson Observatory 60' solar telescope.

  13. An infrared high resolution silicon immersion grating spectrometer for airborne and space missions

    NASA Astrophysics Data System (ADS)

    Ge, Jian; Zhao, Bo; Powell, Scott; Jiang, Peng; Uzakbaiuly, Berik; Tanner, David

    2014-08-01

    Broad-band infrared (IR) spectroscopy, especially at high spectral resolution, is a largely unexplored area for the far IR (FIR) and submm wavelength region due to the lack of proper grating technology to produce high resolution within the very constrained volume and weight required for space mission instruments. High resolution FIR spectroscopy is an essential tool to resolve many atomic and molecular lines to measure physical and chemical conditions and processes in the environments where galaxy, star and planets form. A silicon immersion grating (SIG), due to its over three times high dispersion over a traditional reflective grating, offers a compact and low cost design of new generation IR high resolution spectrographs for space missions. A prototype SIG high resolution spectrograph, called Florida IR Silicon immersion grating spectromeTer (FIRST), has been developed at UF and was commissioned at a 2 meter robotic telescope at Fairborn Observatory in Arizona. The SIG with 54.74 degree blaze angle, 16.1 l/mm groove density, and 50x86 mm2 grating area has produced R=50,000 in FIRST. The 1.4-1.8 um wavelength region is completely covered in a single exposure with a 2kx2k H2RG IR array. The on-sky performance meets the science requirements for ground-based high resolution spectroscopy. Further studies show that this kind of SIG spectrometer with an airborne 2m class telescope such as SOFIA can offer highly sensitive spectroscopy with R~20,000-30,000 at 20 to 55 microns. Details about the on-sky measurement performance of the FIRST prototype SIG spectrometer and its predicted performance with the SOFIA 2.4m telescope are introduced.

  14. A Near-Infrared Spectrometer Based on Novel Grating Light Modulators

    PubMed Central

    Wei, Wei; Huang, Shanglian; Wang, Ning; Jin, Zhu; Zhang, Jie; Chen, Weimin

    2009-01-01

    A near-infrared spectrometer based on novel MOEMS grating light modulators is proposed. The spectrum detection method that combines a grating light modulator array with a single near-infrared detector has been applied. Firstly, optics theory has been used to analyze the essential principles of the proposed spectroscopic sensor. Secondly, the grating light modulators have been designed and fabricated by micro-machining technology. Finally, the principles of this spectroscopic sensor have been validated and its key parameters have been tested by experiments. The result shows that the spectral resolution is better than 10 nm, the wavelength deviation is less than 1 nm, the deviation of the intensity of peak wavelength is no more than 0.5%, the driving voltage of grating light modulators array device is below 25 V and the response frequency of it is about 5 kHz. With low cost, satisfactory precision, portability and other advantages, the spectrometer should find potential applications in food safety and quality monitoring, pharmaceutical identification and agriculture product quality classification. PMID:22574065

  15. Advanced statistical analysis of laser-induced breakdown spectroscopy data to discriminate sedimentary rocks based on Czerny-Turner and Echelle spectrometers

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaoqin; Xu, Tao; Lin, Qingyu; Liang, Long; Niu, Guanghui; Lai, Hongjun; Xu, Mingjun; Wang, Xu; Li, Hua; Duan, Yixiang

    The correct identification of rock types is critical for understanding the origins and history of any particular rock body. Laser-induced breakdown spectroscopy (LIBS) has developed into an excellent analytical tool for geological materials research because of its numerous technical advantages compared with traditional methods. The coupling of LIBS with advanced multivariate analysis has received increasing attention because it facilitates the rapid processing of spectral information to differentiate and classify samples. In this study, we collected LIBS datasets for 16 sedimentary rocks from Triassic strata in Sichuan Basin. We compared the performance of two types of spectrometers (Czerny-Turner and Echelle) for classification of rocks using two advanced multivariate statistical techniques, i.e., partial least squares discriminant analysis (PLS-DA) and support vector machines (SVMs). Comparable levels of performance were achievable when using the two systems in the best signal reception conditions. Our results also suggest that SVM outperformed PLS-DA in classification performance. Then, we compared the results obtained when using pre-selected wavelength variables and broadband LIBS spectra as variable inputs. They provided approximately equivalent levels of performance. In addition, the rock slab samples were also analyzed directly after being polished. This minimized the analysis time greatly and showed improvement of classification performance compared with the pressed pellets.

  16. Cost-effective optical coherence tomography spectrometer based on a tilted fiber Bragg grating

    NASA Astrophysics Data System (ADS)

    Remund, Stefan; Bossen, Anke; Chen, Xianfeng; Wang, Ling; Adebayo, Adedotun; Zhang, Lin; Považay, Boris; Meier, Christoph

    2014-02-01

    A compact, fiber-based spectrometer for biomedical application utilizing a tilted fiber Bragg grating (TFBG) as integrated dispersive element is demonstrated. Based on a 45° UV-written PS750 TFBG a refractive spectrometer with 2.06 radiant/?m dispersion and a numerical aperture of 0.1 was set up and tested as integrated detector for an optical coherence tomography (OCT) system. Featuring a 23 mm long active region at the fiber the spectrum is projected via a cylindrical lens for vertical beam collimation and focused by an achromatic doublet onto the detector array. Covering 740 nm to 860 nm the spectrometer was optically connected to a broadband white light interferometer and a wide field scan head and electronically to an acquisition and control computer. Tomograms of ophthalmic and dermal samples obtained by the frequency domain OCT-system were obtained achieving 2.84 ?m axial and 7.6 ?m lateral resolution.

  17. Calibration of a helium-cooled infrared spatial radiometer and grating spectrometer

    NASA Technical Reports Server (NTRS)

    Jacobsen, Larry; Sargent, Steve; Wyatt, Clair L.; Steed, Allan J.

    1992-01-01

    Methods used by the Space Dynamics Laboratory of Utah State University (SDL/USU) to calibrate infrared sensors are described, using the Infrared Background Signature Survey (IBSS) spatial radiometer and grating spectrometer as examples. A calibration equation and a radiometric model are given for each sensor to describe their responsivity in terms of individual radiometric parameters. The calibration equation terms include dark offset, linearity, absolute responsivity, and measurement uncertainty, and the radiometric model domains include spatial, spectral, and temporal domains. A portable calibration facility, designed and fabricated by SDL/USU, provided collimated, extended, diffuse scatter, and Jones sources in a single cryogenic dewar. This multi-function calibrator allowed calibration personnel to complete a full calibration of the IBSS infrared radiometer and spectrometer in two 15-day periods. A calibration data system was developed to control and monitor the calibration facility, and to record and analyze sensor data.

  18. Calibration of a flat field soft x-ray grating spectrometer for laser produced plasmasa)

    NASA Astrophysics Data System (ADS)

    Park, J.; Brown, G. V.; Schneider, M. B.; Baldis, H. A.; Beiersdorfer, P.; Cone, K. V.; Kelley, R. L.; Kilbourne, C. A.; Magee, E. W.; May, M. J.; Porter, F. S.

    2010-10-01

    We have calibrated the x-ray response of a variable line spaced grating spectrometer, known as the VSG, at the Fusion and Astrophysics Data and Diagnostic Calibration Facility at the Lawrence Livermore National Laboratory (LLNL). The VSG has been developed to diagnose laser produced plasmas, such as those created at the Jupiter Laser Facility and the National Ignition Facility at LLNL and at both the Omega and Omega EP lasers at the University of Rochester's Laboratory for Laser Energetics. The bandwidth of the VSG spans the range of ˜6-60 Å. The calibration results presented here include the VSG's dispersion and quantum efficiency. The dispersion is determined by measuring the x rays emitted from the hydrogenlike and heliumlike ions of carbon, nitrogen, oxygen, neon, and aluminum. The quantum efficiency is calibrated to an accuracy of 30% or better by normalizing the x-ray intensities recorded by the VSG to those simultaneously recorded by an x-ray microcalorimeter spectrometer.

  19. Design and simulation of arrayed waveguide grating (AWG) for micro-Raman spectrometer

    NASA Astrophysics Data System (ADS)

    Cheng, Yaqin; Deng, Shengfeng; Xu, Yingchao; Lu, Miao

    2012-10-01

    Micro Raman spectrometer has broad applications for monitoring harmful chemicals in food, water and environment. Arrayed waveguide grating (AWG) is a promising device to build a dispersive micro Raman spectrometer. Comparing with the widely used demultiplexer in optical communication, AWG in spectrometer is unique due to its broad spectral range and low insert loss. In this paper, a computer algorithm routine was explored to accomplish the design of a broadband, arbitrary AWG structure. First, the focal length, length increment of adjacent waveguide and diffraction order of an AWG were figured out by a MATLAB program, the coordinates was then input into a VBScript program to generate the layout, and the layout was analyzed in OptiwaveBPM software for optical characterization. The proposed MATLAB and VBScript program was verified by the design and simulation of a 800-1000 nm range, 40 channels asymmetric AWG, a spectral resolution of 5 nm was demonstrated with insert loss of 5.03-7.16 dB. In addition, an approach to realize multimode input was introduced to reduce the optical coupling loss. Multimode light beam was firstly converted to a series of single mode beams by the methods proposed by S. G. Leon-Saval et al. in 2005. Next, these single mode beams were coupled into the input star coupler of an AWG. As a proof of this concept, a three inputs, 20 channel, 850-950 nm spectral range AWG was simulated, and merits and drawbacks of this approach were discussed.

  20. Low-energy inverse photoemission spectroscopy using a high-resolution grating spectrometer in the near ultraviolet range

    SciTech Connect

    Yoshida, Hiroyuki [Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan)] [Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan)

    2013-10-15

    An inverse photoemission spectroscopy (IPES) apparatus using a Czerny-Turner grating spectrometer is demonstrated. Previous IPES instruments based on grating spectrometers used a concave grating and operated in the vacuum ultraviolet range. The reflectance of such gratings is lower than 20% and the aberration cannot be finely corrected leading to an energy resolution of up to 0.1 eV. In the present study, employing the low energy IPES regime [H. Yoshida, Chem. Phys. Lett. 539–540, 180 (2012)], incident electrons with a kinetic energy below 5 eV are used, while photon emission in the range of between 250 and 370 nm is analyzed with a 10-cm Czerny-Turner grating spectrometer. The signal intensity is at least 30 times higher than the previous apparatus. The resolution of photon detection is set at 0.07 eV though the ultimate resolution is one order of magnitude higher. The experiment is performed both by sweeping the electron energy (isochromat mode) and by simultaneously analyzing the photon of whole wavelength range (tunable photon energy mode)

  1. Reflection Grating Array Associated with the Reflection Grating Spectrometer Developed by the Space Research Organization of the Netherlands for the X-ray Multi-Mirror Mission (XMM)

    NASA Astrophysics Data System (ADS)

    Kahn, Steven M.

    2001-04-01

    The University of California, Berkeley (UCB) served as the Principal Investigator institution for the United States participation in the development of the Reflection Grating Spectrometer (RGS) which included the design, development, fabrication, and testing of the Reflection Grating Assembly (RGA). UCB was assisted in this role by the Lawrence Livermore National Laboratory and Columbia University who provided the primary facilities, materials, services and personnel necessary to complete the development. UC Berkeley's Dr. Steven Kahn provided the technical and scientific oversight for the design. development and testing of the RGA units by monitoring the performance of the units at various stages in their development. Dr. Kahn was also the primary contact with the Space Research Organization of the Netherlands (SRON) and represented the RGA development at all SRON and European Space Agency (ESA) reviews of the RGA status. In accordance with the contract, the team designed and developed novel optical technology to meet the unique requirements of the RGS. The ESA XMM-Newton Mission carries two identical Reflection Grating Spectrometers (RGS) behind two of its three nested sets of Wolter I type mirrors. The instrument allows high-resolution measurements in the soft X-ray range (6 to 38 angstroms or 2.1 to 0.3 keV) with a maximum effective area of about 140 sq cm at 15 angstroms. Its design is optimized for the detection of the K-shell transitions of carbon, nitrogen, oxygen, neon, magnesium, and silicon. as well as the L shell transitions of iron. The RGA itself consists of two units. A structure for each unit was designed to hold up to 220 gratings. In its final configuration, one unit holds 182 gratings and the second hold 181 gratings.

  2. EGRAM- ECHELLE SPECTROGRAPH DESIGN AID

    NASA Technical Reports Server (NTRS)

    Dantzler, A. A.

    1994-01-01

    EGRAM aids in the design of spectrographic systems that utilize an echelle-first order cross disperser combination. This optical combination causes a two dimensional echellogram to fall on a detector. EGRAM describes the echellogram with enough detail to allow the user to effectively judge the feasibility of the spectrograph's design. By iteratively altering system parameters, the desired echellogram can be achieved without making a physical model. EGRAM calculates system parameters which are accurate to the first order and compare favorably to results from ray tracing techniques. The spectrographic system modelled by EGRAM consists of an entrance aperture, collimator, echelle, cross dispersion grating, focusing options, and a detector. The system is assumed to be free of aberrations and the echelle, cross disperser, and detector should be planar. The EGRAM program is menu driven and has a HELP facility. The user is prompted for information such as minimum and maximum wavelengths, slit dimensions, ruling frequencies, detector geometry, and angle of incidence. EGRAM calculates the resolving power and range of order numbers covered by the echellogram. A numerical map is also produced. This tabulates the order number, slit bandpass, and high/middle/low wavelengths. EGRAM can also compute the centroid coordinates of a specific wavelength and order (or vice versa). EGRAM is written for interactive execution and is written in Microsoft BASIC A. It has been implemented on an IBM PC series computer operating under DOS. EGRAM was developed in 1985.

  3. Calibration and in-orbit performance of the reflection grating spectrometer onboard XMM-Newton

    NASA Astrophysics Data System (ADS)

    de Vries, C. P.; den Herder, J. W.; Gabriel, C.; Gonzalez-Riestra, R.; Ibarra, A.; Kaastra, J. S.; Pollock, A. M. T.; Raassen, A. J. J.; Paerels, F. B. S.

    2015-01-01

    Context. XMM-Newton was launched on 10 December 1999 and has been operational since early 2000. One of the instruments onboard XMM-Newton is the reflection grating spectrometer (RGS). Two identical RGS instruments are available, with each RGS combining a reflection grating assembly and a camera with charge-coupled devices to record the spectra. Aims: We describe the calibration and in-orbit performance of the RGS instrument. By combining the preflight calibration with appropriate inflight calibration data including the changes in detector performance over time, we aim at profound knowledge about the accuracy in the calibration. This will be crucial for any correct scientific interpretation of spectral features for a wide variety of objects. Methods: Ground calibrations alone are not able to fully characterize the instrument. Dedicated inflight measurements and constant monitoring are essential for a full understanding of the instrument and the variations of the instrument response over time. Physical models of the instrument are tuned to agree with calibration measurements and are the basis from which the actual instrument response can be interpolated over the full parameter space. Results: Uncertainties in the instrument response have been reduced to <10% for the effective area and <6 mÅ for the wavelength scale (in the range from 8 Å to 34 Å). The remaining systematic uncertainty in the detection of weak absorption features has been estimated to be 1.5%. Conclusions: Based on a large set of inflight calibration data and comparison with other instruments onboard XMM-Newton, the calibration accuracy of the RGS instrument has been improved considerably over the preflight calibrations.

  4. Spectral resolution enhancement without increasing the number of grooves in grating-based spectrometers.

    PubMed

    Lee, Eun Seong

    2011-12-15

    A simple scheme of an optical setup to enhance the spectral resolution of diffraction gratings without increasing the number of grooves is presented. A plane-parallel mirror pair, which consists of a 100% reflectivity mirror and a 50% reflectivity mirror, is placed upon a grating. For certain values of the mirror gap and the angle between the grating and the mirrors, the effective size of the grating doubles, as does the resolution. Using a grating of 830 grooves/mm and a narrow-band diode laser that is tunable around 773 nm, we experimentally demonstrated an enhancement of the resolution by a factor of 2. PMID:22179889

  5. Design and Operation of a Frequency Doubled Nd:YAG Thomson Scattering System with Transmission Grating ICCD Spectrometer

    NASA Astrophysics Data System (ADS)

    Schoenbeck, N. L.; Dowd, A. S.; Fonck, R. J.; Schlossberg, D. J.; Winz, G. R.

    2012-10-01

    A novel Thomson scattering system has been deployed on the Pegasus Toroidal Experiment. It provides a relatively low-cost, simplified design. Scattering is achieved using a 7 ns, 2 J frequency doubled Nd:YAG laser operating at 532 nm. The laser focuses to ˜3 mm diameter within the plasma via a 7 m beam-line. The beam-line contains cameras as beam finders and remotely adjustable mirrors for shot-to-shot alignment. A custom multi-element lens collects scattered photons from 15 cm < Rmaj< 85 cm with 1.2 cm radial resolution. Eight fiber optic bundles provide 8 spatial points for sampling the laser or background light. Each set of 8 channels is measured in a single spectrometer that utilizes a high efficiency (˜80%) volume phase holographic grating and a high quantum efficiency (> 40%) image intensified CCD (ICCD) camera. Three spectrometers provide a total of 24 channels. Two interchangeable gratings exist to cover low (Te = 10--100 eV) and high (Te = 0.10--1 keV) electron temperature regimes on Pegasus. The spectrometer is optimized for ne from mid-10^18 to mid-10^19 m-3. The signal-to-noise expected is ˜0.5 of an equivalent system using Nd:YAG at 1064 nm and avalanche photodiode detectors.

  6. Phase Grating Design for a Dual-Band Snapshot Imaging Spectrometer

    Microsoft Academic Search

    James F. Scholl; Eustace L. Dereniak; Michael R. Descour; Christopher P. Tebow; Curtis E. Volin

    2003-01-01

    Infrared spectral features have proved useful in the identification of threat objects. Dual-band focal-plane arrays (FPAs) have been developed in which each pixel consists of superimposed midwave and long-wave photodetectors [Dyer and Tidrow, Conference on Infrared Detectors and Focal Plane Arrays (SPIE, Bellingham, Wash., 1999), pp. 434 -440 . Combining dual-band FPAs with imaging spectrometers capable of interband hyperspectral resolution

  7. High Resolution X-Ray Spectroscopy of zeta Puppis with the XMM-Newton Reflection Grating Spectrometer

    NASA Technical Reports Server (NTRS)

    Kahn, S. M.; Leutenegger, M. A.; Cottam, J.; Rauw, G.; Vreux, J.-M.; denBoggende, A. J. F.; Mewe, R.; Guedel, M.

    2000-01-01

    We present the first high resolution X-ray spectrum of the bright O4Ief supergiant star Puppis, obtained with the Reflection Grating Spectrometer on- board XMM-Newton. The spectrum exhibits bright emission lines of hydrogen-like and helium-like ions of nitrogen, oxygen, neon, magnesium, and silicon, as well as neon-like ions of iron. The lines are all significantly resolved, with characteristic velocity widths of order 1000 - 1500 km/ s. The nitrogen lines are especially strong, and indicate that the shocked gas in the wind is mixed with CNO-burned material, as has been previously inferred for the atmosphere of this star from ultraviolet spectra. We find that the forbidden to intercombination line ratios within the helium-like triplets are anomalously low for N VI, O VII, and Ne IX. While this is sometimes indicative of high electron density, we show that in this case, it is instead caused by the intense ultraviolet radiation field of the star. We use this interpretation to derive constraints on the location of the X-ray emitting shocks within the wind that agree remarkably well with current theoretical models for this system.

  8. Silicon immersion gratings and their spectroscopic applications

    NASA Astrophysics Data System (ADS)

    Ge, Jian; Zhao, Bo; Powell, Scott; Fletcher, Adam; Wan, Xiaoke; Chang, Liang; Jakeman, Hali; Koukis, Dimitrios; Tanner, David B.; Ebbets, Dennis; Weinberg, Jonathan; Lipscy, Sarah; Nyquist, Rich; Bally, John

    2012-09-01

    Silicon immersion gratings (SIGs) offer several advantages over the commercial echelle gratings for high resolution infrared (IR) spectroscopy: 3.4 times the gain in dispersion or ~10 times the reduction in the instrument volume, a multiplex gain for a large continuous wavelength coverage and low cost. We present results from lab characterization of a large format SIG of astronomical observation quality. This SIG, with a 54.74 degree blaze angle (R1.4), 16.1 l/mm groove density, and 50x86 mm2 grating area, was developed for high resolution IR spectroscopy (R~70,000) in the near IR (1.1-2.5 ?m). Its entrance surface was coated with a single layer of silicon nitride antireflection (AR) coating and its grating surface was coated with a thin layer of gold to increase its throughput at 1.1-2.5 ?m. The lab measurements have shown that the SIG delivered a spectral resolution of R=114,000 at 1.55 ?m with a lab testing spectrograph with a 20 mm diameter pupil. The measured peak grating efficiency is 72% at 1.55 ?m, which is consistent with the measurements in the optical wavelengths from the grating surface at the air side. This SIG is being implemented in a new generation cryogenic IR spectrograph, called the Florida IR Silicon immersion grating spectrometer (FIRST), to offer broad-band high resolution IR spectroscopy with R=72,000 at 1.4-1.8 um under a typical seeing condition in a single exposure with a 2kx2k H2RG IR array at the robotically controlled Tennessee State University 2-meter Automatic Spectroscopic Telescope (AST) at Fairborn Observatory in Arizona. FIRST is designed to provide high precision Doppler measurements (~4 m/s) for the identification and characterization of extrasolar planets, especially rocky planets in habitable zones, orbiting low mass M dwarf stars. It will also be used for other high resolution IR spectroscopic observations of such as young stars, brown dwarfs, magnetic fields, star formation and interstellar mediums. An optimally designed SIG of the similar size can be used in the Silicon Immersion Grating Spectrometer (SIGS) to fill the need for high resolution spectroscopy at mid IR to far IR (~25-300 ?m) for the NASA SOFIA airborne mission in the future.

  9. Comparison lamps automation CTIO 60 inches Echelle

    E-print Network

    Tokovinin, Andrei A.

    Comparison lamps automation CTIO 60 inches Echelle ECH60S5.1 La Serena, December 09, 2009 #12)...............................................................................12 CTIO 60 inches Echelle / Comparison lamps automation, ECH60S5.1 2 #12;Introduction The present document is just a brief summary of the work done automating the 60 inches echelle comparison lamps

  10. Spectroscopic evaluation of three different gratings used for a flat-field extreme ultraviolet spectrometer to monitor ?n =1 transitions from medium-Z impurities in 10-30Åa)

    NASA Astrophysics Data System (ADS)

    Chowdhuri, Malay Bikas; Morita, Shigeru; Goto, Motoshi; Sasai, Hiroyuki

    2008-10-01

    Spectral characteristics of varied line spacing 2400grooves/mm gratings used for a flat-field extreme ultraviolet spectrometer have been evaluated to monitor ?n =1 (n=2-3) transitions from medium-Z impurities in 10-30Å, where many spectral lines from metallic impurities closely exist. For this purpose emission spectra of the ?n =1 transitions from partially L-shell-ionized Ti and Fe have been measured in large helical device. At first, a ruled and a holographic grating were utilized for the comparative study. Both gratings suppressed higher order light effectively but spectral sensitivity was much higher for the holographic grating. The ruled grating, however, attained better spectral resolution (0.083Å at 18.97Å) in the 10-100Å range compared to that (0.130Å) of the holographic grating. After that a recently developed new holographic grating with different laminar shapes and line spacings has attempted to improve the spectral resolution. As a result, it has considerably improved the spectral resolution in the 10-30Å range, i.e., ˜0.090Å. However, it is found that the experimentally obtained spectral resolution is quit poor compared to the computationally simulated one, suggesting a technical difficulty in manufacturing exactly the varied line spacing of the holographic grating at such a short wavelength range.

  11. A narrow-band tunable diode laser system with grating feedback, and a saturated absorption spectrometer for Cs and Rb

    Microsoft Academic Search

    K. B. MacAdam; A. Steinbach; C. Wieman

    1992-01-01

    Detailed instructions for the construction and operation of a diode laser system with optical feedback are presented. This system uses feedback from a diffraction grating to provide a narrow-band continuously tuneable source of light at red or near-IR wavelengths. These instructions include machine drawings for the parts to be constructed, electronic circuit diagrams, and prices and vendors of the items

  12. Fabrication and testing of a silicon immersion grating for infrared spectroscopy

    SciTech Connect

    Kuzmenko, P.J.; Ciarlo, D.R.; Stevens, C.G.

    1994-07-25

    Recent advances in silicon micromachining techniques (e.g. anisotropic etching) allow the fabrication of very coarse infrared echelle gratings. When used in immersion mode, the dispersion is increased proportionally to the refractive index. This permits a very significant reduction in the overall size of a spectrometer while maintaining the same resolution. We have fabricated a right triangular prism (30{times}60{times}67 mm with a rectangular entrance face 30{times}38 mm) from silicon with a grating etched into the face of the hypotenuse. The grating covers an area of 32 mm by 64 mm and has a 97.5 PM periodicity with a blaze angle of 63.4{sup o}. The groove surfaces are very smooth with a roughness of a few manometers. Random defects in the silicon are the dominant source of grating scatter ({approx} 12% at 3.39 {mu}m). We measure a grating ghost intensity of 1.2%. The diffraction peak is quite narrow, slightly larger than the Airy disc diameter at F/12. However due to wavefront aberrations, perhaps 15--20% of the diffracted power is in the peak with the rest distributed in a diameter roughly five times the Airy disc.

  13. High resolution spectrometers for planetary spacecraft

    NASA Astrophysics Data System (ADS)

    Korablev, O.; Bertaux, J. L.; Vinogradov, I.; Kalinnikov, Yu.; Nevejans, D.; Neefs, E.; Le Barbu, T.; Durry, G.; Fedorova, A.; Grigoriev, A.

    Spectral measurements with high resolution give access to planetary atmospheres when observing from the Earth. Very high spectral resolution allows Doppler separation of the spectral lines in the planetary atmosphere from telluric ones, thus enabling to detect and to measure minor constituents and isotopic composition. These measurements, however, are generally full-disk averaged; also it is difficult to measure molecules abundant in the Earth's atmosphere. Therefore, spacecraft measurements at high spectral resolution are of great value in planetary missions. A review of spectrometers used in deep space missions and on the Earth orbit will be given; in particular, solar occultation high-resolution measurements will be addressed. The mass of existing state-of-the-art instruments (several tens to hundreds of kilograms) prevents them from being sent toward other planets. Even in the remote sensing of the Earth the tendencies are that compact and lightweight instrumentation has more chances to be flown. A new concept of a high-resolution near-IR spectrometer consisting of an echelle grating combined with an acousto-optic tunable filter (AOTF) for separation of diffraction orders, is developed for space-borne studies of planetary atmospheres. An AOTF spectrometer with lower resolution (no echelle grating, ? v/?? s? 1200, mass 800 g) has been qualified and is now operational on the Mars Express orbiter. New compact design within the mass budget of 3-5 kg allows to reach the resolving power ? v/?? s of 20000-30000. A spectrometer, based on this principle, SOIR (Solar Occultation InfraRed) is being built for Venus Express (2005) ESA mission to study atmospheric structure and composition above clouds. The concept and the potential of such instrument for the studies of Mars and the Earth atmospheres, in particular, measurements of isotopes of water in the atmosphere, either in solar occultation profiling, or (on the Earth) observing solar glint for integral quantities of the components. Small size of hardware makes the instrument ideal for micro-satellites, which are now agile enough to provide necessary pointing for solar occultation or glint observations.

  14. Electrically-programmable diffraction grating

    DOEpatents

    Ricco, A.J.; Butler, M.A.; Sinclair, M.B.; Senturia, S.D.

    1998-05-26

    An electrically-programmable diffraction grating is disclosed. The programmable grating includes a substrate having a plurality of electrodes formed thereon and a moveable grating element above each of the electrodes. The grating elements are electrostatically programmable to form a diffraction grating for diffracting an incident beam of light as it is reflected from the upper surfaces of the grating elements. The programmable diffraction grating, formed by a micromachining process, has applications for optical information processing (e.g. optical correlators and computers), for multiplexing and demultiplexing a plurality of light beams of different wavelengths (e.g. for optical fiber communications), and for forming spectrometers (e.g. correlation and scanning spectrometers). 14 figs.

  15. Adaptive optics high-resolution IR spectroscopy with silicon grisms and immersion gratings

    NASA Astrophysics Data System (ADS)

    Ge, Jian; McDavitt, Daniel L.; Chakraborty, Abhijit; Bernecker, John L.; Miller, Shane

    2003-02-01

    The breakthrough of silicon immersion grating technology at Penn State has the ability to revolutionize high-resolution infrared spectroscopy when it is coupled with adaptive optics at large ground-based telescopes. Fabrication of high quality silicon grism and immersion gratings up to 2 inches in dimension, less than 1% integrated scattered light, and diffraction-limited performance becomes a routine process thanks to newly developed techniques. Silicon immersion gratings with etched dimensions of ~ 4 inches are being developed at Penn State. These immersion gratings will be able to provide a diffraction-limited spectral resolution of R = 300,000 at 2.2 micron, or 130,000 at 4.6 micron. Prototype silicon grisms have been successfully used in initial scientific observations at the Lick 3m telescope with adaptive optics. Complete K band spectra of a total of 6 T Tauri and Ae/Be stars and their close companions at a spectral resolution of R ~ 3000 were obtained. This resolving power was achieved by using a silicon echelle grism with a 5 mm pupil diameter in an IR camera. These results represent the first scientific observations conducted by the high-resolution silicon grisms, and demonstrate the extremely high dispersing power of silicon-based gratings. New discoveries from this high spatial and spectral resolution IR spectroscopy will be reported. The future of silicon-based grating applications in ground-based AO IR instruments is promising. Silicon immersion gratings will make very high-resolution spectroscopy (R > 100,000) feasible with compact instruments for implementation on large telescopes. Silicon grisms will offer an efficient way to implement low-cost medium to high resolution IR spectroscopy (R ~ 1000-50000) through the conversion of existing cameras into spectrometers by locating a grism in the instrument's pupil location.

  16. Development of silicon grisms and immersion gratings for high-resolution infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Ge, Jian; McDavitt, Daniel L.; Bernecker, John L.; Miller, Shane; Ciarlo, Dino R.; Kuzmenko, Paul J.

    2002-01-01

    We report new results on silicon grism and immersion grating development using photolithography and anisotropic chemical etching techniques, which include process recipe finding, prototype grism fabrication, lab performance evaluation and initial scientific observations. The very high refractive index of silicon (n=3.4) enables much higher dispersion power for silicon-based gratings than conventional gratings, e.g. a silicon immersion grating can offer a factor of 3.4 times the dispersion of a conventional immersion grating. Good transmission in the infrared (IR) allows silicon-based gratings to operate in the broad IR wavelength regions (~1- 10 micrometers and far-IR), which make them attractive for both ground and space-based spectroscopic observations. Coarser gratings can be fabricated with these new techniques rather than conventional techniques, allowing observations at very high dispersion orders for larger simultaneous wavelength coverage. We have found new etching techniques for fabricating high quality silicon grisms with low wavefront distortion, low scattered light and high efficiency. Particularly, a new etching process using tetramethyl ammonium hydroxide (TMAH) is significantly simplifying the fabrication process on large, thick silicon substrates, while providing comparable grating quality to our traditional potassium hydroxide (KOH) process. This technique is being used for fabricating inch size silicon grisms for several IR instruments and is planned to be used for fabricating ~ 4 inch size silicon immersion gratings later. We have obtained complete K band spectra of a total of 6 T Tauri and Ae/Be stars and their close companions at a spectral resolution of R ~ 5000 using a silicon echelle grism with a 5 mm pupil diameter at the Lick 3m telescope. These results represent the first scientific observations conducted by the high-resolution silicon grisms, and demonstrate the extremely high dispersing power of silicon- based gratings. The future of silicon-based grating applications in ground and space-based IR instruments is promising. Silicon immersion gratings will make very high-resolution spectroscopy (R>100,000) feasible with compact instruments for implementation on large telescopes. Silicon grisms will offer an efficient way to implement low-cost medium to high resolution IR spectroscopy (R~ 1000-50000) through the conversion of existing cameras into spectrometers by locating a grism in the instrument's pupil location.

  17. Temps-Frquence et Temps-Echelle

    E-print Network

    Rioul, Olivier

    Analyse Temps-Fréquence et Temps-Echelle O. Rioul Fréquence Résolution temps-fréquence Pourquoi l'analyse temps-fréquence ? T.F. Court Terme Ondelettes Transformations bilinéaires Boîtes à outils Bibliographie Analyse Temps-Fréquence et Temps-Echelle Olivier Rioul Dept. COMELEC GET/ENST olivier.rioul@enst.fr perso

  18. DYNAMICS OF X-RAY-EMITTING EJECTA IN THE OXYGEN-RICH SUPERNOVA REMNANT PUPPIS A REVEALED BY THE XMM-NEWTON REFLECTION GRATING SPECTROMETER

    SciTech Connect

    Katsuda, Satoru; Tamagawa, Toru [RIKEN - Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Ohira, Yutaka [Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1 Fuchinobe Sagamihara 252-5258 (Japan); Mori, Koji [Department of Applied Physics, Faculty of Engineering, University of Miyazaki, 1-1 Gakuen Kibana-dai Nishi, Miyazaki 889-2192 (Japan); Tsunemi, Hiroshi; Koyama, Katsuji [Department of Earth and Space Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 60-0043 (Japan); Uchida, Hiroyuki [Department of Physics, Kyoto University, Kitashirakawa-oiwake-cho, Sakyo, Kyoto 606-8502 (Japan)

    2013-05-10

    Using the unprecedented spectral resolution of the reflection grating spectrometer (RGS) on board XMM-Newton, we reveal dynamics of X-ray-emitting ejecta in the oxygen-rich supernova remnant Puppis A. The RGS spectrum shows prominent K-shell lines, including O VII He{alpha} forbidden and resonance, O VIII Ly{alpha}, O VIII Ly{beta}, and Ne IX He{alpha} resonance, from an ejecta knot positionally coincident with an optical oxygen-rich filament (the so-called {Omega} filament) in the northeast of the remnant. We find that the line centroids are blueshifted by 1480 {+-} 140 {+-} 60 km s{sup -1} (the first and second term errors are measurement and calibration uncertainties, respectively), which is fully consistent with that of the optical {Omega} filament. Line broadening at 654 eV (corresponding to O VIII Ly{alpha}) is obtained to be {sigma} {approx}< 0.9 eV, indicating an oxygen temperature of {approx}< 30 keV. Analysis of XMM-Newton MOS spectra shows an electron temperature of {approx}0.8 keV and an ionization timescale of {approx}2 Multiplication-Sign 10{sup 10} cm{sup -3} s. We show that the oxygen and electron temperatures as well as the ionization timescale can be reconciled if the ejecta knot was heated by a collisionless shock whose velocity is {approx}600-1200 km s{sup -1} and was subsequently equilibrated due to Coulomb interactions. The RGS spectrum also shows relatively weak K-shell lines of another ejecta feature located near the northeastern edge of the remnant, from which we measure redward Doppler velocities of 650 {+-} 70 {+-} 60 km s{sup -1}.

  19. IR spectrometers for Venus and Mars measurements

    NASA Astrophysics Data System (ADS)

    Drummond, Rachel; Neefs, Eddy; Vandaele, Ann C.

    2012-07-01

    The SOIR spectrometer [1] is an infra-red spectrometer that has performed over 500 solar occultation measurements of the Venus atmosphere, profiling major and minor constituents and studying aerosol absorption, temperature and pressure effects. NOMAD is a 3-channel spectrometer for Mars occultation, limb and nadir measurements. 2 channels are infra-red, the other UV-visible. We will present the technology that enables SOIR and NOMAD to get to parts per billion mixing ratio sensitivities for trace atmospheric components and highlight the improvements made to the SOIR design to enable nadir viewing with NOMAD. Key components include the Acousto-Optical Tunable Filter with radio frequency driver that allows these spectrometers to select the wavelength domain under observation with no need for mechanical moving parts. It also allows background measurements because it is opaque when no RF is applied. The grating with 4 grooves/mm is a very hard to manufacture optical component, and suppliers were very difficult to find. The detector-cooler combination (working at 90K) is from Sofradir/Ricor and the model on board Venus Express is still working after 6 years in space (more on/off cycles that ON hour lifetime problem). The detector MCT mix is slightly altered for nadir observation, in order to reduce thermal background noise and the nadir channel spectrometer is cooled down to 173K by a large V-groove radiator. All the optical components have been enlarged to maximise signal throughput and the slit (that determines spatial and spectral resolution) has also been increased. The spacecraft attitude control system switches from yaw steering for nadir to inertial pointing for solar occultations. 1. Nevejans, D., E. Neefs, E. Van Ransbeeck, S. Berkenbosch, R. Clairquin, L. De Vos, W. Moelans, S. Glorieux, A. Baeke, O. Korablev, I. Vinogradov, Y. Kalinnikov, B. Bach, J.P. Dubois, and E. Villard, Compact high-resolution space-borne echelle grating spectrometer with AOTF based on order sorting for the infrared domain from 2.2 to 4.3 micrometer. Applied Optics, 45(21), 5191-5206 (2006)

  20. The FIRE infrared spectrometer at Magellan: construction and commissioning

    E-print Network

    Simcoe, Robert A.

    We describe the construction and commissioning of FIRE, a new 0.8-2.5?m echelle spectrometer for the Magellan/ Baade 6.5 meter telescope. FIRE delivers continuous spectra over its full bandpass with nominal spectral ...

  1. The Spectrometer

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    2012-01-01

    In the fall of 1999 I was shown an Ocean Optics spectrometer-in-the-computer at St. Patricks College at Maynooth, Ireland, and thought that I had seen heaven. Of course, it could not resolve the sodium D-lines (I had done that many years before with a homemade wire diffraction grating), and I began to realize that inside was some familiar old…

  2. Warm infrared echelle spectrograph (WINERED): testing of optical components and performance evaluation of the optical system

    NASA Astrophysics Data System (ADS)

    Yasui, Chikako; Kondo, Sohei; Ikeda, Yuji; Minami, Atsushi; Motohara, Kentaro; Kobayashi, Naoto

    2008-07-01

    We are developing a new NIR high-resolution (Rmax = 100, 000) and high-sensitive spectrograph WINERED, specifically customized for short NIR bands at 0.9-1.35 ?m. WINERED employs the following novel approaches in the optical system: portable design with a ZnSe immersion grating and warm optics without any cold stops. These concepts result in several essential advantages: easy to build, align, and maintain; these result in a short development time and low cost. WINERED is also equipped with a "normal echelle mode", which can cover the entire wavelength range simultaneously with R = 30, 000. In this poster paper, we will present the results of the detailed testing of optical components and the laboratory first light for the normal echelle mode. See Poster paper 7018-183 by Ikeda et al. in another session for the status of the development of the ZnSe immersion grating for R = 100, 000. We plan to complete the normal mode first by the end of 2008 and will install the immersion grating in 2010.

  3. IUE Echelle Investigations of V471 Tauri

    NASA Astrophysics Data System (ADS)

    Sion, Edward M.

    We propose a comprehensive IUE echelle investigation of the Hyades, eclipsing-spectroscopic, pre-cataclysmic binary V471 Tauri utilizing SWP and LWP echelle images taken at selected phases around the orbit and velocitycompensated for the orbited motion. The scientific objectives of our proposed program are: (1) to search for the spectral signature of mass loss from the chromospherically very active, rapidly rotating K2 dwarf and resolve the nature of velocity-shifted narrow absorption features observed at coincident velocity, blueward and redward of both the h and k emission cores of MgII; (2) to model for the first time the chromospheric structure of the K2 dwarf using irradition by the white dwarf as a "probe" (3) to confirm the presence of expanding, high velocity, circumbinary gas in the line of sight to V471 Tauri and search for other circumbinary absorption with a full IUE SWP echelle exposure; (4) to search for further evidence of accretion flow and intrasystem gas, strongly implied by EXOSAT soft x-ray oscillation and x-ray dips as well as to confirm and interpret the origin and nature of detected hot gas, co-moving with the white dwarf; (5) to search for the weak absorption signature of accreted metals and/or helium in the Einstein-redshifted rest frame by co-adding two orbital motioncompensated SWP centered at phase 0.25 and 0.75. Our proposed echelle investigations will result in a greater understanding of mass loss from cool dwarfs, the chromospheric structure of cool dwarfs including the effect of rapid rotation and external irradiation, mass and angular momentum loss in a pre-cataclysmic binary, the physics of wind/flare accretion (and diffusion) onto a hot white dwarf, the production mechanism of soft x-ray pulsations associated with the white dwarf and the nature of expanding high velocity gas around the system.

  4. Scattered light in the STIS echelle modes

    NASA Technical Reports Server (NTRS)

    Landsman, W.; Bowers, C.

    1997-01-01

    The Space Telescope Imaging Spectrograph (STIS) echelle spectra obtained during the Early Release Observations have non-zero residuals in the cores of saturated interstellar lines, indicating the need for a scattered light correction. A rough measure of the magnitude of the needed correction shows the ratio of the interorder to the in-order flux in different echelle modes in both pre-launch calibration images of a continuum lamp source and in post-launch images of stellar continuum sources. The interorder and in-order fluxes are computed by averaging the central 200 pixels in the dispersion direction. The amount of scattered light in the interorder region rises toward shorter wavelengths for two reasons: (1) the order separation decreases toward shorter wavelengths; and (2) the amount of echelle scattering is expected to have an inverse dependence on wavelength. At the shortest wavelengths the fraction of light scattered into the interorder region can be 10% for the Near-ultraviolet-Multi-Anode Microchannel Array (NUV-MAMA) and 15% for the Far-ultraviolet-Multi-Anode Microchannel Array (FUV-MAMA).

  5. Grating imaging scanning lithography for fabrication of large sized grating

    NASA Astrophysics Data System (ADS)

    Yu, Bin; Jia, Wei; Zhou, Changhe

    2012-11-01

    Diffraction grating is a high-resolution dispersion optical element. It has been widely used as the key component in optical spectroscopy, telecommunication multiplexing and laser systems, etc. Recently there is a growing demand for large-sized diffraction gratings in spectrometers industry, laser fusion facility, and its fabrication method is also a hot topic now. To fabricate large sized gratings, we have developed a grating imaging scanning lithography system. In this technology, the phase grating with jagged edge is used to generate diffractive beams and the spatial filter is used to select +/-1 order diffractive beams. Then two-beam interference on the substrate forms the grating fringes. At the same time, a 4f-system is used to form an identical image with clear boundary in the interference area. A high precision twodimensional mobile station, which enables the accurate positioning and move of the substrate, is utilized for complementary cyclical scanning, thus the image stitching errors are effectively eliminated. With this technology, we have fabricated a grating with period of 20?m and size of 100mm×100mm. In this paper the grating imaging scanning lithography procedure is described step by step. The principles and the experimental results are also explained in detail. With the characteristics of a simple structure, high energy utilization and stability, this new lithography technology should be an efficient way to fabricate large sized grating in the future.

  6. Electromagnetic diffraction efficiencies for plane reflection diffraction gratings

    NASA Technical Reports Server (NTRS)

    Marathay, A. S.; Shrode, T. E.

    1973-01-01

    Results are presented of research activities on holographic grating research. A large portion of this work was performed using rigorous vector diffraction theory, therefore, the necessary theory has been included in this report. The diffraction efficiency studies were continued using programs based on a rigorous theory. The simultaneous occurrence of high diffraction efficiencies and the phenomenon of double Wood's anomalies is demonstrated along with a graphic method for determining the necessary grating parameters. Also, an analytical solution for a grating profile that is perfectly blazed is obtained. The performance of the perfectly blazed grating profile is shown to be significantly better than grating profiles previously studied. Finally, a proposed method is described for the analysis of coarse echelle gratings using rigorous vector diffraction that is currently being developed.

  7. Electromagnetic diffraction efficiencies for plane reflection diffraction gratings

    NASA Technical Reports Server (NTRS)

    Marathay, A. S.; Shrode, T. E.

    1974-01-01

    The theory and computer programs, based on electromagnetic theory, for the analysis and design of echelle gratings were developed. The gratings are designed for instruments that operate in the ultraviolet portion of the spectrum. The theory was developed so that the resulting computer programs will be able to analyze deep (up to 30 wavelengths) gratings by including as many as 100 real or homogeneous diffraction orders. The program calculates the complex amplitude coefficient for each of the diffracted orders. A check on the numerical method used to solve the integral equations is provided by a conservation of energy calculation.

  8. The GMT-CFA-CARNEGIE-CATOLICA LARGE EARTH FINDER (G-CLEF): A Fiber-fed, Optical Echelle Spectrograph For The Giant Magellan Telescope

    NASA Astrophysics Data System (ADS)

    Szentgyorgyi, Andrew; Furesz, G.; Frebel, A.; Geary, J.; Evans, I.; Norton, T.; Hertz, E.; DePonte Evans, J.; Jordan, A.; Guzman, D.; Epps, H.; Barnes, S.; Crane, J.

    2011-01-01

    The GMT-CfA-Carnegie-Catolica Large Earth Finder (G-CLEF) is a fiber-fed optical echelle spectrograph in concept design study phase for first light at the Giant Magellan Telescope. G-CLEF is designed to be a multipurpose echelle spectrograph that operates in a number of modes so as to enable precision radial velocity (RV) measurements, detailed abundance studies, isotopic abundance measurements and probe the IGM and ISM at high Z. Four resolution modes are implemented with image and pupil slicing. Extremely precise RV will be achieved by vacuum enclosing the spectrograph, with advanced fiber scrambling and state-of-the-art calibrators, especially ultra stabilized etalons and possibly laser frequency combs. The optical design is a asymmetric white pupil design with two camera arms splitting the 350 nm - 950 nm passband into red and blue channels. G-CLEF will have an extremely large, mosaiced echelle grating and volume phase holograph cross dispersers.

  9. Planar double-grating microspectrometer

    Microsoft Academic Search

    Semen Grabarnik; Reinoud Wolffenbuttel; Arwin Emadi; Mikhail Loktev; Elena Sokolova; Gleb Vdovin

    2007-01-01

    We report on a miniature spectrometer with a volume of 0.135 cm3 and dimensions of 3x3x11 mm, mounted directly on the surface of a CCD sensor. The spectrometer is formed by two flat diffraction gratings that are designed to perform both the dispersion and imaging functions, eliminating the need for any spherical optics. Two separate parts of the device were

  10. Performance of a laser frequency comb calibration system with a high-resolution solar echelle spectrograph

    NASA Astrophysics Data System (ADS)

    Doerr, H.-P.; Kentischer, T. J.; Steinmetz, T.; Probst, R. A.; Franz, M.; Holzwarth, R.; Udem, Th.; Hänsch, T. W.; Schmidt, W.

    2012-09-01

    Laser frequency combs (LFC) provide a direct link between the radio frequency (RF) and the optical frequency regime. The comb-like spectrum of an LFC is formed by exact equidistant laser modes, whose absolute optical frequencies are controlled by RF-references such as atomic clocks or GPS receivers. While nowadays LFCs are routinely used in metrological and spectroscopic fields, their application in astronomy was delayed until recently when systems became available with a mode spacing and wavelength coverage suitable for calibration of astronomical spectrographs. We developed a LFC based calibration system for the high-resolution echelle spectrograph at the German Vacuum Tower Telescope (VTT), located at the Teide observatory, Tenerife, Canary Islands. To characterize the calibration performance of the instrument, we use an all-fiber setup where sunlight and calibration light are fed to the spectrograph by the same single-mode fiber, eliminating systematic effects related to variable grating illumination.

  11. Nanostructure Diffraction Gratings for Integrated Spectroscopy and Sensing

    NASA Technical Reports Server (NTRS)

    Guo, Junpeng (Inventor)

    2015-01-01

    The present disclosure pertains to metal or dielectric nanostructures of the subwavelength scale within the grating lines of optical diffraction gratings. The nanostructures have surface plasmon resonances or non-plasmon optical resonances. A linear photodetector array is used to capture the resonance spectra from one of the diffraction orders. The combined nanostructure super-grating and photodetector array eliminates the use of external optical spectrometers for measuring surface plasmon or optical resonance frequency shift caused by the presence of chemical and biological agents. The nanostructure super-gratings can be used for building integrated surface enhanced Raman scattering (SERS) spectrometers. The nanostructures within the diffraction grating lines enhance Raman scattering signal light while the diffraction grating pattern of the nanostructures diffracts Raman scattering light to different directions of propagation according to their wavelengths. Therefore, the nanostructure super-gratings allows for the use of a photodetector array to capture the surface enhanced Raman scattering spectra.

  12. Modelling high resolution Echelle spectrographs for calibrations: Hanle Echelle spectrograph, a case study

    NASA Astrophysics Data System (ADS)

    Chanumolu, Anantha; Jones, Damien; Thirupathi, Sivarani

    2015-06-01

    We present a modelling scheme that predicts the centroids of spectral line features for a high resolution Echelle spectrograph to a high accuracy. Towards this, a computing scheme is used, whereby any astronomical spectrograph can be modelled and controlled without recourse to a ray tracing program. The computations are based on paraxial ray trace and exact corrections added for certain surface types and Buchdahl aberration coefficients for complex modules. The resultant chain of paraxial ray traces and corrections for all relevant components is used to calculate the location of any spectral line on the detector under all normal operating conditions with a high degree of certainty. This will allow a semi-autonomous control using simple in-house, programming modules. The scheme is simple enough to be implemented even in a spreadsheet or in any scripting language. Such a model along with an optimization routine can represent the real time behaviour of the instrument. We present here a case study for Hanle Echelle Spectrograph. We show that our results match well with a popular commercial ray tracing software. The model is further optimized using Thorium Argon calibration lamp exposures taken during the preliminary alignment of the instrument. The model predictions matched the calibration frames at a level of 0.08 pixel. Monte Carlo simulations were performed to show the photon noise effect on the model predictions.

  13. Grating shearography

    NASA Astrophysics Data System (ADS)

    Bulhak, Jacek; Surrel, Yves

    1999-08-01

    This paper describes grating shearography as a technique for direct measurement of in-plane strains and out-of-plane slopes. This technique has many interesting features for mechanical engineering: strains are measured without numerical differentiation, so a good spatial resolution can be obtained; it is also fairly insensitive to vibrations; full in-plane and out-of-plane information can be gathered simultaneously; finally, it is easy to switch from grating shearography to grating interferometry, in order to have also the displacement field. We present the theoretical basis of the method and the preliminary measurements on a graphite/epoxy composite sample under Iosipescu shear testing. Results are compared with FEM simulation.

  14. Multiple order common path spectrometer

    NASA Technical Reports Server (NTRS)

    Newbury, Amy B. (Inventor)

    2010-01-01

    The present invention relates to a dispersive spectrometer. The spectrometer allows detection of multiple orders of light on a single focal plane array by splitting the orders spatially using a dichroic assembly. A conventional dispersion mechanism such as a defraction grating disperses the light spectrally. As a result, multiple wavelength orders can be imaged on a single focal plane array of limited spectral extent, doubling (or more) the number of spectral channels as compared to a conventional spectrometer. In addition, this is achieved in a common path device.

  15. Development of the Colorado High-resolution Echelle Stellar Spectrograph (CHESS)

    NASA Astrophysics Data System (ADS)

    France, Kevin; Beasley, Matthew; Kane, Robert; Nell, Nicholas; Burgh, Eric B.; Green, James C.

    2012-09-01

    A key astrophysical theme that will drive future UV/optical space missions is the life cycle of cosmic matter, from the flow of intergalactic gas into galaxies to the formation and evolution of exoplanetary systems. Spectroscopic systems capable of delivering high resolution with low backgrounds will be essential to addressing these topics. Towards this end, we are developing a rocket-borne instrument that will serve as a pathfinder for future high-sensitivity, highresolution UV spectrographs. The Colorado High-resolution Echelle Stellar Spectrograph (CHESS) will provide 2 km s-1 velocity resolution (R = 150,000) over the 100 - 160 nm bandpass that includes key atomic and molecular spectral diagnostics for the intergalactic medium (H I Lyman-series, O VI, N V, and C IV), exoplanetary atmospheres (H I Lyman-alpha, O I, and C II), and protoplanetary disks (H2 and CO electronic band systems). CHESS uses a novel mechanical collimator comprised of an array of 10 mm x 10 mm stainless steel tubes to feed a low-scatter, 69 grooves mm-1 echelle grating. The cross-disperser is a holographically ruled toroid, with 351 grooves mm-1. The spectral orders can be recorded with either a 40 mm cross-strip microchannel plate detector or a 3.5k x 3.5k ?-doped CCD. The microchannel plate will deliver 30 ?m spatial resolution and employs new 64 amp/axis electronics to accommodate high count rate observations of local OB stars. CHESS is scheduled to be launched aboard a NASA Terrier/Black Brant IX sounding rocket from White Sands Missile Range in the summer of 2013.

  16. Mathematical Simulation for Integrated Linear Fresnel Spectrometer Chip

    NASA Technical Reports Server (NTRS)

    Park, Yeonjoon; Yoon, Hargoon; Lee, Uhn; King, Glen C.; Choi, Sang H.

    2012-01-01

    A miniaturized solid-state optical spectrometer chip was designed with a linear gradient-gap Fresnel grating which was mounted perpendicularly to a sensor array surface and simulated for its performance and functionality. Unlike common spectrometers which are based on Fraunhoffer diffraction with a regular periodic line grating, the new linear gradient grating Fresnel spectrometer chip can be miniaturized to a much smaller form-factor into the Fresnel regime exceeding the limit of conventional spectrometers. This mathematical calculation shows that building a tiny motionless multi-pixel microspectrometer chip which is smaller than 1 cubic millimter of optical path volume is possible. The new Fresnel spectrometer chip is proportional to the energy scale (hc/lambda), while the conventional spectrometers are proportional to the wavelength scale (lambda). We report the theoretical optical working principle and new data collection algorithm of the new Fresnel spectrometer to build a compact integrated optical chip.

  17. The Ultraviolet Coronagraph Spectrometer for the solar and heliospheric observatory

    Microsoft Academic Search

    J. L. Kohl; R. Esser; L. D. Gardner; S. Habbal; P. S. Daigneau; E. F. Dennis; G. U. Nystrom; A. Panasyuk; J. C. Raymond; P. L. Smith; L. Strachan; A. A. Ballegooijen; G. Noci; S. Fineschi; M. Romoli; A. Ciaravella; A. Modigliani; M. C. E. Huber; E. Antonucci; C. Benna; S. Giordano; G. Tondello; P. Nicolosi; G. Naletto; C. Pernechele; D. Spadaro; G. Poletto; S. Livi; O. Lühe; J. Geiss; J. G. Timothy; G. Gloeckler; A. Allegra; G. Basile; R. Brusa; B. Wood; O. H. W. Siegmund; W. Fowler; R. Fisher; M. Jhabvala

    1995-01-01

    The SOHO Ultraviolet Coronagraph Spectrometer (UVCS\\/SOHO) is composed of three reflecting telescopes with external and internal occultation and a spectrometer assembly consisting of two toric grating spectrometers and a visible light polarimeter. The purpose of the UVCS instrument is to provide a body of data that can be used to address a broad range of scientific questions regarding the nature

  18. Grating shearography

    Microsoft Academic Search

    Jacek Bulhak; Yves Surrel

    1999-01-01

    This paper describes grating shearography as a technique for direct measurement of in-plane strains and out-of-plane slopes. This technique has many interesting features for mechanical engineering: strains are measured without numerical differentiation, so a good spatial resolution can be obtained; it is also fairly insensitive to vibrations; full in-plane and out-of-plane information can be gathered simultaneously; finally, it is easy

  19. Monolithic spectrometer

    DOEpatents

    Rajic, Slobodan (Knoxville, TN); Egert, Charles M. (Oak Ridge, TN); Kahl, William K. (Knoxville, TN); Snyder, Jr., William B. (Knoxville, TN); Evans, III, Boyd M. (Oak Ridge, TN); Marlar, Troy A. (Knoxville, TN); Cunningham, Joseph P. (Oak Ridge, TN)

    1998-01-01

    A monolithic spectrometer is disclosed for use in spectroscopy. The spectrometer is a single body of translucent material with positioned surfaces for the transmission, reflection and spectral analysis of light rays.

  20. Fiber grating spectra

    Microsoft Academic Search

    T. Erdogan

    1997-01-01

    In this paper, we describe the spectral characteristics that can be achieved in fiber reflection (Bragg) and transmission gratings. Both principles for understanding and tools for designing fiber gratings are emphasized. Examples are given to illustrate the wide variety of optical properties that are possible in fiber gratings. The types of gratings considered include uniform, apodized, chirped, discrete phase-shifted, and

  1. On-chip random spectrometer

    NASA Astrophysics Data System (ADS)

    Redding, B.; Liew, S. F.; Sarma, R.; Cao, H.

    2014-05-01

    Spectrometers are widely used tools in chemical and biological sensing, material analysis, and light source characterization. The development of a high-resolution on-chip spectrometer could enable compact, low-cost spectroscopy for portable sensing as well as increasing lab-on-a-chip functionality. However, the spectral resolution of traditional grating-based spectrometers scales with the optical pathlength, which translates to the linear dimension or footprint of the system, which is limited on-chip. In this work, we utilize multiple scattering in a random photonic structure fabricated on a silicon chip to fold the optical path, making the effective pathlength much longer than the linear dimension of the system and enabling high spectral resolution with a small footprint. Of course, the random spectrometer also requires a different operating paradigm, since different wavelengths are not spatially separated by the random structure, as they would be by a grating. Instead, light transmitted through the random structure produces a wavelengthdependent speckle pattern which can be used as a fingerprint to identify the input spectra after calibration. In practice, these wavelength-dependent speckle patterns are experimentally measured and stored in a transmission matrix, which describes the spectral-to-spatial mapping of the spectrometer. After calibrating the transmission matrix, an arbitrary input spectrum can be reconstructed from its speckle pattern. We achieved sub-nm resolution with 25 nm bandwidth at a wavelength of 1500 nm using a scattering medium with largest dimension of merely 50 ?m.

  2. Development of Multiple-Element Flame Emission Spectrometer Using CCD Detection

    ERIC Educational Resources Information Center

    Seney, Caryn S.; Sinclair, Karen V.; Bright, Robin M.; Momoh, Paul O.; Bozeman, Amelia D.

    2005-01-01

    The full wavelength coverage of charge coupled device (CCD) detector when coupled with an echelle spectrography, the system allows for simultaneously multiple element spectroscopy to be performed. The multiple-element flame spectrometer was built and characterized through the analysis of environmentally significant elements such as Ca, K, Na, Cu,…

  3. Field calibration of a broadband compact thermal infrared spectrometer for earth science

    Microsoft Academic Search

    William R. Johnson; Simon J. Hook; Pantazis Mouroulis; Daniel W. Wilson; Sarath D. Gunapala; Cory J. Hill; V. Realmuto; J. M. Mumolo; B. T. Eng

    2010-01-01

    We present field results showing excellent performance for a compact earth observing thermal infrared (EOTIR) hyperspectral grating spectrometer using a combination of a Quantum Well Infrared Photodetector (QWIP) and grating based Dyson spectrometer. The Dyson design allows for a very compact and optically fast system (F\\/1.6). Cooling requirements are minimized due to the single monolithic prism-like grating design. The configuration

  4. Multilayer coated gratings for phase-contrast computed tomography (CT)

    NASA Astrophysics Data System (ADS)

    Marton, Zsolt; Bhandari, Harish B.; Wen, Harold H.; Nagarkar, Vivek V.

    2014-03-01

    By using the principle of grating interferometry, X-ray phase contrast imaging can now be performed with incoherent radiation from standard X-ray tube. This approach is in stark contrast with imaging methods using coherent synchrotron X-ray sources or micro-focus sources to improve contrast. The gratings interferometer imaging technique is capable of measuring the phase shift of hard X-rays travelling through a sample, which greatly enhances the contrast of low absorbing specimen compared to conventional amplitude contrast images. The key components in this approach are the gratings which consists of alternating layers of high and low Z (atomic number) materials fabricated with high aspect ratios. Here we report on a novel method of fabricating the grating structures using the technique of electron-beam (ebeam) thin film deposition. Alternating layers of silicon (Z=14) and tungsten (Z=74) were deposited, each measuring 100 nm each, on a specially designed echelle substrate, which resulted in an aspect ratio of ~100:1. Fabrication parameters related to the thin film deposition such as geometry, directionality, film adhesion, stress and the resulting scanning electron micrographs will be discussed in detail. Using e-beam method large-area gratings with precise multilayer coating thicknesses can be fabricated economically circumventing the expensive lithography steps.

  5. Multilayer diffraction grating

    DOEpatents

    Barbee, Jr., Troy W. (Palo Alto, CA)

    1990-01-01

    This invention is for a reflection diffraction grating that functions at X-ray to VUV wavelengths and at normal angles of incidence. The novel grating is comprised of a laminar grating of period D with flat-topped grating bars. A multiplicity of layered synthetic microstructures, of period d and comprised of alternating flat layers of two different materials, are disposed on the tops of the grating bars of the laminar grating. In another embodiment of the grating, a second multiplicity of layered synthetic microstructures are also disposed on the flat faces, of the base of the grating, between the bars. D is in the approximate range from 3,000 to 50,000 Angstroms, but d is in the approximate range from 10 to 400 Angstroms. The laminar grating and the layered microstructures cooperatively interact to provide many novel and beneficial instrumentational advantages.

  6. Full image spectral analysis of elemental emissions from an echelle spectrograph

    SciTech Connect

    Spencer, W.A.

    2000-01-27

    A new algorithm compares the background corrected echelle emission image obtained from reference standards to images of unknowns for quantitative elemental analyses. Wavelength was not used in the calculations but instead pixel position and intensity. The data reduction solution was unique to the particular detector/spectrometer. The approach was found useful for several types of images including ICP, DCP and glow discharge images. The analysis scheme required that the emission pattern of standards and background be held in memory. A dual weighting scheme was used that decreased the importance of pixels in high background areas and enhanced the importance of signals from pixels where the standards had emissions. Threshold values were used to limit the calculations to signals in the linear range of the electronics. Logarithmic weighting, (by taking the square root), was found to work well for weighting pixels from the standards. This assured that minor emissions had some influence on the data fit. In the program the best-fit scalar was determined using simple iterative guess, change and test approaches. The test looked for the minimum least square residual value in the areas of the flagged pixels.

  7. Research directed toward improved echelles for the ultraviolet

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Research was undertaken to demonstrate that improved efficiencies for low frequency gratings are obtainable with the careful application of present technology. The motivation for the study was the desire to be assured that the grating-efficiency design goals for potential Space Telescope spectrographs can be achieved. The work was organized to compare gratings made with changes in the three specific parameters: the ruling tool profile, the coating material, and the lubricants used during the ruling process. A series of coatings and test gratings were fabricated and were examined for surface smoothness with a Nomarski Differential Interference Microscope and an electron microscope. Photomicrographs were obtained to show the difference in smoothness of the various coatings and rulings. Efficiency measurements were made for those test rulings that showed good groove characteristics: smoothness, proper ruling depth, and absence of defects. The intuitive feeling that higher grating efficiency should be correlated with the degree of smoothness of both the coating and the grating is supported by the results.

  8. Modulated optical solid-state spectrometer applications in plasma diagnostics

    Microsoft Academic Search

    John Howard

    1999-01-01

    A new electro-optically modulated optical solid-state (MOSS) interferometer has been constructed for the measurement of the low order spectral moments of line emission from optically thin radiant media. The instrument, which is based on the principle of the Fourier transform spectrometer, is rugged, compact, and inexpensive and offers a number of advantages over conventional grating based spectrometers. Most importantly, by

  9. Design Study of an Adaptive Optics Visual Echelle Spectrograph and Imager for the VLT

    E-print Network

    Design Study of an Adaptive Optics Visual Echelle Spectrograph and Imager for the VLT R study for an adaptive optics visual echelle spectrograph and imager/coronograph for use as parallel instrument of the Nasmyth Adaptive Optics System (NAOS) on unit UT3 (Melipal) of the VLT. The spectrograph

  10. Multidimensional spectrometer

    DOEpatents

    Zanni, Martin Thomas (Madison, WI); Damrauer, Niels H. (Boulder, CO)

    2010-07-20

    A multidimensional spectrometer for the infrared, visible, and ultraviolet regions of the electromagnetic spectrum, and a method for making multidimensional spectroscopic measurements in the infrared, visible, and ultraviolet regions of the electromagnetic spectrum. The multidimensional spectrometer facilitates measurements of inter- and intra-molecular interactions.

  11. CD Spectrometer

    NSDL National Science Digital Library

    Paul Doherty

    2000-01-01

    In this activity, learners use a compact disc to make a spectrometer, an instrument used to measure properties of light. Learners use their spectrometer to view a continuous spectrum produced by fluorescent light. This lesson guide also includes instructions on how to build a spectroscope from a cereal box.

  12. Transmission Grating Measurements of Undulator K

    SciTech Connect

    Bionta, R. M.

    2010-12-01

    This study was undertaken to understand the practicalities of determine K differences in the undulator modules by measuring single-shot x-ray spectra of the spontaneous radiation with a transmissive grating spectrometer under development to measure FEL spectra. Since the quality of the FEL is dependent on a uniform K value in all the undulator modules, being able to measure the relative undulator K values is important. Preliminary results were presented in a presentation, 'Use of FEL Off-Axis Zone Plate Spectrometer to Measure Relative K by the Pinhole/Centroid Method', at the 'LCLS Beam-Based Undulator K Measurements Workshop' on November 14, 2005 (UCRL-PRES-217281). This study applies equally well to reflective gratings of the appropriate period and inclinations.

  13. Renewable liquid reflection grating

    DOEpatents

    Ryutov, Dmitri D.; Toor, Arthur

    2003-10-07

    A renewable liquid reflection grating. Electrodes are operatively connected to a conducting liquid in an arrangement that produces a reflection grating and driven by a current with a resonance frequency. In another embodiment, the electrodes create the grating by a resonant electrostatic force acting on a dielectric liquid.

  14. Fiber Bragg gratings

    NASA Astrophysics Data System (ADS)

    Othonos, Andreas

    1997-12-01

    Since the discovery of photosensitivity in optical fibers there has been great interest in the fabrication of Bragg gratings within the core of a fiber. The ability to inscribe intracore Bragg gratings in these photosensitive fibers has revolutionized the field of telecommunications and optical fiber based sensor technology. Over the last few years, the number of researchers investigating fundamental, as well as application aspects of these gratings has increased dramatically. This article reviews the technology of Bragg gratings in optical fibers. It introduces the phenomenon of photosensitivity in optical fibers, examines the properties of Bragg gratings, and presents some of the important developments in devices and applications. The most common fabrication techniques (interferometric, phase mask, and point by point) are examined in detail with reference to the advantages and the disadvantages in utilizing them for inscribing Bragg gratings. Reflectivity, bandwidth, temperature, and strain sensitivity of the Bragg reflectors are examined and novel and special Bragg grating structures such as chirped gratings, blazed gratings, phase-shifted gratings, and superimposed multiple gratings are discussed. A formalism for calculating the spectral response of Bragg grating structures is described. Finally, devices and applications for telecommunication and fiber-optic sensors are described, and the impact of this technology on the future of the above areas is discussed.

  15. History of grating images

    Microsoft Academic Search

    Fujio Iwata

    2001-01-01

    Toppan Printing Co., Ltd. originated the name of 'grating image'. It means an image that consists of diffraction grating dots that look similar to the halftone dots of conventional printing. We proposed this new display method using simple gratings in order to enhance the visual effects when illumination is made by a fluorescent lamp. We considered the use of simple

  16. Catwalk grate lifting tool

    DOEpatents

    Gunter, L.W.

    1992-08-11

    A device is described for lifting catwalk grates comprising an elongated bent member with a handle at one end and a pair of notched braces and a hook at the opposite end that act in conjunction with each other to lock onto the grate and give mechanical advantage in lifting the grate. 10 figs.

  17. A soft x-ray fluorescence spectrometer at BESSY II

    NASA Astrophysics Data System (ADS)

    Follath, R.; Bischoff, P.; Eggenstein, F.; Noll, T.; Könnecke, R.; Schlappa, J.; Zeschke, T.

    2013-03-01

    A new spectrometer for resonant inelastic x-ray scattering experiments has been designed and is currently built at the synchrotron light facility BESSY II. The spectrometer with a total length of 3 m covers the photon energy range from 50 eV to 1000 eV with emphasis on the lower photon energy range. It is designed as plane grating spectrometer with two paraboloidal mirrors for collimation and focusing and a plane grating in-between. Two rotational degrees of freedom allow for a variation of the incidence and deflection angles at the grating. The geometrical acceptance of the spectrometer approaches a solid angle of 35 mrad × 40 mrad2 at low photon energies with a resolution better than 10 meV at 100 eV. A rotatable delay line detector is used to detect the fluorescence light in the line focus.

  18. Progress on characterization of a dualband IR imaging spectrometer

    Microsoft Academic Search

    Brian P. Beecken; Paul D. LeVan; Cory Lindh; Randall S. Johnson

    A dualband infrared focal plane array is the central component of a compact, low mass, multispectral imaging spectrometer with perfect spectral registration. The prototype spectrometer design uses a grating blaze chosen to be efficient over both 3.75-6.05 and 7.5-12.1µm, although the mercury cadmium telluride focal plane array limits the bandwidths with cutoff wavelengths near 5.2 and 10.5 µm. The spectrometer

  19. [Micro Hadamard transform near-infrared spectrometer].

    PubMed

    Zhang, Zhi-hai; Muo, Xiang-xia; Guo, Yuan-jun; Wang, Wei

    2011-07-01

    A new type micro Hadamard transform (HT) near-infrared (NIR) spectrometer is proposed in the present paper. It has a MOEMS (Micro-Opto-Electro-Mechanical Systems) blazed grating HT mask. It has merits of compactness, agility of dynamic mask generation and high scan speed. The structure and theory of this spectrometer are analyzed. The 63-order Hadamard-S matrix and mask are designed. The mask is dynamically generated by program of MOEMS blazed gratings. The spectrum is in agreement with that measured by Shimadzu spectrometer in experiments. It has a wavelength range between 900 and 1 700 nm, spectral resolution of 19 nm, single scan time of 2.4 s, SNR of 44.67:1, optical path of 70 mm x 130 mm, and weight under 1 kg. It can meet the requirement of real time detection and portable application. PMID:21942064

  20. Off-specular diffraction on periodic gratings studied by neutron reflectometry

    Microsoft Academic Search

    F. Ott; A. Menelle; C. Fermon; P. Humbert

    2000-01-01

    We present results of neutron diffraction on periodic gratings. The periodicities of the gratings range from 2 to 10?m. These experiments have been performed on the time-of-flight spectrometer EROS at the Laboratoire Léon Brillouin. We show that dynamical calculations (based on a matrix formalism) can quantitatively account for the results. Experiments have been performed on several systems (with various periodicities,

  1. Performance of the CHIRON high-resolution Echelle spectrograph

    NASA Astrophysics Data System (ADS)

    Schwab, Christian; Spronck, Julien F. P.; Tokovinin, Andrei; Szymkowiak, Andrew; Giguere, Matthew; Fischer, Debra A.

    2012-09-01

    CHIRON is a fiber-fed Echelle spectrograph with observing modes for resolutions from 28,000 to 120,000, built primarily for measuring precise radial velocities (RVs). We present the instrument performance as determined during integration and commissioning. We discuss the PSF, the effect of glass inhomogeneity on the cross-dispersion prism, temperature stabilization, stability of the spectrum on the CCD, and detector characteristics. The RV precision is characterized, with an iodine cell or a ThAr lamp as the wavelength reference. Including all losses from the sky to the detector, the overall efficiency is about 6%; the dominant limitation is coupling losses into the fiber due to poor guiding.

  2. History of grating images

    NASA Astrophysics Data System (ADS)

    Iwata, Fujio

    2001-06-01

    Toppan Printing Co., Ltd. originated the name of 'grating image'. It means an image that consists of diffraction grating dots that look similar to the halftone dots of conventional printing. We proposed this new display method using simple gratings in order to enhance the visual effects when illumination is made by a fluorescent lamp. We considered the use of simple gratings as elemental dots, and used a number of elemental dots to display a 2D image. This method produces an effect something like the halftone dots of printing. The grating image technology grows from its starting to become able to produce 3D images and a 3D-video system using an electron beam grating-writing system.

  3. Biopolymer holographic diffraction gratings

    Microsoft Academic Search

    Svetlana Savi? Ševi?; Dejan Pantelic

    2008-01-01

    Surface-relief diffraction gratings are holographically recorded in dextran sensitized with ammonium dichromate (DCD). DCD was exposed with single-frequency 200mW diode pumped ND-YAG laser, at 532nm. The diffraction grating profiles were analyzed by atomic force microscopy (AFM). It was found that different surface profiles could be obtained. Gratings with 330lines\\/mm spatial frequencies were made. Existence of higher harmonics in Fourier Transform

  4. Grating image technology

    NASA Astrophysics Data System (ADS)

    Iwata, Fujio

    1995-07-01

    The word 'grating image' was first named by Toppan Printing Company, Ltd. It means that an image consists of grating dots. In 1988, we presented this new technology at the Optical Security Systems Symposium, in Switzerland. Then it was improved and applied in display application. Recently, it was further applied in 3D video systems. In this report, the development history and the recent situations of grating image technology are described.

  5. Dual waveband compact catadioptric imaging spectrometer

    DOEpatents

    Chrisp, Michael P.

    2012-12-25

    A catadioptric dual waveband imaging spectrometer that covers the visible through short-wave infrared, and the midwave infrared spectral regions, dispersing the visible through shortwave infrared with a zinc selenide grating and midwave infrared with a sapphire prism. The grating and prism are at the cold stop position, enabling the pupil to be split between them. The spectra for both wavebands are focused onto the relevant sections of a single dual waveband detector. Spatial keystone distortion is controlled to less than one tenth of a pixel over the full wavelength range, facilitating the matching of the spectra in the midwave infrared with the shorter wavelength region.

  6. ISO observations of Titan with SWS/grating

    NASA Technical Reports Server (NTRS)

    Coustenis, A.; Encrenaz, T.; Salama, A.; Lellouch, E.; Gautier, D.; Kessler, M. F.; deGraauw, T.; Samuelson, R. E.; Bjoraker, G.; Orton, G.

    1997-01-01

    The observations of Titan performed by the Infrared Space Observatory (ISO) short wavelength spectrometer (SWS), in the 2 micrometer to 45 micrometer region using the grating mode, are reported on. Special attention is given to data from Titan concerning 7 micrometer to 45 micrometer spectral resolution. Future work for improving Titan's spectra investigation is suggested.

  7. Biopolymer holographic diffraction gratings

    NASA Astrophysics Data System (ADS)

    Savi? Ševi?, Svetlana; Panteli?, Dejan

    2008-03-01

    Surface-relief diffraction gratings are holographically recorded in dextran sensitized with ammonium dichromate (DCD). DCD was exposed with single-frequency 200 mW diode pumped ND-YAG laser, at 532 nm. The diffraction grating profiles were analyzed by atomic force microscopy (AFM). It was found that different surface profiles could be obtained. Gratings with 330 lines/mm spatial frequencies were made. Existence of higher harmonics in Fourier Transform of non-sinusoidal profiles shows that DCD is capable of recording spatial frequencies up to 1320 lines/mm (four times fundamental frequency). The measured maximum relief depth of the DCD grating is 402 nm.

  8. The diffraction grating in the Ivory optomechanical modeling tools

    NASA Astrophysics Data System (ADS)

    Hatheway, Alson E.

    2013-09-01

    In imaging spectrometers it is important that both the image of the far-field object and the image of the slit be stable on the detector plane. Lenses and mirrors contribute to the motions of these images but motions of the diffraction grating also have their own influences on these image motions. This paper develops the vector equations for the images (spectra) of the diffraction grating and derives their optomechanical influence coefficients from them. The Ivory Optomechanical Modeling Tools integrates the diffraction grating into the larger optical imaging system and formats the whole system's influence coefficients suitably for both spreadsheet and finite element analysis methods. Their application is illustrated in an example of a spectrometer exposed to both static and dynamic disturbances.

  9. Novel wavelength-dispersive X-ray fluorescence spectrometer

    NASA Astrophysics Data System (ADS)

    Firsov, A.; Erko, A.; Senf, F.; Rehanek, J.; Brzhezinskaya, M.; Wernet, R. Mitzner Ph; Föhlisch, A.

    2013-03-01

    A new spectrometer, utilizing a reflection zone plate based grating, for the Mn L fluorescence line was recently designed, manufactured and tested at Helmholtz Zentrum Berlin. The angular acceptance of the grating is ~0.011 rad2 the absolute efficiency at 640 eV is 16%, and the energy resolution, for a detector slit size of 120 ?m and in simultaneous spectra registration mode, is about ?/?? ~ 100 FWHM.

  10. ORFEUS II echelle spectra: H_2 absorption in SMC gas

    NASA Astrophysics Data System (ADS)

    Richter, P.; Widmann, H.; de Boer, K. S.; Appenzeller, I.; Barnstedt, J.; Goelz, M.; Grewing, M.; Gringel, W.; Kappelmann, N.; Kraemer, G.; Mandel, H.; Werner, K.

    We present a study of H_2 in the SMC gas, based on space shuttle Far UV spectroscopy with ORFEUS and the Tue/HD echelle spectrograph, in the line of sight to the SMC star HD 5980. 17 absorption lines from the Lyman band have been analysed. Our line of sight crosses two clouds within the SMC. We detect a cool molecular component near +120 km s^{-1}, where the H_2 from the lowest 3 rotational states (J <= 2) is found. For this cloud we derive an excitation temperature of ~= 70 K, probably the kinetic temerature of the gas. The cloud is located in the SMC foreground. Another SMC component is visible at +160 km s^{-1}. Here we find unblended H_2 absorption lines from levels 5 <= J <= 7. For this component we obtain an equivalent excitation temperature Tex > 2350 K and conclude that this cloud must be highly excited by strong UV radiation from its energetic environment. (Research supported in part by the DARA)

  11. Grating image technology

    Microsoft Academic Search

    Fujio Iwata

    1995-01-01

    The word 'grating image' was first named by Toppan Printing Company, Ltd. It means that an image consists of grating dots. In 1988, we presented this new technology at the Optical Security Systems Symposium, in Switzerland. Then it was improved and applied in display application. Recently, it was further applied in 3D video systems. In this report, the development history

  12. Long-Wave Infrared Dyson Spectrometer

    NASA Technical Reports Server (NTRS)

    Johnson, William R.; Hook, Simon J.; Mouroulis, Pantazis Z.; Wilson, Daniel W.; Gunapala, Sarath D.; Hill, Cory J.; Mumolo, Jason M.; Eng, Bjorn T.

    2008-01-01

    Preliminary results are presented for an ultra compact long-wave infrared slit spectrometer based on the dyson concentric design. The dyson spectrometer has been integrated in a dewar environment with a quantum well infrared photodetecor (QWIP), concave electron beam fabricated diffraction grating and ultra precision slit. The entire system is cooled to cryogenic temperatures to maximize signal to noise ratio performance, hence eliminating thermal signal from transmissive elements and internal stray light. All of this is done while maintaining QWIP thermal control. A general description is given of the spectrometer, alignment technique and predicated performance. The spectrometer has been designed for optimal performance with respect to smile and keystone distortion. A spectral calibration is performed with NIST traceable targets. A 2-point non-uniformity correction is performed with a precision blackbody source to provide radiometric accuracy. Preliminary laboratory results show excellent agreement with modeled noise equivalent delta temperature and detector linearity over a broad temperature range.

  13. Imaging IR spectrometer, phase 2

    NASA Technical Reports Server (NTRS)

    Gradie, Jonathan; Lewis, Ralph; Lundeen, Thomas; Wang, Shu-I

    1990-01-01

    The development is examined of a prototype multi-channel infrared imaging spectrometer. The design, construction and preliminary performance is described. This instrument is intended for use with JPL Table Mountain telescope as well as the 88 inch UH telescope on Mauna Kea. The instrument is capable of sampling simultaneously the spectral region of 0.9 to 2.6 um at an average spectral resolution of 1 percent using a cooled (77 K) optical bench, a concave holographic grating and a special order sorting filter to allow the acquisition of the full spectral range on a 128 x 128 HgCdTe infrared detector array. The field of view of the spectrometer is 0.5 arcsec/pixel in mapping mode and designed to be 5 arcsec/pixel in spot mode. The innovative optical design has resulted in a small, transportable spectrometer, capable of remote operation. Commercial applications of this spectrometer design include remote sensing from both space and aircraft platforms as well as groundbased astronomical observations.

  14. Progress on characterization of a dualband IR imaging spectrometer

    Microsoft Academic Search

    Brian P. Beecken; Paul D. LeVan; Cory Lindh; Randall S. Johnson

    2008-01-01

    A dualband infrared focal plane array is the central component of a compact, low mass, multispectral imaging spectrometer with perfect spectral registration. The prototype spectrometer design uses a grating blaze chosen to be efficient over both 3.75-6.05 and 7.5-12.1 mum, although the mercury cadmium telluride focal plane array limits the bandwidths with cutoff wavelengths near 5.2 and 10.5 mum. The

  15. Automatic one dimensional spectra extraction for Weihai fiber-fed high resolution echelle spectra

    NASA Astrophysics Data System (ADS)

    Hu, Shao Ming; Gao, Dong Yang

    2014-11-01

    One fiber-fed high resolution echelle spectrograph was built for the one meter telescope atWeihai Observatory of Shandong University. It is used for exoplanet searching by radial velocity method and for stellar spectra analysis. One dimensional spectra extraction from the raw echelle data is researched in this paper. Flat field images with different exposure times were used to trace the order position accurately. The accurate background was fitted from each CCD image and it was subtracted from the raw image to correct the background and straylight. The intensity of each order decreases towards the order margin, and the lengths of order are different between the blue and red regions. The order tracing during the data reduction was investigated in this work. Accurate flux can be obtained after considering the effects of bad pixels, the curvature of each order and so on. One Interactive Data Language program for one dimensional spectra extraction was adopted and implemented to echelle data reduction for Weihai fiber-fed high resolution echelle spectra, and the results are illustrated here. The program is efficient and accurate for echelle data reduction. It can be adopted to reduce data taken by other instruments even the spectrographs in other fields, and it is very convenient for astronomers.

  16. IP Pegasi in outburst: Echelle spectroscopy & Modulation Doppler Tomography

    E-print Network

    C. Papadaki; H. M. J. Boffin; D. Steeghs

    2008-07-02

    We analyse a unique set of time-resolved echelle spectra of the dwarf nova IP Peg, obtained at ESO's NTT with EMMI. The dataset covers the wavelength range of 4000-7500A and shows Balmer, HeI, HeII and heavier elements in emission. IP Peg was observed one day after the peak of an outburst. The trailed spectra, spectrograms and Doppler maps show characteristics typical of IP Pegasi during the early stages of its outburst. The high-ionisation line of HeII 4686A is the most centrally located line and has the greatest radial extension compared to the HeI lines. The Balmer lines extend from close to the white dwarf up to approximately 0.45 times R_L, with the outer radius gradually increasing when moving from H delta to H alpha. The application, for the first time, of the modulation Doppler tomography technique, maps any harmonically varying components present in the system configuration. We find, as expected, that part of the strong secondary star emission in Balmer and HeI lines is modulated predominantly with the cosine term, consistent with the emission originating from the irradiated front side of the mass-donor star, facing the accreting white dwarf. For the Balmer lines the level of the modulation, compared to the average emission, decreases when moving to higher series. Emission from the extended accretion disk appears to be only weakly modulated, with amplitudes of at most a few percent of the non-varying disk emission. We find no evidence of modulated emission in the spiral arms, which if present, is relatively weak at that our signal-to-noise ratio was good enough to put a lower detection limit of any modulated emission at 5--6%. Only in one arm of the HeII 4686A line, is there a possibility of modulated emission, but again, we cannot be sure this is not caused by blending with the nearby Bowen complex of lines.

  17. Monolithic micro-spectrometer for low-cost sensing in materials processing

    Microsoft Academic Search

    C. M. Egert; S. Rajic

    1997-01-01

    We have developed a monolithic micro-spectrometer suitable for a variety of sensing applications including industrial process monitoring. The device consists of a solid structure with a volume less than 6 cubic centimeters. All optical components of the spectrometer including two aspheric mirrors, a diffraction grating, and entrance and exit surfaces are fabricated onto the surface of the structure. All light

  18. Adapting a very high resolution echelle spectrograph to an 8 meter class telescope

    NASA Astrophysics Data System (ADS)

    Reynolds, Robert O.; Dettmann, Lee

    2014-07-01

    The Adaptively Corrected Echelle Spectrograph (ACES) high resolution echelle spectrograph was originally developed at Steward Observatory to couple adaptively-corrected stellar images to the instrument using a near single mode optical fiber to give R~190,000 at V band. We explore here the feasibility of using the spectrograph with the 2x8.4m Large Binocular Telescope (LBT), preserving the fiber coupling for instrument isolation and illumination stability, but employing either a narrow slit or image slicer to offset the smaller component size and thereby preserve high resolution. Such a combination could offer simultaneously higher resolution with greater wavelength coverage per exposure than the configuration of alternate instruments.

  19. Developing Tools for Undergraduate Spectroscopy: An Inexpensive Visible Light Spectrometer

    ERIC Educational Resources Information Center

    Vanderveen, Jesse R.; Martin, Brian; Ooms, Kristopher J.

    2013-01-01

    The design and implementation of an inexpensive, high-resolution Littrow-type visible light spectrometer is presented. The instrument is built from low-cost materials and interfaced with the program RSpec for real-time spectral analysis, making it useful for classroom and laboratory exercises. Using a diffraction grating ruled at 1200 lines/mm and…

  20. A Rowland Circle, multielement graphite furnace atomic absorption spectrometer

    Microsoft Academic Search

    Karl A. Wagner; James D. Batchelor; Bradley T. Jones

    1998-01-01

    A simultaneous, multielement atomic absorption spectrometer utilizing a graphite furnace atomizer was constructed and evaluated. The optical arrangement employs a concave grating to combine the spectral output from a deuterium lamp and four hollow cathode lamps that are placed on the perimeter of a Rowland Circle. A graphite furnace atomizer is positioned on the circle at the point of convergence

  1. Off-specular diffraction on periodic gratings studied by neutron reflectometry

    NASA Astrophysics Data System (ADS)

    Ott, F.; Menelle, A.; Fermon, C.; Humbert, P.

    2000-06-01

    We present results of neutron diffraction on periodic gratings. The periodicities of the gratings range from 2 to 10 ?m. These experiments have been performed on the time-of-flight spectrometer EROS at the Laboratoire Léon Brillouin. We show that dynamical calculations (based on a matrix formalism) can quantitatively account for the results. Experiments have been performed on several systems (with various periodicities, materials and structures) to study the diffraction efficiency effects. We show that optimised gratings can exhibit diffraction efficiencies as high as 30% over a scattering wave-vector range 0< qz<0.2 nm -1. We suggest that such gratings could be used as a neutron energy analyser especially well suited for time-of-flight spectrometers.

  2. Degradation Free Spectrometers for Solar EUV Measurements

    NASA Astrophysics Data System (ADS)

    Wieman, S. R.; Didkovsky, L. V.; Judge, D. L.; McMullin, D. R.

    2011-12-01

    Solar EUV observations will be made using two new degradation-free EUV spectrometers on a sounding rocket flight scheduled for summer 2012. The two instruments, a rare gas photoionization-based Optics-Free Spectrometer (OFS) and a Dual Grating Spectrometer (DGS), are filter-free and optics-free. OFS can measure the solar EUV spectrum with a spectral resolution comparable to that of grating-based EUV spectrometers. The DGS selectable spectral bandwidth is designed to provide solar irradiance in a 10 nm band centered on the Lyman-alpha 121.6 nm line and a 4 nm band centered on the He-II 30.4 nm line to overlap EUV observations from the SDO/EUV Variability Experiment (EVE) and the SOHO/Solar EUV Monitor (SEM). A clone of the SOHO/SEM flight instrument and a Rare Gas Ionization Cell (RGIC) absolute EUV detector will also be flown to provide additional measurements for inter-comparison. Program delays related to the sounding rocket flight termination system, which was no longer approved by the White Sands Missile Range prevented the previously scheduled summer 2011 launch of these instruments. During this delay several enhancements have been made to the sounding rocket versions of the DFS instruments, including a lighter, simplified vacuum housing and gas system for the OFS and an improved mounting for the DGS, which allows more accurate co-alignment of the optical axes of the DGS, OFS, and the SOHO/SEM clone. Details of these enhancements and results from additional lab testing of the instruments are reported here. The spectrometers are being developed and demonstrated as part of the Degradation Free Spectrometers (DFS) project under NASA's Low Cost Access to Space (LCAS) program and are supported by NASA Grant NNX08BA12G.

  3. Nanofabrication advances for high efficiency critical-angle transmission gratings

    NASA Astrophysics Data System (ADS)

    Bruccoleri, Alexander R.; Guan, Dong; Heilmann, Ralf K.; Vargo, Steve; DiPiazza, Frank; Schattenburg, Mark L.

    2013-09-01

    We report several break-through nanofabrication developments enabling high efficiency and high resolving power spectrometers in the soft x-ray band. The device is the critical-angle transmission (CAT) grating, which combines the low mass and relaxed alignment tolerances of a transmission grating with the high broad-band efficiency and high diffraction orders of a blazed reflection grating. Past work successfully demonstrated the CAT grating concept; however, the open-area fraction was often less than 20% whilst more than 50% is desired. This presents numerous nanofabrication challenges including a requirement for a freestanding silicon membrane of ultra high-aspect ratio bars at a period of 200 nanometers with minimal cross support blockage. Furthermore, the sidewalls must be smooth to a few nanometers to efficiently reflect soft x-rays. We have developed a complete nanofabrication process for creating freestanding CAT gratings via plasma-etching silicon wafers with a buried layer of SiO2. This removable buried layer enables combining a record-performance plasma etch for the CAT grating with a millimeter-scale honeycomb structural support to create a large-area freestanding membrane. We have also developed a process for polishing sidewalls of plasma-etched ultra-high aspect ratio nanoscale silicon structures via potassium hydroxide (KOH). This process utilizes the anisotropic etch nature of single crystal silicon in KOH. We developed a novel alignment technique to align the CAT grating bars to the {111} planes of silicon within 0.2 degrees, which enables KOH to etch away sidewall roughness without destroying the structure, since the {111} planes etch approximately 100 times slower than the non-{111} planes. Preliminary results of a combined freestanding grating with polishing are presented to enable efficient diffraction of soft x-rays.

  4. Thermomechanical modification of diffraction gratings

    NASA Astrophysics Data System (ADS)

    Sumetsky, M.; Dulashko, Y.; Fleming, J. W.; Kortan, A.; Reyes, P. I.; Westbrook, P. S.

    2004-06-01

    The most accurate approaches to fabrication of diffraction gratings are known to be the lithographic and holographic methods. The lithographic methods allow fabrication of arbitrarily chirped gratings whose performance, however, is degraded by stitching errors. The holographic methods are free from stitching errors; however, they are limited in the achievable spatial variations of their grating periods. We suggest a method of diffraction grating modification by nonuniform heating and stretching that is much more flexible than the holographic approach and does not suffer from the problem of stitching error. We demonstrate our approach for quartz phase masks that have a characteristic grating period of 1 µm and a length of several centimeters. Our approach allows the grating periods of the phase masks to vary in a range from a few picometers to a few nanometers and a spatial resolution of a few millimeters. It is shown that the grating period can be modified with a negligible effect on the profile of the gratings.

  5. Echelle Spectroscopy of the NA i D Absorption-Line Systems of Markarian 231

    Microsoft Academic Search

    Karl Forster; R. Michael Rich; James K. McCarthy

    1995-01-01

    We have obtained echelle spectra of the nucleus of Markarian 231 in 1991 and 1994 and modeled the profiles of the sodium absorption lines that are blueshifted up to 7800 km s-1 less than the systemic recession velocity of this active galactic nucleus (AGN). We find that the broadest absorption line (system I) can best be fitted with a blend

  6. Birefringence Bragg Binary (3B) grating, quasi-Bragg grating and immersion gratings

    NASA Astrophysics Data System (ADS)

    Ebizuka, Noboru; Morita, Shin-ya; Yamagata, Yutaka; Sasaki, Minoru; Bianco, Andorea; Tanabe, Ayano; Hashimoto, Nobuyuki; Hirahara, Yasuhiro; Aoki, Wako

    2014-07-01

    A volume phase holographic (VPH) grating achieves high angular dispersion and very high diffraction efficiency for the first diffraction order and for S or P polarization. However the VPH grating could not achieve high diffraction efficiency for non-polarized light at a large diffraction angle because properties of diffraction efficiencies for S and P polarizations are different. Furthermore diffraction efficiency of the VPH grating extinguishes toward a higher diffraction order. A birefringence binary Bragg (3B) grating is a thick transmission grating with optically anisotropic material such as lithium niobate or liquid crystal. The 3B grating achieves diffraction efficiency up to 100% for non-polarized light by tuning of refractive indices for S and P polarizations, even in higher diffraction orders. We fabricated 3B grating with liquid crystal and evaluated the performance of the liquid crystal grating. A quasi-Bragg (QB) grating, which consists long rectangle mirrors aligned in parallel precisely such as a window shade, also achieves high diffraction efficiency toward higher orders. We fabricated QB grating by laminating of silica glass substrates and glued by pressure fusion of gold films. A quasi-Bragg immersion (QBI) grating has smooth mirror hypotenuse and reflector array inside the hypotenuse, instead of step-like grooves of a conventional immersion grating. An incident beam of the QBI grating reflects obliquely at a reflector, then reflects vertically at the mirror surface and reflects again at the same reflector. We are going to fabricate QBI gratings by laminating of mirror plates as similar to fabrication of the QB grating. We will also fabricate silicon and germanium immersion gratings with conventional step-like grooves by means of the latest diamond machining methods. We introduce characteristics and performance of these gratings.

  7. Circular Fibonacci gratings.

    PubMed

    Gao, Nan; Zhang, Yuchao; Xie, Changqing

    2011-11-01

    We introduce circular Fibonacci gratings (CFGs) that combine the concept of circular gratings and Fibonacci structures. Theoretical analysis shows that the diffraction pattern of CFGs is composed of fractal distributions of impulse rings. Numerical simulations are performed with two-dimensional fast Fourier transform to reveal the fractal behavior of the diffraction rings. Experimental results are also presented and agree well with the numerical results. The fractal nature of the diffraction field should be of great theoretical interest, and shows potential to be further developed into practical applications, such as in laser measurement with wideband illumination. PMID:22086040

  8. Compact slanted grating couplers

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Jiang, Jianhua; Nordin, Gregory P.

    2004-07-01

    We present a compact and efficient design for slanted grating couplers (SLGC's) to vertically connect fibers and planar waveguides without intermediate optics. The proposed SLGC employs a strong index modulated slanted grating. With the help of a genetic algorithm-based rigorous design tool, a 20 ?m-long SLGC with 80.1% input coupling efficiency has been optimized. A rigorous mode analysis reveals that the phase-matching condition and Bragg condition are satisfied simultaneously with respect to the fundamental leaky mode supported by the optimized SLGC.

  9. Charged particle accelerator grating

    DOEpatents

    Palmer, Robert B. (Shoreham, NY)

    1986-01-01

    A readily disposable and replaceable accelerator grating for a relativistic particle accelerator. The grating is formed for a plurality of liquid droplets that are directed in precisely positioned jet streams to periodically dispose rows of droplets along the borders of a predetermined particle beam path. A plurality of lasers are used to direct laser beams into the droplets, at predetermined angles, thereby to excite the droplets to support electromagnetic accelerating resonances on their surfaces. Those resonances operate to accelerate and focus particles moving along the beam path. As the droplets are distorted or destroyed by the incoming radiation, they are replaced at a predetermined frequency by other droplets supplied through the jet streams.

  10. New optical systems for holographic recordings of aberration-corrected diffraction gratings

    NASA Astrophysics Data System (ADS)

    Sokolova, Elena A.

    2001-01-01

    A spherical concave diffraction grating was chosen as the dispersing element for a number of spectroscopic deices. More recent application of these grating is designing of multiplexers/demultiplexers for wavelength routed optical networks. Concave grating acts as the focusing element and can be the sole optical element of a device, which simplifies its adjustment and increases the transmittance. However, it possesses aberrations. Conventional method of concave diffraction grating recording using interference of two spherical waves formed using dividing an depending of laser beam, gives possibility to minimize three main types of aberrations, the defocusing, the meridional coma and the first order astigmatism. For the wide range of spectrometers these gratings can be used with rather good results. However, if we want to design spectrometer with increased aperture, wide spectral region or extremely high resolving power, we have to take into consideration per limit more than two aberrations - the sagittal coma and the spherical aberration. We also have this problem in designing of wavelength routers, where aberration geometric size of image should be not more than the optical fiber diameter. We can resolve this problem using aspheric wavefront recording systems. Since refraction optics is not good for holographic recording because of scattering, this system can include mirrors or other diffraction gratings. In present work different recording systems are discussed from the point of view of geometric theory of grating and from the point of view of reality of experimental installing and using of these systems as well.

  11. Gratings and waveguides

    NASA Technical Reports Server (NTRS)

    Bates, K. A.; Erwin, J. K.; Li, L.; Burke, J. J.; Ramanujam, N.

    1993-01-01

    Our immediate objective is to understand the limitations of guided-wave and grating coupler devices in their application to optical data storage. Our long-range goal is to develop and validate design codes for integrated optic devices. The principal research activity was in the development of numerical models for the design of a blue wavelength integrated optical source for data storage applications.

  12. Silicon graphene Bragg gratings

    NASA Astrophysics Data System (ADS)

    Capmany, José; Domenech, David; Muñoz, Pascual

    2014-03-01

    We propose the use of interleaved graphene sections on top of a silicon waveguide to implement tunable Bragg gratings. The filter central wavelength and bandwidth can be controlled changing the chemical potential of the graphene sections. Apodization techniques are also presented.

  13. Silicon graphene Bragg gratings.

    PubMed

    Capmany, José; Domenech, David; Muñoz, Pascual

    2014-03-10

    We propose the use of interleaved graphene sections on top of a silicon waveguide to implement tunable Bragg gratings. The filter central wavelength and bandwidth can be controlled changing the chemical potential of the graphene sections. Apodization techniques are also presented. PMID:24663869

  14. High-efficiency blazed transmission gratings for high-resolution soft x-ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Heilmann, Ralf K.; Bruccoleri, Alexander R.; Schattenburg, Mark L.

    2015-01-01

    High-resolution spectroscopy of astrophysical sources is the key to gaining a quantitative understanding of the history, dynamics, and current conditions of the cosmos. A large-area (> 1,000 cm2), high resolving power (R = ?/?? > 3,000) soft x-ray spectrometer that covers the lines of C, N, O, Ne and Fe ions is the ideal tool to address a number of high-priority sciences questions from the 2010 Decadal Survey, such as the connection between super-massive black holes and large-scale structure via cosmic feedback, the evolution of large-scale structure, the behavior of matter at high densities, and the conditions close to black holes. Numerous mission concepts that meet these requirements have been studied and proposed over the last few years, including grating instruments for the International X-ray Observatory. Nevertheless, no grating missions are currently approved. To improve the chances for future soft x-ray grating spectroscopy missions, grating technology has to progress and be advanced to higher TRLs. We have developed Critical-Angle Transmission (CAT) gratings that combine the advantages of blazed reflection gratings (high efficiency, use of higher diffraction orders) with those of conventional transmission gratings (low mass, relaxed alignment tolerances and temperature requirements, transparent at higher energies). A CAT grating-based spectrometer can provide performance 1-2 orders of magnitude better than current grating instruments on Chandra and Newton-XMM with minimal resource requirements. We have fabricated large-area free-standing CAT gratings with minimal integrated support structures from silicon-on-insulator wafers using advanced lithography and a combination of deep reactive-ion and wet etching, and will present our latest x-ray test results showing record high diffraction efficiencies in blazed orders.

  15. Research directed toward improved echelles for the ultraviolet. [large space teslescope spectrographs

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Low frequency gratings obtainable with present technology, can meet the grating-efficiency design goals for potential space telescope spectrographs. Gratings made with changes in the three specific parameters: the ruling tool profile, the coating material, and the lubricants used during the ruling process were compared. A series of coatings and test gratings were fabricated and were examined for surface smoothness with a Nomarski differential interference microscope and an electron microsocope. Photomicrographs were obtained to show the difference in smoothness of the various coatings and rulings. Efficiency measurements were made for those test rulings that showed good groove characteristics: smoothness, proper ruling depth, and absence of defects (e.g., streaks, feathered edges and rough sides). Higher grating efficiency should be correlated with the degree of smoothness of both the coating and the grating groove.

  16. First application close measurements applying the new hybrid integrated MEMS spectrometer

    NASA Astrophysics Data System (ADS)

    Grüger, Heinrich; Pügner, Tino; Knobbe, Jens; Schenk, Harald

    2013-05-01

    Grating spectrometers have been designed in many different configurations. Now potential high volume applications ask for extremely miniaturized and low cost systems. By the use of integrated MEMS (micro electro mechanical systems) scanning grating devices a less expensive single detector can be used in the NIR instead of the array detectors required for fixed grating systems. Meanwhile the design of a hybrid integrated MEMS scanning grating spectrometer has been drawn. The MEMS device was fabricated in the Fraunhofer IPMS own clean room facility. This chip is mounted on a small circuit board together with the detector and then stacked with spacer and mirror substrate. The spectrometer has been realized by stacking several planar substrates by sophisticated mounting technologies. The spectrometer has been designed for the 950nm - 1900nm spectral range and 9nm spectral resolution with organic matter analysis in mind. First applications are considered in the food quality analysis and food processing technology. As example for the use of a spectrometer with this performance the grill process of steak was analyzed. Similar measurement would be possible on dairy products, vegetables or fruit. The idea is a mobile spectrometer for in situ and on site analysis applications in or attached to a host system providing processing, data access and input-output capabilities, disregarding this would be a laptop, tablet, smart phone or embedded platform.

  17. Multichannel grazing-incidence spectrometer for plasma impurity diagnosis: SPRED.

    PubMed

    Fonck, R J; Ramsey, A T; Yelle, R V

    1982-06-15

    A compact vacuum ultraviolet spectrometer system has been developed to provide time-resolved impurity spectra from tokamak plasmas. Two interchangeable aberration-corrected toroidal diffraction gratings with flat focal fields provide simultaneous coverage over the ranges 100-1100 A or 160-1700 A. The detector is an intensified self-scanning photodiode array. Spectral resolution is 2 A with the higher dispersion grating. Minimum readout time for a full spectrum is 20 msec, but up to seven individual spectral lines can be measured with a 1-msec time resolution. The sensitivity of the system is comparable with that of a conventional grazing-incidence monochromator. PMID:20395992

  18. The Berkeley EUV spectrometer for ORFEUS

    NASA Technical Reports Server (NTRS)

    Hurwitz, M.; Bowyer, S.

    1991-01-01

    A novel EUV spectrometer is presented for the ORFEUS-SPAS mission. It uses a set of four varied line-space spherical diffraction gratings to obtain high-resolution spectra of point sources at wavelengths between 390 and 1200 A. The spectra are recorded with two detector units, each containing curved-surface microchannel plates and a delay-line anode-readout system. An independent optical system detects the image of the source in the entrance aperture and tracks the source as it drifts during an observation, enabling a reconstruction of the spectra postflight. The overall system performance is discussed and illustrated by synthetic spectra.

  19. Charged particle accelerator grating

    DOEpatents

    Palmer, R.B.

    1985-09-09

    A readily disposable and replaceable accelerator grating for a relativistic particle accelerator is described. The grating is formed for a plurality of liquid droplets that are directed in precisely positioned jet streams to periodically dispose rows of droplets along the borders of a predetermined particle beam path. A plurality of lasers are used to direct laser beams onto the droplets, at predetermined angles, thereby to excite the droplets to support electromagnetic accelerating resonances on their surfaces. Those resonances operate to accelerate and focus particles moving along the beam path. As the droplets are distorted or destroyed by the incoming radiation, they are replaced at a predetermined frequency by other droplets supplied through the jet streams.

  20. Elemental abundances for HgMn stars observed with EBASIM echelle spectrograph at CASLEO

    NASA Astrophysics Data System (ADS)

    Pintado, Olga I.; Adelman, Saul J.

    2004-12-01

    Elemental abundance analysis are derived for the Mercury-Manganese stars HR 4817 (B8 II/III) and ? Lep (B9 IV) using CCD recorded exposures obtained at the EBASIM echelle spectrograph at the 2.1-m CASLEO (Complejo Astronómico El Leoncito) telescope in Argentina. The spectra coverage is 390-900 nm. The results are compared with previous analyses made with spectra taken using the REOSC echelle spectrograph at CASLEO, the coudé feed telescope at Kitt Peak National Observatory, and/or with the Dominion Astrophysical Observatory coudé spectrograph. As these new spectra go farther into the red and have better resolution than those obtained with the REOSC, we could make better abundance determinations.

  1. SCORE: A Mid-Infrared Echelle Format Spectrograph with No Moving Parts

    Microsoft Academic Search

    Jeffrey Van Cleve; G. E. Gull; S. A. Rinehart; J. D. Smith; J. C. Wilson; J. R. Houck; Mike Colonno; R. Brown; W. Blalock

    1998-01-01

    SCORE (SIRTF Cornell Echelle) is a mid-infrared spectrograph with a resolution of lambda\\/Deltalambda=600 covering the entire ground-based 10 mum atmospheric window in a single exposure. It was built as a proof of concept for one of the SIRTF (Space Infrared Telescope Facility) instruments. It has no moving mechanical parts. SCORE was designed to operate properly upon assembly needing nothing more

  2. Grating-structured metallic microsprings.

    PubMed

    Huang, Tao; Liu, Zhaoqian; Huang, Gaoshan; Liu, Ran; Mei, Yongfeng

    2014-08-21

    We fabricate grating-structured metallic microsprings with well-defined helical angles and diameters, which are self-rolled from strained nanomembranes patterned with gratings. The grating structures on the metal membrane, replicated from the imprinted polymer layer beneath, give rise to the controlled rolling direction after selective etching of the underlying sacrificial layer. The rolling direction of the grating-structured thin metal film is always perpendicular to the long side edge of gratings, offering a good way to roll up strained strips into well controlled three-dimensional (3D) microsprings simply by altering the dimension and orientation of the structured strips. The mechanical elasticity of these grating-structured metallic microsprings is verified for the potential application as a flow rate sensor. Our work may stimulate rigorous synthesis of highly functional and complex 3D helical micro and nanostructures, and hint a broad range of applications such as environmental sensors, micro-/nanoscale robots, metamaterials, etc. PMID:24728100

  3. Dds-Based Fast Scan Spectrometer

    NASA Astrophysics Data System (ADS)

    Alekseev, E. A.; Motiyenko, R. A.; Margulès, L.

    2010-06-01

    The technique of direct digital synthesis (DDS) has two important features which enable its application in microwave spectroscopy: micro-Hz tuning resolution and extremely fast frequency switching with continuous phase. We have applied a direct digital synthesizer in a PLL-spectrometer based on backward-wave oscillator (BWO). As result we have obtained an instrument that can cover a 100 GHz bandwidth in less than one hour with high spectral resolution and high precision of frequency measurement. The application of the spectrometer to sub-millimeter wave survey spectra records of several isotopic species of astrophysical molecules (methanol, formamide, methyl formate, aziridine) will be discussed. The support of Université de Lille 1 and le Programme National de Physique Chimie du Milieu Interstellaire is gratefully acknowledged.

  4. Analytical design of an Offner imaging spectrometer

    NASA Astrophysics Data System (ADS)

    Prieto-Blanco, X.; Montero-Orille, C.; Couce, B.; de La Fuente, R.

    2006-10-01

    We present the analytical design of an imaging spectrometer based on the three-concentric-mirror (Offner) configuration. The approach presented allows for the rapid design of this class of system. Likewise, high-optical-quality spectrometers are obtained without the use of aberration-corrected gratings, even for high speeds. Our approach is based on the calculation of both the meridional and the sagittal images of an off-axis object point. Thus, the meridional and sagittal curves are obtained in the whole spectral range. Making these curves tangent to each other for a given wavelength results in a significant decrease in astigmatism, which is the dominant residual aberration.RMS spot radii less than 5 mm are obtained for speeds as high as f/2.5 and a wavelength range of 0.4-1.0 µm. A design example is presented using a free interactive optical design tool.

  5. Virtual long-period gratings.

    PubMed

    Jáuregui, César; López-Higuera, José Miguel

    2005-01-01

    A theoretical prediction of a new fiber grating structure is presented. This new device is achieved when a high-birefringence fiber is heavily twisted. It behaves like a long-period grating, but its spectral response can be controlled with the input state of polarization of the light. Since there is no permanent index change, but the index change is instead a product of the polarization evolution along the fiber, this device is called a virtual long-period grating. PMID:15648622

  6. The spectral image acquisition and processing system based on folded gratings spectrograph and ICCD

    Microsoft Academic Search

    Yunfeng Bi; Fujun Qi; Jinjia Guo; Ronger Zheng

    2011-01-01

    A spectral image acquisition and processing system based on a commercial available ICCD camera which has an internal Digital Delay Generator module and a purpose-built folded gratings spectrometer without movable parts internally was built up to fulfill the wide wavelength coverage, high spectral resolution and time-resolved detection requirement in oceanic environment. In this system, the spectral information is contained in

  7. Flat field concave holographic grating with broad spectral region and moderately high resolution.

    PubMed

    Wu, Jian Fen; Chen, Yong Yan; Wang, Tai Sheng

    2012-02-01

    In order to deal with the conflicts between broad spectral region and high resolution in compact spectrometers based on a flat field concave holographic grating and line array CCD, we present a simple and practical method to design a flat field concave holographic grating that is capable of imaging a broad spectral region at a moderately high resolution. First, we discuss the principle of realizing a broad spectral region and moderately high resolution. Second, we provide the practical method to realize our ideas, in which Namioka grating theory, a genetic algorithm, and ZEMAX are used to reach this purpose. Finally, a near-normal-incidence example modeled in ZEMAX is shown to verify our ideas. The results show that our work probably has a general applicability in compact spectrometers with a broad spectral region and moderately high resolution. PMID:22307123

  8. Normal incidence spectrophotometer using high density transmission grating technology and highly efficiency silicon photodiodes for absolute solar EUV irradiance measurements

    NASA Technical Reports Server (NTRS)

    Ogawa, H. S.; Mcmullin, D.; Judge, D. L.; Korde, R.

    1992-01-01

    New developments in transmission grating and photodiode technology now make it possible to realize spectrometers in the extreme ultraviolet (EUV) spectral region (wavelengths less than 1000 A) which are expected to be virtually constant in their diffraction and detector properties. Time dependent effects associated with reflection gratings are eliminated through the use of free standing transmission gratings. These gratings together with recently developed and highly stable EUV photodiodes have been utilized to construct a highly stable normal incidence spectrophotometer to monitor the variability and absolute intensity of the solar 304 A line. Owing to its low weight and compactness, such a spectrometer will be a valuable tool for providing absolute solar irradiance throughout the EUV. This novel instrument will also be useful for cross-calibrating other EUV flight instruments and will be flown on a series of Hitchhiker Shuttle Flights and on SOHO. A preliminary version of this instrument has been fabricated and characterized, and the results are described.

  9. Spectrometer for monitoring of atmospheric ozone (ozonometer)

    NASA Astrophysics Data System (ADS)

    Dobrolenskiy, Yury; Korablev, Oleg; Ionov, Dmitry; Viazovetskiy, Nikita; Tchikov, Konstantin; Krasavtsev, Valery; Moiseev, Pavel; Belyaev, Denis; Fedorova, Anna; Mantsevich, Sergey; Zhirnova, Yulia; Rumyantsev, Dmitry; Kananykhin, Igor; Viktorov, Alexey; Shatalov, Andrey; Zherebtsov, Evgeny; Kozyura, Alexey; Moryakin, Sergey

    2013-04-01

    The spectrometer for the monitoring of Earth atmospheric ozone from the board of spacecraft is being designed. The aim of the spectrometer called "Ozonometer" is global and permanent monitoring of total ozone by means of measuring spectra of scattered solar radiation in near-UV and visible range of spectrum (300 - 500 nm). This range includes Huggins absorption band of ozone in near-UV (300 - 360 nm) and nitrogen dioxide NO2 absorption bands in visible light (400 - 500 nm). The optical design of the spectrometer is based on the Rowland circle scheme with holographic concave diffractive grating. An off-axis parabolic mirror is used as an entrance objective. The CCD detector is linear with 2048 pixels. The spectral resolution is up to 0.3 nm. The spectrometer is supposed to provide nadir observations but there is also an additional optical entrance orientated to Sun hemisphere in order to measure pure solar spectra. The spectrometer is being designed within Russian special federal program "Geophysics". Among the program, a group of 4 spacecrafts "Ionosphere" is to be launched in 2014-2015. They are planned to operate at a pair of circle solar-synchronous near-polar orbits (2 spacecrafts at each orbit). Up to the present moment, the qualification model of the spectrometer has been manufactured and tested. The first performance tests were completed at optical laboratories in St. Petersburg and Moscow with the help of Hg lamps and other light sources. After that, the field atmospheric measurements have been carried out in Moscow, Orel and at Kislovodsk high-altitude atmospheric station at Caucasus. The observations have been provided at zenith direction (scattered radiation) as well as solar direct measurements. The obtained results are presented.

  10. Structured Chirped Fiber Bragg Gratings

    Microsoft Academic Search

    Marco Pisco; Agostino Iadicicco; Stefania Campopiano; Antonello Cutolo; Andrea Cusano

    2008-01-01

    In this paper, a theoretical and numerical analysis of novel in-fiber photonic devices based on a structured chirped fiber Bragg gratings (CFBGs) for sensing and communication applications is presented. The investigated structure consists in a CFBG with single or multiple defects obtained by a deep and localized stripping of the cladding layer along the grating structure. The thinning of the

  11. Measurements on the Zeeman-splitting of analytical lines by means of a continuum source graphite furnace atomic absorption spectrometer with a linear charge coupled device array

    Microsoft Academic Search

    U. Heitmann; M. Schutz; H. Beckerrob; S. Florek

    1996-01-01

    A spectrometer for time-resolved high-resolution spectroscopic measurements of line splittings in inverse Zeeman effect corrected atomic absorption spectrometry is presented. The system consists of a continuum source, a longitudinal Zeeman-THGA module, a high-resolution double echelle monochromator, and a linear CCD array. Splitting patterns of atomic lines in a magnetic field have been determined and are compared with theory. The continuum

  12. Time- and frequency-domain models for Smith-Purcell radiation from a two-dimensional charge moving above a finite length grating

    SciTech Connect

    Kesar, Amit S.; Hess, Mark; Korbly, Stephen E.; Temkin, Richard J. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2005-01-01

    Smith-Purcell radiation (SPR), formed by an electron beam traveling above a grating, is a very promising source of coherent radiation from the THz to the optical regime. We present two theoretical calculations of the SPR from a two-dimensional bunch of relativistic electrons passing above a grating of finite length. The first calculation uses the finite-difference time-domain approach with the total-field/scattered-field procedure for fields incident on the grating. This calculation allows good physical insight into the radiation process and also allows arbitrary geometries to be treated. The second calculation uses an electric-field integral equation method. Good agreement is obtained between these two calculations. The results of these theoretical calculations are then compared with a theoretical formalism based on an infinite-length grating. The latter formalism allows periodic boundary conditions to be rigorously applied. For gratings with less than {approx}50 periods, a significant error in the strength of the radiated field is introduced by the infinite-grating approximation. It is shown that this error disappears asymptotically as the number of periods increases. The Wood-Rayleigh anomalies, predicted in the infinite-grating approximation, were not seen in our finite-grating calculations. The SPR resonance condition is the same in all three formalisms. Numerical examples are presented for an {approx}18 MeV, 50 nC/m, 200 {mu}m bunch traveling 0.6 mm above a ten-period echelle grating having a 2.1-mm periodicity.

  13. Synchrotron radiation calibration of the EUVE variable line-spaced diffraction gratings at the NBS SURF II facility

    NASA Technical Reports Server (NTRS)

    Jelinsky, P.; Jelinsky, S. R.; Miller, A.; Vallerga, J.; Malina, R. F.

    1988-01-01

    The Extreme Ultraviolet Explorer (EUVE) has a spectrometer which utilizes variable line-spaced, plane diffraction gratings in the converging beam of a Wolter-Schwarzschild type II mirror. The gratings, microchannel plate detector, and thin film filters have been calibrated with continuum radiation provided by the NBS SURF II facility. These were calibrated in a continuum beam to find edges or other sharp spectral features in the transmission of the filters, quantum efficiency of the microchannel plate detector, and efficiency of the gratings. The details of the calibration procedure and the results of the calibration are presented.

  14. A colloidal quantum dot spectrometer.

    PubMed

    Bao, Jie; Bawendi, Moungi G

    2015-07-01

    Spectroscopy is carried out in almost every field of science, whenever light interacts with matter. Although sophisticated instruments with impressive performance characteristics are available, much effort continues to be invested in the development of miniaturized, cheap and easy-to-use systems. Current microspectrometer designs mostly use interference filters and interferometric optics that limit their photon efficiency, resolution and spectral range. Here we show that many of these limitations can be overcome by replacing interferometric optics with a two-dimensional absorptive filter array composed of colloidal quantum dots. Instead of measuring different bands of a spectrum individually after introducing temporal or spatial separations with gratings or interference-based narrowband filters, a colloidal quantum dot spectrometer measures a light spectrum based on the wavelength multiplexing principle: multiple spectral bands are encoded and detected simultaneously with one filter and one detector, respectively, with the array format allowing the process to be efficiently repeated many times using different filters with different encoding so that sufficient information is obtained to enable computational reconstruction of the target spectrum. We illustrate the performance of such a quantum dot microspectrometer, made from 195 different types of quantum dots with absorption features that cover a spectral range of 300 nanometres, by measuring shifts in spectral peak positions as small as one nanometre. Given this performance, demonstrable avenues for further improvement, the ease with which quantum dots can be processed and integrated, and their numerous finely tuneable bandgaps that cover a broad spectral range, we expect that quantum dot microspectrometers will be useful in applications where minimizing size, weight, cost and complexity of the spectrometer are critical. PMID:26135449

  15. Monitoring of Laser Material Welding Process Using UV-Visible Spectrometer

    SciTech Connect

    Genc, B.; Kacar, E.; Akman, E.; Demir, A. [University of Kocaeli, Laser Technologies Research and Application Center, Kocaeli (Turkey)

    2007-04-23

    UV-Visible spectrometer is used to record emission from magnesium and titanium metal plates during laser welding processing. Geometrically corrected Czerny-Turner configurations nearly eliminate defocusing problem. The Optikwerks software is used to find the optimum Czerny-Turner configuration and to choose optical elements such as grating types, mirrors focal length and diameter, and slit width. The design parameters of the uv-visible spectrometer in the wavelength range 200-1100 nm for monitoring laser material welding processing.

  16. Auroral spectrometer AF6 for the POLAR HIGH ATMOSPHERE rocket campaign

    NASA Astrophysics Data System (ADS)

    Fischer, F.; Knothe, M.; Schmidtke, G.

    1981-02-01

    An extreme ultraviolet (EUV) spectrometer for the polar high atmosphere experiment and the results of two flights are presented. The optical concept is based on Rowland grating geometry using the blaze effect and providing a high efficiency spectrometer. Height, profiles of important spectral emissions such as O2 and O1 are obtained and strong differences in the spatial distribution of emissions with different optical depths are shown in the spectral region.

  17. A spectrometer for high-resolution and high-contrast Brillouin spectroscopy in the ultraviolet

    Microsoft Academic Search

    Paola Benassi; Roberto Eramo; Andrea Giugni; Michele Nardone; Marco Sampoli

    2005-01-01

    We present a multiple-grating spectrometer designed for high-resolution and high-contrast low-frequency scattering spectroscopy in the ultraviolet, as well as in the visible spectral regions. The instrument has a resolution better than 1 GHz and a contrast of about 1×10-10 both in the visible and in the UV range, thus doubling the highest resolution achieved by double-monochromator double-pass spectrometers such as

  18. Techniques for characterizing waveguide gratings and grating-based devices

    NASA Astrophysics Data System (ADS)

    Brinkmeyer, Ernst; Kieckbusch, Sven; Knappe, Frank

    2006-09-01

    Waveguide gratings used in laser technology, optical sensing or optical communications have to serve different specific purposes and, hence, have to have specific optical properties which can be tailored to a large extent. Characterization methods are required not only to measure the actual effect of a Bragg grating or long period grating under consideration but also to unveil the cause, i.e. to determine its spatial structure. This paper reviews the present status of the respective experimental characterization techniques. The methods emphasized rely on phase sensitive reflectometry together with advanced inverse scattering evaluation algorithms.

  19. FIES: The high-resolution Fiber-fed Echelle Spectrograph at the Nordic Optical Telescope

    NASA Astrophysics Data System (ADS)

    Telting, J. H.; Avila, G.; Buchhave, L.; Frandsen, S.; Gandolfi, D.; Lindberg, B.; Stempels, H. C.; Prins, S.; NOT staff

    2014-01-01

    FIES is a cross-dispersed high-resolution echelle spectrograph at the 2.56 m Nordic Optical Telescope (NOT), and was optimised for throughput and stability in 2006. The major 2006 upgrade involved the relocation of FIES to a stable environment and development of a fiber bundle that offers 3 different resolution modes, and made FIES an attractive tool for the user community of the NOT. Radial-velocity stability is achieved through double-chamber active temperature control. A dedicated data reduction tool, FIEStool, was developed. As a result of these upgrades, FIES is now one of the work-horse instruments at the NOT.

  20. Slow light based on holographic gratings

    Microsoft Academic Search

    Guoquan Zhang

    2011-01-01

    We have reviewed recent progresses on slow light based on holographic gratings such as stationary gratings, nonlinearly induced dynamic gratings and atomic coherence gratings. Several applications such as addressable multi-channel all-optical buffer memory and stored phase conjugate light wave based on slow light and stopped light pulses will be addressed. I. INTRODUCTION Slow light has been studied intensively in the

  1. Analysis of grating surface emitting lasers

    Microsoft Academic Search

    R. J. Noll; S. H. Macomber

    1990-01-01

    An approach to the analysis of grating-coupled semiconductor lasers is presented. It is shown that there are only two resonant solutions when the grating has infinite extent. The solutions are either symmetric or antisymmetric about the center of the longitudinal coordinate system where the antisymmetric solution is nonradiating. The field in the grating layer is expressed in terms of grating

  2. Fiber Bragg grating technology fundamentals and overview

    Microsoft Academic Search

    Kenneth O. Hill; Gerald Meltz

    1997-01-01

    The historical beginnings of photosensitivity and fiber Bragg grating (FBG) technology are recounted. The basic techniques for fiber grating fabrication, their characteristics, and the fundamental properties of fiber gratings are described. The many applications of fiber grating technology are tabulated, and some selected applications are briefly described

  3. Casimir Interaction of Dielectric Gratings

    SciTech Connect

    Lambrecht, Astrid [Laboratoire Kastler Brossel, CNRS, ENS, UPMC, Campus Jussieu case 74, 75252 Paris (France); Marachevsky, Valery N. [Laboratoire Kastler Brossel, CNRS, ENS, UPMC, Campus Jussieu case 74, 75252 Paris (France); V. A. Fock Institute of Physics, St. Petersburg State University, 198504 St. Petersburg (Russian Federation)

    2008-10-17

    We derive an exact solution for the Casimir force between two arbitrary periodic dielectric gratings and illustrate our method by applying it to two nanostructured silicon gratings. We also reproduce the Casimir force gradient measured recently [H. B. Chan, Y. Bao, J. Zou, R. A. Cirelli, F. Klemens, W. M. Mansfield, and C. S. Pai, Phys. Rev. Lett. 101, 030401 (2008)] between a silicon grating and a gold sphere taking into account the material dependence of the force. We find good agreement between our theoretical results and the measured values both in absolute force values and the ratios between the exact force and proximity force approximation predictions.

  4. Grating-structured metallic microsprings

    NASA Astrophysics Data System (ADS)

    Huang, Tao; LiuThe First Two Authors Contributed Equally To This Work., Zhaoqian; Huang, Gaoshan; Liu, Ran; Mei, Yongfeng

    2014-07-01

    We fabricate grating-structured metallic microsprings with well-defined helical angles and diameters, which are self-rolled from strained nanomembranes patterned with gratings. The grating structures on the metal membrane, replicated from the imprinted polymer layer beneath, give rise to the controlled rolling direction after selective etching of the underlying sacrificial layer. The rolling direction of the grating-structured thin metal film is always perpendicular to the long side edge of gratings, offering a good way to roll up strained strips into well controlled three-dimensional (3D) microsprings simply by altering the dimension and orientation of the structured strips. The mechanical elasticity of these grating-structured metallic microsprings is verified for the potential application as a flow rate sensor. Our work may stimulate rigorous synthesis of highly functional and complex 3D helical micro and nanostructures, and hint a broad range of applications such as environmental sensors, micro-/nanoscale robots, metamaterials, etc.We fabricate grating-structured metallic microsprings with well-defined helical angles and diameters, which are self-rolled from strained nanomembranes patterned with gratings. The grating structures on the metal membrane, replicated from the imprinted polymer layer beneath, give rise to the controlled rolling direction after selective etching of the underlying sacrificial layer. The rolling direction of the grating-structured thin metal film is always perpendicular to the long side edge of gratings, offering a good way to roll up strained strips into well controlled three-dimensional (3D) microsprings simply by altering the dimension and orientation of the structured strips. The mechanical elasticity of these grating-structured metallic microsprings is verified for the potential application as a flow rate sensor. Our work may stimulate rigorous synthesis of highly functional and complex 3D helical micro and nanostructures, and hint a broad range of applications such as environmental sensors, micro-/nanoscale robots, metamaterials, etc. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr00316k

  5. Deep Echelle Spectrophotometry of S 311, a galactic H II Region Outside the Solar Circle

    E-print Network

    J. Garcia-Rojas; C. Esteban; A. Peimbert; M. Peimbert; M. Rodriguez; M. T. Ruiz

    2005-06-17

    We present echelle spectrophotometry of the Galactic H II region S 311. The data have been taken with the Very Large Telescope UVES echelle spectrograph in the 3100 to 10400 angstroms range. We have measured the intensities of 263 emission lines, 178 are permitted lines of H0, D0 (deuterium), He0, C0, C+, N0, N+, O0, O+, S+, Si0, Si+, Ar0 and Fe0; some of them are produced by recombination and others mainly by fluorescence. Physical conditions have been derived using different continuum and line intensity ratios. We have derived He+, C++ and O++ ionic abundances from pure recombination lines as well as abundances from collisionally excited lines for a large number of ions of different elements. We have obtained consistent estimations of t2 applying different methods. We have found that the temperature fluctuations paradigm is consistent with the t2(He I) vs. t2(H I) relation for H II regions, in contrast with what has been found for planetary nebulae. We report the detection of deuterium Balmer lines up to D6 in the blue wings of the hydrogen lines, which excitation mechanism seems to be continuum fluorescence.

  6. Encapsulation process for diffraction gratings.

    PubMed

    Ratzsch, Stephan; Kley, Ernst-Bernhard; Tünnermann, Andreas; Szeghalmi, Adriana

    2015-07-13

    Encapsulation of grating structures facilitates an improvement of the optical functionality and/or adds mechanical stability to the fragile structure. Here, we introduce novel encapsulation process of nanoscale patterns based on atomic layer deposition and micro structuring. The overall size of the encapsulated structured surface area is only restricted by the size of the available microstructuring and coating devices; thus, overcoming inherent limitations of existing bonding processes concerning cleanliness, roughness, and curvature of the components. Finally, the process is demonstrated for a transmission grating. The encapsulated grating has 97.5% transmission efficiency in the -1st diffraction order for TM-polarized light, and is being limited by the experimental grating parameters as confirmed by rigorous coupled wave analysis. PMID:26191855

  7. Fiber Grating Environmental Sensing System

    DOEpatents

    Schulz, Whitten L. (Fairview, OR); Udd, Eric (Fairview, OR)

    2003-07-29

    Fiber grating environmental measurement systems are comprised of sensors that are configured to respond to changes in moisture or chemical content of the surrounding medium through the action of coatings and plates inducing strain that is measured. These sensors can also be used to monitor the interior of bonds for degradation due to aging, cracking, or chemical attack. Means to multiplex these sensors at high speed and with high sensitivity can be accomplished by using spectral filters placed to correspond to each fiber grating environmental sensor. By forming networks of spectral elements and using wavelength division multiplexing arrays of fiber grating sensors may be processed in a single fiber line allowing distributed high sensitivity, high bandwidth fiber optic grating environmental sensor systems to be realized.

  8. Sputtered-sliced multilayers: Zone plates and transmission gratings for 8-keV x rays

    SciTech Connect

    Bionta, R.M.; Ables, E.; Cook, K.J.; Edwards, O.D.; Gabriele, P.C.; Jankowski, A.F.; Makowiecki, D.M.; Ott, L.L.; Thomas, N.

    1988-07-29

    We have made and tested several sliced multilayer structures that can function as transmissive x-ray optical elements (diffraction gratings, zone plates and phase gratings) at 8-keV. Both amplitude-modulating and phase-modulating devices have been produced. We show data taken in the beam of a 8 keV x-ray source that demonstrate diffraction and focusing. The diffraction patterns produced by the multilayer devices closely match theoretical predictions. Such transmissive optics have the potential for a wide application to high-resolution microscope and spectrometer systems. 6 refs., 15 figs.

  9. MEMS Bragg grating force sensor.

    PubMed

    Reck, Kasper; Thomsen, Erik V; Hansen, Ole

    2011-09-26

    We present modeling, design, fabrication and characterization of a new type of all-optical frequency modulated MEMS force sensor based on a mechanically amplified double clamped waveguide beam structure with integrated Bragg grating. The sensor is ideally suited for force measurements in harsh environments and for remote and distributed sensing and has a measured sensitivity of -14 nm/N, which is several times higher than what is obtained in conventional fiber Bragg grating force sensors. PMID:21996861

  10. Integrated AWG spectrometer for on-chip optical coherence tomography and Raman spectroscopy

    Microsoft Academic Search

    B. I. Akca; N. Ismail; F. Sun; A. Driessen; K. Wörhoff; M. Pollnau; Ridder de R. M; V. D. Nguyen; J. Kalkman; Leeuwen van T. G

    2010-01-01

    Silicon oxynitride-based arrayed waveguide grating (AWG) spectrometers were designed for on-chip spectral-domain optical coherence tomography (OCT) systems and Raman spectroscopy of the skin. A novel geometrical layout for Raman spectroscopy was introduced to reduce loss. Measurements show that integrated optics has a good potential for miniaturizing current OCT systems

  11. High performance Czerny-Turner imaging spectrometer with aberrations corrected by tilted lenses

    NASA Astrophysics Data System (ADS)

    Zhong, Xing; Zhang, Yuan; Jin, Guang

    2015-03-01

    The design of the high performance imaging spectrometer using low-cost plane grating is researched in this paper. In order to correct the aberrations well, under the guidance of the vector aberration theory, the modification of Czerny-Turner system with inserted tilt lenses is proposed. The novel design of a short-wave infrared imaging spectrometer working at between wavelengths of 1-2.5 ?m is shown as an example, whose numerical aperture achieves 0.15 in image space. The aberrations are corrected well and the Modulation Transfer Function (MTF) performance is the same as the convex gratings systems. The smiles and keystones of the spectral image are acceptable. Advantages of the proposed design with a plane grating are obviously that the diffraction efficiency is high while the cost is very low.

  12. Characterization of an InGaAs/InP-based Echelle mirror multiplexer for widely-tunable mid-IR sources based on quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Orbe, L. J.; Carpintero, G.; Gilles, C.; Boulila, F.; Maisons, G.; Carras, M.

    2015-03-01

    We present the experimental characterization results of a 15-to-1 wavelength multiplexer for a Distributed Feedback Quantum Cascade Laser (DFB QCL) array operating in the 7-8.5 ?m (mid-long) infrared (IR) range. This design is customized for its use to combine the output from a DFB QCL array with a 0.1 ?m wavelength channel spacing for spectroscopy applications, and it is proposed in order to achieve a continuous tuning range overcoming the limited tunability of a single QCLs, required for multi-gas or complex molecule detection. This multiplexer is based on an Echelle diffraction mirror grating scheme, in which multiple output waveguides are deliberately implemented in the design to de-risk for wavelength deviations in the fabrication process. We optimized the location of the input and output guides in order to allow for monolithic integration of the DFB QCL arrays, which would provide for a number of advantages such as a higher stability, less complexity and lower cost over other technologies such as external cavities. We discuss the effects over the device performance of the design, such as the diffraction effects, input channel width overlapping/crosstalk and input channel profile, which are very important to address in order to avoid unaccounted transmission losses. Other parameters such as the profile of the input and output waveguides and fabrication limitations are also discussed as their effect on the device is observed. A series of characterization tests are presented in order to compare the simulation results to the experimental data, which suggests that these multiplexers are a suitable option compared to other IR multiplexer schemes in terms of size and power transmission.

  13. Alignment of the Grating Wheel Mechanism for a Ground-Based, Cryogenic, Near-Infrared Astronomy Instrument

    NASA Technical Reports Server (NTRS)

    Gutkowski, Sharon M.; Ohl, Raymond G.; Hylan, Jason E.; Hagopian, John G.; Kraft, Stephen E.; Mentzell, J. Eric; Connelly, Joseph A.; Schepis, Joseph P.; Sparr, Leroy M.; Greenhouse, Matthew A.

    2003-01-01

    We describe the population, optomechanical alignment, and alignment verification of near-infrared gratings on the grating wheel mechanism (GWM) for the Infrared Multi-Object Spectrometer (IRMOS). IRMOS is a cryogenic (80 K), principle investigator-class instrument for the 2.1 m and Mayall 3.8 m telescopes at Kitt Peak National Observatory, and a MEMS spectrometer concept demonstrator for the James Webb Space Telescope. The GWM consists of 13 planar diffraction gratings and one flat imaging mirror (58 x 57 mm), each mounted at a unique compound angle on a 32 cm diameter gear. The mechanism is predominantly made of Al 6061. The grating substrates are stress relieved for enhanced cryogenic performance. The optical surfaces are replicated from off-the-shelf masters. The imaging mirror is diamond turned. The GWM spans a projected diameter of approx. 48 cm when fully assembled, utilizes several flexure designs to accommodate potential thermal gradients, and is controlled using custom software with an off-the-shelf controller. Under ambient conditions, each grating is aligned in six degrees of freedom relative to a coordinate system that is referenced to an optical alignment cube mounted at the center of the gear. The local tip/tilt (Rx/Ry) orientation of a given grating is measured using the zero-order return from an autocollimating theodolite. The other degrees of freedom are measured using a two-axis cathetometer and rotary table. Each grating's mount includes a one-piece shim located between the optic and the gear. The shim is machined to fine align each grating. We verify ambient alignment by comparing grating difractive properties to model predictions.

  14. First results from a next-generation off-plane X-ray diffraction grating

    NASA Astrophysics Data System (ADS)

    McEntaffer, Randall; DeRoo, Casey; Schultz, Ted; Gantner, Brennan; Tutt, James; Holland, Andrew; O'Dell, Stephen; Gaskin, Jessica; Kolodziejczak, Jeffrey; Zhang, William W.; Chan, Kai-Wing; Biskach, Michael; McClelland, Ryan; Iazikov, Dmitri; Wang, Xinpeng; Koecher, Larry

    2013-08-01

    Future NASA X-ray spectroscopy missions will require high throughput, high resolving power grating spectrometers. Off-plane reflection gratings are capable of meeting the performance requirements needed to realize the scientific goals of these missions. We have identified a novel grating fabrication method that utilizes common lithographic and microfabrication techniques to produce the high fidelity groove profile necessary to achieve this performance. Application of this process has produced an initial pre-master that exhibits a radial (variable line spacing along the groove dimension), high density (> 6000 grooves/mm), laminar profile. This pre-master has been tested for diffraction efficiency at the BESSY II synchrotron light facility and diffracts up to 55 % of incident light into usable spectral orders. Furthermore, tests of spectral resolving power show that these gratings are capable of obtaining resolving powers well above 1300 ( ?/? ?) with limitations due to the test apparatus, not the gratings. Obtaining these results has provided confidence that this fabrication process is capable of producing off-plane reflection gratings for the next generation of X-ray observatories.

  15. Holographic Gratings for Optical Processing

    NASA Technical Reports Server (NTRS)

    Kukhtarev, Nickolai

    2002-01-01

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

  16. Ultrastrong fiber gratings and their applications

    NASA Astrophysics Data System (ADS)

    Starodubov, Dmitry S.; Grubsky, Victor; Feinberg, Jack

    1999-12-01

    Fiber Bragg gratings are used in a wide variety of devices including sensors, tunable filters, and signal controllers for Wavelength Division Multiplexing. Bragg gratings can be formed in an optical fiber by illuminating the fiber from the side with a pattern of ultraviolet light. Most gratings are made using 240-nm light. However, by using 330-nm light the grating can be written right through the standard polymer coating of the fiber, which preserves the fiber's mechanical strength. We discuss some of the mechanisms that degrade the strength of fiber gratings. We also discuss applications of mechanically strong fiber gratings, including very wide (> 50 nm) tunable filters.

  17. FLAMBAGE ET EFFET D'ECHELLE DANS LES STRUCTURES SANDWICH BUCKLING AND SCALE EFFECTS IN SANDWICH STRUCTURES

    E-print Network

    Boyer, Edmond

    FLAMBAGE ET EFFET D'ECHELLE DANS LES STRUCTURES SANDWICH BUCKLING AND SCALE EFFECTS IN SANDWICH for both global and local buckling. In a perfect framework, analytical critical loads are extracted eigenvalue can correspond to the occurrence of global and local buckling (wrinkling). Then local and global

  18. Fiber-optic magnetometer for prime focus of 6-m BTA telescope based on suspended echelle spectrograph

    Microsoft Academic Search

    G. A. Chountonov

    2010-01-01

    We have developed and manufactured a fiber-optic magnetometer for the prime focus of the 6-m BTA telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences based on a suspended echelle spectrograph. The magnetometer is designed to improve the spectrum stability and eliminate the effect of instrumental polarization of the diagonal mirror on the results of magnetic field

  19. ORFEUS-SPAS - The Berkeley EUV spectrometer

    NASA Technical Reports Server (NTRS)

    Bowyer, Stuart; Hurwitz, Mark

    1990-01-01

    The Berkeley EUV spectrometer of ORFEUS-SPAS, a joint project of NASA and the BMFT, incorporates a set of four novel spherically figured, varied line-space gratings used in a geometry that is similar to that of the classic Rowland mount to span an interval of 390 and 1200 A. Two spectral detector units containing curved microchannel plates and delay-line anodes encode the arriving photons in digital format for telemetry. An additional optic directs the image of the source in the entrance aperture onto a sealed FUV detector which is used to track the source as it drifts during an observation, enabling a postflight reconstruction of the spacecraft pointing vector. This in turn makes it possible to define with precision the wavelength of each recorded photon.

  20. A Laser Frequency Comb System for Absolute Calibration of the VTT Echelle Spectrograph

    NASA Astrophysics Data System (ADS)

    Doerr, H.-P.; Steinmetz, T.; Holzwarth, R.; Kentischer, T.; Schmidt, W.

    2012-10-01

    A wavelength calibration system based on a laser frequency comb (LFC) was developed in a co-operation between the Kiepenheuer-Institut für Sonnenphysik, Freiburg, Germany and the Max-Planck-Institut für Quantenoptik, Garching, Germany for permanent installation at the German Vacuum Tower Telescope (VTT) on Tenerife, Canary Islands. The system was installed successfully in October 2011. By simultaneously recording the spectra from the Sun and the LFC, for each exposure a calibration curve can be derived from the known frequencies of the comb modes that is suitable for absolute calibration at the meters per second level. We briefly summarize some topics in solar physics that benefit from absolute spectroscopy and point out the advantages of LFC compared to traditional calibration techniques. We also sketch the basic setup of the VTT calibration system and its integration with the existing echelle spectrograph.

  1. Development, characterization and application of compact spectrometers based on MEMS with in-plane capacitive drives

    NASA Astrophysics Data System (ADS)

    Kenda, A.; Kraft, M.; Tortschanoff, A.; Scherf, Werner; Sandner, T.; Schenk, Harald; Luettjohann, Stephan; Simon, A.

    2014-05-01

    With a trend towards the use of spectroscopic systems in various fields of science and industry, there is an increasing demand for compact spectrometers. For UV/VIS to the shortwave near-infrared spectral range, compact hand-held polychromator type devices are widely used and have replaced larger conventional instruments in many applications. Still, for longer wavelengths this type of compact spectrometers is lacking suitable and affordable detector arrays. In perennial development Carinthian Tech Research AG together with the Fraunhofer Institute for Photonic Microsystems endeavor to close this gap by developing spectrometer systems based on photonic MEMS. Here, we review on two different spectrometer developments, a scanning grating spectrometer working in the NIR and a FT-spectrometer accessing the mid-IR range up to 14 ?m. Both systems are using photonic MEMS devices actuated by in-plane comb drive structures. This principle allows for high mechanical amplitudes at low driving voltages but results in gratings respectively mirrors oscillating harmonically. Both systems feature special MEMS structures as well as aspects in terms of system integration which shall tease out the best possible overall performance on the basis of this technology. However, the advantages of MEMS as enabling technology for high scanning speed, miniaturization, energy efficiency, etc. are pointed out. Whereas the scanning grating spectrometer has already evolved to a product for the point of sale analysis of traditional Chinese medicine products, the purpose of the FT-spectrometer as presented is to demonstrate what is achievable in terms of performance. Current developments topics address MEMS packaging issues towards long term stability, further miniaturization and usability.

  2. The Very precise Echelle SpectroPolarimeter on the Araki telescope (VESPolA)

    NASA Astrophysics Data System (ADS)

    Arasaki, Takayuki; Ikeda, Yuji; Shinnaka, Yoshiharu; Itose, Chisato; Nakamichi, Akika; Kawakita, Hideyo

    2015-06-01

    We report on the construction of a high-resolution spectropolarimeter, the Very precise Echelle SpectroPolarimeter on the Araki telescope (VESPolA). The instrument operates in the visible spectral range, i.e., 400-850 nm, and is mounted on the 1.3 m Araki telescope at the Koyama Astronomical Observatory of Kyoto Sangyo University (Kyoto, Japan). It employs an echelle-type spectrograph and a non-ripple super-achromatic half-wave plate, resulting in high polarimetric accuracy of ?P < 0.1% for linear polarization with a spectral resolution of R = 8000 at the central wavelengths and a wide wavelength coverage of ?? = 150-250 nm in a single exposure. VESPolA is designed for 1-2 m telescopes that have a Cassegrain focus. This configuration provides a dozen polarization line profiles of various nuclear species from the target spectra simultaneously, and we can therefore obtain complementary information on both the geometry and the velocity field of the nebular emission lines from the circumstellar envelopes. We evaluated the performance of our system by observing a spectroscopic standard star and several polarization standard stars during 2012-2013. VESPolA achieved a spectral resolution 7750 < R < 8250, with a polarimetric accuracy of ?P < 0.1% for linear polarization and a limiting magnitude of mv = 7.8 mag with ?P < 0.1% and an integration time of 4 hr. We show preliminary results of variable stars P Cyg, ? Lyr, and VY CMa. We observed polarization profiles across the H? and He lines, as well as the TiO absorption bands, which indicate a complex spatial distribution and velocity field of the surrounding gaseous nebulae.

  3. Microbolometer imaging spectrometer.

    PubMed

    Johnson, William R; Hook, Simon J; Shoen, Steven M

    2012-03-01

    Newly developed, high-performance, long-wave- and mid-wave-IR Dyson spectrometers offer a compact, low-distortion, broadband, imaging spectrometer design. The design is further accentuated when coupled to microbolometer array technology. This novel coupling allows radiometric and spectral measurements of high-temperature targets. It also serves to be unique since it allows for the system to be aligned warm. This eliminates the need for cryogenic temperature cycling. Proof of concept results are shown for a spectrometer with a 7.5 to 12.0 ?m spectral range and approximately 20 nm per spectral band (~200 bands). Results presented in this Letter show performance for remote hot targets (>200 °C) using an engineering grade spectrometer and IR commercial lens assembly. PMID:22378399

  4. The SLIM spectrometer.

    PubMed

    Cantrell, Kevin M; Ingle, James D

    2003-01-01

    A new spectrometer, here denoted the SLIM (simple, low-power, inexpensive, microcontroller-based) spectrometer, was developed that exploits the small size and low cost of solid-state electronic devices. In this device, light-emitting diodes (LED), single-chip integrated circuit photodetectors, embedded microcontrollers, and batteries replace traditional optoelectronic components, computers, and power supplies. This approach results in complete customizable spectrometers that are considerably less expensive and smaller than traditional instrumentation. The performance of the SLIM spectrometer, configured with a flow cell, was evaluated and compared to that of a commercial spectrophotometer. Thionine was the analyte, and the detection limit was approximately 0.2 microM with a 1.5-mm-path length flow cell. Nonlinearity due to the broad emission profile of the LED light sources is discussed. PMID:12530815

  5. Superheterodyne ESR-spectrometer

    Microsoft Academic Search

    I. A. Karpovich; L. V. Cvirko; V. B. Odzhaev; V. N. Popok; I. I. Azarko; A. D. Tarasevitch; V. P. Tolstykh

    1999-01-01

    A superheterodyne ESR spectrometer for automatic measurements has been designed. Superheterodyne realisation of the super-high-frequency section, computer control and data processing allow one to study signals of absorption and dispersion without frequency modulation

  6. The HERMES Spectrometer

    Microsoft Academic Search

    K. Ackerstaff; A. Airapetian; N. Akopov; M. Amarian; V. Andreev; E. C. Aschenauer; R. Avakian; H. Avakian; A. Avetissian; B. Bains; S. Barrow; W. Beckhusen; M. Beckmann; E. Belz; Th. Benisch; S. Bernreuther; N. Bianchi; J. Blouw; H. Böttcher; A. Borissov; J. Brack; B. Braun; B. Bray; S. Brons; W. Brückner; A. Brüll; H. J. Bulten; G. P. Capitani; P. Carter; P. Chumney; E. Cisbani; S. Clark; S. Colilli; H. Coombes; G. R. Court; P. Delheij; E. Devitsin; C. W. de Jager; E. De Sanctis; D. De Schepper; P. Di Nezza; M. Doets; M. Düren; A. Dvoredsky; G. Elbakian; J. Emerson; A. Fantoni; A. Fechtchenko; M. Ferstl; D. Fick; K. Fiedler; B. W. Filippone; H. Fischer; H. T. Fortune; J. Franz; S. Frullani; M.-A. Funk; N. D. Gagunashvili; P. Galumian; H. Gao; Y. Gärber; F. Garibaldi; G. Gavrilov; P. Geiger; V. Gharibyan; V. Giordjian; F. Giuliani; A. Golendoukhin; B. Grabowski; G. Graw; O. Grebeniouk; P. Green; G. Greeniaus; M. Gricia; C. Grosshauser; A. Gute; J. P. Haas; K. Hakelberg; W. Haeberli; J.-O. Hansen; D. Hasch; O. Hausser; R. Henderson; Th. Henkes; R. Hertenberger; Y. Holler; R. J. Holt; H. Ihssen; A. Izotov; M. Iodice; H. E. Jackson; A. Jgoun; C. Jones; R. Kaiser; J. Kelsey; E. Kinney; M. Kirsch; A. Kisselev; P. Kitching; H. Kobayashi; E. Kok; K. Königsmann; M. Kolstein; H. Kolster; W. Korsch; S. Kozlov; V. Kozlov; R. Kowalczyk; L. Kramer; B. Krause; A. Krivchitch; V. G. Krivokhijine; M. Kueckes; P. Kutt; G. Kyle; W. Lachnit; R. Langstaff; W. Lorenzon; M. Lucentini; A. Lung; N. Makins; V. Maleev; S. I. Manaenkov; K. Martens; A. Mateos; K. McIlhany; R. D. McKeown; F. Meißner; F. Menden; D. Mercer; A. Metz; N. Meyners; O. Mikloukho; C. A. Miller; M. A. Miller; R. Milner; V. Mitsyn; G. Modrak; J. Morton; A. Most; R. Mozzetti; V. Muccifora; A. Nagaitsev; Y. Naryshkin; A. M. Nathan; F. Neunreither; M. Niczyporuk; W.-D. Nowak; M. Nupieri; P. Oelwein; H. Ogami; T. G. O’Neill; R. Openshaw; V. Papavassiliou; S. F. Pate; S. Patrichev; M. Pitt; H. J. Plett; H. R. Poolman; S. Potashov; D. Potterveld; B. Povh; V. Prahl; G. Rakness; V. Razmyslovich; R. Redwine; A. R. Reolon; R. Ristinen; K. Rith; H. O. Roloff; G. Röper; P. Rossi; S. Rudnitsky; H. Russo; D. Ryckbosch; Y. Sakemi; F. Santavenere; I. Savin; F. Schmidt; H. Schmitt; G. Schnell; K. P. Schüler; A. Schwind; T.-A. Shibata; T. Shin; B. Siebels; A. Simon; K. Sinram; W. R. Smythe; J. Sowinski; M. Spengos; K. Sperber; E. Steffens; J. Stenger; J. Stewart; F. Stock; U. Stößlein; M. Sutter; H. Tallini; S. Taroian; A. Terkulov; D. Thiessen; B. Tipton; V. Trofimov; A. Trudel; M. Tytgat; G. M. Urciuoli; R. Van de Vyver; G. van der Steenhoven; J. J. van Hunen; D. van Westrum; A. Vassiliev; M. C. Vetterli; M. G. Vincter; E. Volk; W. Wander; T. P. Welch; S. E. Williamson; T. Wise; G. Wöbke; K. Woller; S. Yoneyama; K. Zapfe-Düren; T. Zeuli; H. Zohrabian

    1998-01-01

    The HERMES experiment is collecting data on inclusive and semi-inclusive deep inelastic scattering of polarised positrons from polarised targets of H, D, and 3He. These data give information on the spin structure of the nucleon. This paper describes the forward angle spectrometer built for this purpose. The spectrometer includes numerous tracking chambers (micro-strip gas chambers, drift and proportional chambers) in

  7. Characteristics of grating-assisted couplers.

    PubMed

    Izhaky, N; Hardy, A

    1999-12-01

    Characteristics of grating-assisted coupling between two parallel waveguides are analyzed. The influence of the grating parameters, such as groove depth, duty cycle, and refractive indices is considered. Chirped and parallel gratings as well as gratings with sinusoidal envelope periodicity are also addressed. The analysis is based on a unified coupled-mode formalism, with the transfer-matrix method as a general solution technique. It is shown how to modify the grating parameters to provide a specific spectral response (reflectivity and transmission coefficients). As an example, two parallel gratings are used to obtain a similar response to a single grating of double length. The location of the grating between the two waveguides as well as the light-wave injection direction are very important. The presented methods and effects may be useful for design and analysis in the fields of optical communications, sensing, and processing. PMID:18324242

  8. A new beam steering concept: Risley gratings

    NASA Astrophysics Data System (ADS)

    Oh, Chulwoo; Kim, Jihwan; Muth, John F.; Escuti, Michael J.

    2009-08-01

    We introduce a new beam steering concept of the "Risley grating" that consists of independently rotating inline polarization gratings (PGs). The Risley grating concept replaces the bulky prismatic elements of the Risley prisms with thin plates containing polarization gratings, and employs their highly polarization-sensitive diffraction. As rotating two PGs, the output beam tracks within a field-of-regard (FOR), which is determined by the grating period and their relative orientations. Since PGs are typically patterned in thin liquid crystal layers (a few ?m thick), the system can be implemented with far less thickness and weight. In addition, these thin gratings can be placed with virtually zero proximity and the beam walk-off becomes negligible. We demonstrate the Risley grating that performs continuous steering with 62° FOR and 89-92% transmittance at 1550 nm wavelength. The governing equations for the steering angles of the Risley grating in the direction cosine space are also presented.

  9. Fiber Bragg grating strain sensor demodulator using a chirped fiber grating

    Microsoft Academic Search

    Sungchul Kim; Seungwoo Kim; Jaejoon Kwon; Byoungho Lee

    2001-01-01

    A fiber Bragg grating (FBG) sensor demodulator using a chirped fiber grating is proposed. The demodulator uses UV-induced birefringence of chirped fiber grating to interrogate the wavelength shift of a sensor FBG. The demodulator is composed of a polarizing beam splitter, a polarization controller, a single-mode fiber, and a chirped fiber grating. The proposed demodulator is immune to light power

  10. Limitations of holographic grating lenses

    NASA Astrophysics Data System (ADS)

    Yao, S. K.

    1981-01-01

    The design aspects and the main parameters of periodic gratings in planar optical waveguides manufactured by holographic techniques are discussed. In particular, it is shown that there is a limitation on the size of the grating K-vector and the Bragg angle tolerance if low device insertion loss is desired. Typical index differences between the waveguide mode and the substrate mode is about 0.005 for a TI diffused LiNbO3 crystal and is less than 0.3 for sputtered thin-film waveguides on silicon or glass substrates. Thus, the maximum Bragg angle is approximately eight degrees for LiNbO3 and less than 45 degrees for glass or silicon substrates. The reflection angle for the optical beam is twice the Bragg angle. In order to achieve a large field of view, the grating periodicity should be optimized for each substrate parameter.

  11. Phase and absorption gratings for electrons

    NASA Astrophysics Data System (ADS)

    Gao, Hong; Gronniger, Glen; Freimund, Daniel; Cronin, Alex; Batelaan, Herman

    2003-04-01

    We report the experimental realization of phase and absorption gratings for electrons. Phase gratings made with standing waves of light with a periodicity of 266 nm are used to diffract 380 eV electrons [1]. Material gratings of 100 and 200 nm periodicity are used to diffract 500 eV electrons. We are exploring the possibility to use these gratings for low energy electron interferometry.

  12. Fiber coupled waveguide grating structures

    NASA Astrophysics Data System (ADS)

    Feng, Shengfei; Zhang, Xinping; Wang, Hao; Xin, Mudi; Lu, Zhenzhen

    2010-03-01

    Fabrication and characterization of the miniature device of waveguide grating-structures (WGS) on the end facet of an optical fiber are demonstrated. A layer of ZnO between the fiber and the grating structures serves as the waveguide. The fiber is used to direct the excitation light to the WGS and to carry the signal response back to the detection system. The narrow-band waveguide resonance mode tunable in the visible spectrum can be measured through the fiber in both the transmission and reflection. This nanodevice may be suitable as long-range sensors for the detection of refractive-index changes in nontransparent or toxic liquids.

  13. Development of microelectromechanical variable blaze gratings

    Microsoft Academic Search

    David M. Burns; Victor M. Bright

    1998-01-01

    Two types of microelectromechanical variable blaze gratings (VBGs) have been designed, modeled, fabricated, and tested. The gratings operate by adjusting the blaze angle of each slat so specular reflection of the incident light matches a particular grating diffraction order. The VBG blaze angle is adjustable with either electrostatic or thermal actuators. VBGs direct incident light in discrete directions, and are

  14. Strain sensors based on fiber Bragg gratings

    Microsoft Academic Search

    Piotr A. Kisaka; Elzbieta M. Beres-Pawlik; Jan Wojcik; Waldemar Wojcik

    2004-01-01

    In this paper, a review is given on the principles of optical fiber Bragg grating (FBG) sensors and their applications a strain sensors. Since the discovery of photosensitivity in optical fibers there has been great interest in the fabrication of Fiber Bragg Gratings within the core of a fiber. The ability to inscribe Bragg gratings in these photosensitive fibers has

  15. Embedded high-contrast distributed grating structures

    DOEpatents

    Zubrzycki, Walter J. (Albuquerque, NM); Vawter, Gregory A. (Albuquerque, NM); Allerman, Andrew A. (Albuquerque, NM)

    2002-01-01

    A new class of fabrication methods for embedded distributed grating structures is claimed, together with optical devices which include such structures. These new methods are the only known approach to making defect-free high-dielectric contrast grating structures, which are smaller and more efficient than are conventional grating structures.

  16. Diffraction gratings used as identifying markers

    DOEpatents

    Deason, Vance A. (Idaho Falls, ID); Ward, Michael B. (Idaho Falls, ID)

    1991-01-01

    A finely detailed defraction grating is applied to an object as an identifier or tag which is unambiguous, difficult to duplicate, or remove and transfer to another item, and can be read and compared with prior readings with relative ease. The exact pattern of the defraction grating is mapped by diffraction moire techniques and recorded for comparison with future readings of the same grating.

  17. One-dimensional space resolving flat-field holographic grating soft x-ray framing camera spectrograph for laser plasma diagnostics

    NASA Astrophysics Data System (ADS)

    Xiong, Gang; Hu, Zhimin; Li, Hang; Zhao, Yang; Shang, Wanli; Zhu, Tuo; Wei, Minxi; Yang, Guohong; Zhang, Jiyan; Yang, Jiamin

    2011-04-01

    A 1D space resolving x-ray spectrum diagnostic system has been developed to study the radiation opacity of hot plasma on SG-II laser facility. The diagnostic system consists of a 2400 lines/mm flat-field holographic grating and a gated microchannel plate coupled with an optical CCD and covers the wavelength range of 5-50 Å. The holographic grating was compared with a ruled one by measuring the emission spectra from a laser-produced molybdenum plasma. The results indicate that the holographic grating possesses better sensitivity than the ruled grating having nearly similar spectral resolution. The spectrograph has been used in radiative opacity measurement of Fe plasma. Simultaneous measurements of the backlight source and the transmission spectrum in appointed time range in one shot have been accomplished successfully with the holographic grating spectrometer. The 2p-3d transition absorption of Fe plasma near 15.5Å in has been observed clearly.

  18. Calibration of VUV spectrometer-detector system using synchrotron radiation

    SciTech Connect

    McPherson, A.; Rouze, N.; Westerveld, W.B.; Risley, J.S.

    1986-01-15

    A new technique and apparatus have been developed for the measurement of absolute electron impact photoemission cross sections in the 30--150-nm wavelength range. Synchrotron light is used as the primary intensity standard for the calibration of the detection efficiency of a vacuum ultraviolet (VUV) spectrometer-detector system. A multiadjustable manipulator was used to position precisely a Seya-Namioka-type spectrometer-detector system with respect to a narrow ray of synchrotron radiation. By scanning the beam of synchrotron radiation across the surface of the grating in the spectrometer, precise simulation of the geometry of the light source encountered in the electron impact photoemission mesurement was realized. Analysis of the results underscores the fact that for spectrometer calibrations in the VUV, the calibration procedure depends on the geometry of the experimental source. The simultaneous determination of the absolute apparatus response function of the spectrometer--detector system and the geometrical factors pertaining to the electron impact photoemission source allows photoemission cross sections in the VUV to be determined with unparalleled precision.

  19. Hadamard spectrometer for passive LWIR standoff surveillance

    NASA Astrophysics Data System (ADS)

    Kruzelecky, Roman V.; Wong, Brian; Zou, Jing; Mohammad, Najeeb; Jamroz, Wes; Soltani, Mohammed; Chaker, Mohamed; Haddad, Emile; Laou, Philips; Paradis, Suzanne

    2007-06-01

    Based on the principle of the Integrated Optical Spectrometer (IOSPEC), a waveguide-based, longwave infrared (LWIR) dispersive spectrometer with multiple input slits for Hadamard spectroscopy was designed and built intended for passive standoff chemical agent detection in 8 to 12?m spectral range. This prototype unit equips with a three-inch input telescope providing a field-of-view of 1.2 degrees, a 16-microslit array (each slit 60 ?m by 1.8 mm) module for Hadamard binary coding, a 2-mm core ZnS/ZnSe/ZnS slab waveguide with a 2 by 2 mm2 optical input and micro-machined integrated optical output condensor, a Si micro-machined blazing grating, a customized 128-pixel LWIR mercury-cadmium-telluride (MCT) LN2 cooled detector array, proprietary signal processing technique, software and electronics. According to the current configuration, it was estimated that the total system weight to be ~4 kg, spectral resolution <4cm -1 and Noise Equivalent Spectral Radiance (NESR) <10 -8 Wcm -2 sr -1cm -1 in 8 to 12 ?m. System design and preliminary test results of some components will be presented. Upon the arrival of the MCT detector array, the prototype unit will be further tested and its performance validated in fall of 2007.

  20. Nonparallel Light, Plane Grating Monochromator

    Microsoft Academic Search

    Murphy L. Dalton

    1962-01-01

    A high speed plane grating monochromatic illuminator intended for the vacuum ultraviolet and using nonparallel light is described. The light undergoes only two reflections between entrance slit and exit slit. Entrance slit and exit slit are on the principal axis of an ellipsoidal mirror, thereby eliminating astigmatism and spherical aberration.

  1. Subwavelength Metal Grating Tunable Filter

    Microsoft Academic Search

    J. Provine; Jack Skinner; David A. Horsley

    2006-01-01

    This paper reports on the integration of subwavelength metal gratings with surface micro-machined, electrostatic MEMS actuators to produce a tunable electromagnetic filter. Metal films perforated with periodically-spaced subwavelength diameter holes have been shown to transmit light with greater efficiency than predicted by classical models for evanescent propagation. Additionally, the field propagation shows strong dependance on the index of refraction on

  2. Calculation of thermal noise in grating reflectors

    E-print Network

    Daniel Heinert; Stefanie Kroker; Daniel Friedrich; Stefan Hild; Ernst-Bernhard Kley; Sean Leavey; Iain W. Martin; Ronny Nawrodt; Andreas Tünnermann; Sergey P. Vyatchanin; Kazuhiro Yamamoto

    2013-08-30

    Grating reflectors have been repeatedly discussed to improve the noise performance of metrological applications due to the reduction or absence of any coating material. So far, however, no quantitative estimate on the thermal noise of these reflective structures exists. In this work we present a theoretical calculation of a grating reflector's noise. We further apply it to a proposed 3rd generation gravitational wave detector. Depending on the grating geometry, the grating material and the temperature we obtain a thermal noise decrease by up to a factor of ten compared to conventional dielectric mirrors. Thus the use of grating reflectors can substantially improve the noise performance in metrological applications.

  3. Electromagnetically induced grating with maximal atomic coherence

    SciTech Connect

    Carvalho, Silvania A.; Araujo, Luis E. E. de [Instituto de Fisica ''Gleb Wataghin'', Universidade Estadual de Campinas, Campinas-SP, 13083-859 Sao Paulo (Brazil)

    2011-10-15

    We describe theoretically an atomic diffraction grating that combines an electromagnetically induced grating with a coherence grating in a double-{Lambda} atomic system. With the atom in a condition of maximal coherence between its lower levels, the combined gratings simultaneously diffract both the incident probe beam as well as the signal beam generated through four-wave mixing. A special feature of the atomic grating is that it will diffract any beam resonantly tuned to any excited state of the atom accessible by a dipole transition from its ground state.

  4. Electron-proton spectrometer

    NASA Technical Reports Server (NTRS)

    Winckler, J. R.

    1973-01-01

    An electron-proton spectrometer was designed to measure the geomagnetically trapped radiation in a geostationary orbit at 6.6 earth radii in the outer radiation belt. This instrument is to be flown on the Applications Technology Satellite-F (ATS-F). The electron-proton spectrometer consists of two permanent magnet surface barrier detector arrays and associated electronics capable of selecting and detecting electrons in three energy ranges: (1) 30-50 keV, (2) 150-200 keV, and (3) 500 keV and protons in three energy ranges. The electron-proton spectrometer has the capability of measuring the fluxes of electrons and protons in various directions with respect to the magnetic field lines running through the satellite. One magnet detector array system is implemented to scan between EME north and south through west, sampling the directional flux in 15 steps. The other magnet-detector array system is fixed looking toward EME east.

  5. Demonstration of Silicon-on-insulator mid-infrared spectrometers operating at 3.8 ?m.

    PubMed

    Muneeb, M; Chen, X; Verheyen, P; Lepage, G; Pathak, S; Ryckeboer, E; Malik, A; Kuyken, B; Nedeljkovic, M; Van Campenhout, J; Mashanovich, G Z; Roelkens, G

    2013-05-20

    The design and characterization of silicon-on-insulator mid-infrared spectrometers operating at 3.8 ?m is reported. The devices are fabricated on 200 mm SOI wafers in a CMOS pilot line. Both arrayed waveguide grating structures and planar concave grating structures were designed and tested. Low insertion loss (1.5-2.5 dB) and good crosstalk characteristics (15-20 dB) are demonstrated, together with waveguide propagation losses in the range of 3 to 6 dB/cm. PMID:23736389

  6. Single-lens computed tomography imaging spectrometer and method of capturing spatial and spectral information

    NASA Technical Reports Server (NTRS)

    Wilson, Daniel W. (Inventor); Johnson, William R. (Inventor); Bearman, Gregory H. (Inventor)

    2011-01-01

    Computed tomography imaging spectrometers ("CTISs") employing a single lens are provided. The CTISs may be either transmissive or reflective, and the single lens is either configured to transmit and receive uncollimated light (in transmissive systems), or is configured to reflect and receive uncollimated light (in reflective systems). An exemplary transmissive CTIS includes a focal plane array detector, a single lens configured to transmit and receive uncollimated light, a two-dimensional grating, and a field stop aperture. An exemplary reflective CTIS includes a focal plane array detector, a single mirror configured to reflect and receive uncollimated light, a two-dimensional grating, and a field stop aperture.

  7. SPRED: a multichannel grazing-incidence spectrometer for plasma impurity diagnosis

    SciTech Connect

    Fonck, R.J.; Ramsey, A.T.; Yelle, R.V.

    1982-03-01

    A compact vacuum ultraviolet spectrometer system has been developed to provide time-resolved impurity spectra from tokamak plasmas. Two interchangeable aberration-corrected toroidal diffraction gratings with flat focal fields provide simultaneous coverage over the ranges 100 to 1100 A or 160 to 1700 A. The detector is an intensified self-scanning photodiode array. Spectral resolution is 2 A with the higher dispersion grating. Minimum readout time for a full spectrum is 20 ms, but up to 7 individual spectral lines can be measured with a 1 ms time resolution. The sensitivity of the system is comparable to that of a conventional grazing incidence monochromator.

  8. The Apollo Alpha Spectrometer.

    NASA Technical Reports Server (NTRS)

    Jagoda, N.; Kubierschky, K.; Frank, R.; Carroll, J.

    1973-01-01

    Located in the Science Instrument Module of Apollo 15 and 16, the Alpha Particle Spectrometer was designed to detect and measure the energy of alpha particles emitted by the radon isotopes and their daughter products. The spectrometer sensor consisted of an array of totally depleted silicon surface barrier detectors. Biased amplifier and linear gate techniques were utilized to reduce resolution degradation, thereby permitting the use of a single 512 channel PHA. Sensor identification and in-flight radioactive calibration were incorporated to enhance data reduction.

  9. Fiber-optic magnetometer for prime focus of 6-m BTA telescope based on suspended echelle spectrograph

    Microsoft Academic Search

    G. A. Chountonov

    2010-01-01

    We have developed and manufactured a fiber-optic magnetometer for the prime focus of the 6-m BTA telescope of the Special\\u000a Astrophysical Observatory of the Russian Academy of Sciences based on a suspended echelle spectrograph. The magnetometer is\\u000a designed to improve the spectrum stability and eliminate the effect of instrumental polarization of the diagonal mirror on\\u000a the results of magnetic field

  10. Library of flux-calibrated echelle spectra of southern late-type dwarfs with different activity levels

    Microsoft Academic Search

    C. Cincunegui; P. J. D. Mauas

    2004-01-01

    We present Echelle spectra of 91 late-type dwarfs, of spectral types from F to M and of different levels of chromospheric activity, obtained with the 2.15 m telescope of the CASLEO Observatory located in the Argentinean Andes. Our observations range from 3890 to 6690 Å, at a spectral resolution from 0.141 to 0.249 Å per pixel (R=lambda\\/delta lambda ≈ 26

  11. Hyperspectral data collections with the new wedge imaging spectrometer

    SciTech Connect

    Jeter, J.W.; Hartshorne, R.; Thunen, J.G. [Hughes Santa Barbara Remote Sensing (SBRS), Goleta, CA (United States)

    1996-11-01

    The Wedge Imaging Spectrometer (WIS) applies a unique technology to hyperspectral imaging systems, allowing flexibility and high performance in a very compact package. This innovation is based on the use of a linear spectral wedge filter mated directly to an area detector array, avoiding the use of bulky and complex optics required for imaging spectrometers based on gratings or prism concepts. The technology was realized in an earlier flight demonstration system as previously reported. Second generation VNIR and SWIR instruments have now been developed, each with two filters whose spectral bandwidths are optimized for specific spectral features. The SWIR instrument can be extended to operate in the 3-5 PM mid-wave spectral region. The new instrument is currently completing its integration and test phase. Preliminary results indicate excellent performance potential for a wide range of applications. 2 figs., 1 tab.

  12. Galileo Probe Mass Spectrometer

    NASA Technical Reports Server (NTRS)

    Owen, Tobias C.

    1998-01-01

    During the past year, the Principal Investigator's research carried out under this contract has focused on an analysis of the implications of Galileo Probe Mass Spectrometer (GPMS) results for the origin of Jupiter's atmosphere and the origin of the ice and other possible volatiles on the Galilean satellites.

  13. Mass spectrometer mixture calibrations

    Microsoft Academic Search

    Hicks

    1986-01-01

    Mass spectrometric analyses of hydrogen isotope mixtures can be difficult to make for a number of reasons. The most difficult problem is the possibility of confronting extremely great and extremely small relative mass differences in the same analysis. Commercial mass spectrometers are now available that can overcome these problems. The analytical capabilities and limitations of these instruments will be discussed.

  14. Mass Spectrometers in Space!

    NASA Technical Reports Server (NTRS)

    Brinckerhoff, William B.

    2012-01-01

    Exploration of our solar system over several decades has benefitted greatly from the sensitive chemical analyses offered by spaceflight mass spectrometers. When dealing with an unknown environment, the broadband detection capabilities of mass analyzers have proven extremely valuable in determining the composition and thereby the basic nature of space environments, including the outer reaches of Earth s atmosphere, interplanetary space, the Moon, and the planets and their satellites. Numerous mass analyzer types, including quadrupole, monopole, sector, ion trap, and time-of-flight have been incorporated in flight instruments and delivered robotically to a variety of planetary environments. All such instruments went through a rigorous process of application-specific development, often including significant miniaturization, testing, and qualification for the space environment. Upcoming missions to Mars and opportunities for missions to Venus, Europa, Saturn, Titan, asteroids, and comets provide new challenges for flight mass spectrometers that push to state of the art in fundamental analytical technique. The Sample Analysis at Mars (SAM) investigation on the recently-launch Mars Science Laboratory (MSL) rover mission incorporates a quadrupole analyzer to support direct evolved gas as well as gas chromatograph-based analysis of martian rocks and atmosphere, seeking signs of a past or present habitable environment. A next-generation linear ion trap mass spectrometer, using both electron impact and laser ionization, is being incorporated into the Mars Organic Molecule Analyzer (MOMA) instrument, which will be flown to Mars in 2018. These and other mass spectrometers and mission concepts at various stages of development will be described.

  15. ablation laser spectrometer

    E-print Network

    ablation laser mass spectrometer molecular beam REMPI laser NREL has designed and developed a combined laser ablation/ pulsed sample introduction/mass spectrometry platform that integrates pyrolysis and/or laser ablation with resonance- enhanced multiphoton ionization (REMPI) time-of-flight mass

  16. ORFEUS II echelle spectra: Absorption by H_2 in the LMC

    NASA Astrophysics Data System (ADS)

    de Boer, K. S.; Richter, P.; Bomans, D. J.; Heithausen, A.; Koornneef, J.

    We present the first detection of H_2 UV absorption profiles on the line of sight to the LMC. The star LH 10:3120 in the LMC was measured with the ORFEUS telescope and the Tue/HD echelle spectrograph during the space shuttle mission of Nov./Dec. 1996. 16 absorption lines from the Lyman band are used to derive the column densities of H_2 for the lowest 5 rotational states in the LMC gas. For these states we find a total column density of N(H_2)total=6.6 x 1018 cm^{-2} on this individual line of sight. We obtain equivalent excitation temperatures of Tex <= 50 K for the rotational ground state and Tex ~= 470 K for 1 <= J <= 5 by fitting the population densities of the rotational states to theoretical Boltzmann distributions. We conclude that UV pumping dominates the population of the higher rotational levels, as known from the H_2 gas in the Milky Way. (Research supported in part by the DARA)

  17. Measuring the temporal coherence of a high harmonic generation setup employing a Fourier transform spectrometer for the VUV/XUV

    NASA Astrophysics Data System (ADS)

    Terschlüsen, J. A.; Agåker, M.; Svanqvist, M.; Plogmaker, S.; Nordgren, J.; Rubensson, J.-E.; Siegbahn, H.; Söderström, J.

    2014-12-01

    In this experiment we used an 800 nm laser to generate high-order harmonics in a gas cell filled with Argon. Of those photons, a harmonic with 42 eV was selected by using a time-preserving grating monochromator. Employing a modified Mach-Zehnder type Fourier transform spectrometer for the VUV/XUV it was possible to measure the temporal coherence of the selected photons to about 6 fs. We demonstrated that not only could this kind of measurement be performed with a Fourier transform spectrometer, but also with some spatial resolution without modifying the XUV source or the spectrometer.

  18. Double-grating-structured light microscopy using plasmonic nanoparticle arrays

    E-print Network

    Exeter, University of

    with position the grating can be moved by changing the input polarization. A projected optical grating provides of the projected grating. Heinzmann et al. [3] have pro- posed nonlinear SIM involving saturation of fluoro- phores grating in a fluores- cent microscope. The physical grating used here relies on the local- ized surface

  19. [Design of the airborne prism dispersive imaging spectrometer system based on Offner relay configuration].

    PubMed

    Fang, Yu; Xiangli, Bin; Yuan, Yan; Lü, Qun-Bo; Zhou, Jin-Song

    2013-03-01

    Considering the development of the need for small volume and light weight of spectral imaging systems on airborne platform, the characters of several main imaging spectrometers was analyzed and the present paper focuses on introducing imaging spectrometers featuring a grating or a prism disperser. A compact hyperspectral imaging system based on Offner relay configuration is reported. Combining the characters of the concentric Offner relay, and knowing the system design parameters, two novel kinds of spherical spectrometer systems using dispersive elements in divergent and convergent beam were designed. Moreover, the system MTF, spot diagram and the curves of smile and keystone were analyzed. The results show that these two kinds of Offner spectrometer achieve the purpose of a compact form of remote sensing system with excellent imaging quality close to diffraction limit. At the same time, decreasing the smile and keystone to a small (0.1) fraction of a pixel assures uniformity of acquiring spectral data. PMID:23705466

  20. Reversible Shape Memory Optical Gratings

    NASA Astrophysics Data System (ADS)

    Li, Qiaoxi; Tippets, Cary; Fu, Yulan; Donev, Eugene; Turner, Sara; Ashby, Valerie; Lopez, Rene; Sheiko, Sergei

    2015-03-01

    Recent advancements in the understanding of the mechanisms that control shape memory in semi-crystalline polymers, has led to the development of protocols that allow for reversibility in complex shape transformations. The shifting between two programmable shapes is reversible without applying any external force. This is made possible by thermodynamically driven relaxation of extended polymer chains on heating is then inverted by kinetically preferred pathways of polymer crystallization on cooling. Reversible shapeshifting was applied to modulation of photonic gratings to create hands-free reversibly tunable optical elements. We have fabricated a sub-micron ratio optical square grating that presents reversible magnitude changes of its diffraction intensity (up to about 38% modulation) when subject to changes in temperature. This result is attributed to programmable changes in the grating height due to reversible shape memory and is repeatable over multiple cycles. Besides, roughness-induced variations in scattering signal observed upon heating-cooling cycles may offer another way to monitor kinetics of polymer melting and crystallization. Grants: NSF DMR-1407645,

  1. Simulation of the SAGE spectrometer

    NASA Astrophysics Data System (ADS)

    Cox, D. M.; Konki, J.; Greenlees, P. T.; Hauschild, K.; Herzberg, R.-D.; Pakarinen, J.; Papadakis, P.; Rahkila, P.; Sandzelius, M.; Sorri, J.

    2015-06-01

    The SAGE spectrometer combines a Ge-detector array with a Si detector to allow simultaneous detection of ?-rays and electrons. A comprehensive GEANT4 simulation package of the SAGE spectrometer has been developed with the ability to simulate the expected datasets based on user input files. The measured performance of the spectrometer is compared to the results obtained from the simulations.

  2. Diffraction gratings used as identifying markers

    DOEpatents

    Deason, V.A.; Ward, M.B.

    1991-03-26

    A finely detailed diffraction grating is applied to an object as an identifier or tag which is unambiguous, difficult to duplicate, or remove and transfer to another item, and can be read and compared with prior readings with relative ease. The exact pattern of the diffraction grating is mapped by diffraction moire techniques and recorded for comparison with future readings of the same grating. 7 figures.

  3. Asymmetric three-beam binary optic grating

    NASA Technical Reports Server (NTRS)

    Kathman, Alan D.; Johnson, Eric G.; Scott, Miles L.

    1993-01-01

    Binary and diffractive optical components are finding many applications in optical systems and integrated optical devices. A recent application required the development of a two-dimensional diffraction grating to perform an asymmetric, three-beam fanout. In this paper, techniques are presented for the design of arbitrary fanout grating devices. Modeling and optimization processes are demonstrated for the three-beam grating. The counter-intuitive results of the initial design are discussed, and experimental data verifying performance are presented.

  4. Alpha Magnetic Spectrometer

    NASA Astrophysics Data System (ADS)

    Ting, Samuel

    2012-07-01

    The Alpha Magnetic Spectrometer (AMS) is a precision particle physics magnetic spectrometer designed to measure electrons, positrons, gamma rays and various nuclei and anti-nuclei from the cosmos up to TeV energy ranges. AMS weighs 7.5 tons and measures 5 meters by 4 meters by 3 meters. It contains 300,000 channels of electronics and 650 onboard microprocessors. It was delivered to the International Space Station onboard space shuttle Endeavour and installed on May 19, 2011. Since that time, more than 14 billion cosmic ray events have been collected. All the detectors function properly. At this moment, we are actively engaged in data analysis. AMS is an international collaboration involving 16 countries and 60 institutes. It took 16 years to construct and test. AMS is the only major physical science experiment on the International Space Station and will continue to collect data over the entire lifetime of the Space Station (10-20 years).

  5. Imaging Fourier Transform Spectrometer

    SciTech Connect

    Bennett, C.L.; Carter, M.R.; Fields, D.J.; Hernandez, J.

    1993-04-14

    The operating principles of an Imaging Fourier Transform Spectrometer (IFTS) are discussed. The advantages and disadvantages of such instruments with respect to alternative imaging spectrometers are discussed. The primary advantages of the IFTS are the capacity to acquire more than an order of magnitude more spectral channels than alternative systems with more than an order of magnitude greater etendue than for alternative systems. The primary disadvantage of IFTS, or FTS in general, is the sensitivity to temporal fluctuations, either random or periodic. Data from the IRIFTS (ir IFTS) prototype instrument, sensitive in the infrared, are presented having a spectral sensitivity of 0.01 absorbance units, a spectral resolution of 6 cm{sup {minus}1} over the range 0 to 7899 cm{sup {minus}1}, and a spatial resolution of 2.5 mr.

  6. Nanosecond time-resolved vacuum ultraviolet spectrometer for ion diode spectroscopy

    NASA Astrophysics Data System (ADS)

    Nash, T.; Noack, D.; Filuk, A. B.

    1993-09-01

    A 1-m normal incidence spectrometer has been modified for use as a diagnostic of ion diode plasmas. To improve instrumental sensitivity, an elliptical mirror images an anode surface plasma onto the entrance slit of an f/10 normal incidence spectrometer. The detector is a time-resolving copper iodide coated microchannel plate stripline framing camera with 60-?m resolution, limiting instrumental resolution to 1 Å with a 600 l/mm grating in first order. Reflectivity of optics and photoelectron efficiency limit the spectral range from 400 to 2000 Å. With a 600-l/mm grating the detector spans a 600-Å range. Applications of the instrument may include ion source divergence measurements from Doppler broadening, electric field measurements from Stark splittings or shifts, electron temperature from mean ionization state, and magnetic field measurements on high-power Z pinches from Zeeman splitting.

  7. Polarization Measurements on SUMI's TVLS Gratings

    NASA Technical Reports Server (NTRS)

    Kobayashi, K.; West, E. A.; Davis, J. M.; Gary, G. A.

    2007-01-01

    We present measurements of toroidal variable-line-space (TVLS) gratings for the Solar Ultraviolet Magnetograph Investigation (SUMI), currently being developed an the National Space Science and Technology Center (NSSTC). SUMI zs a spectro-polarimeter designed no measure magnetic fields in the solar chromosphere by observing two UV emission lines sensitive to magnetic fields, the C-IV line at 155nm and the Mg-II line at 280nm. The instrument uses a pair of TVLS gratings, to observe both linear polarizations simultaneously. Efficiency measurements were done on bare aluminum gratings and MgF2 coated gratings, at both linear polarizations.

  8. Developing ultrafast laser inscribed volume gratings

    NASA Astrophysics Data System (ADS)

    MacLachlan, David G.; Choudhury, Debaditya; Arriola, Alexander; Cunningham, Colin; Thomson, Robert R.; Kirkham, Andrew; Lee, David

    2014-07-01

    Due to their high efficiency and broad operational bandwidths, volume phase holographic gratings (VPHGs) are often the grating technology of choice for astronomical instruments, but current VPHGs exhibit a number of drawbacks including limits on their size, function and durability due to the manufacturing process. VPHGs are also generally made using a dichromated gelatine substrate, which exhibits reduced transmission at wavelengths longer than ~2.2 ?m, limiting their ability to operate further into the mid-infrared. An emerging alternative method of manufacturing volume gratings is ultrafast laser inscription (ULI). This technique uses focused ultrashort laser pulses to induce a localised refractive index modification inside the bulk of a substrate material. We have recently demonstrated that ULI can be used to create volume gratings for operation in the visible, near-infrared and mid-infrared regions by inscribing volume gratings in a chalcogenide glass. The direct-write nature of ULI may then facilitate the fabrication of gratings which are not restricted in terms of their size and grating profile, as is currently the case with gelatine based VPHGs. In this paper, we present our work on the manufacture of volume gratings in gallium lanthanum sulphide (GLS) chalcogenide glass. The gratings are aimed at efficient operation at wavelengths around 1 ?m, and the effect of applying an anti-reflection coating to the substrate to reduce Fresnel reflections is studied.

  9. Polarization Measurements on SUMI's TVLS Gratings

    NASA Technical Reports Server (NTRS)

    Kobayashi, K.; West, E. A.; Davis, J. M.; Gary, G. A.

    2007-01-01

    We present measurements of toroidal variable-line-space (TVLS) gratings for the Solar Ultraviolet Magnetograph Investigation (SUMI), currently being developed at the National Space Science and Technology Center (NSSTC). SUMI is a spectro-polarimeter designed to measure magnetic fields in the solar chromosphere by observing two UV emission lines sensitive to magnetic fields, the CIY line at 155nm and the MgII line at 280nm. The instrument uses a pair of TVLS gratings, to observe both linear polarizations simultaneously. Efficiency measurements were done on bare aluminum gratings and aluminum/MgF2 coated gratings, at both linear polarizations.

  10. Hybrid fiber Bragg grating\\/long period fiber grating sensor for strain\\/temperature discrimination

    Microsoft Academic Search

    H. J. Patrick; G. M. Williams; A. D. Kersey; J. R. Pedrazzani; A. M. Vengsarkar

    1996-01-01

    We demonstrate a novel sensor which uses the difference in strain and temperature response of fiber Bragg gratings and a long period fiber grating to discriminate between strain and temperature induced wavelength shifts. Sensor interrogation is performed entirely on the fiber Bragg grating reflection signals. Strain and temperature were simultaneously measured to ±9 ?strain and ±1.5°C over a wide range

  11. Cassini Plasma Spectrometer Investigation

    Microsoft Academic Search

    D. T. Young; J. J. Berthelier; M. Blanc; J. L. Burch; A. J. Coates; R. Goldstein; M. Grande; T. W. Hill; R. E. Johnson; V. Kelha; D. J. Mccomas; E. C. Sittler; K. R. Svenes; K. Szegö; P. Tanskanen; K. Ahola; D. Anderson; S. Bakshi; R. A. Baragiola; B. L. Barraclough; R. K. Black; S. Bolton; T. Booker; R. Bowman; P. Casey; F. J. Crary; D. Delapp; G. Dirks; N. Eaker; H. Funsten; J. D. Furman; J. T. Gosling; H. Hannula; C. Holmlund; H. Huomo; J. M. Illiano; P. Jensen; M. A. Johnson; D. R. Linder; T. Luntama; S. Maurice; K. P. Mccabe; K. Mursula; B. T. Narheim; J. E. Nordholt; A. Preece; J. Rudzki; A. Ruitberg; K. Smith; S. Szalai; M. F. Thomsen; K. Viherkanto; J. Vilppola; T. Vollmer; T. E. Wahl; M. Wüest; T. Ylikorpi; C. Zinsmeyer

    2004-01-01

    The Cassini Plasma Spectrometer (CAPS) will make comprehensive three-dimensional mass-resolved measurements of the full variety of plasma phenomena found in Saturn’s magnetosphere. Our fundamental scientific goals are to understand the nature of saturnian plasmas primarily their sources of ionization, and the means by which they are accelerated, transported, and lost. In so doing the CAPS investigation will contribute to understanding

  12. Study of Extra-Solar Planets with the Advanced Fiber Optic Echelle

    NASA Technical Reports Server (NTRS)

    Noyes, Robert W.; Boyce, Joseph M. (Technical Monitor)

    2002-01-01

    This is the final report of NASA Grant NAG5-7505, for 'Study of Extra-solar Planets with the Advanced Fiber Optic Echelle'. This program was funded in response to our proposal submitted under NASA NRA 97-OSS-06, with a total period of performance from June 1, 1998 through Feb 28 2002. Principal Investigator is Robert W. Noyes; co-Investigators are Sylvain G. Korzennik (SAO), Peter Niserison (SAO), and Timothy M. Brown (High Altitude Observatory). Since the start of this program we have carried out more than 30 observing runs, typically of 5 to 7 days duration. We obtained a total of around 2000 usable observations of about 150 stars, where a typical observation consists of 3 exposures of 10 minutes each. Using this data base we detected thc two additional planetary companions to the star Upsilon Andromedae. This detection was made independently of, and essentially simultaneously with, a similar detection by the Berkeley group (Marcy et al): the fact that two data sets were completely independent and gave essentially the same orbital parameters for this three-planet system gave a strong confirmation of this important result. We also extended our previous detection of the planet orbiting Rho Coronae Borealis to get a better determination of its orbital eccentricity: e=0.13 +/- 0.05. We detected a new planet in orbit around the star HD 89744, with orbital period 256 days, semi-major axis 0.88 AU, eccentricity 0.70, and minimum mass m sini = 7.2 m(sub Jup). This discovery is significant because of the very high orbital eccentricity, arid also because HD 89744 has both high metallicity [Fe/H] and at the same time a low [C/Fe] abundance ratio.

  13. Precise Radial Velocities with an Upgraded Advanced Fiber Optic Echelle (AFOE)

    NASA Astrophysics Data System (ADS)

    Walters, M. A.; Korzennik, S. G.; Nisenson, P.; Henry, G. W.

    2006-06-01

    The Advanced Fiber Optic Echelle (AFOE) has been used to make precise radial velocity (PRV) observations for some 12 years. The AFOE spectrograph was initially designed as a test-bed for PRV techniques for astroseismology and planet detection, and tried to provide both short term and long term stability. The resulting trade-offs between spectral resolution, range, and coverage led to a low efficiency design. In order to optimize PRVs obtained with the iodine cell technique, the spectrograph was recently upgraded, increasing the throughput and spectral coverage while reducing the maximum resolution and range. The instrument was also moved from the 60" Tillinghast telescope at the Fred Lawrence Whipple Observatory, located at Mt. Hopkins (AZ), to the 100" Hooker telescope, located at Mt. Wilson (CA). We describe the instrumental changes required for the spectrograph upgrade as well as those needed to accommodate the 100" telescope. As a result of the instrumental changes, the data configuration has changed significantly. One would like to be able to combine radial velocities obtained before the upgrade with those obtained after, but one must take care in doing so. We describe the methodology developed to allow us to use all of the PRVs together. We also detail the precision achieved for this technique, along with the inherent precision of the upgraded configuration. Finally, we present the radial velocities we have obtained for HD 185395 as an interesting example of our studies. This triple system shows large radial velocity variations. We compare the RV variations with observed photometric changes, and present period analyses for both data sets. This work is funded by NASA/JPL/SIM (subcontract no. 1259554).

  14. Distributed Bragg grating integrated-optical filters: Synthesis and fabrication

    E-print Network

    Murphy, Thomas E.

    is used to trans- fer the grating patterns to the top of the rib waveguides. Reactive ion etching is used grating-based filters, we have used a strip-loaded rib wave- guide geometry where a grating pattern

  15. Space-resolved extreme ultraviolet spectrometer for impurity emission profile measurement in Large Helical Device

    Microsoft Academic Search

    Chunfeng Dong; Shigeru Morita; Motoshi Goto; Hangyu Zhou

    2010-01-01

    A space-resolved extreme ultraviolet (EUV) spectrometer working in 60-400 A˚ range has been developed to observe impurity emission profiles in core and edge plasmas of Large Helical Device (LHD). A flat focus is made for plane surface detector by using a varied line spacing holographic grating with an angle of incidence of 87°. An excellent spectral resolution of 0.22 A˚

  16. Airborne VNIR and SWIR Imaging Spectrometer and its Multisensor Remote Sensing Applications

    Microsoft Academic Search

    Xiuhong Sun; James J. Baker; Patrick L. Coronado; Fran Stetina

    2006-01-01

    An Airborne VNIR and SWIR Imaging Spectrometer (AVSIS) system is fully integrated with grating-based VNIR and SWIR imaging spectrographs, a customized CCD camera and an InGaAs camera, a precision GPS\\/IMU setup, a specially- configured instrument PC, and a dedicated AVSIS operation autonomous software package. AVSIS is a fast hyperspectral imaging system capable of imaging simultaneously 129 spectral bands across a

  17. Progress toward a multiobject radial-velocity spectrometer

    NASA Astrophysics Data System (ADS)

    Lutz, Thomas E.; Ingerson, Thomas; Weller, William G.

    1987-12-01

    It is shown that it is possible to obtain stellar radial velocities of high accuracy using a fiber-fed echelle spectrograph with no cross disperser. Although the resulting spectrum contains many overlapping orders, the radial-velocity information is still present. Velocities may be obtained by cross correlation with reference data obtained with the same instrument. The accuracy is a function of the signal-to-noise ratio, and ranges from + or - 4 km/s to + or - 1 km/s. Velocities are obtained with exposure times just sufficient to obtain the barest trace of a spectrum using the same spectrograph and CCD detector with a cross disperser. Thus, it appears possible to obtain precision similar to that obtained with an order separator, but with considerably better sensitivity, due to a multiplexing gain. Moreover, the overlapping orders of the stellar spectrum only occupy a few rows of the CCD. Using a multiple-fiber-feed device, many such spectra could be fit on the CCD. This leads to the expectation of obtaining many radial velocities simultaneously using a multiobject spectrometer now under construction at Cerro Tololo.

  18. Tunable External Cavity Quantum Cascade Lasers (EC-QCL): an application field for MOEMS based scanning gratings

    NASA Astrophysics Data System (ADS)

    Grahmann, Jan; Merten, André; Ostendorf, Ralf; Fontenot, Michael; Bleh, Daniela; Schenk, Harald; Wagner, Hans-Joachim

    2014-03-01

    In situ process information in the chemical, pharmaceutical or food industry as well as emission monitoring, sensitive trace detection and biological sensing applications would increasingly rely on MIR-spectroscopic anal­ysis in the 3 ?m - 12 ?m wavelength range. However, cost effective, portable, low power consuming and fast spectrometers with a wide tuning range are not available so far. To provide these MIR-spectrometer properties, the combination of quantum cascade lasers with a MOEMS scanning grating as wavelength selective element in the external cavity is addressed to provide a very compact and fast tunable laser source for spectroscopic analysis.

  19. Tilt sensitivity of the two-grating interferometer

    SciTech Connect

    Anderson, Christopher N.; Naulleau, Patrick P.

    2008-01-30

    Fringe formation in the two-grating interferometer is analyzed in the presence of a small parallelism error between the diffraction gratings assumed in the direction of grating shear. Our analysis shows that with partially coherent illumination, fringe contrast in the interference plane is reduced in the presence of nonzero grating tilt with the effect proportional to the grating tilt angle and the grating spatial frequencies. Our analysis also shows that for a given angle between the gratings there is an angle between the final grating and the interference plane that optimizes fringe contrast across the field.

  20. Fiber optic diffraction grating maker

    DOEpatents

    Deason, Vance A. (Idaho Falls, ID); Ward, Michael B. (Idaho Falls, ID)

    1991-01-01

    A compact and portable diffraction grating maker comprised of a laser beam, optical and fiber optics devices coupling the beam to one or more evanescent beam splitters, and collimating lenses or mirrors directing the split beam at an appropriate photosensitive material. The collimating optics, the output ends of the fiber optic coupler and the photosensitive plate holder are all mounted on an articulated framework so that the angle of intersection of the beams can be altered at will without disturbing the spatial filter, collimation or beam quality, and assuring that the beams will always intersect at the position of the plate.

  1. III-Nitride grating grown on freestanding HfO2 gratings.

    PubMed

    Wang, Yongjin; Wu, Tong; Hu, Fangren; Kanamori, Yoshiaki; Zhu, Hongbo; Hane, Kazuhiro

    2011-01-01

    We report here the epitaxial growth of III-nitride material on freestanding HfO2 gratings by molecular beam epitaxy. Freestanding HfO2 gratings are fabricated by combining film evaporation, electron beam lithography, and fast atom beam etching of an HfO2 film by a front-side silicon process. The 60-?m long HfO2 grating beam can sustain the stress change during the epitaxial growth of a III-nitride material. Grating structures locally change the growth condition and vary indium composition in the InGaN/GaN quantum wells and thus, the photoluminescence spectra of epitaxial III-nitride grating are tuned. Guided mode resonances are experimentally demonstrated in fabricated III-nitride gratings, opening the possibility to achieve the interaction between the excited light and the grating structure through guided mode resonance.PACS: 78.55.Cr; 81.65.Cf; 81.15.Hi. PMID:21849084

  2. Coupled wave theory for thick hologram gratings

    Microsoft Academic Search

    Herwig Kogelnik

    1969-01-01

    A coupled wave analysis is given of the Bragg diffraction of light by thick hologram gratings, which is analogous to Phariseau's treatment of acoustic gratings and to the dynamical theory of X-ray diffraction. The theory remains valid for large diffraction efficiencies where the incident wave is strongly depleted. It is applied to transmission holograms and to reflection holograms. Spatial modulations

  3. Waveguide grating lenses for optical couplers

    Microsoft Academic Search

    Gen-ichi Hatakoshi; Harumi Fujima

    1984-01-01

    New waveguide grating lenses for coupling a guided wave to a spherical wave, focusing in the air, have been designed. The lenses have the advantages of high efficiency and high practicability for fabrication. Chirped and curved grating lenses were fabricated on PMMA waveguides by an electron beam exposure system.

  4. Application of MEMS blazed gratings in WDM

    NASA Astrophysics Data System (ADS)

    Wu, Yongfeng; Yu, Honglin; Kang, Zhiping

    2009-05-01

    For the shortage and limitation of ruled grating that have ghost lines and stray light because of period error and ruling irregularity, a method for making a wavelength division multiplexer (WDM) based on Micro Electro-Mechanical System (MEMS) blazed grating is proposed. The basic composition of WDM based on MEMS blazed grating is introduced according to the method. The process realizing MEMS blazed grating and means for improving diffraction efficiency are also introduced. MEMS blazed grating is numerical simulated and analyzed in laboratory virtual instrument engineering workbench (LabVIEW), the diffraction intensity distribution of blazed grating is presented, it is shown that the blazed grating, period is 2000nm and blazed angle is 20 degree, have the best division effect for light wave with wavelength about 1.55?m by the results. At the same time, the 3D layout of WDM is provided in ZEMAX, and the rays in WDM are traced also. It is indicated by the results when the channel spacing is greater than or equal to 50nm, the division effect is in evidence. It achieves the capability of Coarse Wavelength Division Multiplexing (CWDM). It is proved that MEMS blazed grating can be applied well in WDM by all the results.

  5. Grating enhanced external cavity diode laser

    Microsoft Academic Search

    A. Wicht; M. Rudolf; P. Huke; R.-H. Rinkleff; K. Danzmann

    2004-01-01

    We describe a concept for diode lasers with optical feedback. It is based on the combination of two different diode laser concepts: the diode laser with (i) feedback from a grating and (ii) resonant optical feedback from a separate cavity. The goal of our work is to unite the excellent tunability and well known reliability of grating diode lasers with

  6. Fiber Bragg grating impulsive pressure sensor

    Microsoft Academic Search

    Zdzislaw Kaczmarek

    2005-01-01

    A new impulsive pressure sensor based on the elastic bar, is presented in this paper. As the elastic bar a piece of single mode optical fiber with photo-inscribed Bragg gratings is used. The grating is an optical strain gauge that converts the stress waves in the fiber into the changes of the Bragg wavelength. Experimental setup for the proposed sensor

  7. Long-period gratings in chalcogenide fibers.

    PubMed

    Pudo, Dominik; Mägi, Eric C; Eggleton, Benjamin J

    2006-05-01

    We report the first demonstration of long period gratings in single mode As(2)Se(3) chalcogenide glass fiber. The grating is implemented by pressing a threaded rod against a short piece of fiber. Its strength can be tuned over a 25 dB range, has high repeatability, and is fully reversible. PMID:19516523

  8. Pitch evaluation of high-precision gratings

    NASA Astrophysics Data System (ADS)

    Lu, Yancong; Zhou, Changhe; Wei, Chunlong; Jia, Wei; Xiang, Xiansong; Li, Yanyang; Yu, Junjie; Li, Shubin; Wang, Jin; Liu, Kun; Wei, Shengbin

    2014-11-01

    Optical encoders and laser interferometers are two primary solutions in nanometer metrology. As the precision of encoders depends on the uniformity of grating pitches, it is essential to evaluate pitches accurately. We use a CCD image sensor to acquire grating image for evaluating the pitches with high precision. Digital image correlation technique is applied to filter out the noises. We propose three methods for determining the pitches of grating with peak positions of correlation coefficients. Numerical simulation indicated the average of pitch deviations from the true pitch and the pitch variations are less than 0.02 pixel and 0.1 pixel for these three methods when the ideal grating image is added with salt and pepper noise, speckle noise, and Gaussian noise. Experimental results demonstrated that our method can measure the pitch of the grating accurately, for example, our home-made grating with 20?m period has 475nm peak-to-valley uniformity with 40nm standard deviation during 35mm range. Another measurement illustrated that our home-made grating has 40nm peak-to-valley uniformity with 10nm standard deviation. This work verified that our lab can fabricate high-accuracy gratings which should be interesting for practical application in optical encoders.

  9. Elemental abundance analyses with Complejo Astronomico EL Leoncito REOSC echelle spectrograms. III. HR 4487, 14 Hydrae, and 3 Centauri A

    NASA Astrophysics Data System (ADS)

    Pintado, O. I.; Adelman, S. J.; Gulliver, A. F.

    1998-05-01

    Using CASLEO echelle spectrograms, elemental abundances are derived for the sharp-lined non-magnetic CP stars HR 4487, 14 Hya, and 3 Cen A. The first two stars are members of the Mercury-Manganese subgroup and have abundances which are similar to other such peculiar stars. The third is a hotter related star. The detection of Mn II lines in its spectrum adds to this relationship. Table 3 is avaible electronically vit the CDS via anonymous ftp 130.79.128.5 or http://cdsweb.u-strasbg.fr/Abstract.html.

  10. The GRANIT spectrometer

    SciTech Connect

    Baessler, Stefan [ORNL; Beau, M [ Inst Max Von Laue Paul Langevin, F-38042 Grenoble 9, France; Kreuz, Michael [ Inst Max Von Laue Paul Langevin, F-38042 Grenoble 9, France; Nesvizhevsky, V. [ Inst Max Von Laue Paul Langevin, F-38042 Grenoble 9, France; Kurlov, V [Institute of Solid State Physics, Russian Ac. Sci., Chernogolovka, Moscow, Russi; Pignol, G [LPSC IN2P3 UJF INPG, R-38026 Grenoble, France; Protasov, K. [LPSC IN2P3 UJF INPG, R-38026 Grenoble, France; Vezzu, Francis [LPSC IN2P3 UJF INPG, R-38026 Grenoble, France; Voronin, Vladimir [Institute of Metal Physics, Russia

    2011-01-01

    The existence of quantum states of matter in a gravitational field was demonstrated recently in the Institut Laue-Langevin (ILL), Grenoble, in a series of experiments with ultra cold neutrons (UCN). UCN in low quantum states is an excellent probe for fundamental physics, in particular for constraining extra short-range forces; as well as a tool in quantum optics and surface physics. The GRANIT is a follow-up project based on a second-generation spectrometer with ultra-high energy resolution, permanently installed in ILL. It has been constructed in framework of an ANR grant; and will become operational in 2011.

  11. Neutron range spectrometer

    DOEpatents

    Manglos, S.H.

    1988-03-10

    A neutron range spectrometer and method for determining the neutron energy spectrum of a neutron emitting source are disclosed. Neutrons from the source are colliminated along a collimation axis and a position sensitive neutron counter is disposed in the path of the collimated neutron beam. The counter determines positions along the collimation axis of interactions between the neutrons in the neutron beam and a neutron-absorbing material in the counter. From the interaction positions, a computer analyzes the data and determines the neutron energy spectrum of the neutron beam. The counter is preferably shielded and a suitable neutron-absorbing material is He-3. 1 fig.

  12. Wavelet element method for lamellar gratings.

    PubMed

    Liu, Zhangyi; Wu, Jiu Hui; Shen, Li

    2013-05-01

    A wavelet element method is developed for analyzing lamellar diffraction gratings or grating stacks. The eigenmodes of the grating layers are accurately calculated by this method, and then the diffraction efficiencies of the gratings are calculated by the S-matrix algorithm. The method proposed in this paper consists in mapping each homogeneous layer to a wavelet element, and then matching them according to the boundary conditions between the layers. By this method the boundary conditions are satisfied rigorously and the Gibbs phenomenon in the Fourier modal method (FMM) can be avoided. The method performs better than the standard FMM for gratings involving metals. It can also be applied to analyze other discontinuous structures. PMID:23695336

  13. The design and simulation of single detector MIR spectrometer based on MEMS scanning mirror

    NASA Astrophysics Data System (ADS)

    Zhang, Zhong-wei; Wen, Zhi-yu; Zeng, Tian-ling; Wei, Kang-lin

    2011-08-01

    Infrared (IR) spectrometers are very important optical equipments that can be used in industry, science, medicine, agriculture, biology and food safety etc., and the market is growing. However, most traditional IR spectrometers, such as Fourier transform spectrometer (FTS) that based on Michelson interferometer principle and scanning monochromator that based on grating scanning, are expensive, relative large volume, and stationary, which can't meet the requirements of specific application such as rapidity, special environment and some special samples. To overcome these drawbacks, innovatory technology-micro electro mechanical systems (MEMS) technology was used in micro IR spectrometers in the past few years. And several prototypes and products that based on several operational principles have been emerged. In this paper, a novel IR micro spectrometer which based on MEMS technology and used single element detector was presented over a wide spectral range (from 2500nm to 5000nm) in the mid infrared (MIR) wavelength regime, and the optical system of it was designed on the basis of traditional scanning monochromator principle. In the optical system, there is a highlighted characteristic that dual spherical focus mirror was used to focus the diffraction light of the diffraction grating, which improved the spectral resolution of the optical system. Finally, using Zemax optical software, three torsion angle locations were selected to simulate the optical system of the spectrometer with the slit's size 0.1mm×1mm. The simulation result indicated that in the whole wavelength range the spectral resolution of the optical system was less than 30nm, and a high accuracy MIR spectrometer with compact volume will be realized in future hopefully.

  14. CCMR: Vertical Coupling Grating Design

    NSDL National Science Digital Library

    Estelle, Adam

    2007-08-29

    Since the conception of fiber-optic communication, much research has been focused on creating a more efficient and less costly means of transporting information using light signals. Photonic integrated circuits (PIC), which are analogous to electronic integrated circuits used in everyday electronics, combine numerous optical principles to facilitate the transfer of light information. A specific setback in optical information transfer is the joining of optical fibers to the PICs. Light is directed in the PIC through small channels known as waveguides which are considerably smaller than the optical fibers. Many methods have been suggested for joining fibers and PICs. Loss of light caused by reflection, scattering, and other phenomena must be minimized at the junction. Numerous suggested methods make it difficult and expensive to package the final combination of fiber and chip. One such method uses a grating that can direct light into the waveguide from a fiber aligned perpendicular to the PIC without the need for additional optical devices or cumbersome fastening methods. By altering the grating dimensions with the help of an evolutionary algorithm, coupling efficiency could potentially be very high. This simple coupling method would greatly cut packaging costs making the design very appealing for mass market applications.

  15. Arcus: The next generation of high-resolution X-ray grating spectra

    NASA Astrophysics Data System (ADS)

    Smith, Randall

    2014-11-01

    We present the design and scientific motivation for Arcus, an X-ray grating spectrometer mission to be deployed on the International Space Station. This mission will observe structure formation at and beyond the edges of clusters and galaxies, feedback from supermassive black holes, the structure of the interstellar medium and the formation and evolution of stars. Key mission requirements will be R>2500 and >600 cm^2 of effective area at the crucial O VII and O VIII lines, with the full bandpass going from 8-52Å, with an overall minimum resolution of 1300 and effective area >150 cm^2. We will use the silicon pore optics proposed for ESA's Athena mission, paired with off-plane gratings being developed at the University of Iowa and combined with MIT/Lincoln Labs CCDs.

  16. High-resolution imaging spectrometer for recording absolutely calibrated far ultraviolet spectra from laser-produced plasmas.

    PubMed

    Brown, Charles M; Seely, John F; Feldman, Uri; Holland, Glenn E; Weaver, James L; Obenschain, Steven P; Kjornrattanawanich, Benjawan; Fielding, Drew

    2008-10-01

    An imaging spectrometer was designed and fabricated for recording far ultraviolet spectra from laser-produced plasmas with wavelengths as short as 155 nm. The spectrometer implements a Cassegrain telescope and two gratings in a tandem Wadsworth optical configuration that provides diffraction limited resolution. Spectral images were recorded from plasmas produced by the irradiation of various target materials by intense KrF laser radiation with 248 nm wavelength. Two pairs of high-resolution gratings can be selected for the coverage of two wavebands, one grating pair with 1800 grooves/mm and covering approximately 155-175 nm and another grating pair with 1200 grooves/mm covering 230-260 nm. The latter waveband includes the 248 nm KrF laser wavelength, and the former waveband includes the wavelength of the two-plasmon decay instability at 23 the KrF laser wavelength (165 nm). The detection media consist of a complementary metal oxide semiconductor imager, photostimulable phosphor image plates, and a linear array of 1 mm(2) square silicon photodiodes with 0.4 ns rise time. The telescope mirrors, spectrometer gratings, and 1 mm(2) photodiode were calibrated using synchrotron radiation, and this enables the measurement of the absolute emission from the laser-produced plasmas with temporal, spatial, and spectral resolutions. The spectrometer is capable of measuring absolute spectral emissions at 165 nm wavelength as small as 5x10(-7) J/nm from a plasma source area of 0.37 mm(2) and with 0.4 ns time resolution. PMID:19044704

  17. High-resolution imaging spectrometer for recording absolutely calibrated far ultraviolet spectra from laser-produced plasmas

    NASA Astrophysics Data System (ADS)

    Brown, Charles M.; Seely, John F.; Feldman, Uri; Holland, Glenn E.; Weaver, James L.; Obenschain, Steven P.; Kjornrattanawanich, Benjawan; Fielding, Drew

    2008-10-01

    An imaging spectrometer was designed and fabricated for recording far ultraviolet spectra from laser-produced plasmas with wavelengths as short as 155 nm. The spectrometer implements a Cassegrain telescope and two gratings in a tandem Wadsworth optical configuration that provides diffraction limited resolution. Spectral images were recorded from plasmas produced by the irradiation of various target materials by intense KrF laser radiation with 248 nm wavelength. Two pairs of high-resolution gratings can be selected for the coverage of two wavebands, one grating pair with 1800 grooves/mm and covering approximately 155-175 nm and another grating pair with 1200 grooves/mm covering 230-260 nm. The latter waveband includes the 248 nm KrF laser wavelength, and the former waveband includes the wavelength of the two-plasmon decay instability at 23 the KrF laser wavelength (165 nm). The detection media consist of a complementary metal oxide semiconductor imager, photostimulable phosphor image plates, and a linear array of 1 mm2 square silicon photodiodes with 0.4 ns rise time. The telescope mirrors, spectrometer gratings, and 1 mm2 photodiode were calibrated using synchrotron radiation, and this enables the measurement of the absolute emission from the laser-produced plasmas with temporal, spatial, and spectral resolutions. The spectrometer is capable of measuring absolute spectral emissions at 165 nm wavelength as small as 5×10-7 J/nm from a plasma source area of 0.37 mm2 and with 0.4 ns time resolution.

  18. A novel dual-detector micro-spectrometer

    NASA Astrophysics Data System (ADS)

    Otto, Thomas; Saupe, Ray; Stock, Volker; Bruch, Reinhard; Gruska, Bernd; Gessner, Thomas

    2005-01-01

    Infrared analysis is a well-established tool for measuring composition and purity of various materials in industrial-, medical- and environmental applications. Traditional spectrometers, for example Fourier Transform Infrared (FTIR) Instruments are mainly designed for laboratory use and are generally, too large, heavy, costly and delicate to handle for remote applications. With important advances in the miniaturization, ruggedness and cost efficiency we have designed and created a new type of a micromirror spectrometer that can operate in harsh temperature and vibrating environments This device is ideally suited for environmental monitoring, chemical and biological applications as well as detection of biological warfare agents and sensing in important security locations In order to realize such compact, portable and field-deployable spectrometers we have applied MOEMS technology. Thus our novel dual detector micro mirror system is composed of a scanning micro mirror combined with a diffraction grating and other essential optical components in order to miniaturize the basic modular set-up. Especially it periodically disperses polychromatic radiation into its spectral components, which are measured by a combination of a visible (VIS) and near infrared (NIR) single element detector. By means of integrated preamplifiers high-precise measurements over a wide dynamic wavelength range are possible. In addition the spectrometer, including the radiation source, detectors and electronics can be coupled to a minimum-volume liquid or gas-flow cell. Furthermore a SMA connector as a fiber optical input allows easy attachment of fiber based probes. By utilizing rapid prototyping techniques, where all components are directly integrated, the micro mirror spectrometer is manufactured for the 700-1700 nm spectral range. In this work the advanced optical design and integration of the electronic interface will be reviewed. Furthermore we will demonstrate the performance of the system and present characteristic measurement results. Finally advanced packaging issues and test results of the device will be discussed.

  19. Optical characteristics of a hybrid fiber grating based on a surface long-period grating incorporating a fiber Bragg grating

    NASA Astrophysics Data System (ADS)

    Kim, Hyun-Joo; Jun, Na-Ram; Han, Young-Geun

    2012-11-01

    A hybrid grating based on a surface long-period grating (SLPG) incorporating a fiber Bragg grating (FBG) was proposed, and its optical characteristics were experimentally investigated by changing the external temperature and the ambient refractive index. For the fabrication of the hybrid grating, a FBG was firstly fabricated by using a beam scanning technique with a frequency-doubled Ar+ laser; then, some portion of the cladding region without the FBG was removed by using a side polishing technique. The SLPG was formed on a flat surface of the side-polished fiber (D-shaped fiber) by using a standard contact lithography technique. The transmission spectrum of the hybrid grating was superimposed on those for the SLPG and the FBG. Variations in the external refractive index and the temperature modified the transmission characteristics of the proposed hybrid grating. The ambient index sensitivity of the resonant peak induced by the SLPG was measured to be 810.7 nm/RIU while the resonant peak generated by the FBG was kept constant as the ambient index changed in the index range from 1.30 to 1.45. The temperature sensitivities of two resonant peaks for the SLPG and the FBG were measured to be -0.52 nm/°C and 0.01 nm/°C, respectively. Accordingly, we expect discrimination between two concurrent sensitivities, such as the external refractive index and the temperature sensitivities, to be possible when the hybrid fiber grating is implemented.

  20. Resonant ultrasound spectrometer

    DOEpatents

    Migliori, Albert (Santa Fe, NM); Visscher, William M. (Los Alamos, NM); Fisk, Zachary (Santa Fe, NM)

    1990-01-01

    An ultrasound resonant spectrometer determines the resonant frequency spectrum of a rectangular parallelepiped sample of a high dissipation material over an expected resonant response frequency range. A sample holder structure grips corners of the sample between piezoelectric drive and receive transducers. Each transducer is mounted on a membrane for only weakly coupling the transducer to the holder structure and operatively contacts a material effective to remove system resonant responses at the transducer from the expected response range. i.e., either a material such as diamond to move the response frequencies above the range or a damping powder to preclude response within the range. A square-law detector amplifier receives the response signal and retransmits the signal on an isolated shield of connecting cabling to remove cabling capacitive effects. The amplifier also provides a substantially frequency independently voltage divider with the receive transducer. The spectrometer is extremely sensitive to enable low amplitude resonance to be detected for use in calculating the elastic constants of the high dissipation sample.

  1. Prototype Neutron Energy Spectrometer

    SciTech Connect

    Stephen Mitchell, Sanjoy Mukhopadhyay, Richard Maurer, Ronald Wolff

    2010-06-16

    The project goals are: (1) Use three to five pressurized helium tubes with varying polyethylene moderators to build a neutron energy spectrometer that is most sensitive to the incident neutron energy of interest. Neutron energies that are of particular interest are those from the fission neutrons (typically around 1-2 MeV); (2) Neutron Source Identification - Use the neutron energy 'selectivity' property as a tool to discriminate against other competing processes by which neutrons are generated (viz. Cosmic ray induced neutron production [ship effect], [a, n] reactions); (3) Determine the efficiency as a function of neutron energy (response function) of each of the detectors, and thereby obtain the composite neutron energy spectrum from the detector count rates; and (4) Far-field data characterization and effectively discerning shielded fission source. Summary of the presentation is: (1) A light weight simple form factor compact neutron energy spectrometer ready to be used in maritime missions has been built; (2) Under laboratory conditions, individual Single Neutron Source Identification is possible within 30 minutes. (3) Sources belonging to the same type of origin viz., (a, n), fission, cosmic cluster in the same place in the 2-D plot shown; and (4) Isotopes belonging to the same source origin like Cm-Be, Am-Be (a, n) or Pu-239, U-235 (fission) do have some overlap in the 2-D plot.

  2. Improved multiple-pass Raman spectrometer

    NASA Astrophysics Data System (ADS)

    Kc, Utsav; Silver, Joel A.; Hovde, David C.; Varghese, Philip L.

    2011-08-01

    An improved Raman gain spectrometer for flame measurements of gas temperature and species concentrations is described. This instrument uses a multiple-pass optical cell to enhance the incident light intensity in the measurement volume. The Raman signal is 83 times larger than from a single pass, and the Raman signal-to-noise ratio (SNR) in room-temperature air of 153 is an improvement over that from a single-pass cell by a factor of 9.3 when the cell is operated with 100 passes and the signal is integrated over 20 laser shots. The SNR improvement with the multipass cell is even higher for flame measurements at atmospheric pressure, because detector readout noise is more significant for single-pass measurements when the gas density is lower. Raman scattering is collected and dispersed in a spectrograph with a transmission grating and recorded with a fast gated CCD array detector to help eliminate flame interferences. The instrument is used to record spontaneous Raman spectra from N2, CO2, O2, and CO in a methane--air flame. Curve fits of the recorded Raman spectra to detailed simulations of nitrogen spectra are used to determine the flame temperature from the shapes of the spectral signatures and from the ratio of the total intensities of the Stokes and anti-Stokes signals. The temperatures measured are in good agreement with radiation-corrected thermocouple measurements for a range of equivalence ratios.

  3. Michelle, mid-infrared spectrometer and imager

    NASA Astrophysics Data System (ADS)

    Bryson, Ian R.; Glasse, Alistair C.; Atad-Ettedgui, Eli I.

    1994-06-01

    Michelle is a facility-class long-slit spectrometer for the mid- IR being built at the Royal Observatory Edinburgh for the UK Infrared Telescope (UKIRT). With diamond turned, all-reflective optics to achieve high throughput and a cryogenic mechanism to select one from five diffraction gratings during operation, it will be capable of taking spectra at resolving powers ranging from 100 to 30,000 over wavelengths from 8 to 25 micrometers . A separate optical path will provide the ability to switch in well under a minute from spectroscopy to taking fully sampled diffraction limited images of the same field. Two mechanical coolers will maintain its optics at below 25K, while a Joule- Thomson (JT) stage on one of the coolers will keep the Si:As hybrid detector array at less than 10K. We present the predicted performance of the instrument, along with its opto-mechanical layout and the means by which it can be easily converted for use on the proposed Gemini telescope. The design of some unusual mechanisms is discussed.

  4. Fabricating Radial Groove Gratings Using Projection Photolithography

    NASA Technical Reports Server (NTRS)

    Iazikov, Dmitri; Mossberg, Thomas W.

    2009-01-01

    Projection photolithography has been used as a fabrication method for radial grove gratings. Use of photolithographic method for diffraction grating fabrication represents the most significant breakthrough in grating technology in the last 60 years, since the introduction of holographic written gratings. Unlike traditional methods utilized for grating fabrication, this method has the advantage of producing complex diffractive groove contours that can be designed at pixel-by-pixel level, with pixel size currently at the level of 45 45 nm. Typical placement accuracy of the grating pixels is 10 nm over 30 nm. It is far superior to holographic, mechanically ruled or direct e-beam written gratings and results in high spatial coherence and low spectral cross-talk. Due to the smooth surface produced by reactive ion etch, such gratings have a low level of randomly scattered light. Also, due to high fidelity and good surface roughness, this method is ideally suited for fabrication of radial groove gratings. The projection mask is created using a laser writer. A single crystal silicon wafer is coated with photoresist, and then the projection mask, with its layer of photoresist, is exposed for patterning in a stepper or scanner. To develop the photoresist, the fabricator either removes the exposed areas (positive resist) of the unexposed areas (negative resist). Next, the patterned and developed photoresist silicon substrate is subjected to reactive ion etching. After this step, the substrate is cleaned. The projection mask is fabricated according to electronic design files that may be generated in GDS file format using any suitable CAD (computer-aided design) or other software program. Radial groove gratings in off-axis grazing angle of incidence mount are of special interest for x-ray spectroscopy, as they allow achieving higher spectral resolution for the same grating area and have lower alignment tolerances than traditional in-plane grating scheme. This is especially critical for NASA Constellation- X project that will utilize hundreds of gratings all of which need to be precisely aligned for x-ray observation of space.

  5. The chemical composition of the Galactic regions M8 and M17. A revision based on deep VLT echelle spectrophotometry

    E-print Network

    J. Garcia-Rojas; C. Esteban; A. Peimbert; M. Rodriguez; M. Peimbert; M. T. Ruiz

    2006-10-03

    We present new echelle spectrophotometry of the Galactic H II regions M8 and M17. The data have been taken with the VLT UVES echelle spectrograph in the 3100 to 10400 angstroms range. We have measured the intensities of 375 and 260 emission lines in M8 and M17 respectively, increasing significatively the number of emission lines measured in previous spectrophotometric studies of these nebulae. Most of the detected lines are permitted lines. Electron temperatures and densities have been determined using different diagnostics. We have derived He+, C++, O+ and O++ ionic abundances from pure recombination lines. We have also derived abundances from collisionally excited lines for a large number of ions of different elements. Highly consistent estimations of t2 have been obtained by using different independent indicators, the values are moderate and very similar to those obtained in other Galactic H II regions. We report the detection of deuterium Balmer emission lines, up to D$\\epsilon$, in M8 and show that their intensities are consistent with continuum fluorescence as their main excitation mechanism.

  6. Nano-Fabricated Gratings for Electrons

    NASA Astrophysics Data System (ADS)

    Gronniger, Glen; Gao, Hong; Freimund, Dan; Batelaan, Herman

    2003-05-01

    This work utilizes a free-standing material grating for electron diffraction. The material grating is made of silicon nitride and coated with a 2.3 nm (plus or minus 0.3 nm) layer of gold and palladium. The grating has a periodicity of 100 nm and was fabricated at MIT. The diffraction of electrons was observed with well resolved diffraction peaks. Diffraction was not observed using an uncoated silicon nitride grating. Building an electron interferometer utilizing the grating has also been explored. A 12 micron gold wire used as a bi-prism was combined with the grating. It was observed that applying a voltage to the wire while it was between the diffracted beams, allowed separation of the diffraction peaks to increase from 230 microns to 1 mm. This could be a large angle coherent beam splitter for electrons. However, we have not yet succeeded in making an electron interferometer with this arrangement. We are currently exploring a three grating Mach-Zehnder type electron interferometer. Work supported by NSF, DOD-EPSCoR

  7. Diffraction Grating Structures in Solar Cells

    SciTech Connect

    ZAIDI,SALEEM H.; GEE,JAMES M.; RUBY,DOUGLAS S.

    2000-12-01

    Sub-wavelength periodic texturing (gratings) of crystalline-silicon (c-Si) surfaces for solar cell applications can be designed for maximizing optical absorption in thin c-Si films. We have investigated c-Si grating structures using rigorous modeling, hemispherical reflectance, and internal quantum efficiency measurements. Model calculations predict almost {approximately}100% energy coupling into obliquely propagating diffraction orders. By fabrication and optical characterization of a wide range of 1D & 2D c-Si grating structures, we have achieved broad-band, low ({approximately} 5%) reflectance without an anti-reflection film. By integrating grating structures into conventional solar cell designs, we have demonstrated short-circuit current density enhancements of 3.4 and 4.1 mA/cm{sup 2} for rectangular and triangular 1D grating structures compared to planar controls. The effective path length enhancements due to these gratings were 2.2 and 1.7, respectively. Optimized 2D gratings are expected to have even better performance.

  8. Manufacture and development of multilayer diffraction gratings

    NASA Astrophysics Data System (ADS)

    Keck, J.; Oliver, J. B.; Kessler, T. J.; Huang, H.; Barone, J.; Hettrick, J.; Rigatti, A. L.; Hoover, T.; Marshall, K. L.; Schmid, A. W.; Kozlov, A.; Kosc, T. Z.

    2005-12-01

    The OMEGA EP Facility includes two high-energy, short-pulse laser beams that will be focused to high intensity in the OMEGA target chamber, providing backlighting of compressed fusion targets and investigating the fast-ignition concept. To produce 2.6-kJ output energy per beam, developments in grating compressor technology are required. Gold-coated diffraction gratings limit on-target energy because of their low damage fluence. Multilayer dielectric (MLD) gratings have shown promise as high-damage-threshold, high-efficiency diffraction gratings suitable for use in high-energy chirped-pulse amplification [ B. W. Shore et al., J. Opt. Soc. Am. A 14, 1124 (1997).] Binary 100-mm-diam MLD gratings have been produced at the Laboratory for Laser Energetics (LLE) using large-aperture, holographic exposure and reactive ion-beam etching systems. A diffraction efficiency of greater than 99.5% at 1053 nm has been achieved for gratings with 1740 grooves/mm, with a 1:1 damage threshold of 5.49 J/cm2 diffracted beam fluence at 10 ps. To demonstrate the ability to scale up to larger substrates, several 100-mm substrates have been distributed over an aperture of 47 × 43 cm and successfully etched, resulting in high efficiency over the full aperture. This paper details the manufacture and development of these gratings, including the specifics of the MLD coating, holographic lithography, reactive ion etching, reactive ion-beam cleaning, and wet chemical cleaning.

  9. A quantitative mode-resolved frequency comb spectrometer.

    PubMed

    Hébert, Nicolas Bourbeau; Scholten, Sarah K; White, Richard T; Genest, Jérôme; Luiten, Andre N; Anstie, James D

    2015-06-01

    We have developed a frequency-comb spectrometer that records 35-nm (4 THz) spectra with 2-pm (250 MHz) spectral sampling and an absolute frequency accuracy of 2 kHz. We achieve a signal-to-noise ratio of ~400 in a measurement time of 8.2 s. The spectrometer is based on a commercial frequency comb decimated by a variable-length, low-finesse Fabry Pérot filter cavity to fully resolve the comb modes as imaged by a virtually imaged phased array (VIPA), diffraction grating and near-IR camera. By tuning the cavity length, spectra derived from all unique decimated combs are acquired and then interleaved to achieve frequency sampling at the comb repetition rate of 250 MHz. We have validated the performance of the spectrometer by comparison with a previous high-precision absorption measurement of H13C14N near 1543 nm. We find excellent agreement, with deviations from the expected line centers and widths of, at most, 1 pm (125 MHz) and 3 pm (360 MHz), respectively. PMID:26072768

  10. SPICE EUV spectrometer for the Solar Orbiter mission

    NASA Astrophysics Data System (ADS)

    Fludra, A.; Griffin, D.; Caldwell, M.; Eccleston, P.; Cornaby, J.; Drummond, D.; Grainger, W.; Greenway, P.; Grundy, T.; Howe, C.; McQuirk, C.; Middleton, K.; Poyntz-Wright, O.; Richards, A.; Rogers, K.; Sawyer, C.; Shaughnessy, B.; Sidher, S.; Tosh, I.; Beardsley, S.; Burton, G.; Marshall, A.; Waltham, N.; Woodward, S.; Appourchaux, T.; Philippon, A.; Auchere, F.; Buchlin, E.; Gabriel, A.; Vial, J.-C.; Schühle, U.; Curdt, W.; Innes, D.; Meining, S.; Peter, H.; Solanki, S.; Teriaca, L.; Gyo, M.; Büchel, V.; Haberreiter, M.; Pfiffner, D.; Schmutz, W.; Carlsson, M.; Haugan, S. V.; Davila, J.; Jordan, P.; Thompson, W.; Hassler, D.; Walls, B.; Deforest, C.; Hanley, J.; Johnson, J.; Phelan, P.; Blecha, L.; Cottard, H.; Paciotti, G.; Autissier, N.; Allemand, Y.; Relecom, K.; Munro, G.; Butler, A.; Klein, R.; Gottwald, A.

    2013-09-01

    SPICE is a high resolution imaging spectrometer operating at extreme ultraviolet wavelengths, 70.4 - 79.0 nm and 97.3 - 104.9 nm. It is a facility instrument on the Solar Orbiter mission. SPICE will address the key science goals of Solar Orbiter by providing the quantitative knowledge of the physical state and composition of the plasmas in the solar atmosphere, in particular investigating the source regions of outflows and ejection processes which link the solar surface and corona to the heliosphere. By observing the intensities of selected spectral lines and line profiles, SPICE will derive temperature, density, flow and composition information for the plasmas in the temperature range from 10,000 K to 10MK. The instrument optics consists of a single-mirror telescope (off-axis paraboloid operating at near-normal incidence), feeding an imaging spectrometer. The spectrometer is also using just one optical element, a Toroidal Variable Line Space grating, which images the entrance slit from the telescope focal plane onto a pair of detector arrays, with a magnification of approximately x5. Each detector consists of a photocathode coated microchannel plate image intensifier, coupled to active-pixel-sensor (APS). Particular features of the instrument needed due to proximity to the Sun include: use of dichroic coating on the mirror to transmit and reject the majority of the solar spectrum, particle-deflector to protect the optics from the solar wind, and use of data compression due to telemetry limitations.

  11. High-resolution and broadband all-fiber spectrometers

    E-print Network

    Redding, Brandon; Seifert, Martin; Cao, Hui

    2014-01-01

    The development of optical fibers has revolutionized telecommunications by enabling long-distance broad-band transmission with minimal loss. In turn, the ubiquity of high-quality low-cost fibers enabled a number of additional applications, including fiber sensors, fiber lasers, and imaging fiber bundles. Recently, we showed that a mutlimode optical fiber can also function as a spectrometer by measuring the wavelength-dependent speckle pattern formed by interference between the guided modes. Here, we reach a record resolution of 1 pm at wavelength 1500 nm using a 100 meter long multimode fiber, outperforming the state-of-the-art grating spectrometers. we also achieved broad-band operation with a 4 cm long fiber, covering 400 nm - 750 nm with 1 nm resolution. The fiber spectrometer, consisting of the fiber which can be coiled to a small volume and a monochrome camera that records the speckle pattern, is compact, lightweight, and low cost while providing ultrahigh resolution, broad bandwidth and low loss.

  12. Development of grating light reflection spectroscopy for chemical sensing applications

    Microsoft Academic Search

    Sean Acie Smith

    2000-01-01

    Grating Light Reflection Spectroscopy (GLRS) exploits the interaction of light with a transmission diffraction grating in contact with a sample. With this technique, light reflected from the grating exhibits a redistribution of spectral intensity and phase dependent upon the bulk dielectric properties (refractive index and absorbance) of the sample. The use of a transmission diffraction grating makes GLRS unique within

  13. Superluminal pulse propagation in linear and nonlinear photonic grating structures

    Microsoft Academic Search

    Stefano Longhi; Marcello Marano; Michele Belmonte; Paolo Laporta

    2003-01-01

    Optical pulse propagation in photonic grating structures can show anomalous (i.e., superluminal or negative) group velocities under certain circumstances owing to the anomalous dispersive properties induced by the periodic grating structure. Such phenomena can be observed for either linear pulse propagation in passive dielectric grating structures, such as in fiber Bragg gratings (FBGs), as well as in frequency-conversion processes exploiting

  14. Phasor Analysis of Binary Diffraction Gratings with Different Fill Factors

    ERIC Educational Resources Information Center

    Martinez, Antonio; Sanchez-Lopez, Ma del Mar; Moreno, Ignacio

    2007-01-01

    In this work, we present a simple analysis of binary diffraction gratings with different slit widths relative to the grating period. The analysis is based on a simple phasor technique directly derived from the Huygens principle. By introducing a slit phasor and a grating phasor, the intensity of the diffracted orders and the grating's resolving…

  15. Fiber grating temperature demodulation system design of smart garment

    Microsoft Academic Search

    Li Zhenyu; Miao Changyun; Ye Chunqing; Song Huichao

    2010-01-01

    This paper studies the fiber grating temperature demodulation system of smart garment. Based on the analysis of fiber grating temperature sensing principle and the comparisons of the advantages and disadvantages of several common fiber grating demodulation method, this paper proposes a demodulation method of filter grating body temperature signal by using tunable Fabry-Perot (F-P) filter; This paper designs the optical

  16. Optoacoustic Solitons in Bragg Gratings

    NASA Astrophysics Data System (ADS)

    Tasgal, Richard S.; Band, Y. B.; Malomed, Boris A.

    2007-06-01

    Optical gap solitons, which exist due to a balance of nonlinearity and dispersion due to a Bragg grating, can couple to acoustic waves through electrostriction. This gives rise to a new species of “gap-acoustic” solitons (GASs), for which we find exact analytic solutions. The GAS consists of an optical pulse similar to the optical gap soliton, dressed by an accompanying phonon pulse. Close to the speed of sound, the phonon component is large. In subsonic (supersonic) solitons, the phonon pulse is a positive (negative) density variation. Coupling to the acoustic field damps the solitons’ oscillatory instability, and gives rise to a distinct instability for supersonic solitons, which may make the GAS decelerate and change direction, ultimately making the soliton subsonic.

  17. Broadband Liquid Dielectric Spectrometer

    NASA Astrophysics Data System (ADS)

    Chandra, Satyan; Arellano, Jesus; Mazzeo, Brian

    2009-10-01

    A dielectric spectrometer was built to measure the dielectric relaxation of proteins in solution. The dielectric cell consisted of two parallel stainless-steel electrodes (separation of 8.5 mm) embedded in PTFE. To provide temperature stability, thermally regulated water flowed through both electrodes. The cell was connected to a 4294A Precision Impedance Analyzer, providing impedance measurements from 40Hz to 110 MHz. Due to electrode polarization and high frequency parasitics, useful measurements were obtained for frequencies ranging from 10 kHz to 10 MHz. Calibration was performed using air, iso-propanol and deionized water. Experiments were also conducted on buffers and salt solutions. The dielectric relaxation of the protein beta-lactoglobulin was measured at mg/ml concentrations.

  18. Coastal Research Imaging Spectrometer

    NASA Technical Reports Server (NTRS)

    Lucey, Paul G.; Williams, Timothy; Horton, Keith A.

    2002-01-01

    The Coastal Research Imaging Spectrometer (CRIS) is an airborne remote-sensing system designed specifically for research on the physical, chemical, and biological characteristics of coastal waters. The CRIS includes a visible-light hyperspectral imaging subsystem for measuring the color of water, which contains information on the biota, sediment, and nutrient contents of the water. The CRIS also includes an infrared imaging subsystem, which provides information on the temperature of the water. The combination of measurements enables investigation of biological effects of both natural and artificial flows of water from land into the ocean, including diffuse and point-source flows that may contain biological and/or chemical pollutants. Temperature is an important element of such measurements because temperature contrasts can often be used to distinguish among flows from different sources: for example, a sewage outflow could manifest itself in spectral images as a local high-temperature anomaly.

  19. The RHESSI Spectrometer

    NASA Astrophysics Data System (ADS)

    Smith, D. M.; Lin, R. P.; Turin, P.; Curtis, D. W.; Primbsch, J. H.; Campbell, R. D.; Abiad, R.; Schroeder, P.; Cork, C. P.; Hull, E. L.; Landis, D. A.; Madden, N. W.; Malone, D.; Pehl, R. H.; Raudorf, T.; Sangsingkeow, P.; Boyle, R.; Banks, I. S.; Shirey, K.; Schwartz, Richard

    2002-11-01

    RHESSI observes solar photons over three orders of magnitude in energy (3 keV to 17 MeV) with a single instrument: a set of nine cryogenically cooled coaxial germanium detectors. With their extremely high energy resolution, RHESSI can resolve the line shape of every known solar gamma-ray line except the neutron capture line at 2.223 MeV. High resolution also allows clean separation of thermal and non-thermal hard X-rays and the accurate measurement of even extremely steep power-law spectra. Detector segmentation, fast signal processing, and two sets of movable attenuators allow RHESSI to make high-quality spectra and images of flares across seven orders of magnitude in intensity. Here we describe the configuration and operation of the RHESSI spectrometer, show early results on in-flight performance, and discuss the principles of spectroscopic data analysis used by the RHESSI software.

  20. Towed seabed gamma ray spectrometer

    Microsoft Academic Search

    1994-01-01

    For more than 50 years, the measurement of radioactivity has been used for onshore geological surveys and in laboratories. The British Geological Survey (BGS) has extended the use of this type of equipment to the marine environment with the development of seabed gamma ray spectrometer systems. The present seabed gamma ray spectrometer, known as the Eel, has been successfully used

  1. Ultimate sensitivity of heterodyne spectrometers

    Microsoft Academic Search

    D. Boucher; R. Bocquet; W. Chen; J. Burie

    1993-01-01

    Low noise heterodyne receivers are now used in a large variety of instruments such as radiotelescopes, far infrared laser side bands spectrometers, supersonic nozzle beams Fourier transform spectrometers, lidars or plasmas diagnostics devices. Numerous papers have been devoted to the analysis of heterodyne receivers in the attempt to reach ultimate performances. These previous papers usually retain the restrictive hypothesis of

  2. Application of terahertz spectroscopy to the characterization of biological samples using birefringence silicon grating

    NASA Astrophysics Data System (ADS)

    Saha, Shimul C.; Grant, James P.; Ma, Yong; Khalid, Ata; Hong, Feng; Cumming, David R. S.

    2012-06-01

    We present a device and method for performing vector transmission spectroscopy on biological specimens at terahertz (THz) frequencies. The device consists of artificial dielectric birefringence obtained from silicon microfluidic grating structures. The device can measure the complex dielectric function of a liquid, across a wide THz band of 2 to 5.5 THz, using a Fourier transform infrared spectrometer. Measurement data from a range of liquid specimens, including sucrose, salmon deoxyribonucleic acid (DNA), herring DNA, and bovine serum albumin protein solution in water are presented. The specimen handling is simple, using a microfluidic channel. The transmission through the device is improved significantly and thus the measurement accuracy and bandwidth are increased.

  3. Resolution capabilities of photodeposited holographic gratings

    NASA Astrophysics Data System (ADS)

    Peled, A.; Weiss, V.; Shalgi, A.; Friesem, A. A.

    1994-05-01

    Photodeposition is a light-assisted process by which thin films can be formed on substrates which are in contact with colloid solutions. The resolution capabilities of the process were experimentally investigated by holographic recording of gratings with different spatial frequencies in the range 500-2500 lines/mm. The morphology of the recorded gratings was evaluated by atomic force microscopy and by optical read-out. The diffraction efficiencies were analyzed theoretically to obtain the surface relief structure of the very thin gratings.

  4. Fiber Bragg Grating Sensors for Harsh Environments

    PubMed Central

    Mihailov, Stephen J.

    2012-01-01

    Because of their small size, passive nature, immunity to electromagnetic interference, and capability to directly measure physical parameters such as temperature and strain, fiber Bragg grating sensors have developed beyond a laboratory curiosity and are becoming a mainstream sensing technology. Recently, high temperature stable gratings based on regeneration techniques and femtosecond infrared laser processing have shown promise for use in extreme environments such as high temperature, pressure or ionizing radiation. Such gratings are ideally suited for energy production applications where there is a requirement for advanced energy system instrumentation and controls that are operable in harsh environments. This paper will present a review of some of the more recent developments. PMID:22438744

  5. Coupling gratings as waveguide functional elements

    NASA Astrophysics Data System (ADS)

    Parriaux, Olivier; Sychugov, Vladimir A.; Tishchenko, Alexander V.

    1996-07-01

    Waveguide grating couplers allow the essential function of waveguide access to be integrated together with optical processing functions on a monolithic planar substrate. Grating coupling technology is topologically and, to a large extent, technologically compatible with the planar processes which define the optical processing waveguide circuit. Poor coupling efficiency, highly dispersive character, absence of user-friendly modelling tools and fabrication difficulties have long prevented this technology from being implemented into practical sensors and microsystems. This paper makes a review of the points where decisive technological progress has been made, illustrates some useful features of waveguide coupling gratings and underlines some of the difficulties which the designer may encounter.

  6. Aplanatic and quasi-aplanatic diffraction gratings

    DOEpatents

    Hettrick, M.C.

    1987-09-14

    A reflection diffraction grating having a series of transverse minute grooves of progressively varying spacing along a concave surface enables use of such gratings for x-ray or longer wavelength imaging of objects. The variable groove spacing establishes aplanatism or substantially uniform magnetification across the optical aperture. The grating may be sued, for example, in x-ray microscopes or telescopes of the imaging type and in x-ray microprobed. Increased spatial resolution and field of view may be realized in x-ray imaging. 5 figs.

  7. Absolute Calibration of a Normal Incidence Vacuum Spectrometer Using Synchrotron Radiation

    NASA Astrophysics Data System (ADS)

    Kubo, Hirotaka; Sakasai, Akira; Nishino, Nobuhiro; Koide, Yoshihiko; Akaoka, Nobuo; Hara, Makoto; Chiba, Shinichi; Sugie, Tatsuo; Takeuchi, Hiroshi; Tanaka, Kenichiroh; Maezawa, Hideki; Yamaguchi, Naohiro

    1989-12-01

    A normal incidence spectrometer was absolutely calibrated for light 700-1250 Å in the first order and 350-650 Å in the second order using synchrotron radiation at the Photon Factory, National Laboratory for High Energy Physics. The spectrometer was equipped with a 0.4 m, 2400 grooves/mm ruled concave grating with an Al+MgF2 coating and a blaze angle of 6.9°, and a multichannel detector. Synchrotron radiation was monochromatized by a 1 m Seya-Namioka monochromator, and the absolute intensity of the incident photon flux was measured with a windowless far-UV photodiode calibrated at the National Institute of Standards and Technology, USA. The error in the sensitivity calibration was estimated to be 13-35%. The spectrometer is used to study impurity behaviors in the JT-60 tokamak.

  8. A new perspective on Mercury's surface composition and temperatures: Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS)

    NASA Astrophysics Data System (ADS)

    Arnold, Gabriele E.; Helbert, Jörn; Hiesinger, Harald; Peter, Gisbert

    2011-09-01

    MERTIS (MErcury Radiometer and Thermal Infrared Spectrometer), scheduled for launch on board the Bepi Colombo Mercury Orbiter, will be the first mid-infrared imaging spectrometer to explore the innermost planet of the Solar System from orbit. The instrument is an advanced IR technology designed to study the surface composition, and surface temperature variations of planet Mercury. High resolution and global mid-IR spectral and temperature data obtained by MERTIS will contribute to a better understanding of Mercury's genesis and evolution. MERTIS uses an uncooled microbolometer detector array. It combines a push-broom IR grating spectrometer (TIS) with a radiometer (TIR) sharing the same optics, instrument electronics, and in-fight calibration components for a wavelength range of 7-14 and 7-40 ?m, respectively. The paper summarizes the scientific objectives, observational goals, comparative laboratory spectral studies of mineral analogues, and introduces the technical overview and actual instrument development status of the experiment.

  9. Lunar orbital mass spectrometer experiment

    NASA Technical Reports Server (NTRS)

    Lord, W. P.

    1971-01-01

    The design, development, manufacture, test and calibration of five lunar orbital mass spectrometers with the four associated ground support equipment test sets are discussed. A mass spectrometer was installed in the Apollo 15 and one in the Apollo 16 Scientific Instrument Module within the Service Module. The Apollo 15 mass spectrometer was operated with collection of 38 hours of mass spectra data during lunar orbit and 50 hours of data were collected during transearth coast. The Apollo 16 mass spectrometer was operated with collection of 76 hours of mass spectra data during lunar orbit. However, the Apollo 16 mass spectrometer was ejected into lunar orbit upon malfunction of spacecraft boom system just prior to transearth insection and no transearth coast data was possible.

  10. Application of Bi Absorption Gratings in Grating-Based X-ray Phase Contrast Imaging

    NASA Astrophysics Data System (ADS)

    Lei, Yaohu; Du, Yang; Li, Ji; Huang, Jianheng; Zhao, Zhigang; Liu, Xin; Guo, Jinchuan; Niu, Hanben

    2013-11-01

    Among X-ray phase-contrast techniques, grating-based X-ray differential phase contrast (DPC) imaging using conventional X-ray tube sources is the most prominent one for widespread applications in the case of acquisition of high-quality absorption gratings in mass production. In this letter, we report on a new type of absorption grating made from Bi and manufactured by a micro-casting process. We tested Bi absorption gratings with our X-ray DPC imaging system and obtained high-quality phase-contrast images. Our efforts towards the practical application of X-ray DPC imaging are briefly outlined.

  11. Liquid crystal on subwavelength metal gratings

    NASA Astrophysics Data System (ADS)

    Palto, S. P.; Barnik, M. I.; Artemov, V. V.; Shtykov, N. M.; Geivandov, A. R.; Yudin, S. G.; Gorkunov, M. V.

    2015-06-01

    Optical and electrooptical properties of a system consisting of subwavelength metal gratings and nematic liquid crystal layer are studied. Aluminium gratings that also act as interdigitated electrodes are produced by focused ion beam lithography. It is found that a liquid crystal layer strongly influences both the resonance and light polarization properties characteristic of the gratings. Enhanced transmittance is observed not only for the TM-polarized light in the near infrared spectral range but also for the TE-polarized light in the visible range. Although the electrodes are separated by nanosized slits, and the electric field is strongly localized near the surface, a pronounced electrooptical effect is registered. The effect is explained in terms of local reorientation of liquid crystal molecules at the grating surface and propagation of the orientational deformation from the surface into the bulk of the liquid crystal layer.

  12. Electromagnetic diffraction by plane reflection diffraction gratings

    NASA Technical Reports Server (NTRS)

    Bocker, R. P.; Marathay, A. S.

    1972-01-01

    A plane wave theory was developed to study electromagnetic diffraction by plane reflection diffraction gratings of infinite extent. A computer program was written to calculate the energy distribution in the various orders of diffraction for the cases when the electric or magnetic field vectors are parallel to the grating grooves. Within the region of validity of this theory, results were in excellent agreement with those in the literature. Energy conservation checks were also made to determine the region of validity of the plane wave theory. The computer program was flexible enough to analyze any grating profile that could be described by a single value function f(x). Within the region of validity the program could be used with confidence. The computer program was used to investigate the polarization and blaze properties of the diffraction grating.

  13. Photoinduced diffraction grating in hybrid artificial molecule.

    PubMed

    Xiao, Zhi-Hong; Zheng, Li; Lin, HongZhen

    2012-01-16

    Photoinduced diffraction grating is theoretically investigated in a three-level ladder-type hybrid artificial molecule comprised of a semiconductor quantum dot (SQD) and a metal nanoparticle (MNP). The SQD and the MNP are coupled via the Coulomb interaction. The probe absorption vanishes under the action of a strong coupling field, indicating an effect of electromagnetically induced transparency (EIT). Based on this EIT effect, diffraction grating is achievable when a standing-wave coupling field is applied. It turns out that the efficiency of diffraction grating is greatly improved due to the existence of the MNP. Furthermore, the diffraction efficiency can be controlled by tuning the interaction strength between the SQD and the MNP. Nearly pure phase grating is obtained, showing high transmissivity and high diffraction efficiency up to 33%. PMID:22274466

  14. Elastomeric diffraction gratings as photothermal detectors

    E-print Network

    Prentiss, Mara

    to monitor infrared radiation, ambient pressure, and gas flow.12,13 Although the sensitivity of the elasto- scription. 2. Experiment The elastomeric gratings were fabricated by casting PDMS prepolymer Dow Corning

  15. Grating waveguide structures and their application

    NASA Astrophysics Data System (ADS)

    Friesem, Asher A.; Dudovich, Nirit; Katchalski, Tsvi; Levy-Yurista, Guy

    2002-07-01

    The research of passive and active grating waveguide structures has been ongoing in our group for the last decade. We briefly review recent research activities, emphasizing how such structures can be exploited for optical communication and for biological sensing.

  16. [Development of a micro-infrared spectrometer based on pulse infrared light source and two-double light route].

    PubMed

    Du, Xiao-qing; Wen, Zhi-yu; Xiang, Xian-yi; Long, Zai-chuan; Liu, Hai-tao; Chen, Qin

    2007-03-01

    A novel micro infrared spectrometer was designed which is different from traditional grating scanning one. This micro spectrometer introduced an uncooled infrared detector LiTaO3 with high sensitivity and small volume, and a MEMS pulsed infrared light source was adopted as emitter and chopper, which threw off traditional mechanical chopper. Combined with the design of a two-double light route, the volume of micro spectrometer was made even smaller. Primary results show that the design method of micro-infrared spectrometer is feasible, the wavelength range of instrument is wide, from 2000 to 5000 nm, and spectrum bandwidth is about 45 nm, which can be used for the sample analysis, such as plastic films, biologic liquid, environmental gas and so on. PMID:17554937

  17. Gain equalization of EDFA's with Bragg gratings

    Microsoft Academic Search

    M. Rochette; M. Guy; S. Larochelle; J. Lauzon; F. Trepanier

    1999-01-01

    Flat-gain amplifiers are needed to ensure proper amplification of every channel in wavelength-division-multiplexed communication systems. Such amplifiers can be realized by combining a precisely tailored filter with an erbium-doped fiber amplifier (EDFA). In this letter, we show that Bragg gratings can lead to accurate EDFA gain equalization. Reflection and transmission gratings have been used to demonstrate gain equalization over 32

  18. Resonant grating biosensor platform design and fabrication

    NASA Astrophysics Data System (ADS)

    Brioude, Valerie; Saoudi, Rachida; Blanc, Daniele; Reynaud, Stephanie; Tonchev, Svetlen; Lyndin, Nikolai M.; Molloy, James

    2004-02-01

    Grating coupled evanescent wave slab waveguide biosensors are now well established about twenty years after they were demonstrated. They usually rely upon mode excitation from the substrate side, providing a means to measure the bioreaction at the waveguide surface through the monitoring of the conditions of mode excitation. A new readout principle will be presented whereby the incident beam undergoes a sharp and high reflection while being trapped into the biomaterial loaded grating waveguide. The high index metal oxide waveguide and the grating are designed so that the evanescent wave sensitivity is maximum and the conditions for resonant reflection are fulfilled for both polarizations close to normal incidence. Under these conditions, the grating corrugation cannot be located on both sides of the waveguide, as usually preferred, since the grating strength of the TM polarization would be too low. The corrugation must therefore be at the analyte side of the metal oxide layer ; this calls for a specific grating fabrication technology. The option retained for low cost manufacturing is that of wet etching of Ta2O5. This is quite a challenging problem since there is no wet etchant of high density Ta2O5 which does not dissolve standard photoresist, and since the isotropy of wet etching is likely to smooth out the required short period corrugation by underetching. This paper describes the rationale of the design of the reflection interrogation scheme and brings the experimental evidence of the effect obtained on wet etched sensor platforms.

  19. Neutron range spectrometer

    DOEpatents

    Manglos, Stephen H. (East Syracuse, NY)

    1989-06-06

    A neutron range spectrometer and method for determining the neutron energy spectrum of a neutron emitting source are disclosed. Neutrons from the source are collimnated along a collimation axis and a position sensitive neutron counter is disposed in the path of the collimated neutron beam. The counter determines positions along the collimation axis of interactions between the neutrons in the neutron beam and a neutron-absorbing material in the counter. From the interaction positions, a computer analyzes the data and determines the neutron energy spectrum of the neutron beam. The counter is preferably shielded and a suitable neutron-absorbing material is He-3. The computer solves the following equation in the analysis: ##EQU1## where: N(x).DELTA.x=the number of neutron interactions measured between a position x and x+.DELTA.x, A.sub.i (E.sub.i).DELTA.E.sub.i =the number of incident neutrons with energy between E.sub.i and E.sub.i +.DELTA.E.sub.i, and C=C(E.sub.i)=N .sigma.(E.sub.i) where N=the number density of absorbing atoms in the position sensitive counter means and .sigma. (E.sub.i)=the average cross section of the absorbing interaction between E.sub.i and E.sub.i +.DELTA.E.sub.i.

  20. Elemental abundance analyses with Complejo Astronomico El Leoncito REOSC echelle spectrograms. IV. Extensions of nine previous analyses

    NASA Astrophysics Data System (ADS)

    Adelman, S. J.; Pintado, O. I.

    2000-02-01

    Using new CASLEO echelle spectrograms, we extended our elemental abundances of the sharp-lined Mercury-Manganese stars mu Lep, 14 Hya, kappa Cnc, HR 4487, HR 4817, 28 Her, and HR 7245, the closely related star 3 Cen A, and 7 Sex an A0 V star with Population I abundances, but with Population II star space motions. The lambda lambda 4500-6200 region contains a sufficient number of lines to derive high-quality abundances of these stars. For most stars, the new spectra provide additional lines for the analyses which improve their quality as well as help fill in the periodic table. Table~5 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or via http://cdsweb.u-strabg.fr/Abstract.html}

  1. Laboratory Calibration of a Field Imaging Spectrometer System

    PubMed Central

    Zhang, Lifu; Huang, Changping; Wu, Taixia; Zhang, Feizhou; Tong, Qingxi

    2011-01-01

    A new Field Imaging Spectrometer System (FISS) based on a cooling area CCD was developed. This paper describes the imaging principle, structural design, and main parameters of the FISS sensor. The FISS was spectrally calibrated with a double grating monochromator to determine the center wavelength and FWHM of each band. Calibration results showed that the spectral range of the FISS system is 437–902 nm, the number of channels is 344 and the spectral resolution of each channel is better than 5 nm. An integrating sphere was used to achieve absolute radiometric calibration of the FISS with less than 5% calibration error for each band. There are 215 channels with signal to noise ratios (SNRs) greater than 500 (62.5% of the bands). The results demonstrated that the FISS has achieved high performance that assures the feasibility of its practical use in various fields. PMID:22163746

  2. Progress of performance of MOEMS micro spectrometers through enhanced signal processing, detectors and system setup

    NASA Astrophysics Data System (ADS)

    Grüger, Heinrich; Egloff, Thomas; Messerschmidt, Matthias; Scholles, Michael

    2008-09-01

    Micro spectrometers have been realized by the use of MEMS based scanning grating chips several years ago. The main advantage is the requirement of a single detector instead of a detector array for micro spectrometers applying fixed gratings. Especially in the near infrared range beyond the detection limit of silicon detectors, this can help to reduce the system costs significantly. First measurements for test application have been performed successfully. Industrial applications require wide spectral range, high long term stability and sufficient computation power in the system itself to realize intelligent sensor heads for process monitoring and quality control. Through the recent time, many details have been improved. Extended InGaAs detectors have been used to extend the spectral range up to 2500nm. Improvements of the grating position readout improved the wavelength stability of the system even under tough operation conditions. The integration of faster digital signal processors opens the possibility to implement spectral evaluation algorithms into the system itself. Besides simple applications shown earlier like the selection of different kinds of plastic waste, now a more quantitative analysis can be achieved. For example the ethanol content of liquor samples has been measured and evaluated quantitatively.

  3. Background and Scattered Light Subtraction in the High-Resolution Echelle Modes of the Space Telescope Imaging Spectrograph

    E-print Network

    J. Christopher Howk; Kenneth R. Sembach

    1999-12-17

    We present a simple, effective approach for estimating the on-order backgrounds of spectra taken with the highest-resolution modes of the Space Telescope Imaging Spectrograph (STIS) on-board the Hubble Space Telescope. Our scheme for determining the on-order background spectrum uses polynomial fits to the inter-order scattered light visible in the two-dimensional STIS MAMA images. We present a suite of high-resolution STIS spectra to demonstrate that our background subtraction routine produces the correct overall zero point, as judged by the small residual flux levels in the centers of strongly-saturated interstellar absorption lines. Although there are multiple sources of background light in STIS echelle mode data, this simple approach works very well for wavelengths longward of Lyman-alpha. At shorter wavelengths, the smaller order separation and generally lower signal-to-noise ratios of the data can reduce the effectiveness of our background estimation procedure. Slight artifacts in the background-subtracted spectrum can be seen in some cases, particularly at wavelengths <1300 Ang. Most of these are caused by echelle scattering of strong spectral features into the inter-order light. We discuss the limitations of high-resolution STIS data in light of the uncertainties associated with our background subtraction procedure. We compare our background-subtracted STIS spectra with GHRS Ech-A observations of the DA white dwarf G191-B2B and GHRS first-order G160M observations of the early-type star HD 218915. We find no significant differences between the GHRS data and the STIS data reduced with our method in either case.

  4. Chandra Grating Observations of AGN

    E-print Network

    T. Yaqoob; U. Padmanabhan

    2002-11-15

    The highest spectral resolution data for the Fe-K lines in type I AGN, as observed with the Chandra High Energy Grating (HEG), reveal a variety of line shapes. However, the energies of the most prominent peak are all clustered tightly around 6.4 keV (weighted mean $6.403 \\pm 0.062$ keV). If all the peaks were part of single, relativistically broadened disk line, this would require unrealistically fine tuning. Thus, some of the cores must originate in distant matter (e.g. BLR, NLR, torus). On the other hand, in at least two AGN, the emission at 6.4 keV has been seen to vanish on short timescales, indicating an origin close to the central engine. For one of these (Mrk 509) this is puzzling because the HEG and simultaneous RXTE time-averaged spectra indicate only a narrow line was present at that time. Simultaneous HEG/RXTE observations for NGC 4593 indicate a broad and narrow Fe-K complex, all originating in neutral Fe, and for F9 show a narrow, neutral Fe-K component plus a broad, He-like component. The latter signature has been observed in three other AGN by XMM and may be quite common.

  5. Non-Euclidean ideal spectrometer

    E-print Network

    Earp, Henrique N Sá; Sicca, Vladmir

    2015-01-01

    We describe the mathematical scheme for an anomaly-free ideal spectrometer, based on a 2-dimensional plane medium with conical regions of bounded slope. Moreover, the construction may be realised in many different configurations.

  6. Innovative Imaging Spectrometer Calibration Techniques

    NASA Technical Reports Server (NTRS)

    Chrien, T.; Chovit, C.; Eastwood, M.

    1995-01-01

    A laboratory calibration of the Airborne Visible Infrared Imaging Spectrometer (AVIRIS) allowed experimentation with several innovative calibration techniques that would improve calibration accuracy, provide independent checks for systematic errors, and reduce the time required to collect a calibration data set.

  7. Frequency-Modulation Correlation Spectrometer

    NASA Technical Reports Server (NTRS)

    Margolis, J. S.; Martonchik, J. V.

    1985-01-01

    New type of correlation spectrometer eliminates need to shift between two cells, one empty and one containing reference gas. Electrooptical phase modulator sinusoidally shift frequencies of sample transmission spectrum.

  8. Case study of grate-chain degradation in a Grate-Kiln process

    NASA Astrophysics Data System (ADS)

    Nilsson, Erik A. A.; Pettersson, L.; Antti, M.-L.

    2013-12-01

    Austenitic stainless steels are often used in high temperature applications due to their resistance to corrosion. Grate-Kiln processes that sinter iron ore pellets use grate-chains which are made of austenitic stainless steel to withstand the severe environment. It has been shown, however, that the grate-chain is affected by several degrading mechanisms in the harsh environment of the sintering process. A grate-chain that has been in service for 8 months was investigated in order to find the mechanisms of degradation. Results show that slag products are accumulated on the grate-chain and interact with the steel as hot corrosion. The stainless steel is believed to be sensitized against inter-granular attack by carburization followed by inter-granular attack. The resistance towards degradation seems to decrease with time which is suggested to be caused by depletion of chromium.

  9. Evaluation of the ROTAX spectrometer

    Microsoft Academic Search

    H. Tietze-Jaensch; W. Schmidt; R. Geick

    1997-01-01

    After installation of the new-type rotating crystal analyser spectrometer ROTAX at ISIS, we report on practical experience and describe its current status. The rotating analyser technique works feasibly and reliably and provides an ultimate scan flexibility on a pulsed time-of-flight neutron spectrometer. The spinning analyser achieves a multiplex advantage factor of ca. 50 without compromising the resolution of the instrument.

  10. Coastal Research Imaging Spectrometer

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The Coastal Research Imaging Spectrometer (CRIS) is an airborne remote-sensing system designed specifically for research on the physical, chemical, and biological characteristics of coastal waters. The CRIS includes a visible-light hyperspectral imaging subsystem for measuring the color of water, which contains information on the biota, sediment, and nutrient contents of the water. The CRIS also includes an infrared imaging subsystem, which provides information on the temperature of the water. The combination of measurements enables investigation of biological effects of both natural and artificial flows of water from land into the ocean, including diffuse and point-source flows that may contain biological and/or chemical pollutants. Temperature is an important element of such measurements because temperature contrasts can often be used to distinguish among flows from different sources: for example, a sewage outflow could manifest itself in spectral images as a local high-temperature anomaly.anomaly. Both the visible and infrared subsystems scan in "pushbroom" mode: that is, an aircraft carrying the system moves along a ground track, the system is aimed downward, and image data are acquired in acrosstrack linear arrays of pixels. Both subsystems operate at a frame rate of 30 Hz. The infrared and visible-light optics are adjusted so that both subsystems are aimed at the same moving swath, which has across-track angular width of 15. Data from the infrared and visible imaging subsystems are stored in the same file along with aircraft-position data acquired by a Global Positioning System receiver. The combination of the three sets of data is used to construct infrared and hyperspectral maps of scanned areas shown.

  11. Encoded cell grating array in anti-counterfeit technology

    NASA Astrophysics Data System (ADS)

    Chen, Zhongyu; Bao, N. K.; Chung, Po S.

    2005-06-01

    The dot matrix hologram (DMH) has been widely used in anti-counterfeiting label. With the same technology and cell array configuration, we can encode to the incidence beam. These codes can be some image matrix grating with different grating gap and different grating orientation. When the multi-level phase diffractive grating is etched, the incidence beam on the cell appears as an encoding image. When the encoded grating and DMH are used in the same label synchronously, the technology of multi-encoded grating array enhances the anti-counterfeit ability.

  12. Grating tuned unstable resonator laser cavity

    DOEpatents

    Johnson, Larry C. (Princeton, NJ)

    1982-01-01

    An unstable resonator to be used in high power, narrow line CO.sub.2 pump lasers comprises an array of four reflectors in a ring configuration wherein spherical and planar wavefronts are separated from each other along separate optical paths and only the planar wavefronts are impinged on a plane grating for line tuning. The reflector array comprises a concave mirror for reflecting incident spherical waves as plane waves along an output axis to form an output beam. A plane grating on the output axis is oriented to reflect a portion of the output beam off axis onto a planar relay mirror spaced apart from the output axis in proximity to the concave mirror. The relay mirror reflects plane waves from the grating to impinge on a convex expanding mirror spaced apart from the output axis in proximity to the grating. The expanding mirror reflects the incident planar waves as spherical waves to illuminate the concave mirror. Tuning is provided by rotating the plane grating about an axis normal to the output axis.

  13. Discrimination of auditory gratings in birds

    PubMed Central

    Osmanski, Michael S.; Marvit, Peter; Depireux, Didier; Dooling, Robert

    2009-01-01

    Auditory gratings (also called auditory ripples) are a family of complex, broadband sounds with sinusoidally-modulated logarithmic amplitudes and a drifting spectral envelope. These stimuli have been studied both physiologically in mammals and psychophysically in humans. Auditory gratings share spectro-temporal properties with many natural sounds, including species-specific vocalizations and the formant transitions of human speech (Versnel and Shamma, 1998). We successfully trained zebra finches and budgerigars, using operant conditioning methods, to discriminate between flat-spectrum broadband noise and noises with ripple spectra of different densities that moved up or down in frequency at various rates. Results show that discrimination thresholds (minimum modulation depth) increased as a function of increasing grating periodicity and density across all species. Results also show that discrimination in the two species of birds was better at those grating densities and periodicities that are prominent in their species-specific vocalizations. Budgerigars were generally more sensitive than both zebra finches and humans. Both bird species showed greater sensitivity to descending auditory gratings, which mirrors the main direction in their vocalizations. Humans, on the other hand, showed no directional preference even though speech is somewhat downward directional. Overall, our results are suggestive of both common strategies in the processing of complex sounds between birds and mammals and specialized, species–specific variations on that processing in birds. PMID:19427374

  14. Design concept for an IR mapping spectrometer for the Pluto fast flyby mission

    NASA Technical Reports Server (NTRS)

    Fink, U.; Low, F.; Hubbard, B.; Rieke, M.; Rieke, G.; Mumma, M.; Nozette, S.; Neukum, G.; Hamel, H.; Disanti, M.

    1993-01-01

    The design of an IR mapping spectrometer that exceeds all the criteria of the Pluto Fast Flyby Mission will be presented. The instrument has a mass of approximately 1700 g and uses less than 4 W of power. The design concept is based on an f/3 spectrograph using an aberration-corrected concave holographic grating. Up to four spectral regions can be covered simultaneously by dividing the grating into two to four sections, each imaging the entrance slit on a different area of the array. The spectrography will be fed by a lightweight 5 in. f/3 telescope based on SDIO precepts. In order to provide spectroscopic access to the fundamental molecule frequencies, an extended-range NICMOS array to approximately 3.5 microns and an InSb array going to 5.8 microns will be considered.

  15. Integrated microfluidic spectroscopic sensor using arrayed waveguide grating

    NASA Astrophysics Data System (ADS)

    Hu, Zhixiong; Glidle, Andrew; Ironside, Charles N.; Sorel, Marc; Strain, Michael; Cooper, Jonathan M.; Yin, Huabing

    2013-08-01

    With non-invasive properties and high sensitivities, portable optical biosensors are extremely desirable for point-of-care (POC) applications. Lab-on-a-chip technology such as microfluidics has been treated as an ideal approach to integrate complex sample processing and analysis units with optical detection elements. The work in this paper has developed an integrated dispersive component in combination with a microfluidic chip, providing a portable and inexpensive platform for on-chip spectroscopic sensing. We demonstrate an integrated microfluidic spectroscopic sensor by using an arrayed waveguide grating (AWG) device. In particular, a visible AWG device (?c=680nm) with chip size of 12.1mm by 1.5mm was designed and fabricated by employing flamed hydrolysis deposited (FHD) silica as the waveguide material. A straight input waveguide is used to perform device characterization while a perpendicular curved waveguide is employed to introduce laser excitation light. A polymer microfluidic chip is integrated with the AWG device by oxygen plasma bonding. To prove effectiveness of the integrated spectroscopic sensor, fluorescence spectrum of an organic fluorophore (Cy5) was tested. Reconstructed spectrum by using the AWG device is compared with the outcome from a conventional spectrometer and a good consistency is presented.

  16. Measurement of diffraction gratings with a long trace profiler with application for synchrotron beamline gratings

    SciTech Connect

    Irick, S.C.; McKinney, W.R. [University of California, Lawrence Berkeley National Laboratory, Advanced Light Source, Berkeley, California94720 (United States)

    1997-07-01

    The Long Trace Profiler (LTP) is used primarily for measuring the figure of long synchrotron beamline mirrors. The LTP has also been used for measuring the figure of the substrate of beamline gratings. We propose a method for measuring the effective figure that comes from the grating groove pattern on the substrate of long beamline gratings. Analysis of grating groove patterns can be useful in determining cause of poor imaging of the diffracted light, but requires investigation of small changes of the groove frequency over the entire clear aperture of the grating. A diffraction grating that is small enough to be measured by a general purpose six inch aperture interferometer is measured by both this interferometer and the LTP, so that results for two different instruments may be compared. The height profile of the substrate light (m=0) measurement is subtracted from the height profile of the diffracted light (m=1) measurement, and the result is the effect of only the diffraction from the grooves along the entire surface. This procedure is also used for a diffraction grating that is too long to be measured by the general purpose interferometer, but is easily measured by the LTP. {copyright} {ital 1997 American Institute of Physics.}

  17. Measurement of diffraction gratings with a long trace profiler with application for synchrotron beamline gratings

    SciTech Connect

    Irick, S. C.; McKinney, W. R. [University of California, Lawrence Berkeley National Laboratory, Advanced Light Source, Berkeley, California 94720 (United States)

    1997-07-01

    The Long Trace Profiler (LTP) is used primarily for measuring the figure of long synchrotron beamline mirrors. The LTP has also been used for measuring the figure of the substrate of beamline gratings. We propose a method for measuring the effective figure that comes from the grating groove pattern on the substrate of long beamline gratings. Analysis of grating groove patterns can be useful in determining cause of poor imaging of the diffracted light, but requires investigation of small changes of the groove frequency over the entire clear aperture of the grating. A diffraction grating that is small enough to be measured by a general purpose six inch aperture interferometer is measured by both this interferometer and the LTP, so that results for two different instruments may be compared. The height profile of the substrate light (m=0) measurement is subtracted from the height profile of the diffracted light (m=1) measurement, and the result is the effect of only the diffraction from the grooves along the entire surface. This procedure is also used for a diffraction grating that is too long to be measured by the general purpose interferometer, but is easily measured by the LTP.

  18. Measurement of diffraction gratings with a long trace profiler with applications for synchrotron beamline gratings

    SciTech Connect

    Irick, S.C.; McKinney, W.R.

    1997-06-01

    The Long Trace Profiler (LTP) is used primarily for measuring the figure of long synchrotron beamline mirrors. The LTP has also been used for measuring the figure of the substrate of beamline gratings. We propose a method for measuring the effective figure that comes from the gratings groove pattern on the substrate of long beamline gratings. Analysis of gratings groove patterns can be useful in determining cause of poor imaging of the diffracted light, but requires investigation of small changes of the groove frequency over the entire clear aperture of the grating. A diffraction grating that is small enough to be measured by a general purpose six inch aperture interferometer is measured by both this interferometer and the LTP, so that results for two different instruments may be compared. The height profile of the substrate light (m = 0) measurement is subtracted from the height profile of the diffracted light (m = 1) measurement, and the result is the effect of only the diffraction f rom the grooves along the entire surface. This procedure is also used for a diffraction grating that is too long to be measured by the general purpose interferometer, but is easily measured by the LTP.

  19. Integrated optical filters using Bragg gratings and resonators

    E-print Network

    Khan, Mohammad Jalal

    2002-01-01

    This thesis provides an in-depth study of optical filters made using integrated Bragg gratings and Bragg resonators. Various topologies for making add/drop filters using integrated gratings are outlined. Each class of ...

  20. Development of Aspherical Active Gratings at NSRRC

    SciTech Connect

    Tseng, T.-C.; Wang, D.-J.; Perng, S.-Y.; Chen, C.-T.; Lin, C.-J.; Kuan, C.-K.; Ho, H.-C.; Wang, J.; Fung, H.S. [National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan (China); Chang, S.-H. [National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, Taiwan 106 (China)

    2007-01-19

    An active grating based on a novel optical concept with bendable polynomial surface profile to reduce the coma and defocus aberrations had been designed and proved by the prototype testing. Due to the low glass transition temperature of the glue and the difference of thermal expansion coefficient between the 17-4 steel bender and silicon, the prototype distorted from flat polished condition when thermally de-blocked the polishing pitch. To improve the thermal deformation of the active grating in the polishing process, a new invar bender and high curing temperature glue were adapted to glue a silicon substrate on the bender. After some tests and manufacturer polishing, it showed acceptable conditions. In this paper we will present the design and preliminary tests of the invar active grating. Meanwhile, the design and analysis of a new 17-4 PH steel bender to be electro-less nickel plating and mechanical ruling for a new beamline will also be discussed.

  1. Fiber Bragg gratings for civil engineering applications

    NASA Astrophysics Data System (ADS)

    Maher, Mohamed H.; Tabrizi, Khosrow; Prohaska, John D.; Snitzer, Elias

    1996-04-01

    Fiber Bragg gratings sensors offer a unique opportunity in civil engineering. They can be configured as a low noise distributed sensor network for measuring mechanical deformations and temperature. They are ideally suited for strain measurements of high modulus structural materials such as steel and concrete. There is considerable interest in the use of these sensors for infrastructural nondestructive testing and there have been several papers on the subject. We present some results of our experiments with fiber Bragg sensors as applied to structural engineering. These include the use of fiber gratings to measure strain behavior of steel, reinforced concrete, and some preliminary results on bituminous materials, such as asphalt concrete. In nondestructive testing using fiber Bragg gratings of structural materials the packaging of the sensors is important and is discussed.

  2. Ultra-high density diffraction grating

    DOEpatents

    Padmore, Howard A.; Voronov, Dmytro L.; Cambie, Rossana; Yashchuk, Valeriy V.; Gullikson, Eric M.

    2012-12-11

    A diffraction grating structure having ultra-high density of grooves comprises an echellette substrate having periodically repeating recessed features, and a multi-layer stack of materials disposed on the echellette substrate. The surface of the diffraction grating is planarized, such that layers of the multi-layer stack form a plurality of lines disposed on the planarized surface of the structure in a periodical fashion, wherein lines having a first property alternate with lines having a dissimilar property on the surface of the substrate. For example, in one embodiment, lines comprising high-Z and low-Z materials alternate on the planarized surface providing a structure that is suitable as a diffraction grating for EUV and soft X-rays. In some embodiments, line density of between about 10,000 lines/mm to about 100,000 lines/mm is provided.

  3. Development of Aspherical Active Gratings at NSRRC

    NASA Astrophysics Data System (ADS)

    Tseng, Tse-Chuan; Wang, Duan Jen; Perng, Shen-Yaw; Chen, Chien-Te; Lin, Chia-Jui; Kuan, Chien-Kuang; Ho, His-Chou; Wang, Jeremy; Fung, H. S.; Chang, Shuo-Hung

    2007-01-01

    An active grating based on a novel optical concept with bendable polynomial surface profile to reduce the coma and defocus aberrations had been designed and proved by the prototype testing. Due to the low glass transition temperature of the glue and the difference of thermal expansion coefficient between the 17-4 steel bender and silicon, the prototype distorted from flat polished condition when thermally de-blocked the polishing pitch. To improve the thermal deformation of the active grating in the polishing process, a new invar bender and high curing temperature glue were adapted to glue a silicon substrate on the bender. After some tests and manufacturer polishing, it showed acceptable conditions. In this paper we will present the design and preliminary tests of the invar active grating. Meanwhile, the design and analysis of a new 17-4 PH steel bender to be electro-less nickel plating and mechanical ruling for a new beamline will also be discussed.

  4. A Novel MOEMS NIR Spectrometer

    NASA Astrophysics Data System (ADS)

    Zhihai, Zhang; Xiangxia, Mo; Yuanjun, Guo; Wei, Wang

    In order to detect luminous intensity of light signal in NIR (Near-infrared) wavelength range, a novel MOEMS(Micro-Opto-Electro-Mechanical Systems) NIR spectrometer is proposed in the paper. It uses DMD (Digital Micro-mirror Device) to band filter the input spectrum. The merits of DMD are small size, low price and high scan speed. Especially, when DMD acts as a Hadamard Transform encoding mask, the SNR (signal-to-noise-ratio) can be improved by multiplexing the light intensities. The structure and the theory of this spectrometer are analyzed. The Hadamard-S matrix and mask of 63-order and 127-order are designed. The output spectrum of the new spectrometer coincides with experimental result of Shimadzu spectrometer. The resolution of the new spectrometer is 19 nm over the spectral range between 900?1700 nm while single scan time is only 2.4S. The SNR is 44.67:1. The size of optical path is 70mm × 130 mm, and it has a weight less than 1Kg. It can meet the requirement of real time measurement and portable application.

  5. Multicore optical fiber grating array fabrication for medical sensing applications

    NASA Astrophysics Data System (ADS)

    Westbrook, Paul S.; Feder, K. S.; Kremp, T.; Taunay, T. F.; Monberg, E.; Puc, G.; Ortiz, R.

    2015-03-01

    In this work we report on a fiber grating fabrication platform suitable for parallel fabrication of Bragg grating arrays over arbitrary lengths of multicore optical fiber. Our system exploits UV transparent coatings and has precision fiber translation that allows for quasi-continuous grating fabrication. Our system is capable of both uniform and chirped fiber grating array spectra that can meet the demands of medical sensors including high speed, accuracy, robustness and small form factor.

  6. The generation of group delay ripple of chirped fiber gratings

    NASA Astrophysics Data System (ADS)

    Tan, Zhongwei; Liu, Yan; Ning, Tigang; Jian, Shuisheng

    2004-01-01

    The analysis of the group delay ripple (GDR) generated by chirped fiber gratings is developed based on the Fabry-Perot (F-P) resonator. It shows clearly how the GDR is generated and why the periods of GDR varies along the chirped fiber gratings. It could also explain why apodization could suppress the GDR and how apodization affects the chirp of the grating. The theory could be used to devise the apodization of fiber gratings.

  7. Transmission grating stretcher for contrast enhancement of high power lasers.

    PubMed

    Tang, Yunxin; Hooker, Chris; Chekhlov, Oleg; Hawkes, Steve; Collier, John; Rajeev, P P

    2014-12-01

    We propose, for the first time, a transmission grating stretcher for high power lasers and demonstrate its superiority over conventional, reflective gold grating stretchers in terms of pulse temporal quality. We show that, compared to a conventional stretcher with the same stretching factor, the transmission-grating based stretcher yields more than an order of magnitude improvement in the contrast pedestal. We have also quantitatively characterized the roughness of the grating surfaces and estimated its impact on the contrast pedestal. PMID:25606870

  8. Fabrication of reflection gratings by contact copying of amplitude holographic gratings on a metal surface

    NASA Astrophysics Data System (ADS)

    Madjidi-Zolbanine, Habib; Hodjat-Zadeh, A.

    1995-04-01

    This paper describes the contact copying of amplitude transmission holographic gratings. Master gratings (MG) are written in silver halide sensitized gelatine. A smooth and flat sheet is coated with a layer of negative photoresist constituted from a combination of polyvinyl alcohol, ammonium dichromate and Arabic gum, then the MG is put in contact with the metal surface and exposed by a mercury lamp. After processing with deionized water at (35 degree(s)C), a reflection grating is obtained. For a MG with 117 l/mm of spatial frequency and 10% of diffraction efficiency (DE), we have obtained a DE of 12%.

  9. The CHANDRA HETGS X-ray Grating Spectrum of Eta Carinae

    NASA Technical Reports Server (NTRS)

    Corcoran, M. F.; Swank, J. H.; Petre, R.; Ishibashi, K.; Davidson, K.; Townsley, L.; Smith, R.; White, S.; Viotti, R.; Damineli, A.; White, Nicholas E. (Technical Monitor)

    2001-01-01

    Eta Carinae may be the most massive and luminous star in the Galaxy and is suspected to be a massive, colliding wind binary system. The CHANDRA X-ray observatory has obtained a calibrated, high-resolution X-ray spectrum of the star uncontaminated by the nearby extended soft X-ray emission. Our 89 ksec CHANDRA observation with the High Energy Transmission Grating Spectrometer (HETGS) shows that the hot gas near the star is non-isothermal. The temperature distribution may represent the emission on either side of the colliding wind bow shock, effectively 'resolving' the shock. If so, the pre-shock wind velocities are approximately 700 and 1800 km/s in our analysis, and these velocities may be interpreted as the terminal velocities of the winds from 71 Carinae and from the hidden companion star. The forbidden-to-intercombination line ratios for the He-like ions of S, Si, and Fe are large, indicating that the line forming region lies far from the stellar photosphere. The iron fluorescent line at 1.93 angstroms, first detected by ASCA, is clearly resolved from the thermal iron line in the CHANDRA grating spectrum. The Fe fluorescent line is weaker in our CHANDRA observation than in any of the ASCA spectra. The CHANDRA observation also provides the first high-time resolution lightcurve of the uncontaminated stellar X-ray emission from 77 Carinae and shows that there is no significant, coherent variability during the CHANDRA observation. The 77 Carinae CHANDRA grating spectrum is unlike recently published X-ray grating spectra of single massive stars in significant ways and is generally consistent with colliding wind emission in a massive binary.

  10. Analysis of diffraction gratings via their resonances

    NASA Astrophysics Data System (ADS)

    Vial, Benjamin; Commandré, Mireille; Zolla, Frédéric; Nicolet, André; Tisserand, Stéphane

    2011-10-01

    We analyze diffraction gratings via their resonances by a direct determination of the eigenmodes and the complex eigenfrequencies using a finite element method (FEM), that allows to study mono- or bi-periodic gratings with a maximum versatility : complex shaped patterns, with anisotropic and graded index material, under oblique incidence and arbitrary polarization. In order to validate our method, we illustrate an example of a four layer dielectric slab, and compare the results with a specific method that we have called tetrachotomy, which gives us numerically the poles of the reflection coefficient (which corresponds to the eigenfrequencies of the structure).

  11. Superfluid {sup 4}He Quantum Interference Grating

    SciTech Connect

    Sato, Yuki; Joshi, Aditya; Packard, Richard [Physics Department, University of California, Berkeley, California 94720 (United States)

    2008-08-22

    We report the first observation of quantum interference from a grating structure consisting of four weak link junctions in superfluid {sup 4}He. We find that an interference grating can be implemented successfully in a superfluid matter wave interferometer to enhance its sensitivity while trading away some of its dynamic range. We also show that this type of device can be used to measure absolute quantum mechanical phase differences. The results demonstrate the robust nature of superfluid phase coherence arising from quantum mechanics on a macroscopic scale.

  12. Near field diffraction of cylindrical convex gratings

    NASA Astrophysics Data System (ADS)

    Torcal-Milla, Francisco Jose; Sanchez-Brea, Luis Miguel; Bernabeu, Eusebio

    2015-03-01

    We analyze the field produced by a cylindrical convex diffraction grating at the Fresnel regime for several kinds of light sources, including a monochromatic quasipunctual source, finite size, and polychromatic sources. These results can help one understand the functioning of rotary optical encoder technology. A decrease in the self-image contrast is produced for finite nonpunctual sources. In addition, the polychromaticity of the source affects the smoothness of the self-images, making them quasicontinuous from a certain distance from the grating forward. Finally, we experimentally validate the obtained analytical predictions.

  13. A ballistic gravimeter with dropping holographic grating

    NASA Astrophysics Data System (ADS)

    Dmitriev, A. L.; Kotova, E. I.; Nikushchenko, E. M.; Smirnova, A. L.; Prokopenko, V. T.

    2014-11-01

    The principle of operation of a ballistic laser gravimeter based on a dropping holographic diffraction grating is described. The free-fall acceleration of the grating is determined from a change in the frequency of beats that arise during the interference of light beams diffracted on the hologram in the zeroth and first orders of diffraction. An experiment demonstrating this principle of measurement is described. The main distinctive features of the proposed gravimeter are simple design, compact size, and the possibility of using this device for analysis of high-frequency fluctuations in the gravitational-field strength.

  14. Intelligent multiparameter sensing with fiber Bragg gratings

    NASA Astrophysics Data System (ADS)

    Men, Liqiu; Lu, Ping; Chen, Qiying

    2008-08-01

    An approach to achieve intelligent sensing of multiple environmental parameters with a single-fiber sensor system is demonstrated through the use of multiplexed fiber Bragg gratings (FBGs) with coatings of different polymers and specifications. Using three FBGs of either acrylate or polyimide coating and polyimide coatings of different thicknesses, in situ discrimination of saccharinity, salinity, and temperature from the changes in the optical responses of the Bragg wavelengths of the gratings has been realized with sensitivities of 1.10×10-3 nm/%, 3.80×10-3 nm/% (blueshift), and 1.10×10-2 nm/°C (redshift), respectively.

  15. [Intercross cascaded dual-layer resonant sub-wavelength gratings].

    PubMed

    Chen, Yong-li; Zhao, Da-zun

    2009-04-01

    A security grating structure, intercross cascaded dual-layer resonant sub-wavelength grating structure, is presented. It can broaden the resonant wavelength width of resonant sub-wavelength gratings and obtain the better optical variable effect. The full-width-at half-maximum (FWHM) broadening mechanism of security grating structures is analyzed. The FWHM is dependent on the energy coupled into the grating waveguide layer. The grating structure parameters are optimized and designed. The resonance performance and grating fabrication tolerances are also studied numerically using the vector diffraction theory (the rigorous coupled wave theory). Simulation results indicate that the value of the spectral resonant peak for the security grating structure is not decreased as the incident angle increases or decreases and the maximum FWHM of different depth of grating grooves is about seven times that of the basic resonant grating structure. The resonant dual grating waveguide structure is a kind of security grating configuration with the potential to achieve higher industry application value and its resonance performance is not sensitive to manufacture errors. PMID:19626922

  16. Holographic gratings with NOA65® adhesives with edible colorant

    NASA Astrophysics Data System (ADS)

    Olivares-Pérez, A.; Fuentes-Tapia, I.; Toxqui-López, S.

    2015-03-01

    We present the preliminary results of diffraction gratings, which are made by holographic techniques with NOA65 adhesive as polymer matrix and neon purple food colors photosensitized. Gratings are recorded by diode laser ( ? = 445nm), the resulting intensity vs. exposure time curves are shown. The recorded gratings have a mixed behavior the face and the amplitude and itself-developing.

  17. Dynamic Brillouin gratings permanently sustained by chaotic lasers.

    PubMed

    Santagiustina, M; Ursini, L

    2012-03-01

    A method to induce only one permanent and localized dynamic Brillouin grating in polarization maintaining optical fibers is introduced. The generation of the grating exploits the thumbtack correlation of the chaotic laser signals. A numerical calculation, corroborated by a theoretical analysis, is performed and the grating properties, length, and reflectance determined. PMID:22378429

  18. Reflection spectrum analysis of stimulated Brillouin scattering dynamic grating

    Microsoft Academic Search

    S Nouri Jouybari; H Latifi; F Farahi

    2012-01-01

    The reflection spectrum of Brillouin dynamic grating is calculated by a numerical method called piecewise approach. A sawtooth frequency modulation is proposed to be used in Brillouin dynamic grating localization along a fiber. It is shown that the reflection spectrum has a flat band where its linewidth depends on the amplitude of frequency modulation. The maximum reflection of dynamic grating

  19. Formation mechanism and dynamics in polymer surface gratings

    Microsoft Academic Search

    T. M. Geue; M. G. Saphiannikova; O. Henneberg; U. Pietsch; P. L. Rochon; A. L. Natansohn

    2002-01-01

    We present the results of time-dependent x-ray and visible light (VIS) scattering measurements during formation of surface relief grating (SRG). These gratings are formed on polymer films containing azobenzene side groups during pulselike exposure with a holographic pattern of circularly polarized light at 488 nm. The SRG formation is accompanied by a density grating just below the film surface. Assuming

  20. Comprehensive analysis of gratings for ultraviolet space instrumentation

    NASA Technical Reports Server (NTRS)

    Mount, G. H.; Fastie, W. G.

    1978-01-01

    Comprehensive measurements in the vacuum UV range of 1200-3000 A of efficiency, polarization, and scattering of classically ruled and photoresist gratings are reported. The results show that the art of ruling gratings for vacuum UV use has reached a high level of sophistication and that careful analysis of grating properties can lead to useful improvement of the ruling art.

  1. Nanoscanning method for high-density grating measurement

    Microsoft Academic Search

    Hongxin Luo; Changhe Zhou

    2005-01-01

    The high-density grating is routinely used in a wide variety of applications using optics. However usually it is hard to measure such gratings directly by using conventional methods such as stylus profilometer and scanning probe microscope (SPM) that might damage the grating due to its fragile surface. A novel nano-scanning method based on the Talbot effect for measurement of a

  2. Evaluation of the ROTAX spectrometer

    NASA Astrophysics Data System (ADS)

    Tietze-Jaensch, H.; Schmidt, W.; Geick, R.

    1997-02-01

    After installation of the new-type rotating crystal analyser spectrometer ROTAX at ISIS, we report on practical experience and describe its current status. The rotating analyser technique works feasibly and reliably and provides an ultimate scan flexibility on a pulsed time-of-flight neutron spectrometer. The spinning analyser achieves a multiplex advantage factor of ca. 50 without compromising the resolution of the instrument. Despite these instrument merits its individual beam position at ISIS has only an unsatisfactorily weak flux, thus hindering this instrument yet to become fully competitive with other high-performance neutron spectrometers based at high-flux reactors. However, we strongly recommend a ROTAX-type instrument to be emphasized when the instrumentation suite of the future European spallation sources ESS will come under scrutiny.

  3. Mini ion trap mass spectrometer

    DOEpatents

    Dietrich, Daniel D. (Livermore, CA); Keville, Robert F. (Valley Springs, CA)

    1995-01-01

    An ion trap which operates in the regime between research ion traps which can detect ions with a mass resolution of better than 1:10.sup.9 and commercial mass spectrometers requiring 10.sup.4 ions with resolutions of a few hundred. The power consumption is kept to a minimum by the use of permanent magnets and a novel electron gun design. By Fourier analyzing the ion cyclotron resonance signals induced in the trap electrodes, a complete mass spectra in a single combined structure can be detected. An attribute of the ion trap mass spectrometer is that overall system size is drastically reduced due to combining a unique electron source and mass analyzer/detector in a single device. This enables portable low power mass spectrometers for the detection of environmental pollutants or illicit substances, as well as sensors for on board diagnostics to monitor engine performance or for active feedback in any process involving exhausting waste products.

  4. Mini ion trap mass spectrometer

    DOEpatents

    Dietrich, D.D.; Keville, R.F.

    1995-09-19

    An ion trap is described which operates in the regime between research ion traps which can detect ions with a mass resolution of better than 1:10{sup 9} and commercial mass spectrometers requiring 10{sup 4} ions with resolutions of a few hundred. The power consumption is kept to a minimum by the use of permanent magnets and a novel electron gun design. By Fourier analyzing the ion cyclotron resonance signals induced in the trap electrodes, a complete mass spectra in a single combined structure can be detected. An attribute of the ion trap mass spectrometer is that overall system size is drastically reduced due to combining a unique electron source and mass analyzer/detector in a single device. This enables portable low power mass spectrometers for the detection of environmental pollutants or illicit substances, as well as sensors for on board diagnostics to monitor engine performance or for active feedback in any process involving exhausting waste products. 10 figs.

  5. Interfacing an aspiration ion mobility spectrometer to a triple quadrupole mass spectrometer

    SciTech Connect

    Adamov, Alexey; Viidanoja, Jyrki; Kaerpaenoja, Esko; Paakkanen, Heikki; Ketola, Raimo A.; Kostiainen, Risto; Sysoev, Alexey; Kotiaho, Tapio [Laboratory of Analytical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 University of Helsinki (Finland); Division of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, FI-00014 (Finland) and Moscow Engineering Physics Institute, State University, Kashirskoe shosse 31, 115409, Moscow (Russian Federation); Laboratory of Analytical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 University of Helsinki (Finland); Environics Ltd., Graanintie 5, P.O. Box 349, FI-50101, Mikkeli (Finland); Division of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, FI-00014 University of Helsinki (Finland) and Drug Discovery and Development Technology Center, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, FI-00014 (Finland); Division of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, FI-00014 (Finland); Moscow Engineering Physics Institute, State University, Kashirskoe shosse 31, 115409, Moscow (Russian Federation); Laboratory of Analytical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 (Finland) and Division of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, FI-00014 (Finland)

    2007-04-15

    This article presents the combination of an aspiration-type ion mobility spectrometer with a mass spectrometer. The interface between the aspiration ion mobility spectrometer and the mass spectrometer was designed to allow for quick mounting of the aspiration ion mobility spectrometer onto a Sciex API-300 triple quadrupole mass spectrometer. The developed instrumentation is used for gathering fundamental information on aspiration ion mobility spectrometry. Performance of the instrument is demonstrated using 2,6-di-tert-butyl pyridine and dimethyl methylphosphonate.

  6. The GRAVITY spectrometers: thermal behaviour

    NASA Astrophysics Data System (ADS)

    Wank, Imke; Straubmeier, Christian; Wiest, Michael; Yazici, Senol; Fischer, Sebastian; Eisenhauer, Frank; Perrin, Guy S.; Perraut, Karine; Brandner, Wolfgang; Amorim, Antonio; Schöller, Markus; Eckart, Andreas

    2014-07-01

    GRAVITY is a 2nd generation VLTI Instrument o which operates on 6 interferometric baselines by using all 4 Unit Telescopes. It will deliver narrow angle astrometry with 10?as accuracy at the infrared K-band. At the 1. Physikalische Institut of the University of Cologne, which is part of the international GRAVITY consortium, two spectrometers, one for the sciene object, and one for the fringe tracking object, have been designed, manufactured and tested. These spectrometers are two individual devices, each with own housing and interfaces. For a minimized thermal background, the spectrometers are actively cooled down to an operating temperature of 80K in the ambient temperature environment of the Beam Combiner Instrument (BCI) cryostat. The outer casings are mounted thermal isolated to the base plate by glass fiber reinforced plastic (GRP) stands, copper cooling structures conduct the cold inside the spectrometers where it is routed to components via Cu cooling stripes. The spectrometers are covered with shells made of multi insulation foil. There will be shown and compared 3 cooling installations: setups in the Cologne test dewar, in the BCI dewar and in a mock-up cad model. There are some striking differences between the setup in the 2 different dewars. In the Cologne Test dewar the spectrometers are connected to the coldplate (80K); a Cu cooling structure and the thermal isolating GRP stands are bolted to the coldplate. In the BCI dewer Cu cooling structure is connected to the bottom of the nitrogen tank (80K), the GRP stands are bolted to the base plate (240K). The period of time during the cooldown process will be analyzed.

  7. FIFI LS: a field-imaging far-infrared line spectrometer for SOFIA

    NASA Astrophysics Data System (ADS)

    Geis, Norbert; Poglitsch, Albrecht; Raab, W.; Rosenthal, Dirk; Kettenring, Guenther; Beeman, Jeffrey W.

    1998-08-01

    We describe our design for an imaging far-IR spectrometer for NASA/DARA's SOFIA observatory. The design of the instrument is driven by the goal of maximizing observing efficiency. Since the sensitivity of well designed FIR instruments is limited by the thermal background of telescope and atmosphere, observing efficiency can only be increased by increasing the throughput of the spectrometer and the number of simultaneous data channels. Our instrument will feature two separate medium resolution grating spectrometers with common fore-optics feeding two large Ge:Ga arrays. The two Littrow spectrometers operate between 45-110 micrometers , and 110-210 micrometers , resp., in 1st and 2nd order. Multiplexing takes place both spectrally and spatially. An image slicer redistributes 5 by 5 pixel fields-of-view along the 1 by 25 pixel entrance slits of the spectrometers. Anamorphic collimator mirrors help keep the spectrometer compact in the cross-dispersion direction. The spectrally dispersed images of the flits are anamorphically projected onto the detector arrays, to independently match spectral and spatial resolution to detector size. We will thus be able to instantaneously cover a velocity range of approximately 1500 km/s around a selected FIR spectral line, for each of the 25 spatial pixels. For calibration and flatfielding we use blackbody calibrators internal to the instrument, at signal levels comparable to the thermal background of the telescope. An image rotator compensates field rotation during long integrations. Estimated sensitivity of the spectrometer is approximately 2 by 10(superscript -15)W/(root)Hz/pixel.

  8. Raman spectroscopy using a spatial heterodyne spectrometer: proof of concept.

    PubMed

    Gomer, Nathaniel R; Gordon, Christopher M; Lucey, Paul; Sharma, Shiv K; Carter, J Chance; Angel, S Michael

    2011-08-01

    The use of a spatial heterodyne interferometer-based spectrometer (SHS) for Raman spectroscopy is described. The motivation for this work is to develop a small, rugged, high-resolution ultraviolet (UV) Raman spectrometer that is compatible with pulsed laser sources and that is suitable for planetary space missions. UV Raman is a particular technical challenge for space applications because dispersive (grating) approaches require large spectrographs and very narrow slits to achieve the spectral resolution required to maximize the potential of Raman spectroscopy. The heterodyne approach of the SHS has only a weak coupling of resolution and throughput, so a high-resolution UV SHS can both be small and employ a wide slit to maximize throughput. The SHS measures all optical path differences in its interferogram simultaneously with a detector array, so the technique is compatible with gated detection using pulsed lasers, important to reject ambient background and mitigate fluorescence (already low in the UV) that might be encountered on a planetary surface where samples are uncontrolled. The SHS has no moving parts, and as the spectrum is heterodyned around the laser wavelength, it is particularly suitable for Raman measurements. In this preliminary report we demonstrate the ability to measure visible wavelength Raman spectra of liquid and solid materials using an SHS Raman spectrometer and a visible laser. Spectral resolution and bandpass are also discussed. Separation of anti-Stokes and Stokes Raman bands is demonstrated using two different approaches. Finally spectral bandpass doubling is demonstrated by forming an interference pattern in both directions on the ICCD detector followed by analysis using a two-dimensional Fourier transform. PMID:21819774

  9. Towed seabed gamma ray spectrometer

    SciTech Connect

    Jones, D.G. (British Geological Survey, Nottingham (United Kingdom))

    1994-08-01

    For more than 50 years, the measurement of radioactivity has been used for onshore geological surveys and in laboratories. The British Geological Survey (BGS) has extended the use of this type of equipment to the marine environment with the development of seabed gamma ray spectrometer systems. The present seabed gamma ray spectrometer, known as the Eel, has been successfully used for sediment and solid rock mapping, mineral exploration, and radioactive pollution studies. The range of applications for the system continues to expand. This paper examines the technological aspects of the Eel and some of the applications for which it has been used.

  10. Ultralow noise up-conversion detector and spectrometer at telecom band

    E-print Network

    Shentu, Guo-Liang; Wang, Xiao-Dong; Sun, Qi-Chao; Zheng, Ming-Yang; Fejer, M M; Zhang, Qiang; Pan, Jian-Wei

    2013-01-01

    We demonstrate upconversion single-photon detection for the 1550-nm band using a PPLN waveguide, long-wavelength pump, and narrowband filtering using a volume Bragg grating. We achieve total-system detection efficiency of around 30% with noise at the dark-count level of a silicon APD. Based on the new detector, a single-pixel up-conversion infrared spectrometer with a noise equivalent power of -142 dBm was demonstrated, which was better than liquid nitrogen cooled InGaAs arrary.

  11. Design and implementation of high sensitive CCD on gallium arsenide based miniaturized spectrometer

    NASA Astrophysics Data System (ADS)

    Zheng, Jiamin; Shen, Jianhua; Guo, Fangmin

    2013-08-01

    In this paper, a method on how to design and implement a miniaturized spectrometer with low-light-level (LLL) CCD on GaAs is introduced. The optical system uses a blazed grating as the dispersive element and a 1×64 CCD on GaAs as the sensor. We apply a highly integrated Cortex-M4 MCU (STM32F407), to build the data acquisition and analysis unit, providing Wi-Fi interface to communicate with the PC software. It can complete the tasks like data acquisition, digital filtering, spectral display, network communication, human-computer interaction etc.

  12. Optimization of grating duty factor in gain-coupled DFB lasers with absorptive grating-analysis and fabrication

    Microsoft Academic Search

    H. L. Cao; Y. Luo; Y. Nakano; K. Tada; M. Dobashi; H. Hosomatsu

    1992-01-01

    Grating duty factor strongly affects the performance of gain-coupled (GC) distributed feedback (DFB) laser diodes with an absorptive grating. Through numerical analysis the authors have found an optimum value in the duty factor for their low threshold operation. The minimum threshold gain achievable at this optimum duty factor is found to be almost independent of the order of the grating.

  13. The Deep Lamp Project: An Investigation of the Precision and Accuracy of the Echelle Wavelength Scales of Space Telescope Imaging Spectrograph

    NASA Astrophysics Data System (ADS)

    Ayres, Thomas R.

    2008-08-01

    The precision and absolute accuracy of the echelle mode wavelength scales of Space Telescope Imaging Spectrograph (STIS) are investigated. The method is to measure deep exposures of the onboard Pt/Cr-Ne hollow cathode calibration lamp. The standard deviation of emission spots from their laboratory wavelengths in a single image is a measure of the internal precision of the pipeline-assigned scales. The average shift of the image as a whole is a measure of the absolute accuracy. While systematic patterns can be identified in all four echelle modes (E140M, E140M, E230M, and E230H), the overall precision (even without compensating for long-range trends with ?) is excellent: of order one-tenth of the resolution element (?~600 and 300 m s-1, for medium- [M] and high- [H] resolution modes, respectively). Furthermore, the absolute accuracy and its repeatability (assessed in a time series of WAVECAL images) is of order a remarkable 100 m s-1, aside from one of the E230M modes (secondary tilt ?2269) that shows a systematic offset 10 times larger. The excellent precision of the STIS echelle wavelengths could be improved by adding higher order terms to the biquadratic polynomial currently implemented in the CALSTIS pipeline. On the other hand, the existing small distortions might be resolved more naturally by a ``physical instrument model,'' currently under development by the Space Telescope European Coordinating Facility's STIS Calibration Enhancement Project.

  14. Distributedfeedback pulse generator based on nonlinearfibre grating

    E-print Network

    Sipe,J. E.

    intensity loops transform-limited pulses, generated at 1053nm by a mode-locked, Q-switched Nd:YLF laserDistributedfeedback pulse generator based on nonlinearfibre grating B.J. Eggleton, C.M. de Sterke pulse into a pair of soliton-likeoutput pulses. This could form the basis of a distributed feedback

  15. Optical Fibre Bragg Gratings for Acoustic Sensors

    Microsoft Academic Search

    Graham Wild; Steven Hinckley

    2010-01-01

    In this paper, we give a short review of Fibre Bragg Grating (FBG) sensors for the detection of acoustic signals, in particular ultrasound. The primary advantage of FBGs as sensing elements is their spectral encoding of the measurand, which can be either strain or temperature. However, spectral decoding methods cannot be utilized to detect high frequency signals due to their

  16. X-ray objective grating spectrograph

    NASA Technical Reports Server (NTRS)

    Catura, R. C.; Stern, R. A.; Cash, W.; Windt, D. L.; Culhane, J. L.

    1988-01-01

    A grazing incidence X-ray spectrograph for investigating the spectra of cosmic X-ray sources is described. The overall instrument design is reviewed, and the key components of the spectrograph, including the gratings, telescope, and detector, are examined. Preliminary performance measurements are reported and plans for the instrument are addressed.

  17. Integrated band demultiplexer using waveguide grating routers

    Microsoft Academic Search

    C. R. Doerr; R. Pafchek; L. W. Stulz

    2003-01-01

    We present a novel band demultiplexer design for planar lightwave circuits. It consists of two perfectly sampled waveguide grating routers connected by sets of equal-path-length waveguides separated on one side. Its advantages are compactness, sharp passband corners, and a lack of chromatic dispersion.

  18. Optimize polarization-selective binary gratings

    Microsoft Academic Search

    Tien Viet Vu; Nam Kim; Dongwoo Suh; Yeungjoon Sohn; Heesook Chung; Muncheol Paek; Kwangyong Kang

    2005-01-01

    In this paper, we design a subwavelength binary grating working as a diffractive polarizing beamsplitter. The polarizing beamsplitter is then optimized by using a genetic algorithm to increase its extinction ratios up to as high as 238 and 82. We use the rigorous coupled-wave analysis method to calculate the parameters of the beamsplitter during the optimizing process.

  19. Undergraduate Experiment with Fractal Diffraction Gratings

    ERIC Educational Resources Information Center

    Monsoriu, Juan A.; Furlan, Walter D.; Pons, Amparo; Barreiro, Juan C.; Gimenez, Marcos H.

    2011-01-01

    We present a simple diffraction experiment with fractal gratings based on the triadic Cantor set. Diffraction by fractals is proposed as a motivating strategy for students of optics in the potential applications of optical processing. Fraunhofer diffraction patterns are obtained using standard equipment present in most undergraduate physics…

  20. Grating image with desired shaped dots

    Microsoft Academic Search

    Hideaki Honma; Toshiki Toda; Susumu Takahashi; Chikara Sawamura; Fujio Iwata

    2000-01-01

    A new type of Grating Image we dominate as `Sparklegram' is presented. The Sparklegram is characterized because it provides high quality and better design flexibility. These features are achieved by constructing it with shaped dots as desired. Each dot can be designed as an individual shape, for example, a star or a triangle. As dot shapes, we can use not

  1. High efficiency germanium-assisted grating coupler.

    PubMed

    Yang, Shuyu; Zhang, Yi; Baehr-Jones, Tom; Hochberg, Michael

    2014-12-15

    We propose a fiber to submicron silicon waveguide vertical coupler utilizing germanium-on-silicon gratings. The germanium is epitaxially grown on silicon in the same step for building photodetectors. Coupling efficiency based on FDTD simulation is 76% at 1.55 µm and the optical 1dB bandwidth is 40 nm. PMID:25607008

  2. Rewritable densification gratings in boron-doped fibers

    NASA Astrophysics Data System (ADS)

    Grubsky, Victor; Feinberg, Jack

    2005-06-01

    We show that the strength of long-period gratings recorded in boron-doped fibers by CO2 radiation can be significantly enhanced by a uniform pre-exposure by the same laser. The resultant gratings could be erased by a similar uniform exposure and then recorded again multiple times with no loss of fiber sensitivity. We suggest that such gratings are formed by reversible densification of the fiber core. These densification gratings have higher thermal stability than gratings written with ultraviolet light.

  3. Holographic gratings in dichromated gelatin with edible dyes

    NASA Astrophysics Data System (ADS)

    Olivares-Pérez, Arturo; Fuentes-Tapia, Israel; Jauregui-Sanchez, Yessenia; Toxqui-Lopez, Santa; Juárez-Néstor, Rosario

    2015-03-01

    We present preliminary results on diffraction gratings made with holographic techniques using dichromated gelatin (DCG) matrix with edible dyes, the purple red, Layar® and blue Sabofrut®. The gratings were recorded with a laser diode, ? = 530nm. Curves show diffracted intensity vs exposure time. The recorded gratings show different diffraction efficiencies of gratings prepared with DCG, purple red + DCG, and blue+ DCG. We observed high diffraction efficiency with purple red. All exposure conditions and reconstruction were therefor for all gratings with the same concentration of dichromate for each one of the photosensitive emulsions prepared.

  4. Reflection spectrum analysis of stimulated Brillouin scattering dynamic grating

    NASA Astrophysics Data System (ADS)

    Nouri Jouybari, S.; Latifi, H.; Farahi, F.

    2012-08-01

    The reflection spectrum of Brillouin dynamic grating is calculated by a numerical method called piecewise approach. A sawtooth frequency modulation is proposed to be used in Brillouin dynamic grating localization along a fiber. It is shown that the reflection spectrum has a flat band where its linewidth depends on the amplitude of frequency modulation. The maximum reflection of dynamic grating can be adjusted by the amplitude of modulation and the power of pump waves, which generates the grating. This grating can be useful as a fiber laser cavity mirror.

  5. Upper Limits on Metals in Quasar Lyman-Alpha Forest Clouds: Absence of C IV Lines in Echelle Spectra

    E-print Network

    D. Tytler; X. -M. Fan

    1994-01-24

    Recently Lu presented tentative evidence for C IV lines in QSO Lyman-alpha forest systems with strong lines. We have performed a similar search for C IV in our 10 km/sec echelle spectra of the bright QSO HS~1946+7658. We shifted the spectra to align the expected positions of the C IV lines in 65 Lyman-alpha systems, then added them. The resulting composite spectrum, equivalent to 390 hours of exposure time on the Lick 3-m telescope, has a signal-to-noise ratio of 80 per 0.025 Angstrom in the rest frame of the absorbers. We do not see any C IV lines down to a $2\\sigma$ limit of W$(1548) \\leq 1.4 $~m\\AA, about one-fifth of the strength of the lines seen by Lu. The C IV lines which Lu saw must be restricted to rare Lyman-alpha systems with large H I column densities $\\geq 10^{14}$~cm$^{-2}$, which are too rare to show C IV in our sample. More common Lyman-alpha systems with H I column densities of $10^{13}$ -- $10^{14}$~cm$^{-2}$ do not show C IV lines. If their ionization is H/H~I $= 10^4$ then they have [C/H] $\\leq -2.0$.

  6. Upper limits on metals in quasar Lyman-alpha forest clouds: Absence of C 5 lines in echelle spectra

    NASA Technical Reports Server (NTRS)

    Tytler, David; Fan, Xiao-Ming

    1994-01-01

    Recently Lu presented tentative evidence for C IV lines in Quasi-Stellar Object (QSO) Ly-alpha forest systems with strong lines. We have performed a similar search for C IV in our 10 km/s resolution echelle spectra of the bright QSO HS 1946+7658. We shifted the spectra to align the expected positions of the C IV lines in 65 Ly-alpha systems and then added them. The resulting composite spectrum, equivalent to 390 hr of exposure time on the Lick 3 m telescope, has a signal-to-noise ratio of 80 per 0.025 A in the rest frame of the absorbers. We do not see any C IV lines down to a 2 sigma limit of W(1548) less than or equal to 1.4 mA, about one fifth of the strength of the lines seen by Lu. The C IV lines that Lu saw must be restricted to rare Ly-alpha systems with large H I column densities greater than or equal to 10(exp 14)/sq cm, which are too rare to show C IV in our sample. More common Ly-alpha systems with H I column densities of 10(exp 13)-10(exp 14)/sq cm do not show C IV lines. If their ionization is H/H I = 10(exp 4) then they have (C/H) less than or equal to -2.0.

  7. High-resolution, high-transmission soft x-ray spectrometer for the study of biological samples

    SciTech Connect

    Fuchs, Oliver; Weinhardt, L.; Blum, M.; Weigand, M.; Umbach, E.; Bar, M.; Heske, Clemens; Denlinger, Jonathan; Chuang, Y.-D.; McKinney, Wayne; Hussain, Zahid; Gullikson, Eric; Jones, M.; Batson, Phil; Nelles, B.; Follath, R.

    2009-03-09

    We present a variable line-space grating spectrometer for soft x-rays that covers the photon energy range between 130 and 650 eV. The optical design is based on the Hettrick-Underwood principle and tailored to synchrotron-based studies of radiation-sensitive biological samples. The spectrometer is able to record the entire spectral range in one shot, i.e., without any mechanical motion, at a resolving power of 1200 or better. Despite its slitless design, such a resolving power can be achieved for a source spot as large as 30x3000 mu m2, which is important for keeping beam damage effects in radiation-sensitive samples low. The high spectrometer efficiency allows recording of comprehensive two-dimensional resonant inelastic soft x-ray scattering (RIXS) maps with good statistics within several minutes. This is exemplarily demonstrated for a RIXS map of highly oriented pyrolytic graphite, which was taken within 10 min.

  8. High-resolution, high-transmission soft x-ray spectrometer for the study of biological samples

    SciTech Connect

    Fuchs, Oliver; Weinhardt, L.; Blum, M.; Welgand, M.; Umbach, E.; Bar, M.; Heske, C.; Denlinger, J.; Chuang, Y.-D.; McKinney, W.; Hussain, Z.; Gullikson, E.; Jones, M.; Batson, P.; Nelles, B.; Follath, R.

    2009-06-11

    We present a variable line-space grating spectrometer for soft s-rays that coverst the photon energy range between 130 and 650 eV. The optical design is based on the Hettrick-Underwood principle and tailored to synchrotron-based studies of radiation-sensitive biological samples. The spectrometer is able to record the entire spectral range in one shot, i.e., without any mechanical motion, at a resolving power of 1200 or better. Despite is slitless design, such a resolving power can be achieved for a source spot as large as (30 x 3000) micrometers squared, which is important for keeping beam damage effects in radiation-sensitive samples low. The high spectrometer efficiency allows recording of comprehensive two-dimensional resonant inelastic soft x-ray scatters (RIXS) maps with good statistics within several minutes. This is exemplarily demonstrated for a RIXS map of highly oriented pyrolytic graphite, which was taken with 10 min.

  9. Compact focusing spectrometer: Visible (1 eV) to hard x-rays (200 keV)

    SciTech Connect

    Baronova, E. O.; Stepanenko, A. M. [RNC “Kurchatov Institute”, 123098 Moscow (Russian Federation); Pereira, N. R., E-mail: ninorpereira@gmail.com [Ecopulse, Inc., 7844 Vervain Ct, Springfield, Virginia 22152 (United States)

    2014-11-15

    A low-cost spectrometer that covers a wide range of photon energies can be useful to teach spectroscopy, and for simple, rapid measurements of the photon spectrum produced by small plasma devices. The spectrometer here achieves its wide range, nominally from 1 eV to 200 keV, with a series of spherically and cylindrically bent gratings or crystals that all have the same shape and the same radius of curvature; they are complemented by matching apertures and diagnostics on the Rowland circle that serves as the circular part of the spectrometer's vacuum vessel. Spectral lines are easily identified with software that finds their positions from the dispersion of each diffractive element and the known energies of the lines.

  10. The Joint astrophysical Plasmadynamic EXperiment (J-PEX): A high-resolution rocket spectrometer

    E-print Network

    M. A. Barstow; N. P. Bannister; R. G. Cruddace; M. P. Kowalski; K. S. Wood; D. J. Yentis; H. Gursky; T. W. Barbee, Jr.; W. H. Goldstein; J. F. Kordas; G. G. Fritz; J. L. Culhane; J. S. Lapingtone

    2002-09-17

    We report on the successful sounding rocket flight of the high resolution (R=3000-4000) J-PEX EUV spectrometer. J-PEX is a novel normal incidence instrument, which combines the focusing and dispersive elements of the spectrometer into a single optical element, a multilayer-coated grating. The high spectral resolution achieved has had to be matched by unprecedented high spatial resolution in the imaging microchannel plate detector used to record the data. We illustrate the performance of the complete instrument through an analysis of the 220-245A spectrum of the white dwarf G191-B2B obtained with a 300 second exposure. The high resolution allows us to detect a low-density ionized helium component along the line of sight to the star and individual absorption lines from heavier elements in the photosphere.

  11. Ultrahigh resolution soft x-ray emission spectrometer at BL07LSU in SPring-8

    SciTech Connect

    Harada, Yoshihisa [Department of Applied Chemistry, Graduate School of Engineering, University of Tokyo, Hongo, Bunkyo, Tokyo 113-8656 (Japan); Synchrotron Radiation Research Organization, University of Tokyo, Koto, Shingu-cho, Tatsuno, Hyogo 679-5165 (Japan); RIKEN/SPring-8, Sayo-cho, Sayo, Hyogo 679-5148 (Japan); CREST, Japan Science and Technology (JST), Kawaguchi, Saitama 332-0012 (Japan); Kobayashi, Masaki [Department of Applied Chemistry, Graduate School of Engineering, University of Tokyo, Hongo, Bunkyo, Tokyo 113-8656 (Japan); Synchrotron Radiation Research Organization, University of Tokyo, Koto, Shingu-cho, Tatsuno, Hyogo 679-5165 (Japan); RIKEN/SPring-8, Sayo-cho, Sayo, Hyogo 679-5148 (Japan); Niwa, Hideharu [Department of Applied Chemistry, Graduate School of Engineering, University of Tokyo, Hongo, Bunkyo, Tokyo 113-8656 (Japan); Synchrotron Radiation Research Organization, University of Tokyo, Koto, Shingu-cho, Tatsuno, Hyogo 679-5165 (Japan); Senba, Yasunori; Ohashi, Haruhiko [Japan Synchrotron Radiation Research Institute (JASRI), Koto, Sayo-cho, Sayo, Hyogo 679-5198 (Japan); Tokushima, Takashi; Horikawa, Yuka [RIKEN/SPring-8, Sayo-cho, Sayo, Hyogo 679-5148 (Japan); Shin, Shik [RIKEN/SPring-8, Sayo-cho, Sayo, Hyogo 679-5148 (Japan); CREST, Japan Science and Technology (JST), Kawaguchi, Saitama 332-0012 (Japan); Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581 (Japan); Oshima, Masaharu [Department of Applied Chemistry, Graduate School of Engineering, University of Tokyo, Hongo, Bunkyo, Tokyo 113-8656 (Japan); Synchrotron Radiation Research Organization, University of Tokyo, Koto, Shingu-cho, Tatsuno, Hyogo 679-5165 (Japan); CREST, Japan Science and Technology (JST), Kawaguchi, Saitama 332-0012 (Japan)

    2012-01-15

    An extremely high resolution flat field type slit less soft x-ray emission spectrometer has been designed and constructed for the long undulator beamline BL07LSU in SPring-8. By optimizing the ruling parameters of two cylindrical gratings, a high energy resolution {Delta}E < 100 meV and/or an E/{Delta}E{approx} 10 000 are expected for the energy range of 350 eV - 750 eV taking into account the broadening by the spatial resolution (25 {mu}m) of a CCD detector. A coma-free operation mode proposed by Strocov et al., is also applied to eliminate both defocus and coma aberrations. The spectrometer demonstrated experimentally that E/{Delta}E= 10 050 and 8046 for N 1s (402.1 eV) and Mn 2p (641.8 eV) edges, respectively.

  12. Improved Limb Atmospheric Spectrometer (ILAS) for polar stratospheric trace gas measurements

    NASA Technical Reports Server (NTRS)

    Yokota, Tatsuya; Suzuki, Makoto; Sasano, Yasuhiro; Matsuzaki, Akiyoshi; Park, Jae H.; Asada, Kazuya

    1991-01-01

    The Improved Limb Atmospheric Spectrometer (ILAS) is a grating spectrometer designed to measure vertical profiles of high latitude stratospheric constituents in a solar occultation mode. ILAS measurement gases are ozone (03), methane (CH4), nitrous oxide (N2O), nitric acid (HNO3), water vapor (H2O), nitrogen dioxide (NO2), and CFC-11 using an IR channel. Temperature, pressure, and aerosol are also measured using a visible channel. The IR channel consists of 44 detector elements which cover the spectral range 6.2 to 11.8 microns, and the visible channel is composed of 1024 pixels that cover 753 to 784 nm. ILAS will be installed on the Advanced Earth Observing Satellite (ADEOS) which will be launched in 1995. Instrument design data are outlined.

  13. Theoretical evaluation of the high-resolution vacuum ultraviolet spectrometer on SURF II.

    PubMed

    Das, N C; Madden, R P; Olson, W B; Seyoum, H M

    1992-11-01

    The high-resolution vacuum-ultraviolet spectroscopic facility at SURF II, the Synchrotron Ultraviolet Radiation Facility at the National Institute of Standards and Technology in Gaithersburg, Md., consists of a fore-optics system of three cylindrical mirrors and a 6.65-m concave grating spectrometer using the off-plane Eagle mounting. To prepare for the evaluation of the actual performance of this nationalfacility spectrometer against theoretical expectations, we computed scanning parameters, spectral resolution, and the optimum curvature and tilt of both entrance and exit slits. It is planned eventually to replace the exit slit of this instrument with a two-dimensional array detector to increase data collection efficiency. Therefore a major motivation for this work is that the results on the tilt and curvature of the exit slit can be used to maximize the resolution obtainable with the array detector through data processing. PMID:20733905

  14. New design method based on sagittal flat-field equipment of Offner type imaging spectrometer

    NASA Astrophysics Data System (ADS)

    Ji, Yiqun; Xue, Rudong; Xu, Li; Shi, Rongbao; He, Hucheng; Shen, Weimin

    2011-11-01

    Based on the wave aberration theory, a new method of optical design of the planate symmetric Offner type imaging spectrometer is performed. Astigmatism changing with the diffraction angle of the grating, the meridional and saggital focusing characters are all studied. Determination of the initial configurations and optimally design methods of two improved types of Offner imaging spectrometer are discussed in detailed. A design example with the numerical aperture larger than 0.2, and the entrance slit 30mm is given. Its spectral resolution is better than 2nm and MTF is above 0.7@20lp/mm. The smile and keystone are less than 3% and 0.2% of the pixel respectively.

  15. Spectrometer for X-ray emission experiments at FERMI free-electron-laser

    SciTech Connect

    Poletto, L., E-mail: poletto@dei.unipd.it; Frassetto, F.; Miotti, P. [CNR - Institute of Photonics and Nanotechnologies (CNR-IFN), via Trasea 7, I-35131 Padova (Italy); Di Cicco, A.; Iesari, F. [Physics Division, School of Science and Technology, Università di Camerino, I-62032 Camerino (Italy); Finetti, P. [ELETTRA - Sincrotrone Trieste, Basovizza Area Science Park, S. S. 14 - km 163,5, I-34149, Basovizza (TS) (Italy); Grazioli, C. [Department of Chemical and Pharmaceutical Sciences, University of Trieste, Via L. Giorgieri 1, I-34127 Trieste (Italy); CNR-Istituto Officina dei Materiali (CNR-IOM), Laboratorio TASC, I-34149 Trieste (Italy); Kivimäki, A. [CNR-Istituto Officina dei Materiali (CNR-IOM), Laboratorio TASC, I-34149 Trieste (Italy); Stagira, S. [Politecnico di Milano – Department of Physics, I-20133 Milano (Italy); Coreno, M. [ELETTRA - Sincrotrone Trieste, Basovizza Area Science Park, S. S. 14 - km 163,5, I-34149, Basovizza (TS) (Italy); CNR – Istituto di Struttura della Materia (CNR-ISM), UOS Basovizza, I-34149 Trieste (Italy)

    2014-10-15

    A portable and compact photon spectrometer to be used for photon in-photon out experiments, in particular x-ray emission spectroscopy, is presented. The instrument operates in the 25–800 eV energy range to cover the full emissions of the FEL1 and FEL2 stages of FERMI. The optical design consists of two interchangeable spherical varied-lined-spaced gratings and a CCD detector. Different input sections can be accommodated, with/without an entrance slit and with/without an additional relay mirror, that allow to mount the spectrometer in different end-stations and at variable distances from the target area both at synchrotron and at free-electron-laser beamlines. The characterization on the Gas Phase beamline at ELETTRA Synchrotron (Italy) is presented.

  16. An etched multilayer as a dispersive element in a curved-crystal spectrometer: implementation and performance

    E-print Network

    Jonnard, Philippe; André, Jean-Michel; Coudevylle, Jean-René; Isac, Nathalie; 10.1002/xrs.2398

    2012-01-01

    Etched multilayers obtained by forming a laminar grating pattern within interferential multilayer mirrors are used in the soft x-ray range to improve the spectral resolution of wavelength dispersive spectrometers equipped with periodic multilayers. We describe the fabrication process of such an etched multilayer dispersive element, its characterization through reflectivity measurement and simulations, and its implementation in a high-resolution Johann-type spectrometer. The specially designed patterning of a Mo/B4C multilayer is found fruitful in the range of the C K emission as the diffraction pattern narrows by a factor 4 with respect to the non-etched structure. This dispersive element with an improved spectral resolution was successfully implemented for electronic structure study with an improved spectral resolution by x-ray emission spectroscopy. As first results we present the distinction between the chemical states of carbon atoms in various compounds, such as graphite, SiC and B4C, by the different sh...

  17. MEMS-based Speckle Spectrometer

    E-print Network

    Sheinis, A I; Kuhlen, M Q

    2006-01-01

    We describe a new concept for a MEMS-based active spatial filter for astronomical spectroscopy. The goal of this device is to allow the use of a diffraction-limited spectrometer on a seeing limited observation at improved throughput over a comparable seeing-limited spectrometer, thus reducing the size and cost of the spectrometer by a factor proportional to r0/D (For the case of a 10 meter telescope this size reduction will be approximately a factor of 25 to 50). We use a fiber-based integral field unit (IFU) that incorporates an active MEMS mirror array to feed an astronomical spectrograph. A fast camera is used in parallel to sense speckle images at a spatial resolution of lambda/D and at a temporal frequency greater than that of atmospheric fluctuations. The MEMS mirror-array is used as an active shutter to feed speckle images above a preset intensity threshold to the spectrometer, thereby increasing the signal-to-noise ratio (SNR) of the spectrogram. Preliminary calculations suggests an SNR improvement of...

  18. Alpha proton x ray spectrometer

    NASA Technical Reports Server (NTRS)

    Rieder, Rudi; Waeke, H.; Economou, T.

    1994-01-01

    Mars Pathfinder will carry an alpha-proton x ray spectrometer (APX) for the determination of the elemental chemical composition of Martian rocks and soils. The instrument will measure the concentration of all major and some minor elements, including C, N, and O at levels above typically 1 percent.

  19. MEMS-based Speckle Spectrometer

    E-print Network

    A. I. Sheinis; L. Nigra; M. Q. Kuhlen

    2006-06-07

    We describe a new concept for a MEMS-based active spatial filter for astronomical spectroscopy. The goal of this device is to allow the use of a diffraction-limited spectrometer on a seeing limited observation at improved throughput over a comparable seeing-limited spectrometer, thus reducing the size and cost of the spectrometer by a factor proportional to r0/D (For the case of a 10 meter telescope this size reduction will be approximately a factor of 25 to 50). We use a fiber-based integral field unit (IFU) that incorporates an active MEMS mirror array to feed an astronomical spectrograph. A fast camera is used in parallel to sense speckle images at a spatial resolution of lambda/D and at a temporal frequency greater than that of atmospheric fluctuations. The MEMS mirror-array is used as an active shutter to feed speckle images above a preset intensity threshold to the spectrometer, thereby increasing the signal-to-noise ratio (SNR) of the spectrogram. Preliminary calculations suggests an SNR improvement of a factor of about 1.4. Computer simulations have shown an SNR improvement of 1.1, but have not yet fully explored the parameter space.

  20. Single-order diffraction grating designed by trapezoidal transmission function.

    PubMed

    Fan, Quanping; Liu, Yuwei; Wang, Chuanke; Yang, Zuhua; Wei, Lai; Zhu, Xiaoli; Xie, Changqing; Zhang, Qiangqiang; Qian, Feng; Yan, Zhuoyang; Gu, Yuqiu; Zhou, Weimin; Jiang, Gang; Cao, Leifeng

    2015-06-01

    Diffraction grating is a widely used dispersion element in spectral analysis from the infrared to the x-ray region. Traditionally, it has a square-wave transmission function, suffering from high-order diffraction contamination. Single-order diffraction can be achieved by sinusoidal amplitude transmission grating, but the fabrication is difficult. Here, we propose a novel idea to design a grating based on trapezoidal transmission function, which makes traditional grating a special case. Grating designed by this idea can not only suppress higher order diffraction by several orders of magnitude as sinusoidal amplitude grating does but also greatly reduce the fabrication difficulty to the level of processing for traditional grating. It offers a new opportunity for fabrication of grating with single-order diffraction and measurement of spectrum without contamination of high-order harmonic components. This idea can easily extend to varied-line-space grating, concave grating with single-order diffraction, or zone plates with single foci and will bring great changes in the field of grating applications. PMID:26030582

  1. Nonperiodic metallic gratings transparent for broadband terahertz waves

    NASA Astrophysics Data System (ADS)

    Ren, Xiao-Ping; Fan, Ren-Hao; Peng, Ru-Wen; Huang, Xian-Rong; Xu, Di-Hu; Zhou, Yu; Wang, Mu

    2015-01-01

    In this work, we demonstrate both theoretically and experimentally that nonperiodic metallic gratings can become transparent for broadband terahertz waves. It is shown that broadband high transmission appears in aperiodic metallic gratings (including quasiperiodic and disordered ones), which originates from the nonresonant excitations in the grating system. Quasiperiodic and disordered metallic gratings effectively weaken and even eliminate Wood's anomalies, which are the diffraction-related characters of periodic gratings. Consequently, both the transparence bandwidth and transmission efficiency are significantly increased due to the structural aperiodicity. An optimal condition is also achieved for broadband high transparency in aperiodic metallic gratings. Experimental measurements at the terahertz regime reasonably agree with both analytical analysis and numerical simulations. Furthermore, we show that for a specific light source, for example, a line source, a corresponding nonperiodic transparent grating can be also designed. We expect that our findings can be applied for transparent conducting panels, perfect white-beam polarizers, antireflective conducting solar cells, and beyond.

  2. Determination of groove spacings for concave diffraction gratings

    SciTech Connect

    Hu Zhongwen; Liu Zuping; Wang Qiuping [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029 (China)

    2004-11-01

    A long trace profiler (LTP) based method has been reported to measure the groove density of a concave grating with a curvature radius 14346.8 mm. It is appropriate for gratings with a sufficiently large curvature radius. Measurements of the groove density of a concave or convex grating with a small curvature radius could be problematic. A system based on a diffraction method and developed to check the groove variation of variable line spacing (VLS) gratings was used to measure a concave grating at NSRL recently and is the subject of this paper. For a grating with a small radius of curvature, the off-axis errors become dominant factors determining the system uncertainty. The errors are evaluated, and a correction algorithm is developed. A commercially available concave grating with a curvature radius of 750 mm was measured. The maximum relative groove density error ({delta}N/N) was 3x10{sup -5}.

  3. Tailored draw tower fiber Bragg gratings for various sensing applications

    NASA Astrophysics Data System (ADS)

    Lindner, Eric; Mörbitz, Julia; Chojetzki, Christoph; Becker, Martin; Brückner, Sven; Schuster, Kay; Rothhardt, Manfred; Willsch, Reinhardt; Bartelt, H.

    2012-02-01

    The idea of fabricating fiber Bragg gratings during the drawing process of an optical fiber dates back almost 20 years. The application of a transverse holographic writing method on a fiber draw tower offers a promising solution for a highly effective Bragg grating production. Because of the high technology requirements it took more than 10 years to develop the method into a reliable process. The improvements in the technical development during the last five years enable today a cost efficient industrial production of draw tower grating (DTG®) arrays. In this paper we report about new possibilities of the improved process with respect to the grating type (type I gratings, type II gratings), the coating type (2ORMOCER®, metals) and the fiber diameter (125?m, 80?m and below). Furthermore, we present an example for the application of draw tower fiber Bragg gratings in sensing technologies for medical applications.

  4. Sample rotating turntable kit for infrared spectrometers

    DOEpatents

    Eckels, Joel Del (Livermore, CA); Klunder, Gregory L. (Oakland, CA)

    2008-03-04

    An infrared spectrometer sample rotating turntable kit has a rotatable sample cup containing the sample. The infrared spectrometer has an infrared spectrometer probe for analyzing the sample and the rotatable sample cup is adapted to receive the infrared spectrometer probe. A reflectance standard is located in the rotatable sample cup. A sleeve is positioned proximate the sample cup and adapted to receive the probe. A rotator rotates the rotatable sample cup. A battery is connected to the rotator.

  5. Advanced Mass Spectrometers for Hydrogen Isotope Analyses

    SciTech Connect

    Chastagner, P.

    2001-08-01

    This report is a summary of the results of a joint Savannah River Laboratory (SRL) - Savannah River Plant (SRP) ''Hydrogen Isotope Mass Spectrometer Evaluation Program''. The program was undertaken to evaluate two prototype hydrogen isotope mass spectrometers and obtain sufficient data to permit SRP personnel to specify the mass spectrometers to replace obsolete instruments.

  6. Advanced Mass Spectrometers for Hydrogen Isotope Analyses

    Microsoft Academic Search

    Chastagner

    2001-01-01

    This report is a summary of the results of a joint Savannah River Laboratory (SRL) - Savannah River Plant (SRP) ''Hydrogen Isotope Mass Spectrometer Evaluation Program''. The program was undertaken to evaluate two prototype hydrogen isotope mass spectrometers and obtain sufficient data to permit SRP personnel to specify the mass spectrometers to replace obsolete instruments.

  7. A phase-sensitive superheterodyne ultrasonic spectrometer

    Microsoft Academic Search

    S. Banerjee; M. K. Gunasekaran; A. K. Raychaudhuri

    1990-01-01

    The authors present the design and fabrication details of a phase-sensitive radio-frequency superheterodyne ultrasonic spectrometer. They also present results of measurements to test the operation of the spectrometer. The spectrometer allows simultaneous measurements of both velocity and attenuation over a wide frequency range with little adjustment. It has been built mainly using commonly available RF circuit components.

  8. Moderate Resolution Imaging Spectrometer-Tilt (MODIS-T) baseline concept

    NASA Technical Reports Server (NTRS)

    Magner, Thomas J.

    1991-01-01

    There will be several state of the art spectrometers in operation on the NASA Polar Orbiting Platform (NPOP-1) as part of the Earth Observing System (EOS). The Moderate Resolution Imaging Spectrometer (MODIS) will consist of two imaging spectroradiometric instruments, one nadir viewing (MODIS-N) and the other tiltable (MODIS-T) for ocean observation and land bidirectional reflectance studies. The Moderate Resolution Imaging Spectrometer-Tilt (MODIS-T) instrument is presently being constructed for flight on the EOS. It is an imaging spectrometer utilizing a grating type, reflecting Schmidt optical design that must provide a 1.1 kilometer spatial resolution at nadir from a spacecraft altitude of 705 kilometers with a 1500 kilometer cross-track swath and a +/- 50 degree forward and aft tilt capability. The instrument is required to cover the wavelength range from 400 to 880 nanometers in approximately 15 nanometer steps with less than 2.3 percent instrument induced polarization. The absolute radiometric accuracy must be at least 5 percent over the full dynamic range of the instrument.

  9. Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) spectrometer design and performance

    NASA Technical Reports Server (NTRS)

    Macenka, Steven A.; Chrisp, Michael P.

    1987-01-01

    The development of the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) has been completed at JPL. This paper outlines the functional requirements of the spectrometer optics subsystem, and describes the spectrometer optical design. The optical subsystem performance is shown in terms of spectral modulation transfer functions, radial energy distributions, and system transmission at selected wavelengths for the four spectrometers. An outline of the spectrometer alignment is included.

  10. The Hyperspectral Thermal Emission Spectrometer (HyTES): Preliminary Results

    NASA Technical Reports Server (NTRS)

    Hook, Simon; Johnson, William R.; Eng, Bjorn T.; Gunapala, Sarah D.; Lamborn, Andrew U.; Mouroulis, Pantazis, Z.; Mouroulis, Pantazis, Z.; Paine, Christopher G.; Soibel, Alexander; Wilson, Daniel W.

    2011-01-01

    The Hyperspectral Thermal Emission Spectrometer (HyTES) is being developed as part of the risk reduction activities associated with the Hyperspectral Infrared Imager (HyspIRI). HyspIRI is one of the Tier 2 Decadal Survey Missions. HyTES will provide information on how to place the filters on the HyspIRI Thermal Infrared Instrument (TIR) as well as provide antecedent science data. The pushbroom design has 512 spatial pixels over a 50-degree field of view and 256 spectral channels between 7.5 micrometers to 12 micrometers. HyTES includes many key enabling state-of-the-art technologies including a high performance convex diffraction grating, a quantum well infrared photodetector (QWIP) focal plane array, and a compact Dyson-inspired optical design. The Dyson optical design allows for a very compact and optically fast system (F/1.6). It also minimizes cooling requirements due to the fact it has a single monolithic prism-like grating design which allows baffling for stray light suppression. The monolithic configuration eases mechanical tolerancing requirements which are a concern since the complete optical assembly is operated at cryogenic temperatures ((is) approximately 100K). The QWIP allows for optimum spatial and spectral uniformity and provides adequate responsivity or D-star to allow 200mK noise equivalent temperature difference (NEDT) operation across the LWIR passband. Assembly of the system is nearly complete. After completion, alignment results will be presented which show low keystone and smile distortion. This is required to minimize spatial-spectral mixing between adjacent spectral channels and spatial positions. Predictions show the system will have adequate signal to noise for laboratory calibration targets.

  11. Atomic resonance spectrometers and filters (review)

    SciTech Connect

    Matveev, O.I.

    1987-09-01

    The authors review the physical principles of recording and filtering light quanta with the aid of atomic resonance media and assess the latest accomplishments and future applications of atomic resonance spectrometers and filters in various fields. Specific topics include fluorescence resonance spectrometers and their performance in absorption and emission spectroscopy;fluorescence resonance spectrometers working with excited atoms; resonance absorption filters; optoacoustic resonance spectrometers; magneto-optical filters; ionization resonance spectrometers using lasers; frequency standards for laser radiation and the detection of infrared and ultrahigh-frequency radiation.

  12. Novel imaging spectrometers and polarimeters

    NASA Astrophysics Data System (ADS)

    Dereniak, Eustace L.

    2013-12-01

    The use of two dimensional arrays has enabled the development of novel imaging spectrometers and polarimeters with snapshot capabilities, meaning the entire data cube can be recorded simultaneously. This presentation will discuss the development of spectrometer and polarimeter imagers that use new optical designs based on old ideas. The presentation contains an overview of the various types of imaging sensors that have been developed at the Optical Detection Lab of the University of Arizona. The goal of our research is to develop instruments capable of discriminating objects in biological tissue and within the human eye. Additionally, instruments of this type will be capable of spectrally monitoring simultaneously chemical or biological processes in real time in four dimensions (x,y,?,t).

  13. Binocular vision measurement using Dammann grating.

    PubMed

    Wei, Shengbin; Wang, Shaoqing; Zhou, Changhe; Liu, Kun; Fan, Xin

    2015-04-10

    In this paper, we propose a novel three-dimensional (3D) profilometry using a binocular camera and a 64?×?64 Dammann grating for generation of a regular square laser array. A new constraint called a "ray constraint," taking advantage of the splitting characteristic of Dammann grating, is proposed for binocular matching. Binocular matching is realized by using ray constraint and precalibration of a laser array. Point clouds without outliers are obtained with binocular matching results according to triangulation. The experimental apparatus weighs less than 170 g with a width of less than 14 cm. We used this apparatus to scan a statue of Apollo under indoor illumination (at 450 lux). Its 3D model with complex profile was reconstructed by more than 150,000 points. This 3D profilometry has advantages of low cost, low power, and small size and should be useful for practical applications. PMID:25967310

  14. Electron interferometry with nano-fabricated gratings

    NASA Astrophysics Data System (ADS)

    Batelaan, Herman; Gronniger, Glen; Barwick, Brett; Gilbert, Stephanie

    2006-05-01

    We have realized a three grating electron interferometer. We used free standing, metal-coated gratings with a 100 nm periodicity. Fringes are observed at 10, 8, 6, and 4 keV. Our best observed contrast is about 20 percent. This contrast exceeds our calculated maximum contrast for a Moire deflectometer by a factor of 4 and shows the quantum mechanical nature of this device. Our path integral calculation predicts a maximum contrast of about 40 percent for our experimental configuration. Our contrast does not exceed this value and is possibly limited by interferometer alignment. Our results also confirm our earlier prediction that neither image charge interaction, nor dephasing or decoherence effects prevent the construction of this electron interferometer.

  15. Grating Light Valve: revolutionizing display technology

    NASA Astrophysics Data System (ADS)

    Bloom, David M.

    1997-05-01

    The grating light valve (GLV) technology is a micromechanical phase grating. By providing controlled diffraction of incident light, a GLV device will produce bright or dark pixels in a display system. With pulse width modulation, a GLV device will produce precise gray-scale or color variations. Built using micro electromechanical system technology, and designed to be manufactured using mainstream IC fabrication technology, the GLV device can be made both small and inexpensively. A variety of display systems can be built using GLV technology each benefiting form the high contrast ratio, fill ratio, and brightness of this technology. In addition, GLV technology can provide high resolution, low power consumption, and digital gray-scale and color reproduction.

  16. Fluidized bed boiler having a segmented grate

    DOEpatents

    Waryasz, Richard E. (Longmeadow, MA)

    1984-01-01

    A fluidized bed furnace (10) is provided having a perforate grate (9) within a housing which supports a bed of particulate material including some combustibles. The grate is divided into a plurality of segments (E2-E6, SH1-SH5, RH1-RH5), with the airflow to each segment being independently controlled. Some of the segments have evaporating surface imbedded in the particulate material above them, while other segments are below superheater surface or reheater surface. Some of the segments (E1, E7) have no surface above them, and there are ignitor combustors (32, 34) directed to fire into the segments, for fast startup of the furnace without causing damage to any heating surface.

  17. Grazing-angle scattering of electromagnetic waves in gratings with varying mean parameters: grating eigenmodes

    NASA Astrophysics Data System (ADS)

    Gramotnev, D. K.; Goodman, S. J.; Nieminen, T. A.

    2004-03-01

    A highly unusual pattern of strong multiple resonances for bulk electromagnetic waves is predicted and analysed numerically in thick periodic holographic gratings in a slab with the mean permittivity that is larger than that of the surrounding media. This pattern is shown to exist in the geometry of grazing-angle scattering (GAS), that is when the scattered wave (+1 diffracted order) in the slab propagates almost parallel to the slab (grating) boundaries. The predicted resonances are demonstrated to be unrelated to resonant generation of the conventional guided modes of the slab. Their physical explanation is associated with resonant generation of a completely new type of eigenmodes in a thick slab with a periodic grating. These new slab eigenmodes are generically related to the grating; they do not exist if the grating amplitude is zero. The field structure of these eigenmodes and their dependence on structural and wave parameters is analysed. The results are extended to the case of GAS of guided modes in a slab with a periodic groove array of small corrugation amplitude and small variations in the mean thickness of the slab at the array boundaries.

  18. Miniature Grating for Spectrally-Encoded Endoscopy

    PubMed Central

    Kang, Dongkyun; Martinez, Ramses V.; Whitesides, George M.

    2013-01-01

    Spectrally-encoded endoscopy (SEE) is an ultraminiature endoscopy technology that acquires high-definition images of internal organs through a sub-mm endoscopic probe. In SEE, a grating at the tip of the imaging optics diffracts the broadband light into multiple beams, where each beam with a distinctive wavelength is illuminated on a unique transverse location of the tissue. By encoding one transverse coordinate with the wavelength, SEE can image a line of the tissue at a time without using any beam scanning devices. This feature of the SEE technology allows the SEE probe to be miniaturized to sub-mm dimensions. While previous studies have shown that SEE has the potential to be utilized for various clinical imaging applications, the translation of SEE for medicine has been hampered by challenges in fabricating the miniature grating inherent to SEE probes. This paper describes a new fabrication method for SEE probes. The new method uses a soft lithographic approach to pattern a high-aspect-ratio grating at the tip of the miniature imaging optics. Using this technique, we have constructed a 500-?m-diameter SEE probe. The miniature grating at the tip of the probe had a measured diffraction efficiency of 75%. The new SEE probe was used to image a human finger and formalin fixed mouse embryos, demonstrating the capability of this device to visualize key anatomic features of tissues with high image contrast. In addition to providing high quality imaging SEE optics, the soft lithography method allows cost-effective and reliable fabrication of these miniature endoscopes, which will facilitate the clinical translation of SEE technology. PMID:23503940

  19. Microwave photonics based on fiber Bragg gratings

    Microsoft Academic Search

    J. Mora; J. L. Cruz; A. Diez; M. V. Andres; B. Ortega; D. Pastor; S. Sales; J. Capmany

    2003-01-01

    Microwave and mm-wave photonics for broadband communications is an area of important growth and of great interest for information society technologies (Internet traffic, video on demand, >1 Gb\\/s to the home, 40 Gb\\/s optical systems, optical beam forming for intelligent antennas, all-optical networks, etc.). Fiber Bragg gratings are key components for the development of low-cost microwave photonics. Reliability and high

  20. Apodized Silicon-on-Insulator Bragg Gratings

    Microsoft Academic Search

    Alexandre D. Simard; Nezih Belhadj; Yves Painchaud; Sophie LaRochelle

    2012-01-01

    An accurate control of the apodization profile is still an issue for integrated Bragg grating filters fabricated in silicon-on-insulator because of the high modal confinement of these waveguides. In this letter, we present two fabrication-friendly apodization techniques that are compatible with deep UV lithography and can be used in mass-production of photonic-integrated circuits. These techniques are reliable even for weak

  1. A novel fibre Bragg grating hydrophone system

    NASA Astrophysics Data System (ADS)

    Wang, Yanhua; Ren, Wenhua; Tan, Zhongwei; Liu, Yan; Jian, Shuisheng; Gong, Taorong

    2007-11-01

    A novel fibre Bragg grating (FBG) hydrophone system is introduced in the paper. The influence of the sound pressure on the FBG is transformed to light intensity measurement with tuned laser. Elastic material and matched FBGs are employed to enhance the sensitivity of the hydrophone system. The hydrophone system can operate in a wide acoustic frequency range from 100Hz to 3kHz and good linear relationship is observed between the output light intensity and the sound pressure.

  2. A three-grating electron interferometer

    NASA Astrophysics Data System (ADS)

    Gronniger, G.; Barwick, B.; Batelaan, H.

    2006-10-01

    We report the observation of fringes from a three-grating electron interferometer. Interference fringes have been observed at low energies ranging from 6 to 10 keV. Contrasts of up to 25% are recorded and exceed the maximal contrast of the classical equivalent Moiré deflectometer. This type of interferometer could serve as a separate beam Mach Zehnder interferometer for low-energy electron interferometry experiments.

  3. Fiber Bragg grating-based acceleration sensor

    Microsoft Academic Search

    Mathias S. Muller; Thorbjom C. Buck; Alexander W. Koch

    2009-01-01

    We present the design process of a fiber Bragg grating based fiber-optic single-axis acceleration sensor with minimized crosstalk. Crosscoupling of non-directional accelerations is minimized by introducing a unique double-membrane fixture of the sensor's mass of inertia leading to an almost diagonal form of the sensors stiffness-matrix. The sensor's resonance frequency, the sensor's sensitivity towards the stiffness of the spring-mass system

  4. Spectrometers for Beta Decay Electrons

    NASA Astrophysics Data System (ADS)

    Jiang, Yong; Hirshfield, Jay

    2015-04-01

    Inspired by the neutrino mass direct measurement experiment Project 8, precision spectrometers are proposed to simultaneously measure energy and momentum of beta-decay electrons produced in rare nuclear events with improved energy resolution. For detecting single beta decay electrons near the end-point from a gaseous source such as tritium, one type of spectrometer is proposed to utilize stimulated cyclotron resonance interaction of microwaves with electrons in a waveguide immersed in a magnetic mirror. In the external RF fields, on-resonance electrons will satisfy both the cyclotron resonance condition and waveguide dispersion relationship. By correlating the resonances at two waveguide modes, one can associate the frequencies with both the energy and longitudinal momentum of an on-resonance electron to account for the Doppler shifts. For detecting neutrino-less double-beta decay, another spectrometer is proposed with thin foil of double-beta-allowed material immersed in a magnetic field, and RF antenna array for detection of synchrotron radiation from electrons. It utilizes the correlation between the antenna signals including higher harmonics of radiation to reconstruct the total energy distribution.

  5. Khayyam: a second generation tunable spatial heterodyne spectrometer for broadband observation of diffuse emission line targets

    NASA Astrophysics Data System (ADS)

    Hosseini, Sona; Harris, Walter

    2011-09-01

    We report on progress toward development of a second-generation tunable spatial heterodyne spectrometer (TSHS) at the fixed focus of the Coudé Auxiliary Telescope (CAT) in the Shane observatory at Lick Observatory (Khayyam). SHS instruments are a class of interferometric sensor capable of providing a combination of large étendue, high resolving power (R=?/d?~ 105) and wide field of view (FOV~0.5 degree) at Optical and NUV wavelengths in a compact format. The TSHS implementation addresses the bandpass limitation of the basic SHS through controlled rotation of pilot mirrors in the interferometer. The use of a single grating as both a dispersing and beam-splitting element in the all-reflective SHS greatly relaxes the precision required in the alignment of the other optical elements relative to a more typical scanning Fourier Transform Spectrometer and allows the TSHS implementation to be accomplished with low-cost commercial rotation stages. The new design builds on a previous design originally tested in 2007, and will address several issues identified with the input beam, output imaging, and grating efficiency (Dawson and Harris, 2009). Here we will discuss the design considerations going into this new system and the initial results of the installation and testing of the TSHS and the future plans.

  6. Analysis of fiber Bragg gratings for dispersion compensation in reflective and transmissive geometries

    Microsoft Academic Search

    Natalia M. Litchinitser; David B. Patterson

    1997-01-01

    Numerical analysis of the dispersion-compensating properties of fiber Bragg gratings (FBGs) in both reflective and transmissive modes is presented. First, the sensitivity of chirped, reflective gratings to the grating chirp parameter, index modulation, and grating length is examined, showing that apodization provides lower sensitivity to variations in these parameters. Second, we introduce a new transmissive geometry for grating-based dispersion compensation

  7. An undulator-based spherical grating monochromator beamline for angle-resolved photoemission spectroscopy

    NASA Astrophysics Data System (ADS)

    Hoffmann, S. V.; Søndergaard, Ch.; Schultz, Ch.; Li, Z.; Hofmann, Ph.

    2004-05-01

    A new spherical grating undulator beamline has been commissioned at the synchrotron radiation source ASTRID in Aarhus. It covers an energy range from 12 to 130 eV with a resolving power of about 15.000. This beamline is combined with an end-station for angle-resolved photoemission. The spectrometer is a 75 mm mean radius hemispherical electron energy analyzer which is mounted on a goniometer within the ultra-high vacuum chamber. The motions of the analyzer and several settings of the beamline are motorized and computerized scans can be performed. The system is in particular well suited for measurements of the electronic structure along arbitrary lines in k?||-space, Fermi surface mapping and studying the polarization dependence of photoemission features.

  8. Adaptation of UVSOR-Type Plane-Grating Monochromator in Saga

    SciTech Connect

    Sugiyama, H.; Takahashi, K.; Ogawa, K.; Azuma, J.; Kamada, M. [Synchrotron Light Application Center, Saga University, Saga 840-8502 (Japan)

    2010-06-23

    The plane grating monochromator (PGM) is one of the most useful monochromators in the world. The design concept of the PGM originates from the characteristics of synchrotron radiation itself, namely parallel rays and small source size. Since the performance of the PGM depends on the beam emittance of the storage ring, it is expected that even the used PGM may be utilized in recent facility. Therefore, the UVSOR-type PGM that had been used for more than twenty years in UVSOR was adapted to the university's branch beamline in Saga-LS with several modifications. The performance tests were carried out with a photoelectron spectrometer, and the observed values were compared with the ray-tracing calculation. The results show that the adaptation of the UVSOR-type PGM is good enough to study new functional materials.

  9. Whispering gallery mode resonators augmented with engraved diffraction gratings.

    PubMed

    Aveline, David C; Baumgartel, Lukas M; Lin, Guoping; Yu, Nan

    2013-02-01

    We report the demonstration of whispering gallery mode (WGM) resonators augmented with diffraction gratings. We apply focused ion beam (FIB) methods to precisely engrave a surface grating directly into the perimeter of a crystalline disc. The grating provides a simple and highly directional free-space coupling mechanism with superior stability to evanescent coupling techniques. These integrated gratings can also provide control of the resonance spectrum, significantly reducing the mode density. Our FIB fabrication process does not introduce significant loss; Q?3×10(7) has been demonstrated. The wavelength dependence of the diffraction angle was found to be in excellent agreement with grating theory. The versatility of spectral control and far-field grating coupling will have significant impact in WGM resonator applications in lasers, sensors, and optoelectronics. PMID:23381412

  10. Tiled-grating compression of multiterawatt laser pulses.

    PubMed

    Cotel, Arnaud; Crotti, Caroline; Audebert, Patrick; Le Bris, Catherine; Le Blanc, Catherine

    2007-06-15

    High-energy petawatt lasers require large diffraction gratings for pulse compression. As an alternative to meter-sized gratings, we demonstrate the capability of a tiled-grating system to compress multiterawatt subpicosecond laser pulses. Using a 100 TW-class Nd:glass chirped-pulse amplification laser facility, we report on the performance of a two-grating mosaic to compress high-energy pulses to 2.5 J, 450 fs (5.5 TW) in air with a beam size of 50 mm and energy transmission of 63%. Stability of the grating mosaic alignment was realized by use of an accurate nanopositioning optomechanical system. The output Gaussian spectrum was preserved from grating-gap spectral clipping and was free of modulation. PMID:17572768

  11. Design and applications of silicon waveguide grating couplers

    NASA Astrophysics Data System (ADS)

    Chen, Xia; Cheng, Zhenzhou; Fung, Christy K. Y.; Tsang, Hon K.

    2012-01-01

    We review our recent work on waveguide grating couplers, including an apodized grating coupler with engineered coupling strength to achieve Gaussian-like output profile, which greatly improves the fiber-chip coupling efficiency. We will also discuss a new class of grating couplers involving the use of sub-wavelength nanostructures to engineer the optical properties. Effective medium theory can be used in the design of sub-wavelength structures, which, when properly engineered, can offer broadband coupling and polarization independence. Other applications of waveguide gratings, for example bi-wavelength two dimensional gratings coupler for (de-)multiplexing two different wavelengths, fiber-waveguide hybrid lasers and mid-infrared grating couplers on silicon-on-sapphire wafer will also be briefly discussed.

  12. Grazing incidence extreme ultraviolet spectrometer fielded with time resolution in a hostile z-pinch environment.

    PubMed

    Williamson, K M; Kantsyrev, V L; Safronova, A S; Wilcox, P G; Cline, W; Batie, S; LeGalloudec, B; Nalajala, V; Astanovitsky, A

    2011-09-01

    This recently developed diagnostic was designed to allow for time-gated spectroscopic study of the EUV radiation (4 nm < ? < 15 nm) present during harsh wire array z-pinch implosions. The spectrometer utilizes a 25 ?m slit, an array of 3 spherical blazed gratings at grazing incidence, and a microchannel plate (MCP) detector placed in an off-Rowland position. Each grating is positioned such that its diffracted radiation is cast over two of the six total independently timed frames of the MCP. The off-Rowland configuration allows for a much greater spectral density on the imaging plate but only focuses at one wavelength per grating. The focal wavelengths are chosen for their diagnostic significance. Testing was conducted at the Zebra pulsed-power generator (1 MA, 100 ns risetime) at the University of Nevada, Reno on a series of wire array z-pinch loads. Within this harsh z-pinch environment, radiation yields routinely exceed 20 kJ in the EUV and soft x-ray. There are also strong mechanical shocks, high velocity debris, sudden vacuum changes during operation, energic ion beams, and hard x-ray radiation in excess of 50 keV. The spectra obtained from the precursor plasma of an Al double planar wire array contained lines of Al IX and AlX ions indicating a temperature near 60 eV during precursor formation. Detailed results will be presented showing the fielding specifications and the techniques used to extract important plasma parameters using this spectrometer. PMID:21974586

  13. Ion mobility spectrometer / mass spectrometer (IMS-MS).

    SciTech Connect

    Hunka Deborah Elaine; Austin, Daniel E.

    2005-07-01

    The use of Ion Mobility Spectrometry (IMS) in the Detection of Contraband Sandia researchers use ion mobility spectrometers for trace chemical detection and analysis in a variety of projects and applications. Products developed in recent years based on IMS-technology include explosives detection personnel portals, the Material Area Access (MAA) checkpoint of the future, an explosives detection vehicle portal, hand-held detection systems such as the Hound and Hound II (all 6400), micro-IMS sensors (1700), ordnance detection (2500), and Fourier Transform IMS technology (8700). The emphasis to date has been on explosives detection, but the detection of chemical agents has also been pursued (8100 and 6400). Combining Ion Mobility Spectrometry (IMS) with Mass Spectrometry (MS) is described. The IMS-MS combination overcomes several limitations present in simple IMS systems. Ion mobility alone is insufficient to identify an unknown chemical agent. Collision cross section, upon which mobility is based, is not sufficiently unique or predictable a priori to be able to make a confident peak assignment unless the compounds present are already identified. Molecular mass, on the other hand, is much more readily interpreted and related to compounds. For a given compound, the molecular mass can be determined using a pocket calculator (or in one's head) while a reasonable value of the cross-section might require hours of computation time. Thus a mass spectrum provides chemical specificity and identity not accessible in the mobility spectrum alone. In addition, several advanced mass spectrometric methods, such as tandem MS, have been extensively developed for the purpose of molecular identification. With an appropriate mass spectrometer connected to an ion mobility spectrometer, these advanced identification methods become available, providing greater characterization capability.

  14. Ion Mobility Spectrometer / Mass Spectrometer (IMS-MS).

    SciTech Connect

    Hunka, Deborah E; Austin, Daniel

    2005-10-01

    The use of Ion Mobility Spectrometry (IMS)in the Detection of Contraband Sandia researchers use ion mobility spectrometers for trace chemical detection and analysis in a variety of projects and applications. Products developed in recent years based on IMS-technology include explosives detection personnel portals, the Material Area Access (MAA) checkpoint of the future, an explosives detection vehicle portal, hand-held detection systems such as the Hound and Hound II (all 6400), micro-IMS sensors (1700), ordnance detection (2500), and Fourier Transform IMS technology (8700). The emphasis to date has been on explosives detection, but the detection of chemical agents has also been pursued (8100 and 6400).Combining Ion Mobility Spectrometry (IMS) with Mass Spectrometry (MS)The IMS-MS combination overcomes several limitations present in simple IMS systems. Ion mobility alone is insufficient to identify an unknown chemical agent. Collision cross section, upon which mobility is based, is not sufficiently unique or predictable a priori to be able to make a confident peak assignment unless the compounds present are already identified. Molecular mass, on the other hand, is much more readily interpreted and related to compounds. For a given compound, the molecular mass can be determined using a pocket calculator (or in one's head) while a reasonable value of the cross-section might require hours of computation time. Thus a mass spectrum provides chemical specificity and identity not accessible in the mobility spectrum alone. In addition, several advanced mass spectrometric methods, such as tandem MS, have been extensively developed for the purpose of molecular identification. With an appropriate mass spectrometer connected to an ion mobility spectrometer, these advanced identification methods become available, providing greater characterization capability.3 AcronymsIMSion mobility spectrometryMAAMaterial Access AreaMSmass spectrometryoaTOForthogonal acceleration time-of-flightTOFtime-of-flight4

  15. A tunable inverse-hemisphere-shaped Bragg grating sensor

    NASA Astrophysics Data System (ADS)

    Ryu, Yunha; Kim, Kyoungsik

    2013-09-01

    In this work, we investigated the diffraction of inverse-hemisphere shaped polymer grating. We fabricated an inverse-hemisphere- shaped grating structure using soft lithography of close-packed PS nanospheres that is easy and cost-effective method. Then the diffraction wavelength shift induced from lattice change was measured. The periodicity of the grating was tuned by swelling in acetone. The measurement results suggest that the device can be used as a strain gauge or a chemical sensor.

  16. Adaptive perfectly matched layer for Wood's anomalies in diffraction gratings

    E-print Network

    Vial, Benjamin; Nicolet, André; Commandré, Mireille; Tisserand, Stéphane

    2015-01-01

    We propose an Adaptive Perfectly Matched Layer (APML) to be used in diffraction grating modeling. With a properly tailored co-ordinate stretching depending both on the incident field and on grating parameters, the APML may efficiently absorb diffracted orders near grazing angles (the so-called Wood's anomalies). The new design is implemented in a finite element method (FEM) scheme and applied on a numerical example of a dielectric slit grating. Its performances are compared with classical PML with constant stretching coefficient.

  17. Slow Light Via a Tapered Grating: Transfer Matrix Approach

    Microsoft Academic Search

    Theo P. Valkering

    2006-01-01

    Reflection properties of a nonuniform apodized Bragg grating connecting a homogeneous medium with a (half-infinite) uniform\\u000a grating are investigated for system parameters such that the group velocity in the uniform grating is low. In particular a\\u000a smooth polynomial transition of the index profile to the uniform region is considered. Exact coupled mode equations for local\\u000a Bloch amplitudes are set up

  18. Long period gratings in air-core photonic bandgap fibers.

    PubMed

    Wang, Yiping; Jin, Wei; Ju, Jian; Xuan, Haifeng; Ho, Hoi Lut; Xiao, Limin; Wang, Dongning

    2008-02-18

    Long period fiber gratings in hollow-core air-silica photonic bandgap fibers were produced by use of high frequency, short duration, CO2 laser pulses to periodically modify the size, shape and distribution of air holes in the microstructured cladding. The resonant wavelength of these gratings is highly sensitivity to strain but insensitive to temperature, bend and external refractive index. These gratings can be used as stable spectral filters and novel sensors. PMID:18542362

  19. Fiber Bragg grating (FBG) characterization and shaping by local pressure

    Microsoft Academic Search

    C. J. S. de Matos; P. Torres; L. C. G. Valente; W. Margulis; R. Stubbe

    2001-01-01

    The spatial distribution of the chirp profile of a 4-cm-long nonuniform fiber Bragg grating (FBG) was studied with the exertion of local pressure on the fiber through the application of transverse force to a small grating section (~0.3 mm). The technique was also used for spectrally shaping a previously unchirped, 18-cm-long Bragg grating, generating a narrow transmission window (~400 MHz)

  20. Observation of narrowband intrinsic spectra of Brillouin dynamic gratings.

    PubMed

    Song, Kwang Yong; Yoon, Hyuk Jin

    2010-09-01

    We experimentally demonstrate that the reflection spectrum of a Brillouin dynamic grating in a polarization-maintaining fiber can be much narrower than the intrinsic linewidth of the stimulated Brillouin scattering, matching well with the theory of a fiber Bragg grating in terms of the linewidth and the reflectivity. A 3 dB bandwidth as narrow as 10.5 MHz is observed with the Brillouin dynamic grating generated in a 9 m uniform fiber. PMID:20808382

  1. Brillouin dynamic grating in optical fibers and its applications

    Microsoft Academic Search

    Kwang Yong Song

    2009-01-01

    A novel kind of all-optical dynamic grating with the reflectance and the center wavelength controlled by another optical wave can be realized based on Brillouin scattering in polarization-maintaining optical fibers. This grating, called Brillouin dynamic grating (BDG), has proved to be useful based on its unique characteristics in several applications such as high performance distributed sensors and optically-tunable delay lines.

  2. Brillouin dynamic grating in optical fibers and its applications

    NASA Astrophysics Data System (ADS)

    Song, Kwang-Yong

    2009-11-01

    A novel kind of all-optical dynamic grating with the reflectance and the center wavelength controlled by another optical wave can be realized based on Brillouin scattering in polarization-maintaining optical fibers. This grating, called Brillouin dynamic grating (BDG), has proved to be useful based on its unique characteristics in several applications such as high performance distributed sensors and optically-tunable delay lines.

  3. Dynamic gratings in optical fibers: Synthesis and sensing applications

    NASA Astrophysics Data System (ADS)

    He, Zuyuan; Hotate, Kazuo

    2012-03-01

    We proposed two schemes of generating and localizing dynamic gratings in optical fibers: one is based on the gain saturation in erbium-doped fiber; the other is based on Brillouin scattering in the fiber. By using these dynamic gratings, fully distributed strain/temperature sensors have been demonstrated. In this presentation, we review the principles, basic schemes, and experimental demonstrations of the novel dynamic grating techniques.

  4. Subwavelength metal grating metamaterial for polarization selective optical antireflection coating

    E-print Network

    Kim, Wonkyu; Hendrickson, Joshua

    2015-01-01

    A metamaterial structure consisting of a one-dimensional metal/air-gap subwavelength grating is investigated for optical antireflection coating on germanium substrate in the infrared regime. For incident light polarized perpendicularly to the grating lines, the metamaterial exhibits effective dielectric property and Fabry-Perot like plasmon-coupled optical resonance results in complete elimination of reflection and enhancement of transmission. It is found that the subwavelength grating metamaterial antireflection structure does not require a deep subwavelength grating period, which is advantageous for device fabrication. Maximal transmittance of 93.4% with complete elimination of reflection is seen in the mid-wave infrared range.

  5. Bragg grating writing in acoustically excited optical fiber

    NASA Astrophysics Data System (ADS)

    Oliveira, Roberson A.; Cook, Kevin; Canning, John; Pohl, Alexandre A. P.

    2010-07-01

    The inscription of Bragg gratings in optical fiber under acoustic excitation is proposed and demonstrated. A permanent change in the refractive index as the period of the grating is modulated with periodic acoustic excitation during UV grating writing leads to sampling of the structure and the production of spectral combs. A physical contribution to index change through stress profiling reveals a complicated picture of UV-induced index change, well beyond simple localized defect and structural changes. The method offers the potential for tuning and tailoring conventional uniform gratings during the writing process using adjustable acoustic wave functions, an approach to control the writing process.

  6. Diffraction Gratings for High-Intensity Laser Applications

    SciTech Connect

    Britten, J

    2008-01-23

    The scattering of light into wavelength-dependent discrete directions (orders) by a device exhibiting a periodic modulation of a physical attribute on a spatial scale similar to the wavelength of light has been the subject of study for over 200 years. Such a device is called a diffraction grating. Practical applications of diffraction gratings, mainly for spectroscopy, have been around for over 100 years. The importance of diffraction gratings in spectroscopy for the measurement of myriad properties of matter can hardly be overestimated. Since the advent of coherent light sources (lasers) in the 1960's, applications of diffraction gratings in spectroscopy have further exploded. Lasers have opened a vast application space for gratings, and apace, gratings have enabled entirely new classes of laser systems. Excellent reviews of the history, fundamental properties, applications and manufacturing techniques of diffraction gratings up to the time of their publication can be found in the books by Hutley (1) and more recently Loewen and Popov (2). The limited scope of this chapter can hardly do justice to such a comprehensive subject, so the focus here will be narrowly limited to characteristics required for gratings suitable for high-power laser applications, and methods to fabricate them. A particular area of emphasis will be on maximally-efficient large-aperture gratings for short-pulse laser generation.

  7. Fabricating fiber Bragg gratings using phase modulated direct UV writing

    NASA Astrophysics Data System (ADS)

    Holmes, C.; Sima, C.; Mennea, P. L.; Carpenter, L. G.; Gates, J. C.; Smith, P. G. R.

    2014-03-01

    The authors present a direct UV writing approach to fabricate fiber Bragg gratings (FBGs) and gratings in photolithographic waveguides. The technique uses two coherent UV beams, which are focused to a small spot (~7?m diameter) at the point at which they overlap. The resulting interference pattern at the foci consists of fringes which are used to define several grating planes per exposure, giving greater design flexibility and a significantly larger accessible spectral range compared to traditional approaches. The typical index contrast during grating fabrication is observed to be 4.7×10-3, at writing speeds of 8 mm/min.

  8. Phasor analysis of atom diffraction from a rotated material grating

    SciTech Connect

    Cronin, Alexander D.; Perreault, John D. [University of Arizona, Tucson, Arizona 05721 (United States)

    2004-10-01

    An atom-surface interaction was detected by studying atom diffraction from a rotated material grating. A phasor diagram similar to the Cornu spiral was developed to explain why there are no missing orders in atom diffraction from material gratings. We also show that atom-surface interactions combined with rotated grating structures can produce asymmetric, i.e., blazed, diffraction patterns. Our conceptual discussion is supported by experimental observations with a sodium atom beam and silicon nitride gratings. The data are consistent with the nonretarded van der Waals interaction.

  9. Surface enhanced infrared spectroscopy with gold strip gratings.

    PubMed

    Wang, Tao; Nguyen, Vu Hoa; Buchenauer, Andreas; Schnakenberg, Uwe; Taubner, Thomas

    2013-04-01

    We investigate surface enhanced infrared absorption (SEIRA) spectroscopy with gold strip gratings made by standard optical lithography. By exciting surface plasmon polaritons on both air-gold and gold-substrate interfaces, the resonance of the 1D gratings is linearly tunable with the grating period. With the field enhancement at the edge of the gold strips, a SEIRA enhancement factor more than 6000 for PMMA molecules is achieved. The strong SEIRA enhancement together with the easy fabrication makes the gold strip grating a promising candidate for SEIRA experiments. PMID:23571990

  10. A millimeter wavelength radiation source using a dual grating resonator

    SciTech Connect

    Killoran, J.H.; Hacker, F.L.; Walsh, J.E. (Dartmouth Coll., Hanover, NH (United States). Dept. of Physics)

    1994-10-01

    A novel means of producing coherent radiation by passing an electron through a dual-grating resonator is presented. The observed radiation is in accordance with the Smith-Purcell dispersion relation for a single grating. Feedback is provided by a second grating. Experiments carried out at beam energies from 30--55 KeV produced radiation at wavelengths from 6 to 0.75 mm. Power measurements were used to clarify the grating-beam interaction. Indications are that operation could be easily extended to shorter wavelengths to provide an inexpensive and compact radiation source in the far-infrared.

  11. Improved layer peeling algorithm for strongly reflecting fiber gratings

    NASA Astrophysics Data System (ADS)

    Huang, Liqun; Huang, Weiping; Wang, Jinkuan; Yang, Guang

    2006-09-01

    An improved algorithm based on the layer peeling (LP) method is proposed and demonstrated. The new method is shown to be effective for mitigating the impact of numerical errors on reconstruction of coupling function for strongly reflecting Bragg gratings. As examples, a flat-top dispersion-free fiber grating and a fiber-grating dispersion compensator are designed by the improved LP method. For a chirp grating, more accurate results are demonstrated in comparison with those obtained by the integral layer peeling (ILP) method.

  12. Groove Density Measurements for the VLS grating by Diffraction Method

    SciTech Connect

    Hu, Z.W.; Yu, X.J.; Liu, Z.P.; Wang, Q.P. [NSRL, University of Science and Technology of China, Hefei, Anhui 230029 (China); Chen, Q. [Legend Computer Systems Ltd (China)

    2004-05-12

    A grating groove density measurement system is developed to measure the groove variation of VLS grating in NSRL. It has certain advantages over methods like Atomic force microscopy(AFM), Moire fringe method and long trace profiler(LTP). It is applicable to gratings of arbitrary surface shape and with arbitrary groove density distribution. The errors affecting the measurement accuracy are analyzed. The mechanical setup sketch is given. The mechanical accuracy is calibrated in order to control the uncertainty. The first result of a VLS plane grating is tested. The system accuracy ({delta}N/N) is about 2x10-4.

  13. High-resolution absolute position detection using a multiple grating

    NASA Astrophysics Data System (ADS)

    Schilling, Ulrich; Drabarek, Pawel; Kuehnle, Goetz; Tiziani, Hans J.

    1996-08-01

    To control electro-mechanical engines, high-resolution linear and rotary encoders are needed. Interferometric methods (grating interferometers) promise a resolution of a few nanometers, but have an ambiguity range of some microns. Incremental encoders increase the absolute measurement range by counting the signal periods starting from a defined initial point. In many applications, however, it is not possible to move to this initial point, so that absolute encoders have to be used. Absolute encoders generally have a scale with two or more tracks placed next to each other. Therefore, they use a two-dimensional grating structure to measure a one-dimensional position. We present a new method, which uses a one-dimensional structure to determine the position in one dimension. It is based on a grating with a large grating period up to some millimeters, having the same diffraction efficiency in several predefined diffraction orders (multiple grating). By combining the phase signals of the different diffraction orders, it is possible to establish the position in an absolute range of the grating period with a resolution like incremental grating interferometers. The principal functionality was demonstrated by applying the multiple grating in a heterodyne grating interferometer. The heterodyne frequency was generated by a frequency modulated laser in an unbalanced interferometer. In experimental measurements an absolute range of 8 mm was obtained while achieving a resolution of 10 nm.

  14. In-Core Fiber Gratings: Coupling Analysis and Synthesis

    NASA Astrophysics Data System (ADS)

    Bouzid, Ahmed

    Diffraction gratings formed in the core of optical fibers present unique means of coupling the light in and out of the fiber. These gratings can be used in a wide range of applications in fiber communications and sensors. In this dissertation, fiber-optic in-core gratings are analyzed using both rigorous and approximate methods. Local-normal -mode and scattering theories are used to develop a set of general coupled linear differential equations that describe the coupling process caused by planar gratings. Gratings that are formed at arbitrary angles with respect to the axis of the fiber are considered. Gratings with sinusoidal index variations are analyzed and shown to have a very narrow spectral widths (in the order of few Angstroms) with high diffraction efficiencies. Spectral widths and diffraction efficiencies can be controlled by changing the grating parameter; e.g. period, length, amplitude, and orientation of index modulation. Nonlinearities in index modulation, such as dc-bias, tapering, and chirp are analyzed. Approximate methods such as the First Born approximation, dielectric inhomogeneous thin film layers, and the optical-path methods are used in the analysis and have shown excellent agreement with the exact solutions especially for weak gratings. Synthesis techniques are also introduced for designing such gratings.

  15. Design of ultrabroadband internal reflection gratings with high efficiency.

    PubMed

    Bi, Qunyu; Zheng, Jiangjun; Sun, Meizhi; Yang, Xinbo; Xie, Xinglong; Lin, Zunqi

    2011-04-15

    A high-efficiency, ultrabroadband dielectric internal reflection grating with rhombus-shaped grooves is designed by a rigorous coupled-wave analysis, and an effective method for predicting spectral bandwidths of gratings from their efficiency maps is presented. The grating can be fabricated from a single dielectric material, and its reflection diffraction efficiency of the -1st order can reach more than 0.99. More importantly, an ultrabroadband top-hat diffraction spectrum with efficiency exceeding 0.98 over 170 nm wavelength wide is achieved, which makes the gratings suitable for applications associated with broadband illumination, such as ultrashort pulses. PMID:21499380

  16. Mechanics of dielectric elastomer-activated deformable transmission grating

    NASA Astrophysics Data System (ADS)

    Wang, Yin; Zhou, Jinxiong; Sun, Wenjie; Wu, Xiaohong; Zhang, Ling

    2014-09-01

    Laminating a thin layer of elastomeric grating on the surface of a prestretched dielectric elastomer (DE) membrane forms a basic design of electrically tunable transmission grating. We analyze the inhomogeneous deformation of a circular multiple-region configuration. Variation of the geometric and material parameters, as well as of the critical condition determined by loss of tension instability, is probed to aid the design of a DE-based deformable grating. The predicted changes in the grating period agree substantially with the experimental results reported by Aschwanden et al (Aschwanden et al 2007 IEEE Photon. Technol. Lett. 19 1090).

  17. Space-resolved vacuum ultraviolet spectrometer system for edge impurity and temperature profile measurement in HL-2A

    SciTech Connect

    Cui Zhengying; Fu Bingzhong; Huang Yuan; Sun Ping; Gao Yadong; Xu Yuan; Lu Ping; Wang Quanming; Ding Xuantong; Yang Qingwei; Duan Xuru [Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041 (China); Morita, Shigeru [National Institute for Fusion Science, Toki 509-5292, Gifu (Japan); Dong Chunfeng [Department of Fusion Science, Graduate University for Advanced Studies, Toki 509-5292, Gifu (Japan)

    2010-04-15

    A 1 m normal incidence vacuum ultraviolet (VUV) spectrometer has been developed for spatial distribution measurement of edge impurity line emission in the wavelength range of 300-3200 A on HL-2A tokamak. A vertical profile of the impurity line emission is measured with a space-resolved slit placed between an entrance slit and a grating of the spectrometer. Two concave 1200 grooves/mm gratings blazed at 800 and 1500 A are set on a rotatable holder in the spectrometer, which gives wavelength dispersion of 0.12 mm/A. A back-illuminated charge-coupled device is used as a detector with an image size of 6.7x26.6 mm{sup 2} (26x26 {mu}m{sup 2}/pixel). An excellent spatial resolution of 2 mm is obtained with good spectral resolution of 0.15 A when the space-resolved slit of 50 {mu}m in width is used. The space-resolved spectra thus provide three radial profiles of emission line intensity, ion temperature, and poloidal rotation. The electron temperature can be measured by the intensity ratio, e.g., CIII 2s{sup 2}-2s3p (386 A)/2s{sup 2}-2s2p (977 A). The sensitivity of the spectrometer is calibrated in situ by using the VUV bremsstrahlung continuum radiation emitted from the tokamak plasma. A good performance of the spectrometer system for the edge impurity and temperature profile measurements is presented with results on Ohmic and H-mode discharges.

  18. Design and status of an optical and near-infrared spectrometer for the IRSF 1.4m Telescope

    NASA Astrophysics Data System (ADS)

    Nagayama, Takahiro; Kurita, Mikio; Kino, Masaru; Mori, Daisuke; Kokusho, Takuma

    2012-09-01

    We present our new optical and near-infrared (NIR) spectrometer for the IRSF 1.4m telescope. The concept of it is an effective use of photons, and so we have designed it to obtain a spectrum of the 0.4-2.5?m range simultaneously and have a small number of optical surfaces in order to reduce reflection loss. Light collected by the telescope is separated into optical (0.45-0.90?m) and NIR (1.0-2.5?m) wavelengths by a dichroic entrance window, and two spectrometers are prepared, one for the optical wavelengths and another for the NIR. We use a sapphire prism in the NIR spectrometer, and a diffraction grating in the optical spectrometer. The optical design is very simple and the number of optical surfaces is 9 for optical and 10 for NIR (not including the telescope mirrors). A 1024×250 pixels CCD (optical) and a 1024×1024 HgCdTe detector array (NIR) are used. The spectral resolution will be 470@0.70?m and 380@1.8?m with a 1" slit width. A NIR slit viewer with a 3'.5 × 3'.5 field of view is also mounted. The development of the spectrometer will be complete by March 2013.

  19. Alpha-particle spectrometer experiment

    NASA Technical Reports Server (NTRS)

    Gorenstein, P.; Bjorkholm, P.

    1972-01-01

    Mapping the radon emanation of the moon was studied to find potential areas of high activity by detection of radon isotopes and their daughter products. It was felt that based on observation of regions overflown by Apollo spacecraft and within the field of view of the alpha-particle spectrometer, a radon map could be constructed, identifying and locating lunar areas of outgassing. The basic theory of radon migration from natural concentrations of uranium and thorium is discussed in terms of radon decay and the production of alpha particles. The preliminary analysis of the results indicates no significant alpha emission.

  20. Experiment M408: Beta spectrometer

    NASA Technical Reports Server (NTRS)

    Marbach, J. R.

    1971-01-01

    The beta spectrometer functioned as planned throughout the Gemini 10 mission. The cool temperatures that were recorded from the instrument during the mission were indicative that the evaporative cooler, coupled with apparently lower-than-expected spacecraft-adapter temperatures, maintained ideal operating conditions. The data facilitate a good analysis of the electron directional distribution. The omnidirectional flux that was calculated is apparently consistent with previous measurements. Representative electron spectra, measured during the Gemini 12 mission, established the apparent decay of the artificially injected electrons (from the Starfish high altitude nuclear test) to such low levels that natural trapped electrons were becoming detectable.

  1. Photometric imaging near infrared spectrometer

    NASA Technical Reports Server (NTRS)

    Goebel, J. H.; Mccreight, C. R.; Witteborn, F. C.; Stafford, P.; Moss, N.; Jared, D.

    1985-01-01

    A description of the design and performance of an imaging spectrometer intended for operation in the seven to fourteen micrometer wavelength range is presented. It is based upon a sixteen by sixteen element Si:Bi hybrid array, a circular variable filter wheel, and a microcomputer data acquisition system. The spatial-spectral photometric performances have been evaluated in the laboratory as well as field tested at astronomical observatories. The performance characteristics of the system are presented as well as laboratory and astronomical images.

  2. MODIS: Moderate Resolution Imaging Spectrometer

    NSDL National Science Digital Library

    2002-01-01

    This brochure describes the Moderate Resolution Imaging Spectrometer (MODIS) instrument on NASA's Terra satellite. The first NASA Earth Observing System (EOS) satellite, Terra, was launched on December 18, 1999, carrying five remote sensors. The most comprehensive EOS sensor is MODIS which offers a unique combination of features: it detects a wide spectral range of electromagnetic energy; it takes measurements at three spatial resolutions (levels of detail); it takes measurements all day, every day; and it has a wide field of view. This continual, comprehensive coverage allows MODIS to complete an electromagnetic picture of the globe every two days.

  3. Engine spectrometer probe and method of use

    NASA Technical Reports Server (NTRS)

    Barkhoudarian, Sarkis (Inventor); Kittinger, Scott A. (Inventor)

    2006-01-01

    The engine spectrometer probe and method of using the same of the present invention provides a simple engine spectrometer probe which is both lightweight and rugged, allowing an exhaust plume monitoring system to be attached to a vehicle, such as the space shuttle. The engine spectrometer probe can be mounted to limit exposure to the heat and debris of the exhaust plume. The spectrometer probe 50 comprises a housing 52 having an aperture 55 and a fiber optic cable 60 having a fiber optic tip 65. The fiber optic tip 65 has an acceptance angle 87 and is coupled to the aperture 55 so that the acceptance angle 87 intersects the exhaust plume 30. The spectrometer probe can generate a spectrum signal from light in the acceptance angle 506 and the spectrum signal can be provided to a spectrometer 508.

  4. Lunar mass spectrometer test program

    NASA Technical Reports Server (NTRS)

    Torney, F. L.; Dobrott, J. R.

    1972-01-01

    The procedures are described along with results obtained in a test program conducted to demonstrate the performance of a candidate lunar mass spectrometer. The instrument was designed to sample and measure gases believed to exist in the lunar atmosphere at the surface. The subject instrument consists of a cold cathode ion source, a small quadrupole mass analyzer and an off axis electron multiplier ion counting detector. The major program emphasis was placed on demonstrating instrument resolution, sensitivity and S/N ratio over the mass range 0-150 amu and over a partial pressure range from 10 to the minus 9th power to 10 to the minus 13th power torr. Ultrahigh vacuum tests were conducted and the minimum detectable partial pressure for neon, argon, krypton and xenon was successfully determined for the spectrometer using isotopes of these gases. With the exception of neon, the minimum detectable partial pressure is approximately 4 x 10 to the minus 14th power torr for the above gases.

  5. Automated mass spectrometer analysis system

    NASA Technical Reports Server (NTRS)

    Kuppermann, Aron (Inventor); Dreyer, William J. (Inventor); Giffin, Charles E. (Inventor); Boettger, Heinz G. (Inventor)

    1982-01-01

    An automated mass spectrometer analysis system is disclosed, in which samples are automatically processed in a sample processor and converted into volatilizable samples, or their characteristic volatilizable derivatives. Each volatilizable sample is sequentially volatilized and analyzed in a double focusing mass spectrometer, whose output is in the form of separate ion beams all of which are simultaneously focused in a focal plane. Each ion beam is indicative of a different sample component or different fragments of one or more sample components and the beam intensity is related to the relative abundance of the sample component. The system includes an electro-optical ion detector which automatically and simultaneously converts the ion beams, first into electron beams which in turn produce a related image which is transferred to the target of a vilicon unit. The latter converts the images into electrical signals which are supplied to a data processor, whose output is a list of the components of the analyzed sample and their abundances. The system is under the control of a master control unit, which in addition to monitoring and controlling various power sources, controls the automatic operation of the system under expected and some unexpected conditions and further protects various critical parts of the system from damage due to particularly abnormal conditions.

  6. Fractal signatures in the aperiodic Fibonacci grating.

    PubMed

    Verma, Rupesh; Banerjee, Varsha; Senthilkumaran, Paramasivam

    2014-05-01

    The Fibonacci grating (FbG) is an archetypal example of aperiodicity and self-similarity. While aperiodicity distinguishes it from a fractal, self-similarity identifies it with a fractal. Our paper investigates the outcome of these complementary features on the FbG diffraction profile (FbGDP). We find that the FbGDP has unique characteristics (e.g., no reduction in intensity with increasing generations), in addition to fractal signatures (e.g., a non-integer fractal dimension). These make the Fibonacci architecture potentially useful in image forming devices and other emerging technologies. PMID:24784044

  7. Dual polarization fiber grating laser hydrophone.

    PubMed

    Guan, Bai-Ou; Tan, Yan-Nan; Tam, Hwa-Yaw

    2009-10-26

    A novel fiber optic hydrophone based on the integration of a dual polarization fiber grating laser and an elastic diaphragm is proposed and experimentally demonstrated. The diaphragm transforms the acoustic pressure into transversal force acting on the laser cavity which changes the fiber birefringence and therefore the beat frequency between the two polarization lines. The proposed hydrophone has advantages of ease of interrogation, absolute frequency encoding, and capability to multiplex a number of sensors on a single fiber by use of frequency division multiplexing technique. PMID:19997174

  8. Fiber Bragg grating sensor network optimization

    NASA Astrophysics Data System (ADS)

    Wang, Guina; Zeng, Jie; Mu, Hao; Liang, Dakai

    2015-06-01

    This study introduces the optimization of the fiber Bragg grating (FBG) network and the load identification. Current researches on the optimal placement and reliability of the FBG network and the static load identification are generally analyzed. And then, the optimal placement of sensors and reliability of the FBG network are studied. Through the analysis of structural response characteristics, the general rules of sensors placement in structural static response parameters monitoring are proposed. The probability calculation is introduced, and the numerical analyses of the FBG sensor network reliability of several simple topologies are given.

  9. Long period gratings in highly birefringent microfibers

    NASA Astrophysics Data System (ADS)

    Jin, Wa; Xuan, Haifeng; Jin, Wei

    2014-05-01

    We report the fabrication of long-period gratings (LPGs) in highly birefringent (Hi-Bi) microfibers. The LPGs were fabricated by using a femtosecond infrared laser to modify the surface or a CO2 laser to induce micro-tapers periodically along the Hi-Bi microfibers. These LPGs have pitches from tens to hundreds of micrometers and very strong polarization dependent resonances. A LPG fabricated on a Hi-Bi microfiber with a major-diameter of ~2.8 ?m and an ellipticity of ~0.7 demonstrated a refractive index sensitivity of ~4623 nm/RIU in water.

  10. Experimental research on fiber Bragg grating hydrophone

    NASA Astrophysics Data System (ADS)

    Liu, Bo; Niu, Wencheng; Xiao, ChunXian; Kai, Guiyun; Dong, Xiaoyi

    2006-01-01

    The FBG being used as the basic sensor unit, a hydrophone sensor has been designed and manufactured. Its principle and relevant experimental result are introduced. By using the matched fiber grating demodulation technique, dynamic signal measurement with high sensitivity is realized. The frequency range of the FBG-based hydrophone is 10~3kHz with a dynamic range is 60dB. Due to the characters of FBG itself, the measure of multiple-points underwater signal can be realized conveniently by using WDM and TDM techniques.

  11. Measuring Bragg gratings in multimode optical fibers.

    PubMed

    Schmid, Markus J; Müller, Mathias S

    2015-03-23

    Fiber Bragg gratings (FBG) in multimode optical fibers provide a means for cost-effictive devices resulting in simplified and robust optic sensor systems. Parasitic mode effects in optical components of the entire measurement system strongly influence the measured multi-resonance reflection spectrum. Using a mode transfer matrix formalism we can describe these complex mode coupling effects in multimode optical systems in more detail. We demonstrate the accordance of the theory by two experiments. With this formalism it is possible to understand and optimize mode effects in multimode fiber optic systems. PMID:25837146

  12. Accurate diffraction efficiency control for multiplexed volume holographic gratings

    E-print Network

    Chen, Ray

    .1117/1.1512661] Subject terms: diffraction; gratings; holograms. Paper 020007 received Jan. 9, 2002; revised manuscript interconnect systems. The photopolymer-based volume hologram is an attractive option for making high-efficiency gratings. The advantage of photopolymers over other types of emulsion, such as dichromated gelatin

  13. Resonant reflection and absorption in grating waveguide structures

    Microsoft Academic Search

    Olaf Stenzel

    2004-01-01

    Resonant grating waveguide structures (GWS) are candidates for extreme narrow line reflection filters. In contrast to conventional dielectric mirror designs, a GWS may be composed from a single high refractive index film with a diffraction grating on top or bottom. In the high-refractive index film, a guided-mode resonance mechanism may theoretically lead to 100% reflection efficiency, while the system is

  14. Reflective silicon binary diffraction grating for visible wavelengths

    E-print Network

    Li, Jingjing

    on subwavelength resonant grating technology. Using a single lithography step we built a reflective binary grating that efficient subwavelength resonant devices for visible wavelengths can be built using silicon. © 2011 Optical with the resonantly scattered light can be used to control the phase front of the reflected light [5] and, therefore

  15. Fiber Bragg Grating Temperature Sensor for Defence and Industrial Applications

    Microsoft Academic Search

    Haftay Abadi Gebru; B. B. Padhy

    2011-01-01

    This paper presents the design and development of fiber Bragg grating (FBG) temperature sensor suitable for naval applications like temperature monitoring of onboard ships. The Bragg gratings used here have a reflection Bragg wavelength of 1550 nm and are inscribed by phase mask technique using ultraviolet (UV) laser beam at 255.3 nm. The high-resolution temperature sensor has been designed and

  16. Time Analysis of the Wavelength Shift in Fiber Bragg Gratings

    Microsoft Academic Search

    Paulo de Tarso Neves; Alexandre de Almeida Prado Pohl

    2007-01-01

    This paper presents the time analysis of the Bragg wavelength shift in fiber gratings based on the elastodynamics theory. The model is valuable for estimating an upper limit for the tuning speed when traction forces are applied to the free end of the grating. A comparison between the single-mode silica optical fiber and polymer optical fiber is performed, showing the

  17. Production and evaluation of silicon immersion gratings for infrared astronomy

    E-print Network

    Jaffe, Daniel T.

    years developing techniques for etching precisely placed grooves into monocrystalline silicon substratesProduction and evaluation of silicon immersion gratings for infrared astronomy J. P. Marsh, D. J of immersion gratings produced by fabricating grooves in silicon substrates using photolithographic patterning

  18. Illumination systems using photopolymer gratings for speckle interferometry

    Microsoft Academic Search

    Maurice P. Whelan; Colin Forno; Suzanne Martin; Feidhlim O'Neill; Vincent Toal

    1999-01-01

    This study describes the use of diffractive optical elements (DOEs) namely phase gratings, for the simplification of typical illumination schemes employed in digital speckle pattern interferometry. The diffraction gratings are recorded in a photopolymer material that delivers by high diffraction efficiency in transmission but which requires relatively low exposure energies. A significant advantage of this material is that it is

  19. Influence of nonideal chirped fiber grating characteristics on dispersion cancellation

    Microsoft Academic Search

    K. Ennser; M. Ibsen; M. Durkin; M. N. Zervas; R. I. Laming

    1998-01-01

    The effect of nonideal dispersion and reflection characteristics of chirped fiber gratings on the performance of 10-Gb\\/s nonreturn-to-zero-transmission systems operating over standard fiber is investigated. The system penalty for different amplitude and period ripples are quantified. Analyses of an experimental grating confirm that current fabrication technology can meet the requirements for <1-dB-penalty operation

  20. Coupled-wave analysis of apodized volume gratings

    E-print Network

    Glebov, Leon

    ", Appl. Opt. 33, 2795-2803 (1994). 3. A. Marrakchi and K. Rastani, "Free-space holographic grating- fiber laser beams by PTR Bragg grating", In Advances in Fiber Devices, L. N. Durvasula, Editor communications for holographic optical elements. The narrow-band diffractive property of holograms can

  1. Linearized Bragg grating assisted electro-optic modulator.

    PubMed

    Khurgin, Jacob B; Morton, Paul A

    2014-12-15

    We propose a new linearized electro-optic modulator in which linearization is achieved by modulating the index of a Bragg grating reflector placed in the arm(s) of a Michelson Interferometer. This grating-assisted Michelson (GAMI) modulator can operate as either an intensity or amplitude modulator, and is shown to significantly improve the linearity of microwave photonics links. PMID:25503037

  2. Analysis of Induced-Birefringence Effects on Fiber Bragg Gratings

    Microsoft Academic Search

    Rachid Gafsi; Mahmoud A. El-Sherif

    2000-01-01

    This paper reports the birefringence effects on fiber Bragg grating (FBG) in sensors, optical communications systems, and devices. We have studied and analyzed the optical and mechanical property changes of FBG when the grating zone is subjected to a static transverse load in the case of plane strain and stress. The results presented for plane strain confirm the calculations established

  3. Interferometric fiber sensor with a chirped Bragg grating sensing element

    NASA Astrophysics Data System (ADS)

    Kersey, Alan D.; Davis, Michael A.

    1994-09-01

    An interferometric sensor based on the use of a chirped Bragg grating reflector is described. It is shown that strain applied to the chirped grating can induce a large path length change in an interferometer, equivalent to that obtained with a multi-meter length of fiber when strained directly.

  4. Nanoparticle-Enhanced Diffraction Gratings for Ultrasensitive Surface Plasmon Biosensing

    E-print Network

    Nanoparticle-Enhanced Diffraction Gratings for Ultrasensitive Surface Plasmon Biosensing Alastair W in a surface plasmon resonance geometry is observed due to the optical coupling of the planar surface plasmons in the grating to the localized surface plasmons in the gold nanoparticles. As a first example

  5. A theoretical analysis of etched grating couplers for integrated optics

    Microsoft Academic Search

    K. Ogawa; W. Chang; B. Sopori; F. Rosenbaum

    1973-01-01

    Grating couplers provide an attractive method for the excitation of optical thin-film waveguides. We present here a perturbation analysis of etched or deposited grating couplers based upon both the transmission line and the Green's Function approaches, which predict the coupling efficiency, the output radiation beamwidth, the angular dependence of excitation, and the intensities of the other orders of the diffracted

  6. Chirped Brillouin dynamic gratings for storing and compressing light.

    PubMed

    Winful, Herbert G

    2013-04-22

    We demonstrate theoretically that chirped dynamic gratings can be created in optical fibers through stimulated Brillouin scattering with frequency-chirped "signal" and "write" pulses. When the grating is interrogated with a third pulse of the opposite chirp, a compressed signal pulse is retrieved. This provides a method to regenerate stored pulses and enhance signal levels for communications applications. PMID:23609709

  7. Enhanced and suppressed birefringence in fiber Bragg gratings

    Microsoft Academic Search

    Suresh Pereira; J. E. Sipe; R. E. Slusher; Stefan Spalter

    2002-01-01

    We demonstrate theoretically and experimentally that two orthogonal polarizations of light see an unequal index contrast in a UV-induced fiber Bragg grating. We have found that in a Bragg grating the phase-velocity mismatch is a function of detuning, and hence we can introduce an effective birefringence. The description of the polarization dynamics that we developed was confirmed by a set

  8. Numerical solution of an inverse diffraction grating problem from ...

    E-print Network

    2013-02-02

    Feb 5, 2013 ... design problems in diffractive optics, it is intended to design a grating structure that ... dimensional transverse electric (TE) case for perfectly con- ducting gratings. .... ?f directed into ?f . Our goal in this paper is to study an inverse problem of the ..... The research of G. Bao was supported in part by NSF grants.

  9. Micromachined Vibratory Diffraction Grating Scanner for Multiwavelength Collinear Laser Scanning

    Microsoft Academic Search

    Guangya Zhou; Fook Siong Chau

    2006-01-01

    This paper presents an effective method to achieve multiwavelength collinear laser scanning using micromachined vibratory grating scanners, which have the potential to scan at high frequencies without the optical performance degradation resulting from dynamic nonrigid-body deformation. An optical simulation model has been developed to predict the scanning patterns of the vibratory grating scanners. The proposed multiwavelength collinear scanning method was

  10. Diffusion relaxation of photoinduced gratings in polyvinyl acetate latex films

    NASA Astrophysics Data System (ADS)

    Veniaminov, A. V.; Bartsch, E.

    2011-03-01

    The features of the postexposure relaxation of holographic gratings recorded in inhomogeneous polyvinyl acetate latex films with photosensitive agents (photochromic molecules of fulgide dyes and phenanthrenequinone) have been considered. The diffusion coefficients and rms displacements of izomerized probe in polymer latex particles and aqueous environment are determined within the model of two diffusion states. The effective diffusion coefficient of the molecular probe, which is responsible for the relaxation of gratings, increases with an increase in their period in wet films, whereas in dry films, this parameter is independent of the grating period. In the films subjected to high-temperature treatment the effective diffusion coefficient decreases with an increase in the grating period. The successive stages of grating relaxation in latex films with phenanthrenequinone are related to the diffusion of free molecules, radicals, and polymer chains, as well as to the local displacement of macromolecular segments at distances of 5-25 nm.

  11. Mirror-grating tuning arrangement for high resolution lasers

    NASA Technical Reports Server (NTRS)

    McDermid, Iain S. (Inventor); Pacala, Thomas J. (Inventor)

    1985-01-01

    A tuning arrangement (10) for a tunable laser comprises a single holographic grating (12) and two flat surface reflective mirrors (13 and 14). The beam (15) from the laser cavity is incident on the grating at a grazing angle for optimum beam expansion. The diffracted beam propogates from the grating to the first mirror (13), therefrom to the second mirror (14) and is reflected at the Littrow angle to the grating, whereat it is diffracted a second time and returned to the second mirror (14) for reflection to the first mirror (13). Therefrom it is reflected back to the grating. After undergoing a third diffraction it is directed back into the cavity for further amplification.

  12. Low-threshold grating-coupled surface-emitting lasers

    NASA Astrophysics Data System (ADS)

    Welch, D. F.; Parke, R.; Hardy, A.; Streifer, W.; Scifres, D. R.

    1989-08-01

    The high threshold current densities of single quantum well separate confinement heterostructure grating-coupled surface-emitting lasers are shown to result from a combination of inadequate gain in the lowest quantum state and the wavelength selective properties of the grating reflectors. The situation is aggravated by the saturable absorption loss in the grating sections and sizeable scattering losses at the etch step between gain and grating regions. Grating-coupled surface-emitting lasers with 50-micron-wide broad-area double quantum well active regions are reported with threshold currents reduced by a factor of 3 and with improved differential efficiency. Measurements of gain saturation of single quantum wells are presented.

  13. SU8 inverted-rib waveguide Bragg grating filter.

    PubMed

    Huang, Cheng-Sheng; Wang, Wei-Chih

    2013-08-01

    A polymeric SU8 inverted-rib waveguide Bragg grating filter fabricated using reactive ion etching (RIE) and solvent assisted microcontact molding (SAMIM) is presented. SAMIM is one kind of soft lithography. The technique is unique in that a composite hard-polydimethysiloxane/polydimethysiloxane stamp is used to transfer the grating pattern onto an inverted SU8 rib waveguide system. The composite grating stamp can be used repeatedly several times without degradation. Using this stamp and inverter-rib waveguide structure, the Bragg grating filter fabrication can be significantly simplified. The experiment result shows an attenuation dip in the transmission spectra, with a value of -7 dBm at 1550 nm for a grating with a period of 0.492 ?m on an inverted-rib waveguide with 6.6 ?m width and 4 ?m height. PMID:23913077

  14. Towards Single Slit Grating Interferometry Utilizing Nano-Fabricated Structures

    NASA Astrophysics Data System (ADS)

    Barwick, Brett; Gronniger, Glen; Gao, Hong; Batelaan, Herman

    2004-05-01

    An optical grating mounted on a device can be used to determine its position accurately. We use a lens to focus a laser beam onto the grating to partially overlap the diffracted beams. This results in a very simple interferometer. Counting the fringes determines the position of the device. Placing a single slit in front of the grating instead of a lens will also make the diffracted beams partially overlap. We are currently exploring the matter optics analogue of this idea, to demonstrate that the diffracted electron beams emanating from a nanofabricated grating are coherent. We made a 100 nm slit by ion milling and have seen its single slit diffraction pattern. We have combined the 100 nm single slit with a 100 nm grating, and current attempts are underway to observe the resultant interference fringes. Work supported by NSF, DOD-EPSCOR

  15. Miniature pulse compressor of deep-etched gratings.

    PubMed

    Jia, Wei; Zhou, Changhe; Feng, Jijun; Dai, Enwen

    2008-11-10

    We propose a miniature pulse compressor that can be used to compensate the group velocity dispersion that is produced by a commercial femtosecond laser cavity. The compressor is composed of two identical highly efficient deep-etched transmissive gratings. Compared with prism pairs, highly efficient deep-etched transmissive grating pairs are lightweight and small. With an optimized groove depth and a duty cycle, 98% diffraction efficiency of the -1 transmissive order can be achieved at a wavelength of 800 nm under Littrow conditions. The deep-etched gratings are fabricated in fused silica by inductively coupled plasma etching. With a pair of the fabricated gratings, the input positively chirped 73.9 fs pulses are neatly compressed into the nearly Fourier transform-limited 43.2 fs pulses. The miniature deep-etched grating-based pulse compressor should be of interest for practical applications. PMID:19002230

  16. Grating image with desired shaped dots

    NASA Astrophysics Data System (ADS)

    Honma, Hideaki; Toda, Toshiki; Takahashi, Susumu; Sawamura, Chikara; Iwata, Fujio

    2000-03-01

    A new type of Grating Image we dominate as `Sparklegram' is presented. The Sparklegram is characterized because it provides high quality and better design flexibility. These features are achieved by constructing it with shaped dots as desired. Each dot can be designed as an individual shape, for example, a star or a triangle. As dot shapes, we can use not only geometric patterns, but also some kind of symbols. Not only flexibility of each consists dot shape, but also the quality of reconstructed image is remarkably increased too. Because of these features, the constructed image with the new type of Grating Image, Sparklegram has high quality and high flexibility. It can be applied to security use, for example on credit-cards, tickets, etc., and also can be applied to the package of software products, CDs, videos and other kind of items requiring security. And with these features of flexibility and high quality, Sparklegram has also advantages to be applied to other use, for example amusement use, comics and game characters' goods and packages.

  17. An extreme ultraviolet spectrometer experiment for the Shuttle Get Away Special Program

    NASA Technical Reports Server (NTRS)

    Conway, R. R.; Mccoy, R. P.; Meier, R. R.; Mount, G. H.; Prinz, D. K.; Young, J. M.; Carruthers, G. R.

    1984-01-01

    An extreme ultraviolet (EUV) spectrometer experiment operated successfully during the STS-7 mission in an experiment to measure the global and diurnal variation of the EUV airglow. The spectrometer is an F 3.5 Wadsworth mount with mechanical collimator, a 75 x 75 mm grating, and a bare microchannel plate detector providing a spectral resolution of 7 X FWHM. Read-out of the signal is through discrete channels or resistive anode techniques. The experiment includes a microcomputer, 20 Mbit tape recorder, and a 28V, 40 Ahr silver-zinc battery. It is the first GAS payload to use an opening door. The spectrometer's 0.1 x 4.2 deg field of view is pointed vertically out of the shuttle bay. During the STS-7 flight data were acquired continuously for a period of 5 hours and 37 minutes, providing spectra of the 570 A to 850 A wavelength region of the airglow. Five diurnal cycles of the 584 A emission of neutral helium and the 834 A emission of ionized atomic oxygen were recorded. The experiment also recorded ion events and pressure pulses associated with thruster firings. The experiment is to fly again on Mission 41-F.

  18. Millimeter-wave spectrum analyzer using slanted optical gratings

    NASA Astrophysics Data System (ADS)

    Lee, Kueiming Max

    The success of acousto-optic type Bragg cells in analyzing radio-frequency signals up to the limitation of 2 GHz has motivated a search for higher frequency spectrum analysis methods. In this dissertation, a novel optical grating approach is presented. The approach uses the diffraction of millimeter-wave (2 GHz to 200 GHz) modulated optical waves scattered from a long slanted grating. The optical waves are diffracted by the slanted grating, whereas the millimeter-wave modulation is in effect reflected by the grating substrate, producing a conversion of temporal to spatial modulation. This conversion is accomplished using a long slanted holographic grating or an array of fiber gratings accessed in a raster scan format. Thus, a compact and high resolution millimeter-wave spectrum analyzer is realized in a novel approach. In the first part of this dissertation, a holographic grating implementation is simulated using CODE V. The diffraction intensity spread function on the detector determines the minimum resolving frequency, the maximum frequency bandwidth, and the alignment tolerance of each component. The second part of the dissertation explores the use of a tilted fiber phase grating to diffract the modulated RF optical signal out of the fiber. A mathematical model based on perturbation analysis is derived and used to describe the radiation mode behavior, including scattering direction and radiation power. Simulation results for a system based on a 2 cm long, fiber phase grating tilted 45o are presented. In the third part of the dissertation, a fiber grating wrapped in Cornu spiral format is simulated to investigate the feasibility of a coiled type spectrum analyzer. The last part of the dissertation investigates a heterodyne channelizer approach for improving signal resolution. Simulation results that verify operation by providing the signal spectrum on the detector array, the SNR, and the minimum frequency resolution are presented.

  19. Optimization for grating length of 980nm single-mode semiconductor laser with dual fiber Bragg grating

    Microsoft Academic Search

    Yize Huang; Yi Li; Haifang Wang; Xiaojing Yu; Hu Zhang; Wei Zhang; Huiqun Zhu

    2009-01-01

    The analytical expression of transmittivity and reflectivity of dual fiber Bragg grating (FBG) and the gain equations of the laser are obtained by the coupled mode theory. The laser gain curve is studied through the length of dual FBG and optical fiber length between two gratings under coherence collapse. The relative parameters have been optimized to get the best mode-stabilizing

  20. Multimode optical fiber based spectrometers

    E-print Network

    Redding, Brandon; Cao, Hui

    2013-01-01

    A standard multimode optical fiber can be used as a general purpose spectrometer after calibrating the wavelength dependent speckle patterns produced by interference between the guided modes of the fiber. A transmission matrix was used to store the calibration data and a robust algorithm was developed to reconstruct an arbitrary input spectrum in the presence of experimental noise. We demonstrate that a 20 meter long fiber can resolve two laser lines separated by only 8 pm. At the other extreme, we show that a 2 centimeter long fiber can measure a broadband continuous spectrum generated from a supercontinuum source. We investigate the effect of the fiber geometry on the spectral resolution and bandwidth, and also discuss the additional limitation on the bandwidth imposed by speckle contrast reduction when measuring dense spectra. Finally, we demonstrate a method to reduce the spectrum reconstruction error and increase the bandwidth by separately imaging the speckle patterns of orthogonal polarizations. The mu...

  1. Lunar orbital mass spectrometer experiment.

    NASA Technical Reports Server (NTRS)

    Hoffman, J. H.; Hodges, R. R., Jr.; Evans, D. E.

    1972-01-01

    One of the Orbital Science experiments on Apollo 15 was a mass spectrometer designed to measure the composition and distribution of the lunar atmosphere. It operated for nearly 90 hours, producing spectra of an unexpectedly complex nature, indicating that many complex gas molecules exist in the vicinity of the spacecraft. The most plausible explanation is that there was continual vaporization of frozen or liquid drops of water, fuel, or other matter that had been ejected from the spacecraft with small relative velocity so that these particles remained in nearby orbits. The search for naturally occurring gases in these spectra involves a statistical analysis of the data which has not been completed to date. A theoretical prediction regarding the possibilities of detecting lunar volcanism from orbit is included.

  2. Lunar mass spectrometer test program

    NASA Technical Reports Server (NTRS)

    Torney, F. L.; Dobrott, J. R.

    1971-01-01

    The procedures used and the results are described, which were obtained in a test program to demonstrate the performance of a candidate lunar mass spectrometer. The instrument was designed to sample and measure gases believed to exist in the lunar atmosphere at the surface. The instrument consists of a cold cathode ion source, a small quadrupole mass analyzer, and an off-axis electron multiplier ion-counting detector. Instrument resolution, sensitivity, and S/N ratio were demonstrated over the mass range 0-150 amu and over a partial pressure range from ntorr to ptorr. The subject analyzer was also prepared for extended testing, in conjunction with two other candidate instruments, in a large molecular beam vacuum facility.

  3. ExoMars Raman laser spectrometer overview

    Microsoft Academic Search

    F. Rull; A. Sansano; E. Díaz; C. P. Canora; A. G. Moral; C. Tato; M. Colombo; T. Belenguer; M. Fernández; J. A. R. Manfredi; R. Canchal; B. Dávila; A. Jiménez; P. Gallego; S. Ibarmia; J. A. R. Prieto; A. Santiago; J. Pla; G. Ramos; C. González

    2010-01-01

    The Raman Laser Spectrometer (RLS) is one of the Pasteur Payload instruments, within the ESA's Aurora Exploration Programme, ExoMars mission. The RLS Instrument will perform Raman spectroscopy on crushed powered samples deposited on a small container after crushing the cores obtained by the Rover's drill system. This is the first time that a Raman spectrometer will be launched in an

  4. Lunar Mass Spectrometer Design Verification Thermal

    E-print Network

    Rathbun, Julie A.

    the testing of the LMS Prototype model in the BxA Thermal Vacuum Test Chamber. 2. 0 INTRODUCTION The LunarLunar Mass Spectrometer Design Verification Thermal Vacuum Test LUNAR MASS SPECTROMETER DESIGN VERIFICATION THERMAL VACUUM TEST REPORT Prepared By: Approved By: NO. RI!V. MO. ATM-1097 1 40 PAGI OF DATI 4

  5. Modeling of an infrared micro-spectrometer

    E-print Network

    Modeling of an infrared stationary micro-spectrometer integrated on a focal plane array S. Mouzali-SPECTROMETER INTEGRATED ON A FOCAL PLANE ARRAY Salima Mouzali (1) , Sidonie Lefebvre (1) , Sylvain Rommeluère (1) , Yann transform interferometer integrated on a classical Mercury-Cadmium-Telluride Focal Plane Array (FPA), of 640

  6. ELECTRON SPECTROMETER WITH TOROIDAL MAGNETIC FIELD

    Microsoft Academic Search

    A. E. Dubinov; N. V. Minashkin; V. D. Selemir; N. V. Stepanov; V. E. Vatrunin

    1993-01-01

    The spectrometer allows to measure the spectrum of the electron beam, generated in the magnetized diode. Principle of the spectrometer's operation consists in spatial separation of Merent energies particles in gradient static magnetic field. Numerical integration of electron movement equations in the toroidal magnetic field %l\\/r -manner, is consistent with the experimental results received at 1-3000 accelerator. The results of

  7. The Geostationary Fourier Transform Spectrometer

    NASA Technical Reports Server (NTRS)

    Key, Richard; Sander, Stanley; Eldering, Annmarie; Miller, Charles; Frankenberg, Christian; Natra, Vijay; Rider, David; Blavier, Jean-Francois; Bekker, Dmitriy; Wu, Yen-Hung

    2012-01-01

    The Geostationary Fourier Transform Spectrometer (GeoFTS) is an imaging spectrometer designed for an earth science mission to measure key atmospheric trace gases and process tracers related to climate change and human activity. The GeoFTS instrument is a half meter cube size instrument designed to operate in geostationary orbit as a secondary "hosted" payload on a commercial geostationary satellite mission. The advantage of GEO is the ability to continuously stare at a region of the earth, enabling frequent sampling to capture the diurnal variability of biogenic fluxes and anthropogenic emissions from city to continental scales. The science goal is to obtain a process-based understanding of the carbon cycle from simultaneous high spatial resolution measurements of carbon dioxide (CO2), methane (CH4), carbon monoxide (CO), and chlorophyll fluorescence (CF) many times per day in the near infrared spectral region to capture their spatial and temporal variations on diurnal, synoptic, seasonal and interannual time scales. The GeoFTS instrument is based on a Michelson interferometer design with a number of advanced features incorporated. Two of the most important advanced features are the focal plane arrays and the optical path difference mechanism. A breadboard GeoFTS instrument has demonstrated functionality for simultaneous measurements in the visible and IR in the laboratory and subsequently in the field at the California Laboratory for Atmospheric Remote Sensing (CLARS) observatory on Mt. Wilson overlooking the Los Angeles basin. A GeoFTS engineering model instrument is being developed which will make simultaneous visible and IR measurements under space flight like environmental conditions (thermal-vacuum at 180 K). This will demonstrate critical instrument capabilities such as optical alignment stability, interferometer modulation efficiency, and high throughput FPA signal processing. This will reduce flight instrument development risk and show that the GeoFTS design is mature and flight ready.

  8. A New Optical Aerosol Spectrometer

    NASA Technical Reports Server (NTRS)

    Fonda, Mark; Malcolmson, Andrew; Bonin, Mike; Stratton, David; Rogers, C. Fred; Chang, Sherwood (Technical Monitor)

    1998-01-01

    An optical particle spectrometer capable of measuring aerosol particle size distributions from 0.02 to 100 micrometers has been developed. This instrument combines several optical methods in one, in-situ configuration; it can provide continuous data collection to encompass the wide dynamic size ranges and concentrations found in studies of modeled planetary atmospheres as well as terrestrial air quality research. Currently, the system is incorporated into an eight liter capacity spherical pressure vessel that is appropriate both for flowthrough and for in-situ particle generation. The optical sizing methods include polarization ratio, The scattering, and forward scattering detectors, with illumination from a fiber-coupled, Argon-ion laser. As particle sizes increase above 0.1 micrometer, a customized electronics and software system automatically shifts from polarization to diffraction-based measurements as the angular scattering detectors attain acceptable signal-to-noise ratios. The number concentration detection limits are estimated to be in the part-per-trillion (ppT by volume) range, or roughly 1000 submicron particles per cubic centimeter. Results from static experiments using HFC134A (approved light scattering gas standard), flow-through experiments using sodium chloride (NaCl) and carbon particles, and dynamic 'Tholin' (photochemical produced particles from ultraviolet (UV)-irradiated acetylene and nitrogen) experiments have been obtained. The optical spectrometer data obtained with particles have compared well with particle sizes determined by electron microscopy. The 'Tholin' tests provided real-time size and concentration data as the particles grew from about 30 nanometers to about 0.8 micrometers, with concentrations ranging from ppT to ppB, by volume. Tests are still underway, to better define sizing accuracy and concentration limits, these results will be reported.

  9. The Geostationary Fourier Transform Spectrometer

    NASA Technical Reports Server (NTRS)

    Key, Richard; Sander, Stanley; Eldering, Annmarie; Blavier, Jean-Francois; Bekker, Dmitriy; Manatt, Ken; Rider, David; Wu, Yen-Hung

    2012-01-01

    The Geostationary Fourier Transform Spectrometer (GeoFTS) is an imaging spectrometer designed for a geostationary orbit (GEO) earth science mission to measure key atmospheric trace gases and process tracers related to climate change and human activity. GEO allows GeoFTS to continuously stare at a region of the earth for frequent sampling to capture the variability of biogenic fluxes and anthropogenic emissions from city to continental spatial scales and temporal scales from diurnal, synoptic, seasonal to interannual. The measurement strategy provides a process based understanding of the carbon cycle from contiguous maps of carbon dioxide (CO2), methane (CH4), carbon monoxide (CO), and chlorophyll fluorescence (CF) collected many times per day at high spatial resolution (2.7kmx2.7km at nadir). The CO2/CH4/CO/CF measurement suite in the near infrared spectral region provides the information needed to disentangle natural and anthropogenic contributions to atmospheric carbon concentrations and to minimize uncertainties in the flow of carbon between the atmosphere and surface. The half meter cube size GeoFTS instrument is based on a Michelson interferometer design that uses all high TRL components in a modular configuration to reduce complexity and cost. It is self-contained and as independent of the spacecraft as possible with simple spacecraft interfaces, making it ideal to be a "hosted" payload on a commercial communications satellite mission. The hosted payload approach for measuring the major carbon-containing gases in the atmosphere from the geostationary vantage point will affordably advance the scientific understating of carbon cycle processes and climate change.

  10. Optical design of the Moderate Resolution Imaging Spectrometer - Tilt (MODIS-T) for the Earth Observing System (Eos)

    NASA Technical Reports Server (NTRS)

    Maymon, Peter W.

    1991-01-01

    The Moderate Resolution Imaging Spectrometer (MODIS) is an Earth viewing sensor that is planned as a facility instrument for the Earth Observing System (Eos) scheduled to begin functioning in the late 1990's. The MODIS is composed of two mutually supporting sensors one of which is MODIS-T, where 'T' signifies a tiltable along-track field of view. MODIS-T is a 32 channel imaging spectrometer with a required 10 nm to 15 nm spectral resolution (FWHM) in the 400 nm to 880 nm spectral range with less than 2.3 percent instrument induced linear polarization. The instrument provides at nadir a 33 km by 1500 km swath with a 1.1 km spatial resolution and an along-track pointing capability of +/- 50 deg about nadir. The heart of the optical design consists of a f/3 grating-type reflecting Schmidt camera.

  11. 21 CFR 862.2860 - Mass spectrometer for clinical use.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Mass spectrometer for clinical use. 862...Laboratory Instruments § 862.2860 Mass spectrometer for clinical use. (a) Identification. A mass spectrometer for clinical use is...

  12. 21 CFR 862.2860 - Mass spectrometer for clinical use.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Mass spectrometer for clinical use. 862...Laboratory Instruments § 862.2860 Mass spectrometer for clinical use. (a) Identification. A mass spectrometer for clinical use is...

  13. 21 CFR 862.2860 - Mass spectrometer for clinical use.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Mass spectrometer for clinical use. 862...Laboratory Instruments § 862.2860 Mass spectrometer for clinical use. (a) Identification. A mass spectrometer for clinical use is...

  14. 21 CFR 862.2860 - Mass spectrometer for clinical use.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Mass spectrometer for clinical use. 862...Laboratory Instruments § 862.2860 Mass spectrometer for clinical use. (a) Identification. A mass spectrometer for clinical use is...

  15. 21 CFR 862.2860 - Mass spectrometer for clinical use.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Mass spectrometer for clinical use. 862...Laboratory Instruments § 862.2860 Mass spectrometer for clinical use. (a) Identification. A mass spectrometer for clinical use is...

  16. Tunable phase-shifted fiber Bragg grating based on femtosecond laser fabricated in-grating bubble.

    PubMed

    Liao, Changrui; Xu, Lei; Wang, Chao; Wang, D N; Wang, Yiping; Wang, Qiao; Yang, Kaiming; Li, Zhengyong; Zhong, Xiaoyong; Zhou, Jiangtao; Liu, Yingjie

    2013-11-01

    We present a type of phase-shifted fiber Bragg gratings based on an in-grating bubble fabricated by femtosecond (fs) laser ablation together with a fusion-splicing technique. A microchannel vertically crossing the bubble is drilled by fs laser to allow liquid to flow in or out. By filling different refractive index (RI) liquid into the bubble, the phase-shift peak is found to experience a linear red shift with the increase of RI, while little contribution to the change of phase shift comes from the temperature and axial strain. Therefore, such a PS-FBG could be used to develop a promising tunable optical filter and sensor. PMID:24177122

  17. Simultaneous directional bending and temperature measurement with overlapping long period grating and fiber Bragg grating structure

    NASA Astrophysics Data System (ADS)

    Wang, Li; Zhang, Weigang; Geng, Pengcheng; Gao, Shecheng; Li, Jieliang; Bai, Zhiyong; Chen, Lei; Zhang, Shanshan; Liu, Yongji; Yan, Tieyi

    2014-05-01

    A simple and compact device for simultaneous directional bending and temperature sensing is proposed and demonstrated. The device is constructed by overlapping a long period grating (LPG) on a fiber Bragg grating (FBG), and is capable of measuring the directional bending and the temperature at the same position. The LPG written with CO2 laser irradiation has a cross asymmetrical refractive modulation and the FBG is formed by UV laser exposure in the fiber core. The cross-sensitivity between measurement of the directional bending and of the temperature of an LPG is effectively eliminated by solving a matrix equation, by considering the temperature response characteristics of FBG. Experimental results show that the bending and temperature sensitivities are - 6.819 nm m-1 in a range from -2 to 2 m-1 and 10.25 pm °C-1, respectively.

  18. Temperature-insensitive arrayed waveguide grating demodulation technique for fiber Bragg grating sensors

    NASA Astrophysics Data System (ADS)

    Li, Hongqiang; Li, Yang; Li, Enbang; Dong, Xiaye; Bai, Yaoting; Liu, Yu; Zhou, Wenqian

    2013-10-01

    As the output characteristics of arrayed waveguide grating (AWG) can be affected by temperature, the output spectrum central wavelength ?i of every channel has a tendency to drift with the temperature. To improve demodulation accuracy, this paper presents a type of AWG demodulation algorithm with temperature compensation. This algorithm assumes that under the same environment, with similarly changing temperatures of AWG and fiber Bragg grating (FBG), the AWG central wavelength is replaced with the expression that includes ?T, and the values of AWG and of FBG which change with the temperature (?T) are integrated. The experiment result shows that when temperature compensation is added in the demodulation technique, the correlation coefficient r of the demodulation result is 0.997, which means that the curve has good consistency and can be measured repeatedly. This also proves the rightness of the technique. The application of this technique for smart clothing is mentioned, which indicates its feasibility.

  19. Miniaturized imaging spectrometer based on Fabry-Perot MOEMS filters and HgCdTe infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Velicu, S.; Buurma, C.; Bergeson, J. D.; Kim, Tae Sung; Kubby, J.; Gupta, N.

    2014-05-01

    Imaging spectrometry can be utilized in the midwave infrared (MWIR) and long wave infrared (LWIR) bands to detect, identify and map complex chemical agents based on their rotational and vibrational emission spectra. Hyperspectral datasets are typically obtained using grating or Fourier transform spectrometers to separate the incoming light into spectral bands. At present, these spectrometers are large, cumbersome, slow and expensive, and their resolution is limited by bulky mechanical components such as mirrors and gratings. As such, low-cost, miniaturized imaging spectrometers are of great interest. Microfabrication of micro-electro-mechanicalsystems (MEMS)-based components opens the door for producing low-cost, reliable optical systems. We present here our work on developing a miniaturized IR imaging spectrometer by coupling a mercury cadmium telluride (HgCdTe)-based infrared focal plane array (FPA) with a MEMS-based Fabry-Perot filter (FPF). The two membranes are fabricated from silicon-oninsulator (SOI) wafers using bulk micromachining technology. The fixed membrane is a standard silicon membrane, fabricated using back etching processes. The movable membrane is implemented as an X-beam structure to improve mechanical stability. The geometries of the distributed Bragg reflector (DBR)-based tunable FPFs are modeled to achieve the desired spectral resolution and wavelength range. Additionally, acceptable fabrication tolerances are determined by modeling the spectral performance of the FPFs as a function of DBR surface roughness and membrane curvature. These fabrication non-idealities are then mitigated by developing an optimized DBR process flow yielding high-performance FPF cavities. Zinc Sulfide (ZnS) and Germanium (Ge) are chosen as the low and the high index materials, respectively, and are deposited using an electron beam process. Simulations are presented showing the impact of these changes and non-idealities in both a device and systems level.

  20. Design of a high-efficiency extreme ultraviolet overview spectrometer system for plasma impurity studies on the stellarator experiment Wendelstein 7-X

    NASA Astrophysics Data System (ADS)

    Biel, W.; Bertschinger, G.; Burhenn, R.; König, R.; Jourdain, E.

    2004-10-01

    The design for a set of four high-efficiency vacuum ultraviolet/extreme ultraviolet (VUV/XUV) spectrometers has been developed, which shall be used for plasma impurity monitoring and impurity transport studies on the stellarator experiment Wendelstein 7-X (W7-X). The new high-efficiency XUV overview spectrometer (HEXOS) system covers the wavelength range from 2.5 to 160 nm, divided into four subsections with some overlapping, thus achieving a complete coverage of prominent spectral lines from the relevant impurity elements. Taking into account spectrometer geometries and detector geometries, toroidal holographic diffraction gratings are numerically optimized to maximize the total throughput while maintaining good spectral resolution. The performance of the spectrometers is tested and optimized by means of ray tracing calculations. In order to prove the potential for line identification as well as the expected levels of signal intensity and noise figures of the new systems, spectra are simulated using the impurity transport code STRAHL. Under typical plasma conditions on W7-X the new spectrometers will allow clear identification of all relevant impurity elements in the plasma. The large collected photon flux results in a high accuracy for the measured line intensities, even when operating the spectrometers at spectra rates of 1000/s.