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Sample records for binary diffraction gratings

  1. Phasor analysis of binary diffraction gratings with different fill factors

    International Nuclear Information System (INIS)

    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 power can be easily obtained without applying the usual Fourier transform operations required for these calculations. The proposed phasor technique is mathematically equivalent to the Fourier transform calculation of the diffraction order amplitude, and it can be useful to explain binary diffraction gratings in a simple manner in introductory physics courses. This theoretical analysis is illustrated with experimental results using a liquid crystal device to display diffraction gratings with different fill factors

  2. Phasor analysis of binary diffraction gratings with different fill factors

    Energy Technology Data Exchange (ETDEWEB)

    MartInez, Antonio [Departamento de Ciencia de Materiales, Optica y TecnologIa Electronica, Universidad Miguel Hernandez, 03202 Elche (Spain); Sanchez-Lopez, Ma del Mar [Instituto de BioingenierIa y Departamento de Fisica y Arquitectura de Computadores, Universidad Miguel Hernandez, 03202 Elche (Spain); Moreno, Ignacio [Departamento de Ciencia de Materiales, Optica y TecnologIa Electronica, Universidad Miguel Hernandez, 03202 Elche (Spain)

    2007-09-11

    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 power can be easily obtained without applying the usual Fourier transform operations required for these calculations. The proposed phasor technique is mathematically equivalent to the Fourier transform calculation of the diffraction order amplitude, and it can be useful to explain binary diffraction gratings in a simple manner in introductory physics courses. This theoretical analysis is illustrated with experimental results using a liquid crystal device to display diffraction gratings with different fill factors.

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

    Science.gov (United States)

    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.

  4. Diffraction-grating neutron interferometers

    International Nuclear Information System (INIS)

    Ioffe, A.I.

    1988-01-01

    Aberration distortions of wavefronts in a very cold neutron interferometer using diffraction gratings are analyzed. Aberrations that considerably reduce the efficiency of a two-grating interferometer are shown to be fully compensable by adding a third diffraction grating, which also permits the interferometer to operate with a non-collimated and non-monochromatized illuminating beam thereby raising its efficiency. A fourth diffraction grating additionally permits compensation of effects of the terrestrial rotation that affect performance of a large interferometer in which the spatial separation of beams can be of the order of a few meters. It is demonstrated to be practically possible to implement an interferometer for neutrons having a wavelength λ = 20 A and to use it in experiments aimed at finding the electric charge of the neutron at the level of 10 -23 to 10 -22 of the electronic charge. (orig.)

  5. Encapsulation process for diffraction gratings.

    Science.gov (United States)

    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.

  6. Neutron interferometers with diffraction gratings

    International Nuclear Information System (INIS)

    Ioffe, A.I.

    1983-01-01

    A neutron interferometer is described in which the amplitude coherent division of the wave fronts is realized by means of neutron diffraction gratings. Photolithographic gratings on glass with a rectangular surface relief profile with a 58 Ni sprayed layer 2000 A thick are used as gratings. In contrast to perfect-crystal neutron interferometers the designed interferometer is capable of operating in the longwave neutron spectrum region. Variation of the value of spatial division of the interfering beams (up to 50 cm) and rather a high efficiency of the amergent beam together with the elemination of neutron beam passage through the interferometer coherent divosor material in such an interferometer permit to use it for solving problems of the solid-state physics and nuclear physics, for example, foA searching for the Yang Mills long-range field

  7. Undergraduate Experiment with Fractal Diffraction Gratings

    Science.gov (United States)

    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…

  8. Diffraction by m-bonacci gratings

    International Nuclear Information System (INIS)

    Monsoriu, Juan A; Giménez, Marcos H; Furlan, Walter D; Barreiro, Juan C; Saavedra, Genaro

    2015-01-01

    We present a simple diffraction experiment with m-bonacci gratings as a new interesting generalization of the Fibonacci ones. Diffraction by these non-conventional structures is proposed as a motivational strategy to introduce students to basic research activities. The Fraunhofer diffraction patterns are obtained with the standard equipment present in most undergraduate physics labs and are compared with those obtained with regular periodic gratings. We show that m-bonacci gratings produce discrete Fraunhofer patterns characterized by a set of diffraction peaks which positions are related to the concept of a generalized golden mean. A very good agreement is obtained between experimental and numerical results and the students’ feedback is discussed. (paper)

  9. Production of diffraction gratings using holographic interferometry

    International Nuclear Information System (INIS)

    Ecevit, F.N.; Guven, H.; Aydin, R.

    1989-09-01

    Holographic transmission gratings are produced using low power He-Ne laser and the 488-nm Ar-ion laser line. From the observed data of the Hg spectrum and the 488.0-nm, 514.5-nm and 632.8-nm laser lines the fringe spacings of the gratings are calculated. Using the gratings produced with the He-Ne laser the Rydberg constant is determined by measuring the diffraction angles of the Balmer series in the H-atomic spectrum. (author). 12 refs, 4 figs, 1 tab

  10. Blazed Grating Resonance Conditions and Diffraction Efficiency Optical Transfer Function

    KAUST Repository

    Stegenburgs, Edgars

    2017-01-08

    We introduce a general approach to study diffraction harmonics or resonances and resonance conditions for blazed reflecting gratings providing knowledge of fundamental diffraction pattern and qualitative understanding of predicting parameters for the most efficient diffraction.

  11. Nanostructure Diffraction Gratings for Integrated Spectroscopy and Sensing

    Science.gov (United States)

    Guo, Junpeng (Inventor)

    2016-01-01

    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. Low aberration monolithic diffraction gratings for high performance optical spectrometers

    Science.gov (United States)

    Triebel, Peter; Moeller, Tobias; Diehl, Torsten; Gatto, Alexandre; Pesch, Alexander; Erdmann, Lars E.; Burkhardt, Matthias; Kalies, Alexander

    2017-09-01

    Gratings are the core element of the spectrometer. For imaging spectrometers beside the polarization sensitivity and efficiency the imaging quality of the diffraction grating is essential. Lenses and mirrors can be produced with lowest wavefront aberrations. Low aberration imaging quality of the grating is required not to limit the overall imaging quality of the instrument. Different types of spectrometers will lead to different requirements on the wavefront aberrations for their specific diffraction gratings. The wavefront aberration of an optical grating is a combination of the substrate wavefront and the grating wavefront. During the manufacturing process of the grating substrate different processes can be applied in order to minimize the wavefront aberrations. The imaging performance of the grating is also optimized due to the recording setup of the holography. This technology of holographically manufactured gratings is used for transmission and reflection gratings on different types of substrates like prisms, convex and concave spherical and aspherical surface shapes, free-form elements. All the manufactured gratings are monolithic and can be coated with high reflection and anti-reflection coatings. Prism substrates were used to manufacture monolithic GRISM elements for the UV to IR spectral range preferably working in transmission. Besides of transmission gratings, numerous spectrometer setups (e.g. Offner, Rowland circle, Czerny-Turner system layout) working on the optical design principles of reflection gratings. The present approach can be applied to manufacture high quality reflection gratings for the EUV to the IR. In this paper we report our latest results on manufacturing lowest wavefront aberration gratings based on holographic processes in order to enable at least diffraction limited complex spectrometric setups over certain wavelength ranges. Beside the results of low aberration gratings the latest achievements on improving efficiency together with

  13. Neutron diffraction on a grating with monochromatic and polychromatic neutrons

    International Nuclear Information System (INIS)

    Baumann, J.; Kalus, J.

    1989-01-01

    Neutron diffraction experiments on a grating using monochromatic and polychromatic neutrons are described. The grating constant G was 60 μm. By the use of an achromatic system we were able to observe higher order diffraction maxima even with a wavelength spread of Δλ/λ=0.5. (orig.)

  14. Diffraction of very cold neutrons at phase gratings

    Science.gov (United States)

    Eder, Kurt; Gruber, Manfred; Zeilinger, Anton; Gähler, Roland; Mampe, Walter

    1991-06-01

    We report extensive experiments on the diffraction of very cold neutrons ( λ ≈ 100 Å) at large-area transmission phase gratings with grating constants d = 2 μm and d = 1 μm, respectively. The experimental results are compared with Fresnel-Kirchhoff calculations showing agreement in great detail. Using phase gratings it is possible to shift intensities between different diffraction orders, thus making them very useful for other neutron-optics experiments at low energies. Also, the excellent manufacturing precision of our transmission phase gratings meets the requirements for such experiments like very-cold-neutron interferometry.

  15. Diffraction of very cold neutrons at phase gratings

    International Nuclear Information System (INIS)

    Eder, K.; Gruber, M.; Zeilinger, A.; Gaehler, R.; Mampe, W.

    1991-01-01

    We report extensive experiments on the diffraction of very cold neutrons (λ ≅ 100A) at large-area transmission phase gratings with grating constants d=2μm and d=1μm, respectively. The experimental results are compared with Fresnel-Kirchhoff calculations showing agreement in great detail. Using phase gratings it is possible to shift intensities between different diffraction orders, thus making them very useful for other neutron-optics experiments at low energies. Also, the excellent manufacturing precision of our transmission phase gratings meets the requirements for such experiments like very-cold-neutron interferometry. (orig.)

  16. EUV properties of two diffraction gratings

    International Nuclear Information System (INIS)

    Cotton, D.; Chakrabarti, S.; Edelstein, J.; Pranke, J.; Christensen, A.B.

    1988-01-01

    The efficiency and scattering characteristics of a mechanically ruled grating (MRG) and a holographically ruled grating (HRG) are presented. One of these gratings will be employed in the Extreme Ultraviolet Spectrometer, an instrument of the Remote Atmospheric and Ionospheric Detector System to be flown aboard a TIROS satellite in 1991. The HRG showed much less Lyman alpha scattering, while the MRG had the better efficiency over most of the spectral range covered. 8 refs

  17. MEMS Tunable Diffraction Grating for Spaceborne Imaging Spectroscopic Applications

    Directory of Open Access Journals (Sweden)

    Sanathanan S. Muttikulangara

    2017-10-01

    Full Text Available Diffraction gratings are among the most commonly used optical elements in applications ranging from spectroscopy and metrology to lasers. Numerous methods have been adopted for the fabrication of gratings, including microelectromechanical system (MEMS fabrication which is by now mature and presents opportunities for tunable gratings through inclusion of an actuation mechanism. We have designed, modeled, fabricated and tested a silicon based pitch tunable diffraction grating (PTG with relatively large resolving power that could be deployed in a spaceborne imaging spectrometer, for example in a picosatellite. We have carried out a detailed analytical modeling of PTG, based on a mass spring system. The device has an effective fill factor of 52% and resolving power of 84. Tuning provided by electrostatic actuation results in a displacement of 2.7 μ m at 40 V . Further, we have carried out vibration testing of the fabricated structure to evaluate its feasibility for spaceborne instruments.

  18. Metallic diffraction grating enhanced coupling in whispering gallery resonator.

    Science.gov (United States)

    Zhou, Yanyan; Yu, Xia; Zhang, Haixi; Luan, Feng

    2013-04-08

    For the first time, metallic diffraction grating is investigated to enable efficient coupling in the whispering gallery resonator (WGR). Six-fold field enhancement in the resonator is achieved with respect to their dielectric counter-parts. This higher coupling efficiency is attributed to the surface plasmon excitation which drives the whispering gallery mode along the grating. Fano resonances have been observed in optical reflection. With the metallic grating, single-port end-fire WGR configuration becomes possible - a scheme that has not been demonstrated in any other WGR coupling devices. Hence, it serves as a prototype for portable whispering gallery devices potentially useful in sensing, switching and nonlinear applications.

  19. [Diffraction gratings used in x-ray spectroscopy]: Final report

    International Nuclear Information System (INIS)

    Smith, H.I.

    1988-01-01

    This subcontract was initiated in order to facilitate the development at MIT of technologies for fabricating the very fine diffraction grating required in x-ray spectroscopy at Lawrence Livermore Laboratory (LLL). These gratings are generally gold transmission gratings with spatial periods of 200 nm or less. The major focus of our efforts was to develop a means of fabricating gratings of 100 nm period. We explored two approaches: e-beam fabrication of x-ray lithography masks, and achromatic holographic lithography. This work was pursued by Erik Anderson as a major component of his Ph.D. thesis. Erik was successful in both the e-beam and holographic approaches. However, the e-beam method proved to be highly impractical: exposure times of about 115 days would be required to cover an area of 1 cm 2 . The achromatic holography, on the other hand, should be capable of exposing areas well in excess of 1 cm 2 in times under 1 hour. Moreover, 100 nm-period gratings produced by achromatic holography are coherent over their entire area whereas gratings produced by e-beam lithography are coherent only over areas /approximately/100 μm. The remainder of this report consists of portions excerpted from Erik Anderson's thesis. These contain all the details of our work on 100 nm period gratings. 26 refs., 17 figs

  20. Diffraction from relief gratings on a biomimetic elastomer cast

    International Nuclear Information System (INIS)

    Guerrero, Raphael A.; Aranas, Erika B.

    2010-01-01

    Biomimetic optical elements combine the optimized designs of nature with the versatility of materials engineering. We employ a beetle carapace as the template for fabricating relief gratings on an elastomer substrate. Biological surface features are successfully replicated by a direct casting procedure. Far-field diffraction effects are discussed in terms of the Fraunhofer approximation in Fourier space.

  1. Trapezoidal diffraction grating beam splitters in single crystal diamond

    Science.gov (United States)

    Kiss, Marcell; Graziosi, Teodoro; Quack, Niels

    2018-02-01

    Single Crystal Diamond has been recognized as a prime material for optical components in high power applications due to low absorption and high thermal conductivity. However, diamond microstructuring remains challenging. Here, we report on the fabrication and characterization of optical diffraction gratings exhibiting a symmetric trapezoidal profile etched into a single crystal diamond substrate. The optimized grating geometry diffracts the transmitted optical power into precisely defined proportions, performing as an effective beam splitter. We fabricate our gratings in commercially available single crystal CVD diamond plates (2.6mm x 2.6mm x 0.3mm). Using a sputter deposited hard mask and patterning by contact lithography, the diamond is etched in an inductively coupled oxygen plasma with zero platen power. The etch process effectively reveals the characteristic {111} diamond crystal planes, creating a precisely defined angled (54.7°) profile. SEM and AFM measurements of the fabricated gratings evidence the trapezoidal shape with a pitch of 3.82μm, depth of 170 nm and duty cycle of 35.5%. Optical characterization is performed in transmission using a 650nm laser source perpendicular to the sample. The recorded transmitted optical power as function of detector rotation angle shows a distribution of 21.1% in the 0th order and 23.6% in each +/-1st order (16.1% reflected, 16.6% in higher orders). To our knowledge, this is the first demonstration of diffraction gratings with trapezoidal profile in single crystal diamond. The fabrication process will enable beam splitter gratings of custom defined optical power distribution profiles, while antireflection coatings can increase the efficiency.

  2. Diffraction-analysis-based characterization of very fine gratings

    Science.gov (United States)

    Bischoff, Joerg; Truckenbrodt, Horst; Bauer, Joachim J.

    1997-09-01

    Fine gratings with spatial periods below one micron, either ruled mechanically or patterned holographically, play a key role as encoders in high precision translational or rotational coordinate or measuring machines. Besides, the fast in-line characterization of submicron patterns is a stringent demand in recent microelectronic technology. Thus, a rapid, destruction free and highly accurate measuring technique is required to ensure the quality during manufacturing and for final testing. We propose an optical method which was already successfully introduced in semiconductor industry. Here, the inverse scatter problem inherent in this diffraction based approach is overcome by sophisticated data analysis such as multivariate regression or neural networks. Shortly sketched, the procedure is as follows: certain diffraction efficiencies are measured with an optical angle resolved scatterometer and assigned to a number of profile parameters via data analysis (prediction). Before, the specific measuring model has to be calibrated. If the wavelength-to-period rate is well below unity, it is quite easy to gather enough diffraction orders. However, for gratings with spatial periods being smaller than the probing wavelength, merely the specular reflex will propagate for perpendicular incidence (zero order grating). Consequently, it is virtually impossible to perform a regression analysis. A proper mean to tackle this bottleneck is to record the zero-order reflex as a function of the incident angle. In this paper, the measurement of submicron gratings is discussed with the examples of 0.8, 1.0 and 1.4 micron period resist gratings on silicon, etched silicon oxide on silicon (same periods) and a 512 nm pitch chromium grating on quartz. Using a He-Ne laser with 633 nm wavelength and measuring the direct reflex in both linear polarizations, it is shown that even submicron patterning processes can be monitored and the resulting profiles with linewidths below a half micron can be

  3. Fresnel equations and transmission line analogues for diffraction gratings

    Energy Technology Data Exchange (ETDEWEB)

    Kaushik, S.

    1995-08-01

    A simple and intuitive formalism is presented to describe diffraction in multi-layered periodic structures. We use the well known results from scalar analysis (wave propagation in homogeneous layered media) and show that they can be generalized rather readily to vector problems such as diffraction analysis. Specifically, we derive: (1) generalized Fresnel equations appropriate for reflection and transmission from an infinitely thick grating, (2) a generalized Airy formula for thin-film to describe reflection and transmission of light through a lamellar grating and (3) a matrix propagation method akin to that used for multi-layer thin film analysis. The results developed here complement the recent work on R-matrix and S-matrix propagation algorithms that have been used in connection with modal and differential grating theories. These algorithms have proven to be numerically stable for calculating diffraction efficiencies from deep groove gratings. The formalism developed here expands upon the earlier literature by providing important details that are hitherto unavailable.

  4. The potential of diffraction grating for spatial applications

    Science.gov (United States)

    Jourlin, Y.; Parriaux, O.; Pigeon, F.; Tischenko, A. V.

    2017-11-01

    Diffraction gratings are know, and have been fabricated for more than one century. They are now making a come back for two reasons: first, because they are now better understood which leads to the efficient exploitation of what was then called their "anomalies"; secondly, because they are now fabricable by means of the modern manufacturing potential of planar technologies. Novel grating can now perform better than conventional gratings, and address new application fields which were not expected to be theirs. This is the case of spatial applications where they can offer multiple optical functions, low size, low weight and mechanical robustness. The proposed contribution will briefly discuss the use of gratings for spatial applications. One of the most important applications is in the measurement of displacement. Usual translation and rotation sensors are bulky devices, which impose a system breakdown leading to cumbersome and heavy assemblies. We are proposing a miniaturized version of the traditional moving grating technique using submicron gratings and a specific OptoASIC which enables the measurement function to be non-obtrusively inserted into light and compact electro-mechanical systems. Nanometer resolution is possible with no compromise on the length of the measurement range. Another family of spatial application is in the field of spectrometers where new grating types allow a more flexible processing of the optical spectrum. Another family of applications addresses the question of inter-satellite communications: the introduction of gratings in laser cavities or in the laser mirrors enables the stabilization of the emitted polarization, the stabilization of the frequency as well as wide range frequency sweeping without mobile parts.

  5. Beam focusing in reflections from flat subwavelength diffraction gratings

    OpenAIRE

    Cheng, Yu Chieh; Redondo, Javier; Staliunas, Kestutis

    2014-01-01

    We predict that narrow beams, reflecting from flat subwavelength diffraction gratings, can focus. The effect is shown for the beams of electromagnetic radiation; however, it should be observable for beams of waves of arbitrary nature (microwaves, surface plasmons, and acoustic and mechanical waves). We present analytical estimations of the focusing performance obtained by multiple scattering calculations and demonstrate the focusing effect numerically for an optical system (reflections from a...

  6. Diffraction of slow neutrons by holographic SiO2 nanoparticle-polymer composite gratings

    Science.gov (United States)

    Klepp, J.; Pruner, C.; Tomita, Y.; Plonka-Spehr, C.; Geltenbort, P.; Ivanov, S.; Manzin, G.; Andersen, K. H.; Kohlbrecher, J.; Ellabban, M. A.; Fally, M.

    2011-07-01

    Diffraction experiments with holographic gratings recorded in SiO2 nanoparticle-polymer composites have been carried out with slow neutrons. The influence of parameters such as nanoparticle concentration, grating thickness, and grating spacing on the neutron-optical properties of such materials has been tested. Decay of the grating structure along the sample depth due to disturbance of the recording process becomes an issue at grating thicknesses of about 100 microns and larger. This limits the achievable diffraction efficiency for neutrons. As a solution to this problem, the Pendellösung interference effect in holographic gratings has been exploited to reach a diffraction efficiency of 83% for very cold neutrons.

  7. Genetic algorithm-based design method for multilevel anisotropic diffraction gratings

    Science.gov (United States)

    Okamoto, Hiroyuki; Noda, Kohei; Sakamoto, Moritsugu; Sasaki, Tomoyuki; Wada, Yasuhiro; Kawatsuki, Nobuhiro; Ono, Hiroshi

    2017-08-01

    We developed a method for the design of multilevel anisotropic diffraction gratings based on a genetic algorithm. The method is used to design the multilevel anisotropic diffraction gratings based on input data that represent the output from the required grating. The validity of the proposed method was evaluated by designing a multilevel anisotropic diffraction grating using the outputs from an orthogonal circular polarization grating. The design results corresponded to the orthogonal circular polarization grating structures that were used to provide outputs to act as the input data for the process. Comparison with existing design methods shows that the proposed method can reduce the number of human processes that are required to design multilevel anisotropic diffraction gratings. Additionally, the method will be able to design complex structures without any requirement for subsequent examination by a human designer. The method can contribute to the development of optical elements by designing multilevel anisotropic diffraction gratings.

  8. High Resolving Power Volume Diffractive Gratings for 400-2700 nm Spectral Range, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The main purpose of this NASA SBIR Phase II proposal is development of a novel type of high resolving power diffraction gratings based on volume Bragg gratings...

  9. High Resolving Power Volume Diffractive Gratings for 400-2700 nm Spectral Range Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The purpose of this NASA SBIR Phase I proposal is to develop a novel type of high resolving power diffraction gratings based on volume Bragg gratings technology. The...

  10. Holographic binary grating liquid crystal cells fabricated by one-step exposure of photocrosslinkable polymer liquid crystalline alignment substrates to a polarization interference ultraviolet beam.

    Science.gov (United States)

    Kawai, Kotaro; Sasaki, Tomoyuki; Noda, Kohei; Sakamoto, Moritsugu; Kawatsuki, Nobuhiro; Ono, Hiroshi

    2015-07-01

    Holographic binary grating liquid crystal (LC) cells, in which the optical anisotropy was rectangularly modulated even as the grating was fabricated using holographic exposure, were fabricated by one-step polarization holographic exposure of an empty glass cell, the interior of which was coated with a photocrosslinkable polymer LC (PCLC). The present study is of great significance in that three types of holographic binary grating LC cells containing twisted alignments can be fabricated by simultaneous exposure of two PCLC substrates to the UV interference beams, which are sinusoidally modulated. The polarization conversion properties of the diffracted beams are explained well by theoretical analysis based on Jones calculus.

  11. Design of polarization-independent transmission fused-silica grating with high diffraction efficiency

    Science.gov (United States)

    Cheng, Yushui; Li, Chaoming; Chen, Xinrong; Yu, Jian; Tang, Yu; Wang, Rui; Xu, Haiyan; Hu, Zuyuan; Wu, Jianhong

    2018-01-01

    The high diffraction efficiency and high dispersion ability of diffraction grating plays a very important role in laser systems. Fused-silica transmission gratings not only have board band, high diffraction efficiency and high damage threshold, but also have the advantage of light path without shelter comparing to reflective gratings. In this paper, the study of polarization-independent transmission fused-silica grating is carried out, and the influence of rectangular and trapezoidal grating microstructures on the -1st diffraction efficiency of grating is analyzed. For trapezoidal groove structure, in the range of 80 to 90 degrees, the distributions of diffraction efficiency at different bottom angle are calculated and analyzed. The structure parameters of the grating are optimized by rigorous coupled wave theory. The designed grating groove density is 1440 lines/mm. The -1st diffraction efficiency of the grating is over 96% for both of TE and TM polarized waves at the Littrow angle (49.7 degrees) with the center wavelength of 1060nm. Within the bandwidth of 42nm (from 1039 to 1081nm), the -1st diffraction efficiency of the designed grating is theoretically greater than 90% for both of TE and TM polarized waves.

  12. Multiple Order Diffractions by laser-Injured Transient Grating in Nematic MBBA Film

    International Nuclear Information System (INIS)

    Kim, Seong Kyu; Kim, Hack Jin

    1999-01-01

    The laser-induced transient grating method is applied to study the dynamics of the nematic MBBA film. The nanosecond laser pulses of 355 nm are used to make the transient grating and the cw He-Ne laser of 633 nm is used to probe the dynamics. Strong multiple order diffractions are observed at high nematic temperatures. The reordering process induced by the phototransformed state, which is the locally melted state from the nematic sample, is attributed to the main origin of the multiple order diffractions from the nematic MBBA. The characteristics of the multiple order gratings are discussed with the grating profiles simulated from the multiple diffraction signals

  13. Calculation of duty cycle of beam sampling grating mask and analysis on diffraction efficiency uniformity of beam sampling grating

    Science.gov (United States)

    Xia, Xiaobin; Chen, Xinrong; Wu, Jianhong

    2011-11-01

    Cr mask is applied to fabricate beam sampling gratings (BSG) used in inertial confinement fusion (ICF). There are requirements on both first-order average diffraction efficiency and uniformity diffraction efficiency of BSG, so duty cycles of Cr mask grating must be measured to analyze the diffraction performance. The special Cr mask is one kind of grating with curved fringes and differing periods. In this paper, a method which can calculate duty cycles of Cr mask by measuring the zeroth-order diffraction efficiency is introduced. Based on rigorous coupled wave analysis (RCWA) theory, this method takes curved fringes as straight, and then calculates duty cycles under certain diffraction efficiencies by using the drawing of the change of diffraction efficiencies against the change of duty cycles and periods. A duty cycle can be found at a very diffraction efficiency and period. With duty cycles obtained, average diffraction efficiency and diffraction efficiency RMS can be calculated at certain etch depth. Also an example is given.

  14. Critical femtosecond laser parameters for the fabrication of optimal reflecting diffraction gratings on Invar36

    Science.gov (United States)

    Mohammad Hossein, Goudarzi; Meng-Jyun, Lin; Ji-Bin, Horng; Jeng-Ywan, Jeng

    2016-06-01

    This paper discusses the effect of femtosecond laser parameters on Invar36, and the efficiency of reflecting diffraction gratings on the alloy. Several gratings were made with different laser parameters in two regimes: constant repetition rates and constant average laser power on the Invar surface. The efficiency of diffraction gratings is measured in an off-plane configuration by determining the power of diffracted points. With the constant average power technique, an increase in laser influence decreased the ablation depth of lines and increased the line widths. The discoloration of line edges from increasing the laser influence more than 0.57 J /cm2 decreased the grating efficiency by over 49%. It was also found that increasing the repetition rate enhanced the grating efficiency and increasing the average power decreased the efficiency. In addition, the ablation threshold of Invar is 0.122 J /cm2 when the number of pulses (NOP) equals 389.

  15. A Simple Diffraction Experiment Using Banana Stem as a Natural Grating

    Science.gov (United States)

    Aji, Mahardika Prasetya; Karunawan, Jotti; Chasanah, Widyastuti Rochimatun; Nursuhud, Puji Iman; Wiguna, Pradita Ajeng; Sulhadi

    2017-01-01

    A simple diffraction experiment was designed using banana stem as natural grating. Coherent beams of lasers with wavelengths of 632.8 nm and 532 nm that pass through banana stem produce periodic diffraction patterns on a screen. The diffraction experiments were able to measure the distances between the slit of the banana stem, i.e. d = (28.76 ±…

  16. Diffraction efficiency of plasmonic gratings fabricated by electron beam lithography using a silver halide film

    Energy Technology Data Exchange (ETDEWEB)

    Sudheer,, E-mail: sudheer@rrcat.gov.in, E-mail: sudheer.rrcat@gmail.com; Tiwari, P.; Srivastava, Himanshu; Rai, V. N.; Srivastava, A. K.; Naik, P. A. [Homi Bhabha National Institute, Mumbai, Maharashtra 400094 (India); Indus Synchrotrons Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore, Madhya Pradesh 452013 (India); Porwal, S. [Solid State Lasers Division, Raja Ramanna Centre for Advanced Technology, Indore, Madhya Pradesh 452013 (India); Bhartiya, S. [Homi Bhabha National Institute, Mumbai, Maharashtra 400094 (India); Laser Materials Development and Device Division, Raja Ramanna Centre for Advanced Technology, Indore, Madhya Pradesh 452013 (India); Rao, B. T. [Homi Bhabha National Institute, Mumbai, Maharashtra 400094 (India); Laser Materials Processing Division, Raja Ramanna Centre for Advanced Technology, Indore, Madhya Pradesh 452013 (India); Sharma, T. K. [Homi Bhabha National Institute, Mumbai, Maharashtra 400094 (India); Solid State Lasers Division, Raja Ramanna Centre for Advanced Technology, Indore, Madhya Pradesh 452013 (India)

    2016-07-28

    The silver nanoparticle surface relief gratings of ∼10 μm period are fabricated using electron beam lithography on the silver halide film substrate. Morphological characterization of the gratings shows that the period, the shape, and the relief depth in the gratings are mainly dependent on the number of lines per frame, the spot size, and the accelerating voltage of electron beam raster in the SEM. Optical absorption of the silver nanoparticle gratings provides a broad localized surface plasmon resonance peak in the visible region, whereas the intensity of the peaks depends on the number density of silver nanoparticles in the gratings. The maximum efficiency of ∼7.2% for first order diffraction is observed for the grating fabricated at 15 keV. The efficiency is peaking at 560 nm with ∼380 nm bandwidth. The measured profiles of the diffraction efficiency for the gratings are found in close agreement with the Raman-Nath diffraction theory. This technique provides a simple and efficient method for the fabrication of plasmonic nanoparticle grating structures with high diffraction efficiency having broad wavelength tuning.

  17. Improved light harvest in diffraction grating-embedded TiO2 nanoparticle film

    Science.gov (United States)

    Lee, Jeeyoung; Lee, Myeongkyu

    2017-12-01

    We show that a high-efficiency diffraction grating can be embedded into nanoparticulate TiO2 film via imprinting combined with TiCl4 treatment. The grating-embedded film consists of two layers in intimate contact. A thin TiO2 layer was first patterned on a glass substrate by imprinting. The patterned layer was TiCl4-treated with a higher concentration than the over-coated thicker layer, so that it diffracts incident light as a refractive-index grating. Gratings with a period scaled down to 1 µm could be embedded into the film. Diffraction efficiency increased with an increasing grating height and an efficiency over 80% was achieved in the near-ultraviolet and visible range. Dye-sensitized solar cells fabricated using a grating-embedded TiO2 photoanode exhibited much better photovoltaic performance than those without a grating. It was also found that the incorporation of a diffraction grating greatly enhances the photocatalytic activity of nanoparticulate TiO2 film. All these are attributed to improved light harvest.

  18. System and technique for characterizing fluids using ultrasonic diffraction grating spectroscopy

    Science.gov (United States)

    Greenwood, Margaret S [Richland, WA

    2008-07-08

    A system for determining property of multiphase fluids based on ultrasonic diffraction grating spectroscopy includes a diffraction grating on a solid in contact with the fluid. An interrogation device delivers ultrasound through the solid and a captures a reflection spectrum from the diffraction grating. The reflection spectrum exhibits peaks whose relative size depends on the properties of the various phases of the multiphase fluid. For example, for particles in a liquid, the peaks exhibit dependence on the particle size and the particle volume fraction. Where the exact relationship is know know a priori, data from different peaks of the same reflection spectrum or data from the peaks of different spectra obtained from different diffraction gratings can be used to resolve the size and volume fraction.

  19. Diffraction characteristics of spatial and temporal Gaussian-shaped femtosecond laser pulse by rectangle reflection grating.

    Science.gov (United States)

    Liu, Guohua; Xu, Rongrong; Yu, Wenbing; Wu, Hanping

    2011-02-20

    The exact intensity distribution expression for the spatial and temporal Gaussian-shaped femtosecond laser pulse diffracted by a rectangle reflection grating is derived. The spatial and temporal diffraction characteristics are theoretically investigated in detail, and a criterion for judging whether or not the diffraction pulse is just split into two independent pulses in the temporal domain is obtained. The results show that the diffraction intensity in the temporal domain consists of three parts: the intensity diffracted by the upper reflection surface of the grating, the intensity diffracted by the nether reflection surface, and their temporal coherent intensity. The temporal coherent intensity becomes weaker, even is zero, for the higher height from the nether surface to the upper surface of the grating. The principal maximum becomes more sharply bright for the bigger waist width of the femtosecond laser pulse in the spatial domain.

  20. Analysis of near-field of diffractive gratings used in inertial confinement fusion driver

    Science.gov (United States)

    Tang, Xionggui; Gao, Fuhua; Gao, Feng; Zhang, Yixiao; Du, Jinglei; Guo, Yongkang; Du, Chunlei

    2005-02-01

    Diffractive gratings, such as 1 grating and beam sampling grating (BSG), are used in the inertial confinement fusion (ICF) driver because of their high diffractive efficiency. Under high power laser condition, it demands that near fields of the diffractive gratings, mainly affected by input laser energy and beam modulation, must be less than their damage threshold, otherwise the diffractive gratings will be damaged. In this paper, Fourier modal method based on the rigorous electromagnetic theory is introduced to rapidly and accurately analyze the distribution of near fields of the diffractive gratings. Its physical concept is clear and concise, and computation cost is small. Through numerical simulation, it indicates that the results calculated by Fourier modal method are accurate and effective, compared with those calculated by other method. The near fields of 1 grating used in final optical system of ICF driver are obtained. In addition, fabrication errors effects on the near field modulation are simulated. It shows that the sidewall slope errors are the main cause of optical field modulation. With theoretical analysis and numerical simulation, it is useful to understand mechanism of damage and help how to control fabrication process errors of the optical elements used in the optical system of ICF.

  1. Ruled and holographic diffraction gratings experiment (AO 138-5)

    Science.gov (United States)

    Bonnemason, Francis

    1992-01-01

    Ruled and Holographic Gratings (originals and replicas) proposed for use in loaded spectroscopic experiments are discussed. The optical performance of the gratings was tested in the low-earth orbital environment. Comparisons were made with identical components, which had been stored on the earth for the duration of the experiment. The following tests were performed: wavefront planeity, light efficiency, and stray-light level.

  2. Direct fabrication of diffraction grating onto organic single crystals by electron beam lithography

    Science.gov (United States)

    Kawata, Yoshihiro; Aoki, Kazuki; Inada, Yuhi; Yamao, Takeshi; Hotta, Shu

    2018-03-01

    We have directly fabricated a diffraction grating onto platelike single crystals made of an organic semiconducting oligomer by electron beam lithography followed by reactive-ion etching. The decrease in the grating period resulted in photoexcited spectrally narrowed emission peaks related to the first-order diffraction from the crystal edge without outstanding quenching of the crystal. This work is expected to lead to the realization of organic semiconductor lasers.

  3. Changes in diffraction efficiency of gratings with high fructose corn syrup by aging

    Science.gov (United States)

    Mejias-Brizuela, Nildia Y.; Olivares-Pérez, Arturo

    2017-03-01

    High fructose corn syrup was used for preparation of holographic gratings photosensitized with potassium bichromated, for to analyze the behavior of diffraction efficiency to first order. The behavior of diffraction efficiency to first order was analyzed at time intervals different: 24, 48, 72 and 96 hours, because to the recorded gratings showed instability 24 hours after of record. For this reason, we decided to study in the time the evolution of diffraction efficiency parameter for to determine the maximum modulation of material holographic (HFCS-bichromated). The study realized showed that after of 72 hours, the photosensitized material reaches its maximum modulation, with a diffraction efficiency to first order of 4 percent.

  4. Enhanced diffraction properties of photoinduced gratings in nematic liquid crystals doped with Disperse Red 1.

    Science.gov (United States)

    Li, Hongjing; Wang, Jianhao; Wang, Changshun; Zeng, Pengfei; Pan, Yujia; Yang, Yifei

    2016-01-01

    Diffraction properties of photoinduced gratings recorded by overlapping two coherent beams at 532 nm in nematic liquid crystals doped with Disperse Red 1 were investigated with a probe beam at 632.8 nm. The grating was formed due to the alignment of dye molecules that leaded to the reorientation of the liquid crystal phase. The diffraction efficiency of the photoinduced grating was found to increase rapidly when the sample temperature was close to the clearing point in the nematic phase and a nearly 30-fold enhancement of the first-order diffraction efficiency was obtained. The pretransitional enhancement of the diffraction efficiency was discussed in terms of the reorientation of liquid crystals, optical nonlinearity effects and the onset of critical opalescence near the nematic-isotropic phase transition. Moreover, a peak shift of diffraction efficiency towards the lower temperature was observed with the increase of recording light intensity, which was attributed to laser induced photochemical disordering.

  5. Analytic theory of soft x-ray diffraction by lamellar multilayer gratings

    NARCIS (Netherlands)

    Kozhevnikov, I.V.; van der Meer, R.; Bastiaens, Hubertus M.J.; Boller, Klaus J.; Bijkerk, Frederik

    2011-01-01

    An analytic theory describing soft x-ray diffraction by Lamellar Multilayer Gratings (LMG) has been developed. The theory is derived from a coupled waves approach for LMGs operating in the single-order regime, where an incident plane wave can only excite a single diffraction order. The results from

  6. Production Technology of Holographic Diffraction Gratings Based on Inorganic Vacuum Photoresists

    Directory of Open Access Journals (Sweden)

    Dan’ko, V.A.

    2014-09-01

    Full Text Available An innovative project on development of the technological method for holographic diffraction gratings production which allows to produce high-quality diffractive elements with spatial frequencies from 600 to 3600 mm–1 for spectral instruments have been carried out. The technological instructions for the implementation of this method have been developed and experimental samples are produced. It was established that the characteristics of experimental samples of the holographic diffraction gratings produced under this project meet the specifications and the state standard 3-6128-86.

  7. High-Average-Power Diffraction Pulse-Compression Gratings Enabling Next-Generation Ultrafast Laser Systems

    Energy Technology Data Exchange (ETDEWEB)

    Alessi, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-11-01

    Pulse compressors for ultrafast lasers have been identified as a technology gap in the push towards high peak power systems with high average powers for industrial and scientific applications. Gratings for ultrashort (sub-150fs) pulse compressors are metallic and can absorb a significant percentage of laser energy resulting in up to 40% loss as well as thermal issues which degrade on-target performance. We have developed a next generation gold grating technology which we have scaled to the petawatt-size. This resulted in improvements in efficiency, uniformity and processing as compared to previous substrate etched gratings for high average power. This new design has a deposited dielectric material for the grating ridge rather than etching directly into the glass substrate. It has been observed that average powers as low as 1W in a compressor can cause distortions in the on-target beam. We have developed and tested a method of actively cooling diffraction gratings which, in the case of gold gratings, can support a petawatt peak power laser with up to 600W average power. We demonstrated thermo-mechanical modeling of a grating in its use environment and benchmarked with experimental measurement. Multilayer dielectric (MLD) gratings are not yet used for these high peak power, ultrashort pulse durations due to their design challenges. We have designed and fabricated broad bandwidth, low dispersion MLD gratings suitable for delivering 30 fs pulses at high average power. This new grating design requires the use of a novel Out Of Plane (OOP) compressor, which we have modeled, designed, built and tested. This prototype compressor yielded a transmission of 90% for a pulse with 45 nm bandwidth, and free of spatial and angular chirp. In order to evaluate gratings and compressors built in this project we have commissioned a joule-class ultrafast Ti:Sapphire laser system. Combining the grating cooling and MLD technologies developed here could enable petawatt laser systems to

  8. Active cooling of pulse compression diffraction gratings for high energy, high average power ultrafast lasers.

    Science.gov (United States)

    Alessi, David A; Rosso, Paul A; Nguyen, Hoang T; Aasen, Michael D; Britten, Jerald A; Haefner, Constantin

    2016-12-26

    Laser energy absorption and subsequent heat removal from diffraction gratings in chirped pulse compressors poses a significant challenge in high repetition rate, high peak power laser development. In order to understand the average power limitations, we have modeled the time-resolved thermo-mechanical properties of current and advanced diffraction gratings. We have also developed and demonstrated a technique of actively cooling Petawatt scale, gold compressor gratings to operate at 600W of average power - a 15x increase over the highest average power petawatt laser currently in operation. Combining this technique with low absorption multilayer dielectric gratings developed in our group would enable pulse compressors for petawatt peak power lasers operating at average powers well above 40kW.

  9. Space applications: monolithic diffraction grating elements from EUV to NIR spectral range

    Science.gov (United States)

    Gatto, Alexandre; Pesch, Alexander; Erdmann, Lars H.; Burkhardt, Matthias; Kalies, Alexander; Diehl, Torsten; Triebel, Peter; Moeller, Tobias

    2017-11-01

    Monolithic diffraction gratings are one of the key components of high sensitive spectral imaging systems including spectrometer used in space instruments. These gratings are optimized for high efficiency, lowest line spacing errors and low scattering values to improve the performance of a spectral imaging system. Spectral imaging systems lead to enhanced remote sensing properties when the sensing system provides sufficient spectral resolution to identify materials from its spectral reflectance signature comprising low signal-to-noise ratios.

  10. Frequency Tuning of IR First-Overtone CO Laser Radiation by Diffraction Grating and Frequency Selective Output Couplers

    National Research Council Canada - National Science Library

    Ionin, Andre

    1999-01-01

    ...: The contractor will investigate, both experimentally and theoretically, the feasibility of frequency tuning the first overtone carbon monoxide laser radiation by the use of diffraction gratings...

  11. Enhanced monolithic diffraction gratings with high efficiency and reduced polarization sensitivity for remote sensing applications

    Science.gov (United States)

    Triebel, Peter; Diehl, Torsten; Moeller, Tobias; Gatto, Alexandre; Pesch, Alexander; Erdmann, Lars H.; Burkhardt, Matthias; Kalies, Alexander

    2015-10-01

    Spectral imaging systems lead to enhanced sensing properties when the sensing system provides sufficient spectral resolution to identify materials from its spectral reflectance signature. The performance of diffraction gratings provides an initial way to improve instrumental resolution. Thus, subsequent manufacturing techniques of high quality gratings are essential to significantly improve the spectral performance. The ZEISS unique technology of manufacturing real-blazed profiles and as well as lamellar profiles comprising transparent substrates is well suited for the production of transmission gratings. In order to reduce high order aberrations, aspherical and free-form surfaces can be alternatively processed to allow more degrees of freedom in the optical design of spectroscopic instruments with less optical elements and therefore size and weight advantages. Prism substrates were used to manufacture monolithic GRISM elements for UV to IR spectral range. Many years of expertise in the research and development of optical coatings enable high transmission anti-reflection coatings from the DUV to the NIR. ZEISS has developed specially adapted coating processes (Ion beam sputtering, ion-assisted deposition and so on) for maintaining the micro-structure of blazed gratings in particular. Besides of transmission gratings, numerous spectrometer setups (e.g. Offner, Rowland circle, Czerny-Turner system layout) working on the optical design principles of reflection gratings. This technology steps can be applied to manufacture high quality reflection gratings from the EUV to the IR applications with an outstanding level of low stray light and ghost diffraction order by employing a combination of holography and reactive ion beam etching together with the in-house coating capabilities. We report on results of transmission gratings on plane and curved substrates and GRISM elements with enhanced efficiency of the grating itself combined with low scattered light in the angular

  12. High-Density Diffraction Imaging and Non-Imaging Grating Elements for EUV and X-ray Spectroscopy Fabricated by DUV Reduction Photolithography, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Diffraction gratings are powerful tools for the spectral analysis of electromagnetic radiation. Properties of gratings are determined by available fabrication means...

  13. High diffraction efficiency polarization gratings recorded by biphotonic holography in an azobenzene liquid crystalline polyester

    DEFF Research Database (Denmark)

    Sánchez, C; Alcalá, R; Hvilsted, Søren

    2001-01-01

    High diffraction efficiencies have been achieved with polarization gratings recorded in thin films of an azobenzene side-chain liquid crystalline polyester by means of biphotonic processes. Efficiency values up to 30% have been reached after an induction period of 300 s and subsequent evolution...... with the sample in darkness. These values are at least two orders of magnitude higher than those previously reported for biphotonic recording. The gratings can be erased with unpolarized blue light and partial recovery of the diffraction efficiency has been observed after the erasure process when the sample...... is kept in darkness. Red light illumination of the erased film increases the recovered efficiency value and the recovery rate....

  14. Optical double-image cryptography based on diffractive imaging with a laterally-translated phase grating.

    Science.gov (United States)

    Chen, Wen; Chen, Xudong; Sheppard, Colin J R

    2011-10-10

    In this paper, we propose a method using structured-illumination-based diffractive imaging with a laterally-translated phase grating for optical double-image cryptography. An optical cryptosystem is designed, and multiple random phase-only masks are placed in the optical path. When a phase grating is laterally translated just before the plaintexts, several diffraction intensity patterns (i.e., ciphertexts) can be correspondingly obtained. During image decryption, an iterative retrieval algorithm is developed to extract plaintexts from the ciphertexts. In addition, security and advantages of the proposed method are analyzed. Feasibility and effectiveness of the proposed method are demonstrated by numerical simulation results. © 2011 Optical Society of America

  15. The application of diffraction grating in the design of virtual reality (VR) system

    Science.gov (United States)

    Chen, Jiekang; Huang, Qitai; Guan, Min

    2017-10-01

    Virtual Reality (VR) products serve for human eyes ultimately, and the optical properties of VR optical systems must be consistent with the characteristic of human eyes. The monocular coaxial VR optical system is simulated in ZEMAX. A diffraction grating is added to the optical surface next to the eye, and the lights emitted from the diffraction grating are deflected, which can forming an asymmetrical field of view(FOV). Then the lateral chromatic aberration caused by the diffraction grating was corrected by the chromatic dispersion of the prism. Finally, the aspheric surface was added to further optimum design. During the optical design of the system, how to balance the dispersion of the diffraction grating and the prism is the main problem. The balance was achieved by adjusting the parameters of the grating and the prism constantly, and then using aspheric surfaces finally. In order to make the asymmetric FOV of the system consistent with the angle of the visual axis, and to ensure the stereo vision area clear, the smaller half FOV of monocular system is required to reach 30°. Eventually, a system with asymmetrical FOV of 30°+40° was designed. In addition, the aberration curve of the system was analyzed by ZEMAX, and the binocular FOV was calculated according to the principle of binocular overlap. The results show that the asymmetry of FOV of VR monocular optical system can fit to human eyes and the imaging quality match for the human visual characteristics. At the same time, the diffraction grating increases binocular FOV, which decreases the requirement for the design FOV of monocular system.

  16. Multipitched Diffraction Gratings for Surface Plasmon Resonance-Enhanced Infrared Reflection Absorption Spectroscopy.

    Science.gov (United States)

    Petefish, Joseph W; Hillier, Andrew C

    2015-11-03

    We demonstrate the application of metal-coated diffraction gratings possessing multiple simultaneous pitch values for surface enhanced infrared absorption (SEIRA) spectroscopy. SEIRA increases the magnitude of vibrational signals in infrared measurements by one of several mechanisms, most frequently involving the enhanced electric field associated with surface plasmon resonance (SPR). While the majority of SEIRA applications to date have employed nanoparticle-based plasmonic systems, recent advances have shown how various metals and structures lead to similar signal enhancement. Recently, diffraction grating couplers have been demonstrated as a highly tunable platform for SEIRA. Indeed, gratings are an experimentally advantageous platform due to the inherently tunable nature of surface plasmon excitation at these surfaces since both the grating pitch and incident angle can be used to modify the spectral location of the plasmon resonance. In this work, we use laser interference lithography (LIL) to fabricate gratings possessing multiple pitch values by subjecting photoresist-coated glass slides to repetitive exposures at varying orientations. After metal coating, these gratings produced multiple, simultaneous plasmon peaks associated with the multipitched surface, as identified by infrared reflectance measurements. These plasmon peaks could then be coupled to vibrational modes in thin films to provide localized enhancement of infrared signals. We demonstrate the flexibility and tunability of this platform for signal enhancement. It is anticipated that, with further refinement, this approach might be used as a general platform for broadband enhancement of infrared spectroscopy.

  17. The infrared imaging spectrograph (IRIS) for TMT: reflective ruled diffraction grating performance testing and discussion

    Science.gov (United States)

    Meyer, Elliot; Chen, Shaojie; Wright, Shelley A.; Moore, Anna M.; Larkin, James E.; Simard, Luc; Marie, Jerome; Mieda, Etsuko; Gordon, Jacob

    2014-07-01

    We present the efficiency of near-infrared reflective ruled diffraction gratings designed for the InfraRed Imaging Spectrograph (IRIS). IRIS is a first light, integral field spectrograph and imager for the Thirty Meter Telescope (TMT) and narrow field infrared adaptive optics system (NFIRAOS). IRIS will operate across the near-infrared encompassing the ZYJHK bands (~0.84 - 2.4μm) with multiple spectral resolutions. We present our experimental setup and analysis of the efficiency of selected reflective diffraction gratings. These measurements are used as a comparison sample against selected candidate Volume Phase Holographic (VPH) gratings (see Chen et al., this conference). We investigate the efficiencies of five ruled gratings designed for IRIS from two separate vendors. Three of the gratings accept a bandpass of 1.19-1.37μm (J band) with ideal spectral resolutions of R=4000 and R=8000, groove densities of 249 and 516 lines/mm, and blaze angles of 9.86° and 20.54° respectively. The other two gratings accept a bandpass of 1.51-1.82μm (H Band) with an ideal spectral resolution of R=4000, groove density of 141 lines/mm, and blaze angle of 9.86°. The fraction of flux in each diffraction mode was compared to both a pure reflection mirror as well as the sum of the flux measured in all observable modes. We measure the efficiencies off blaze angle for all gratings and the efficiencies between the polarization transverse magnetic (TM) and transverse electric (TE) states. The peak reflective efficiencies are 98.90 +/- 3.36% (TM) and 84.99 +/- 2.74% (TM) for the H-band R=4000 and J-band R=4000 respectively. The peak reflective efficiency for the J-band R=8000 grating is 78.78 +/- 2.54% (TE). We find that these ruled gratings do not exhibit a wide dependency on incident angle within +/-3°. Our best-manufactured gratings were found to exhibit a dependency on the polarization state of the incident beam with a ~10-20% deviation, consistent with the theoretical efficiency

  18. High efficiency diffractive grating coupler based on transferred silicon nanomembrane overlay on photonic waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Saha, Tapas Kumar; Zhou Weidong [University of Texas at Arlington, Department of Electrical Engineering, NanoFAB Center, Arlington, TX 76019-0072 (United States)

    2009-04-21

    We report here the design of a new type of high efficiency grating coupler, based on single crystalline Si nanomembrane overlay and stacking. Such high efficiency diffractive grating couplers are designed for the purpose of coupling light between single mode fibres and nanophotonic waveguides, and for the coupling between multiple photonic interconnect layers for compact three-dimensional vertical integration. Two-dimensional model simulation based on eigenmode expansion shows a diffractive power-up efficiency of 81% and a fibre coupling efficiency of 64%. With nanomembrane stacking, it is feasible to integrate the side-distributed Bragg reflector and bottom reflector, which can lead to the diffractive power-up efficiency and the fibre coupling efficiency of 97% and 73.5%, respectively. For a negatively detuned coupler, the bottom reflector is not needed, and the diffractive power-up efficiency can reach 98% over a large spectral range. The device is extremely tolerant to fabrication errors.

  19. Diffracted wavefront measurement of a volume phase holographic grating at cryogenic temperature

    International Nuclear Information System (INIS)

    Blanche, Pierre-Alexandre; Habraken, Serge; Lemaire, Philippe; Jamar, Claude

    2006-01-01

    Flatness of the wavefront diffracted by grating can be mandatory for some applications. At ambient temperature, the wavefront diffracted by a volume phase holographic grating (VPHG) is well mastered by the manufacturing process and can be corrected or shaped by post polishing. However, to be used in cooled infrared spectrometers, VPHGs have to stand and work properly at low temperatures.We present the measurement of the wavefront diffracted by atypical VPHG at various temperatures down to 150 K and at several thermal inhomogeneity amplitudes. The particular grating observed was produced using a dichromated gelatine technique and encapsulated between two glass blanks. Diffracted wavefront measurements show that the wavefront is extremely stable according to the temperature as long as the latter is homogeneous over the grating stack volume. Increasing the thermal inhomogeneity increases the wavefront error that pinpoints the importance of the final instrument thermal design. This concludes the dichromated gelatine VPHG technology, used more and more in visible spectrometers, can be applied as it is to cooled IR spectrometers

  20. Complex method for angular-spectral analysis of volume phase diffraction gratings recorded in photopolymers

    Czech Academy of Sciences Publication Activity Database

    Vojtíšek, Petr; Květoň, M.; Richter, I.

    2016-01-01

    Roč. 11, February (2016), č. článku 16009. ISSN 1990-2573 R&D Projects: GA MŠk(CZ) LO1206 Institutional support: RVO:61389021 Keywords : Photopolymers * diffraction gratings * angular-spectral maps * spectral selectivity * angular selectivity Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.975, year: 2016

  1. Field lens multiplexing in holographic 3D displays by using Bragg diffraction based volume gratings

    Science.gov (United States)

    Fütterer, G.

    2016-11-01

    Applications, which can profit from holographic 3D displays, are the visualization of 3D data, computer-integrated manufacturing, 3D teleconferencing and mobile infotainment. However, one problem of holographic 3D displays, which are e.g. based on space bandwidth limited reconstruction of wave segments, is to realize a small form factor. Another problem is to provide a reasonable large volume for the user placement, which means to provide an acceptable freedom of movement. Both problems should be solved without decreasing the image quality of virtual and real object points, which are generated within the 3D display volume. A diffractive optical design using thick hologram gratings, which can be referred to as Bragg diffraction based volume gratings, can provide a small form factor and high definition natural viewing experience of 3D objects. A large collimated wave can be provided by an anamorphic backlight unit. The complex valued spatial light modulator add local curvatures to the wave field he is illuminated with. The modulated wave field is focused onto to the user plane by using a volume grating based field lens. Active type liquid crystal gratings provide 1D fine tracking of approximately +/- 8° deg. Diffractive multiplex has to be implemented for each color and for a set of focus functions providing coarse tracking. Boundary conditions of the diffractive multiplexing are explained. This is done in regards to the display layout and by using the coupled wave theory (CWT). Aspects of diffractive cross talk and its suppression will be discussed including longitudinal apodized volume gratings.

  2. Development of an ultra-high resolution diffraction grating forsoft x-rays

    Energy Technology Data Exchange (ETDEWEB)

    Voronov, Dmitriy L.; Cambie, Rossana; Feshchenko, Ruslan M.; Gullikson, Eric M.; Padmore, Howard A.; Vinogradov, Alexander V.; Yashchuk, Valeriy V.

    2007-08-21

    Resonant Inelastic X-ray Scattering (RIXS) is the one of themost powerful methods for investigation of the electronic structure ofmaterials, specifically of excitations in correlated electron systems.However the potential of the RIXS technique has not been fully exploitedbecause conventional grating spectrometers have not been capable ofachieving the extreme resolving powers that RIXS can utilize. State ofthe art spectrometers in the soft x-ray energy range achieve ~;0.25 eVresolution, compared to the energy scales of soft excitations andsuperconducting gap openings down to a few meV. Development ofdiffraction gratings with super high resolving power is necessary tosolve this problem. In this paper we study the possibilities offabrication of gratings of resolving power of up to 106 for the 0.5 1.5KeV energy range. This energy range corresponds to all or most of theuseful dipole transitions for elements of interest in most correlatedelectronic systems, i.e., oxygen K-edge of relevance to all oxides, thetransition metal L2,3 edges, and the M4,5 edges of the rare earths.Various approaches based on different kinds of diffraction gratings suchas deep-etched multilayer gratings, and multilayer coated echelettes arediscussed. We also present simulations of diffraction efficiency for suchgratings, and investigate the necessary fabricationtolerances.

  3. Optimizing a Cleaning Process for Multilayer-Dielectric- (MLD) Diffraction Grating

    International Nuclear Information System (INIS)

    Ashe, B.; Giacofei, C.; Myhre, G.; Schmid, A.W.

    2008-01-01

    A critical component for the OMEGA EP short-pulse petawatt laser system is the grating compressor chamber. This large vacuum chamber contains critical optics where laser-pulse compression is performed at the output of the system on two 40 cm-sq-aperture, IR (1054-nm) laser beams. Critical to this compression, within the grating compressor chamber, are four sets of tiled multilayer-dielectric-diffraction gratings that provide the capability for producing 2.6-kJ output IR energy per beam at 10 ps. Degradation of the grating laser-damage threshold due to adsorption of contaminants from the manufacturing process must be prevented to maintain system performance. In this paper we discuss an optimized cleaning process to achieve the OMEGA EP requirements. The fabrication of multilayer-dielectric gratings involves processes that utilize a wide variety of both organic materials (photoresist processes) and inorganic materials (metals and metal oxides) that can affect the final cleaning process. A number of these materials have significant optical absorbance; therefore, incomplete cleaning of these residues may result in the multilayer-dielectric gratings experiencing laser damage

  4. Conducting polymer diffraction gratings on gold surfaces created by microcontact printing and electropolymerization at submicron length scales.

    Science.gov (United States)

    Marikkar, F Saneeha; Carter, Chet; Kieltyka, Kathy; Robertson, Joseph W F; Williamson, Cathie; Simmonds, Adam; Zangmeister, Rebecca; Fritz, Torsten; Armstrong, Neal R

    2007-09-25

    Conducting polymer diffraction gratings on Au substrates have been created using microcontact printing of C18-alkanethiols, followed by electropolymerization of either poly(aniline) (PANI) or poly(3,4-ethylenedioxythiophene) (PEDOT). Soft-polymer replicas of simple diffraction grating masters (1200 lines/mm) were used to define the alkanethiol template for polymer growth. Growth of PANI and PEDOT diffraction gratings was followed in real time, through in situ tapping-mode atomic force microscopy, and by monitoring diffraction efficiency (DE) as a function of grating depth. DE increased as grating depth increased, up to a limiting efficiency (13-26%, with white light illumination), defined by the combined optical properties of the grating and the Au substrate, and ultimately limited by the loss of resolution due to coalescence of the polymer films. Grating efficiency is strongly dependent upon the grating depth and the refractive index contrast between the grating material and the surrounding solutions. Both PEDOT and PANI gratings show refractive index changes as a function of applied potential, consistent with changes in refractive index brought about by the doping/dedoping of the conducting polymer. The DE of PANI gratings are strongly dependent on the pH of the superstrate solution; the maximum sensitivity (DeltaDE/DeltapH) is achieved with PANI gratings held at +0.4 V versus Ag/AgCl, where the redox chemistry is dominated by the acid-base equilibrium between the protonated (emeraldine salt) and deprotonated (emeraldine base) forms of PANI. Simulations of DE were conducted for various combinations of conducting polymer refractive index and grating depth, to compute sensitivity parameters, which are maximized when the grating depth is ca. 50% of its maximum obtainable depth.

  5. Nanometer-scale displacement sensor based on phase-sensitive diffraction grating.

    Science.gov (United States)

    Zhao, Shuangshuang; Hou, Changlun; Bai, Jian; Yang, Guoguang; Tian, Feng

    2011-04-01

    In this paper, a nanometer-scale displacement sensor based on a phase-sensitive diffraction grating with interferometeric detection is described and experimentally demonstrated. The proposed displacement sensor consists of a coherent light source, a microstepping motor controller, an integrated grating, a mirror, and a differential circuit. Experimental results show that the displacement sensor has a sensitivity of about 6 mV/nm and a resolution of less than 1 nm. This displacement measurement is an attractive technology with high sensitivity, broad dynamic range, good reliability, and immunity to electromagnetic interference. © 2011 Optical Society of America

  6. High diffraction efficiency polarization gratings recorded by biphotonic holography in an azobenzene liquid crystalline polyester

    International Nuclear Information System (INIS)

    Sanchez, C.; Alcala, R.; Hvilsted, S.; Ramanujam, P. S.

    2001-01-01

    High diffraction efficiencies have been achieved with polarization gratings recorded in thin films of an azobenzene side-chain liquid crystalline polyester by means of biphotonic processes. Efficiency values up to 30% have been reached after an induction period of 300 s and subsequent evolution with the sample in darkness. These values are at least two orders of magnitude higher than those previously reported for biphotonic recording. The gratings can be erased with unpolarized blue light and partial recovery of the diffraction efficiency has been observed after the erasure process when the sample is kept in darkness. Red light illumination of the erased film increases the recovered efficiency value and the recovery rate. [copyright] 2001 American Institute of Physics

  7. Study of holographic diffraction gratings implemented in photopolymerizable glasses incorporating ionic liquid

    Science.gov (United States)

    Velasco, A. V.; Hernández-Garay, M. P.; Calvo, M. L.; Cheben, P.; del Monte, F.

    2011-05-01

    In this work we analyze the optical quality, performance, and recording mechanism of holographic diffraction gratings recorded in photopolymerizable sol-gel glasses. These classes of holographic photomaterials have various compositions, one of which incorporates a High Refractive Index Species (HRIS), already developed in our group GICO-UCM. The new types of photopolymerizable glasses under study incorporate ionic liquid (IL). We present a comparative study, showing distinctive behaviors for each photopolymerizable glass class, and determining particular features for various ranges of applications.

  8. Diffraction characteristics of chirped femtosecond laser pulse by rectangle reflection grating

    Science.gov (United States)

    Liu, Guohua; Xu, Rongrong; Wu, Hanping; Yu, Wenbing

    2012-06-01

    The spectral and temporal intensity distribution expression for the chirped femtosecond laser pulse diffracted by a rectangle reflection grating is derived. The effects of the chirped coefficient on the spatiotemporal and spectral characteristics are theoretically investigated in detail, and a criterion for judging whether or not the diffraction pulse is just split into two independent pulses in the temporal domain is obtained. The results show that the envelope curve of spectral intensity on the diffraction axis is more blue-shift, and its full width at e- 1 maximum is wider for bigger chirped coefficient. The principal maximum on the temporal axis can split into two independent principal maximums for enough height from the upper and the nether reflection surface of the grating. Each principal maximum splits into two smooth pulses, namely one principal pulse and one secondary pulse, and the secondary pulse gradually increases with the increasing of the chirped coefficient; the duration of two principal pulses increases with the increasing of the height of the upper and the nether reflection surface of the grating.

  9. PiC code KARAT simulations of Coherent THz Smith-Purcell Radiation from diffraction gratings of various profiles

    International Nuclear Information System (INIS)

    Artyomov, K P; Ryzhov, V V; Potylitsyn, A P; Sukhikh, L G

    2017-01-01

    Generation of coherent THz Smith-Purcell radiation by single electron bunch or multi-bunched electron beam was simulated for lamellar, sinusoidal and echelette gratings. The dependences of the CSPR intensity of the corrugation gratings depth were investigated. The angular and spectral characteristics of the CSPR for different profiles of diffraction gratings were obtained. It is shown that in the case of femtosecond multi-bunched electron beam with 10 MeV energy sinusoidal grating with period 292 μm and groove depth 60 μm has the uniform angular distribution with high radiation intensity. (paper)

  10. Diffraction gratings metrology and ray-tracing results for an XUV Raman spectrometer at FLASH.

    Science.gov (United States)

    Dziarzhytski, Siarhei; Siewert, Frank; Sokolov, Andrey; Gwalt, Grzegorz; Seliger, Tino; Rübhausen, Michael; Weigelt, Holger; Brenner, Günter

    2018-01-01

    The extreme-ultraviolet double-stage imaging Raman spectrometer is a permanent experimental endstation at the plane-grating monochromator beamline branch PG1 at FLASH at DESY in Hamburg, Germany. This unique instrument covers the photon energy range from 20 to 200 eV with high energy resolution of about 2 to 20 meV (design values) featuring an efficient elastic line suppression as well as effective stray light rejection. Such a design enables studies of low-energy excitations like, for example, phonons in solids close to the vicinity of the elastic line. The Raman spectrometer effectively operates with four reflective off-axial parabolic mirrors and two plane-grating units. The optics quality and their precise alignment are crucial to guarantee best performance of the instrument. Here, results on a comprehensive investigation of the quality of the spectrometer diffraction gratings are presented. The gratings have been characterized by ex situ metrology at the BESSY-II Optics Laboratory, employing slope measuring deflectometry and interferometry as well as atomic force microscopy studies. The efficiency of these key optical elements has been measured at the at-wavelength metrology laboratory using the reflectometer at the BESSY-II Optics beamline. Also, the metrology results are discussed with respect to the expected resolving power of the instrument by including them in ray-tracing studies of the instrument.

  11. Diffraction by a grating made of a uniaxial dielectric-magnetic medium exhibiting negative refraction

    Energy Technology Data Exchange (ETDEWEB)

    Depine, Ricardo A [Grupo de Electromagnetismo Aplicado, Departamento de FIsica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon I, 1428 Buenos Aires (Argentina); Lakhtakia, Akhlesh [CATMAS-Computational and Theoretical Materials Sciences Group, Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802-6812 (United States); Department of Physics, Imperial College, London SW7 2BZ (United Kingdom)

    2005-08-01

    Diffraction of linearly polarized plane electromagnetic waves at the periodically corrugated boundary of vacuum and a linear, homogeneous, uniaxial, dielectric-magnetic medium is formulated as a boundary-value problem and solved using the Rayleigh method. The focus is on situations where the diffracted fields maintain the same polarization state as the s- or p-polarized incident plane wave. Attention is paid to two classes of diffracting media: those with negative definite permittivity and permeability tensors, and those with indefinite permittivity and permeability tensors. For the situations investigated, whereas the dispersion equations in the diffracting medium turn out to be elliptic for the first class of diffracting media, they are hyperbolic for the second class. Examples are reported with the first class of diffracting media of instances when the grating acts either as a positively refracting interface or as a negatively refracting interface. For the second class of diffracting media, hyperbolic dispersion equations imply the possibility of an infinite number of refraction channels.

  12. Design of aberration compensation element for the measurement of diffraction efficiency of the beam sampling grating

    Science.gov (United States)

    Sun, Hao

    2012-10-01

    A diffraction optical element (DOE) is designed to compensate the aberration induced by beam sampling grating (BSG), for analyzing the uniformity of diffraction efficiency of BSG quickly and accurately. So it is suitable for a matrix CCD to receive the aberration-free diffraction beam in the defocusing position directly. The DOE with the same size of the BSG is placed closly to the BSG, and the fringes of the DOE can be obtained by computer generated hologram based on holographic interference. Using genetic algorithm, the spatial frequency of the hologram is determined to meet the process constraint of laser directly writing by changing parameters of the measurement path. The fringe distribution of the hologram for laser direct writing can be calculated according to the iterative algorithm.

  13. Color dynamics of diffraction gratings: evaluation and applications in optical security

    Science.gov (United States)

    Pires, Paulo; Rebordo, Jose Manuel

    1999-12-01

    We looked for design methodologies that cope with optical specifications described in terms of trajectories in the CIE (Commission Internationale de l Eclairage) 1976 chromaticity diagram in the context of low-cost mass-reproduction processes that inevitably introduce changes in the design of a diffractive device for security applications. The mathematics of the design process can be strongly simplified if the theory of planar waveguides (in integrated optics) is used to estimate, with sufficient accuracy, the position of Wood singularities, responsible for the more-interesting visual features of a grating. We show how to use such a model to assess color dynamics variations that are due to production and to estimate domains within the space of grating parameters that enable both first- and second-level security features to be implemented simultaneously. All the results are compared with the values obtained by rigorous coupled-wave analysis.

  14. Binary Pseudo-Random Gratings and Arrays for Calibration of Modulation Transfer Functions of Surface Profilometers

    Energy Technology Data Exchange (ETDEWEB)

    Barber, Samuel K.; Anderson, Erik D.; Cambie, Rossana; McKinney, Wayne R.; Takacs, Peter Z.; Stover, John C.; Voronov, Dmitriy L.; Yashchuk, Valeriy V.

    2009-09-11

    A technique for precise measurement of the modulation transfer function (MTF), suitable for characterization of a broad class of surface profilometers, is investigated in detail. The technique suggested in [Proc. SPIE 7077-7, (2007), Opt. Eng. 47(7), 073602-1-5 (2008)]is based on use of binary pseudo-random (BPR) gratings and arrays as standard MTF test surfaces. Unlike most conventional test surfaces, BPR gratings and arrays possess white-noise-like inherent power spectral densities (PSD), allowing the direct determination of the one- and two-dimensional MTF, respectively, with a sensitivity uniform over the entire spatial frequency range of a profiler. In the cited work, a one dimensional realization of the suggested method based on use of BPR gratings has been demonstrated. Here, a high-confidence of the MTF calibration technique is demonstrated via cross comparison measurements of a number of two dimensional BPR arrays using two different interferometric microscopes and a scatterometer. We also present the results of application of the experimentally determined MTF correction to the measurement taken with the MicromapTM-570 interferometric microscope of the surface roughness of a super-polished test mirror. In this particular case, without accounting for the instrumental MTF, the surface rms roughness over half of the instrumental spatial frequency bandwidth would be underestimated by a factor of approximately 1.4.

  15. Characterization of diffraction gratings scattering in uv and ir for space applications

    Science.gov (United States)

    Achour, Sakina; Kuperman-Le Bihan, Quentin; Etcheto, Pierre

    2017-09-01

    The use of Bidirectional Scatter Distribution Function (BSDF) in space industry and especially when designing telescopes is a key feature. Indeed when speaking about space industry, one can immediately think about stray light issues. Those important phenomena are directly linked to light scattering. Standard BSDF measurement goniophotometers often have a resolution of about 0.1° and are mainly working in or close to the visible spectrum. This resolution is far too loose to characterize ultra-polished surfaces. Besides, wavelength range of BSDF measurements for space projects needs to be done far from visible range. How can we measure BSDF of ultra-polished surfaces and diffraction gratings in the UV and IR range with high resolution? We worked on developing a new goniophometer bench in order to be able to characterize scattering of ultra-polished surfaces and diffraction gratings used in everyday space applications. This ten meters long bench was developed using a collimated beam approach as opposed to goniophotometer using focused beam. Sources used for IR characterization were CO2 (10.6?m) and Helium Neon (3.39?m) lasers. Regarding UV sources, a collimated and spatially filtered UV LED was used. The detection was ensure by a photomultiplier coupled with synchronous detection as well as a MCT InSb detector. The so-built BSDF measurement instrument allowed us to measure BSDF of ultra-polished surfaces as well as diffraction gratings with an angular resolution of 0.02° and a dynamic of 1013 in the visible range. In IR as well as in UV we manage to get 109 with same angular resolution of 0.02°. The 1m arm and translation stages allows us to measure samples up to 200mm. Thanks to such a device allowing ultra-polished materials as well as diffraction gratings scattering characterization, it is possible to implement those BSDF measurements into simulation software and predict stray light issues. This is a big help for space industry engineers to apprehend stray light

  16. Photon control by multi-periodic binary grating waveguides: A coupled-mode theory approach

    DEFF Research Database (Denmark)

    Adam, Jost; Lüder, Hannes; Gerken, Martina

    - taneous control over multiple spectral resonance positions and relative intensities. The experimental findings were theoretically backed up by a rigorous coupled-wave analysis (RCWA) approach, yielding the leaky modes’ complex propagation constants and diffraction efficiencies. This approach, however, can...... only lead to quantitative results outside the device’s band gaps, since only radiative propagation loss is calculated.n order to provide more physical and quantitative insight to grating-induced waveguide losses, we implemented a coupled-mode theory (CMT) approach for the semi-analytical treatment...

  17. Enhancing the performance of multilayer-dielectric diffraction gratings through cleaning process modifications and defect mitigation

    Science.gov (United States)

    Liddell, Heather P. H.

    2014-05-01

    The laser-damage resistance of multilayer-dielectric (MLD) pulse compressor gratings currently limits the energy performance of the petawatt-class OMEGA EP laser system at University of Rochester's Laboratory for Laser Energetics. The cleanliness of these components is of paramount importance; contaminants can act as absorbers during laser irradiation, initiating intense local heating and catastrophic laser-induced damage. Unfortunately, some of the most effective cleaning methods for MLD gratings - usually involving high temperatures and strong acids or bases - can themselves induce chemical degradation and thermal stresses, leading to coating delamination and defects. This work explores ways to improve the laser-damage resistance of MLD gratings through modifications to the final cleaning phase of the manufacturing process. Processes of defect formation are investigated through a combination of chemical cleaning experiments, microscopy, and modeling. We use a fracture-mechanics approach to formulate a mechanism for the initiation of micrometer-scale delamination defects that are commonly observed after chemical cleaning. The stress responses of MLD coatings to elevated-temperature chemical cleaning are estimated using a thermomechanical model, enabling us to study the effects of substrate thickness, solution temperature, and heating rates on coating stresses (and thus the risk of stress-induced failure). Finally, a low-temperature chemical cleaning approach is developed to improve laser-damage resistance while avoiding defect formation and mitigating coating stresses. We find that grating coupons cleaned using the optimized method consistently meet OMEGA EP requirements on diffraction efficiency and 1054-nm laser-damage resistance at 10 ps.

  18. Influence of analyzed signals fiber-optic transmission system on spread function of the diffraction grating spectral device

    Science.gov (United States)

    Kazakov, Vasily I.; Moskaletz, Oleg D.; Paraskun, Arthur S.; Zhdanov, Arseny Yu.

    2017-08-01

    Fiber-optic transmission system of analyzed signal is considered to allow signals transmission from optical sources with either impossible or undesirable contact. Diffraction grating spectral device is chosen as investigation system. It should be noted that diffraction grating operates with transmitted light but not reflected. Influence of optical fiber consists in the distortion of wave front incident on the spectral device. Front distortion leads to a broadening of the device spread function in all diffraction orders, and as a consequence, to a deterioration in the device resolution. In this case, the complex spread function is a reaction of the device to the homogeneous plane monochromatic wave which clearly links the input-output of spectral device. Fiber-optic system influence is determined by introducing a fictitious transparency located directly in front of the diffraction grating. Research of the effect the fiber-optic system has on the spread function of the diffraction grating spectral device is made in two ways. On one hand, mathematical model is proposed to describe the influence of a single-mode optical fiber to a spread function of the diffraction grating spectral device. We performed computer simulations of the analyzed signal transmission from the end of the optical fiber to the photodetector based on the proposed model. The calculations are performed for a single-mode optical fiber with a core diameter of 8 microns. On the other hand, experimental laboratory set up of the diffraction grating spectral device with a fiber optic transmission system is created. Theoretical calculations are compared with the experimental results.

  19. Diffraction efficiency of 200-nm-period critical-angle transmission gratings in the soft x-ray and extreme ultraviolet wavelength bands

    International Nuclear Information System (INIS)

    Heilmann, Ralf K.; Ahn, Minseung; Bruccoleri, Alex; Chang, Chih-Hao; Gullikson, Eric M.; Mukherjee, Pran; Schattenburg, Mark L.

    2011-01-01

    We report on measurements of the diffraction efficiency of 200-nm-period freestanding blazed transmission gratings for wavelengths in the 0.96 to 19.4 nm range. These critical-angle transmission (CAT) gratings achieve highly efficient blazing over a broad band via total external reflection off the sidewalls of smooth, tens of nanometer thin ultrahigh aspect-ratio silicon grating bars and thus combine the advantages of blazed x-ray reflection gratings with those of more conventional x-ray transmission gratings. Prototype gratings with maximum depths of 3.2 and 6 μm were investigated at two different blaze angles. In these initial CAT gratings the grating bars are monolithically connected to a cross support mesh that only leaves less than half of the grating area unobstructed. Because of our initial fabrication approach, the support mesh bars feature a strongly trapezoidal cross section that leads to varying CAT grating depths and partial absorption of diffracted orders. While theory predicts broadband absolute diffraction efficiencies as high as 60% for ideal CAT gratings without a support mesh, experimental results show efficiencies in the range of ∼50-100% of theoretical predictions when taking the effects of the support mesh into account. Future minimization of the support mesh therefore promises broadband CAT grating absolute diffraction efficiencies of 50% or higher.

  20. Nonlinear focusing of ultrasonic waves by an axisymmetric diffraction grating embedded in water

    Energy Technology Data Exchange (ETDEWEB)

    Jiménez, N.; Picó, R. [Instituto de Investigación para la Gestión Integrada de zonas Costeras, Universitat Politècnica de València, Paranimf 1, 46730 Grao de Gandia, València (Spain); Romero-García, V. [LUNAM Université, Université du Maine, LAUM UMR CNRS 6613, Av. O. Messiaen, 72085 Le Mans (France); Garcia-Raffi, L. M. [Instituto Universitario de Matemática Pura y Aplicada, Universitat Politècnica de València, Camino de Vera s/n, 46022 València (Spain); Staliunas, K. [ICREA, Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, Colom, 11, E-08222 Terrassa, Barcelona (Spain)

    2015-11-16

    We report the nonlinear focusing of ultrasonic waves by an axisymmetric diffraction grating immersed in water. In the linear regime, the system presents high focal gain (32 dB), with a narrow beam-width and intense side lobes as it is common in focusing by Fresnel-like lenses. Activating the nonlinearity of the host medium by using high amplitude incident waves, the focusing properties of the lens dramatically change. Theoretical predictions show that the focal gain of the system extraordinary increases in the strongly nonlinear regime (Mach number of 6.1 × 10{sup −4}). Particularly, the harmonic generation is locally activated at the focal spot, and the second harmonic beam is characterized by strongly reduced side-lobes and an excellent beam profile as experiments show in agreement with theory. The results can motivate applications in medical therapy or second harmonic imaging.

  1. High-power fiber laser with a polarizing diffraction grating milled on the facet of an optical fiber

    Czech Academy of Sciences Publication Activity Database

    Vaněk, Martin; Vaniš, Jan; Baravets, Yauhen; Todorov, Filip; Čtyroký, Jiří; Honzátko, Pavel

    2016-01-01

    Roč. 24, č. 26 (2016), s. 30225-30233 ISSN 1094-4087 R&D Projects: GA ČR GA15-07908S Institutional support: RVO:67985882 Keywords : Optical fibers * Polarization * Diffraction gratings Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 3.307, year: 2016

  2. Enhanced diffraction efficiency of mixed volume gratings with nanorod dopants in polymeric nanocomposite

    Science.gov (United States)

    Cao, Liangcai; Wu, Shenghan; Hao, Jinping; Zhu, Chen; He, Zehao; Zhang, Zheyuan; Zong, Song; Zhang, Fushi; Jin, Guofan

    2017-10-01

    We propose a method to improve the holographic performance of a volume holographic material by the particle-shape dependence of doped nanoparticles. Previously reported methods are based on changing the doping concentration of dopants and the diameter of nanoparticles or modifying the surface of nanoparticles. When transverse surface plasmon resonance of optimized gold nanorods shifts near the recording wavelength, experiments confirmed that enhancement of diffraction efficiency by efficient dopants of gold nanorods is better than that of gold nanospheres. The enhancement effects under optimal mixing conditions occur with a crucial factor of maximum absorption intensity at the recording wavelength using the particle-shape dependence of doping nanorods. The gold nanorods with an average diameter of 10 ± 2.1 nm and an average length of 34 ± 5 nm are doped in Phenanthrenequinone-doped poly(methyl methacrylate) photopolymers. The diffraction efficiency of volume holographic grating in the photopolymer doped with nanorods is 18.5% higher than that in the photopolymer doped with nanospheres and 29.6% higher than that in the pure photopolymer.

  3. Effects of tilted angle of Bragg facets on the performance of successive strips based Bragg concave diffraction grating

    Science.gov (United States)

    Du, Bingzheng; Zhu, Jingping; Mao, Yuzheng; Wang, Kai; Chen, Huibing; Hou, Xun

    2018-03-01

    The effects of the tilted angle of facets on the diffraction orders, diffraction spectra, dispersion power, and the neighbor channel crosstalk of successive etching strips based Bragg concave diffraction grating (Bragg-CDG) are studied in this paper. The electric field distribution and diffraction spectra of four Bragg-CDGs with different tilted angles are calculated by numerical simulations. With the reflection condition of Bragg facets constant, the blazing order cannot change with the titled angle. As the tilted angle increases, the number of diffraction orders of Bragg-CDG will decrease, thereby concentrating more energy on the blazing order and improving the uniformity of diffraction spectra. In addition, the dispersion power of Bragg-CDG can be improved and the neighbor channel crosstalk of devices can be reduced by increasing the tilted angle. This work is beneficial to optimize the performance of Bragg-CDG.

  4. Water-cooled ion-milled diffraction gratings for the synchrotron radiation community

    Energy Technology Data Exchange (ETDEWEB)

    McKinney, W.R.; Shannon, C.L.; Shults, E.N.

    1993-08-01

    Key technical and strategic choices are reviewed, leading to the fabrication method of ion-milled grating grooves for the monochromators at the Advanced Light Source (ALS) at Lawrence Berkeley Laboratory (LBL), and for other synchrotrons. Several laboratories and their industrial partners have joined to manufacture gratings with essentially theoretical performance. Metrology -data and theoretical comparisons are given for square wave profile grating samples ion-milled into electroless nickel surfaces. The extensive capabilities of Hughes Aircraft in grating manufacture are reviewed.

  5. Accurate characterization of 3D diffraction gratings using time domain discontinuous Galerkin method with exact absorbing boundary conditions

    KAUST Repository

    Sirenko, Kostyantyn

    2013-07-01

    Exact absorbing and periodic boundary conditions allow to truncate grating problems\\' infinite physical domains without introducing any errors. This work presents exact absorbing boundary conditions for 3D diffraction gratings and describes their discretization within a high-order time-domain discontinuous Galerkin finite element method (TD-DG-FEM). The error introduced by the boundary condition discretization matches that of the TD-DG-FEM; this results in an optimal solver in terms of accuracy and computation time. Numerical results demonstrate the superiority of this solver over TD-DG-FEM with perfectly matched layers (PML)-based domain truncation. © 2013 IEEE.

  6. Diffraction from polarization holographic gratings with surface relief in side-chain azobenzene polyesters

    DEFF Research Database (Denmark)

    Naydenova, I; Nikolova, L; Todorov, T

    1998-01-01

    We investigate the polarization properties of holographic gratings in side-chain azobenzene polyesters in which an anisotropic grating that is due to photoinduced linear and circular birefringence is recorded in the volume of the material and a relief grating appears on the surface. A theoretical...... in the appearance of a surface relief with doubled frequency....

  7. Study of the local structure of binary surfaces by electron diffraction (XPS, LEED)

    OpenAIRE

    Gereová, Katarína

    2006-01-01

    Study of local structure of binary surface with usage of ultra-thin film of cerium deposited on a Pd (111) single-crystal surface is presented. X-ray photoelectron spectroscopy and diffraction (XPS, XPD), angle resolved UV photoemission spectroscopy (ARUPS) and low energy electron diffraction (LEED) was used for our investigations. LEED and X-ray excited photoemission intensities results represent a surface-geometrical structure. As well, mapping of ultra-violet photoelectron intensities as a...

  8. Diffraction of electromagnetic waves by a metallic bar grating with a defect in dielectric filling of the slits

    Science.gov (United States)

    Kochetova, Lyudmila A.; Prosvirnin, Sergey L.

    2018-04-01

    The problem of electromagnetic wave diffraction by the metallic bar grating with inhomogeneous dielectric filling of each slit between bars has been investigated by using the mode matching technique. The transmission and the inner field distribution have been analyzed for the structure which has a single defect in the periodic filling of slits. Such periodic structures are of particular interest for applications in optics, as they have the ability to concentrate a strong inner electromagnetic field and are characterized by high-Q transmission resonances. We use a simple approach to control the width and location of the stopband of the structure by placing a defect in the periodic filling of the grating slits. As a result, we observe the narrow resonance of transmission in terms of stopband width of the defect-free grating and confinement of strong inner electromagnetic field. By changing the permittivity of the defect layer we can shift the frequency of the resonant transmission.

  9. Measurement method for roll angular displacement with a high resolution by using diffraction gratings and a heterodyne interferometer

    International Nuclear Information System (INIS)

    Tang, Shanzhi; Wang, Zhao; Gao, Jianmin; Guo, Junjie

    2014-01-01

    The roll angle measurement is difficult to be achieved directly using a typical commercial interferometer due to its low sensitivity in axial direction, where the axial direction is orthogonal to the plane of the roll angular displacement. A roll angle measurement method combined diffraction gratings with a laser heterodyne interferometer is discussed in this paper. The diffraction grating placed in the plane of a roll angular displacement and the interferometer arranged in the plane's orthogonal direction, constitute the measurement pattern for the roll angle with high resolution. The roll angular displacement, considered as the linear, can be tested precisely when the corresponding angle is very small. Using the proposed method, the angle roll measurement obtains the high resolution of 0.002 ″ . Experiment has proved its feasibility and practicability

  10. Integral staggered point-matching method for millimeter-wave reflective diffraction gratings on electron cyclotron heating systems

    International Nuclear Information System (INIS)

    Xia, Donghui; Huang, Mei; Wang, Zhijiang; Zhang, Feng; Zhuang, Ge

    2016-01-01

    Highlights: • The integral staggered point-matching method for design of polarizers on the ECH systems is presented. • The availability of the integral staggered point-matching method is checked by numerical calculations. • Two polarizers are designed with the integral staggered point-matching method and the experimental results are given. - Abstract: The reflective diffraction gratings are widely used in the high power electron cyclotron heating systems for polarization strategy. This paper presents a method which we call “the integral staggered point-matching method” for design of reflective diffraction gratings. This method is based on the integral point-matching method. However, it effectively removes the convergence problems and tedious calculations of the integral point-matching method, making it easier to be used for a beginner. A code is developed based on this method. The calculation results of the integral staggered point-matching method are compared with the integral point-matching method, the coordinate transformation method and the low power measurement results. It indicates that the integral staggered point-matching method can be used as an optional method for the design of reflective diffraction gratings in electron cyclotron heating systems.

  11. Integral staggered point-matching method for millimeter-wave reflective diffraction gratings on electron cyclotron heating systems

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Donghui [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, 430074 Wuhan (China); Huang, Mei [Southwestern Institute of Physics, 610041 Chengdu (China); Wang, Zhijiang, E-mail: wangzj@hust.edu.cn [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, 430074 Wuhan (China); Zhang, Feng [Southwestern Institute of Physics, 610041 Chengdu (China); Zhuang, Ge [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, 430074 Wuhan (China)

    2016-10-15

    Highlights: • The integral staggered point-matching method for design of polarizers on the ECH systems is presented. • The availability of the integral staggered point-matching method is checked by numerical calculations. • Two polarizers are designed with the integral staggered point-matching method and the experimental results are given. - Abstract: The reflective diffraction gratings are widely used in the high power electron cyclotron heating systems for polarization strategy. This paper presents a method which we call “the integral staggered point-matching method” for design of reflective diffraction gratings. This method is based on the integral point-matching method. However, it effectively removes the convergence problems and tedious calculations of the integral point-matching method, making it easier to be used for a beginner. A code is developed based on this method. The calculation results of the integral staggered point-matching method are compared with the integral point-matching method, the coordinate transformation method and the low power measurement results. It indicates that the integral staggered point-matching method can be used as an optional method for the design of reflective diffraction gratings in electron cyclotron heating systems.

  12. High-Density Diffraction Imaging and Non-Imaging Grating Elements for EUV and X-ray Spectroscopy Fabricated by DUV Reduction Photolithography, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — There is a need for lightweight high-density (4000+ lines/mm) novel diffraction grating elements in modern telescopes to advance EUV and X-ray astrophysics. Current...

  13. Tailoring Spectral Properties of Binary PT-Symmetric Gratings by Duty-Cycle Methods

    DEFF Research Database (Denmark)

    Lupu, Anatole T.; Benisty, Henri; Lavrinenko, Andrei

    2016-01-01

    We explore the frequency selective functionalities of a nonuniform PT-symmetric Bragg grating with modulated complex index profile. We start by assessing the possibility to achieve an efficient apodization of the PT-symmetric Bragg grating spectral response by using direct adaptations of the conv......We explore the frequency selective functionalities of a nonuniform PT-symmetric Bragg grating with modulated complex index profile. We start by assessing the possibility to achieve an efficient apodization of the PT-symmetric Bragg grating spectral response by using direct adaptations...

  14. Accuracy analysis of simplified and rigorous numerical methods applied to binary nanopatterning gratings in non-paraxial domain

    Energy Technology Data Exchange (ETDEWEB)

    Francés, Jorge; Bleda, Sergio; Gallego, Sergi; Neipp, Cristian; Márquez, Andrés [Instituto Universitario de Física Aplicada a las Ciencias y las Tecnologías, Universidad de Alicante, Crtra. San Vicente del Raspeig S/N, Alicante E-03080 (Spain); Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal, Universidad de Alicante, Crtra. San Vicente del Raspeig S/N, Alicante E-03080 (Spain); Pascual, Inmaculada [Instituto Universitario de Física Aplicada a las Ciencias y las Tecnologías, Universidad de Alicante, Crtra. San Vicente del Raspeig S/N, Alicante E-03080 (Spain); Departamento de Óptica, Farmacología y Anatomía, Universidad de Alicante, Crtra. San Vicente del Raspeig S/N, Alicante E-03080 (Spain); Beléndez, Augusto, E-mail: a.belendez@ua.es [Instituto Universitario de Física Aplicada a las Ciencias y las Tecnologías, Universidad de Alicante, Crtra. San Vicente del Raspeig S/N, Alicante E-03080 (Spain); Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal, Universidad de Alicante, Crtra. San Vicente del Raspeig S/N, Alicante E-03080 (Spain)

    2013-11-01

    A set of simplified and rigorous electromagnetic vector theories is used for analyzing the transmittance characteristics of diffraction phase gratings. The scalar diffraction theory and the effective medium theory are validated with the exact results obtained via the rigorous coupled-wave theory and the finite-difference time-domain method. The effects of surface profile parameters and also the angle of incidence is demonstrated to be a limiting factor in the accuracy of these theories. Therefore, the error of both simplified theories is also analyzed in non-paraxial domain with the intention of establishing a specific range of validity for both simplified theories.

  15. Optimal wavelength scale diffraction gratings for light trapping in solar cells

    International Nuclear Information System (INIS)

    Chong, Teck Kong; Wilson, Jonathan; Mokkapati, Sudha; Catchpole, Kylie R

    2012-01-01

    Dielectric gratings are a promising method of achieving light trapping for thin crystalline silicon solar cells. In this paper, we systematically examine the potential performance of thin silicon solar cells with either silicon (Si) or titanium dioxide (TiO 2 ) gratings using numerical simulations. The square pyramid structure with silicon nitride coating provides the best light trapping among all the symmetric structures investigated, with 89% of the expected short circuit current density of the Lambertian case. For structures where the grating is at the rear of the cell, we show that the light trapping provided by the square pyramid and the checkerboard structure is almost identical. Introducing asymmetry into the grating structures can further improve their light trapping properties. An optimized Si skewed pyramid grating on the front surface of the solar cell results in a maximum short circuit current density, J sc , of 33.4 mA cm −2 , which is 91% of the J sc expected from an ideal Lambertian scatterer. An optimized Si skewed pyramid grating on the rear performs as well as a rear Lambertian scatterer and an optimized TiO 2 grating on the rear results in 84% of the J sc expected from an optimized Si grating. The results show that submicron symmetric and skewed pyramids of Si or TiO 2 are a highly effective way of achieving light trapping in thin film solar cells. TiO 2 structures would have the additional advantage of not increasing recombination within the cell. (paper)

  16. Optical dipole mirror for cold atoms based on a metallic diffraction grating

    DEFF Research Database (Denmark)

    Kawalec, Tomasz; Bartoszek-Bober, Dobroslawa; Panas, Roman

    2014-01-01

    We report on the realization of a plasmonic dipole mirror for cold atoms based on a metallic grating coupler. A cloud of atoms is reflected by the repulsive potential generated by surface plasmon polaritons (SPPs) excited on a reflection gold grating by a 780 nm laser beam. Experimentally...

  17. Optical dipole mirror for cold atoms based on a metallic diffraction grating

    DEFF Research Database (Denmark)

    Kawalec, Tomasz; Bartoszek-Bober, Dobroslawa; Panas, Roman

    We report on the realization of a plasmonic dipole mirror for cold atoms based on a metallic grating coupler. A cloud of atoms is reflected by the repulsive potential generated by surface plasmon polaritons (SPPs) excited on a reflection gold grating by a 780 nm laser beam. Experimentally...

  18. Optimizing the coupling of output of a quasi-optical gyrotron owing to a diffraction grating with ellipsoidal support

    International Nuclear Information System (INIS)

    Hogge, J.P.

    1993-12-01

    The output scheme of a quasi-optical gyrotron has been optimized in order to produce a gaussian output microwave beam suitable for transmission over long distances. The technique which has been applied consists of substituting one of the mirrors of the Fabry-Perot resonator in which the particle-wave interaction takes place by a diffraction grating placed in the -1 order Littrow mount and designed such that only orders -1 and 0 can propagate. In such a configuration, the diffraction angle of the order -1 coincides exactly with the incidence direction, thus providing a feedback in the cavity, whereas the order 0 constitutes the output of the resonator. A theoretical study of the power content in each diffracted order of a planar grating of infinite extent with equally spaced linear grooves as a function of the grating parameters has been performed. It has been shown that parameter domains can be found, which provide appropriate efficiencies in both orders for an application on a quasi-optical gyrotron. The Littrow condition was then adapted in order to match the spherical wavefronts of a gaussian beam incident on a possibly non-planar surface. The grooves become thus curvilinear and are no longer equally spaced. Measurements made on a cold test stand have confirmed the validity of the Littrow condition extension and allowed to determine its limits. It has also been shown that this type of cavity provides a mode having an optimal gaussian content and giving a minimal cavity transmission. The angular dispersion of the grating leads to a higher cavity transmission and to a slightly lower gaussian content for the adjacent resonator modes. The fundamental eigenmode electric field profile has been measured inside the cavity and is similar to that of an equivalent resonator made with two spherical mirrors. (author) figs., tabs., 141 refs

  19. Enhancement of diffraction efficiency of laminar-type diffraction gratings overcoated with diamond-like carbon (DLC) in soft x-ray region

    Energy Technology Data Exchange (ETDEWEB)

    Koike, Masato, E-mail: koike.masato@jaea.go.jp; Imazono, Takashi [Quantum Beam Science Center, Japan Atomic Energy Agency, 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215 Japan (Japan); Nagano, Tetsuya; Sasai, Hiroyuki; Oue, Yuki; Yonezawa, Zeno; Kuramoto, Satoshi [Device Dept., Shimadzu Corp., 1Nishinokyo-Kuwabara-cho, Nakagyo-ku, Kyoto 604-8511 Japan (Japan); Terauchi, Masami [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 Japan (Japan); Takahashi, Hideyuki [Science Equipment Sales Dept., JEOL Ltd., 2-1-1 Ohtemachi, Chiyoda-ku, Tokyo 100-0004 Japan (Japan); Notoya, Satoshi; Murano, Takanori [SA Business Unit, JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558 Japan (Japan)

    2016-07-27

    Boron is the critical trace element in the production of high quality steel, creating a great demand for an efficient detection method of the B-K emission band at around 6.76 nm. To meet this demand we made a simulation study and obtained a practical method to improve the diffraction efficiency of metal-coated laminar-type gratings for a grazing incidence flat-field spectrograph by overcoating a sufficiently transparent high-density material. In the simulation the diffraction efficiency in a spectral region of 3.5-8.5 nm was computed for several combinations of overcoating materials and coating metals, with various thicknesses of the overcoating layer. The result obtained are: (1) the best overcoating material is high-density diamond-like carbon (DLC) having a density of 3.1 g/cm{sup 3}, (2) its optimum thickness is 24 nm at an angle of incidence of 87.0°, and (3) with this thickness the first-order diffraction efficiency is expected to reach 29.7 %, which well exceeds 15.6 % for Ni-coated (or 14.1 % for Au-coated) grating.

  20. Efficiency and stray light measurements and calculations of diffraction gratings for the ALS

    International Nuclear Information System (INIS)

    McKinney, W.R.; Mossessian, D.; Gullikson, E.; Heimann, P.

    1994-07-01

    Water cooled gratings manufactured for spherical grating monochromators of the Advanced Light Source beamlines 7.0, 8.0 and 9.0 were measured with the laser plasma source and reflectometer in the Center for X-ray Optics at LBL. The square-wave gratings are ion-milled into the polished electroless nickel surface after patterning by holographic photolithography. Absolute efficiency data are compared with exact electromagnetic theory calculation. Inter-order stray light and groove depths can be estimated from the measurements

  1. Diffraction grating strain gauge method: error analysis and its application for the residual stress measurement in thermal barrier coatings

    Science.gov (United States)

    Yin, Yuanjie; Fan, Bozhao; He, Wei; Dai, Xianglu; Guo, Baoqiao; Xie, Huimin

    2018-03-01

    Diffraction grating strain gauge (DGSG) is an optical strain measurement method. Based on this method, a six-spot diffraction grating strain gauge (S-DGSG) system has been developed with the advantages of high and adjustable sensitivity, compact structure, and non-contact measurement. In this study, this system is applied for the residual stress measurement in thermal barrier coatings (TBCs) combining the hole-drilling method. During the experiment, the specimen’s location is supposed to be reset accurately before and after the hole-drilling, however, it is found that the rigid body displacements from the resetting process could seriously influence the measurement accuracy. In order to understand and eliminate the effects from the rigid body displacements, such as the three-dimensional (3D) rotations and the out-of-plane displacement of the grating, the measurement error of this system is systematically analyzed, and an optimized method is proposed. Moreover, a numerical experiment and a verified tensile test are conducted, and the results verify the applicability of this optimized method successfully. Finally, combining this optimized method, a residual stress measurement experiment is conducted, and the results show that this method can be applied to measure the residual stress in TBCs.

  2. Attenuation measurements with ultrasonic diffraction grating show dependence upon particle size of slurry and viscosity of base liquid.

    Science.gov (United States)

    Greenwood, Margaret Stautberg

    2018-03-01

    How can using an ultrasonic diffraction grating lead to slurry characterization? The diffraction grating, which is formed by machining triangular grooves on the flat surface of an aluminum unit, has send and receive transducers fastened to the unit at an angle of 30°. The ultrasonic beam strikes the back of the grating, in contact with the slurry, and reflects a beam to the receive transducer; m = 0 and m = 1 beams are transmitted into the slurry. The angle of the m = 1 beam changes with frequency and, at the critical frequency f CR , it reaches 90°. When f < f CR , the m = 1 beam disappears, its energy is shared with all other beams, producing a peak in the receive transducer. The change in peak height with slurry concentration determines the attenuation; the frequency at the peak yields the velocity of sound. The attenuation has been measured for polystyrene spheres, ranging in size from 98 µm to 463 µm, and slurry concentrations up to 20 wt%. When the spheres are immersed in water, sugar water, or mineral oil, the attenuation measurements show the effect of particle diameter and the viscosity of the base fluid. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. New Class of Multi-Channel Spectrometers Based on Diffraction Grating Array, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Remote chemical analysis via spectroscopy is an important tool in the arsenal or Earth and Planetary Science. Grating technology, which is the centerpiece of most...

  4. Low cost and high performance GPON, GEPON and RFoG optical network pentaplexer module design using diffractive grating approach

    Science.gov (United States)

    Chen, I.-Ju; Chi, Chang-Chia; Tarn, Chen-Wen

    2016-01-01

    A new architecture of a pentaplexer transceiver module which can be used in GPON/GEPON and RFoG triple play optical networks with supporting of the multiple optical wavelengths of 1310 nm, 1490 nm, 1550 nm, 1610 nm, and 1650 nm, is proposed. By using diffractive grating elements combing with market readily available GRIN (Gradient-Index) lens, grating, mirrors, beamsplitter, LDs (Laser Diodes), and PDs (Photodetectors), the proposed design have the advantages of low cost, high efficiency/performance, easy design and manufacturing, over the contemporary triplex transceivers which are made of multilayer filters or waveguides that increase the complexity of manufacturing and reduce the performance efficiency. With the proposed design, a pentaplexer system can accommodate GPON/GEPON, RFoG, and monitoring integration services, total five optical wavelength channels into a hybrid-integrated TO-CAN package platform with sufficient efficiency.

  5. Diffraction behavior of a birefringence grating and a surface relief grating recorded on an azo polymer film by using writing beams with a (+45 .deg. , -45 .deg. ) polarization combination

    International Nuclear Information System (INIS)

    Hwang, Ui-Jung; Kim, Jung-Sung; Oh, Cha-Hwan; Lee, Geon-Joon; Lee, Young-Pak; Song, Seok-Ho; Kim, Pill-Soo; Han, Yang-Kyoo

    2004-01-01

    By employing an orthogonal linear-polarization combination, (+45 .deg. ,-45 .deg. ), we prepared a surface relief grating (SRG) and a birefringence grating (BG) on an azo polymer film. Atomic force microscopy (AFM) showed that the SRG height gradually increased, and the height was 56.5 nm at an input fluence of 63 J/cm 2 . All the diffraction orders from the gratings were measured simultaneously, and the BG characteristics were analyzed from the s and the p components of the first-order diffraction beam and the measured SRG height. The BG showed an abrupt increase in the beginning of writing, but decreased shortly later, and became smaller than the SRG at a few minutes after writing. The phase shift between the two gratings was determined to be π, which is crucial for determining the SRG formation mechanism.

  6. Experimental evaluation of enhancement of diffraction efficiency by overcoating diamond-like carbon (DLC) on soft x-ray laminar-type gratings

    Energy Technology Data Exchange (ETDEWEB)

    Imazono, Takashi, E-mail: imazono.takashi@jaea.go.jp; Koike, Masato [Quantum Beam Science Center, Japan Atomic Energy Agency, 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215 (Japan); Nagano, Tetsuya; Sasai, Hiroyuki; Oue, Yuki; Kuramoto, Satoshi [Device Department, Shimadzu Corp., 1 Nishinokyo-Kuwabara-cho, Nakagyo-ku, Kyoto 604-8511 (Japan); Terauchi, Masami [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Takahashi, Hideyuki [Science Equipment Sales Dept., JEOL Ltd., 2-1-1 Ohtemachi, Chiyoda-ku, Tokyo 100-0004 (Japan); Notoya, Satoshi; Murano, Takanori [SA Business Unit, JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558 (Japan); Gullikson, Eric M. [Center for X-ray Optics, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Bldg. 2R0400, Berkeley, CA 94720-8199 (United States)

    2016-07-27

    Efficiently detecting the B-K emission band around 6.76 nm from a trace concentration of boron in steel compounds has motivated a theoretical exploration of means of increasing the diffraction efficiency of a laminar grating with carbon overcoating. To experimentally evaluate this enhancement, a Ni grating was coated with a high-density carbon film, i.e., diamond-like carbon (DLC). The first order diffraction efficiencies of the Ni gratings coated with and without DLC were measured to be 25.8 % and 16.9 %, respectively, at a wavelength of 6.76 nm and an angle of incidence of 87.07°. The ratio of diffraction efficiency obtained experimentally vs. that calculated by numerical simulation is 0.87 for the DLC-coated Ni grating. The diffraction efficiency of a Ni grating coated with a low-density carbon film, amorphous carbon (a-C), was also slightly improved to be 19.6 %. Furthermore, a distinct minimum of the zeroth order lights of the two carbon-coated Ni gratings were observed at around 6.76 nm, which is coincident with the maximum of the first order light.

  7. Neutron diffraction on a moving grating and quasi-energy of cold neutrons

    International Nuclear Information System (INIS)

    Frank, A.I.; Nosov, V.G.

    1994-01-01

    A solution is found to the problem of the motion of an absorbing or phase grating across a monochromatic neutron beam. It is found that a very close connection exists between this problem and the problem of fast periodic chopping of a neutron beam. (orig.)

  8. Molecular hydrogen occupancy in binary THF-H2 clathrate hydrates by high resolution neutron diffraction.

    Science.gov (United States)

    Hester, Keith C; Strobel, Timothy A; Sloan, E Dendy; Koh, Carolyn A; Huq, Ashfia; Schultz, Arthur J

    2006-07-27

    We have determined the time-space average filling of hydrogen molecules in a binary tetrahydrofuran (THF)-d(8) + D(2) sII clathrate hydrate using high resolution neutron diffraction. The filling of hydrogen in the lattice of a THF-d(8) clathrate hydrate occurred upon pressurization. The hydrogen molecules were localized in the small dodecahedral cavities at 20 K, with nuclear density from the hydrogen approximately spherically distributed and centered in the small cavity. With a formation pressure of 70 MPa, molecular hydrogen was found to only singly occupy the sII small cavity. This result helps explain discrepancies about the hydrogen occupancy in the THF binary hydrate system.

  9. Binary sub-wavelength diffractive lenses with long focal depth and high transverse resolution.

    Science.gov (United States)

    Feng, Di; Ou, Pan; Feng, Li-Shuang; Hu, Shu-Ling; Zhang, Chun-Xi

    2008-12-08

    This study explores two-dimensional binary sub-wavelength diffractive lenses (BSDLs) for implementing long focal depth and high transverse resolution based on the rigorous electromagnetic theory and the finite-difference time-domain method. Focusing performances, such as the actual focal depth, the ratio between the focal depth of the designed BSDL and the focal depth of the conventional sub-wavelength lens and the spot size of the central lobe at the actual focal plane, for different f-numbers, have been studied in the case of TE incidence polarization wave. The rigorous numerical results indicate that the designed BSDLs indeed have long focal depth and high transverse resolution by modulating the binary sub-wavelength characteristic sizes. Because BSDLs have the ability for monolithic integration and can require only single step fabrication, the investigations may provide useful information for BSDLs' application in micro-optical systems. (c) 2008 Optical Society of America

  10. Binary Super Grating (BSG) Self-Collimated Multi-Wavelength Laser

    National Research Council Canada - National Science Library

    Fay, Martin

    2001-01-01

    ...). and the underlying binary supergrating (BSG). on which the SCMWL depends. In this context, the BSG functions as a multi-wavelength reflector which can be implemented by a simple two-level etching process...

  11. High-performance and compact binary blazed grating coupler based on an asymmetric subgrating structure and vertical coupling.

    Science.gov (United States)

    Yang, Junbo; Zhou, Zhiping; Jia, Honghui; Zhang, Xueao; Qin, ShiQiao

    2011-07-15

    A high-performance and compact fiber-to-waveguide binary blazed subwavelength grating coupler was designed based on silicon-on-insulator. By the appropriate choice of waveguide/grating parameters, including thicknesses, periods, height, and fill factor, to optimize the mode matching, a relatively high coupling efficiency was obtained for the fiber and waveguide interface. Moreover, perfectly vertical fiber coupling is achieved by using an asymmetric subgrating structure in which a period consists of two subgratings with identical etching height and different widths. Coupling efficiency as high as 69% at a wavelength of 1.52 μm and 65% at a wavelength of 1.55 μm is calculated. Simultaneously, the 1 dB wavelength bandwidth is around 80 nm. The coupling efficiency can reach up to 80% or so if Bragg reflector layers are added. Finally, the device layout is simple, feasible, one-step etched, and compatible with standard complementary metal-oxide semiconductor technology processing. © 2011 Optical Society of America

  12. Damage threshold measurement of large-aperture diffraction grating illuminated by 10 ps laser

    International Nuclear Information System (INIS)

    Hao Xin; Wang Xiao; Huang Wanqing; Zhou Kainan; Zhao Lei; Zeng Xiaoming; Zuo Yanlei; Huang Zheng

    2012-01-01

    In chirped pulse amplification laser systems, the damage threshold of the final grating in the pulse compressor seriously limits the energy output. This paper proposes a measurement, by which the exact correlation between the local fluence and local damage characteristics can be established. This method collects the near-field intensity distribution of a cm-sized beam spot and its corresponding raster damage image through on-line monitoring and image processing, and then matches the pixels on the two images to each other. Finally the gray level in the damage image is converted in terms of damage density by microscope observation. It does not strictly require the spatial uniformity of the beam. Moreover, since the intensity fluctuation is taken into account, the damage densities versus the fluence can be extracted within one shot. (authors)

  13. Diffraction of polarized light on periodic structures

    International Nuclear Information System (INIS)

    Bukanina, V; Divakov, D; Tyutyunnik, A; Hohlov, A

    2012-01-01

    Periodic structures as photonic crystals are widely used in modern laser devices, communication technologies and for creating various beam splitters and filters. Diffraction gratings are applied for creating 3D television sets, DVD and Blu-ray drives and reflective structures (Berkley mirror). It is important to simulate diffraction on such structures to design optical systems with predetermined properties based on photonic crystals and diffraction gratings. Methods of simulating diffraction on periodic structures uses theory of Floquet-Bloch and rigorous coupled-wave analysis (RCWA). Current work is dedicated to analysis of photonic band gaps and simulating diffraction on one-dimensional binary diffraction grating using RCWA. The Maxwell's equations for isotropic media and constitutive relations based on the cgs system were used as a model.

  14. Temperature sensor based on a polymer diffraction grating with silver nanoparticles

    Science.gov (United States)

    Nuzhdin, V. I.; Valeev, V. F.; Galyautdinov, M. F.; Osin, Yu. N.; Stepanov, A. L.

    2018-01-01

    The method is suggested for producing an optical temperature noncontact sensor on a polymer polymethylmethacrylate (PMMA) substrate with a diffraction optical element formed by implanting low-energy high-dose silver ions through a surface mask. Ion implantation is performed at an energy of 30 keV, a radiation dose of 5.0 × 1016 ion cm‑2 and an ion beam current density of 2 μA cm‑2 through a surface metal mask having the form of grid with square periodical holes (cells) of size 25 μm. In the course of implantation, silver nanoparticles are produced in periodical unmasked domains of irradiated PMMA. Operation of the temperature sensor on diffraction microstructures made of polymer with silver nanoparticles is demonstrated in the range from 20 °C to 95 °C by testing it with a probe radiation of a He – Ne laser.

  15. Binary pseudo-random gratings and arrays for calibration of the modulation transfer function of surface profilometers: recent developments

    Energy Technology Data Exchange (ETDEWEB)

    Barber, Samuel K.; Soldate, Paul; Anderson, Erik H.; Cambie, Rossana; Marchesini, Stefano; McKinney, Wanye R.; Takacs, Peter Z.; Voronov, Dmitry L.; Yashchuk, Valeriy V.

    2009-07-07

    The major problem of measurement of a power spectral density (PSD) distribution of the surface heights with surface profilometers arises due to the unknown Modulation Transfer Function (MTF) of the instruments. The MTF tends to distort the PSD at higher spatial frequencies. It has been suggested [Proc. SPIE 7077-7, (2007), Opt. Eng. 47 (7), 073602-1-5 (2008)] that the instrumental MTF of a surface profiler can be precisely measured using standard test surfaces based on binary pseudo-random (BPR) patterns. In the cited work, a one dimensional (1D) realization of the suggested method based on use of BPR gratings has been demonstrated. Here, we present recent achievements made in fabricating and using two-dimensional (2D) BPR arrays that allow for a direct 2D calibration of the instrumental MTF. The 2D BPRAs were used as standard test surfaces for 2D MTF calibration of the MicromapTM-570 interferometric microscope with all available objectives. The effects of fabrication imperfections on the efficiency of calibration are also discussed.

  16. Fabrication of Vertically Aligned Carbon Nanotube or Zinc Oxide Nanorod Arrays for Optical Diffraction Gratings.

    Science.gov (United States)

    Kim, Jeong; Kim, Sun Il; Cho, Seong-Ho; Hwang, Sungwoo; Lee, Young Hee; Hur, Jaehyun

    2015-11-01

    We report on new fabrication methods for a transparent, hierarchical, and patterned electrode comprised of either carbon nanotubes or zinc oxide nanorods. Vertically aligned carbon nanotubes or zinc oxide nanorod arrays were fabricated by either chemical vapor deposition or hydrothermal growth, in combination with photolithography. A transparent conductive graphene layer or zinc oxide seed layer was employed as the transparent electrode. On the patterned surface defined using photoresist, the vertically grown carbon nanotubes or zinc oxides could produce a concentrated electric field under applied DC voltage. This periodic electric field was used to align liquid crystal molecules in localized areas within the optical cell, effectively modulating the refractive index. Depending on the material and morphology of these patterned electrodes, the diffraction efficiency presented different behavior. From this study, we established the relationship between the hierarchical structure of the different electrodes and their efficiency for modulating the refractive index. We believe that this study will pave a new path for future optoelectronic applications.

  17. Growth of isotropic domains as a mechanism of dynamic diffraction grating recording in low molecular liquid-crystalline derivatives of azobenzene.

    Science.gov (United States)

    Czajkowski, Maciej; Bartkiewicz, Stanislaw; Mysliwiec, Jaroslaw

    2012-03-15

    In this paper, we propose and explain the mechanism of dynamic molecular motions and isotropic domain formation during the diffraction grating recording in low molecular liquid-crystalline azobenzene derivatives. The photochromic molecules of 4-heptyl-4'-methoxyazobenzene, showing nematic liquid-crystalline properties close to the room temperature (from T = 34 °C), are used. A one-dimensional model of the grating formation is formulated based on in vivo polarized microscope observations. Formation and growth of the isotropic domains induced by the sinusoidally modulated Gaussian light intensity distribution is proposed as the mechanism and is used for experimental data fitting. The influence of the recording light intensity, grating period, and temperature on the domain growth rate factor is checked. © 2012 American Chemical Society

  18. Use of first-order diffraction wavelengths corresponding to dual-grating periodicities in a single fibre Bragg grating for simultaneous temperature and strain measurement

    International Nuclear Information System (INIS)

    Yam, Sui P; Brodzeli, Zourab; Rollinson, Claire M; Baxter, Greg W; Collins, Stephen F; Wade, Scott A

    2009-01-01

    A fibre Bragg grating (FBG) sensor, fabricated using a phase mask with 536 nm uniform pitch, for simultaneous temperature and strain measurement is presented. Two peaks/dips occur, at 785 and 1552 nm, due to reflection/transmission at the Bragg wavelength and at twice the Bragg wavelength, and arising primarily from FBG periodicities associated with half the phase mask periodicity and the phase mask periodicity, respectively. This grating was simple to fabricate and by having greater reflectivity at 785 nm, compared with 1552 nm, it is better suited for long-distance operation compared with similar schemes where the greater fibre attenuation at 785 nm is a significant limitation

  19. Compact double-layer subwavelength binary blazed grating 1×4 splitter based on silicon-on-insulator.

    Science.gov (United States)

    Yang, Junbo; Zhou, Zhiping; Wang, Xinjun; Wu, Danhua; Yi, Huaxiang; Yang, JianKun; Zhou, Wei

    2011-03-15

    We describe a compact double-layer waveguide grating splitter that not only achieves efficient coupling between single mode fiber and a silicon-on-insulator optical waveguide but also realizes effective splitting. By appropriate choice of waveguide/grating parameters, including thicknesses, periods, height, and fill factor to optimize the mode matching, coupling efficiency is improved and the value of power difference of each output port is also significantly decreased. The maximum of power difference between four output ports is about 6.2%; however, the minimum value is only 0.6% or so. Moreover, the average power difference of four output ports is lower than 10% for TE polarization light over the 10 nm wavelength bandwidth centered at 1.54 μm. In addition, the splitter structure has the best tolerance for grating fabrication with deviations of grating depth 90 nm.

  20. Damage thresholds for blaze diffraction gratings and grazing incidence optics at an X-ray free-electron laser.

    Science.gov (United States)

    Krzywinski, Jacek; Conley, Raymond; Moeller, Stefan; Gwalt, Grzegorz; Siewert, Frank; Waberski, Christoph; Zeschke, Thomas; Cocco, Daniele

    2018-01-01

    The Linac Coherent Light Source is upgrading its machine to high repetition rate and to extended ranges. Novel coatings, with limited surface oxidation, which are able to work at the carbon edge, are required. In addition, high-resolution soft X-ray monochromators become necessary. One of the big challenges is to design the mirror geometry and the grating profile to have high reflectivity (or efficiency) and at the same time survive the high peak energy of the free-electron laser pulses. For these reasons the experimental damage threshold, at 900 eV, of two platinum-coated gratings with different blazed angles has been investigated. The gratings were tested at 1° grazing incidence. To validate a model for which the damage threshold on the blaze grating can be estimated by calculating the damage threshold of a mirror with an angle of incidence identical to the angle of incidence on the grating plus the blaze angle, tests on Pt-coated substrates have also been performed. The results confirmed the prediction. Uncoated silicon, platinum and SiB 3 (both deposited on a silicon substrate) were also investigated. In general, the measured damage threshold at grazing incidence is higher than that calculated under the assumption that there is no energy transport from the volume where the photons are absorbed. However, it was found that, for the case of the SiB 3 coating, the grazing incidence condition did not increase the damage threshold, indicating that the energy transport away from the extinction volume is negligible.

  1. History of grating images

    Science.gov (United States)

    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.

  2. Low-temperature X-ray diffraction study of martensite lattice parameters in binary Ti-Ni alloys

    International Nuclear Information System (INIS)

    Prokoshkin, S.D.; Korotitskiy, A.V.; Gundyrev, V.M.; Zeldovich, V.I.

    2008-01-01

    Concentration and temperature dependency of the B19'-martensite lattice parameters (MLP) in binary Ti-Ni alloys as well as the effect of the structural state of a parent austenite on these parameters were studied using low-temperature X-ray diffraction analysis. The existence of a concentration dependence of the MLP found for the hyper-equiatomic nickel concentration range is proved for cryogenic temperature range and extended, at least, up to 51.2 at.% of nickel. Temperature dependency of MLP is observed in the studied nickel concentration range, and they are approximately the same for different alloys in the temperature range of stable martensite. During heating in the temperature range of the martensite existence, all parameters of the B19'-martensite monoclinic cell change towards the values of corresponding parameters of the austenite tetragonal cell with which they have 'genetic' relations. The maximum transformation lattice strain calculated at the martensite-start temperature of each alloy, and, hence, the resource of the recoverable strain, are higher for pre-equiatomic and equiatomic alloys than that for alloys in hyper-equiatomic nickel concentration range. For Ti-50.7 at.% Ni alloy, the lattice parameters of martensite formed from the austenite containing a well-developed dislocation substructure deviate from the corresponding lattice parameters of the quenched martensite formed from a low-dislocated recrystallized austenite. This distinction is a general feature for the alloys undergoing B2 → B19' and B2 → R → B19' martensitic transformations

  3. An efficient plane-grating monochromator based on conical diffraction for continuous tuning in the entire soft X-ray range including tender X-rays (2-8 keV).

    Science.gov (United States)

    Jark, Werner

    2016-01-01

    Recently it was verified that the diffraction efficiency of reflection gratings with rectangular profile, when illuminated at grazing angles of incidence with the beam trajectory along the grooves and not perpendicular to them, remains very high for tender X-rays of several keV photon energy. This very efficient operation of a reflection grating in the extreme off-plane orientation, i.e. in conical diffraction, offers the possibility of designing a conical diffraction monochromator scheme that provides efficient continuous photon energy tuning over rather large tuning ranges. For example, the tuning could cover photon energies from below 1000 eV up to 8 keV. The expected transmission of the entire instrument is high as all components are always operated below the critical angle for total reflection. In the simplest version of the instrument a plane grating is preceded by a plane mirror rotating simultaneously with it. The photon energy selection will then be made using the combination of a focusing mirror and exit slit. As is common for grating monochromators for soft X-ray radiation, the minimum spectral bandwidth is source-size-limited, while the bandwidth can be adjusted freely to any larger value. As far as tender X-rays (2-8 keV) are concerned, the minimum bandwidth is at least one and up to two orders of magnitude larger than the bandwidth provided by Si(111) double-crystal monochromators in a collimated beam. Therefore the instrument will provide more flux, which can even be increased at the expense of a bandwidth increase. On the other hand, for softer X-rays with photon energies below 1 keV, competitive relative spectral resolving powers of the order of 10000 are possible.

  4. Ultrabroadband TM reflection from high contrast grating: why?

    NARCIS (Netherlands)

    Gushchin, I.; Tishchenko, A.V.; Parriaux, O.; Hoekstra, Hugo

    2009-01-01

    A grating mode analysis of the unusually broadband TM reflection from a high contrast binary grating sheds light on the origin of this effect. This interpretation will be submitted to the workshop attendance.

  5. Holographic Gratings for Slow-Neutron Optics

    Science.gov (United States)

    Klepp, Juergen; Pruner, Christian; Tomita, Yasuo; Geltenbort, Peter; Drevenšek-Olenik, Irena; Gyergyek, Saso; Kohlbrecher, Joachim; Fally, Martin

    2012-01-01

    Recent progress in the development of holographic gratings for neutron-optics applications is reviewed. We summarize the properties of gratings recorded in deuterated (poly)methylmethacrylate, holographic polymer-dispersed liquid crystals and nanoparticle-polymer composites revealed by diffraction experiments with slow neutrons. Existing and anticipated neutron-optical instrumentations based on holographic gratings are discussed.

  6. A comparative study of the use of powder X-ray diffraction, Raman and near infrared spectroscopy for quantification of binary polymorphic mixtures of piracetam.

    Science.gov (United States)

    Croker, Denise M; Hennigan, Michelle C; Maher, Anthony; Hu, Yun; Ryder, Alan G; Hodnett, Benjamin K

    2012-04-07

    Diffraction and spectroscopic methods were evaluated for quantitative analysis of binary powder mixtures of FII(6.403) and FIII(6.525) piracetam. The two polymorphs of piracetam could be distinguished using powder X-ray diffraction (PXRD), Raman and near-infrared (NIR) spectroscopy. The results demonstrated that Raman and NIR spectroscopy are most suitable for quantitative analysis of this polymorphic mixture. When the spectra are treated with the combination of multiplicative scatter correction (MSC) and second derivative data pretreatments, the partial least squared (PLS) regression model gave a root mean square error of calibration (RMSEC) of 0.94 and 0.99%, respectively. FIII(6.525) demonstrated some preferred orientation in PXRD analysis, making PXRD the least preferred method of quantification. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Description of diffraction-grating experiments for photons and electrons in Feynman's spacetime formulation of quantum mechanics: the quantum origins of classical wave theories of light and massive particles

    Science.gov (United States)

    Field, J. H.

    2013-11-01

    The five laws of relativistic quantum mechanics, according to Feynman's path integral formulation, are concisely stated and applied to experiments. Reflection-diffraction-grating experiments for both photons and electrons are analysed, in particular, the Davisson-Germer experiment in which the wave-like property of electrons was first established. It is shown how classical, purely spatial, effective wave theories for both photons and electrons are predicted by the path integral formulation of quantum mechanics. The standard Copenhagen interpretation of wave mechanics is critically discussed in the light of the described experimental applications of the path integral formulation.

  8. Spherical grating spectrometers

    Science.gov (United States)

    O'Donoghue, Darragh; Clemens, J. Christopher

    2014-07-01

    We describe designs for spectrometers employing convex dispersers. The Offner spectrometer was the first such instrument; it has almost exclusively been employed on satellite platforms, and has had little impact on ground-based instruments. We have learned how to fabricate curved Volume Phase Holographic (VPH) gratings and, in contrast to the planar gratings of traditional spectrometers, describe how such devices can be used in optical/infrared spectrometers designed specifically for curved diffraction gratings. Volume Phase Holographic gratings are highly efficient compared to conventional surface relief gratings; they have become the disperser of choice in optical / NIR spectrometers. The advantage of spectrometers with curved VPH dispersers is the very small number of optical elements used (the simplest comprising a grating and a spherical mirror), as well as illumination of mirrors off axis, resulting in greater efficiency and reduction in size. We describe a "Half Offner" spectrometer, an even simpler version of the Offner spectrometer. We present an entirely novel design, the Spherical Transmission Grating Spectrometer (STGS), and discuss exemplary applications, including a design for a double-beam spectrometer without any requirement for a dichroic. This paradigm change in spectrometer design offers an alternative to all-refractive astronomical spectrometer designs, using expensive, fragile lens elements fabricated from CaF2 or even more exotic materials. The unobscured mirror layout avoids a major drawback of the previous generation of catadioptric spectrometer designs. We describe laboratory measurements of the efficiency and image quality of a curved VPH grating in a STGS design, demonstrating, simultaneously, efficiency comparable to planar VPH gratings along with good image quality. The stage is now set for construction of a prototype instrument with impressive performance.

  9. The grating as an accelerating structure

    International Nuclear Information System (INIS)

    Fernow, R.C.

    1991-02-01

    This report considers the use of a diffraction grating as an accelerating structure for charged particle beams. We examine the functional dependence of the electromagnetic fields above the surface of a grating. Calculations are made of the strength of the accelerating modes for structures with π and 2π phase advance per period and for incident waves polarized with either the E or H vector along the grooves of the grating. We consider examples of using gratings in a laser linac and in a grating lens. We also briefly examine previous results published about this subject. 36 refs

  10. Investigation of diffractive optical element femtosecond laser machining

    Energy Technology Data Exchange (ETDEWEB)

    Chabrol, Grégoire R., E-mail: g.chabrol@ecam-strasbourg.eu [ECAM Strasbourg-Europe, Espace Européen de l’entreprise, 2, rue de Madrid – 67300 SCHILTIGHEIM, CS. 20013, 67012 Strasbourg CEDEX (France); Laboratoire des Sciences de l’Ingénieur, de l’Informatique et de l’Imagerie (ICube), UDS-CNRS, UMR 7357, 300 bld Sébastien Brant, CS 10413, 67412 Illkirch cedex (France); Ciceron, Adline [ECAM Strasbourg-Europe, Espace Européen de l’entreprise, 2, rue de Madrid – 67300 SCHILTIGHEIM, CS. 20013, 67012 Strasbourg CEDEX (France); Laboratoire des Sciences de l’Ingénieur, de l’Informatique et de l’Imagerie (ICube), UDS-CNRS, UMR 7357, 300 bld Sébastien Brant, CS 10413, 67412 Illkirch cedex (France); Twardowski, Patrice; Pfeiffer, Pierre [Laboratoire des Sciences de l’Ingénieur, de l’Informatique et de l’Imagerie (ICube), UDS-CNRS, UMR 7357, 300 bld Sébastien Brant, CS 10413, 67412 Illkirch cedex (France); Télécom Physique Strasbourg – Pôle API – 300 Bd Sébastien Brant – CS 10413, Illkirch Graffenstaden F 67400 (France); and others

    2016-06-30

    Highlights: • A method for rapid manufacturing of optical diffractive element in BK7 is proposed. • A binary grating in BK7 was successfully machined by femtosecond laser pulses. • Process relying on nonlinear absorption in the dielectric due to photoionization. • The binary grating was analysed by SEM and interferometric microscopy. • Simulations by Fourier modal method supported the measured diffractive efficiency. - Abstract: This paper presents an explorative study on the machining of diffractive optical elements (DOEs) in transparent materials using a femtosecond laser source. A simple form of DOE, a binary phase grating with a period of 20.85 μm (σ = 0.5 μm), a groove depth and width of 0.7 μm (σ = 0.2 μm) and 8.8 μm (σ = 0.5 μm) respectively, was successfully machined in BK7. The topographic characteristics were measured by white light interferometry and scanning electron microscopy (SEM). The processing was carried out on high precision stages with an ultrafast fibre laser (350 fs) emitting a 343 nm pulse focused onto the sample with a stationary microscope objective. A diffracted efficiency of 27%, obtained with a spectro goniometer, was corroborated by the theoretical results obtained by the Fourier modal method (FMM), taking into account the measured topographic values. These encouraging results demonstrate that high-speed femtosecond laser manufacturing of DOE in bulk glasses can be achieved, opening the way to rapid prototyping of multi-layered-DOEs.

  11. Programmable spectral design and the binary supergrating

    Science.gov (United States)

    Levner, Daniel

    Spectral operations such as wavelength selection, power level manipulation, and chromatic dispersion control are key to many processes in optical telecommunication, spectroscopy, and sensing. In their simplest forms, these functions can be performed using a number of successful devices such as the Fraunhofer ("diffraction") grating, Bragg grating, thin-film filter (TFF), and dispersion-compensating fiber (DCF). More complicated manipulations, however, often require either problematic cascades of many simple elements, the use of custom technologies that offer little adjustment, or the implementation of fully programmable devices, which allow for the desired spectral function to be synthesized ab initio. Here, I present the Binary Supergrating (BSG), a novel technology that permits the programmable and near-arbitrary control of optical amplitude and phase using a simple, robust and practical form. This guided-wave form consists of an aperiodic sequence of binary elements; the sequence, determined through the process of BSG synthesis, encodes an optical program that defines device functionality. The ability to derive optical programs that address broad spectral demands is central to the BSG's extensive capabilities. In consequence, I present a powerful approach to synthesis that exploits existing knowledge in the design of "analog" gratings. This approach is based on a two-step process, which first derives an analog diffractive structure using the best available methods and then transforms it into binary form. Accordingly, I discuss the notion of diffractive structure transformation and introduce the principle of key information. I identify such key information and illustrate its application in grating quantizers based on an atypical form of Delta-Sigma modulation. As a digital approach to spectral engineering, the BSG presents many of the same advantages offered by the digital approach to electronic signal processing (DSP) over its analog predecessors. As such, it

  12. Metrology measurements for large-aperture VPH gratings

    Science.gov (United States)

    Zheng, Jessica R.; Gers, Luke; Heijmans, Jeroen

    2013-09-01

    The High Efficiency and Resolution Multi Element Spectrograph (HERMES) for the Australian Astronomical Observatory (AAO) uses four large aperture, high angle of incidence volume phase holographic gratings (VPHG) for high resolution `Galactic archaeology' spectroscopy. The large clear aperture, the high diffraction efficiency, the line frequency homogeneity, and mosaic alignment made manufacturing and testing challenging. We developed new metrology systems at the AAO to verify the performance of these VPH gratings. The measured diffraction efficiencies and line frequency of the VPH gratings received so far meet the vendor's provided data. The wavefront quality for the Blue VPH grating is good but the Green and Red VPH gratings need to be post polishing.

  13. Talbot effect of the defective grating in deep Fresnel region

    Science.gov (United States)

    Teng, Shuyun; Wang, Junhong; Zhang, Wei; Cui, Yuwei

    2015-02-01

    Talbot effect of the grating with different defect is studied theoretically and experimentally in this paper. The defects of grating include the loss of the diffraction unit, the dislocation of the diffraction unit and the modulation of the unit separation. The exact diffraction distributions of three kinds of defective gratings are obtained according to the finite-difference time-domain (FDTD) method. The calculation results show the image of the missing or dislocating unit appears at the Talbot distance (as mentioned in K. Patorski Prog. Opt., 27, 1989, pp.1-108). This is the so-called self-repair ability of grating imaging. In addition, some more phenomena are discovered. The loss or the dislocation of diffraction unit causes the diffraction distortion within a certain radial angle. The regular modulation of unit separation changes the original diffraction, but the new periodicity of the diffraction distribution rebuilds. The self-imaging of grating with smaller random modulation still keeps the partial self-repair ability, and yet this characteristic depends on the modulation degree of defective grating. These diffraction phenomena of the defective gratings are explained by use of the diffraction theory of grating. The practical experiment is also performed and the experimental results confirm the theoretic predictions.

  14. New Constraints on the Geometry and Kinematics of Matter Surrounding the Accretion Flow in X-Ray Binaries from Chandra High-energy Transmission Grating X-Ray Spectroscopy

    Science.gov (United States)

    Tzanavaris, P.; Yaqoob, T.

    2018-03-01

    The narrow, neutral Fe Kα fluorescence emission line in X-ray binaries (XRBs) is a powerful probe of the geometry, kinematics, and Fe abundance of matter around the accretion flow. In a recent study it has been claimed, using Chandra High-Energy Transmission Grating (HETG) spectra for a sample of XRBs, that the circumnuclear material is consistent with a solar-abundance, uniform, spherical distribution. It was also claimed that the Fe Kα line was unresolved in all cases by the HETG. However, these conclusions were based on ad hoc models that did not attempt to relate the global column density to the Fe Kα line emission. We revisit the sample and test a self-consistent model of a uniform, spherical X-ray reprocessor against HETG spectra from 56 observations of 14 Galactic XRBs. We find that the model is ruled out in 13/14 sources because a variable Fe abundance is required. In two sources a spherical distribution is viable, but with nonsolar Fe abundance. We also applied a solar-abundance Compton-thick reflection model, which can account for the spectra that are inconsistent with a spherical model, but spectra with a broader bandpass are required to better constrain model parameters. We also robustly measured the velocity width of the Fe Kα line and found FWHM values of up to ∼5000 km s‑1. Only in some spectra was the Fe Kα line unresolved by the HETG.

  15. An X-ray grazing incidence phase multilayer grating

    CERN Document Server

    Chernov, V A; Mytnichenko, S V

    2001-01-01

    An X-ray grazing incidence phase multilayer grating, representing a thin grating placed on a multilayer mirror, is proposed. A high efficiency of grating diffraction can be obtained by the possibility of changing the phase shift of the wave diffracted from the multilayer under the Bragg and total external reflection conditions. A grazing incidence phase multilayer grating consisting of Pt grating stripes on a Ni/C multilayer and optimized for the hard X-ray range was fabricated. Its diffraction properties were studied at photon energies of 7 and 8 keV. The obtained maximum value of the diffraction efficiency of the +1 grating order was 9% at 7 keV and 6.5% at 8 keV. The data obtained are in a rather good accordance with the theory.

  16. Astronomical large Ge immersion grating by Canon

    Science.gov (United States)

    Sukegawa, Takashi; Suzuki, Takeshi; Kitamura, Tsuyoshi

    2016-07-01

    Immersion grating is a powerful optical device for thee infrared high-resolution spectroscope. Germanium (GGe) is the best material for a mid-infrared immersion grating because of Ge has very large reflective index (n=4.0). On the other hands, there is no practical Ge immersion grating under 5umm use. It was very difficult for a fragile IR crystal to manufacture a diffraction grating precisely. Our original free-forming machine has accuracy of a few nano-meter in positioning and stability. We already fabricated the large CdZnTe immersion grating. (Sukegawa et al. (2012), Ikeda et al. (2015)) Wee are developing Ge immersion grating that can be a good solution for high-resolution infrared spectroscopy with the large ground-based/space telescopes. We succeeded practical Ge immersion grating with the grooved area off 75mm (ruled direction) x 119mm (grove width) and the blaze angle of 75 degrees. Our astronomical large Ge immersion grating has the grooved area of 155mm (ruled direction) x 41mmm (groove width) and groove pitch off 91.74um. We also report optical performance of astronomical large Ge immersion grating with a metal coating on the diffraction surface.

  17. Linear Fresnel Spectrometer Chip with Gradient Line Grating

    Science.gov (United States)

    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.

  18. Diffractive Optics for Gravitational Wave Detectors

    International Nuclear Information System (INIS)

    Bunkowski, A; Burmeister, O; Clausnitzer, T; Kley, E-B; Tuennermann, A; Danzmann, K; Schnabel, R

    2006-01-01

    All-reflective interferometry based on nano-structured diffraction gratings offers new possibilities for gravitational wave detection. We investigate an all-reflective Fabry-Perot interferometer concept in 2nd order Littrow mount. The input-output relations for such a resonator are derived treating the grating coupler by means of a scattering matrix formalism. A low loss dielectric reflection grating has been designed and manufactured to test the properties of such a grating cavity

  19. Genetic local search algorithm for optimization design of diffractive optical elements.

    Science.gov (United States)

    Zhou, G; Chen, Y; Wang, Z; Song, H

    1999-07-10

    We propose a genetic local search algorithm (GLSA) for the optimization design of diffractive optical elements (DOE's). This hybrid algorithm incorporates advantages of both genetic algorithm (GA) and local search techniques. It appears better able to locate the global minimum compared with a canonical GA. Sample cases investigated here include the optimization design of binary-phase Dammann gratings, continuous surface-relief grating array generators, and a uniform top-hat focal plane intensity profile generator. Two GLSA's whose incorporated local search techniques are the hill-climbing method and the simulated annealing algorithm are investigated. Numerical experimental results demonstrate that the proposed algorithm is highly efficient and robust. DOE's that have high diffraction efficiency and excellent uniformity can be achieved by use of the algorithm we propose.

  20. Optical Fiber Grating based Sensors

    DEFF Research Database (Denmark)

    Michelsen, Susanne

    2003-01-01

    In this thesis differenct optical fiber gratings are used for sensor purposes. If a fiber with a core concentricity error (CCE) is used, a directional dependent bend sensor can be produced. The CCE direction can be determined by means of diffraction. This makes it possible to produce long......-period gratings in a fiber with a CCE direction parallel or perpendicular to the writing direction. The maximal bending sensitivity is independent on the writing direction, but the detailed bending response is different in the two cases. A temperature and strain sensor, based on a long-period grating and two...... wavelength. It is shown that it is possible to tune and modulate a DFB fiber laser with both strain from a piezoelectric transducer and by temperature through resistive heating of a methal film. Both a chemical deposited silver layer and an electron-beam evaporation technique has been investigated, to find...

  1. Fiber Optic Bragg Gratings

    National Research Council Canada - National Science Library

    Battiato, James

    1998-01-01

    Coupled mode theory was used to model reflection fiber gratings. The effects of experimental parameters on grating characteristics were modeled for both uniform and non-uniform grating profiles using this approach...

  2. Neutron-optical gratings from nanoparticle-polymer composites

    Science.gov (United States)

    Klepp, J.; Pruner, C.; Ellabban, M. A.; Tomita, Y.; Lemmel, H.; Rauch, H.; Fally, M.

    2011-04-01

    The preparation of neutron-optical phase gratings with light-optical holography is reviewed. We compare the relevant concepts of: (i) Kogelnik's theory for Bragg diffraction of light by thick volume gratings, which can be used to analyze holographic gratings with both light and neutrons, and (ii) the dynamical theory of neutron diffraction. Without going into mathematical detail, we intend to illuminate their correspondence. The findings are illustrated by analyzing data obtained from reconstruction of nanoparticle holographic gratings with both light and neutrons.

  3. Nonlinear diffraction from a virtual beam

    DEFF Research Database (Denmark)

    Saltiel, Solomon M.; Neshev, Dragomir N.; Krolikowski, Wieslaw

    2010-01-01

    We observe experimentally a novel type of nonlinear diffraction in the process of two-wave mixing on a nonlinear quadratic grating.We demonstrate that when the nonlinear grating is illuminated simultaneously by two noncollinear beams, a second-harmonic diffraction pattern is generated by a virtual...... beam propagating along the bisector of the two pump beams. The observed iffraction phenomena is a purely nonlinear effect that has no analogue in linear diffraction...

  4. Compact high-resolution spectrometer using two plane gratings with triple dispersion.

    Science.gov (United States)

    Pang, Yajun; Zhang, Yinxin; Yang, Huaidong; Liu, Zeyang; Huang, Zhanhua; Jin, Guofan

    2018-03-05

    We demonstrate a compact high-resolution spectrometer scheme using two plane gratings. In this approach, the rays are first diffracted by a fixed grating, then incident on a rotating grating at the Littrow diffraction angle, and are finally diffracted and reflected back to the fixed grating again. Thus, triple dispersion (TD) occurs during measurement, increasing the resolution. The formulae of this compact high-resolution spectrometer are rigorously derived. A design simulation with two gratings of 1050 lines/mm is performed and discussed. In addition, a prototype of this spectrometer has been built and tested. Its spectral resolution reaches a precision of 36 pm.

  5. Talbot effect of grating with fractal rough edges

    International Nuclear Information System (INIS)

    Teng, Shuyun; Cui, Yuwei; Li, Zhong

    2016-01-01

    Since the random edges of practically manufactured grating can be described by the self-affine fractal model, this paper investigates theoretically Fresnel diffraction of grating with rough edges on the basis of the self-affine fractal theory and discusses the variation of the Talbot image of grating with the rough parameters of edges. The amplitude gratings with different rough edges are produced with the help of the correlation function of the random distribution. Then, simulations of the diffraction intensity distributions of rough gratings are performed, and the modulation effect of speckles on Talbot image are shown. In order to explain the variation of the Talbot image of grating with rough edges, the theoretical analysis of the Talbot effect of grating with rough edges is given according to the statistic optics theory. The presented approximate analytic expression of the average diffraction intensity indicates the relationship between the diffraction and rough parameters of grating edges. The conclusions of this paper are useful for evaluating the Talbot image of practical grating. (paper)

  6. Plasmonic Transmission Gratings – Fabrication and Characterization

    DEFF Research Database (Denmark)

    Sierant, Aleksandra; Jany, Benedykt; Bartoszek-Bober, Dobrosława

    realization is given by the use of a metallic diffraction grating, where the diffracted light couples to the SPP. Here, we propose metallic periodic transmission gratings, processed onto a glass substrate, with various periods and fill factors. The gratings are milled in a plain gold layer with a focused ion......Surface plasmon polaritons (SPPs) are collective electron oscillations, confined at metal-dielectric interfaces. Coupling incident photons to SPPs may lead to spectrally broad field enhancement and confinement below the diffraction limit [1]. This phenomenon facilitates various applications......) Simulations. [1] W. L. Barnes, A. Dereux, T. W. Ebbesen, Nature 424, 824–830 (2003) [2] X. D. Hoa, A. G. Kirk, M. Tabrizian, Biosensors and Bioelectronics, 23, 2, 151-160 (2007) [3] T. Kawalec, et al., Opt. Lett. 39, 2932 (2014)...

  7. Photon diffraction

    Science.gov (United States)

    Hodge, John

    2009-11-01

    In current light models, a particle-like model of light is inconsistent with diffraction observations. A model of light is proposed wherein photon inferences are combined with the cosmological scalar potential model (SPM). That the photon is a surface with zero surface area in the travel direction is inferred from the Michelson-Morley experiment. That the photons in slits are mathematically treated as a linear antenna array (LAA) is inferred from the comparison of the transmission grating interference pattern and the single slit diffraction pattern. That photons induce a LAA wave into the plenum is inferred from the fractal model. Similarly, the component of the photon (the hod) is treated as a single antenna radiating a potential wave into the plenum. That photons are guided by action on the surface of the hod is inferred from the SPM. The plenum potential waves are a real field (not complex) that forms valleys, consistent with the pilot waves of the Bohm interpretation of quantum mechanics. Therefore, the Afshar experiment result is explained, supports Bohm, and falsifies Copenhagen. The papers may be viewed at http://web.citcom.net/˜scjh/.

  8. Modern Theory of Gratings Resonant Scattering: Analysis Techniques and Phenomena

    CERN Document Server

    Sirenko, Yuriy K

    2010-01-01

    Diffraction gratings are one of the most popular objects of analysis in electromagnetic theory. The requirements of applied optics and microwave engineering lead to many new problems and challenges for the theory of diffraction gratings, which force us to search for new methods and tools for their resolution. In Modern Theory of Gratings, the authors present results of the electromagnetic theory of diffraction gratings that will constitute the base of further development of this theory, which meet the challenges provided by modern requirements of fundamental and applied science. This volume covers: spectral theory of gratings (Chapter 1) giving reliable grounds for physical analysis of space-frequency and space-time transformations of the electromagnetic field in open periodic resonators and waveguides; authentic analytic regularization procedures (Chapter 2) that, in contradistinction to the traditional frequency-domain approaches, fit perfectly for the analysis of resonant wave scattering processes; paramet...

  9. Grism and immersion grating for space telescope

    Science.gov (United States)

    Ebizuka, Noboru; Oka, Kiko; Yamada, Akiko; Ishikawa, Mami; Kashiwagi, Masako; Kodate, Kashiko; Hirahara, Yasuhiro; Sato, Shuji; Kawabata, Koji S.; Wakaki, Moriaki; Morita, Shin-ya; Simizu, Tomoyuki; Yin, Shaohui; Omori, Hitoshi; Iye, Masanori

    2017-11-01

    The grism is a versatile dispersion element for an astronomical instrument ranging from ultraviolet to infrared. Major benefit of using a grism in a space application, instead of a reflection grating, is the size reduction of optical system because collimator and following optical elements could locate near by the grism. The surface relief (SR) grism is consisted a transmission grating and a prism, vertex angle of which is adjusted to redirect the diffracted beam straight along the direct vision direction at a specific order and wavelength. The volume phase holographic (VPH) grism consists a thick VPH grating sandwiched between two prisms, as specific order and wavelength is aligned the direct vision direction. The VPH grating inheres ideal diffraction efficiency on a higher dispersion application. On the other hand, the SR grating could achieve high diffraction efficiency on a lower dispersion application. Five grisms among eleven for the Faint Object Camera And Spectrograph (FOCAS) of the 8.2m Subaru Telescope with the resolving power from 250 to 3,000 are SR grisms fabricated by a replication method. Six additional grisms of FOCAS with the resolving power from 3,000 to 7,000 are VPH grisms. We propose "Quasi-Bragg grism" for a high dispersion spectroscopy with wide wavelength range. The germanium immersion grating for instance could reduce 1/64 as the total volume of a spectrograph with a conventional reflection grating since refractive index of germanium is over 4.0 from 1.6 to 20 μm. The prototype immersion gratings for the mid-InfraRed High dispersion Spectrograph (IRHS) are successfully fabricated by a nano-precision machine and grinding cup of cast iron with electrolytic dressing method.

  10. Holographic gratings in photorefractive polymers without external electric field

    DEFF Research Database (Denmark)

    Kukhtarev, N.; Lyuksyutov, S.; Buchhave, Preben

    1997-01-01

    Using anomalous large diffusion we report a recording of reflection type gratings in a PVK-based photorefractive polymer without any external electric field. The diffraction efficiency of the gratings was measured to be 7%. An efficient modulation of beams during two-beam coupling up to 12...

  11. Pd grating obtained by direct micromolding for use in high resolution ...

    Indian Academy of Sciences (India)

    vity employing few tens of micron sized diffraction gratings. The binding ability of various analytes with the molecules of interest has been accessed using in situ assembled diffrac- tion gratings where thickness variation of the grating and changes in refractive index were studied (Goh et al 2005). In this context, Acharya et al ...

  12. Absolute determination by X-ray diffraction of a binary or ternary mixture: nickel oxide and fluoride in a nickel powder (1960)

    International Nuclear Information System (INIS)

    Charpin, P.; Hauptman, A.

    1960-01-01

    The method employed is based upon the comparison between computed and measured intensities for conveniently selected X-Ray diffraction lines of each component of the powder. Care must be taken to allow for absorption, both inside each grain and in overall sample. This method has been applied to the determination of nickel oxide and fluoride in a nickel powder. (author) [fr

  13. Bragg Fibers with Soliton-like Grating Profiles

    Directory of Open Access Journals (Sweden)

    Bugaychuk S.

    2016-01-01

    Full Text Available Nonlinear dynamical system corresponding to the optical holography in a nonlocal nonlinear medium with dissipation contains stable localized spatio-temporal states, namely the grid dissipative solitons. These solitons display a non-uniform profile of the grating amplitude, which has the form of the dark soliton in the reflection geometry. The transformation of the grating amplitude gives rise many new atypical effects for the beams diffracted on such grating, and they are very suitable for the fiber Brass gratings. The damped nonlinear Schrodinger equation is derived that describes the properties of the grid dissipative soliton.

  14. Thin film coated submicron gratings: theory, design, fabrication and application

    Energy Technology Data Exchange (ETDEWEB)

    Heine, C.

    1996-12-31

    The realization of new applications of submicron grating structures requires efficient theoretical methods and elaborate fabrication techniques. In this work rigorous diffraction theory for one-dimensional gratings has been investigated and optimization techniques, based on methods used in thin film optics, have been developed. Submicron gratings embossed in polycarbonate have been fabricated and characterized. This includes transmission measurements which are in good agreement with theoretical calculations. Designs for a wide range of optical filters, which lead to improved optical and mechanical properties, are presented. This has been demonstrated for broadband antireflection structures for solar energy applications, based on MgF{sub 2}-coated gratings. (author) figs., tabs., refs.

  15. Disorder effects in subwavelength grating metamaterial waveguides

    Czech Academy of Sciences Publication Activity Database

    Ortega-Moñux, A.; Čtyroký, Jiří; Cheben, P.; Schmid, J. H.; Wang, S.; Molina-Fernández, I.; Halíř, R.

    2017-01-01

    Roč. 25, č. 11 (2017), s. 12222-12236 ISSN 1094-4087 R&D Projects: GA ČR(CZ) GA16-00329S Institutional support: RVO:67985882 Keywords : Subwavelength grating * Integrated photonics * Diffraction effects Subject RIV: BH - Optics, Masers, Lasers OBOR OECD: Optics (including laser optics and quantum optics) Impact factor: 3.307, year: 2016

  16. Use of savart plates in grating interferometers.

    Science.gov (United States)

    Peek, T H

    1971-05-01

    An analysis is given of Savart plates for arbitrary angles between the optic axis and the plate normal. Conoscopic interference patterns of thin Savart plates cut nearly parallel to the optic axis are shown and the use of such plates combined with diffraction gratings is discussed.

  17. Disorder effects in subwavelength grating metamaterial waveguides

    Czech Academy of Sciences Publication Activity Database

    Ortega-Moñux, A.; Čtyroký, Jiří; Cheben, P.; Schmid, J. H.; Wang, S.; Molina-Fernández, I.; Halíř, R.

    2017-01-01

    Roč. 25, č. 11 (2017), s. 12222-12236 ISSN 1094-4087 R&D Projects: GA ČR(CZ) GA16-00329S Institutional support: RVO:67985882 Keywords : Subwavelength grating * Integrated photonics * Diffraction effect s Subject RIV: BH - Optics, Masers, Lasers OBOR OECD: Optics (including laser optics and quantum optics) Impact factor: 3.307, year: 2016

  18. Effective length of short Fabry-Perot cavity formed by uniform fiber Bragg gratings.

    Science.gov (United States)

    Barmenkov, Yuri O; Zalvidea, Dobryna; Torres-Peiró, Salvador; Cruz, Jose L; Andrés, Miguel V

    2006-07-10

    In this paper, we describe the properties of Fabry-Perot fiber cavity formed by two fiber Bragg gratings in terms of the grating effective length. We show that the grating effective length is determined by the group delay of the grating, which depends on its diffraction efficiency and physical length. We present a simple analytical formula for calculation of the effective length of the uniform fiber Bragg grating and the frequency separation between consecutive resonances of a Fabry-Perot cavity. Experimental results on the cavity transmission spectra for different values of the gratings' reflectivity support the presented theory.

  19. Electromagnetically induced two-dimensional grating assisted by incoherent pump

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yu-Yuan; Liu, Zhuan-Zhuan; Wan, Ren-Gang, E-mail: wrg@snnu.edu.cn

    2017-04-25

    We propose a scheme for realizing electromagnetically induced two-dimensional grating in a double-Λ system driven simultaneously by a coherent field and an incoherent pump field. In such an atomic configuration, the absorption is suppressed owing to the incoherent pumping process and the probe can be even amplified, while the refractivity is mainly attributed to the dynamically induced coherence. With the help of a standing-wave pattern coherent field, we obtain periodically modulated refractive index without or with gain, and therefore phase grating or gain-phase grating which diffracts a probe light into high-order direction efficiently can be formed in the medium via appropriate manipulation of the system parameters. The diffraction efficiency attainable by the present gratings can be controlled by tuning the coherent field intensity or the interaction length. Hence, the two-dimensional grating can be utilized as all-optical splitter or router in optical networking and communication. - Highlights: • Two-dimensional grating is coherently induced in four-level atoms. • Phase and gain-phase gratings are obtained assisted by incoherent pump. • The diffraction power is improved due to the enhanced refraction modulation. • The gratings can be utilized as multi-channel all-optical splitter and router.

  20. Performance of volume phase holographic transmission grating recorded in DCG for PGP

    Science.gov (United States)

    Li, Ming; Tang, Minxue; Xia, Haohan; Fang, Chunhuan; Wu, Jianhong; Zhao, Xunjie

    2010-11-01

    The volume phase holographic (VPH) transmission grating recorded in dichromate gelatin (DCG) with a specific spectral coverage from 420 nm to 760 nm is designed for a novel prism-grating-prism imaging spectrometer. Based on the Rigorous Coupled-Wave Analysis, its performances are predicted and analyzed. The grating is manufactured and its properties are measured experimentally. The diffraction efficiency over the spectral range, the bandwidth, and the angular selectivity of the grating is measured, analyzed and compared with that of the theoretical ones. The results show that by adjusting and controlling the preparation conditions of DCG plates, the exposure time and the post-processing technique of the grating, the VPH transmission grating with high diffraction efficiency approximate to the design requirement can be obtained. The measured peak diffraction efficiency reaches nearly 85% at central wavelength of 590 nm while the average diffraction efficiency is larger than 75% over the required spectral range from 420 nm to 760 nm.

  1. Deformable silicone grating fabricated with a photo-imprinted polymer mold

    Science.gov (United States)

    Yamada, Itsunari; Nishii, Junji; Saito, Mitsunori

    2014-01-01

    A tunable transmission grating was fabricated by molding a silicone elastomer (polydimethylsiloxane). Its optical characteristics were then evaluated during compression. For fabrication, a glass plate with a photoimprinted polymer grating film was used as a mold. Both the grating period and diffraction transmittance of the molded elastomer were functions of the compressive stress. The grating period changed from 3.02 to 2.86 μm during compressing the elastomer in the direction perpendicular to the grooves.

  2. Fiber facet gratings for high power fiber lasers

    Science.gov (United States)

    Vanek, Martin; Vanis, Jan; Baravets, Yauhen; Todorov, Filip; Ctyroky, Jiri; Honzatko, Pavel

    2017-12-01

    We numerically investigated the properties of diffraction gratings designated for fabrication on the facet of an optical fiber. The gratings are intended to be used in high-power fiber lasers as mirrors either with a low or high reflectivity. The modal reflectance of low reflectivity polarizing grating has a value close to 3% for TE mode while it is significantly suppressed for TM mode. Such a grating can be fabricated on laser output fiber facet. The polarizing grating with high modal reflectance is designed as a leaky-mode resonant diffraction grating. The grating can be etched in a thin layer of high index dielectric which is sputtered on fiber facet. We used refractive index of Ta2O5 for such a layer. We found that modal reflectance can be close to 0.95 for TE polarization and polarization extinction ratio achieves 18 dB. Rigorous coupled wave analysis was used for fast optimization of grating parameters while aperiodic rigorous coupled wave analysis, Fourier modal method and finite difference time domain method were compared and used to compute modal reflectance of designed gratings.

  3. Multiorder nonlinear diffraction in frequency doubling processes

    DEFF Research Database (Denmark)

    Saltiel, Solomon M.; Neshev, Dragomir N.; Krolikowski, Wieslaw

    2009-01-01

    We analyze experimentally light scattering from 2 nonlinear gratings and observe two types of second-harmonic frequency-scattering processes. The first process is identified as Raman–Nath type nonlinear diffraction that is explained by applying only transverse phase-matching conditions. The angular...... position of this type of diffraction is defined by the ratio of the second-harmonic wavelength and the grating period. In contrast, the second type of nonlinear scattering process is explained by the longitudinal phase matching only, being insensitive to the nonlinear grating...

  4. Novel gratings for next-generation instruments of astronomical observations

    Science.gov (United States)

    Ebizuka, N.; Okamoto, T.; Takeda, M.; Hosobata, T.; Yamagata, Y.; Sasaki, M.; Uomoto, M.; Shimatsu, T.; Sato, S.; Hashimoto, N.; Tanaka, I.; Hattori, T.; Ozaki, S.; Aoki, W.

    2017-05-01

    We will introduce current status of development of a birefringence volume phase holographic (B-VPH) grating, volume binary (VB) grating and reflector facet transmission (RFT) grating developing as the novel dispersive optical element for astronomical instruments for the 8.2m Subaru Telescope, for next generation 30 m class huge ground-based telescopes and for next generation large space-bone telescopes. We will also introduce a hybrid grism developed for MOIRCS (Multi-Object InfraRed Camera and Spectrograph) of the Subaru Telescope and a quasi-Bragg (QB) immersion grating. Test fabrication of B-VPH gratings with a liquid crystal (LC) of UV curable and normal LCs or a resin of visible light curable are performed. We successfully fabricated VB gratings of silicon as a mold with ridges of a high aspect ratio by means of the cycle etching process, oxidation and removal of silicon oxide. The RFT grating which is a surface-relief (SR) transmission grating with sawtooth shaped ridges of an acute vertex angle. The hybrid grism, as a prototype of the RFT grating, combines a high-index prism and SR transmission grating with sawtooth shape ridges of an acute vertex angle. The mold of the SR grating for the hybrid grism on to a work of Ni-P alloy of non-electrolysic plating successfully fabricated by using our ultra-precision machine and a single-crystal diamond bite. The QB immersion grating was fabricated by a combination of an inclined QB grating, Littrow prism and surface reflection mirror.

  5. Neutron Diffraction Measurements and First Principles Study of Thermal Motion of Atoms in Select M_{n+1}AX_n and Binary MX Transition Metal Carbide Phases

    OpenAIRE

    Lane, Nina J.; Vogel, Sven C.; Hug, Gilles; Togo, Atsushi; Chaput, Laurent; Hultman, Lars; Barsoum, Michel W.

    2012-01-01

    Herein, we compare the thermal vibrations of atoms in select ternary carbides with the formula Mn+1AXn ("MAX phases," M = Ti, Cr; A = Al, Si, Ge; X = C, N) as determined from first principles phonon calculations to those obtained from high-temperature neutron powder diffraction studies. The transition metal carbides TiC, TaC, and WC are also studied to test our methodology on simpler carbides. Good qualitative and quantitative agreement is found between predicted and experimental values for t...

  6. Lens gratings for dose optimization of medical X-ray phase contrast imaging.

    Science.gov (United States)

    Preusche, Oliver

    2016-11-14

    A novel way to build arrays of X-ray lenslets is proposed for use in medical imaging, in particular for X-ray phase contrast imaging. Focusing on Talbot-Lau interferometers, this work is about patient dose reduction, especially for design energies above 50 keV. A low dose poses a fabrication problem, because it requires an analyzer grating which is both fine and high: It has to be fine for a good angular sensitivity. It has to be high to absorb well. However, gratings can currently be built either fine or high. The proposed solution is to use a fine novel lens grating in front of a high analyzer grating: The lens grating uses lenslets to combine fine fringes into wider strips. This coarser pattern is then analyzed by a high grating. Regular binary production processes are sufficient to build lens gratings. Simulation-based results show that lens gratings can save dose with no impact on reconstructed images.

  7. An ultra-high-vacuum multiple grating chamber and scan drive with improved grating change

    International Nuclear Information System (INIS)

    Hulbert, S.L.; Holly, D.J.; Middleton, F.H.; Wallace, D.J.; Wisconsin Univ., Stoughton, WI; Wisconsin Univ., Stoughton, WI

    1989-01-01

    We describe a new grating chamber and scan drive which has been designed, built, and tested by Physical Sciences Laboratory of the University of Wisconsin for the new high flux, high-resolution spectroscopy branch line of the TOK hybrid wiggler/undulator on the NSLS VUV ring. The chamber will contain spherical gratings to be used in the Spherical Grating Monochromator (SGM) configuration introduced by Chen and Sette. The grating chamber houses five 180 mm x 35 mm x 30 mm gratings capable of scanning a range of 12 degree (-14 degree to +8 degree with respect to the incoming beam direction) for VUV and soft X-ray diffraction. The gratings can be switched and precisely indexed while under ultra-high vacuum (UHV) at any scan angle and are mechanically isolated from the vacuum chamber to prevent inaccuracies due to chamber distortions. The gratings can separately be adjusted for height, yaw, pitch, and roll, with the latter three performed while in vacuo. The scan drive provides a resolution of 0.03 arc sec with linearity over the 12 degree range of ∼1.5 arc sec and absolute reproducibility of 1 arc sec. 5 refs., 5 figs

  8. Fast tunable blazed MEMS grating for external cavity lasers

    Science.gov (United States)

    Tormen, Maurizio; Niedermann, Philippe; Hoogerwerf, Arno; Shea, Herbert; Stanley, Ross

    2017-11-01

    Diffractive MEMS are interesting for a wide range of applications, including displays, scanners or switching elements. Their advantages are compactness, potentially high actuation speed and in the ability to deflect light at large angles. We have designed and fabricated deformable diffractive MEMS grating to be used as tuning elements for external cavity lasers. The resulting device is compact, has wide tunability and a high operating speed. The initial design is a planar grating where the beams are free-standing and attached to each other using leaf springs. Actuation is achieved through two electrostatic comb drives at either end of the grating. To prevent deformation of the free-standing grating, the device is 10 μm thick made from a Silicon on Insulator (SOI) wafer in a single mask process. At 100V a periodicity tuning of 3% has been measured. The first resonant mode of the grating is measured at 13.8 kHz, allowing high speed actuation. This combination of wide tunability and high operating speed represents state of the art in the domain of tunable MEMS filters. In order to improve diffraction efficiency and to expand the usable wavelength range, a blazed version of the deformable MEMS grating has been designed. A key issue is maintaining the mechanical properties of the original device while providing optically smooth blazed beams. Using a process based on anisotropic KOH etching, blazed gratings have been obtained and preliminary characterization is promising.

  9. Fabrication of low straylight holographic gratings for space applications

    NARCIS (Netherlands)

    Steiner, R.; Pesch, A.; Erdmann, L.H.; Burkhardt, M.; Gatto, A.; Wipf, R.; Diehl, T.; Vink, H.J.P.; Bosch, B.G. van den

    2013-01-01

    The main challenges of fabricating diffraction gratings for use in earth monitoring spectrometers are given by the requirements for low stray light, high diffraction efficiency and a low polarization sensitivity. Furthermore the use in space also requires a high environmental stability of these

  10. INSCRIPTION PROCESS RESEARCH AND OPTIMIZATION FOR SUPERIMPOSED FIBER BRAGG GRATINGS

    Directory of Open Access Journals (Sweden)

    Kirill A. Konnov

    2017-11-01

    Full Text Available Subject of Research. The paper presents the study of inscription process distinctive features for superimposed fiber Bragg gratings. We analyzed spectral characteristics changes of superposition segregated gratings that appear during inscription of subsequent diffraction structures over the first ones. Method. Superimposed fiber Bragg gratings inscription was carried out by means of Talbot interferometer. Excimer laser system Optosystems MOPA CL-7550 was used as a radiation source. It was operating on gas mixture KrF (radiation wavelength is equal to 248 nm. The phase mask with a 1000 nm period was implemented in the inscription scheme for laser beam amplitude separation. Fiber Bragg gratings were inscribed in anisotropic optical fiber with 12 mol.% of GeO2 in optical fiber core. Main Results. Samples of superimposed fiber Bragg gratings were obtained and their spectral characteristics were analyzed. We have studied the regularities of the change in the reflection coefficient and the central wavelength of the first grating of the superposition from the number of diffraction structures inscribed over it, the exposure time during the inscription, and the spectral interval between them. Based on the results obtained, recommendations are given for optimizing the superimposed fiber Bragg gratings inscription process. Practical Relevance. The obtained superimposed fiber Bragg gratings can be used in the manufacture of optical filters, sensors for simultaneous measurement of several parameters, as well as for multiplexing and demultiplexing signals in telecommunications.

  11. Controlled angular redirection of light via nanoimprinted disordered gratings

    DEFF Research Database (Denmark)

    Buss, Thomas; Teisseire, Jérémie; Mazoyer, Simon

    2013-01-01

    Enhanced control of diffraction through transparent substrates is achieved via disordered gratings in a silica sol–gel film. Tailoring the degree of disorder allows tuning of the diffractive behavior from discrete orders into broad distributions over large angular range. Gratings of optical quality...... are formed by silica sol–gel nanoimprint lithography and an optical setup for the measurement of continuous diffraction patterns is presented. Sound agreement is found between measurements and simulation, validating both the approach for redirection of light and the fabrication process. The disordered...

  12. White-Light Diffraction with a CD

    Science.gov (United States)

    Ivanov, Dragia Trifonov; Nikolaev, Stefan

    2010-01-01

    Various wave optics experiments can be carried out using an ordinary compact disc. The CD is suitable for use as a diffraction grating. For instance, a standard CD (700 MB) has 625 lines/mm. In this article, the authors describe two white-light diffraction demonstrations for a large audience, realizable using a CD (as reflection or transmission…

  13. Gain-phase grating based on spatial modulation of active Raman gain in cold atoms

    International Nuclear Information System (INIS)

    Kuang Shangqi; Jin Chunshui; Li Chun

    2011-01-01

    In order to obtain an atomic grating which can diffract light into the high-order directions more efficiently, a gain-phase grating (GPG) based on the spatial modulation of active Raman gain is theoretically presented. This grating is induced by a pump field and a standing wave in ultracold atoms, and it not only diffracts a weak probe field propagating along a direction normal to the standing wave into the high-order directions, but also amplifies the amplitude of the zero-order diffraction. In contrast with electromagnetically induced grating or electromagnetically induced phase grating, the GPG has larger diffraction efficiencies in the high-order directions. Hence it is more suitable to be utilized as an all-optical router in optical networking and communication.

  14. Molecular reorientation in cross polarization gratings formed in thin photoreactive-polymer-liquid-crystal films

    Energy Technology Data Exchange (ETDEWEB)

    Ono, Hiroshi [Department of Electrical Engineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka 940-2188 (Japan)], E-mail: onoh@nagaokaut.ac.jp; Hatayama, Akira; Emoto, Akira [Department of Electrical Engineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka 940-2188 (Japan); Kawatsuki, Nobuhiro [Department of Materials Science and Chemistry, Himeji Institute of Technology, 2167 Shosha, Himeji 671-2201 (Japan)

    2008-04-30

    We present the results from some experimental and theoretical studies aimed at revealing the mechanism leading to the diffraction properties of two-dimensional cross polarization gratings in photocrosslinkable polymer liquid crystals. Although the polarization gratings are overwritten at the same place, each polarization grating works independently in our material system. The above-mentioned characteristic of our cross polarization gratings originates in the grating formation mechanism in the photocrosslinkable polymer liquid crystals, in which the molecules in the solid-state polymeric materials are not reoriented during exposure and reorientation is generated during the annealing process after multiple exposure.

  15. Spatio-temporal modeling and optimization of a deformable-grating compressor for short high-energy laser pulses.

    Science.gov (United States)

    Qiao, J; Papa, J; Liu, X

    2015-10-05

    Monolithic large-scale diffraction gratings are desired to improve the performance of high-energy laser systems and scale them to higher energy, but the surface deformation of these diffraction gratings induce spatio-temporal coupling that is detrimental to the focusability and compressibility of the output pulse. A new deformable-grating-based pulse compressor architecture with optimized actuator positions has been designed to correct the spatial and temporal aberrations induced by grating wavefront errors. An integrated optical model has been built to analyze the effect of grating wavefront errors on the spatio-temporal performance of a compressor based on four deformable gratings. A 1.5-meter deformable grating has been optimized using an integrated finite-element-analysis and genetic-optimization model, leading to spatio-temporal performance similar to the baseline design with ideal gratings.

  16. Time-Grating for the Generation of STUD Pulse Trains

    Science.gov (United States)

    Zheng, Jun; Wang, Shi-Wei; Xu, Jian-Qiu

    2013-04-01

    Spike train of uneven duration or delay (STUD) pulses hold potential for laser-plasma interaction (LPI) control in laser fusion. The technique based on time grating is applied to generate an STUD pulse train. Time grating, a temporal analogy of the diffraction grating, can control the pulse width, shape, and repetition rate easily through the use of electro-optical devices. The pulse width and repetition rate are given by the modulation frequency and depth of the phase modulation function in theory and numerical calculation. The zero-chirped phase modulation is good for the compression effect of the time grating. A principle experiment of two pulses interfering is shown to verify the time grating function.

  17. Bragg gratings in Topas

    DEFF Research Database (Denmark)

    Zhang, C.; Webb, D.J.; Kalli, K.

    We report for the first time fibre Bragg grating inscription in microstructured optical fibre fabricated from Topas® cyclic olefin copolymer. The temperature sensitivity of the grating was studied revealing a positive Bragg wavelength shift of approximately 0.8 nmK-1,the largest sensitivity yet...

  18. Spherical grating based x-ray Talbot interferometry

    International Nuclear Information System (INIS)

    Cong, Wenxiang; Xi, Yan; Wang, Ge

    2015-01-01

    Purpose: Grating interferometry is a state-of-the-art x-ray imaging approach, which can acquire information on x-ray attenuation, phase shift, and small-angle scattering simultaneously. Phase-contrast imaging and dark-field imaging are very sensitive to microstructural variation and offers superior contrast resolution for biological soft tissues. However, a common x-ray tube is a point-like source. As a result, the popular planar grating imaging configuration seriously restricts the flux of photons and decreases the visibility of signals, yielding a limited field of view. The purpose of this study is to extend the planar x-ray grating imaging theory and methods to a spherical grating scheme for a wider range of preclinical and clinical applications. Methods: A spherical grating matches the wave front of a point x-ray source very well, allowing the perpendicular incidence of x-rays on the grating to achieve a higher visibility over a larger field of view than the planer grating counterpart. A theoretical analysis of the Talbot effect for spherical grating imaging is proposed to establish a basic foundation for x-ray spherical gratings interferometry. An efficient method of spherical grating imaging is also presented to extract attenuation, differential phase, and dark-field images in the x-ray spherical grating interferometer. Results: Talbot self-imaging with spherical gratings is analyzed based on the Rayleigh–Sommerfeld diffraction formula, featuring a periodic angular distribution in a polar coordinate system. The Talbot distance is derived to reveal the Talbot self-imaging pattern. Numerical simulation results show the self-imaging phenomenon of a spherical grating interferometer, which is in agreement with the theoretical prediction. Conclusions: X-ray Talbot interferometry with spherical gratings has a significant practical promise. Relative to planar grating imaging, spherical grating based x-ray Talbot interferometry has a larger field of view and

  19. Diffusion study in tailored gratings recorded in photopolymer glass with high refractive index species

    Science.gov (United States)

    Martínez-Matos, Óscar; Calvo, María L.; Rodrigo, José A.; Cheben, Pavel; del Monte, Francisco

    2007-10-01

    We report results on the temporal evolution of the diffraction efficiency of volume holographic gratings recorded in a photopolymer glass incorporating Zr-based high refractive index species (HRIS) at molecular level. We record high spatial frequency gratings in this material with diffraction efficiencies near 100%. A two-component diffusion model is introduced for the evolution of refractive index modulation in darkness. Diffusion parameters for the Zr-based HRIS and monomer components have been determined. Codirectional diffusion of both components is demonstrated. The results show the feasibility for tailoring in this photomaterial holographic gratings with high diffraction efficiency over a wide range of spatial frequencies.

  20. Water Vapor Sensors Based on the Swelling of Relief Gelatin Gratings

    Directory of Open Access Journals (Sweden)

    Sergio Calixto

    2015-01-01

    Full Text Available We report on a novel device to measure relative humidity. The sensor is based on surface diffraction gratings made of gelatin. This material swells and shrinks according to the content of water vapor in air. By sending a light beam to the grating, diffracted orders appear. Due to the gelatin swelling or shrinking, first order intensity changes according to the relative humidity. Calibration curves relating intensity versus relative humidity have been found. The fabrication process of diffraction gratings and the testing of the prototype sensing devices are described.

  1. Two-Dimensional Light Diffraction from an EPROM Chip

    Science.gov (United States)

    Ekkens, Tom

    2018-01-01

    In introductory physics classes, a laser pointer and a compact disc are all the items required to illustrate diffraction of light in a single dimension. If a two-dimensional diffraction pattern is desired, double axis diffraction grating material is available or a CCD sensor can be extracted from an unused electronics device. This article presents…

  2. Reflection performance research of grating with polarization independence based on a sandwiched structure

    Science.gov (United States)

    Pei, Hao; Wang, Bo; Zhu, Wenhua; Yin, Sufang; Chen, Li; Lei, Liang; Zhou, Jinyun

    2018-02-01

    The novel reflective grating was studied under Littrow incidence as one sort of high-efficiency optical element. A covering layer and a dielectric layer are employed in this structure to achieve higher efficiency and wider bandwidth. For the given wavelength of 1550 nm, by using two-beam-interference theory of modal method, duty cycle and period of grating can be calculated, where the physical essence of high efficiency in the first-order is well explained by the modal method. The other grating parameters are optimized by using rigorous coupled-wave analysis. The optimized grating has an appropriate aspect ratio and shows that diffraction efficiencies of TE and TM polarizations in the first-order are greater than 97%. Compared with the reported surface-relief high-efficiency grating, the diffraction efficiencies of the proposed grating for TE and TM polarizations can be greatly improved.

  3. Aluminum nitride grating couplers.

    Science.gov (United States)

    Ghosh, Siddhartha; Doerr, Christopher R; Piazza, Gianluca

    2012-06-10

    Grating couplers in sputtered aluminum nitride, a piezoelectric material with low loss in the C band, are demonstrated. Gratings and a waveguide micromachined on a silicon wafer with 600 nm minimum feature size were defined in a single lithography step without partial etching. Silicon dioxide (SiO(2)) was used for cladding layers. Peak coupling efficiency of -6.6 dB and a 1 dB bandwidth of 60 nm have been measured. This demonstration of wire waveguides and wideband grating couplers in a material that also has piezoelectric and elasto-optic properties will enable new functions for integrated photonics and optomechanics.

  4. Color multiplexing using directional holographic gratings and linear polarization

    Energy Technology Data Exchange (ETDEWEB)

    Lugo, L I; Rodriguez, A; Ramirez, G; Guel, S; Nunez, O F, E-mail: roca@cactus.iico.uaslp.mx [Instituto de Investigacion en Comunicacion Optica (IICO) Universidad Autonoma de San Luis Potosi, S.L.P. (UASLP) (Mexico)

    2011-01-01

    We propose a system of multiplexing and de-multiplexing, which uses a holographic diffraction grating to compel modulated light of different colors to be sent through an optical fiber. Diffraction gratings were fabricated specifically to pick the desired direction in which we wanted the light of different wavelengths to impinge the optic fiber, and also to be separated at the output. It was been found that the system preserves the polarization of light, which give us a one more freedom degree, allowing us to process twice the original information amount.

  5. Laser-induced grating in ZnO

    DEFF Research Database (Denmark)

    Ravn, Jesper N.

    1992-01-01

    A simple approach for the calculation of self-diffraction in a thin combined phase and amplitude grating is presented. The third order nonlinearity, the electron-hole recombination time, and the ambipolar diffusion coefficient in a ZnO crystal are measured by means of laser-induced self-diffracti......A simple approach for the calculation of self-diffraction in a thin combined phase and amplitude grating is presented. The third order nonlinearity, the electron-hole recombination time, and the ambipolar diffusion coefficient in a ZnO crystal are measured by means of laser-induced self...

  6. Continuously tunable pulsed Ti:Sa laser self-seeded by an extended grating cavity

    CERN Document Server

    Li, Ruohong; Rothe, Sebastian; Teigelhöfer, Andrea; Mostamand, Maryam

    2016-01-01

    A continuously tunable titanium:sapphire (Ti:Sa) laser self-seeded by an extended grating cavity was demonstrated and characterized. By inserting a partially reflecting mirror inside the cavity of a classic single-cavity grating laser, two oscillators are created: a broadband power oscillator, and a narrowband oscillator with a prism beam expander and a diffraction grating in Littrow configuration. By coupling the grating cavity oscillation into the power oscillator, a power-enhanced narrow-linewidth laser oscillation is achieved. Compared to the classic grating laser, this simple modification significantly increases the laser output power without considerably broadening the linewidth. With most of the oscillating laser power confined inside the broadband power cavity and lower power incident onto the grating, the new configuration also allows higher pump power, which is typically limited by the thermal deformation of the grating coating at high oscillation power.

  7. Neutron diffraction

    International Nuclear Information System (INIS)

    James, M.; Howard, C.J.; Kennedy, S.

    1999-01-01

    Diffraction methods, especially X-ray diffraction, are widely used in materials science. Neutron diffraction is in many ways similar to X-ray diffraction, but is also complementary to the X-ray technique so that in some cases it yields information not accessible using X-rays. Successes of neutron diffraction include the elucidation of the crystal structures of high temperature superconductors and materials that display colossal magnetoresistance, the phase analysis of zirconia engineering ceramics, in depth stress determination in composites, successful determination of the structures of metal hydrides, transition metal polymer complexes and the determination of magnetic structure. A brief description of current studies, using neutron diffraction is given

  8. Application of the method of auxiliary sources in optical diffraction microscopy

    DEFF Research Database (Denmark)

    Karamehmedovic, Mirza; Sørensen, Mads Peter; Hansen, Poul-Erik

    2010-01-01

    The Method of Auxiliary Sources is used for characterisation of grating defects. Grating profiles are characterised by best fit matching of a library of diffraction efficiencies with numerical simulated diffraction efficiencies with defects. It is shown that the presented method can solve the inv...... the inverse problem with an accuracy usually thought to require rigorous electromagnetic theories....

  9. MEMS-based tunable gratings and their applications

    Science.gov (United States)

    Yu, Yiting; Yuan, Weizheng; Qiao, Dayong

    2015-03-01

    The marriage of optics and MEMS has resulted in a new category of optical devices and systems that have unprecedented advantages compared with their traditional counterparts. As an important spatial light modulating technology, diffractive optical MEMS obtains a wide variety of successful commercial applications, e.g. projection displays, optical communication and spectral analysis, due to its features of highly compact, low-cost, IC-compatible, excellent performance, and providing possibilities for developing totally new, yet smart devices and systems. Three most successful MEMS diffraction gratings (GLVs, Polychromator and DMDs) are briefly introduced and their potential applications are analyzed. Then, three different MEMS tunable gratings developed by our group, named as micro programmable blazed gratings (μPBGs) and micro pitch-tunable gratings (μPTGs) working in either digital or analog mode, are demonstrated. The strategies to largely enhance the maximum blazed angle and grating period are described. Some preliminary application explorations based on the developed grating devices are also shown. For our ongoing research focus, we will further improve the device performance to meet the engineering application requirements.

  10. Pd grating obtained by direct micromolding for use in high resolution ...

    Indian Academy of Sciences (India)

    contact printing (Kane et al 1999), have been most commonly used to fabricate low cost diffraction gratings. Multiple beam interference (Konkola et al 2003) and electron beam lithography (Bhuvana and Kulkarni 2008) though have capability of ...

  11. Metrology of variable-line-spacing x-ray gratings using the APS Long Trace Profiler

    Science.gov (United States)

    Sheung, Janet; Qian, Jun; Sullivan, Joseph; Thomasset, Muriel; Manton, Jonathan; Bean, Sunil; Takacs, Peter; Dvorak, Joseph; Assoufid, Lahsen

    2017-09-01

    As resolving power targets have increased with each generation of beamlines commissioned in synchrotron radiation facilities worldwide, diffraction gratings are quickly becoming crucial optical components for meeting performance targets. However, the metrology of variable-line-spacing (VLS) gratings for high resolution beamlines is not widespread; in particular, no metrology facility at any US DOE facility is currently equipped to fully characterize such gratings. To begin to address this issue, the Optics Group at the Advanced Photon Source at Argonne, in collaboration with SOLEIL and with support from Brookhaven National Laboratory (BNL), has developed an alternative beam path addition to the Long Trace Profiler (LTP) at Argonne's Advanced Photon Source. This significantly expands the functionality of the LTP not only to measure mirrors surface slope profile at normal incidence, but also to characterize the groove density of VLS diffraction gratings in the Littrow incidence up to 79°, which covers virtually all diffraction gratings used at synchrotrons in the first order. The LTP light source is a 20mW HeNe laser, which yields enough signal for diffraction measurements to be performed on low angle blazed gratings optimized for soft X-ray wavelengths. We will present the design of the beam path, technical requirements for the optomechanics, and our data analysis procedure. Finally, we discuss challenges still to be overcome and potential limitations with use of the LTP to perform metrology on diffraction gratings.

  12. Reconfigurable terahertz grating with enhanced transmission of TE polarized light

    Directory of Open Access Journals (Sweden)

    J. W. He

    2017-07-01

    Full Text Available We demonstrate an optically reconfigurable grating with enhanced transmission of TE-polarized waves in the terahertz (THz waveband. This kind of grating is realized by projecting a grating image onto a thin Si wafer with a digital micromirror device (DMD. The enhanced transmission is caused by a resonance of the electromagnetic fields between the photoexcited strips. The position of the transmission peak shifts with the variation of the period and duty cycle of the photoinduced grating, which can be readily controlled by the DMD. Furthermore, a flattened Gaussian model was applied to describe the distribution of the photoexcited free carriers in the Si wafer, and the simulated transmittance spectra are shown to be in good agreement with the experimental results. In future, the photoexcited carriers could also be used to produce THz diffractive elements with reconfigurable functionality.

  13. Rigorous coupled-wave theory for lossy volume grating in Laue geometry X-ray spectroscopy

    OpenAIRE

    André, Jean-Michel; Le Guen, Karine; Jonnard, Philippe

    2014-01-01

    The rigorous coupled-wave analysis of grating diffraction initiated by Moharam and Gaylor [JOSA 71, 811 (1981)] has been extended to lossy media and Fourier gratings for Laue diffraction geometry. In the rigorous approach, the second derivatives of field amplitude in the wave propagation equation together with high-order wave Fourier components are kept and exact boundary conditions are implemented. The problem is reduced to a state differential equation formulated in a matrix form. The restr...

  14. Surface relief gratings in azobenzene supramolecular systems based on polyimides

    Science.gov (United States)

    Schab-Balcerzak, Ewa; Sobolewska, Anna; Stumpe, Joachim; Hamryszak, Lukasz; Bujak, Piotr

    2012-12-01

    The paper describes formation of new supramolecular azopolymers based on hydrogen bonds as perspective materials for laser induced surface relief gratings (SRGs) and for polarization gratings. Supramolecular films were built on the basis of hydrogen bonds between the functional groups of polymer and azobenzene derivatives, that is 4-[4-(3-hydroxypropyloxy)phenylazo]-pyridine and 4-[4-(6-hydroxyhexyloxy)phenylazo]pyridine. Polymers with imide rings, i.e., poly(esterimide)s and poly(etherimide)s, with phenolic hydroxyl or carboxylic groups were applied as matrixes for polymer-dye supramolecular systems. They revealed glass transition temperatures (Tg) in the range of 170-260 °C, whereas supramolecular systems exhibited lower Tg (88-187 °C). The polymers were easily soluble in aprotic polar solvents and exhibited remarkable good film forming properties. Moreover, new chromophore 4-[4-(3-hydroxypropyloxy)phenylazo]pyridine was synthesized and characterized. The light induced SRGs formation and simultaneous formation of the polarization gratings were explored in prepared polymer-chromophore assembles films using a holographic grating recording technique. First time to the best of our knowledge SRGs were formed in hydrogen-bonded supramolecular systems based on polyimides. The highest SRG amplitude and thus the highest diffraction efficiency were obtained in poly(esterimide)s with the hydroxyl functional group. Additionally, the thermal stability of the photoinduced surface gratings and polarization gratings were tested revealing in the case of the SRGs partial stability and almost complete erasure of the polarization gratings.

  15. Blazed Gratings Recorded in Absorbent Photopolymers

    Directory of Open Access Journals (Sweden)

    Roberto Fernández

    2016-03-01

    Full Text Available Phase diffractive optical elements, which have many interesting applications, are usually fabricated using a photoresist. In this paper, they were made using a hybrid optic-digital system and a photopolymer as recording medium. We analyzed the characteristics of the input and recording light and then simulated the generation of blazed gratings with different spatial periods in different types of photopolymers using a diffusion model. Finally, we analyzed the output and diffraction efficiencies of the 0 and 1st order so as to compare the simulated values with those measured experimentally. We evaluated the effects of index matching in a standard PVA/AA photopolymer, and in a variation of Biophotopol, a more biocompatible photopolymer. Diffraction efficiencies near 70%, for a wavelength of 633 nm, were achieved for periods longer than 300 µm in this kind of materials.

  16. Fork gratings based on ferroelectric liquid crystals.

    Science.gov (United States)

    Ma, Y; Wei, B Y; Shi, L Y; Srivastava, A K; Chigrinov, V G; Kwok, H-S; Hu, W; Lu, Y Q

    2016-03-21

    In this article, we disclose a fork grating (FG) based on the photo-aligned ferroelectric liquid crystal (FLC). The Digital Micro-mirror Device based system is used as a dynamic photomask to generated different holograms. Because of controlled anchoring energy, the photo alignment process offers optimal conditions for the multi-domain FLC alignment. Two different electro-optical modes namely DIFF/TRANS and DIFF/OFF switchable modes have been proposed where the diffraction can be switched either to no diffraction or to a completely black state, respectively. The FLC FG shows high diffraction efficiency and fast response time of 50µs that is relatively faster than existing technologies. Thus, the FLC FG may pave a good foundation toward optical vertices generation and manipulation that could find applications in a variety of devices.

  17. Low efficiency gratings for 3rd harmonic diagnostics applications

    International Nuclear Information System (INIS)

    Britten, J.A.; Boyd, R.D.; Perry, M.D.; Shore, B.W.; Thomas, I.M.

    1995-01-01

    The baseline design of the National Ignition Facility (NIF) calls for sampling gratings to provide third-harmonic energy diagnostics in the highly constrained area of the target chamber. These 40 x 4O cm transmission gratings are to diffract at (order +1) nominally 0.3% of the incident 351 run light at a small angle on to a focusing mirror and into a calorimeter. The design calls for a plane grating of 500 lines/mm, and approximately 30 run deep, etched into a fused silica focusing lens and subsequently overcoated with a solgel anti reflective coating. Gratings of similar aperture and feature size have been produced for other applications by ion etching processes, but, in an effort to reduce substantially the cost of such optics, we are studying the feasibility of making these gratings by wet chemical etching techniques. Experimentation with high-quality fused silica substrates on 5 and 15 cm. scale has led to a wet etching process which can meet the design goals and which offers no significant scaleup barriers to full sized optics. The grating is produced by holographic exposure and a series of processing steps using only a photoresist mask and a final hydrofluoric acid etch. Gratings on 15 cm diameter test substrates exhibit absolute diffraction efficiencies from 0.2--0.4% with a standard deviation of about 15% of the mean over the full aperture. The efficiency variation is due to variation in linewidth caused by spatial nonuniformities in exposure energy. Uniformity improvements can be realized by using a smaller, more uniform portion of the exposure beam and exposing for longer times. The laser damage threshold for these gratings has been measured at LLNL and found to be identical to that of the fused silica substrate

  18. Interacting binaries

    CERN Document Server

    Shore, S N; van den Heuvel, EPJ

    1994-01-01

    This volume contains lecture notes presented at the 22nd Advanced Course of the Swiss Society for Astrophysics and Astronomy. The contributors deal with symbiotic stars, cataclysmic variables, massive binaries and X-ray binaries, in an attempt to provide a better understanding of stellar evolution.

  19. An update on X-ray reflection gratings developed for future missions

    Science.gov (United States)

    Miles, Drew

    2018-01-01

    X-ray reflection gratings are a key technology being studied for future X-ray spectroscopy missions, including the Lynx X-ray mission under consideration for the 2020 Decadal Survey. We present an update on the status of X-ray reflection gratings being developed at Penn State University, including current fabrication techniques and mass-replication processes and the latest diffraction efficiency results and resolving power measurements. Individual off-plane X-ray reflection gratings have exceeded the current Lynx requirements for both effective area and resolving power. Finally, we discuss internal projects that will advance the technology readiness level of these gratings.

  20. Topology-optimized broadband surface relief transmission grating

    DEFF Research Database (Denmark)

    Andkjær, Jacob; Ryder, Christian P.; Nielsen, Peter C.

    2014-01-01

    We propose a design methodology for systematic design of surface relief transmission gratings with optimized diffraction efficiency. The methodology is based on a gradient-based topology optimization formulation along with 2D frequency domain finite element simulations for TE and TM polarized plane...

  1. Optimization for sinusoidal profiles in surface relief gratings ...

    Indian Academy of Sciences (India)

    2014-02-07

    Feb 7, 2014 ... ometric pattern in photosensitive materials such as photoresists and many other types of photopolymers that are capable of generating surface relief structures. Indigenous devel- opment of such diffraction gratings has been taken up in our department for laser and spectroscopic applications. The purpose ...

  2. Switchable Bragg gratings

    DEFF Research Database (Denmark)

    Marckmann, Carl Johan

    2003-01-01

    Research Center (MIC) at the Technical University of Denmark. The Bragg gratings were fabricated at COM using UV irradiation of the planar waveguides using the phase mask method. The induction of a frozen-in DC electric field into the samples was performed by thermal poling of the Bragg gratings...... layers, it becam possible to investigate the symmetry properties of the third-order nonlinearities. Contrary to the expectations for an amorphous material, the measurements indicated an almost polarization independent third-order nonlinearity - the most probable explanation being electrostriction......The subject of this ph.d. thesis was the development of an electrically switchable Bragg grating made in an optical waveguide using thermal poling to be applied within optical telecommunication systems. The planar waveguides used in this thesis were fabricated at the Micro- and Nanotechnology...

  3. The effect of aberrated recording beams on reflecting Bragg gratings

    Science.gov (United States)

    SeGall, Marc; Ott, Daniel; Divliansky, Ivan; Glebov, Leonid B.

    2013-03-01

    The effect of aberrations present in the recording beams of a holographic setup is discussed regarding the period and spectral response of a reflecting volume Bragg grating. Imperfect recording beams result in spatially varying resonant wavelengths and the side lobes of the spectrum are washed out. Asymmetrical spectra, spectral broadening, and a reduction in peak diffraction efficiency may also be present, though these effects are less significant for gratings with wider spectral widths. Reflecting Bragg gratings (RBGs) are used as elements in a variety of applications including spectral beam combining1,2, mode locking3,4, longitudinal and transverse mode selection in lasers5,6, and sensing7,8. For applications requiring narrow spectral selectivity9, or large apertures10, these gratings must have a uniform period throughout the length of the recording medium, which may be on the order of millimeters. However, when using typical recording techniques such as two-beam interference for large aperture gratings and phase-mask recording of fiber gratings, aberrations from the optical elements in the system result in an imperfect grating structure11-13. In this paper we consider the effects of aberrations on large aperture gratings recorded in thick media using the two-beam interference technique. Previous works in analyzing the effects of aberrations have considered the effects of aberrations in a single recording plane where the beams perfectly overlap. Such an approach is valid for thin media (on the order of tens of microns), but for thick recording media (on the order of several millimeters) there will be a significant shift in the positions of the beams relative to each other as they traverse the recording medium. Therefore, the fringe pattern produced will not be constant throughout the grating if one or both beams have a non-uniform wavefront. Such non-uniform gratings may have a wider spectral width, a shifted resonant wavelength, or other problems. It is

  4. Transmission Grating and Optics Technology Development for the Arcus Explorer Mission

    Science.gov (United States)

    Heilmann, Ralf; Arcus Team

    2018-01-01

    Arcus is a high-resolution x-ray spectroscopy MIDEX mission selected for a Phase A concept study. It is designed to explore structure formation through measurements of hot baryon distributions, feedback from black holes, and the formation and evolution of stars, disks, and exoplanet atmospheres. The design provides unprecedented sensitivity in the 1.2-5 nm wavelength band with effective area above 450 sqcm and spectral resolution R > 2500. The Arcus technology is based on 12 m-focal length silicon pore optics (SPO) developed for the European Athena mission, and critical-angle transmission (CAT) x-ray diffraction gratings and x-ray CCDs developed at MIT. The modular design consists of four parallel channels, each channel holding an optics petal, followed by a grating petal. CAT gratings are lightweight, alignment insensitive, high-efficiency x-ray transmission gratings that blaze into high diffraction orders, leading to high spectral resolution. Each optics petal represents an azimuthal sub-aperture of a full Wolter optic. The sub-aperturing effect increases spectral resolving power further. Two CCD readout strips receive photons from each channel, including higher-energy photons in 0th order. Each optics petal holds 34 SPO modules. Each grating petal holds 34 grating windows, and each window holds 4-6 grating facets. A grating facet consists of a silicon grating membrane, bonded to a flexure frame that interfaces with the grating window. We report on a sequence of tests with increasing complexity that systematically increase the Technology Readiness Level (TRL) for the combination of CAT gratings and SPOs towards TLR 6. CAT gratings have been evaluated in x rays for diffraction efficiency (> 30% at 2.5 nm) and for resolving power (R> 10,000). A CAT grating/SPO combination was measured at R ~ 3100 at blaze angles smaller than design values, exceeding Arcus requirements. Efficiency and resolving power were not impacted by vibration and thermal testing of gratings. A

  5. Three types of immersion grating for next-generation infrared spectrometer

    Science.gov (United States)

    Sukegawa, Takashi; Okura, Yukinobu

    2017-02-01

    Since an immersion grating provides n (n: refractive index of its material) times higher spectral resolution compared to a conventional reflective grating of the same size, an immersion grating is a powerful optical device for the infrared high-resolution spectrometer. Recently a high-resolution spectrometer in the infrared wavelength range is increasing the importance increasingly for observations of relating with H2O, NHx, NOx and organic molecules. Higher spectral resolution allows us to detect weak lines without spectral line confusion. On the other hands, there is no practical immersion grating for high-resolution spectrometer except Si immersion grating by anisotropic etching. It was very difficult for a fragile IR crystal to manufacture a diffraction grating precisely by machining. Our original free-forming machine has accuracy of a few nano-meter in positioning and stability. We succeeded in fabricating immersion gratings with three kinds of materials. Three materials are CdZnTe, germanium and InP, each refractive index is about 2.7, 4.0 and 3.2 respectively. By combining these devices, a spectrometer with immersion grating is realizable in the wavelength range of 1.5-20um. Thereby, the realization of these immersion gratings has led to a dramatic improvement in the operability and performance of next generation high-performance spectrometer. In this paper, we report performance of our immersion gratings and other possibility.

  6. Analysis of higher order harmonics with holographic reflection gratings

    Science.gov (United States)

    Mas-Abellan, P.; Madrigal, R.; Fimia, A.

    2017-05-01

    Silver halide emulsions have been considered one of the most energetic sensitive materials for holographic applications. Nonlinear recording effects on holographic reflection gratings recorded on silver halide emulsions have been studied by different authors obtaining excellent experimental results. In this communication specifically we focused our investigation on the effects of refractive index modulation, trying to get high levels of overmodulation that will produce high order harmonics. We studied the influence of the overmodulation and its effects on the transmission spectra for a wide exposure range by use of 9 μm thickness films of ultrafine grain emulsion BB640, exposed to single collimated beams using a red He-Ne laser (wavelength 632.8 nm) with Denisyuk configuration obtaining a spatial frequency of 4990 l/mm recorded on the emulsion. The experimental results show that high overmodulation levels of refractive index produce second order harmonics with high diffraction efficiency (higher than 75%) and a narrow grating bandwidth (12.5 nm). Results also show that overmodulation produce diffraction spectra deformation of the second order harmonic, transforming the spectrum from sinusoidal to approximation of square shape due to very high overmodulation. Increasing the levels of overmodulation of refractive index, we have obtained higher order harmonics, obtaining third order harmonic with diffraction efficiency (up to 23%) and narrowing grating bandwidth (5 nm). This study is the first step to develop a new easy technique to obtain narrow spectral filters based on the use of high index modulation reflection gratings.

  7. Optical fiber Bragg gratings. Part II. Modeling of finite-length gratings and grating arrays.

    Science.gov (United States)

    Passaro, Vittorio M N; Diana, Roberto; Armenise, Mario N

    2002-09-01

    A model of both uniform finite-length optical fiber Bragg gratings and grating arrays is presented. The model is based on the Floquet-Bloch formalism and allows rigorous investigation of all the physical aspects in either single- or multiple-periodic structures realized on the core of a monomodal fiber. Analytical expressions of reflectivity and transmittivity for both single gratings and grating arrays are derived. The influence of the grating length and the index modulation amplitude on the reflected and transmitted optical power for both sinusoidal and rectangular profiles is evaluated. Good agreement between our method and the well-known coupled-mode theory (CMT) approach has been observed for both single gratings and grating arrays only in the case of weak index perturbation. Significant discrepancies exist there in cases of strong index contrast because of the increasing approximation of the CMT approach. The effects of intragrating phase shift are also shown and discussed.

  8. Miniaturized diffraction based interferometric distance measurement sensor

    Science.gov (United States)

    Kim, Byungki

    In this thesis, new metrology hardware is designed, fabricated, and tested to provide improvements over current MEMS metrology. The metrology system is a micromachined scanning interferometer (muSI) having a sub-nm resolution in a compact design. The proposed microinterferometer forms a phase sensitive diffraction grating with interferomeric sensitivity, while adding the capability of better lateral resolution by focusing the laser to a smaller spot size. A detailed diffraction model of the microinterferometer was developed to simulate the device performance and to suggest the location of photo detectors for integrated optoelectronics. A particular device is fabricated on a fused silica substrate using aluminum to form the deformable diffraction grating fingers and AZ P4620 photo resist (PR) for the microlens. The details of the fabrication processes are presented. The structure also enables optoelectronics to be integrated so that the interferometer with photo detectors can fit in an area that is 1 mm x 1 mm. The scanning results using a fixed grating muSI demonstrated that it could measure vibration profile as well as static vertical (less than a half wave length) and lateral dimension of MEMS. The muSI, which is integrated with photo diodes, demonstrated its operation by scanning a cMUT. The PID control has been tested and resulted in improvement in scanned images. The integrated muSI demonstrated that the deformable grating could be used to tune the measurement keep the interferometer in quadrature for highest sensitivity.

  9. Nonlinear Absorptions in Liquids Studied by Laser - Anharmonic Thermal Gratings.

    Science.gov (United States)

    Zhu, Xiao-Rong

    In an absorbing medium, nonlinear absorption at a crossed-beam interference pattern creates, through absorptive heating, a temperature modulation containing harmonics of the spatial frequency of the excitation interference pattern, and the temperature dependence of the refractive index then results in an anharmonic volume index grating. A probe beam incident at the Bragg angle for a given spatial harmonic grating will produce a single diffraction order. By measuring the excitation intensity dependence of diffraction efficiencies at several Bragg angles, one can distinguish between various mechanisms of nonlinear absorption. In this dissertation, nonlinear absorption by organic molecules in liquids, with a focus on the sequential two-step absorption, has been studied by a laser-induced anharmonic thermal grating techniques. The nonlinear absorption of all-trans- beta-carotene, a biologically important natural product, in liquids is first investigated, and the results indicate that nonlinear absorption of beta -carotene in hexane is caused by the excited-state absorption, and while the saturation observed in chloroform is due to formation of a long-lived photoisomer. The effect of photoisomerization on saturated absorption of the cyanine laser dye DODCI in alcohols is then examined. It is found that the weaker absorption by the photoisomer and reverse -photoisomerization have made saturation of optical absorption of DODCI difficult. A general numerical method is developed for the first time to treat rigorously the problem of diffraction from anharmonic Gaussian volume gratings. It shows that the previously developed quasi-plane wave approximation (QPWA) theory is valid only at the weak saturation limit for a saturation absorption model. Finally, anomalous dependence of diffraction intensities on the excitation intensity for two tricarbocyanine dyes is observed. A careful analysis shows that it is caused by diffraction from multiple thermal gratings with a 180^ circ

  10. Visualizing the propagation of volume magnetization in bulk ferromagnetic materials by neutron grating interferometry (invited)

    Czech Academy of Sciences Publication Activity Database

    Grünzweig, C.; David, C.; Bunk, O.; Kohlbrecher, J.; Lehmann, E.; Lai, Y.W.; Schäfer, R.; Roth, S.; Lejček, Pavel; Kopeček, Jaromír; Pfeiffer, F.

    2010-01-01

    Roč. 107, č. 9 (2010), 09D308/1-09D308/6 ISSN 0021-8979 Institutional research plan: CEZ:AV0Z10100520 Keywords : diffraction gratings * ferromagnetic materials * finite element analysis * magnetic domain walls * magnetisation * neutron diffraction * steel Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.064, year: 2010

  11. High efficiency multilayer blazed gratings for EUV and soft X-rays: Recent developments

    International Nuclear Information System (INIS)

    Voronov, Dmitriy; Ahn, Minseung; Anderson, Erik; Cambie, Rossana; Chang, Chih-Hao; Goray, Leonid; Gullikson, Eric; Heilmann, Ralf; Salmassi, Farhad; Schattenburg, Mark; Warwick, Tony; Yashchuk, Valeriy; Padmore, Howard

    2011-01-01

    Multilayer coated blazed gratings with high groove density are the best candidates for use in high resolution EUV and soft x-ray spectroscopy. Theoretical analysis shows that such a grating can be potentially optimized for high dispersion and spectral resolution in a desired high diffraction order without significant loss of diffraction efficiency. In order to realize this potential, the grating fabrication process should provide a perfect triangular groove profile and an extremely smooth surface of the blazed facets. Here we report on recent progress achieved at the Advanced Light Source (ALS) in fabrication of high quality multilayer coated blazed gratings. The blazed gratings were fabricated using scanning beam interference lithography followed by wet anisotropic etching of silicon. A 200 nm period grating coated with a Mo/Si multilayer composed with 30 bi-layers demonstrated an absolute efficiency of 37.6percent in the 3rd diffraction order at 13.6 nm wavelength. The groove profile of the grating was thoroughly characterized with atomic force microscopy before and after the multilayer deposition. The obtained metrology data were used for simulation of the grating efficiency with the vector electromagnetic PCGrate-6.1 code. The simulations showed that smoothing of the grating profile during the multilayer deposition is the main reason for efficiency losses compared to the theoretical maximum. Investigation of the grating with cross-sectional transmission electron microscopy revealed a complex evolution of the groove profile in the course of the multilayer deposition. Impact of the shadowing and smoothing processes on growth of the multilayer on the surface of the sawtooth substrate is discussed.

  12. Grating stimulated echo

    International Nuclear Information System (INIS)

    Dubetsky, B.; Berman, P.R.; Sleator, T.

    1992-01-01

    A theory of a grating simulated echo (GTE) is developed. The GSE involves the sequential excitation of atoms by two counterpropagating traveling waves, a standing wave, and a third traveling wave. It is shown that the echo signal is very sensitive to small changes in atomic velocity, much more sensitive than the normal stimulated echo. Use of the GSE as a collisional probe or accelerometer is discussed

  13. A general theory of interference fringes in x-ray phase grating imaging

    International Nuclear Information System (INIS)

    Yan, Aimin; Wu, Xizeng; Liu, Hong

    2015-01-01

    Purpose: The authors note that the concept of the Talbot self-image distance in x-ray phase grating interferometry is indeed not well defined for polychromatic x-rays, because both the grating phase shift and the fractional Talbot distances are all x-ray wavelength-dependent. For x-ray interferometry optimization, there is a need for a quantitative theory that is able to predict if a good intensity modulation is attainable at a given grating-to-detector distance. In this work, the authors set out to meet this need. Methods: In order to apply Fourier analysis directly to the intensity fringe patterns of two-dimensional and one-dimensional phase grating interferometers, the authors start their derivation from a general phase space theory of x-ray phase-contrast imaging. Unlike previous Fourier analyses, the authors evolved the Wigner distribution to obtain closed-form expressions of the Fourier coefficients of the intensity fringes for any grating-to-detector distance, even if it is not a fractional Talbot distance. Results: The developed theory determines the visibility of any diffraction order as a function of the grating-to-detector distance, the phase shift of the grating, and the x-ray spectrum. The authors demonstrate that the visibilities of diffraction orders can serve as the indicators of the underlying interference intensity modulation. Applying the theory to the conventional and inverse geometry configurations of single-grating interferometers, the authors demonstrated that the proposed theory provides a quantitative tool for the grating interferometer optimization with or without the Talbot-distance constraints. Conclusions: In this work, the authors developed a novel theory of the interference intensity fringes in phase grating x-ray interferometry. This theory provides a quantitative tool in design optimization of phase grating x-ray interferometers

  14. A general theory of interference fringes in x-ray phase grating imaging.

    Science.gov (United States)

    Yan, Aimin; Wu, Xizeng; Liu, Hong

    2015-06-01

    The authors note that the concept of the Talbot self-image distance in x-ray phase grating interferometry is indeed not well defined for polychromatic x-rays, because both the grating phase shift and the fractional Talbot distances are all x-ray wavelength-dependent. For x-ray interferometry optimization, there is a need for a quantitative theory that is able to predict if a good intensity modulation is attainable at a given grating-to-detector distance. In this work, the authors set out to meet this need. In order to apply Fourier analysis directly to the intensity fringe patterns of two-dimensional and one-dimensional phase grating interferometers, the authors start their derivation from a general phase space theory of x-ray phase-contrast imaging. Unlike previous Fourier analyses, the authors evolved the Wigner distribution to obtain closed-form expressions of the Fourier coefficients of the intensity fringes for any grating-to-detector distance, even if it is not a fractional Talbot distance. The developed theory determines the visibility of any diffraction order as a function of the grating-to-detector distance, the phase shift of the grating, and the x-ray spectrum. The authors demonstrate that the visibilities of diffraction orders can serve as the indicators of the underlying interference intensity modulation. Applying the theory to the conventional and inverse geometry configurations of single-grating interferometers, the authors demonstrated that the proposed theory provides a quantitative tool for the grating interferometer optimization with or without the Talbot-distance constraints. In this work, the authors developed a novel theory of the interference intensity fringes in phase grating x-ray interferometry. This theory provides a quantitative tool in design optimization of phase grating x-ray interferometers.

  15. A general theory of interference fringes in x-ray phase grating imaging

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Aimin; Wu, Xizeng, E-mail: xwu@uabmc.edu, E-mail: liu@ou.edu [Department of Radiology, University of Alabama at Birmingham, Birmingham, Alabama 35249 (United States); Liu, Hong, E-mail: xwu@uabmc.edu, E-mail: liu@ou.edu [Center for Bioengineering and School of Electrical and Computer Engineering, University of Oklahoma, Norman, Oklahoma 73019 (United States)

    2015-06-15

    Purpose: The authors note that the concept of the Talbot self-image distance in x-ray phase grating interferometry is indeed not well defined for polychromatic x-rays, because both the grating phase shift and the fractional Talbot distances are all x-ray wavelength-dependent. For x-ray interferometry optimization, there is a need for a quantitative theory that is able to predict if a good intensity modulation is attainable at a given grating-to-detector distance. In this work, the authors set out to meet this need. Methods: In order to apply Fourier analysis directly to the intensity fringe patterns of two-dimensional and one-dimensional phase grating interferometers, the authors start their derivation from a general phase space theory of x-ray phase-contrast imaging. Unlike previous Fourier analyses, the authors evolved the Wigner distribution to obtain closed-form expressions of the Fourier coefficients of the intensity fringes for any grating-to-detector distance, even if it is not a fractional Talbot distance. Results: The developed theory determines the visibility of any diffraction order as a function of the grating-to-detector distance, the phase shift of the grating, and the x-ray spectrum. The authors demonstrate that the visibilities of diffraction orders can serve as the indicators of the underlying interference intensity modulation. Applying the theory to the conventional and inverse geometry configurations of single-grating interferometers, the authors demonstrated that the proposed theory provides a quantitative tool for the grating interferometer optimization with or without the Talbot-distance constraints. Conclusions: In this work, the authors developed a novel theory of the interference intensity fringes in phase grating x-ray interferometry. This theory provides a quantitative tool in design optimization of phase grating x-ray interferometers.

  16. Critical-angle x-ray transmission grating spectrometer with extended bandpass and resolving power > 10,000

    Science.gov (United States)

    Heilmann, Ralf K.; Bruccoleri, Alexander R.; Kolodziejczak, Jeffery; Gaskin, Jessica A.; O'Dell, Stephen L.; Bhatia, Ritwik; Schattenburg, Mark L.

    2016-07-01

    A number of high priority subjects in astrophysics can be addressed by a state-of-the-art soft x-ray grating spectrometer, such as the role of Active Galactic Nuclei in galaxy and star formation, characterization of the Warm-Hot Intergalactic Medium and the missing baryon problem, characterization of halos around the Milky Way and nearby galaxies, as well as stellar coronae and surrounding winds and disks. An Explorer-scale, largearea (> 1,000 cm2), high resolving power (R =λ/Δλ > 3,000) soft x-ray grating spectrometer is highly feasible based on Critical-Angle Transmission (CAT) grating technology, even for telescopes with angular resolution of 5-10 arcsec. Still, significantly higher performance can be provided by a CAT grating spectrometer on an X-ray- Surveyor-type mission. CAT gratings combine the advantages of blazed reflection gratings (high efficiency, use of higher diffraction orders) with those of conventional transmission gratings (lowmass, relaxed alignment tolerances and temperature requirements, transparent at higher energies) with minimalmission resource requirements. They are high-efficiency blazed transmission gratings that consist of freestanding, ultra-high aspect-ratio grating bars fabricated from silicon-on-insulator (SOI) wafers using advanced anisotropic dry and wet etch techniques. Blazing is achieved through grazing-incidence reflection off the smooth grating bar sidewalls. The reflection properties of silicon are well matched to the soft x-ray band, and existing silicon CAT gratings can exceed 30% absolute diffraction efficiency, with clear paths for further improvement. Nevertheless, CAT gratings with sidewalls made of higher atomic number elements allow extension of the CAT grating principle to higher energies and larger dispersion angles, thus enabling higher resolving power at shorter wavelengths. We show x-ray data from CAT gratings coated with a thin layer of platinum using atomic layer deposition, and demonstrate efficient

  17. Microfabricated silicon gratings as neutron-optical components

    Science.gov (United States)

    Trinker, M.; Jericha, E.; Loidl, R.; Rauch, H.

    2008-02-01

    Microfabricated silicon gratings provide unique test procedures for instruments in neutron scattering and the interpretation of experimental data. Ultra-Small Angle Neutron Scattering (USANS) is currently becoming an effective technique for the analysis of structures in the micrometer range. A series of one-dimensional silicon gratings was fabricated using a highly anisotropic ion etching technique (RIE) and measured at the USANS instrument S18 at ILL, Grenoble. The scattering patterns show up to 17 orders of diffraction, grating parameters derived from these data are in good agreement with the nominal values. Scattering length density correlation functions calculated from the USANS data are compared to Spin Echo SANS (SESANS) correlation functions measured at the Delft University of Technology, demonstrating the complementarity of the two scattering methods.

  18. Microfabricated silicon gratings as neutron-optical components

    Energy Technology Data Exchange (ETDEWEB)

    Trinker, M. [Atominstitut, Vienna University of Technology, A-1020 Vienna (Austria)], E-mail: mtrinker@ati.ac.at; Jericha, E. [Atominstitut, Vienna University of Technology, A-1020 Vienna (Austria); Loidl, R. [Atominstitut, Vienna University of Technology, A-1020 Vienna (Austria); Institute Laue-Langevin, F-38042 Grenoble (France); Rauch, H. [Atominstitut, Vienna University of Technology, A-1020 Vienna (Austria)

    2008-02-11

    Microfabricated silicon gratings provide unique test procedures for instruments in neutron scattering and the interpretation of experimental data. Ultra-Small Angle Neutron Scattering (USANS) is currently becoming an effective technique for the analysis of structures in the micrometer range. A series of one-dimensional silicon gratings was fabricated using a highly anisotropic ion etching technique (RIE) and measured at the USANS instrument S18 at ILL, Grenoble. The scattering patterns show up to 17 orders of diffraction, grating parameters derived from these data are in good agreement with the nominal values. Scattering length density correlation functions calculated from the USANS data are compared to Spin Echo SANS (SESANS) correlation functions measured at the Delft University of Technology, demonstrating the complementarity of the two scattering methods.

  19. Microfabricated silicon gratings as neutron-optical components

    International Nuclear Information System (INIS)

    Trinker, M.; Jericha, E.; Loidl, R.; Rauch, H.

    2008-01-01

    Microfabricated silicon gratings provide unique test procedures for instruments in neutron scattering and the interpretation of experimental data. Ultra-Small Angle Neutron Scattering (USANS) is currently becoming an effective technique for the analysis of structures in the micrometer range. A series of one-dimensional silicon gratings was fabricated using a highly anisotropic ion etching technique (RIE) and measured at the USANS instrument S18 at ILL, Grenoble. The scattering patterns show up to 17 orders of diffraction, grating parameters derived from these data are in good agreement with the nominal values. Scattering length density correlation functions calculated from the USANS data are compared to Spin Echo SANS (SESANS) correlation functions measured at the Delft University of Technology, demonstrating the complementarity of the two scattering methods

  20. Wavefront analysis of high-efficiency, large-scale, thin transmission gratings.

    Science.gov (United States)

    Zhou, Chun; Seki, Takashi; Kitamura, Tsuyoshi; Kuramoto, Yoshiyuki; Sukegawa, Takashi; Ishii, Nobuhisa; Kanai, Teruto; Itatani, Jiro; Kobayashi, Yohei; Watanabe, Shuntaro

    2014-03-10

    Large-scale (180 × 60 × 1 mm(3)) transmission gratings with groove densities of 1250 and 1740 lines/mm have been developed, resulting in diffraction efficiencies above 95%. The throughput of a folded pulse compressor with two large-scale transmission gratings was approximately 80% in a 20-fs Ti:sapphire chirped-pulse amplification (CPA) laser. The parabolic bending of the transmission grating due to anti-reflection (AR) coating was minimized to 2.9 λ at 633 nm by improving the evaporation process. By a simple analysis, we explain why this level of bending does not induce a wavefront distortion through the transmission grating near the Littrow condition while the wavefront from a reflection grating is distorted to nearly twice the bending of the grating. The calculation based on the measured bending shows that both the group delay difference relative to the ideally flat grating from 750 to 850 nm and the spatial pulse front distortion over a 60-mm-diameter input beam are negligible, even when the dispersive beam covers ~140 mm on the grating. The spatial pulse front distortion measured after the compressor was less than the measurement limit (1.5 fs) for a 20-mm-diameter beam, where the beam size in the dispersive direction on the grating was 85 mm.

  1. Diffraction dissociation

    International Nuclear Information System (INIS)

    Abarbanel, H.

    1972-01-01

    An attempt is made to analyse the present theoretical situation in the field of diffraction scattering. Two not yet fully answered questions related with a typical diffraction process AB→CD, namely: what is the structure of the transition matrix elements, and what is the structure of the exchange mechanism responsible for the scattering, are formulated and various proposals for answers are reviewed. Interesting general statement that the products (-1)sup(J)P, where J and P are respectively spin and parity, is conserved at each vertex has been discussed. The exchange mechanism in diffractive scattering has been considered using the language of the complex J-plane as the most appropriate. The known facts about the exchange mechanism are recalled and several routs to way out are proposed. The idea to consider the moving pole and associated branch points as like a particle and the associated two and many particle unitarity cuts is described in more details. (S.B.)

  2. Neutron diffraction

    International Nuclear Information System (INIS)

    Heger, G.

    1996-01-01

    X-ray diffraction using conventional laboratory equipment and/or synchrotron installations is the most important method for structure analyses. The purpose of this paper is to discuss special cases, for which, in addition to this indispensable part, neutrons are required to solve structural problems. Even though the huge intensity of modern synchrotron sources allows in principle the study of magnetic X-ray scattering the investigation of magnetic structures is still one of the most important applications of neutron diffraction. (author) 15 figs., 1 tab., 10 refs

  3. Neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Heger, G. [Rheinisch-Westfaelische Technische Hochschule Aachen, Inst. fuer Kristallographie, Aachen (Germany)

    1996-12-31

    X-ray diffraction using conventional laboratory equipment and/or synchrotron installations is the most important method for structure analyses. The purpose of this paper is to discuss special cases, for which, in addition to this indispensable part, neutrons are required to solve structural problems. Even though the huge intensity of modern synchrotron sources allows in principle the study of magnetic X-ray scattering the investigation of magnetic structures is still one of the most important applications of neutron diffraction. (author) 15 figs., 1 tab., 10 refs.

  4. Compact diffraction grating laser wavemeter for cold atom experiments

    Science.gov (United States)

    Wei, Chun-hua; Yan, Shu-hua; Zhang, Tian

    2017-09-01

    We present an innovative and practical scheme of building a miniaturized wavemeter, with the advantages of low cost, high reliability and simple structure. Through a calibration test by a 780 nm external cavity diode laser (ECDL), the results show that our system gets a wavelength resolution of better than 1 pm, measurement accuracy of better than 2 pm (corresponding to a frequency of 1 GHz), and a measurement range of 8.5 nm. Finally, the multi-mode comparison test between our system and a commercial spectrum analyzer further indicates the high-precision, miniaturization and low cost of the proposed system, which shows that it is particularly suitable for ECDL and atom cooling and trapping experiments. The system design, experimental results and conclusions are of definite significance as a fine reference for other ranges of wavelength.

  5. Volume gratings and welding of glass/plastic by femtosecond laser direct writing

    Science.gov (United States)

    Watanabe, Wataru

    2018-01-01

    Femtosecond laser direct writing is used to fabricate diffractive optical elements in three dimensions and to weld glass and/or plastic. In this paper, we review volume gratings in plastics and welding of glass/plastic by femtosecond laser direct writing. Volume gratings were embedded inside polymethyl methacrylate (PMMA) by femtosecond laser pulses. The diffraction efficiency of the gratings increased after fabrication and reached the maximum. After an initial slow decrease within first several days after the fabrication, the efficiency increased again. This phenomena was called regeneration of the grating. We also demonstrate welding of PMMA by dendrite pattern using femtosecond laser pulses. Laser pulses are focused at the interface of two PMMA substrates with an air gap and melted materials in laser-irradiated region spread within a gap of the substrates and dendrite morphology of melted PMMA was observed outside the laser irradiated area. Finally, we show welding of glass/plastic and metal.

  6. Physical mechanism of beam splitting based on reflective embedded double-layer grating

    Science.gov (United States)

    Wang, Bo; Li, Hongtao; Shu, Wenhao; Li, Wenhua; Chen, Li; Lei, Liang; Zhou, Jinyun

    2016-12-01

    It is not easy to achieve high performance for conventional beam splitters, such as high efficiency, good uniformity, polarization-independence, and wide bandwidth. A reflective embedded double-layer grating is described for beam splitting. With optimized grating profiles, the novel beam splitter can diffract both TE and TM polarizations into two orders with high performance. For the easy production, the fabrication tolerance is investigated and given. Most importantly, efficiencies more than 45% can be split into two orders within the wide bandwidth of 1412-1647 nm for TE polarization. The beam splitter based on multilayer coatings is sensitive to the incident angle and wavelength. And the bandwidth needs to be improved for the beam splitter based on simple grating. The design is of benefit for the performance improvement of the beam splitter by new grating configuration compared with the conventional simple grating.

  7. Neutron diffraction

    International Nuclear Information System (INIS)

    Bacon, G.E.

    1983-01-01

    The paper reviews neutron diffraction work from the early studies to the present-day development of the subject. Direct structural investigations were described, including chemical applications associated with single crystal techniques, and magnetic applications identified with powder techniques. The properties of the neutron beams are discussed, as well as the use of polarised beams. (UK)

  8. Calibration of Modulation Transfer Function of Surface Profilometers with 1D and 2D Binary Pseudo-random Array Standards

    International Nuclear Information System (INIS)

    Yashchuk, Valeriy V.; McKinney, Wayne R.; Takacs, Peter Z.

    2008-01-01

    We suggest and describe the use of a binary pseudo-random grating as a standard test surface for calibration of the modulation transfer function of microscopes. Results from calibration of a MicromapTM-570 interferometric microscope are presented.

  9. An ultrafast nanotip electron gun triggered by grating-coupled surface plasmons

    Energy Technology Data Exchange (ETDEWEB)

    Schröder, Benjamin; Sivis, Murat; Bormann, Reiner; Schäfer, Sascha; Ropers, Claus, E-mail: cropers@gwdg.de [4th Physical Institute - Solids and Nanostructures, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen (Germany)

    2015-12-07

    We demonstrate multiphoton photoelectron emission from gold nanotips induced by nanofocusing surface plasmons, resonantly excited on the tip shaft by a grating coupler. The tip is integrated into an electron gun assembly, which facilitates control over the spatial emission sites and allows us to disentangle direct grating emission from plasmon-triggered apex emission. The nanoscale source size of this electron gun concept enables highly coherent electron pulses with applications in ultrafast electron imaging and diffraction.

  10. High performance Si immersion gratings patterned with electron beam lithography

    Science.gov (United States)

    Gully-Santiago, Michael A.; Jaffe, Daniel T.; Brooks, Cynthia B.; Wilson, Daniel W.; Muller, Richard E.

    2014-07-01

    Infrared spectrographs employing silicon immersion gratings can be significantly more compact than spectro- graphs using front-surface gratings. The Si gratings can also offer continuous wavelength coverage at high spectral resolution. The grooves in Si gratings are made with semiconductor lithography techniques, to date almost entirely using contact mask photolithography. Planned near-infrared astronomical spectrographs require either finer groove pitches or higher positional accuracy than standard UV contact mask photolithography can reach. A collaboration between the University of Texas at Austin Silicon Diffractive Optics Group and the Jet Propulsion Laboratory Microdevices Laboratory has experimented with direct writing silicon immersion grating grooves with electron beam lithography. The patterning process involves depositing positive e-beam resist on 1 to 30 mm thick, 100 mm diameter monolithic crystalline silicon substrates. We then use the facility JEOL 9300FS e-beam writer at JPL to produce the linear pattern that defines the gratings. There are three key challenges to produce high-performance e-beam written silicon immersion gratings. (1) E- beam field and subfield stitching boundaries cause periodic cross-hatch structures along the grating grooves. The structures manifest themselves as spectral and spatial dimension ghosts in the diffraction limited point spread function (PSF) of the diffraction grating. In this paper, we show that the effects of e-beam field boundaries must be mitigated. We have significantly reduced ghost power with only minor increases in write time by using four or more field sizes of less than 500 μm. (2) The finite e-beam stage drift and run-out error cause large-scale structure in the wavefront error. We deal with this problem by applying a mark detection loop to check for and correct out minuscule stage drifts. We measure the level and direction of stage drift and show that mark detection reduces peak-to-valley wavefront error

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

    Science.gov (United States)

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

    2015-09-01

    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 = λ/Δλ> 3000) soft x-ray grating spectrometer (XGS) that covers the lines of C, N, O, Ne and Fe ions is the ideal tool to address a number of high-priority science 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. While no grating missions or instruments are currently approved, an XGS aboard a potential future X-ray Surveyor could easily surpass the above performance metrics. To improve the chances for future soft x-ray grating spectroscopy missions or instruments, grating technology has to progress and advance to higher Technology Readiness Levels (TRLs). To that end 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, high transparency 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. At present we have fabricated large-area freestanding CAT gratings with narrow integrated support structures from silicon-on- insulator wafers using advanced lithography and a combination of deep reactive-ion and wet etching. Our latest x-ray test results show record high absolute diffraction efficiencies in blazed orders in excess of 30% with room for improvement.

  12. Input-output relations for a three-port grating coupled Fabry-Perot cavity

    OpenAIRE

    Bunkowski, Alexander; Burmeister, Oliver; Danzmann, Karsten; Schnabel, Roman

    2005-01-01

    We analyze an optical three-port reflection grating by means of a scattering matrix formalism. Amplitude and phase relations among the three ports, i.e., the three orders of diffraction, are derived. Such a grating can be used as an all-reflective, low-loss coupler to Fabry-Perot cavities. We derive the input-output relations of a three-port grating coupled cavity and find distinct properties that are not present in two-port coupled cavities. The cavity relations further reveal that the three...

  13. Method to fabricate orthogonal crossed gratings by an interference fringe based alignment technique

    Science.gov (United States)

    Zhou, Hengyan; Zeng, Lijiang

    2016-10-01

    In order to fabricate orthogonal crossed gratings, we propose an interference fringe based alignment technique to adjust the angle between the two Lloyd's mirrors to be 90° in the dual Lloyd's mirror interferometer. An exposed crossed grating is put back to the exposure system and rotated about 90° around its normal direction. By observing the fringe spacing of the interference fringes generated by the diffracted beams of different orders, we can adjust the angle between the two Lloyd's mirrors to be 90°. Simulation results indicate an orthogonality error smaller than 4″ can be obtained by this method. We fabricated a crossed grating with 0.30″ orthogonality error.

  14. Grating light reflection spectroelectrochemistry for detection of trace amounts of aromatic hydrocarbons in water

    Energy Technology Data Exchange (ETDEWEB)

    KELLY,MICHAEL J.; SWEATT,WILLIAM C.; KEMME,SHANALYN A.; KASUNIC,K.J.; BLAIR,DIANNA S.; ZAIDI,S.H.; MCNEIL,J.R.; BURGESS,L.W.; BRODSKY,A.M.; SMITH,S.A.

    2000-04-01

    Grating light reflection spectroscopy (GLRS) is an emerging technique for spectroscopic analysis and sensing. A transmission diffraction grating is placed in contact with the sample to be analyzed, and an incident light beam is directed onto the grating. At certain angles of incidence, some of the diffracted orders are transformed from traveling waves to evanescent waves. This occurs at a specific wavelength that is a function of the grating period and the complex index of refraction of the sample. The intensities of diffracted orders are also dependent on the sample's complex index of refraction. The authors describe the use of GLRS, in combination with electrochemical modulation of the grating, for the detection of trace amounts of aromatic hydrocarbons. The diffraction grating consisted of chromium lines on a fused silica substrate. The depth of the grating lines was 1 {micro}m, the grating period was 1 {micro}m, and the duty cycle was 50%. Since chromium was not suitable for electrochemical modulation of the analyte concentration, a 200 nm gold layer was deposited over the entire grating. This gold layer slightly degraded the transmission of the grating, but provided satisfactory optical transparency for the spectroelectrochemical experiments. The grating was configured as the working electrode in an electrochemical cell containing water plus trace amounts of the aromatic hydrocarbon analytes. The grating was then electrochemically modulated via cyclic voltammetry waveforms, and the normalized intensity of the zero order reflection was simultaneously measured. The authors discuss the lower limits of detection (LLD) for two analytes, 7-dimethylamino-1,2-benzophenoxazine (Meldola's Blue dye) and 2,4,6-trinitrotoluene (TNT), probed with an incident HeNe laser beam ({lambda} = 543.5 nm) at an incident angle of 52.5{degree}. The LLD for 7-dimethylamino-1,2-benzophenoxazine is approximately 50 parts per billion (ppb), while the LLD for TNT is approximately

  15. HOLOGRAPHIC GRATING RECORDING IN “LYOTROPIC LIQUID CRYSTAL – VIOLOGEN” SYSTEM

    Directory of Open Access Journals (Sweden)

    Hanna Bordyuh

    2013-12-01

    Full Text Available This work presents the results of nonlinear optical experiment run on the samples of lyotropic liquid crystal (LLC with viologen admixtures. During the experiment we obtained dynamic grating recording on bilayered LLC-viologen samples and determined main characteristics of recoded gratings. It was found out that the recording takes place in a thin near-cathode coloured viologen layer. The analysis of kinetics of thermal gratings erasing showed that contribution of a thermal nonlinearity into general diffraction efficiency is negligible small. The last fact is connected with a separation of LLC-viologen samples under the action of an electric field and heat sink into the liquid crystal layer

  16. Selectivity analysis of an incoherent grating imaged in a photorefractive crystal

    Science.gov (United States)

    Tebaldi, Myrian; Forte, Gustavo; Bolognini, Nestor; Lasprilla A., Maria del Carmen

    2018-04-01

    In this work, the diffraction efficiency of a volume phase grating incoherently stored in a photorefractive BSO crystal is theoretically and experimentally analyzed. The results confirm the theoretical proposal based on the coupled wave theory adopting a new grating depth parameter associated to the write-in incoherent optical system. The selectivity behavior is governed by the exit pupil diameter of the imaging recording system that controls the depth of the tridimensional image distribution along the propagation direction. Two incoherent gratings are multiplexed in a single crystal and reconstructed without cross-talk.

  17. Mass production of volume phase holographic gratings for the VIRUS spectrograph array

    Science.gov (United States)

    Chonis, Taylor S.; Frantz, Amy; Hill, Gary J.; Clemens, J. Christopher; Lee, Hanshin; Tuttle, Sarah E.; Adams, Joshua J.; Marshall, J. L.; DePoy, D. L.; Prochaska, Travis

    2014-07-01

    The Visible Integral-field Replicable Unit Spectrograph (VIRUS) is a baseline array of 150 copies of a simple, fiber-fed integral field spectrograph that will be deployed on the Hobby-Eberly Telescope (HET). VIRUS is the first optical astronomical instrument to be replicated on an industrial scale, and represents a relatively inexpensive solution for carrying out large-area spectroscopic surveys, such as the HET Dark Energy Experiment (HETDEX). Each spectrograph contains a volume phase holographic (VPH) grating with a 138 mm diameter clear aperture as its dispersing element. The instrument utilizes the grating in first-order for 350 VPH gratings has been mass produced for VIRUS. Here, we present the design of the VIRUS VPH gratings and a discussion of their mass production. We additionally present the design and functionality of a custom apparatus that has been used to rapidly test the first-order diffraction efficiency of the gratings for various discrete wavelengths within the VIRUS spectral range. This device has been used to perform both in-situ tests to monitor the effects of adjustments to the production prescription as well as to carry out the final acceptance tests of the gratings' diffraction efficiency. Finally, we present the as-built performance results for the entire suite of VPH gratings.

  18. Powder Diffraction

    Science.gov (United States)

    Hart, Michael

    The importance of x-ray powder diffraction as an analytical tool for phase identification of materials was first pointed out by Debye and Scherrer1,2 in Germany and, quite independently, by Hull3,4 in the United States of America. Three distinct periods of evolution lead to ubiquitous application in many fields of science and technology. In the, first period, until the- mid-1940's. applications were and developed covering broad categories of materials including inorganic materials, minerals, cerarffics, metals, alloys, organic materials and polymers. During this formative period, the concept of quantitative phase analysis was demonstrated5. In the second period there followed the blossoming of technology and commercial instruments became widely used. The history is well summarized by Parrish6 and by Langford and Loudr7. By 1980 there were probably 10000 powder diffractometers in routine use, making it the most widely used of all x-ray crystallographic instruments. In the third, present, period data bases became firmly established and sophisticated pattern fitting and recognition software made many aspects of powder diffraction analysis routine. High resolution, tunable powder diffractometers were developed at sources of synchrotron radiation8-10. The tunability of the spectrum made it possible to exploit all the subtleties of x-ray spectroscopy in diffraction experiments11.

  19. Neutron diffraction

    International Nuclear Information System (INIS)

    Howard, C.J.; Kennedy, S.J.

    1994-01-01

    A brief account is given of neutron diffraction techniques. Similarities and differences compared with the more familiar X-ray counterparts are discussed. In certain applications, neutron diffraction can be used to obtain information about materials which would be difficult or even impossible to obtain using other techniques. One spectacular success has been the elucidation, from neutron powder diffraction, of the crystal structures of high critical temperature oxide superconductors. There have been substantial contributions in other fields, and these are illustrated by Australian work. The ability of the neutron to penetrate deeply into most materials has been invoked for in-depth determination of stresses in composites and of phase composition in zirconia ceramics. The unique properties of the neutron have been successfully exploited in studies of metal hydrides, to determine where hydrogen is located, and in magnetic structure determination. There is much interest in studying materials under different conditions of temperature and pressure, and kinetic studies under such conditions are now becoming possible. The article includes information on the principles, the instrumentation with particular reference to the instruments installed around the HIFAR reactor at Lucas Heights, and methods for the interpretation of data. 59 refs., 3 tabs., 16 figs

  20. Powder diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Hart, M.

    1995-12-31

    the importance of x-ray powder diffraction as an analytical tool for phase identification of materials was first pointed out by Debye and Scherrer in Germany and, quite independently, by Hull in the US. Three distinct periods of evolution lead to ubiquitous application in many fields of science and technology. In the first period, until the mid-1940`s, applications were and developed covering broad categories of materials including inorganic materials, minerals, ceramics, metals, alloys, organic materials and polymers. During this formative period, the concept of quantitative phase analysis was demonstrated. In the second period there followed the blossoming of technology and commercial instruments became widely used. The history is well summarized by Parrish and by Langford and Loueer. By 1980 there were probably 10,000 powder diffractometers in routine use, making it the most widely used of all x-ray crystallographic instruments. In the third, present, period data bases became firmly established and sophisticated pattern fitting and recognition software made many aspects of powder diffraction analysis routine. High resolution, tunable powder diffractometers were developed at sources of synchrotron radiation. The tunability of the spectrum made it possible to exploit all the subtleties of x-ray spectroscopy in diffraction experiments.

  1. Powder diffraction

    International Nuclear Information System (INIS)

    Hart, M.

    1995-01-01

    The importance of x-ray powder diffraction as an analytical tool for phase identification of materials was first pointed out by Debye and Scherrer in Germany and, quite independently, by Hull in the US. Three distinct periods of evolution lead to ubiquitous application in many fields of science and technology. In the first period, until the mid-1940's, applications were and developed covering broad categories of materials including inorganic materials, minerals, ceramics, metals, alloys, organic materials and polymers. During this formative period, the concept of quantitative phase analysis was demonstrated. In the second period there followed the blossoming of technology and commercial instruments became widely used. The history is well summarized by Parrish and by Langford and Loueer. By 1980 there were probably 10,000 powder diffractometers in routine use, making it the most widely used of all x-ray crystallographic instruments. In the third, present, period data bases became firmly established and sophisticated pattern fitting and recognition software made many aspects of powder diffraction analysis routine. High resolution, tunable powder diffractometers were developed at sources of synchrotron radiation. The tunability of the spectrum made it possible to exploit all the subtleties of x-ray spectroscopy in diffraction experiments

  2. Multi-order nonlinear diffraction in second harmonic generation

    DEFF Research Database (Denmark)

    Saltiel, S. M.; Neshev, D.; Krolikowski, Wieslaw

    We analyze the emission patterns in the process of second harmonic (SH) generation in χ(2) nonlinear gratings and identify for the first time, to the best of our knowledge, the evidence of Raman-Nath type nonlinear diffraction in frequency doubling processes.......We analyze the emission patterns in the process of second harmonic (SH) generation in χ(2) nonlinear gratings and identify for the first time, to the best of our knowledge, the evidence of Raman-Nath type nonlinear diffraction in frequency doubling processes....

  3. Calculation of Smith-Purcell radiation from a volume strip grating

    International Nuclear Information System (INIS)

    Kube, G.

    2005-01-01

    Smith-Purcell radiation is generated by a charged particle beam passing close to the surface of a diffraction grating. Experimental investigations show a strong dependency of the emitted radiation intensity on the form of the grating profile. This influence is expressed by the radiation factor which is a measure of the grating efficiency, in close analogy to reflection coefficients of optical grating theories. The radiation factor depends on beam energy and observation geometry. Up to now calculations for radiation factors exist for lamellar, sinusoidal and echelette-type grating profiles. In this paper, calculations of Smith-Purcell radiation factors for volume strip gratings which are separated by vacuum gaps are presented. They are based on the modal expansion method and restricted to perfectly conducting grating surfaces and to electron trajectories perpendicular to the grating grooves. An infinite system of coupled linear algebraic equations for the scattered and the transmitted wave amplitudes is derived by imposing the continuity condition at the open end of the grooves, and by the boundary conditions at the remaining part of the interface. Numerical results are presented and discussed in view of using Smith-Purcell radiation for particle beam diagnostic purposes

  4. Critical-angle transmission grating technology development for high resolving power soft x-ray spectrometers on Arcus and Lynx

    Science.gov (United States)

    Heilmann, Ralf K.; Bruccoleri, Alexander R.; Song, Jungki; Kolodziejczak, Jeffery; Gaskin, Jessica A.; O'Dell, Stephen L.; Cheimetz, Peter; Hertz, Edward; Smith, Randall K.; Burwitz, Vadim; Hartner, Gisela; La Caria, Marlis-Madeleine; Schattenburg, Mark L.

    2017-08-01

    Soft x-ray spectroscopy with high resolving power (R = λ/Δλ) and large effective area (A) addresses numerous unanswered science questions about the physical laws that lead to the structure of our universe. In the soft x-ray band R > 1000 can currently only be achieved with diffraction grating-based spectroscopy. Criticalangle transmission (CAT) gratings combine the advantages of blazed reflection gratings (high efficiency, use of higher diffraction orders) with those of conventional transmission gratings (relaxed alignment tolerances and temperature requirements, transparent at higher energies, low mass), resulting in minimal mission resource requirements, while greatly improving figures of merit. Diffraction efficiency > 33% and R > 10, 000 have been demonstrated for CAT gratings. Last year the technology has been certified at Technology Readiness Level 4 based on a probe class mission concept. The Explorer-scale (A > 450 cm2 , R > 2500) grating spectroscopy Arcus mission can be built with today's CAT grating technology and has been selected in the current Explorer round for a Phase A concept study. Its figure of merit for the detection of weak absorption lines will be an order of magnitude larger than current instruments on Chandra and XMM-Newton. Further CAT grating technology development and improvements in the angular resolution of x-ray optics can provide another order of magnitude improvement in performance, as is envisioned for the X-ray Surveyor/Lynx mission concept currently under development for input into the 2020 Decadal Survey. For Arcus we have tested CAT gratings in a spectrometer setup in combination with silicon pore optics (SPO) and obtained resolving power results that exceed Arcus requirements before and after environmental testing of the gratings. We have recently fabricated the largest (32 mm x 32 mm) CAT gratings to date, and plan to increase grating size further. We mounted two of these large gratings to frames and aligned them in the

  5. Fiber Optic Long Period Grating Based Sensor for Coconut Oil Adulteration Detection

    Directory of Open Access Journals (Sweden)

    T. M. Libish

    2010-03-01

    Full Text Available We report the development and demonstration of a Long-Period Grating (LPG based optical fiber sensor for determining the adulteration of coconut oil by palm oil. The fundamental principle of detection is the sensitive dependence of the resonance peaks of LPG on the changes of the refractive index of the environmental medium around the cladding surface of the grating. Refractive index sensing with LPGs employs light coupling between core and cladding modes in the grating section. The transmittance spectra of a long period grating element immersed in different mixtures of coconut oil and palm oil were recorded. Results show that resonance wavelengths and transmission intensities varied as a function of the adulteration level of coconut oil. Detection limit of adulteration was found to be 2 % for coconut oil–palm oil binary mixture.

  6. Optical Orbital Angular Momentum Demultiplexing and Channel Equalization by Using Equalizing Dammann Vortex Grating

    Directory of Open Access Journals (Sweden)

    Mingyang Su

    2017-01-01

    Full Text Available A novel equalizing Dammann vortex grating (EDVG is proposed as orbital angular momentum (OAM multiplexer to realize OAM signal demultiplexing and channel equalization. The EDVG is designed by suppressing odd diffraction orders and adjusting the grating structure. The light intensity of diffraction is subsequently distributed evenly in the diffraction orders, and the total diffraction efficiency can be improved from 53.22% to 82%. By using the EDVG, OAM demultiplexing and channel equalization can be realized. Numerical simulation shows that the bit error rate (BER of each OAM channel can decrease to 10-4 when the bit SNR is 22 dB, and the intensity is distributed over the necessary order of diffraction evenly.

  7. Fabrication of Polymer Optical Fibre (POF) Gratings.

    Science.gov (United States)

    Luo, Yanhua; Yan, Binbin; Zhang, Qijin; Peng, Gang-Ding; Wen, Jianxiang; Zhang, Jianzhong

    2017-03-04

    Gratings inscribed in polymer optical fibre (POF) have attracted remarkable interest for many potential applications due to their distinctive properties. This paper overviews the current state of fabrication of POF gratings since their first demonstration in 1999. In particular we summarize and discuss POF materials, POF photosensitivity, techniques and issues of fabricating POF gratings, as well as various types of POF gratings.

  8. Diffraction gauging

    International Nuclear Information System (INIS)

    Wilkens, P.H.

    1978-01-01

    This system of gauging is now being designed to fit on an Excello NC lathe to measure the form, accuracy, and size of external contoured surfaces as they approach the finish machined size. A template profile of the finished workpiece, but 0.003 in. bigger on radius, will be aligned with the workpiece using a reference diameter and face on the machining fixture to leave a gap between the profile of the template and workpiece. A helium--neon laser beam will be projected through this gap using a rotating retroreflector and a fixed laser. The resulting diffraction pattern produced by the laser beam passing through the template to workpiece gap will be reflected and focused on a fixed diode array via a second retroreflector which moves and remains in optical alignment with the first. These retroreflectors will be rotated about a center that will enable the laser beam, which is shaped in a long slit, to scan the template workpiece gap from the pole to the equator of the workpiece. The characteristic diffraction pattern will be detected by the fixed diode array, and the signal levels from this array will be processed in a mini-computer programmed to produce a best fit through the two minima of the diode signals. The separation of the two minima will yield the size of the workpiece to template gap and this information will be presented to the machine tool operator

  9. Volume phase holographic gratings for the Subaru Prime Focus Spectrograph: performance measurements of the prototype grating set

    Science.gov (United States)

    Barkhouser, Robert H.; Arns, James; Gunn, James E.

    2014-08-01

    The Prime Focus Spectrograph (PFS) is a major instrument under development for the 8.2 m Subaru telescope on Mauna Kea. Four identical, fixed spectrograph modules are located in a room above one Nasmyth focus. A 55 m fiber optic cable feeds light into the spectrographs from a robotic fiber positioner mounted at the telescope prime focus, behind the wide field corrector developed for Hyper Suprime-Cam. The positioner contains 2400 fibers and covers a 1.3 degree hexagonal field of view. Each spectrograph module will be capable of simultaneously acquiring 600 spectra. The spectrograph optical design consists of a Schmidt collimator, two dichroic beamsplitters to separate the light into three channels, and for each channel a volume phase holographic (VPH) grating and a dual- corrector, modified Schmidt reimaging camera. This design provides a 275 mm collimated beam diameter, wide simultaneous wavelength coverage from 380 nm to 1.26 µm, and good imaging performance at the fast f/1.1 focal ratio required from the cameras to avoid oversampling the fibers. The three channels are designated as the blue, red, and near-infrared (NIR), and cover the bandpasses 380-650 nm (blue), 630-970 nm (red), and 0.94-1.26 µm (NIR). A mosaic of two Hamamatsu 2k×4k, 15 µm pixel CCDs records the spectra in the blue and red channels, while the NIR channel employs a 4k×4k, substrate-removed HAWAII-4RG array from Teledyne, with 15 µm pixels and a 1.7 µm wavelength cutoff. VPH gratings have become the dispersing element of choice for moderate-resolution astronomical spectro- graphs due their potential for very high diffraction efficiency, low scattered light, and the more compact instru- ment designs offered by transmissive dispersers. High quality VPH gratings are now routinely being produced in the sizes required for instruments on large telescopes. These factors made VPH gratings an obvious choice for PFS. In order to reduce risk to the project, as well as fully exploit the performance

  10. Soft x-ray blazed transmission grating spectrometer with high resolving power and extended bandpass

    Science.gov (United States)

    Heilmann, Ralf K.; Bruccoleri, Alexander Robert; Schattenburg, Mark

    2016-04-01

    A number of high priority questions in astrophysics can be addressed by a state-of-the-art soft x-ray grating spectrometer, such as the role of Active Galactic Nuclei in galaxy and star formation, characterization of the Warm-Hot Intergalactic Medium and the “missing baryon” problem, characterization of halos around the Milky Way and nearby galaxies, as well as stellar coronae and surrounding winds and disks. An Explorer-scale, large-area (> 1,000 cm2), high resolving power (R = λ/Δλ > 3,000) soft x-ray grating spectrometer is highly feasible based on Critical-Angle Transmission (CAT) grating technology. Still significantly higher performance can be provided by a CAT grating spectrometer on an X-ray-Surveyor-type mission. CAT gratings 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) with minimal mission resource requirements. They are high-efficiency blazed transmission gratings that consist of freestanding, ultra-high aspect-ratio grating bars fabricated from silicon-on-insulator (SOI) wafers using advanced anisotropic dry and wet etch techniques. Blazing is achieved through grazing-incidence reflection off the smooth grating bar sidewalls. The reflection properties of silicon are well matched to the soft x-ray band. Nevertheless, CAT gratings with sidewalls made of higher atomic number elements allow extension of the CAT grating principle to higher energies and larger dispersion angles. We show x-ray data from metal-coated CAT gratings and demonstrate efficient blazing to higher energies and larger blaze angles than possible with silicon alone. We also report on measurements of the resolving power of a breadboard CAT grating spectrometer consisting of a Wolter-I slumped-glass focusing mirror pair from Goddard Space Flight Center and CAT gratings, to be

  11. Fiber Grating Environmental Sensing System

    Science.gov (United States)

    Schulz, Whitten L.; Udd, Eric

    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.

  12. MEMS Bragg grating force sensor

    DEFF Research Database (Denmark)

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

    2011-01-01

    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. © 2011 Optical Society of America....

  13. The use of diffraction efficiency theory in the design of soft x-ray monochromators

    International Nuclear Information System (INIS)

    Padmore, H.A.; Martynov, V.; Hollis, K.; Mount Vernon Hospital, Northwood

    1993-01-01

    In general, the diffraction efficiency of gratings is limited by the constraints imposed by the type of geometry used to scan the photon energy. In the simplest example, the spherical grating monochromator (SGM), the deviation angle, the grating groove width and depth and the groove density are all constrained by considerations of the maximum photon energy and the tuning range for individual gratings. We have examined the case in which these parameters are unconstrained, resulting in predictions of the ultimate performance of lamellar type gratings for groove densities from 300 to 2400 1/mm for gold and nickel coatings. The differential method of Neviere et al was used for modeling the behavior of the gratings and justification is presented for this by rigorous comparison with measurements. The implications of these results for future monochromators based on a variable included angle geometry are discussed

  14. Self-diffraction of continuous laser radiation in a disperse medium with absorbing particles

    DEFF Research Database (Denmark)

    Angelsky, O. V.; Bekshaev, A. Ya.; Maksimyak, P. P.

    2013-01-01

    We study the self-action of light in a water suspension of absorbing subwavelength particles. Due to efficient accumulation of the light energy, this medium shows distinct non-linear properties even at moderate radiation power. In particular, by means of interference of two obliquely incident beams......, it is possible to create controllable phase and amplitude gratings whose contrast, spatial and temporal parameters depend on the beams' coherence and power as well as the interference geometry. The grating characteristics are investigated via the beams' self-diffraction. The main mechanism of the grating...... formation is shown to be thermal, which leads to the phase grating; a weak amplitude grating also emerges due to the particles' displacements caused by the light-induced gradient and photophoretic forces. These forces, together with the Brownian motion of the particles, are responsible for the grating...

  15. Diffractive flat panel solar concentrators of a novel design.

    Science.gov (United States)

    de Jong, Ties M; de Boer, Dick K G; Bastiaansen, Cees W M

    2016-07-11

    A novel design for a flat panel solar concentrator is presented which is based on a light guide with a grating applied on top that diffracts light into total internal reflection. By combining geometrical and diffractive optics the geometrical concentration ratio is optimized according to the principles of nonimaging optics, while the thickness of the device is minimized due to the use of total internal reflection.

  16. Grating exchange system of independent mirror supported by floating rotary stage

    Science.gov (United States)

    Zhang, Jianhuan; Tao, Jin; Liu, Yan; Nan, Yan

    2015-10-01

    The performance of The Grating Exchange System can satisfy the Thirty Meter Telescope - TMT for astronomical observation WFOS index requirements and satisfy the requirement of accuracy in the grating exchange. It is used to install in the MOBIE and a key device of MOBIE. The Wide Field Optical Spectrograph (WFOS) is one of the three first-light observing capabilities selected by the TMT Science Advisory Committee. The Multi-Object Broadband Imaging Echellette (MOBIE) instrument design concept has been developed to address the WFOS requirements as described in the TMT Science-Based Requirements Document (SRD). The Grating Exchange System uses a new type of separate movement way of three grating devices and a mirror device. Three grating devices with a mirror are able to achieve independence movement. This kind of grating exchange system can effectively solve the problem that the volume of the grating change system is too large and that the installed space of MOBIE instruments is too limit. This system adopts the good stability, high precision of rotary stage - a kind of using air bearing (Air bearing is famous for its ultra-high precision, and can meet the optical accuracy requirement) and rotation positioning feedback gauge turntable to support grating device. And with a kind of device which can carry greater weight bracket fixed on the MOBIE instrument, with two sets of servo motor control rotary stage and the mirror device respectively. And we use the control program to realize the need of exercising of the grating device and the mirror device. Using the stress strain analysis software--SolidWorks for stress and strain analysis of this structure. And then checking the structure of the rationality and feasibility. And prove that this system can realize the positioning precision under different working conditions can meet the requirements of imaging optical grating diffraction efficiency and error by the calculation and optical performance analysis.

  17. X-ray verification of an optically-aligned off-plane grating module

    Science.gov (United States)

    Donovan, Benjamin; McEntaffer, Randall; Tutt, James; DeRoo, Casey; Allured, Ryan; Gaskin, Jessica; Kolodziejczak, Jeffery

    2017-08-01

    The next generation of X-ray spectrometer missions are baselined to have order-of-magnitude improvements in both spectral resolving power and effective area when compared to existing X-ray spectrometer missions. Off-plane X-ray reflection gratings are capable of achieving high resolution and high diffraction efficiencies over the entire X-ray bandpass, making them an ideal technology to implement on these future missions. To achieve the high effective area desired while maintaining high spectral resolution, many off-plane gratings must be precisely aligned such that their diffraction arcs overlap at the focal plane. Methods are under development to align a number of these gratings into a grating module using optical metrology techniques in support of the Off-plane Grating Rocket Experiment (OGRE), a suborbital rocket payload scheduled to launch in late 2018. X-ray testing was performed on an aligned grating module at the Straylight Test Facility (SLTF) at NASA Marshall Space Flight Center (MSFC) to assess the current alignment methodology and its ability to meet the desired performance of OGRE. We report on the results from the test campaign at MSFC, as well as plans for future development.

  18. Simulation Studies of the Dielectric Grating as an Accelerating and Focusing Structure

    International Nuclear Information System (INIS)

    Soong, Ken; Peralta, E.A.; Byer, R.L.; Colby, E.

    2011-01-01

    A grating-based design is a promising candidate for a laser-driven dielectric accelerator. Through simulations, we show the merits of a readily fabricated grating structure as an accelerating component. Additionally, we show that with a small design perturbation, the accelerating component can be converted into a focusing structure. The understanding of these two components is critical in the successful development of any complete accelerator. The concept of accelerating electrons with the tremendous electric fields found in lasers has been proposed for decades. However, until recently the realization of such an accelerator was not technologically feasible. Recent advances in the semiconductor industry, as well as advances in laser technology, have now made laser-driven dielectric accelerators imminent. The grating-based accelerator is one proposed design for a dielectric laser-driven accelerator. This design, which was introduced by Plettner, consists of a pair of opposing transparent binary gratings, illustrated in Fig. 1. The teeth of the gratings serve as a phase mask, ensuring a phase synchronicity between the electromagnetic field and the moving particles. The current grating accelerator design has the drive laser incident perpendicular to the substrate, which poses a laser-structure alignment complication. The next iteration of grating structure fabrication seeks to monolithically create an array of grating structures by etching the grating's vacuum channel into a fused silica wafer. With this method it is possible to have the drive laser confined to the plane of the wafer, thus ensuring alignment of the laser-and-structure, the two grating halves, and subsequent accelerator components. There has been previous work using 2-dimensional finite difference time domain (2D-FDTD) calculations to evaluate the performance of the grating accelerator structure. However, this work approximates the grating as an infinite structure and does not accurately model a

  19. Determination of chemical concentration with a 2 dimensional CCD array in the Echelle grating spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, D.K. [Lawrence Livermore National Lab., CA (United States); Stevens, C.G.

    1994-11-15

    The Echelle grating spectrometer (EGS) uses a stepped Echelle grating, prisms and a folded light path to miniaturize an infrared spectrometer. Light enters the system through a slit and is spread out along Y by a prism. This light then strikes the grating and is diffracted out along X. This spreading results in a superposition of spectral orders since the grating has a high spectral range. These orders are then separated by again passing through a prism. The end result of a measurement is a 2 dimensional image which contains the folded spectrum of the region under investigation. The data lies in bands from top to bottom, for example, with wavenumber increments as small as 0.1 lying from left to right such that the right end of band N is the same as the left end of band N+1. This is the image which must be analyzed.

  20. Scanning laser reflection tool for alignment and period measurement of critical-angle transmission gratings

    Science.gov (United States)

    Song, Jungki; Heilmann, Ralf K.; Bruccoleri, Alexander R.; Hertz, Edward; Schatternburg, Mark L.

    2017-08-01

    We report progress toward developing a scanning laser reflection (LR) tool for alignment and period measurement of critical-angle transmission (CAT) gratings. It operates on a similar measurement principle as a tool built in 1994 which characterized period variations of grating facets for the Chandra X-ray Observatory. A specularly reflected beam and a first-order diffracted beam were used to record local period variations, surface slope variations, and grating line orientation. In this work, a normal-incidence beam was added to measure slope variations (instead of the angled-incidence beam). Since normal incidence reflection is not coupled with surface height change, it enables measurement of slope variations more accurately and, along with the angled-incidence beam, helps to reconstruct the surface figure (or tilt) map. The measurement capability of in-grating period variations was demonstrated by measuring test reflection grating (RG) samples that show only intrinsic period variations of the interference lithography process. Experimental demonstration for angular alignment of CAT gratings is also presented along with a custom-designed grating alignment assembly (GAA) testbed. All three angles were aligned to satisfy requirements for the proposed Arcus mission. The final measurement of roll misalignment agrees with the roll measurements performed at the PANTER x-ray test facility.

  1. Mobile display backlight light guide plates based on slanted grating arrays

    Science.gov (United States)

    Kimmel, Jyrki; Levola, Tapani

    2011-05-01

    Modern mobile communication devices have user interfaces that are dominated by high-quality displays. Increased multimedia use imposes high demands on the design of display modules, as the content available for mobile use becomes visually richer. Especially the power dissipation of the display can limit the amount of time available for multimedia consumption and interaction. In the mobile liquid-crystal display (LCD), the energy efficiency is determined by the backlight design. State-of-the-art backlights direct white light through a display subpixel array, with high uniformity and up to 90 % efficiency in white light output. Diffractive backlights have recently been proposed to reduce the power dissipation of the display module, and slanted grating arrays are among the enabling optical features that allow for reduction in power dissipation beyond what is available in the state of the art. By the use of diffractive grating arrays, the required primary color (red, green, or blue) is directed through the LCD subpixel array with geometrical registration, instead of flooding the whole LCD with white light and filtering the primary colors through the subpixel color filter array. This paper presents a study on grating structures based on slanted grating arrays fabricated in high refractive index materials. The grating design and grating outcoupling results are provided, and an outline of a new embedded system design is given. Emphasis is on grating array design aspects for future display system design. The results show that savings in power consumption can be expected with advanced display system design based on embedded slanted grating array backlight light guide plates.

  2. On metallic gratings coated conformally with isotropic negative-phase-velocity materials

    Energy Technology Data Exchange (ETDEWEB)

    Inchaussandague, Marina E. [GEA-Grupo de Electromagnetismo Aplicado, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon I, 1428 Buenos Aires (Argentina); CONICET-Consejo Nacional de Investigaciones Cientificas y Tecnicas, Rivadavia 1917, Buenos Aires (Argentina)], E-mail: mei@df.uba.ar; Lakhtakia, Akhlesh [CATMAS-Computational and Theoretical Materials Sciences Group, Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802-6812 (United States)], E-mail: akhlesh@psu.edu; Depine, Ricardo A. [GEA-Grupo de Electromagnetismo Aplicado, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon I, 1428 Buenos Aires (Argentina); CONICET-Consejo Nacional de Investigaciones Cientificas y Tecnicas, Rivadavia 1917, Buenos Aires (Argentina)], E-mail: rdep@df.uba.ar

    2008-03-31

    Application of the differential method (also called the C method) to plane-wave diffraction by a perfectly conducting, sinusoidally corrugated metallic grating coated with a linear, homogeneous, isotropic, lossless dielectric-magnetic material shows that coating materials with negative index of refraction may deliver enhanced maximum nonspecular reflection efficiencies in comparison to coating materials with positive index of refraction.

  3. Engineered plasmon focusing on functional gratings

    NARCIS (Netherlands)

    Offerhaus, Herman L.; van den Bergen, B; van Hulst, N.F.

    2005-01-01

    We report on the engineering of plasmon propagation and focusing by dedicated curved gratings and noncollinear phasematching. Gratings were created on gold by focused ion beam milling and plasmons were measured using phase sensitive PSTM.

  4. Polymer optical fiber bragg grating sensors

    DEFF Research Database (Denmark)

    Stefani, Alessio; Yuan, Scott Wu; Andresen, Søren

    2010-01-01

    Fiber-optical accelerometers based on polymer optical fiber Bragg gratings are reported. We have written fiber Bragg gratings for 1550 nm and 850 nm operations, characterized their temperature and strain response, and tested their performance in a prototype accelerometer....

  5. State of the art in silicon immersed gratings for space

    Science.gov (United States)

    van Amerongen, Aaldert; Krol, Hélène; Grèzes-Besset, Catherine; Coppens, Tonny; Bhatti, Ianjit; Lobb, Dan; Hardenbol, Bram; Hoogeveen, Ruud

    2017-11-01

    We present the status of our immersed diffraction grating technology, as developed at SRON and of their multilayer optical coatings as developed at CILAS. Immersion means that diffraction takes place inside the medium, in our case silicon. The high refractive index of the silicon medium boosts the resolution and the dispersion. Ultimate control over the groove geometry yields high efficiency and polarization control. Together, these aspects lead to a huge reduction in spectrometer volume. This has opened new avenues for the design of spectrometers operating in the short-wave-infrared wavelength band. Immersed grating technology for space application was initially developed by SRON and TNO for the short-wave-infrared channel of TROPOMI, built under the responsibility of SSTL. This space spectrometer will be launched on ESA's Sentinel 5 Precursor mission in 2015 to monitor pollution and climate gases in the Earth atmosphere. The TROPOMI immersed grating flight model has technology readiness level 8. In this program CILAS has qualified and implemented two optical coatings: first, an anti-reflection coating on the entrance and exit facet of the immersed grating prism, which reaches a very low value of reflectivity for a wide angular range of incidence of the transmitted light; second, a metal-dielectric absorbing coating for the passive facet of the prism to eliminate stray light inside the silicon prism. Dual Ion Beam Sputtering technology with in-situ visible and infrared optical monitoring guarantees the production of coatings which are nearly insensitive to temperature and atmospheric conditions. Spectral measurements taken at extreme temperature and humidity conditions show the reliability of these multi-dielectric and metal-dielectric functions for space environment. As part of our continuous improvement program we are presently developing new grating technology for future missions, hereby expanding the spectral range, the blaze angles and grating size, while

  6. Diffractive generalized phase contrast for adaptive phase imaging and optical security

    DEFF Research Database (Denmark)

    Palima, Darwin; Glückstad, Jesper

    2012-01-01

    We analyze the properties of Generalized Phase Contrast (GPC) when the input phase modulation is implemented using diffractive gratings. In GPC applications for patterned illumination, the use of a dynamic diffractive optical element for encoding the GPC input phase allows for onthe- fly...... optimization of the input aperture parameters according to desired output characteristics. For wavefront sensing, the achieved aperture control opens a new degree of freedom for improving the accuracy of quantitative phase imaging. Diffractive GPC input modulation also fits well with grating-based optical...... security applications and can be used to create phasebased information channels for enhanced information security....

  7. Tunable grating with active feedback

    Science.gov (United States)

    Rosset, Samuel; O'Brien, Benjamin M.; Gisby, Todd; Xu, Daniel; Shea, Herbert R.; Anderson, Iain A.

    2013-04-01

    We report on the use of capacitive self-sensing to operate a DEA-based tunable grating in closed-loop mode. Due to their large strain capabilities, DEAs are key candidates for tunable optics applications. However, the viscoelasticity of elastomers is detrimental for applications that require long-term stability, such as tunable gratings and lenses. We show that capacitive sensing of the electrode strain can be used to suppress the strain drift and increase the response speed of silicone-based actuators. On the other hand, VHB actuators exhibit a time-dependent permittivity, which causes a drift between the device capacitance and its strain.

  8. Fabrication of Polymer Optical Fibre (POF Gratings

    Directory of Open Access Journals (Sweden)

    Yanhua Luo

    2017-03-01

    Full Text Available Gratings inscribed in polymer optical fibre (POF have attracted remarkable interest for many potential applications due to their distinctive properties. This paper overviews the current state of fabrication of POF gratings since their first demonstration in 1999. In particular we summarize and discuss POF materials, POF photosensitivity, techniques and issues of fabricating POF gratings, as well as various types of POF gratings.

  9. Measurement of the thermal diffusivity and speed of sound of hydrothermal solutions via the laser-induced grating technique

    International Nuclear Information System (INIS)

    Butenhoff, T.J.

    1994-01-01

    Hydrothermal processing is being developed as a method for organic destruction for the Hanford Site in Washington. Hydrothermal processing refers to the redox reactions of chemical compounds in supercritical or near-supercritical aqueous solutions. In order to design reactors for the hydrothermal treatment of complicated mixtures found in the Hanford wastes, engineers need to know the thermophysical properties of the solutions under hydrothermal conditions. The author used the laser-induced grating technique to measure the thermal diffusivity and speed of sound of hydrothermal solutions. In this non-invasive optical technique, a transient grating is produced in the hydrothermal solution by optical absorption from two crossed time-coincident nanosecond laser pulses. The grating is probed by measuring the diffraction efficiency of a third laser beam. The grating relaxes via thermal diffusion, and the thermal diffusivity can be determined by measuring the decay of the grating diffraction efficiency as a function of the pump-probe delay time. In addition, intense pump pulses produce counterpropagating acoustic waves that appear as large undulations in the transient grating decay spectrum. The speed of sound in the sample is simply the grating fringe spacing divided by the undulation period. The cell is made from a commercial high pressure fitting and is equipped with two diamond windows for optical access. Results are presented for dilute dye/water solutions with T = 400 C and pressures between 20 and 70 MPa

  10. Hybrid grating reflectors: Origin of ultrabroad stopband

    DEFF Research Database (Denmark)

    Park, Gyeong Cheol; Taghizadeh, Alireza; Chung, Il-Sug

    2016-01-01

    Hybrid grating (HG) reflectors with a high-refractive-index cap layer added onto a high contrast grating (HCG) provide a high reflectance close to 100% over a broader wavelength range than HCGs. The combination of a cap layer and a grating layer brings a strong Fabry-Perot (FP) resonance as well ...

  11. Development of a Novel Spectrophotometer for Biochemical Analyzer Based on Volume Holography Transmissive Grating and Linear CCD

    International Nuclear Information System (INIS)

    Ren Zhong; Liu Guodong; Huang Zhen; Zeng Lvming; Dai Longmin

    2011-01-01

    The classical surface-embossed plane and concave grating are usually used as the diffraction grating in some spectrophotometers. But the minute cracks are produced on the surface of the gratings' grooves, which leads to generate the stray-light and decrease the efficiency of instrument. Therefore, a novel custom-built spectrophotometer for BCA is developed in this paper. Meanwhile, the volume holography transmissive (VHT) grating is used as the diffraction grating in this spectrophotometer. Additionally, a high resolution CCD and data acquisition (DAQ) card with combined the virtual software platform based on LabVIEW are used to design the spectral acquisition and analysis system. Experimental results show that the spectral range and the diffraction efficiency of the spectrophotometer for BCA are greatly increased. The spectral range of the spectrophotometer for BCA can reach 300-1000 nm, its wavelength resolution can reach 1nm. And, it uses the back-splitting-light technology and multi-channel parallel analysis. Compared with other same types, this spectrophotometer has many advantages, such as, higher efficiency, simpler algorithm, higher accuracy, cheaper cost and fewer stray-light and higher imaging quality, etc. Therefore, this spectrophotometer for BCA based on VHT grating will has the greatly potential values in the fields of the biochemical or medical research.

  12. A Broad Iron Line in the Chandra High Energy Transmission Grating Spectrum of 4U 1705-44

    NARCIS (Netherlands)

    di Salvo, T.; Iaria, R.; Méndez, R.M.; Burderi, L.; Lavagetto, G.; Robba, N.R.; Stella, L.; van der Klis, M.

    2005-01-01

    We present the results of a Chandra 30 ks observation of the low-mass X-ray binary and atoll source 4U 1705-44. Here we concentrate on the study of discrete features in the energy spectrum at energies below ~3 keV, as well as on the iron Kalpha line, using the High Energy Transmission Grating

  13. Pressure-induced instability of magnetic order in Kondo-lattice system. Neutron diffraction study of the pseudo-binary alloy system Ce(Ru sub 0 sub . sub 9 sub 0 Rh sub 0 sub . sub 1 sub 0) sub 2 (Si sub 1 sub - sub y Ge sub y) sub 2

    CERN Document Server

    Watanabe, K; Kanadani, C; Taniguchi, T; Kawarazaki, S; Uwatoko, Y; Kadowaki, H

    2003-01-01

    Neutron diffraction experiments have been carried out to study the nature of the magnetic order of the pseudo-binary alloy system Ce(Ru sub 0 sub . sub 9 sub 0 Rh sub 0 sub . sub 1 sub 0) sub 2 (Si sub 1 sub - sub y Ge sub y) sub 2. Response of the ordered atomic magnetic moment, mu, the transition temperature, T sub N , and the magnitude of the magnetic modulation vector, q, to the chemical pressure and also to the applied hydrostatic pressure, P, were examined at low temperatures. When y changes, all of mu, T sub N and q show a sudden alteration of the manner of the y-dependence at around y - 0.08. The P-dependence of q shows quite different features for different y's of 0.0, 0.2 and 0.25. On the basis of these observations the possibility of a pressure-induced alternation of the magnetic regime of the order is discussed. (author)

  14. Hybrid plasmon photonic crystal resonance grating for integrated spectrometer biosensor.

    Science.gov (United States)

    Guo, Hong; Guo, Junpeng

    2015-01-15

    Using nanofabricated hybrid metal-dielectric nanohole array photonic crystal gratings, a hybrid plasmonic optical resonance spectrometer biosensor is demonstrated. The new spectrometer sensor technique measures plasmonic optical resonance from the first-order diffraction rather than via the traditional method of measuring optical resonance from transmission. The resonance spectra measured with the new spectrometer technique are compared with the spectra measured using a commercial optical spectrometer. It is shown that the new optical resonance spectrometer can be used to measure plasmonic optical resonance that otherwise cannot be measured with a regular optical spectrometer.

  15. Spectral analysis in overmodulated holographic reflection gratings recorded with BB640 ultrafine grain emulsion

    Science.gov (United States)

    Mas-Abellán, P.; Madrigal, R.; Fimia, A.

    2015-05-01

    Silver halide emulsions have been considered one of the most energetic sensitive materials for holographic applications. Nonlinear recording effects on holographic reflection gratings recorded on silver halide emulsions have been studied by different authors obtaining excellent experimental results. In this communication specifically we focused our investigation on the effects of refractive index modulation, trying to get high levels of overmodulation. We studied the influence of the grating thickness on the overmodulation and its effects on the transmission spectra for a wide exposure range by use of two different thickness ultrafine grain emulsion BB640, thin films (6 μm) and thick films (9 μm), exposed to single collimated beams using a red He-Ne laser (wavelength 632.8 nm) with Denisyuk configuration obtaining a spatial frequency of 4990 l/mm recorded on the emulsion. The experimental results show that high overmodulation levels of refractive index could offer some benefits such as high diffraction efficiency (reaching 90 %), increase of grating bandwidth (close to 80 nm), making lighter holograms, or diffraction spectra deformation, transforming the spectrum from sinusoidal to approximation of square shape. Based on these results, we demonstrate that holographic reflection gratings spectra recorded with overmodulation of refractive index is formed by the combination of several non-linear components due to very high overmodulation. This study is the first step to develop a new easy multiplexing technique based on the use of high index modulation reflection gratings.

  16. Curved VPH gratings for novel spectrographs

    Science.gov (United States)

    Clemens, J. Christopher; O'Donoghue, Darragh; Dunlap, Bart H.

    2014-07-01

    The introduction of volume phase holographic (VPH) gratings into astronomy over a decade ago opened new possibilities for instrument designers. In this paper we describe an extension of VPH grating technology that will have applications in astronomy and beyond: curved VPH gratings. These devices can disperse light while simultaneously correcting aberrations. We have designed and manufactured two different kinds of convex VPH grating prototypes for use in off-axis reflecting spectrographs. One type functions in transmission and the other in reflection, enabling Offnerstyle spectrographs with the high-efficiency and low-cost advantages of VPH gratings. We will discuss the design process and the tools required for modelling these gratings along with the recording layout and process steps required to fabricate them. We will present performance data for the first convex VPH grating produced for an astronomical spectrograph.

  17. Point-by-point written fiber-Bragg gratings and their application in complex grating designs.

    Science.gov (United States)

    Marshall, Graham D; Williams, Robert J; Jovanovic, Nemanja; Steel, M J; Withford, Michael J

    2010-09-13

    The point-by-point technique of fabricating fibre-Bragg gratings using an ultrafast laser enables complete control of the position of each index modification that comprises the grating. By tailoring the local phase, amplitude and spacing of the grating's refractive index modulations it is possible to create gratings with complex transmission and reflection spectra. We report a series of grating structures that were realized by exploiting these flexibilities. Such structures include gratings with controlled bandwidth, and amplitude- and phase-modulated sampled (or superstructured) gratings. A model based on coupled-mode theory provides important insights into the manufacture of such gratings. Our approach offers a quick and easy method of producing complex, non-uniform grating structures in both fibres and other mono-mode waveguiding structures.

  18. Note: Optimization of magnifying a polarization angle with Littrow layout blazed gratings.

    Science.gov (United States)

    Sasao, H; Arakawa, H; Imazawa, R; Kawano, Y; Itami, K; Kubo, H

    2017-03-01

    Magnification of a polarization angle with Littrow layout gratings has been developed. High magnification with a factor of 7.7 using two gratings in Littrow layout was experimentally proved. The magnification range was investigated by calculation at a wavelength of 10.6 μm. The method can be applied for a high magnification factor >30. Larger groove numbers and smaller blaze angles are suitable for the large magnification. Statistical fluctuation of the diffracted polarization angle is compared with that of the incident polarization angle.

  19. Design of a grating for studying Smith-Purcell radiation and electron acceleration

    International Nuclear Information System (INIS)

    Fernow, R.C.

    1989-01-01

    We describe work on the design of a diffraction grating which we intend to use for studying the production of Smith-Purcell radiation and the acceleration of electrons. We have developed computer codes based on the solution of the appropriate Maxwell's equations. A specific grating profile is given which is feasible to construct and which supports enhanced surface accelerating modes. We examine the possibility of using the Smith-Purcell effect to make a beam position monitor. 13 refs., 10 figs., 2 tabs

  20. A directly cooled grating substrate for ALS [Advanced Light Source] undulator beam lines

    International Nuclear Information System (INIS)

    DiGennaro, R.; Swain, T.

    1989-08-01

    Design analyses using finite element methods are presented for thermal distortion of water-cooled diffraction grating substrates for a potential application at the LBL Advanced Light Source, demonstrating that refinements in cooling channel configuration and heat flux distribution can significantly reduce optical surface distortion with high heat loads. Using an existing grating substrate design, sensitivity of tangential slope errors due to thermal distortion is evaluated for a variety of thermal boundary conditions, including coolant flow rate and heat transfer film coefficients, surface illumination area and heat distribution profile, and location of the convection cooling surfaces adjacent to the heated region. 1 ref., 5 figs., 2 tabs

  1. Plasmonic wavelength splitter based on a large-area dielectric grating and white light illumination.

    Science.gov (United States)

    Song, Jae-Chul; Jung, Woo Kyung; Kim, Nak-Hyeon; Byun, Kyung Min

    2012-09-15

    An optical process by which transmission wavelengths can be divided selectively by changing a resonance condition of surface plasmons (SPs) is demonstrated. When white light is incident to an SP resonance substrate with a dielectric grating, SP waves are excited at resonance and transmitted into the air via diffraction by a large-area grating pattern fabricated by nanoimprint lithography. While only a limited range of certain wavelengths is allowed to transmit, the peak transmission wavelength can be tuned continuously in the visible band. We also show that multiple wavelengths are transmitted into different directions simultaneously by using a wedge-shaped white light.

  2. Soft x-ray transmission grating spectrometer for X-ray Surveyor and smaller missions with high resolving power

    Science.gov (United States)

    Heilmann, Ralf K.; Bruccoleri, Alexander; Schattenburg, Mark; Kolodziejczak, jeffery; Gaskin, Jessica; O'Dell, Stephen L.

    2017-01-01

    A number of high priority subjects in astrophysics are addressed by a state-of-the-art soft x-ray grating spectrometer, e.g. the role of Active Galactic Nuclei in galaxy and star formation, characterization of the WHIM and the “missing baryon” problem, characterization of halos around the Milky Way and nearby galaxies, and stellar coronae and surrounding winds and disks. An Explorer-scale, large-area (A > 1,000 cm2), high resolving power (R > 3,000) soft x-ray grating spectrometer is highly feasible based on Critical-Angle Transmission (CAT) grating technology, even for telescopes with angular resolution of 5-10 arcsec. Significantly higher performance could be provided by a CAT grating spectrometer on an X-ray-Surveyor-type mission (A > 4,000 cm2, R > 5,000). CAT gratings combine advantages of blazed reflection gratings (high efficiency, use of higher orders) with those of transmission gratings (low mass, relaxed alignment tolerances and temperature requirements, transparent at higher energies) with minimal mission resource requirements. Blazing is achieved through grazing-incidence reflection off the smooth silicon grating bar sidewalls. Silicon is well matched to the soft x-ray band, and 30% absolute diffraction efficiency has been acheived with clear paths for further improvement. CAT gratings with sidewalls made of high-Z elements allow extension of blazing to higher energies and larger dispersion angles, enabling higher resolving power at shorter wavelengths. X-ray data from CAT gratings coated with a thin layer of platinum using atomic layer deposition demonstrate efficient blazing to higher energies and much larger blaze angles than possible with silicon alone. Measurements of the resolving power of a breadboard CAT grating spectrometer consisting of a Wolter-I slumped-glass focusing optic from GSFC and CAT gratings, taken at the MSFC Stray Light Facility, have demonstrated resolving power > 10,000. Thus currently fabricated CAT gratings are compatible

  3. Two-dimensional higher-diffraction-order optical beam splitter based on phenanthrenequinone-doped poly(methyl methacrylate) photopolymer

    Science.gov (United States)

    Gong, Dewei; Zhou, Zhongxiang; Liu, Hongpeng; Wang, Jian; Gao, Hongyue

    2009-06-01

    A two-dimensional optical beam splitter has been realized that uses the higher diffraction orders of a refractive-index grating. Gratings were recorded experimentally with light from a semiconductor laser incident at a small angle on phenanthrenequinone-doped poly(methyl methacrylate) photopolymer. The incident signal beam, which was made up of three different wavelengths (632.8, 532.0, and 488.0 nm), was split by the grating into multiple output beams with nearly equal size and separation. Results are given for when the sample grating was placed behind, in front of, and in the focal plane of a Fourier lens. The properties of higher-order-diffraction images have been discussed. The discussion shows that a two-dimensional higher-diffraction-order optical beam splitter provides a practical method for splitting a signal beam.

  4. Solving a binary puzzle

    NARCIS (Netherlands)

    P.H. Utomo (Putranto); R.H. Makarim (Rusydi)

    2017-01-01

    textabstractA Binary puzzle is a Sudoku-like puzzle with values in each cell taken from the set (Formula presented.). Let (Formula presented.) be an even integer, a solved binary puzzle is an (Formula presented.) binary array that satisfies the following conditions: (1) no three consecutive ones and

  5. Eclipsing binaries in open clusters

    DEFF Research Database (Denmark)

    Southworth, John; Clausen, J.V.

    2006-01-01

    Stars: fundamental parameters - Stars : binaries : eclipsing - Stars: Binaries: spectroscopic - Open clusters and ass. : general Udgivelsesdato: 5 August......Stars: fundamental parameters - Stars : binaries : eclipsing - Stars: Binaries: spectroscopic - Open clusters and ass. : general Udgivelsesdato: 5 August...

  6. Surface diffusion studies by optical diffraction techniques

    International Nuclear Information System (INIS)

    Xiao, X.D.

    1992-11-01

    The newly developed optical techniques have been combined with either second harmonic (SH) diffraction or linear diffraction off a monolayer adsorbate grating for surface diffusion measurement. Anisotropy of surface diffusion of CO on Ni(l10) was used as a demonstration for the second harmonic dim reaction method. The linear diffraction method, which possesses a much higher sensitivity than the SH diffraction method, was employed to study the effect of adsorbate-adsorbate interaction on CO diffusion on Ni(l10) surface. Results showed that only the short range direct CO-CO orbital overlapping interaction influences CO diffusion but not the long range dipole-dipole and CO-NI-CO interactions. Effects of impurities and defects on surface diffusion were further explored by using linear diffraction method on CO/Ni(110) system. It was found that a few percent S impurity can alter the CO diffusion barrier height to a much higher value through changing the Ni(110) surface. The point defects of Ni(l10) surface seem to speed up CO diffusion significantly. A mechanism with long jumps over multiple lattice distance initiated by CO filled vacancy is proposed to explain the observed defect effect

  7. Feasibility evaluation of a neutron grating interferometer with an analyzer grating based on a structured scintillator

    Science.gov (United States)

    Kim, Youngju; Kim, Jongyul; Kim, Daeseung; Hussey, Daniel. S.; Lee, Seung Wook

    2018-03-01

    We introduce an analyzer grating based on a structured scintillator fabricated by a gadolinium oxysulfide powder filling method for a symmetric Talbot-Lau neutron grating interferometer. This is an alternative way to analyze the Talbot self-image of a grating interferometer without using an absorption grating to block neutrons. Since the structured scintillator analyzer grating itself generates the signal for neutron detection, we do not need an additional scintillator screen as an absorption analyzer grating. We have developed and tested an analyzer grating based on a structured scintillator in our symmetric Talbot-Lau neutron grating interferometer to produce high fidelity absorption, differential phase, and dark-field contrast images. The acquired images have been compared to results of a grating interferometer utilizing a typical absorption analyzer grating with two commercial scintillation screens. The analyzer grating based on the structured scintillator enhances interference fringe visibility and shows a great potential for economical fabrication, compact system design, and so on. We report the performance of the analyzer grating based on a structured scintillator and evaluate its feasibility for the neutron grating interferometer.

  8. Diffraction-based BioCD biosensor for point-of-care diagnostics

    Science.gov (United States)

    Choi, H.; Chang, C.; Savran, C.; Nolte, D.

    2018-02-01

    The BioCD platform technology uses spinning-disk interferometry to detect molecular binding to target molecular probes in biological samples. Interferometric configurations have included differential phase contrast and in-line quadrature detection. For the detection of extremely low analyte concentrations, nano- or microparticles can enhance the signal through background-free diffraction detection. Diffraction signal measurements on BioCD biosensors are achieved by forming gratings on a disc surface. The grating pattern was printed with biotinylated bovine serum albumin (BSA) and streptavidin coated beads were deployed. The diameter of the beads was 1 micron and strong protein bonding occurs between BSA and streptavidin-coated beads at the printed location. The wavelength for the protein binding detection was 635 nm. The periodic pattern on the disc amplified scattered light into the first-order diffraction position. The diffracted signal contains Mie scattering and a randomly-distributed-bead noise contributions. Variation of the grating pattern periodicity modulates the diffraction efficiency. To test multiple spatial frequencies within a single scan, we designed a fan-shaped grating to perform frequency filter multiplexing on a diffraction-based BioCD.

  9. Development and calibration of mirrors and gratings for the soft x-ray materials science beamline at the Linac Coherent Light Source free-electron laser.

    Science.gov (United States)

    Soufli, Regina; Fernández-Perea, Mónica; Baker, Sherry L; Robinson, Jeff C; Gullikson, Eric M; Heimann, Philip; Yashchuk, Valeriy V; McKinney, Wayne R; Schlotter, William F; Rowen, Michael

    2012-04-20

    This work discusses the development and calibration of the x-ray reflective and diffractive elements for the Soft X-ray Materials Science (SXR) beamline of the Linac Coherent Light Source (LCLS) free-electron laser (FEL), designed for operation in the 500 to 2000 eV region. The surface topography of three Si mirror substrates and two Si diffraction grating substrates was examined by atomic force microscopy (AFM) and optical profilometry. The figure of the mirror substrates was also verified via surface slope measurements with a long trace profiler. A boron carbide (B4C) coating especially optimized for the LCLS FEL conditions was deposited on all SXR mirrors and gratings. Coating thickness uniformity of 0.14 nm root mean square (rms) across clear apertures extending to 205 mm length was demonstrated for all elements, as required to preserve the coherent wavefront of the LCLS source. The reflective performance of the mirrors and the diffraction efficiency of the gratings were calibrated at beamline 6.3.2 at the Advanced Light Source synchrotron. To verify the integrity of the nanometer-scale grating structure, the grating topography was examined by AFM before and after coating. This is to our knowledge the first time B4C-coated diffraction gratings are demonstrated for operation in the soft x-ray region.

  10. Diffraction analysis for DMD-based scene projectors in the long-wave infrared.

    Science.gov (United States)

    Han, Qing; Zhang, Jianzhong; Wang, Jian; Sun, Qiang

    2016-10-01

    Diffraction effects play a significant role in the digital micromirror device (DMD)-based scene projectors in the long-wave infrared (IR) band (8-12 μm). The contrast provided by these projector systems can become noticeably worse because of the diffraction characteristics of the DMD. We apply a diffraction grating model of the DMD based on the scalar diffraction theory and the Fourier transform to address this issue. In addition, a simulation calculation is conducted with MATLAB. Finally, the simulation result is verified with an experiment. The simulation and experimental results indicate that, when the incident azimuth angle is 0° and the zenith angle is between 42°and 46°, the scene projectors will have a good imaging contrast in the long-wave IR. The diffraction grating model proposed in this study provides a method to improve the contrast of DMD-based scene projectors in the long-wave IR.

  11. Nanoporous Polymeric Grating-Based Biosensors

    KAUST Repository

    Gao, Tieyu

    2012-05-02

    We demonstrate the utilization of an interferometrically created nanoporous polymeric gratings as a platform for biosensing applications. Aminopropyltriethoxysilane (APTES)-functionalized nanoporous polymeric gratings was fabricated by combining holographic interference patterning and APTES-functionalization of pre-polymer syrup. The successful detection of multiple biomolecules indicates that the biofunctionalized nanoporous polymeric gratings can act as biosensing platforms which are label-free, inexpensive, and applicable as high-throughput assays. Copyright © 2010 by ASME.

  12. Improved Resolution Optical Time Stretch Imaging Based on High Efficiency In-Fiber Diffraction.

    Science.gov (United States)

    Wang, Guoqing; Yan, Zhijun; Yang, Lei; Zhang, Lin; Wang, Chao

    2018-01-12

    Most overlooked challenges in ultrafast optical time stretch imaging (OTSI) are sacrificed spatial resolution and higher optical loss. These challenges are originated from optical diffraction devices used in OTSI, which encode image into spectra of ultrashort optical pulses. Conventional free-space diffraction gratings, as widely used in existing OTSI systems, suffer from several inherent drawbacks: limited diffraction efficiency in a non-Littrow configuration due to inherent zeroth-order reflection, high coupling loss between free-space gratings and optical fibers, bulky footprint, and more importantly, sacrificed imaging resolution due to non-full-aperture illumination for individual wavelengths. Here we report resolution-improved and diffraction-efficient OTSI using in-fiber diffraction for the first time to our knowledge. The key to overcome the existing challenges is a 45° tilted fiber grating (TFG), which serves as a compact in-fiber diffraction device offering improved diffraction efficiency (up to 97%), inherent compatibility with optical fibers, and improved imaging resolution owning to almost full-aperture illumination for all illumination wavelengths. 50 million frames per second imaging of fast moving object at 46 m/s with improved imaging resolution has been demonstrated. This conceptually new in-fiber diffraction design opens the way towards cost-effective, compact and high-resolution OTSI systems for image-based high-throughput detection and measurement.

  13. Design of a novel transmission-grating spectrometer for soft X-ray emission studies

    Energy Technology Data Exchange (ETDEWEB)

    Hatsui, Takaki [Institute for Molecular Science, Myodaiji, Okazaki 444-8585 (Japan) and Graduate School for Advanced Studies, Myodaiji, Okazaki 444-8585 (Japan)]. E-mail: hatsui@ims.ac.jp; Setoyama, Hiroyuki [Institute for Molecular Science, Myodaiji, Okazaki 444-8585 (Japan); Shigemasa, Eiji [Institute for Molecular Science, Myodaiji, Okazaki 444-8585 (Japan); Graduate School for Advanced Studies, Myodaiji, Okazaki 444-8585 (Japan); Kosugi, Nobuhiro [Institute for Molecular Science, Myodaiji, Okazaki 444-8585 (Japan); Graduate School for Advanced Studies, Myodaiji, Okazaki 444-8585 (Japan)

    2005-06-15

    The design of a transmission-grating spectrometer for high-resolution soft X-ray emission studies has been proposed. It is different from conventional types of soft X-ray emission spectrometers; that is, the spectrometer has a Wolter type I mirror, a free-standing transmission grating, and a back-illuminated CCD. A high collection angle up to 1.5 x 10{sup -3} sr is achieved by utilizing the Wolter mirror as a prefocusing system. The CCD is mounted at 1400 mm downstream of the grating on a Rowland torus mount. Diffracted X-rays are detected by the CCD in the normal incidence geometry, resulting in high detection efficiency. The energy resolution is limited by the figure errors of the optical elements and the spatial resolution of the detector. The ray-tracing results confirm that the aberrations do not practically degrade the energy resolution.

  14. Resonant transmission and mode modulation of acoustic waves in H-shaped metallic gratings

    International Nuclear Information System (INIS)

    Deng, Yu-Qiang; Fan, Ren-Hao; Zhang, Kun; Peng, Ru-Wen; Qi, Dong-Xiang

    2015-01-01

    In this work, we demonstrate that resonant full transmission of acoustic waves exists in subwavelength H-shaped metallic gratings, and transmission peaks can be efficiently tuned by adjusting the grating geometry. We investigate this phenomenon through both numerical simulations and theoretical calculations based on rigorous-coupled wave analysis. The transmission peaks are originated from Fabry-Perot resonances together with the couplings between the diffractive wave on the surface and the multiple guided modes in the slits. Moreover, the transmission modes can be efficiently tuned by adjusting the cavity geometry, without changing the grating thickness. The mechanism is analyzed based on an equivalent circuit model and verified by both the theoretical calculations and the numerical simulations. This research has potential application in acoustic-device miniaturization over a wide range of wavelengths

  15. Polarization Measurements on SUMI's TVLS Gratings

    Science.gov (United States)

    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.

  16. Polarization Measurements on SUMI's TVLS Gratings

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  18. Generation of sinusoidal fringes with a holographic phase grating and a phase-only spatial light modulator

    International Nuclear Information System (INIS)

    Berberova, Natalia; Stoykova, Elena; Sainov, Ventseslav

    2012-01-01

    A variety of pattern projection methods for the three-dimensional capture of objects is based on the generation of purely sinusoidal fringes. This is not an easy task, especially when a portable non-interferometric system for outdoor usage is required. The use of phase gratings with coherent illumination as a possible solution has the advantage of providing good stability and a large measurement volume. In this work, we analyze the quality of fringes projected with two sinusoidal phase gratings. The first grating is recorded on a silver-halide holographic plate by means of a Michelson interferometer. The spatial resolution of the silver-halide material used is greater than 6000 lines per millimeter, and the recorded grating is practically analogous to a smooth variation of the phase profile. The second grating is formed as a sinusoidal phase variation on a liquid crystal-on-silicon phase-only reflective display with a resolution of 1920×1080 pixels, a pixel pitch of 8 μm and 256 phase levels. The frequency content of the fringes projected with both gratings is analyzed and compared on the basis of the calculated Fresnel diffraction pattern, taking into account that the sinusoidal phase distribution in the case of a spatial light modulator is both sampled and quantized. Experimental fringe patterns projected using both gratings are also provided.

  19. Diffraction coherence in optics

    CERN Document Server

    Françon, M; Green, L L

    2013-01-01

    Diffraction: Coherence in Optics presents a detailed account of the course on Fraunhofer diffraction phenomena, studied at the Faculty of Science in Paris. The publication first elaborates on Huygens' principle and diffraction phenomena for a monochromatic point source and diffraction by an aperture of simple form. Discussions focus on diffraction at infinity and at a finite distance, simplified expressions for the field, calculation of the path difference, diffraction by a rectangular aperture, narrow slit, and circular aperture, and distribution of luminous flux in the airy spot. The book th

  20. WDM hybrid microoptical transceiver with Bragg volume grating

    Science.gov (United States)

    Jeřábek, Vitezslav; Armas, Julio; Mareš, David; Prajzler, Václav

    2012-02-01

    The paper presents the design, simulation and construction results of the wavelength division multiplex bidirectional transceiver module (WDM transceiver) for the passive optical network (PON) of a fiber to the home (FTTH) topology network. WDM transceiver uses a microoptical hybrid integration technology with volume holographic Bragg grating triplex filter -VHGT and a collimation lenses imagine system for wavelength multiplexing/ demultiplexing. This transmission type VHGT filter has high diffraction angle, very low insertion loses and optical crosstalk, which guide to very good technical parameters of transceiver module. WDM transceiver has been constructed using system of a four micromodules in the new circle topology. The optical micromodule with VHGT filter and collimation and decollimation lenses, two optoelectronics microwave receiver micromodules for receiving download information (internet and digital TV signals) and optoelectronic transmitter micromodule for transmitting upload information. In the paper is presented the optical analysis of the optical imagine system by ray-transfer matrix. We compute and measure VHGT characteristics such as diffraction angle, diffraction efficiency and diffraction crosstalk of the optical system for 1310, 1490 and 1550 nm wavelength radiation. For the design of optoelectronic receiver micromodule was used the low signal electrical equivalent circuit for the dynamic performance signal analysis. In the paper is presented the planar form WDM transceiver with polymer optical waveguides and two stage interference demultiplexing optical filter as well.

  1. Improved Phase-Mask Fabrication of Fiber Bragg Gratings

    Science.gov (United States)

    Grant, Joseph; Wang, Ying; Sharma, Anup

    2004-01-01

    An improved method of fabrication of Bragg gratings in optical fibers combines the best features of two prior methods: one that involves the use of a phase mask and one that involves interference between the two coherent laser beams. The improved method affords flexibility for tailoring Bragg wavelengths and bandwidths over wide ranges. A Bragg grating in an optical fiber is a periodic longitudinal variation in the index of refraction of the fiber core. The spatial period (Bragg wavelength) is chosen to obtain enhanced reflection of light of a given wavelength that would otherwise propagate relatively unimpeded along the core. Optionally, the spatial period of the index modulation can be made to vary gradually along the grating (such a grating is said to be chirped ) in order to obtain enhanced reflection across a wavelength band, the width of which is determined by the difference between the maximum and minimum Bragg wavelengths. In the present method as in both prior methods, a Bragg grating is formed by exposing an optical fiber to an ultraviolet-light interference field. The Bragg grating coincides with the pattern of exposure of the fiber core to ultraviolet light; in other words, the Bragg grating coincides with the interference fringes. Hence, the problem of tailoring the Bragg wavelength and bandwidth is largely one of tailoring the interference pattern and the placement of the fiber in the interference pattern. In the prior two-beam interferometric method, a single laser beam is split into two beams, which are subsequently recombined to produce an interference pattern at the location of an optical fiber. In the prior phase-mask method, a phase mask is used to diffract a laser beam mainly into two first orders, the interference between which creates the pattern to which an optical fiber is exposed. The prior two-beam interferometric method offers the advantage that the period of the interference pattern can be adjusted to produce gratings over a wide range

  2. Fiber Bragg Grating Based Thermometry.

    Science.gov (United States)

    Ahmed, Zeeshan; Filla, James; Guthrie, William; Quintavalle, John

    In recent years there has been considerable interest in developing photonic temperature sensors such as the Fiber Bragg gratings (FBG) as an alternative to resistance thermometry. In this study we examine the thermal response of FBGs over the temperature range of 233 K to 393 K. We demonstrate, in hermetically sealed dry Argon environment, FBG devices show a quadratic dependence on temperature with expanded uncertainties (k=2) of ≈500 mK. Our measurements indicate that the combined measurement uncertainty is dominated by uncertainty in determining peak center fitting and thermal ageing of polyimide coated fibers.

  3. Spatial filter with volume gratings for high-peak-power multistage laser amplifiers

    Science.gov (United States)

    Tan, Yi-zhou; Yang, Yi-sheng; Zheng, Guang-wei; Shen, Ben-jian; Pan, Heng-yue; Liu, Li

    2010-08-01

    The regular spatial filters comprised of lens and pinhole are essential component in high power laser systems, such as lasers for inertial confinement fusion, nonlinear optical technology and directed-energy weapon. On the other hand the pinhole is treated as a bottleneck of high power laser due to harmful plasma created by the focusing beam. In this paper we present a spatial filter based on angular selectivity of Bragg diffraction grating to avoid the harmful focusing effect in the traditional pinhole filter. A spatial filter consisted of volume phase gratings in two-pass amplifier cavity were reported. Two-dimensional filter was proposed by using single Pi-phase-shifted Bragg grating, numerical simulation results shown that its angular spectrum bandwidth can be less than 160urad. The angular selectivity of photo-thermorefractive glass and RUGATE film filters, construction stability, thermal stability and the effects of misalignments of gratings on the diffraction efficiencies under high-pulse-energy laser operating condition are discussed.

  4. Transmission line equivalent circuit model applied to a plasmonic grating nanosurface for light trapping.

    Science.gov (United States)

    Polemi, Alessia; Shuford, Kevin L

    2012-01-02

    In this paper, we show how light absorption in a plasmonic grating nanosurface can be calculated by means of a simple, analytical model based on a transmission line equivalent circuit. The nanosurface is a one-dimensional grating etched into a silver metal film covered by a silicon slab. The transmission line model is specified for both transverse electric and transverse magnetic polarizations of the incident light, and it incorporates the effect of the plasmonic modes diffracted by the ridges of the grating. Under the assumption that the adjacent ridges are weakly interacting in terms of diffracted waves, we show that the approximate, closed form expression for the reflection coefficient at the air-silicon interface can be used to evaluate light absorption of the solar cell. The weak-coupling assumption is valid if the grating structure is not closely packed and the excitation direction is close to normal incidence. Also, we show the utility of the circuit theory for understanding how the peaks in the absorption coefficient are related to the resonances of the equivalent transmission model and how this can help in designing more efficient structures.

  5. Measurement of grating visibility of a fiber Bragg grating based on bent-spectral analysis.

    Science.gov (United States)

    Gunawardena, Dinusha S; Lai, Man-Hong; Lim, Kok-Sing; Ali, Muhammad M; Ahmad, Harith

    2015-02-10

    In this study, a technique for measuring the grating visibility of the fiber Bragg grating (FBG) based on bent-spectral analysis is proposed. From varying ac and dc coupling coefficients at different bending radii, the grating visibility is estimated with the aid of a simple mathematical model. The investigation begins with the estimation of the grating visibility from the transmission spectra of the FBG during the inscription process. After that, the FBGs are subjected to a bending test with reducing radii, and again the transmission spectra are recorded. It is shown that the estimated grating visibility is in agreement with the result determined from the earlier inscription process.

  6. An improved method for separating the kinetics of anisotropic and topographic gratings in side-chain azobenzene polyesters

    DEFF Research Database (Denmark)

    Helgert, M.; Fleck, B.; Wenke, L.

    2000-01-01

    the polarization of the first-order diffracted beam. The main advantage of this method is that both parts can be determined simultaneously by only one measurement. Furthermore the displacement between both gratings can be determined in a similar manner. Experimental results obtained with two different polyesters...

  7. Phase behavior in diffraction

    International Nuclear Information System (INIS)

    Checon, A.

    1983-01-01

    Theoretical formulation of a straight edge diffraction shows a phase difference of π/2 between the incoming and diffracted waves. Experiments using two straight edges do not confirm the π/2 difference but suggest that the incoming wave is in phase with the wave diffracted into the shadowed region of the edge and out of phase by a factor of π with the wave diffracted into the illuminated region. (Author) [pt

  8. Theory of Coherent Radiation from a Grating-Waveguide Free-Electron Laser

    CERN Document Server

    Huang, Y C

    2005-01-01

    A Smith-Purcell radiator produces transversely asymmetric radiation modes due to the arrangement of a grating on one side of the electron beam. This asymmetric output could limit the usefulness of such a device in the THz spectrum where diffraction of waves is severe. It is possible to produce symmetric radiation from a double-grating waveguide driven by an electron beam traversing the waveguide gap. We derive a theory that describes the modes and small signal gain of this novel grating-waveguide free-electron laser. Our theory shows that extremely high laser gain is obtained when the electron beam is phase matched to the middle or edge of the radiation bands where the radiation modes have zero group velocity. In our calculation we obtained 66dB/mm gain at 298 µm for a 5 mA, 30keV driving beam in a grating waveguide with a 50-micron, 40% duty-cycle grating period, a 60-micron groove depth, and a 150 micron waveguide gap. This extremely high gain indicates that this novel device establishes resonance...

  9. Interacting binary stars

    CERN Document Server

    Sahade, Jorge; Ter Haar, D

    1978-01-01

    Interacting Binary Stars deals with the development, ideas, and problems in the study of interacting binary stars. The book consolidates the information that is scattered over many publications and papers and gives an account of important discoveries with relevant historical background. Chapters are devoted to the presentation and discussion of the different facets of the field, such as historical account of the development in the field of study of binary stars; the Roche equipotential surfaces; methods and techniques in space astronomy; and enumeration of binary star systems that are studied

  10. Binary Masking & Speech Intelligibility

    DEFF Research Database (Denmark)

    Boldt, Jesper

    The purpose of this thesis is to examine how binary masking can be used to increase intelligibility in situations where hearing impaired listeners have difficulties understanding what is being said. The major part of the experiments carried out in this thesis can be categorized as either experime......The purpose of this thesis is to examine how binary masking can be used to increase intelligibility in situations where hearing impaired listeners have difficulties understanding what is being said. The major part of the experiments carried out in this thesis can be categorized as either...... experiments under ideal conditions or as experiments under more realistic conditions useful for real-life applications such as hearing aids. In the experiments under ideal conditions, the previously defined ideal binary mask is evaluated using hearing impaired listeners, and a novel binary mask -- the target...... binary mask -- is introduced. The target binary mask shows the same substantial increase in intelligibility as the ideal binary mask and is proposed as a new reference for binary masking. In the category of real-life applications, two new methods are proposed: a method for estimation of the ideal binary...

  11. Overview on grating developments at ESA

    Science.gov (United States)

    Guldimann, B.; Deep, A.; Vink, R.; Harnisch, B.; Kraft, S.; Sierk, B.; Bazalgette, G.; Bézy, J.-L.

    2017-11-01

    In the frame of recent studies and missions, ESA has been performing various pre-developments of optical gratings for instruments operating at wavelengths from the UV up to the SWIR. The instrument requirements of Sentinel-4, Sentinel-5, CarbonSat and FLEX are driving the need for advanced designs and technologies leading to gratings with high efficiency, high spectral resolution, low stray light and low polarization sensitivities. Typical ESA instruments (e.g. Sciamachy, GOME, MERIS, OLCI, NIRSpec) were and are based on ruled gratings or gratings manufactured with one holographic photoresist mask layer which is transferred to an optical substrate (e.g. glass, glass ceramic) with dry etching methods and subsequently either coated with a reflective coating or used as a mold for replication. These manufacturing methods lead to blazed grating profiles with a metallic reflective surface. The vast majority of spectrometers on ground are still based on such gratings. In general, gratings based on grooved metallic surfaces tend for instance to polarize the incoming light significantly and are therefore not always suitable for ESA's needs of today. Gratings made for space therefore evolved to many other designs and concepts which will be reported in this paper.

  12. The Flexibility of Pusher Furnace Grate

    Directory of Open Access Journals (Sweden)

    Słowik J.A.

    2016-12-01

    Full Text Available The lifetime of guide grates in pusher furnaces for heat treatment could be increased by raising the flexibility of their structure through, for example, the replacement of straight ribs, parallel to the direction of grate movement, with more flexible segments. The deformability of grates with flexible segments arranged in two orientations, i.e. crosswise (perpendicular to the direction of compression and lengthwise (parallel to the direction of compression, was examined. The compression process was simulated using SolidWorks Simulation program. Relevant regression equations were also derived describing the dependence of force inducing the grate deformation by 0.25 mm ‒ modulus of grate elasticity ‒ on the number of flexible segments in established orientations. These calculations were made in Statistica and Scilab programs. It has been demonstrated that, with the same number of segments, the crosswise orientation of flexible segments increases the grate structure flexibility in a more efficient way than the lengthwise orientation. It has also been proved that a crucial effect on the grate flexibility has only the quantity and orientation of segments (crosswise / lengthwise, while the exact position of segments changes the grate flexibility by less than 1%.

  13. New generation DWDM fibre grating devices

    OpenAIRE

    Zervas, M.N.

    2000-01-01

    Using a recently developed inverse scattering layer-peeling algorithm and a modified stroboscopic grating writing technique, we have designed and successfully demonstrated novel grating devices, such as 50GHz-bandwidth dispersion compensators and square dispersionless filters, suitable for future high performance DWDM optical systems.

  14. High order Bragg grating microfluidic dye laser

    DEFF Research Database (Denmark)

    Balslev, Søren; Kristensen, Anders

    2004-01-01

    We demonstrate a single mode distributed feedback liquid dye laser, based on a short 133 'rd order Bragg grating defined in a single polymer layer between two glass substrates.......We demonstrate a single mode distributed feedback liquid dye laser, based on a short 133 'rd order Bragg grating defined in a single polymer layer between two glass substrates....

  15. Straw combustion on slow-moving grates

    DEFF Research Database (Denmark)

    Kær, Søren Knudsen

    2005-01-01

    Combustion of straw in grate-based boilers is often associated with high emission levels and relatively poor fuel burnout. A numerical grate combustion model was developed to assist in improving the combustion performance of these boilers. The model is based on a one-dimensional ‘‘walking...

  16. A MANUALLY OPERATED CASSAVA GRATING MACHINE

    African Journals Online (AJOL)

    Dr Obe

    1984-09-01

    Sep 1, 1984 ... substantial losses arising from the inability of the person to hold small pieces of cassava roots for grating. Happily, there now exist various. Versions of mechanical graters which are driven by electric motors or small internal combustion engines. In fact, it may be said that cassava grating has been effectively.

  17. Radical polymerization in holographic grating formation in PQ-PMMA photopolymer part II: Consecutive exposure and dark decay

    Science.gov (United States)

    Yu, Dan; Liu, Hongpeng; Geng, Yaohui; Wang, Weibo; Zhao, Yuanyuan

    2014-11-01

    Photochemical radical polymerization in phenathrenequinone doped poly(methyl methacrylate) photopolymer are investigated theoretically and experimentally under consecutive exposure. The detailed photochemical mechanisms are analyzed. Based on the rate equations of photochemical reactions, the diffusion models with nonlocal response are proposed to describe the kinetic process of radical polymerization and the significance of photochemical processes for the grating formation. In experiments, the temporal evolution of diffraction efficiency in grating formation is measured under consecutive exposure and after exposure. The percentages of these radical polymerizations, namely the polymerization of PQ with matrix, the bimolecular combination of MMA molecules, and the disproportionation of MMA molecules, are extracted quantitatively by comparing theory with experiments. It is indicated that the polymerization of PQ with matrix is primary photochemical process which dominated the grating formation under consecutive exposure. In this period, the contribution of chain polymerization of MMA radicals is weak for the grating formation. After reaching the peak values of grating strength, the influence of the free MMA molecules and photoproduct macromolecules on the grating decay is discussed in a long-term period. The diffusion coefficients of MMA and photoproduct are extracted by fitting the curves using double exponential function. MMA’s diffusion contributed to the fast decay process of grating after exposure and photoproduct’s diffusion contributed to the slow and long decay of grating. The results break previous understanding about the diffusion of single photoproduct macromolecules lead to the dark decay of grating. This investigation can provide a significant foundation for improving modulation depth and long-term stability by photochemical mechanism.

  18. High-resolution compact spectrometer based on a custom-printed varied-line-spacing concave blazed grating.

    Science.gov (United States)

    Chen, Jianwei; Chen, Wang; Zhang, Guodong; Lin, Hui; Chen, Shih-Chi

    2017-05-29

    We present the modeling, design and characterization of a compact spectrometer, achieving a resolution better than 1.5 nm throughout the visible spectrum (360-825 nm). The key component in the spectrometer is a custom-printed varied-line-space (VLS) concave blazed grating, where the groove density linearly decreases from the center of the grating (530 g/mm) at a rate of 0.58 nm/mm to the edge (528 g/mm). Parametric models have been established to deterministically link the system performance with the VLS grating design parameters, e.g., groove density, line-space varying rate, and to minimize the system footprint. Simulations have been performed in ZEMAX to confirm the results, indicating a 15% enhancement in system resolution versus common constant line-space (CLS) gratings. Next, the VLS concave blazed grating is fabricated via our vacuum nanoimprinting system, where a polydimethylsiloxane (PDMS) stamp is non-uniformly expanded to form the varied-line-spacing pattern from a planar commercial grating master (600 g/mm) for precision imprinting. The concave blazed grating is measured to have an absolute diffraction efficiency of 43%, higher than typical holographic gratings (~30%) used in the commercial compact spectrometers. The completed compact spectrometer contains only one optical component, i.e., the VLS concave grating, as well as an entrance slit and linear photodetector array, achieving a footprint of 11 × 11 × 3 cm 3 , which makes it the most compact and resolving (1.46 nm) spectrometer of its kind.

  19. Nanofabrication and characterization of high-line-density x-ray transmission gratings

    DEFF Research Database (Denmark)

    Zhu, Xiaoli; Li, Hailiang; Cao, Leifeng

    2017-01-01

    We report the nanofabrication and characterization of x-ray transmission gratings with a high aspect ratio and a feature size of down to 65 nm. Two nanofabrication methods, the combination of electron beam and optical lithography and the combination of electron beam, x-ray, and optical lithograph...... the development of x-ray diffractive optical elements. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)...

  20. Binary effectivity rules

    DEFF Research Database (Denmark)

    Keiding, Hans; Peleg, Bezalel

    2006-01-01

    effectivity rule is regular if it is the effectivity rule of some regular binary SCR. We characterize completely the family of regular binary effectivity rules. Quite surprisingly, intrinsically defined von Neumann-Morgenstern solutions play an important role in this characterization...

  1. Binary colloidal crystals

    NARCIS (Netherlands)

    Christova-Zdravkova, C.G.

    2005-01-01

    Binary crystals are crystals composed of two types of particles having different properties like size, mass density, charge etc. In this thesis several new approaches to make binary crystals of colloidal particles that differ in size, material and charge are reported We found a variety of crystal

  2. The Generation of Higher Order Diffraction Beams by Photorefractive Record of Harmonic Optical Field

    Directory of Open Access Journals (Sweden)

    Norbert Tarjanyi

    2004-01-01

    Full Text Available There are some results of investigation of photorefractive record of interference field created by two planar wave of Ar laser (488 nm in LiNbO3:Fe presented in this work. Such record behaves as a phase diffraction grating. The time dependence of diffracted beam intensity informs about process of the record creation. To read this record a weak beam of He-Ne laser (632.8 nm was used. During recording and erasure process of the record, the intensities of the zero and intensities of higher orders on both sides of reading beam were detected. Experimentally obtained time dependences of intensities of diffracted beams were compared with dependences following from diffraction integral integral for harmonic phase grating. Quite small differences between measured and calculated dependences occurred. The differences show that there are some non-linear processes taking place at the record creation.

  3. Influence of 4,4’-azobis (4-cyanopentanoic acid in Transmission and Reflection Gratings Stored in a PVA/AA Photopolymer

    Directory of Open Access Journals (Sweden)

    Elena Fernandez

    2016-03-01

    Full Text Available Holographic transmission gratings with a spatial frequency of 2658 lines/mm and reflection gratings with a spatial frequency of 4553 lines/mm were stored in a polyvinyl alcohol (PVA/acrylamide (AA based photopolymer. This material can reach diffraction efficiencies close to 100% for spatial frequencies about 1000 lines/mm. However, for higher spatial frequencies, the diffraction efficiency decreases considerably as the spatial frequency increases. To enhance the material response at high spatial frequencies, a chain transfer agent, the 4,4’-azobis (4-cyanopentanoic acid, ACPA, is added to the composition of the material. Different concentrations of ACPA are incorporated into the main composition of the photopolymer to find the concentration value that provides the highest diffraction efficiency. Moreover, the refractive index modulation and the optical thickness of the transmission and reflection gratings were obtained, evaluated and compared to procure more information about the influence of the ACPA on them.

  4. Fast switchable ferroelectric liquid crystal gratings with two electro-optical modes

    International Nuclear Information System (INIS)

    Ma, Ying; Srivastava, A. K.; Chigrinov, V. G.; Kwok, H.-S.; Wang, Xiaoqian

    2016-01-01

    In this article, we reveal a theoretical and experimental illustration of the Ferroelectric liquid crystal (FLC) grating fabricated by mean of patterned alignment based on photo-alignment. The complexity related to the mismatching of the predefined alignment domains on the top and bottom substrate has been avoided by incorporating only one side photo aligned substrate while the other substrate does not have any alignment layer. Depending on the easy axis in the said alignment domains and the azimuth plane of the impinging polarized light, the diffracting element can be tuned in two modes i.e. DIFF/OFF switchable and DIFF/TRANS switchable modes, which can be applied to different applications. The diffraction profile has been illustrated theoretically that fits well with the experimental finding and thus the proposed diffraction elements with fast response time and high diffraction efficiency could find application in many modern devices.

  5. Novel High-Speed Photopolarimeter Based on a Metallic Grating

    International Nuclear Information System (INIS)

    Du, X L; Dai, J M; Sun, X G

    2006-01-01

    A novel high-speed photopolarimeter is presented in this paper, which is composed by the optical system, electronics system and PC. This instrument uses a metallic grating that can produce both reflective diffraction and transmission diffraction as a beam splitter to divide the incident light into many components, and the light fluxes of the four 1st order diffracted beams are converted linearly into four electrical signals by four photodiodes. After going through a signal conditioning circuit, these electrical signals are converted into digital values by high-speed A/D converters that can implement synchronous multi-channels sampling, and then the data sampled are high-speedily transmitted into the PC via a USB2.0 interface. The electrical signal vector I composed by the four electrical signals possesses the linear relationship with the incident light Stokes vector S. The nonsingular instrument matrix A of this instrument can be obtained by the calibration, and then the unknown Stokes vector S of the incidence light can be obtained from the equation S = A -1 I. The testing results show that the mean deviations of the measured Stokes parameters compared with the predicted values are less than 1% at 632.8nm. It is compact and easy to be installed, and can be used as a polarization state detector in real-time polarimetry and ellipsometry

  6. Mechanical polishing to improve uniformity of beam sampling grating and its effects on laser-induced damage

    Science.gov (United States)

    Rao, Huanle; Liu, Zhengkun; Liu, Ying; Fu, Shaojun

    2012-01-01

    As an important optical element, beam sampling grating (BSG) is used in the terminal of inertial confinement fusion (ICF) drivers. It can provide a very slight sampling beam for the precision diagnosing of laser energy and wavefront distortion. However, in practice, its non-uniform diffraction efficiency seriously influences the accurate signal of sampling beam, and finally affects diagnostic ability. BSG is usually fabricated by holographic ion beam etched (HIBE) process. In this paper, a mechanical polishing processing technology was used to improve uniformity of the diffraction efficiency of BSG after HIBE. In the processing, cerium oxide (CeO2) was used to polish the local areas of grating where exhibit higher diffraction efficiency with the purpose of changing the depth of grating profile, and then they have similar efficiency with the surrounding areas. By iteration of the above process, BSG finally achieve the improved uniformity of diffraction efficiency over the area of a 430 x 430 mm2. The RMS of diffraction efficiency of BSG after mechanical polishing shows great reduction down to 4.8% as compared with that of the as-polished RMS of 21%. The effects of this processing on laser damage was characterized by the measuring the LIDT for the laser radiations of 355nm.

  7. The differential method for grating efficiencies implemented in mathematica

    Energy Technology Data Exchange (ETDEWEB)

    Valdes, V.; McKinney, W. [Lawrence Berkeley Lab., CA (United States); Palmer, C. [Milton Co., Rochester, NY (United States). Roy Analytical Products Div.

    1993-08-01

    In order to facilitate the accurate calculation of diffraction grating efficiencies in the soft x-ray region, we have implemented the differential method of Neviere and Vincent in Mathematica [1]. This simplifies the programming to maximize the transparency of the theory for the user. We alleviate some of the overhead burden of the Mathematica program by coding the time-consuming numerical integration in C subprograms. We recall the differential method directly from Maxwell`s equations. The pseudo-periodicity of the grating profile and the electromagnetic fields allows us to use their Fourier series expansions to formulate an infinite set of coupled differential equations. A finite subset of the equations are then numerically integrated using the Numerov method for the transverse electric (TE) case and a fourth-order Runge-Kutta algorithm for the transverse magnetic (TM) case. We have tested our program by comparisons with the scalar theory and with published theoretical results for the blazed, sinusoidal and square wave profiles. The Reciprocity Theorem has also been used as a means to verify the method. We have found it to be verified for several cases to within the computational accuracy of the method.

  8. Research on long-range grating interferometry with nanometer resolution

    International Nuclear Information System (INIS)

    Chu, Xingchun; Zhao, Shanghong; Lü, Haibao

    2008-01-01

    Grating interferometry that features long range and nanometer resolution is presented. The optical system was established based on a single long metrology grating. The large fringe multiplication was achieved by properly selecting two high-order diffraction beams to form a fringe pattern. The fringe pattern collected by a linear array was first tailored to a few multiples of fringes in order to suppress the effect of the energy leakage on phase-extracting precision when the fast Fourier transform (FFT) algorithm was used to calculate its phase. Thus, the phase-extracting precision of a tailored fringe pattern by FFT was greatly improved. Based on this, a novel subdividing method, which exploited the time-shift property of FFT, was developed to subdivide the fringe with large multiple and high accuracy. Numerical results show that the system resolution reaches 1 nm. The experimental results obtained against a capacitive sensor in the sub-mm range show that the measurement precision of the system is less than 10 nm. (technical design note)

  9. Access Platforms for Offshore Wind Turbines Using Gratings

    DEFF Research Database (Denmark)

    Andersen, Thomas Lykke; Rasmussen, Michael R.

    2008-01-01

    The paper deals with forces generated by a stationary jet on different types of gratings and a solid plate. The force reduction factors for the different gratings compared to the solid plate mainly depend on the porosity of the gratings, but the geometry of the grating is also of some importance....

  10. The infrared imaging spectrograph (IRIS) for TMT: volume phase holographic grating performance testing and discussion

    Science.gov (United States)

    Chen, Shaojie; Meyer, Elliot; Wright, Shelley A.; Moore, Anna M.; Larkin, James E.; Maire, Jerome; Mieda, Etsuko; Simard, Luc

    2014-07-01

    Maximizing the grating efficiency is a key goal for the first light instrument IRIS (Infrared Imaging Spectrograph) currently being designed to sample the diffraction limit of the TMT (Thirty Meter Telescope). Volume Phase Holographic (VPH) gratings have been shown to offer extremely high efficiencies that approach 100% for high line frequencies (i.e., 600 to 6000l/mm), which has been applicable for astronomical optical spectrographs. However, VPH gratings have been less exploited in the near-infrared, particularly for gratings that have lower line frequencies. Given their potential to offer high throughputs and low scattered light, VPH gratings are being explored for IRIS as a potential dispersing element in the spectrograph. Our team has procured near-infrared gratings from two separate vendors. We have two gratings with the specifications needed for IRIS current design: 1.51-1.82μm (H-band) to produce a spectral resolution of 4000 and 1.19-1.37μm (J-band) to produce a spectral resolution of 8000. The center wavelengths for each grating are 1.629μm and 1.27μm, and the groove densities are 177l/mm and 440l/mm for H-band R=4000 and J-band R=8000, respectively. We directly measure the efficiencies in the lab and find that the peak efficiencies of these two types of gratings are quite good with a peak efficiency of ~88% at the Bragg angle in both TM and TE modes at H-band, and 90.23% in TM mode, 79.91% in TE mode at J-band for the best vendor. We determine the drop in efficiency off the Bragg angle, with a 20-23% decrease in efficiency at H-band when 2.5° deviation from the Bragg angle, and 25%-28% decrease at J-band when 5° deviation from the Bragg angle.

  11. Nanoscale freestanding gratings for ultraviolet blocking filters

    Energy Technology Data Exchange (ETDEWEB)

    van Beek, J.T.; Fleming, R.C.; Hindle, P.S.; Prentiss, J.D.; Schattenburg, M.L. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Ritzau, S. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    1998-11-01

    Ultraviolet (UV) blocking filters are needed for atomic flux imaging in environments where high levels of ultraviolet radiation are present. Freestanding gratings are a promising candidate for UV filtering. They have a high aspect ratio ({approximately}13), narrow ({approximately}40 nm) slots, and effectively block UV radiation. The grating fabrication process makes use of several etching, electroplating, and lithographic steps and includes an optional step to plug pinholes induced by particles during processing. Gratings were successfully manufactured and tested. Measured UV transmissions of {approximately}10{sup {minus}5} and particle transmissions of {approximately}10{percent} are in agreement with theoretical predictions. {copyright} {ital 1998 American Vacuum Society.}

  12. Optical Fiber Grating Hydrogen Sensors: A Review.

    Science.gov (United States)

    Dai, Jixiang; Zhu, Li; Wang, Gaopeng; Xiang, Feng; Qin, Yuhuan; Wang, Min; Yang, Minghong

    2017-03-12

    In terms of hydrogen sensing and detection, optical fiber hydrogen sensors have been a research issue due to their intrinsic safety and good anti-electromagnetic interference. Among these sensors, hydrogen sensors consisting of fiber grating coated with sensitive materials have attracted intensive research interests due to their good reliability and distributed measurements. This review paper mainly focuses on optical fiber hydrogen sensors associated with fiber gratings and various materials. Their configurations and sensing performances proposed by different groups worldwide are reviewed, compared and discussed in this paper. Meanwhile, the challenges for fiber grating hydrogen sensors are also addressed.

  13. Fiber Bragg Grating Sensors for Harsh Environments

    Directory of Open Access Journals (Sweden)

    Stephen J. Mihailov

    2012-02-01

    Full Text Available 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.

  14. Speed enhancement in VCSELs employing grating mirrors

    DEFF Research Database (Denmark)

    Chung, Il-Sug; Mørk, Jesper

    2013-01-01

    In recent years, various approaches to improve the speed of directly modulated vertical-cavity surface-emitting lasers (VCSELs) have been reported and demonstrated good improvement. In this paper, we propose and numerically investigate a new possibility of using high-index-contrast grating (HCG......) as mirror for VCSELs. By changing the grating design, one can control the reflection delay of the grating mirror, enabling the control of cavity photon lifetime. On the other hand, short energy penetration depth of the HCG results in smaller modal volume, compared to DBR VCSELs. An example structure shows...... that the HCG VCSEL has a 30-% higher 3-dB bandwidth than the DBR VCSEL....

  15. Thermal annealing of tilted fiber Bragg gratings

    Science.gov (United States)

    González-Vila, Á.; Rodríguez-Cobo, L.; Mégret, P.; Caucheteur, C.; López-Higuera, J. M.

    2016-05-01

    We report a practical study of the thermal decay of cladding mode resonances in tilted fiber Bragg gratings, establishing an analogy with the "power law" evolution previously observed on uniform gratings. We examine how this process contributes to a great thermal stability, even improving it by means of a second cycle slightly increasing the annealing temperature. In addition, we show an improvement of the grating spectrum after annealing, with respect to the one just after inscription, which suggests the application of this method to be employed to improve saturation issues during the photo-inscription process.

  16. Gratings with Blaze Angles Down to 0.1° for Photon Energies up to 10 keV

    Science.gov (United States)

    Heidemann, K. F.; Nelles, B.; Lenke, R.

    2007-01-01

    A new technique for the patterning of blazed gratings with extremely small blaze angles down to 0.1° is described. Mechanically ruled gratings are transferred from the gold ruling layer into the silicon substrate by reactive ionbeam etching. The primarily ruled blaze angle can be reduced by a factor of up to 28. The plane blaze facets are maintained during the etching process resulting in high blaze efficiency. The rms micro roughness on the blaze facets, that affects the efficiency as well as the diffuse straylight is reduced to below 0.2 nm by this technique. Groove profiles of such gratings with various groove densities and blaze angles measured by atomic force microscopy are presented. Calculated diffraction efficiency and resolving power and the impact of grating imperfections on the monochromator and spectrometer design are discussed [1] and [2]. Plane blazed gratings patterned by this technique were delivered to BESSY and to Sincrotrone Trieste. The results of efficiency measurements of these gratings are reported in [3] and [4].

  17. Biomimetic spiral grating for stable and highly efficient absorption in crystalline silicon thin-film solar cells

    KAUST Repository

    Hou, Jin

    2017-09-12

    By emulating the phyllotaxis structure of natural plants, which has an efficient and stable light capture capability, a two-dimensional spiral grating is introduced on the surface of crystalline silicon solar cells to obtain both efficient and stable light absorption. Using the rigorous coupled wave analysis method, the absorption performance on structural parameter variations of spiral gratings is investigated firstly. Owing to diffraction resonance and excellent superficies antireflection, the integrated absorption of the optimal spiral grating cell is raised by about 77 percent compared with the conventional slab cell. Moreover, though a 15 percent deviation of structural parameters from the optimal spiral grating is applied, only a 5 percent decrease of the absorption is observed. This reveals that the performance of the proposed grating would tolerate large structural variations. Furthermore, the angular and polarization dependence on the absorption of the optimized cell is studied. For average polarizations, a small decrease of only 11 percent from the maximum absorption is observed within an incident angle ranging from −70 to 70 degrees. The results show promising application potentials of the biomimetic spiral grating in the solar cell.

  18. Neutron powder diffraction

    International Nuclear Information System (INIS)

    David, W.I.F.

    1990-01-01

    Neutron powder diffraction is a powerful technique that provides a detailed description of moderately complex crystal structures. This is nowhere more apparent than in the area of high temperature superconductors where neutron powder diffraction has provided precise structural and magnetic information, not only under ambient conditions but also at high and low temperatures and high pressures. Outside superconductor research, the variety of materials studied by neutron powder diffraction is equally impressive including zeolites, fast ionic conductors, permanent magnets and materials undergoing phase transitions. Recent advances that include high resolution studies and real-time crystallography are presented. Future possibilities of neutron powder diffraction are discussed

  19. Phase retrieval for superposed signals from multiple binary objects

    DEFF Research Database (Denmark)

    Alpers, Andreas; Herman, Gabor T.; Poulsen, Henning Friis

    2010-01-01

    We introduce the binary superposed phase retrieval problem that aims at reconstructing multiple 0/1-valued functions with nonoverlapping bounded supports from moduli of superpositions of several displaced copies of their individual Fourier transforms. We discuss an application in coherent diffrac...... diffraction imaging of crystalline objects, propose two algorithms, and evaluate their performance by means of simulations. © 2010 Optical Society of America...

  20. Adsorption of hexavalent chromium by graphite–chitosan binary ...

    Indian Academy of Sciences (India)

    Graphite chitosan binary (GCB) composite was prepared for hexavalent chromium adsorption from studied water. GCB was characterized by TGA, FTIR, SEM and X-ray diffraction techniques.Wide porous sorptive surface of 3.89 m 2 g − 1 and absorptive functionalities of GCB was due to 20% (w/w) graphite support on ...

  1. Adsorption of hexavalent chromium by graphite–chitosan binary

    Indian Academy of Sciences (India)

    Graphite chitosan binary (GCB) composite was prepared for hexavalent chromium adsorption from studied water. GCB was characterized by TGA, FTIR, SEM and X-ray diffraction techniques.Wide porous sorptive surface of 3.89 m 2 g − 1 and absorptive functionalities of GCB was due to 20% (w/w) graphite support on ...

  2. An Improved Method for Separating the Kinetics of the Induction of Anisotropic and Topographic Gratings in Side-Chain Azobenzene Polyesters

    DEFF Research Database (Denmark)

    Helgert, M.; Fleck, B.; Wenke, L.

    2000-01-01

    The induction of anisotropy gratings in side-chain azobenzene polyesters is accompanied by the formation of surface relief. We introduce an improved holographic method to separate the contributions of the anisotropic and the topographic part to the diffraction efficiency by analyzing the polariza......The induction of anisotropy gratings in side-chain azobenzene polyesters is accompanied by the formation of surface relief. We introduce an improved holographic method to separate the contributions of the anisotropic and the topographic part to the diffraction efficiency by analyzing...

  3. Evidence of a stable binary CdCa quasicrystalline phase

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Jensen, C.H.; Rasmussen, A.R.

    2001-01-01

    Quasicrystals with a primitive icosahedral structure and a quasilattice constant of 5.1215 Angstrom have been synthesized in a binary Cd-Ca system. The thermal stability of the quasicrystal has been investigated by in situ high-temperature x-ray powder diffraction using synchrotron radiation. It ....... It is demonstrated that the binary CdCa quasicrystal is thermodynamic stable up to its melting temperature. The linear thermal expansion coefficient of the quasicrystal is 2.765x10(-5) K-1. (C) 2001 American Institute of Physics.......Quasicrystals with a primitive icosahedral structure and a quasilattice constant of 5.1215 Angstrom have been synthesized in a binary Cd-Ca system. The thermal stability of the quasicrystal has been investigated by in situ high-temperature x-ray powder diffraction using synchrotron radiation...

  4. Liquid crystal on subwavelength metal gratings

    Energy Technology Data Exchange (ETDEWEB)

    Palto, S. P.; Barnik, M. I.; Artemov, V. V.; Shtykov, N. M.; Geivandov, A. R.; Yudin, S. G.; Gorkunov, M. V. [Shubnikov Institute of Crystallography of Russian Academy of Sciences, Leninsky pr. 59, 119333 Moscow (Russian Federation)

    2015-06-14

    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.

  5. BINARY MINOR PLANETS

    Data.gov (United States)

    National Aeronautics and Space Administration — The data set lists orbital and physical properties for well-observed or suspected binary/multiple minor planets including the Pluto system, compiled from the...

  6. Close binary stars

    International Nuclear Information System (INIS)

    Larsson-Leander, G.

    1979-01-01

    Studies of close binary stars are being persued more vigorously than ever, with about 3000 research papers and notes pertaining to the field being published during the triennium 1976-1978. Many major advances and spectacular discoveries were made, mostly due to increased observational efficiency and precision, especially in the X-ray, radio, and ultraviolet domains. Progress reports are presented in the following areas: observational techniques, methods of analyzing light curves, observational data, physical data, structure and models of close binaries, statistical investigations, and origin and evolution of close binaries. Reports from the Coordinates Programs Committee, the Committee for Extra-Terrestrial Observations and the Working Group on RS CVn binaries are included. (Auth./C.F.)

  7. Optical temperature sensor and thermal expansion measurement using a femtosecond micromachined grating in 6H-SiC.

    Science.gov (United States)

    DesAutels, G Logan; Powers, Peter; Brewer, Chris; Walker, Mark; Burky, Mark; Anderson, Gregg

    2008-07-20

    An optical temperature sensor was created using a femtosecond micromachined diffraction grating inside transparent bulk 6H-SiC, and to the best of our knowledge, this is a novel technique of measuring temperature. Other methods of measuring temperature using fiber Bragg gratings have been devised by other groups such as Zhang and Kahrizi [in MEMS, NANO, and Smart Systems (IEEE, 2005)]. This temperature sensor was, to the best of our knowledge, also used for a novel method of measuring the linear and nonlinear coefficients of the thermal expansion of transparent and nontransparent materials by means of the grating first-order diffracted beam. Furthermore the coefficient of thermal expansion of 6H-SiC was measured using this new technique. A He-Ne laser beam was used with the SiC grating to produce a first-order diffracted beam where the change in deflection height was measured as a function of temperature. The grating was micromachined with a 20 microm spacing and has dimensions of approximately 500 microm x 500 microm (l x w) and is roughly 0.5 microm deep into the 6H-SiC bulk. A minimum temperature of 26.7 degrees C and a maximum temperature of 399 degrees C were measured, which gives a DeltaT of 372.3 degrees C. The sensitivity of the technique is DeltaT=5 degrees C. A maximum deflection angle of 1.81 degrees was measured in the first-order diffracted beam. The trend of the deflection with increasing temperature is a nonlinear polynomial of the second-order. This optical SiC thermal sensor has many high-temperature electronic applications such as aircraft turbine and gas tank monitoring for commercial and military applications.

  8. Diffractive optical elements written by photodeposition

    Energy Technology Data Exchange (ETDEWEB)

    Baal-Zedaka, I.; Hava, S.; Mirchin, N.; Margolin, R.; Zagon, M.; Lapsker, I.; Azoulay, J.; Peled, A

    2003-03-15

    In this work direct laser writing of diffractive optical elements (DOE) by photodeposition (PD) of amorphous selenium (a-Se) from colloid solutions has been investigated. We used a computer controlled laser scanner for patterning thin film micro-profiles creating thus planar optical elements by direct beam writing on surfaces immersed in a liquid phase PD cell. The laser employed was an argon ion laser at 488 nm wavelength, with powers up to 55 mW, for writing typically 25-250 {mu}m wide lines of 200 nm thickness at rates of about 150 {mu}m/s. Various elements made of photodeposited thin films on polymethyl-methacrylate (PMMA) substrates were produced for prototyping microlenses, linear grating arrays, cylindrical and circular profiled DOE patterns.

  9. Binary and ternary systems

    International Nuclear Information System (INIS)

    Petrov, D.A.

    1986-01-01

    Conditions for thermodynamical equilibrium in binary and ternary systems are considered. Main types of binary and ternary system phase diagrams are sequently constructed on the basis of general regularities on the character of transition from one equilibria to others. New statements on equilibrium line direction in the diagram triple points and their isothermal cross sections are developed. New represenations on equilibria in case of monovariant curve minimum and maximum on three-phase equilibrium formation in ternary system are introduced

  10. Binary and Millisecond Pulsars

    OpenAIRE

    Lorimer, D. R.

    2005-01-01

    We review the main properties, demographics and applications of binary and millisecond radio pulsars. Our knowledge of these exciting objects has greatly increased in recent years, mainly due to successful surveys which have brought the known pulsar population to over 1800. There are now 83 binary and millisecond pulsars associated with the disk of our Galaxy, and a further 140 pulsars in 26 of the Galactic globular clusters. Recent highlights include the discovery of the young relativistic b...

  11. Deuteron diffractive dissociation

    International Nuclear Information System (INIS)

    Antunes, A.C.B.; Caruso, F.

    1984-01-01

    Deuteron diffractive dissociation is studied in the framework of the Three Components Deck Model. The applicability of this model to light nuclei diffractive dissociation is assumed. The existence of a slope-mass-cos theta correlation is pointed out. The relevant distributions are obtained. (Author) [pt

  12. Astrophysics of white dwarf binaries

    NARCIS (Netherlands)

    Nelemans, G.A.

    2006-01-01

    White dwarf binaries are the most common compact binaries in the Universe and are especially important for low-frequency gravitational wave detectors such as LISA. There are a number of open questions about binary evolution and the Galactic population of white dwarf binaries that can be solved using

  13. Evolution of cataclysmic binaries

    International Nuclear Information System (INIS)

    Paczynski, B.

    1981-01-01

    Cataclysmic binaries with short orbital periods have low mass secondary components. Their nuclear time scale is too long to be of evolutionary significance. Angular momentum loss from the binary drives the mass transfer between the two components. As long as the characteristic time scale is compared with the Kelvin-Helmholtz time scale of the mass losing secondary the star remains close to the main sequence, and the binary period decreases with time. If angular momentum loss is due to gravitational radiation then the mass transfer time scale becomes comparable to the Kelvin-Helmoltz time scale when the secondary's mass decreases to 0.12 Msub(sun), and the binary period is reduced to 80 minutes. Later, the mass losing secondary departs from the main sequence and gradually becomes degenerate. Now the orbital period increases with time. The observed lower limit to the orbital periods of hydrogen rich cataclysmic binaries implies that gravitational radiation is the main driving force for the evolution of those systems. It is shown that binaries emerging from a common envelope phase of evolution are well detached. They have to lose additional angular momentum to become semidetached cataclysmic variables. (author)

  14. Structural stability of binary CdCa quasicrystal under high pressure

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Gerward, Leif; Olsen, J. S.

    2001-01-01

    The structural stability of a binary CdCa quasicrystal with a primitive icosahedral structure has been investigated by in situ high-pressure x-ray powder diffraction at an ambient temperature using synchrotron radiation. It is demonstrated that the icosahedral quasicrystalline structure of the sa......The structural stability of a binary CdCa quasicrystal with a primitive icosahedral structure has been investigated by in situ high-pressure x-ray powder diffraction at an ambient temperature using synchrotron radiation. It is demonstrated that the icosahedral quasicrystalline structure...... elasticity in the stable binary icosahedral CdCa quasicrystals....

  15. Design and fabrication of directional diffractive device on glass substrate for multiview holographic 3D display

    Science.gov (United States)

    Su, Yanfeng; Cai, Zhijian; Liu, Quan; Zou, Wenlong; Guo, Peiliang; Wu, Jianhong

    2018-01-01

    Multiview holographic 3D display based on the nano-grating patterned directional diffractive device can provide 3D images with high resolution and wide viewing angle, which has attracted considerable attention. However, the current directional diffractive device fabricated on the photoresist is vulnerable to damage, which will lead to the short service life of the device. In this paper, we propose a directional diffractive device on glass substrate to increase its service life. In the design process, the period and the orientation of the nano-grating at each pixel are carefully calculated accordingly by the predefined position of the viewing zone, and the groove parameters are designed by analyzing the diffraction efficiency of the nano-grating pixel on glass substrate. In the experiment, a 4-view photoresist directional diffractive device with a full coverage of pixelated nano-grating arrays is efficiently fabricated by using an ultraviolet continuously variable spatial frequency lithography system, and then the nano-grating patterns on the photoresist are transferred to the glass substrate by combining the ion beam etching and the reactive ion beam etching for controlling the groove parameters precisely. The properties of the etched glass device are measured under the illumination of a collimated laser beam with a wavelength of 532nm. The experimental results demonstrate that the light utilization efficiency is improved and optimized in comparison with the photoresist device. Furthermore, the fabricated device on glass substrate is easier to be replicated and of better durability and practicability, which shows great potential in the commercial applications of 3D display terminal.

  16. Focused-ion beam patterning of organolead trihalide perovskite for subwavelength grating nanophotonic applications

    KAUST Repository

    Alias, Mohd Sharizal

    2015-07-30

    The coherent amplified spontaneous emission and high photoluminescence quantum efficiency of organolead trihalide perovskite have led to research interest in this material for use in photonic devices. In this paper, the authors present a focused-ion beam patterning strategy for methylammonium lead tribromide (MAPbBr3) perovskite crystal for subwavelength grating nanophotonic applications. The essential parameters for milling, such as the number of scan passes, dwell time, ion dose, ion current, ion incident angle, and gas-assisted etching, were experimentally evaluated to determine the sputtering yield of the perovskite. Based on our patterning conditions, the authors observed that the sputtering yield ranged from 0.0302 to 0.0719 μm3/pC for the MAPbBr3 perovskite crystal. Using XeF2 for the focused-ion beam gas-assisted etching, the authors determined that the etching rate was reduced to between 0.40 and 0.97, depending on the ion dose, compared with milling with ions only. Using the optimized patterning parameters, the authors patterned binary and circular subwavelength grating reflectors on the MAPbBr3 perovskite crystal using the focused-ion beam technique. Based on the computed grating structure with around 97% reflectivity, all of the grating dimensions (period, duty cycle, and grating thickness) were patterned with nanoscale precision (>±3 nm), high contrast, and excellent uniformity. Our results provide a platform for utilizing the focused-ion beam technique for fast prototyping of photonic nanostructures or nanodevices on organolead trihalide perovskite.

  17. High-accuracy alignment of the grating pattern along silicon directions using a short rectangular array

    Science.gov (United States)

    Wang, Yu; Liu, Zhengkun; Zheng, Yanchang; Qiu, Keqiang; Hong, Yilin

    2017-06-01

    A method for the accurate alignment of the grating pattern along silicon directions is developed. A short rectangular array is fabricated as an alignment pattern in silicon wafer through quick pre-anisotropic wet etching. The short rectangles can locate the {1 1 1} planes with zero error without the need to determine the crystal directions manually. The grating pattern is aligned along directions by using the diffraction characteristic of the short rectangular array without a superfluous process or equipment. The alignment pattern occupies an area of less than 4 mm2 and can be fabricated through one-time wet etching in any location on the silicon wafer. The alignment error of this method is up to +/- 0.013°. The method is used to fabricate a silicon grating with a period of 220 nm and a groove depth of 1.8 µm. The sidewalls of the grating are atomically smooth {1 1 1} planes with an RMS roughness of 0.162 nm.

  18. Development of a Novel Breast Cancer Detector based on Improved Holography Concave Grating Imaging Spectrometer

    International Nuclear Information System (INIS)

    Ren Zhong; Liu Guodong; Zeng Lvming; Huang Zhen

    2011-01-01

    Breast cancer can be detected by B-mode ultrasonic imaging, X-mammography, CT imaging, and MRI. But some drawbacks existed in these methods, their applications was limited in some certain. So, a novel high resolution breast cancer detector (BCD) is developed in this paper. Meanwhile, an improved holography concave grating imaging spectrometer (HCGIS) is designed. In this HCGIS, the holography concave grating is used as the diffraction grating. Additionally, CCD with combined image acquisition (IAQ) card and the 3D scan platform are used as the spectral image acquisition component. This BCD consists of the light source unit, light-path unit, check cavity, splitting-light unit, spectrum acquisition and imaging unit, signal processing unit, computer and data analysis software unit, etc. Experimental results show that the spectral range of the novel BCD can reach 300-1000 nm, its wavelength resolution can reach 1nm, and this system uses the back-split-light technology and the splitting-light structure of holography concave grating. Compared with the other instruments of breast cancer detection, this BCD has many advantages, such as, compacter volume, simpler algorithm, faster processing speed, higher accuracy, cheaper cost and higher resolution, etc. Therefore, this BCD will have the potential values in the detection of breast disease.

  19. POINT-BY-POINT INSCRIPTION OF FIBER BRAGG GRATINGS INTO BIREFRINGENT OPTICAL FIBER THROUGH PROTECTIVE ACRYLATE COATING BY TI:SA FEMTOSECOND LASER

    Directory of Open Access Journals (Sweden)

    S. V. Arkhipov,

    2016-05-01

    Full Text Available The paper deals withpoint-by-point inscriptionof fiber Bragg gratings by the 800 nm Ti:Sa femtosecond laser pulses into a unique birefringent fiber with elliptical stress cladding of home manufacture. The proposed inscriptionmethod has advantages over the conventional phase mask method. The possibility to create complex grating structures and relatively high transparency of acrylate coating to the Ti:Sa femtosecond laser radiation of 800 nm gives the possibility for inscriptionof phase shifting gratings, chirped grating and superstructures without stripping the fiber. Also, this method makes it possible to inscribethese diffractive structures with and without co-doping of GeO2 in the fiber core. Achieved reflectance was 10%. The microscopic image of the diffractive structure in the fiber core is presented. The grating of 1.07 µm is realized by pulling the fiber with constant speed while the laser pulses are applied with a repetition frequency of 1 kHz. The results are usable in the sphere of creation of different fiber optic sensitive elements based on Bragg gratings.

  20. Binary magnetic structures in HoEr

    DEFF Research Database (Denmark)

    Howard, B.K.; Bohr, J.

    1991-01-01

    The magnetic structure of a single crystal of the rare earth random alloy Ho50% Er50% has been investigated by elastic neutron diffraction measurements in the temperature range 120-10 K. Three distinct magnetic phases are identified below the Neel temperature of 104 K. The high-temperature phase...... observed between 104 K and 47.5 K is a binary magnetic structure where the holmium and erbium moments belong to different modulated c-axis spirals. The intermediate-temperature phase between 47.5 K and 35 K is a simple basal plane spiral. Below 35 K, the measurements suggest a ferrimagnetic structure...

  1. Parametric Powder Diffraction

    Science.gov (United States)

    David, William I. F.; Evans, John S. O.

    The rapidity with which powder diffraction data may be collected, not only at neutron and X-ray synchrotron facilities but also in the laboratory, means that the collection of a single diffraction pattern is now the exception rather than the rule. Many experiments involve the collection of hundreds and perhaps many thousands of datasets where a parameter such as temperature or pressure is varied or where time is the variable and life-cycle, synthesis or decomposition processes are monitored or three-dimensional space is scanned and the three-dimensional internal structure of an object is elucidated. In this paper, the origins of parametric diffraction are discussed and the techniques and challenges of parametric powder diffraction analysis are presented. The first parametric measurements were performed around 50 years ago with the development of a modified Guinier camera but it was the automation afforded by neutron diffraction combined with increases in computer speed and memory that established parametric diffraction on a strong footing initially at the ILL, Grenoble in France. The theoretical parameterisation of quantities such as lattice constants and atomic displacement parameters will be discussed and selected examples of parametric diffraction over the past 20 years will be reviewed that highlight the power of the technique.

  2. Dark diffusional enhancement of holographic multiplexed gratings in phenanthrenequinone doped poly(methyl methacrylate) photopolymer

    Science.gov (United States)

    Yu, Dan; Wang, Heng; Liu, Hong-Peng; Wang, Jian; Jiang, Yong-Yuan; Sun, Xiu-Dong

    2011-11-01

    In this paper, we experimentally investigate the dark diffusional enhancement of the optimized multiplexed grating in the phenanthrenequinone doped poly (methyl methacrylate) (PQ-PMMA) photopolymer. The possibility of improving the holographic characteristics of the material through the dark enhancement is demonstrated. The optimal preillumination exposure and the optimal time interval between exposures are extracted to obtain the optimized diffraction efficiency, and their values are 3.4×103 mJ/cm2 and 2 min, respectively. The dark enhancement of the multiplexed grating is presented as an effective method to improve the response region and the dynamic range and to prevent saturation of the material. The dependence of the phenanthrenequinone concentration on the increment of the refractive index modulation is quantitatively studied, which provides a significant basis for improving the homogeneity in the multiplexed gratings using a quantitative strategy. Finally, a simple experimental procedure using the dark enhancement is introduced to improve the homogeneity of the diffraction efficiency and to avoid the complex schedule exposure.

  3. Development of a large mosaic volume phase holographic (VPH) grating for APOGEE

    Science.gov (United States)

    Arns, James; Wilson, John C.; Skrutskie, Mike; Smee, Steve; Barkhouser, Robert; Eisenstein, Daniel; Gunn, Jim; Hearty, Fred; Harding, Al; Maseman, Paul; Holtzman, Jon; Schiavon, Ricardo; Gillespie, Bruce; Majewski, Steven

    2010-07-01

    Volume phase holographic (VPH) gratings are increasingly being used as diffractive elements in astronomical instruments due to their potential for very high peak diffraction efficiencies and the possibility of a compact instrument design when the gratings are used in transmission. Historically, VPH grating (VPHG) sizes have been limited by the size of manufacturer's holographic recording optics. We report on the design, specification and fabrication of a large, 290 mm × 475 mm elliptically-shaped, mosaic VPHG for the Apache Point Observatory Galactic Evolution Experiment (APOGEE) spectrograph. This high-resolution near-infrared multi-object spectrograph is in construction for the Sloan Digital Sky Survey III (SDSS III). The 1008.6 lines/mm VPHG was designed for optimized performance over a wavelength range from 1.5 to 1.7 μm. A step-and-repeat exposure method was chosen to fabricate a three-segment mosaic on a 305 mm × 508 mm monolithic fused-silica substrate. Specification considerations imposed on the VPHG to assure the mosaic construction will satisfy the end use requirements are discussed. Production issues and test results of the mosaic VPHG are discussed.

  4. PROTECTIVE COATINGS OF FIBER BRAGG GRATING FOR MINIMIZING OF MECHANICAL IMPACT ON ITS WAVELENGTH CHARACTERISTICS

    Directory of Open Access Journals (Sweden)

    A. S. Munko

    2015-03-01

    Full Text Available The paper deals with the scheme for the study of the Bragg wavelength shift dependence on the applied tensile force. Samples of fiber Bragg gratings with different coatings have been studied: the restored acrylate coating, the heatshrinkable fusion splice protection sleeve without metal rod, the heat-shrinkable fusion splice protection sleeve with a metal rod, the metal capillary, polyvinylchloride tube. For different coatings of diffractive structure, dependences of wavelength shift for the Bragg grating resonance have been obtained on the tensile strength applied to the ends of an optical fiber. It was determined that the studied FBG coatings give the possibility to reduce the mechanical impact on the Bragg wavelength shift for 1.1-15 times as compared to an uncoated waveguide. The most effective version of coated fiber Bragg grating is the heatshrinkable fusion splice protection sleeve with a metal rod. When the force (equal to 6 N is applied to the 100 mm optical fiber area with the inscribed diffractive structure, the Bragg wavelength shift is 7.5 nm for the unprotected sample and 0.5 nm for the one coated with the heat-shrinkable fusion splice protection sleeve.

  5. Non-diffractive waves

    CERN Document Server

    Hernandez-Figueroa, Hugo E; Recami, Erasmo

    2013-01-01

    This continuation and extension of the successful book ""Localized Waves"" by the same editors brings together leading researchers in non-diffractive waves to cover the most important results in their field and as such is the first to present the current state.The well-balanced presentation of theory and experiments guides readers through the background of different types of non-diffractive waves, their generation, propagation, and possible applications. The authors include a historical account of the development of the field, and cover different types of non-diffractive waves, including Airy

  6. Diffraction. Powder, amorphous, liquid

    International Nuclear Information System (INIS)

    Sosnowska, I.M.

    1999-01-01

    Neutron powder diffraction is a unique tool to observe all possible diffraction effects appearing in crystal. High-resolution neutron diffractometers have to be used in this study. Analysis of the magnetic structure of polycrystalline materials requires the use of high-resolution neutron diffraction in the range of large interplanar distances. As distinguished from the double axis diffractometers (DAS), which show high resolution only at small interplanar distances, TOF (time-of-flight) diffractometry offers the best resolution at large interplanar distances. (K.A.)

  7. Theoretical modeling and design of photonic structures in zeolite nanocomposites for gas sensing. Part I: surface relief gratings.

    Science.gov (United States)

    Cody, D; Naydenova, I

    2017-12-01

    The suitability of holographic structures fabricated in zeolite nanoparticle-polymer composite materials for gas sensing applications has been investigated. Theoretical modeling of the sensor response (i.e., change in hologram readout due to a change in refractive index modulation or thickness as a result of gas adsorption) of different sensor designs was carried out using Raman-Nath theory and Kogelnik's coupled wave theory. The influence of a range of parameters on the sensor response of holographically recorded surface and volume photonic grating structures has been studied, namely the phase difference between the diffracted and probe beam introduced by the grating, grating geometry, thickness, spatial frequency, reconstruction wavelength, and zeolite nanoparticle refractive index. From this, the optimum fabrication conditions for both surface and volume holographic gas sensor designs have been identified. Here, in part I, results from theoretical modeling of the influence of design on the sensor response of holographically inscribed surface relief structures for gas sensing applications is reported.

  8. Design of two-dimensional (crossed) grating calculation in Czerny-Turner spectrometer with usage of freeform mirrors

    Science.gov (United States)

    Bazhanov, Yury; Demura, Elena; Cherkashina, Rasima; Vlahco, Vadim

    2017-08-01

    The possibility of building a spectrometer based on a flat two-dimensional (crossed) grating is being considered. The most suitable layout for this is the Czerny - Turner, where a spectral image lies in the plane. In this paper an attempt to compensate for the transverse aberrations is made by using a diffraction grating with variable spacing grooves in both sections and aspheric mirror elements of layout, including ones having a freeform surface. Using crossed grating greatly simplifies the device layout and may be particularly effective when used in the ultraviolet and infrared regions of the spectrum, due to a small choice of transmissive materials for manufacturing spectral prisms. This paper gives examples of such case.

  9. Plane gratings for high-resolution grazing-incidence monochromators: holographic grating versus mechanically ruled varied-line-spacing grating

    International Nuclear Information System (INIS)

    Koike, Masato; Namioka, Takeshi

    1997-01-01

    Comparative studies have been made on the holographic plane grating and the ruled varied-line-spacing (VLS) plane grating designed for two kinds of objective Monk - Gillieson type high-resolution grazing incidence monochromator, I and II. The ray-traced performance of monochromator types I and II on a synchrotron radiation beam line was evaluated in terms of resolving power and spectral purity by the introduction of new concepts of effective Gaussian line and purity profiles. The resolving power defined on the basis of the effective Gaussian profile is consistent with the spectral purity of the beam emerging from the exit slit and is more realistic as compared with those defined in the conventional manner, especially when spectral images have asymmetric profiles. It is concluded that holographic plane gratings recorded with a spherical and an aspheric wave front are capable of providing high resolution with high spectral purity and are fully interchangeable with the corresponding ruled VLS plane gratings. This interchangeability provides more flexibility for users in choosing a proper grating for a high-resolution grazing incidence monochromator of the Monk - Gillieson type. copyright 1997 Optical Society of America

  10. Polymer planar Bragg grating for sensing applications

    Science.gov (United States)

    Rosenberger, M.; Hartlaub, N.; Koller, G.; Belle, S.; Schmauss, B.; Hellmann, R.

    2013-05-01

    Bragg gratings have become indispensable as optical sensing elements and are already used for a variety of technical applications. Mainly silica fiber Bragg gratings (FBGs) have been extensively studied over the last decades and are nowadays commercially available. Bragg grating sensors consisting of other materials like polymers, however, have only recently come into the focus of fundamental and applied research. Polymers exhibit significantly different properties advantageous for many sensing applications and therefore provide a good alternative to silica based devices. In addition, polymer materials are inexpensive, simple to handle as well as available in various forms like liquid resists or bulk material. Accordingly, polymer integrated optics attract increasing interest and can serve as a substitute for optical fibers. We report on the fabrication of a planar Bragg grating sensor in bulk Polymethylmethacrylate (PMMA). The sensor consists of an optical waveguide and a Bragg grating, both written simultaneously into a PMMA chip by a single writing step, for which a phase mask covered by an amplitude mask is placed on top of the PMMA and exposed to the UV radiation of a KrF excimer laser. Depending on the phase mask period, different Bragg gratings reflecting in the telecommunication wavelength range are fabricated and characterized. Reflection and transmission measurements show a narrow reflection band and a high reflectivity of the polymer planar Bragg grating (PPBG). After connecting to a single mode fiber, the portable PPBG based sensor was evaluated for different measurands like humidity and strain. The sensor performance was compared to already existing sensing systems. Due to the obtained results as well as the rapid and cheap fabrication of the sensor chip, the PPBG qualifies for a low cost sensing element.

  11. Binary Neutron Star Mergers

    Directory of Open Access Journals (Sweden)

    Joshua A. Faber

    2012-07-01

    Full Text Available We review the current status of studies of the coalescence of binary neutron star systems. We begin with a discussion of the formation channels of merging binaries and we discuss the most recent theoretical predictions for merger rates. Next, we turn to the quasi-equilibrium formalisms that are used to study binaries prior to the merger phase and to generate initial data for fully dynamical simulations. The quasi-equilibrium approximation has played a key role in developing our understanding of the physics of binary coalescence and, in particular, of the orbital instability processes that can drive binaries to merger at the end of their lifetimes. We then turn to the numerical techniques used in dynamical simulations, including relativistic formalisms, (magneto-hydrodynamics, gravitational-wave extraction techniques, and nuclear microphysics treatments. This is followed by a summary of the simulations performed across the field to date, including the most recent results from both fully relativistic and microphysically detailed simulations. Finally, we discuss the likely directions for the field as we transition from the first to the second generation of gravitational-wave interferometers and while supercomputers reach the petascale frontier.

  12. Skewed Binary Search Trees

    DEFF Research Database (Denmark)

    Brodal, Gerth Stølting; Moruz, Gabriel

    2006-01-01

    It is well-known that to minimize the number of comparisons a binary search tree should be perfectly balanced. Previous work has shown that a dominating factor over the running time for a search is the number of cache faults performed, and that an appropriate memory layout of a binary search tree...... can reduce the number of cache faults by several hundred percent. Motivated by the fact that during a search branching to the left or right at a node does not necessarily have the same cost, e.g. because of branch prediction schemes, we in this paper study the class of skewed binary search trees....... For all nodes in a skewed binary search tree the ratio between the size of the left subtree and the size of the tree is a fixed constant (a ratio of 1/2 gives perfect balanced trees). In this paper we present an experimental study of various memory layouts of static skewed binary search trees, where each...

  13. Techniques for writing and reading data on an optical disk which include formation of holographic optical gratings in plural locations on the optical disk

    Science.gov (United States)

    Liu, Tsuen-Hsi (Inventor); Psaltis, Demetri (Inventor); Mok, Fai H. (Inventor); Zhou, Gan (Inventor)

    2005-01-01

    An optical memory for storing and/or reading data on an optical disk. The optical disk incorporates a material in which holographic gratings can be created, and subsequently detected, at plural locations within the disk by an electro-optical head. Creation and detection of holographic gratings with variable diffraction efficiency is possible with the electro-optical head. Multiple holographic gratings can also be created at each one of the plural locations via a beam of light which has a different wavelength or point of focus. These data elements can be read by the electro-optical head using a beam of light sequentially varied in wavelength or point of focus to correspond to the multiple holographic gratings to be recorded.

  14. Perturbative approach to continuum generation in a fiber Bragg grating.

    Science.gov (United States)

    Westbrook, P S; Nicholson, J W

    2006-08-21

    We derive a perturbative solution to the nonlinear Schrödinger equation to include the effect of a fiber Bragg grating whose bandgap is much smaller than the pulse bandwidth. The grating generates a slow dispersive wave which may be computed from an integral over the unperturbed solution if nonlinear interaction between the grating and unperturbed waves is negligible. Our approach allows rapid estimation of large grating continuum enhancement peaks from a single nonlinear simulation of the waveguide without grating. We apply our method to uniform and sampled gratings, finding good agreement with full nonlinear simulations, and qualitatively reproducing experimental results.

  15. Diffraction at TOTEM

    CERN Document Server

    Giani, S; Antchev, G; Aspell, P; Avati, V; Bagliesi, M G; Berardi, V; Berretti, M; Besta, M; Bozzo, M; Brücken, E; Buzzo, A; Cafagna, F; Calicchio, M; Catanesi, M G; Cecchi, R; Ciocci, M A; Dadel, P; Deile, M; Dimovasili, E; Eggert, K; Eremin, V; Ferro, F; Fiergolski, A; García, F; Greco, V; Grzanka, L; Heino, J; Hildén, T; Kaspar, J; Kopal, J; Kundrát, V; Kurvinen, K; Lami, S; Latino, G; Lauhakangas, R; Leszko, R; Lippmaa, E; Lokajícek, M; Lo Vetere, M; Lucas Rodriguez, F; Macrí, M; Magazzù, G; Meucci, M; Minutoli, S; Notarnicola, G; Oliveri, E; Oljemark, F; Orava, R; Oriunno, M; Österberg, K; Pedreschi, E; Petäjäjärvi, J; Prochazka, J; Quinto, M; Radermacher, E; Radicioni, E; Ravotti, F; Rella, G; Robutti, E; Ropelewski, L; Rostkowski, M; Ruggiero, G; Rummel, A; Saarikko, H; Sanguinetti, G; Santroni, A; Scribano, A; Sette, G; Snoeys, W; Spinella, F; Ster, A; Taylor, C; Trummal, A; Turini, N; Whitmore, J; Wu, J; Zalewski, M

    2010-01-01

    The primary objective of the TOTEM experiment at the LHC is the measurement of the total proton-proton cross section with the luminosity-independent method and the study of elastic proton-proton cross-section over a wide |t|-range. In addition TOTEM also performs a comprehensive study of diffraction, spanning from cross-section measurements of individual diffractive processes to the analysis of their event topologies. Hard diffraction will be studied in collaboration with CMS taking advantage of the large common rapidity coverage for charged and neutral particle detection and the large variety of trigger possibilities even at large luminosities. TOTEM will take data under all LHC beam conditions including standard high luminosity runs to maximise its physics reach. This contribution describes the main features of the TOTEM diffractive physics programme including measurements to be made in the early LHC runs.

  16. Diffraction at TOTEM

    CERN Document Server

    Antchev, G.; Avati, V.; Bagliesi, M.G.; Berardi, V.; Berretti, M.; Bottigli, U.; Bozzo, M.; Brucken, E.; Buzzo, A.; Cafagna, F.; Calicchio, M.; Catanesi, M.G.; Catastini, P.L.; Cecchi, R.; Ciocci, M.A.; Deile, M.; Dimovasili, E.; Eggert, K.; Eremin, V.; Ferro, F.; Garcia, F.; Giani, S.; Greco, V.; Heino, J.; Hilden, T.; Kaspar, J.; Kopal, J.; Kundrat, V.; Kurvinen, K.; Lami, S.; Latino, G.; Lauhakangas, R.; Lippmaa, E.; Lokajicek, M.; Lo Vetere, M.; Lucas Rodriguez, F.; Macri, M.; Magazzu, G.; Meucci, M.; Minutoli, S.; Niewiadomski, H.; Noschis, E.; Notarnicola, G.; Oliveri, E.; Oljemark, F.; Orava, R.; Oriunno, M.; Osterberg, K.; Palazzi, P.; Pedreschi, E.; Petajajarvi, J.; Quinto, M.; Radermacher, E.; Radicioni, E.; Ravotti, F.; Rella, G.; Robutti, E.; Ropelewski, L.; Ruggiero, G.; Rummel, A.; Saarikko, H.; Sanguinetti, G.; Santroni, A.; Scribano, A.; Sette, G.; Snoeys, W.; Spinella, F.; Squillacioti, P.; Ster, A.; Taylor, C.; Trummal, A.; Turini, N.; Whitmore, J.; Wu, J.

    2009-01-01

    The TOTEM experiment at the LHC measures the total proton-proton cross section with the luminosity-independent method and the elastic proton-proton cross-section over a wide |t|-range. It also performs a comprehensive study of diffraction, spanning from cross-section measurements of individual diffractive processes to the analysis of their event topologies. Hard diffraction will be studied in collaboration with CMS taking advantage of the large common rapidity coverage for charged and neutral particle detection and the large variety of trigger possibilities even at large luminosities. TOTEM will take data under all LHC beam conditions including standard high luminosity runs to maximize its physics reach. This contribution describes the main features of the TOTEM physics programme including measurements to be made in the early LHC runs. In addition, a novel scheme to extend the diffractive proton acceptance for high luminosity runs by installing proton detectors at IP3 is described.

  17. Modelling binary data

    CERN Document Server

    Collett, David

    2002-01-01

    INTRODUCTION Some Examples The Scope of this Book Use of Statistical Software STATISTICAL INFERENCE FOR BINARY DATA The Binomial Distribution Inference about the Success Probability Comparison of Two Proportions Comparison of Two or More Proportions MODELS FOR BINARY AND BINOMIAL DATA Statistical Modelling Linear Models Methods of Estimation Fitting Linear Models to Binomial Data Models for Binomial Response Data The Linear Logistic Model Fitting the Linear Logistic Model to Binomial Data Goodness of Fit of a Linear Logistic Model Comparing Linear Logistic Models Linear Trend in Proportions Comparing Stimulus-Response Relationships Non-Convergence and Overfitting Some other Goodness of Fit Statistics Strategy for Model Selection Predicting a Binary Response Probability BIOASSAY AND SOME OTHER APPLICATIONS The Tolerance Distribution Estimating an Effective Dose Relative Potency Natural Response Non-Linear Logistic Regression Models Applications of the Complementary Log-Log Model MODEL CHECKING Definition of Re...

  18. Evolution of dwarf binaries

    International Nuclear Information System (INIS)

    Tutukov, A.V.; Fedorova, A.V.; Yungel'son, L.R.

    1982-01-01

    The conditions of mass exchange in close binary systems with masses of components less or equal to one solar mass have been analysed for the case, when the system radiates gravitational waves. It has been shown that the mass exchange rate depends in a certain way on the mass ratio of components and on the mass of component that fills its inner critical lobe. The comparison of observed periods, masses of contact components, and mass exchange rates of observed cataclysmic binaries have led to the conclusion that the evolution of close binaries WZ Sge, OY Car, Z Cha, TT Ari, 2A 0311-227, and G 61-29 may be driven by the emission of gravitational waves [ru

  19. Evolution of dwarf binaries

    International Nuclear Information System (INIS)

    Tutukov, A.V.; Fedorova, A.V.; Yungel'son, L.R.

    1982-01-01

    The circumstances of mass exchange in close binary systems whose components have a mass < or approx. =1 M/sub sun/ are analyzed for the case where the system is losing orbital angular momentum by radiation of gravitational waves. The mass exchange rate will depend on the mass ratio of the components and on the mass of the component that is overfilling its critical Roche lobe. A comparison of the observed orbital periods, masses of the components losing material, and mass exchange rates against the theoretical values for cataclysmic binaries indicates that the evolution of the close binaries WZ Sge, OY Car, Z Cha, TT Ari, 2A 0311-227, and G61-29 may be driven by the emission of gravitational waves

  20. Binary and Millisecond Pulsars

    Directory of Open Access Journals (Sweden)

    Lorimer Duncan R.

    2008-11-01

    Full Text Available We review the main properties, demographics and applications of binary and millisecond radio pulsars. Our knowledge of these exciting objects has greatly increased in recent years, mainly due to successful surveys which have brought the known pulsar population to over 1800. There are now 83 binary and millisecond pulsars associated with the disk of our Galaxy, and a further 140 pulsars in 26 of the Galactic globular clusters. Recent highlights include the discovery of the young relativistic binary system PSR J1906+0746, a rejuvination in globular cluster pulsar research including growing numbers of pulsars with masses in excess of 1.5M_⊙, a precise measurement of relativistic spin precession in the double pulsar system and a Galactic millisecond pulsar in an eccentric (e = 0.44 orbit around an unevolved companion.

  1. X-ray diffraction 2 - diffraction principles

    International Nuclear Information System (INIS)

    O'Connor, B.

    1999-01-01

    Full text: The computation of powder diffraction intensities is based on the principle that the powder pattern comprises the summation of the intensity contributions from each of the crystallites (or single crystals) in the material. Therefore, it is of value for powder diffractionists to appreciate the form of the expression for calculating single crystal diffraction pattern intensities. This knowledge is especially important for Rietveld analysis practitioners in terms of the (i) mathematics of the method and (ii) retrieving single crystal structure data from the literature. We consider the integrated intensity from a small single crystal being rotated at velocity ω through the Bragg angle θ for reflection (hkl).... I(hkl) = [l o /ω]. [e 4 /m 2 c 4 ]. [λ 3 δV F(hkl) 2 /υ 2 ].[(1+cos 2 2θ)/2sin2θ] where e, m and c are the usual fundamental constants; λ is the x-ray wavelength, δV is the crystallite volume; F(hkl) is the structure factor; υ is the unit cell volume; and (1+cos 2 θ)/2sin2θ] is the Lorentz-polarisation factor for an unpolarised incident beam. The expression does not include a contribution for extinction. The influence of factors λ, δV, F(hkl) and υ on the intensities should be appreciated by powder diffractionists, especially the structure factor, F(hkl), which is responsible for the fingerprint nature of diffraction patterns, such as the rise and fall of intensity from peak to peak. The structure factor expression represents the summation of the scattered waves from each of the j scattering centres (i e atoms) in the unit cell: F(hkl) Σ f j exp[2πi (h.x j +k.y i +l. z i )] T j . Symbol f is the scattering factor (representing the atom-type scattering efficiency); (x, y, z) are the fractional position coordinates of atom j within the unit cell; and T is the thermal vibration factor for the atom given by: T j = 8π 2 2 > sin 2 θ/λ 2 with 2 > being the mean-square vibration amplitude of the atom (assumed to be isotropic). The

  2. The Brightest Binaries

    Science.gov (United States)

    Vanbeveren, D., Van Rensbergen, W., De Loore, C.

    Massive stars are distributed all over the upper part of the Hertzsprung-Russell diagram according to their subsequent phases of stellar evolution from main sequence to supernova. Massive stars may either be single or they may be a component of a close binary. The observed single star/binary frequency is known only in a small part of the Galaxy. Whether this holds for the whole galaxy or for the whole cosmos is questionable and needs many more high quality observations. Massive star evolution depends critically on mass loss by stellar wind and this stellar wind mass loss may change dramatically when stars evolve from one phase to another. We start the book with a critical discussion of observations of the different types of massive stars, observations that are of fundamental importance in relation to stellar evolution, with special emphasis on mass loss by stellar wind. We update our knowledge of the physics that models the structure and evolution of massive single stars and we present new calculations. The conclusions resulting from a comparison between these calculations and observations are then used to study the evolution of massive binaries. This book provides our current knowledge of a great variety of massive binaries, and hence of a great variety of evolutionary phases. A large number of case studies illustrates the existence of these phases. Finally, we present the results of massive star population number synthesis, including the effect of binaries. The results indicate that neglecting them leads to a conclusion which may be far from reality. This book is written for researchers in massive star evolution. We hope that, after reading this book, university-level astrophysics students will become fascinated by the exciting world of the `Brightest Binaries'.

  3. Femtosecond laser induced crystallization and permanent relief grating structures in amorphous inorganic (In2O3+1 wt % TiO2) films

    International Nuclear Information System (INIS)

    Katayama, Shigeru; Tsutsumi, Naoto; Nakamura, Toshitaka; Horiike, Mika; Hirao, Kazuyuki

    2002-01-01

    This letter presents an investigation of crystalline relief grating structures induced by irradiation of near-infrared femtosecond laser pulses on an amorphous inorganic (In 2 O 3 +1 wt % TiO 2 ) film. The shapes of crystallized relief structures were sensitive to the scanning rate and the focused point height of irradiation, and the optimized irradiation condition gave cone-shaped cross section structures. Selective wet etching on unirradiated amorphous regions using a 3% hydrochloric acid solution could make sharper relief grating structures of crystalline regions. Diffraction efficiency of the relief grating structures with Au coating was measured, and it was confirmed that first-order diffraction, efficiencies were approximately 40% and 20% for etched and nonetched samples, respectively

  4. Hyperspectral grating optimization and manufacturing considerations

    Science.gov (United States)

    Ziph-Schatzberg, Leah; Swartz, Barry; Warren, Chris; Santman, Jeff; Saleh, Mohammad; Wiggins, Richard; Crifasi, Joe; Comstock, Lovell; Taylor, Kevan

    2015-06-01

    Hyperspectral imaging systems are finding broader applications in both the commercial and aerospace markets. It is becoming clear that to optimize the performance of these systems, their instrument transfer function needs to be tailored for each application. Vis-SWIR systems in the full 400nm to 2500nm waveband present particular design and manufacturing challenges. A single blazed grating is inadequate for a system operating in the full vis-SWIR wavelength range. In addition, optical materials and broad band coatings present a challenge for non-reflective systems. An understanding of the application and wavelengths of interest, combined with a judicious choice of a focal plane array, can then lead to an optimized system for the specific application. The ability to tailor the grating and manufacture a wide variety of grating profiles and substrate shapes becomes a significant performance enabler. This paper will discuss how the use of optical, coating, and grating design/analysis software, combined with grating manufacturing techniques assure meeting high performance requirements for different applications.

  5. Photo-induced refractive index and topographical surface gratings in functionalized nanocarbon solid film

    Energy Technology Data Exchange (ETDEWEB)

    McGee, David J.; Ferrie, John; Plachy, Aljoscha [Department of Physics, The College of New Jersey, Ewing, New Jersey 08628 (United States); Joo, Yongho; Choi, Jonathan; Kanimozhi, Catherine; Gopalan, Padma, E-mail: pgopalan@cae.wisc.edu [Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

    2015-11-02

    We demonstrate that a single-walled carbon nanotube network noncovalently coupled with a pyrene-modified azo-benzene chromophore functions as a host matrix for a broad range of photo-orientation and photomechanical effects. The chromophore could be efficiently reoriented through repeated trans-cis-trans isomerization under linearly polarized 480 nm light, with Δn of 0.012 at 650 nm and fast characteristic rise-times of 0.12 s. Erasable phase diffraction gratings could also be written, with permanent surface relief gratings forming at sufficiently long irradiation times. In addition to demonstrating a mechanism for photo-manipulation of single-walled carbon nanotubes, these results show photo-orientation of chromophores in azo-functionalized single-walled carbon nanotube networks as a path towards the photosensitive tuning of the electrostatic environment of the nanotube.

  6. Revisiting Bragg's X-ray microscope: scatter based optical transient grating detection of pulsed ionising radiation.

    Science.gov (United States)

    Fullagar, Wilfred K; Paganin, David M; Hall, Chris J

    2011-06-01

    Transient optical gratings for detecting ultrafast signals are routine for temporally resolved photochemical investigations. Many processes can contribute to the formation of such gratings; we indicate use of optically scattering centres that can be formed with highly variable latencies in different materials and devices using ionising radiation. Coherent light scattered by these centres can form the short-wavelength-to-optical-wavelength, incoherent-to-coherent basis of a Bragg X-ray microscope, with inherent scope for optical phasing. Depending on the dynamics of the medium chosen, the way is open to both ultrafast pulsed and integrating measurements. For experiments employing brief pulses, we discuss high-dynamic-range short-wavelength diffraction measurements with real-time optical reconstructions. Applications to optical real-time X-ray phase-retrieval are considered. Copyright © 2010 Elsevier B.V. All rights reserved.

  7. Photo-induced refractive index and topographical surface gratings in functionalized nanocarbon solid film

    International Nuclear Information System (INIS)

    McGee, David J.; Ferrie, John; Plachy, Aljoscha; Joo, Yongho; Choi, Jonathan; Kanimozhi, Catherine; Gopalan, Padma

    2015-01-01

    We demonstrate that a single-walled carbon nanotube network noncovalently coupled with a pyrene-modified azo-benzene chromophore functions as a host matrix for a broad range of photo-orientation and photomechanical effects. The chromophore could be efficiently reoriented through repeated trans-cis-trans isomerization under linearly polarized 480 nm light, with Δn of 0.012 at 650 nm and fast characteristic rise-times of 0.12 s. Erasable phase diffraction gratings could also be written, with permanent surface relief gratings forming at sufficiently long irradiation times. In addition to demonstrating a mechanism for photo-manipulation of single-walled carbon nanotubes, these results show photo-orientation of chromophores in azo-functionalized single-walled carbon nanotube networks as a path towards the photosensitive tuning of the electrostatic environment of the nanotube

  8. Photo-induced refractive index and topographical surface gratings in functionalized nanocarbon solid film

    Science.gov (United States)

    McGee, David J.; Ferrie, John; Plachy, Aljoscha; Joo, Yongho; Choi, Jonathan; Kanimozhi, Catherine; Gopalan, Padma

    2015-11-01

    We demonstrate that a single-walled carbon nanotube network noncovalently coupled with a pyrene-modified azo-benzene chromophore functions as a host matrix for a broad range of photo-orientation and photomechanical effects. The chromophore could be efficiently reoriented through repeated trans-cis-trans isomerization under linearly polarized 480 nm light, with Δn of 0.012 at 650 nm and fast characteristic rise-times of 0.12 s. Erasable phase diffraction gratings could also be written, with permanent surface relief gratings forming at sufficiently long irradiation times. In addition to demonstrating a mechanism for photo-manipulation of single-walled carbon nanotubes, these results show photo-orientation of chromophores in azo-functionalized single-walled carbon nanotube networks as a path towards the photosensitive tuning of the electrostatic environment of the nanotube.

  9. Encounters of binaries

    International Nuclear Information System (INIS)

    Mikkola, S.

    1983-01-01

    Gravitational encounters of pairs of binaries have been studied numerically. Various cross-sections have been calculated for qualitative final results of the interaction and for energy transfer between the binding energy and the centre of mass kinetic energy. The distribution of the kinetic energies, resulting from the gravitational collision, were found to be virtually independent of the impact velocity in the case of collision of hard binaries. It was found that one out of five collisions, which are not simple fly-by's, leads to the formation of a stable three-body system. (author)

  10. Binary and Millisecond Pulsars

    Directory of Open Access Journals (Sweden)

    Duncan R. Lorimer

    1998-09-01

    Full Text Available Our knowledge of binary and millisecond pulsars has greatly increased in recent years. This is largely due to the success of large-area surveys which have brought the known population of such systems in the Galactic disk to around 50. As well as being interesting as a population of astronomical sources, many pulsars turn out to be superb celestial clocks. In this review we summarise the main properties of binary and millisecond pulsars and highlight some of their applications to relativistic astrophysics.

  11. Binary and Millisecond Pulsars

    Directory of Open Access Journals (Sweden)

    Lorimer Duncan R.

    2005-11-01

    Full Text Available We review the main properties, demographics and applications of binary and millisecond radio pulsars. Our knowledge of these exciting objects has greatly increased in recent years, mainly due to successful surveys which have brought the known pulsar population to over 1700. There are now 80 binary and millisecond pulsars associated with the disk of our Galaxy, and a further 103 pulsars in 24 of the Galactic globular clusters. Recent highlights have been the discovery of the first ever double pulsar system and a recent flurry of discoveries in globular clusters, in particular Terzan 5.

  12. Electroactive subwavelength gratings (ESWGs) from conjugated polymers for color and intensity modulation

    Science.gov (United States)

    Bhuvana, Thiruvelu; Kim, Byeonggwan; Yang, Xu; Shin, Haijin; Kim, Eunkyoung

    2012-05-01

    Subwavelength gratings with electroactive polymers such as poly(3-hexylthiophene) (P3HT) and poly(3,4-propylenedioxythiophene-phenylene) (P(ProDOT-Ph)) controlled the color intensity for various visible colors of diffracted light in a single device. Under the illumination of a white light, at a fixed angle of incidence, the color intensity of the diffracted light was reversibly switched from the maximum value down to 15% (85% decrease) by applying -2 to 2 V due to electrochemical (EC) reaction. All spectral colors including red, green, and blue were generated by changing the angle of incidence, and the intensity of each color was modulated electrochemically at a single EC device. With electroactive subwavelength gratings (ESWGs) of P3HT, the maximum modulation of the color intensity was observed in the red-yellow quadrant in the CIE color plot, whereas for the ESWGs of P(ProDOT-Ph), the maximum modulation of the color intensity was observed in the yellow-green and green-blue quadrants. Both ESWGs showed a memory effect, keeping their color and intensity even after power was turned off for longer than 40 hours.Subwavelength gratings with electroactive polymers such as poly(3-hexylthiophene) (P3HT) and poly(3,4-propylenedioxythiophene-phenylene) (P(ProDOT-Ph)) controlled the color intensity for various visible colors of diffracted light in a single device. Under the illumination of a white light, at a fixed angle of incidence, the color intensity of the diffracted light was reversibly switched from the maximum value down to 15% (85% decrease) by applying -2 to 2 V due to electrochemical (EC) reaction. All spectral colors including red, green, and blue were generated by changing the angle of incidence, and the intensity of each color was modulated electrochemically at a single EC device. With electroactive subwavelength gratings (ESWGs) of P3HT, the maximum modulation of the color intensity was observed in the red-yellow quadrant in the CIE color plot, whereas for the

  13. Autostereoscopic three-dimensional display by combining a single spatial light modulator and a zero-order nulled grating

    Science.gov (United States)

    Su, Yanfeng; Cai, Zhijian; Liu, Quan; Lu, Yifan; Guo, Peiliang; Shi, Lingyan; Wu, Jianhong

    2018-04-01

    In this paper, an autostereoscopic three-dimensional (3D) display system based on synthetic hologram reconstruction is proposed and implemented. The system uses a single phase-only spatial light modulator to load the synthetic hologram of the left and right stereo images, and the parallax angle between two reconstructed stereo images is enlarged by a grating to meet the split angle requirement of normal stereoscopic vision. To realize the crosstalk-free autostereoscopic 3D display with high light utilization efficiency, the groove parameters of the grating are specifically designed by the rigorous coupled-wave theory for suppressing the zero-order diffraction, and then the zero-order nulled grating is fabricated by the holographic lithography and the ion beam etching. Furthermore, the diffraction efficiency of the fabricated grating is measured under the illumination of a laser beam with a wavelength of 532 nm. Finally, the experimental verification system for the proposed autostereoscopic 3D display is presented. The experimental results prove that the proposed system is able to generate stereoscopic 3D images with good performances.

  14. Simulation and analysis of grating-integrated quantum dot infrared detectors for spectral response control and performance enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Oh Kim, Jun [Center for High Technology Materials, University of New Mexico, Albuquerque, New Mexico 87106 (United States); Division of Industrial Metrology, Korea Research Institute of Standards and Science, Daejeon 305-340 (Korea, Republic of); Ku, Zahyun; Urbas, Augustine, E-mail: youngchul.jun@inha.ac.kr, E-mail: Augustine.Urbas@wpafb.af.mil [Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433 (United States); Krishna, Sanjay [Center for High Technology Materials, University of New Mexico, Albuquerque, New Mexico 87106 (United States); Kang, Sang-Woo; Jun Lee, Sang [Division of Industrial Metrology, Korea Research Institute of Standards and Science, Daejeon 305-340 (Korea, Republic of); Chul Jun, Young, E-mail: youngchul.jun@inha.ac.kr, E-mail: Augustine.Urbas@wpafb.af.mil [Department of Physics, Inha University, Incheon 402-751 (Korea, Republic of)

    2014-04-28

    We propose and analyze a novel detector structure for pixel-level multispectral infrared imaging. More specifically, we investigate the device performance of a grating-integrated quantum dots-in-a-well photodetector under backside illumination. Our design uses 1-dimensional grating patterns fabricated directly on a semiconductor contact layer and, thus, adds a minimal amount of additional effort to conventional detector fabrication flows. We show that we can gain wide-range control of spectral response as well as large overall detection enhancement by adjusting grating parameters. For small grating periods, the spectral responsivity gradually changes with parameters. We explain this spectral tuning using the Fabry–Perot resonance and effective medium theory. For larger grating periods, the responsivity spectra get complicated due to increased diffraction into the active region, but we find that we can obtain large enhancement of the overall detector performance. In our design, the spectral tuning range can be larger than 1 μm, and, compared to the unpatterned detector, the detection enhancement can be greater than 92% and 148% for parallel and perpendicular polarizations. Our work can pave the way for practical, easy-to-fabricate detectors, which are highly useful for many infrared imaging applications.

  15. Fabrication and characterization of the source grating for visibility improvement of neutron phase imaging with gratings.

    Science.gov (United States)

    Kim, Jongyul; Lee, Kye Hong; Lim, Chang Hwy; Kim, Taejoo; Ahn, Chi Won; Cho, Gyuseong; Lee, Seung Wook

    2013-06-01

    The fabrication of gratings including metal deposition processes for highly neutron absorbing lines is a critical issue to achieve a good visibility of the grating-based phase imaging system. The source grating for a neutron Talbot-Lau interferometer is an array of Gadolinium (Gd) structures that are generally made by sputtering, photo-lithography, and chemical wet etching. However, it is very challenging to fabricate a Gd structure with sufficient neutron attenuation of approximately more than 20 μm using a conventional metal deposition method because of the slow Gd deposition rate, film stress, high material cost, and so on. In this article, we fabricated the source gratings for neutron Talbot-Lau interferometers by filling the silicon structure with Gadox particles. The new fabrication method allowed us a very stable and efficient way to achieve a much higher Gadox filled structure than a Gd film structure, and is even more suitable for thermal polychromatic neutrons, which are more difficult to stop than cold neutrons. The newly fabricated source gratings were tested at the polychromatic thermal neutron grating interferometer system of HANARO at the Korea Atomic Energy Research Institute, and the visibilities and images from the neutron phase imaging system with the new source gratings were compared with those fabricated by a Gd deposition method.

  16. High-index-contrast subwavelength grating VCSEL

    DEFF Research Database (Denmark)

    Gilet, Philippe; Olivier, Nicolas; Grosse, Philippe

    2010-01-01

    In this article, we report our results on 980nm high-index-contrast subwavelength grating (HCG) VCSELs for optical interconnection applications. In our structure, a thin undoped HCG layer replaces a thick p-type Bragg mirror. The HCG mirror can feasibly achieve polarization-selective reflectivities...... close to 100%. The investigated structure consists of a HCG mirror with an underneath /4-thick oxide gap, four p-type GaAlAs/GaAs pairs for current spreading, three InGaAs/GaAs quantum wells, and an n-type GaAlAs/GaAs Bragg mirror. The HCG structure was defined by e-beam lithography and dry etching....... The current oxide aperture and the oxide gap underneath the HCG were simultaneously formed by the selective wet oxidation process. Compared to air-gap high contrast grating mirrors demonstrated elsewhere, our grating mirrors are particular since they are supported by thinner /4 aluminium oxide layer, and thus...

  17. Optically tunable chirped fiber Bragg grating.

    Science.gov (United States)

    Li, Zhen; Chen, Zhe; Hsiao, V K S; Tang, Jie-Yuan; Zhao, Fuli; Jiang, Shao-Ji

    2012-05-07

    This work presents an optically tunable chirped fiber Bragg grating (CFBG). The CFBG is obtained by a side-polished fiber Bragg grating (SPFBG) whose thickness of the residual cladding layer in the polished area (D(RC)) varies with position along the length of the grating, which is coated with a photoresponsive liquid crystal (LC) overlay. The reflection spectrum of the CFBG is tuned by refractive index (RI) modulation, which comes from the phase transition of the overlaid photoresponsive LC under ultraviolet (UV) light irradiation. The broadening in the reflection spectrum and corresponding shift in the central wavelength are observed with UV light irradiation density of 0.64mW/mm. During the phase transition of the photoresponsive LC, the RI increase of the overlaid LC leads to the change of the CFBG reflection spectrum and the change is reversible and repeatable. The optically tunable CFBGs have potential use in optical DWDM system and an all-fiber telecommunication system.

  18. Bragg Grating Optical Filters by UV Nanoimprinting

    Directory of Open Access Journals (Sweden)

    M. Casalboni

    2012-01-01

    Full Text Available Results on an optical waveguide filter operating in the near IR region are reported. The device consists of a hybrid sol-gel -based grating loaded waveguide, obtained through the merging of conventional photolithography and UV-nanoimprinting. Starting from submicrometric gratings, fabricated by electron beam lithography, a soft mould has been produced and the original structures were replicated onto sol-gel photosensitive films. A final photolithographic step allowed the production of grating-loaded channel waveguides. The devices were optically characterized by transmission measurements in the telecom range 1450–1590 nm. The filter extinction ratio is −11 dB and the bandwidth is 1.7 nm.

  19. Gratings in passive and active optical waveguides

    DEFF Research Database (Denmark)

    Berendt, Martin Ole

    1999-01-01

    mode losses confirmed. An elaborated grating model, including the detailed shape of the index modulation, has been developed. This model improves the interpretation of grating growth dynamic, which is of value to both; analysis of the UV imprinting set-ups, and to the investigation of photosensitivity...... attenuated. In either case the cladding mode coupling gives loss on the short wavelength side of the reflection band. The cladding mode coupling loss is a major problem for the utilization of fiber Bragg gratings in wavelength division multiplexed (WDM) system. In this project, a numerical model for cladding...... mode coupling has been developed. The model can predict the spectral location and size of coupling, for various fiber designs. By the aid of this modeling tool, a fiber has been optimized to give low cladding-mode losses. The optimized fiber has been produced and the predicted reduction of cladding...

  20. High Efficiency Low Scatter Echelle Grating, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — A high efficiency low scatter echelle grating will be developed using a novel technique of multiple diamond shaving cuts. The grating will have mirror surfaces on...

  1. Interacting binary stars

    International Nuclear Information System (INIS)

    Pringle, J.E.; Wade, R.A.

    1985-01-01

    This book reviews the theoretical and observational knowledge of interacting binary stars. The topics discussed embrace the following features of these objects: their orbits, evolution, mass transfer, angular momentum losses, X-ray emission, eclipses, variability, and other related phenomena. (U.K.)

  2. Equational binary decision diagrams

    NARCIS (Netherlands)

    J.F. Groote (Jan Friso); J.C. van de Pol (Jaco)

    2000-01-01

    textabstractWe incorporate equations in binary decision diagrams (BDD). The resulting objects are called EQ-BDDs. A straightforward notion of ordered EQ-BDDs (EQ-OBDD) is defined, and it is proved that each EQ-BDD is logically equivalent to an EQ-OBDD. Moreover, on EQ-OBDDs satisfiability and

  3. N-Bit Binary Resistor

    Science.gov (United States)

    Tcheng, Ping

    1989-01-01

    Binary resistors in series tailored to precise value of resistance. Desired value of resistance obtained by cutting appropriate traces across resistors. Multibit, binary-based, adjustable resistor with high resolution used in many applications where precise resistance required.

  4. Observations of binary stars by speckle interferometry

    International Nuclear Information System (INIS)

    Morgan, B.L.; Beckmann, G.K.; Scaddan, R.J.

    1980-01-01

    This is the second paper in a series describing observations of binary stars using the technique of speckle interferometry. Observations were made using the 2.5-m Isaac Newton Telescope and the 1-m telescope of the Royal Greenwich Observatory and the 1.9-m telescope of the South African Astronomical Observatory. The classical Rayleigh diffraction limits are 0.050 arcsec for the 2.5-m telescope, 0.065 arcsec for the 1.9-m telescope and 0.125 arcsec for the 1-m telescope, at a wavelength of 500 nm. The results of 29 measurements of 26 objects are presented. The objects include long period spectroscopic binaries from the 6th Catalogue of Batten, close visual binary systems from the 3rd Catalogue of Finsen and Worley and variable stars. Nine of the objects have not been previously resolved by speckle interferometry. New members are detected in the systems β Cep, p Vel and iota UMa. (author)

  5. Texture and neutron diffraction

    International Nuclear Information System (INIS)

    Szpunar, J.

    1976-01-01

    The neutron diffraction method has only recently become a tool for studying the structure of polycrystalline materials. There are some fields such as texture studies where this method offers several advantages over other more common methods. Texture is the main subject of the review. The current status of the theory or deformation and recrystallization texture is discussed briefly. Texture is then described with the aid of the ODF function. Finally, applications of the neutron diffraction method are discussed using several examples of textures measured in metals and in non-metallic materials. Other, less known applications of neutron diffraction are also given, e.g. in stress measurements. The neutron diffraction method is extremely useful for studying the texture of coarse-grained materials. This method provides information on the average texture in a large volume. This enables one to measure texture in the same specimen in which anisotropy of the physical roperties has been measured. Selected examples are provided in which correlations between elastic, plastic and magnetic properties of polycrystalline materials and their texture are pointed out. Texture was measured in all these cases using the neutron diffraction method. (author)

  6. Multiwavelength optical scatterometry of dielectric gratings

    KAUST Repository

    Yashina, Nataliya P.

    2012-08-01

    Modern scatterometry problems arising in the lithography production of periodic gratings are in the focus of the work. The performance capabilities of a novel theoretical and numerical modeling oriented to these problems are considered. The approach is based on rigorous solutions of 2-D initial boundary value problems of the gratings theory. The quintessence and advantage of the method is the possibility to perform an efficient analysis simultaneously and interactively both for steady state and transient processes of the resonant scattering of electromagnetic waves by the infinite and compact periodic structures. © 2012 IEEE.

  7. Reflectivity-modulated grating-mirror

    DEFF Research Database (Denmark)

    2012-01-01

    region in a layer structure comprising a p- and a n-doped semiconductor layer with an electrooptic material layer (12) arranged there between. The grating region comprises a grating structure formed by periodic perforations to change the refractive index periodically in directions normal...... a reflectivity with little or no out coupling and a reflectivity with normal out coupling, wherein lasing in the VCL is supported at both the first and the second reflectivity. As the out coupling mirror modulates the output, the lasing does not need to be modulated, and the invention provides the advantage...

  8. High brightness diode lasers controlled by volume Bragg gratings

    Science.gov (United States)

    Glebov, Leonid

    2017-02-01

    Volume Bragg gratings (VBGs) recorded in photo-thermo-refractive (PTR) glass are holographic optical elements that are effective spectral and angular filters withstanding high power laser radiation. Reflecting VBGs are narrow-band spectral filters while transmitting VBGs are narrow-band angular filters. The use of these optical elements in external resonators of semiconductor lasers enables extremely resonant feedback that provides dramatic spectral and angular narrowing of laser diodes radiation without significant power and efficiency penalty. Spectral narrowing of laser diodes by reflecting VBGs demonstrated in wide spectral region from near UV to 3 μm. Commercially available VBGs have spectral width ranged from few nanometers to few tens of picometers. Efficient spectral locking was demonstrated for edge emitters (single diodes, bars, modules, and stacks), vertical cavity surface emitting lasers (VCSELs), grating coupled surface emitting lasers (GCSELs), and interband cascade lasers (ICLs). The use of multiplexed VBGs provides multiwavelength emission from a single emitter. Spectrally locked semiconductor lasers demonstrated CW power from milliwatts to a kilowatt. Angular narrowing by transmitting VBGs enables single transverse mode emission from wide aperture diode lasers having resonators with great Fresnel numbers. This feature provides close to diffraction limit divergence along a slow axis of wide stripe edge emitters. Radiation exchange between lasers by means of spatially profiled or multiplexed VBGs enables coherent combining of diode lasers. Sequence of VBGs or multiplexed VBGs enable spectral combining of spectrally narrowed diode lasers or laser modules. Thus the use of VBGs for diode lasers beam control provides dramatic increase of brightness.

  9. Application of spherical gratings in synchrotron radiation spectroscopy

    International Nuclear Information System (INIS)

    Hogrefe, H.; Howells, M.R.; Hoyer, E.

    1986-05-01

    The recent development in gracing incidence grating monochromator design is discussed and the performance limiting for such instruments are examined. Especially the aberrations of toroidal and spherical gratings are investigated using the optical path function concept. It is shown that large radius spherical gratings, which can be produced with better slope tolerances than aspherics, also yield smaller overall line curvature than toroids. Therefore, a new simple spherical grating monochromator design is proposed and its performance is analyzed

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

    Science.gov (United States)

    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.

  11. Optically controlled tunable dispersion compensators based on pumped fiber gratings.

    Science.gov (United States)

    Shu, Xuewen; Sugden, Kate; Bennion, Ian

    2011-08-01

    We demonstrate optically tunable dispersion compensators based on pumping fiber Bragg gratings made in Er/Yb codoped fiber. The tunable dispersion for a chirped grating and also a uniform-period grating was successfully demonstrated in the experiment. The dispersion of the chirped grating was tuned from 900 to 1990 ps/nm and also from -600 to -950 ps/nm in the experiment. © 2011 Optical Society of America

  12. Space grating optical structure of the retina and RGB-color vision.

    Science.gov (United States)

    Lauinger, Norbert

    2017-02-01

    Diffraction of light at the spatial cellular phase grating outer nuclear layer of the retina could produce Fresnel near-field interferences in three RGB diffraction orders accessible to photoreceptors (cones/rods). At perpendicular light incidence the wavelengths of the RGB diffraction orders in photopic vision-a fundamental R-wave with two G+B-harmonics-correspond to the peak wavelengths of the spectral brightness sensitivity curves of the cones at 559 nmR, 537 nmG, and 447 nmB. In scotopic vision the R+G diffraction orders optically fuse at 512 nm, the peak value of the rod's spectral brightness sensitivity curve. The diffractive-optical transmission system with sender (resonator), space waves, and receiver antennae converts the spectral light components involved in imaging into RGB space. The colors seen at objects are diffractive-optical products in the eye, as the German philosopher A. Schopenhauer predicted. They are second related to the overall illumination in object space. The RGB transmission system is the missing link optically managing the spectral tuning of the RGB photopigments.

  13. Diffraction. Single crystal, magnetic

    International Nuclear Information System (INIS)

    Heger, G.

    1999-01-01

    The analysis of crystal structure and magnetic ordering is usually based on diffraction phenomena caused by the interaction of matter with X-rays, neutrons, or electrons. Complementary information is achieved due to the different character of X-rays, neutrons and electrons, and hence their different interactions with matter and further practical aspects. X-ray diffraction using conventional laboratory equipment and/or synchrotron installations is the most important method for structure analyses. The purpose of this paper is to discuss special cases, for which, in addition to this indispensable part, neutrons are required to solve structural problems. Even though the huge intensity of modern synchrotron sources allows in principle the study of magnetic X-ray scattering the investigation of magnetic structures is still one of the most important applications of neutron diffraction. (K.A.)

  14. Black holes in binary stars

    NARCIS (Netherlands)

    Wijers, R.A.M.J.

    1996-01-01

    Introduction Distinguishing neutron stars and black holes Optical companions and dynamical masses X-ray signatures of the nature of a compact object Structure and evolution of black-hole binaries High-mass black-hole binaries Low-mass black-hole binaries Low-mass black holes Formation of black holes

  15. Design and development of long-period grating sensors for ...

    Indian Academy of Sciences (India)

    Abstract. Long Period Gratings (LPGs) have been developed using carbon diox- ide laser in a standard optical fibre. LPGs with a periodicity of 600 μm and grating length of 24 mm have been inscribed on standard single mode fibre. Such gratings have been used in designing temperature sensors and temperature is ...

  16. 75 FR 41889 - Certain Steel Grating From China

    Science.gov (United States)

    2010-07-19

    ... COMMISSION Certain Steel Grating From China Determination On the basis of the record \\1\\ developed in the... steel grating from China, provided for in subheading 7308.90.70 of the Harmonized Tariff Schedule of the... imports of certain steel gratings from China were being subsidized within the meaning of section 703(b) of...

  17. 75 FR 8746 - Certain Steel Grating From China

    Science.gov (United States)

    2010-02-25

    ... COMMISSION Certain Steel Grating From China AGENCY: United States International Trade Commission. ACTION... retarded, by reason of subsidized and less-than-fair-value imports from China of certain steel gratings..., producers, or exporters ] in China of certain steel gratings, and that such products are being sold in the...

  18. HDE 245059: A WEAK-LINED T TAURI BINARY REVEALED BY CHANDRA AND KECK

    International Nuclear Information System (INIS)

    Baldovin-Saavedra, C.; Audard, M.; Duchene, G.; Guedel, M.; Skinner, S.L.; Paerels, F. B. S.; Ghez, A.; McCabe, C.

    2009-01-01

    We present the Chandra High Energy Transmission Grating Spectrometer and Keck observations of HDE 245059, a young weak-lined T Tauri star (WTTS), member of the pre-main-sequence group in the λ Orionis Cluster. Our high spatial resolution, near-infrared observations with Keck reveal that HDE 245059 is in fact a binary separated by 0.''87, probably composed of two WTTS based on their color indices. Based on this new information we have obtained an estimate of the masses of the binary components; ∼3 M sun and ∼2.5 M sun for the north and south components, respectively. We have also estimated the age of the system to be ∼2-3 Myr. We detect both components of the binary in the zeroth-order Chandra image and in the grating spectra. The light curves show X-ray variability of both sources and in particular a flaring event in the weaker southern component. The spectra of both stars show similar features: a combination of cool and hot plasma as demonstrated by several iron lines from Fe XVII to Fe XXV and a strong bremsstrahlung continuum at short wavelengths. We have fitted the combined grating and zeroth-order spectrum (considering the contribution of both stars) in XSPEC. The coronal abundances and emission measure distribution for the binary have been obtained using different methods, including a continuous emission measure distribution and a multi-temperature approximation. In all cases we have found that the emission is dominated by plasma between ∼8 and ∼15 MK a soft component at ∼4 MK and a hard component at ∼50 MK are also detected. The value of the hydrogen column density was low, N H ∼ 8 x 10 19 cm -2 , likely due to the clearing of the inner region of the λ Orionis cloud, where HDE 245059 is located. The abundance pattern shows an inverse first ionization potential effect for all elements from O to Fe, the only exception being Ca. To obtain the properties of the binary components, a 3-T model was fitted to the individual zeroth-order spectra

  19. Dynamics from diffraction

    International Nuclear Information System (INIS)

    Goodwin, Andrew L.; Tucker, Matthew G.; Cope, Elizabeth R.; Dove, Martin T.; Keen, David A.

    2006-01-01

    We explore the possibility that detailed dynamical information might be extracted from powder diffraction data. Our focus is a recently reported technique that employs statistical analysis of atomistic configurations to calculate dynamical properties from neutron total scattering data. We show that it is possible to access the phonon dispersion of low-frequency modes using such an approach, without constraining the results in terms of some pre-defined dynamical model. The high-frequency regions of the phonon spectrum are found to be less well preserved in the diffraction data

  20. Diffractive optical elements as raster-image generators.

    Science.gov (United States)

    Gruber, M

    2001-11-10

    The use of diffractive optical elements (DOEs) to generate complex raster images for a primarily artistic purpose is dealt with. Aspects of human vision that are relevant for the design of such elements are discussed. A design method based on an iterative Fourier transform algorithm and extended with elements from the direct-binary-search and the simulated-annealing algorithms is described. The proposed method provides a large set of parameters that can be adjusted freely to optimize it for any given design task. For demonstration a phase-only DOE was designed that generates an image of a Chinese dragon as a diffraction pattern. It was realized as a surface-relief element on a planar substrate through multilevel binary lithography and reactive-ion etching. Experimental tests confirm the usefulness of the design and the fabrication procedures to achieve excellent image quality.

  1. Four-wave mixing using polarization grating induced thermal grating in liquids exhibiting circular dichroism

    Energy Technology Data Exchange (ETDEWEB)

    Nunes, J.A.; Tong, W.G. [San Diego State Univ., CA (United States). Dept. of Chemistry; Chandler, D.W.; Rahn, L.A. [Sandia National Lab., Livermore, CA (United States). Combustion Research Facility

    1995-04-01

    A novel four-wave mixing technique for the detection of circular dichroism in optically active liquid samples is demonstrated. When two cross-polarized laser beams are crossed at a small angle in a circular dichroic liquid a weak thermal grating is produced with a phase depending on the sign of the circular dichroism. The authors show that the polarization of one of the beams can be modified to allow coherent interference with an intensity-grating induced thermal grating. A probe beam scattering from the composite grating results in a signal that reveals the sign and magnitude of the circular dichroism. The use of this technique to optimize the signal-to-noise ratio in the presence of scattered light and laser intensity noise is discussed.

  2. Parameters for binary TNOs which could be detected by TAOS-II

    Science.gov (United States)

    Castro Chacón, Joel; Reyes-Ruiz, Mauricio; Bosco Hernández-Águila, Joannes; Lehner, Matthew; Hernández, Benjamín; Sanchez, Edilberto; Silva, J. S.; Garcia-Díaz, Teresa; Alcock, Charles; Wang, Shiang-Yu; Chu, You-Hua; Chen, Wen-Ping; Alvarez, Fernando; Figueroa, Liliana; Geary, John C.; Huang, Chung-Kai; Cook, Kem H.; Norton, Timothy; Szentgyorgyi, Andrew; Yen, Wei-Ling; Zhang, Zhi-Wei; TAOS-II

    2017-10-01

    The main goal of the TAOS-II project is to characterize the population of small TNOs by means of detecting serendipitous stellar occultations. The result of an occultation event is a particular feature in the observed light curves resulting from the sampling of the diffraction profile. This diffraction profile contains information about the shape of the occulting object, which can, in principle, also be used to determine if it is a member of a binary system. The combination of physical parameters for binary objects and the capabilities of TAOS-II constrain the properties of the objects that can be detected. In this work we discuss under what conditions and physical parameters, a binary object can be detected by TAOS-II. In order to detect a binary TNO, the following conditions must be met: in first place, the size of the TNO must be big enough to be discriminated in shape and small enough to produce a diffraction pattern that fits into the reading area for just one background star. Secondly, the combination of object size and distance to the Sun have to be such that, diffraction and silhouette contribute to the light curve. The size of a binary object, in terms of detectability, depends on the mass of the system, angular speed and alignment in the moment of detection. Considering these physical parameters and detectability conditions we calculated the corresponding diffraction profiles and compared them with single object profiles. The methodology includes the computation of 2D diffraction patterns by solving the diffraction integral, for possible binary TNOs.

  3. Toward compact millimeter-wave diode in thin stacked-hole array assisted by a dielectric grating

    Science.gov (United States)

    Beruete, M.; Serebryannikov, A. E.; Torres, V.; Navarro-Cía, M.; Sorolla, M.

    2011-10-01

    Unidirectional transmission in thin stacked hole arrays (SHAs), whose spatial inversion symmetry is broken by adding a dielectric grating at one of the interfaces, is theoretically predicted and experimentally validated in the millimeter-wave regime. It appears at a fixed nonzero angle of incidence due to hybridization of SHA resonances with diffraction effects. In contrast to the earlier suggested structures with the diffraction relevant unidirectional transmission mechanism, the nonsymmetric diode-like structure founded on the intrinsically subwavelength SHA, which supports left-handed propagation, is less than one wavelength thick.

  4. Diffractive processes in nuclear physics

    International Nuclear Information System (INIS)

    Frahn, W.E.

    1985-01-01

    The book reviews diffraction scattering in nuclear physics. The first part concerns nuclear diffraction models, and includes the basic concepts and theory of diffraction scattering, as well as diffraction in configuration space and in angular momentum space. The second part deals with closed formalism for strong absorption processes including: elastic scattering, inelastic scattering, transfer reactions and coupled-channel extensions. (U.K.)

  5. Numerical analysis of the harmonic components of the Bragg wavelength content in spectral responses of apodized fiber Bragg gratings written by means of a phase mask with a variable phase step height.

    Science.gov (United States)

    Osuch, Tomasz

    2016-02-01

    The influence of the complex interference patterns created by a phase mask with variable diffraction efficiency in apodized fiber Bragg grating (FBGs) formation on their reflectance spectra is studied. The effect of the significant contributions of the zeroth and higher (m>±1) diffraction orders on the Bragg wavelength peak and its harmonic components is analyzed numerically. The results obtained for Gaussian and tanh apodization profiles are compared with similar data calculated for a uniform grating. It is demonstrated that when an apodized FBG is written using a phase mask with variable diffraction efficiency, significant enhancement of the harmonic components and a reduction of the Bragg wavelength peak in the grating spectral response are observed. This is particularly noticeable for the Gaussian apodization profile due to the substantial contributions of phase mask sections with relatively small phase steps in the FBG formation.

  6. Hybrid grating reflectors: Origin of ultrabroad stopband

    Energy Technology Data Exchange (ETDEWEB)

    Park, Gyeong Cheol; Taghizadeh, Alireza; Chung, Il-Sug, E-mail: ilch@fotonik.dtu.dk [DTU Fotonik, Department of Photonics Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark)

    2016-04-04

    Hybrid grating (HG) reflectors with a high-refractive-index cap layer added onto a high contrast grating (HCG) provide a high reflectance close to 100% over a broader wavelength range than HCGs. The combination of a cap layer and a grating layer brings a strong Fabry-Perot (FP) resonance as well as a weak guided mode (GM) resonance. Most of the reflected power results from the FP resonance, while the GM resonance plays a key role in achieving a reflectance close to 100% as well as broadening the stopband. An HG sample with 7 InGaAlAs quantum wells included in the cap layer has been fabricated by directly wafer-bonding a III-V cap layer onto a Si grating layer. Its reflection property has been characterized. This heterogeneously integrated HG reflector may allow for a hybrid III-V on Si laser to be thermally efficient, which has promising prospects for silicon photonics light sources and high-speed operation.

  7. Large-aperture subwavelength grating couplers.

    Science.gov (United States)

    Qi, Fan; Ma, Qingyan; Wang, Yufei; Zheng, Wanhua

    2016-04-10

    Subwavelength nanostructure grating couplers fabricated on silicon-on-insulator substrates are used to simplify the fabrication process while maintaining high coupling efficiency. The main obstacle for their application in photonic integrated circuits is the small aperture size of the nanostructure when TE polarization is involved, since they are difficult to achieve with 193 nm deep-ultraviolet lithography and cause problems in inductively coupled plasma etching. A larger lateral period has been used to increase the aperture size. Here, we propose that decreasing the effective index of the nanostructure can also enlarge the aperture size. We analyze the two methods in detail with a rectangle-hole nanostructure and 220 nm thick waveguide layer, aiming at TE polarization centered at 1560 nm. We find performance degenerations for large lateral periods, and this can be simply compensated by adjusting the width of the rectangle hole. The minimum linewidth of the nanostructure can reach 240 nm, while the coupling efficiency is just slightly decreased. The backreflections of a large-aperture grating increase but stay in the same order with ordinary ones, and we also show that this can be overcome by apodizing the grating structure. Finally, we experimentally demonstrate the designed large-aperture grating couplers and the coupling efficiencies are higher than 35%, and reach a rectangle-hole width.

  8. Smart photogalvanic running-grating interferometer

    DEFF Research Database (Denmark)

    Kukhtarev, N. V.; Kukhtareva, T.; Edwards, M. E.

    2005-01-01

    Photogalvanic effect produces actuation of periodic motion of macroscopic LiNbO3 crystal. This effect was applied to the development of an all-optical moving-grating interferometer usable for optical trapping and transport of algae chlorella microorganisms diluted in water with a concentration...

  9. 130-nm tunable grating-mirror VCSEL

    DEFF Research Database (Denmark)

    Chung, Il-Sug; Mørk, Jesper

    2014-01-01

    We have reported that a combination of the high-index-contrast grating (HCG) mirror as movable mirror and the extended cavity configuration with an antireflection layer can provide a tuning wavelength range of 100 nm for tunable VCSELs. Here, we report that using the air-coupled cavity...

  10. Surface Fluctuation Scattering using Grating Heterodyne Spectroscopy

    DEFF Research Database (Denmark)

    Edwards, R. V.; Sirohi, R. S.; Mann, J. A.

    1982-01-01

    Heterodyne photon spectroscopy is used for the study of the viscoelastic properties of the liquid interface by studying light scattered from thermally generated surface fluctuations. A theory of a heterodyne apparatus based on a grating is presented, and the heterodyne condition is given in terms...

  11. Diffusion of solid fuelon a vibrating grate

    DEFF Research Database (Denmark)

    Sabelström, Hanna Katarina

    to introduce a varying velocity depending on the position on the grate, a modification of the model is necessary where also the density will vary as a consequence of the continuity equation. The definition of the density will thereby change from being the particle density to be the cell density, i.e. a measure...

  12. Fibre Bragg Grating and Long Period Grating Sensors in Polymer Optical Fibres

    OpenAIRE

    Bundalo, Ivan-Lazar; Bang, Ole; Nielsen, Kristian

    2017-01-01

    The work presented in this thesis focuses on improving the fabrication of Fibre Bragg Gratings (FBGs) and Long Period Gratings (LPGs) in microstructure polymer optical fibres (mPOF). It also focuses on exploring new options for biomedical and acoustic sensing with the purpose of expanding the range of applications and pushing the limits. The first part of the work focuses on the fabrication of FBGs in polymer optical fibres. FBGs are a periodic perturbation of the refractive index of the opti...

  13. Diffraction at collider energies

    International Nuclear Information System (INIS)

    Frankfurt, L.L.

    1992-01-01

    Lessons with ''soft'' hadron physics to explain (a) feasibility to observe and to investigate color transparency, color opacity effects at colliders; (b) significant probability and specific features of hard diffractive processes; (c) feasibility to investigate components of parton wave functions of hadrons with minimal number of constituents. This new physics would be more important with increase of collision energy

  14. Diffraction through partial identity

    International Nuclear Information System (INIS)

    Blum, W.

    1981-06-01

    A model of diffraction dissociation is proposed in which the quantum-mechanical interference between the incoming and the outgoing wave determines the cross-section. This interference occurs due to the finite life-time of the excited state. (orig.)

  15. Measurement of electron-spin transports in GaAs quantum wells using a transmission-grating-sampled circular dichroism absorption spectroscopy

    International Nuclear Information System (INIS)

    Yu, Hua-Liang; Fang, Shaoyin; Wen, Jinhui; Lai, Tianshu

    2014-01-01

    A transmission-grating-sampled circular dichroism absorption spectroscopy (TGS-CDAS) and its theoretical model are developed sensitively to measure decay dynamics of a transient spin grating (TSG). A binary transmission grating with the same period as TSG is set behind TSG. It allows only a same small part of each period in TSG measured by circular dichroism absorption effect of a probe. In this way, the zero average of spin-dependent effects measured over a whole period in TSG is avoided so that TGS-CDAS has a high sensitivity to spin evolution in TSG. Spin transport experiments are performed on GaAs/AlGaAs quantum wells. Experimental results prove the feasibility and reliability of TGS-CDAS

  16. Investigating the interaction of x-ray free electron laser radiation with grating structure

    Czech Academy of Sciences Publication Activity Database

    Gaudin, J.; Ozkan, C.; Chalupský, Jaromír; Bajt, S.; Burian, Tomáš; Vyšín, Luděk; Coppola, N.; Dastjani-Farahani, S.; Chapman, H.N.; Galasso, G.; Hájková, Věra; Harmand, M.; Juha, Libor; Jurek, M.; Loch, R.A.; Möller, S.; Nagasono, M.; Störmer, M.; Sinn, H.; Saksl, K.; Sobierajski, R.; Schulz, J.; Sovak, P.; Toleikis, S.; Tiedtke, K.; Tschentscher, T.; Krzywinski, J.

    2012-01-01

    Roč. 37, č. 15 (2012), s. 3033-3035 ISSN 0146-9592 R&D Projects: GA ČR(CZ) GAP108/11/1312; GA ČR GAP205/11/0571; GA ČR GAP208/10/2302; GA MŠk LA08024; GA MŠk(CZ) ME10046 Institutional research plan: CEZ:AV0Z10100523 Keywords : radiation damage * diffraction grating * amorphous carbon * soft x-rays * free-electron laser Subject RIV: BH - Optics , Masers, Lasers Impact factor: 3.385, year: 2012

  17. Compressing Binary Decision Diagrams

    DEFF Research Database (Denmark)

    Hansen, Esben Rune; Satti, Srinivasa Rao; Tiedemann, Peter

    2008-01-01

    The paper introduces a new technique for compressing Binary Decision Diagrams in those cases where random access is not required. Using this technique, compression and decompression can be done in linear time in the size of the BDD and compression will in many cases reduce the size of the BDD to ......-2 bits per node. Empirical results for our compression technique are presented, including comparisons with previously introduced techniques, showing that the new technique dominate on all tested instances......The paper introduces a new technique for compressing Binary Decision Diagrams in those cases where random access is not required. Using this technique, compression and decompression can be done in linear time in the size of the BDD and compression will in many cases reduce the size of the BDD to 1...

  18. Compressing Binary Decision Diagrams

    DEFF Research Database (Denmark)

    Rune Hansen, Esben; Srinivasa Rao, S.; Tiedemann, Peter

    The paper introduces a new technique for compressing Binary Decision Diagrams in those cases where random access is not required. Using this technique, compression and decompression can be done in linear time in the size of the BDD and compression will in many cases reduce the size of the BDD to ......-2 bits per node. Empirical results for our compression technique are presented, including comparisons with previously introduced techniques, showing that the new technique dominate on all tested instances.......The paper introduces a new technique for compressing Binary Decision Diagrams in those cases where random access is not required. Using this technique, compression and decompression can be done in linear time in the size of the BDD and compression will in many cases reduce the size of the BDD to 1...

  19. Development of a segmented grating mount system for FIREX-1

    International Nuclear Information System (INIS)

    Ezaki, Y; Tabata, M; Kihara, M; Horiuchi, Y; Endo, M; Jitsuno, T

    2008-01-01

    A mount system for segmented meter-sized gratings has been developed, which has a high precision grating support mechanism and drive mechanism to minimize both deformation of the optical surfaces and misalignments in setting a segmented grating for obtaining sufficient performance of the pulse compressor. From analytical calculations, deformation of the grating surface is less than 1/20 lambda RMS and the estimated drive resolution for piston and tilt drive of the segmented grating is 1/20 lambda, which are both compliant with the requirements for the rear-end subsystem of FIREX-1

  20. Fundamental limit of light trapping in grating structures

    KAUST Repository

    Yu, Zongfu

    2010-08-11

    We use a rigorous electromagnetic approach to analyze the fundamental limit of light-trapping enhancement in grating structures. This limit can exceed the bulk limit of 4n 2, but has significant angular dependency. We explicitly show that 2D gratings provide more enhancement than 1D gratings. We also show the effects of the grating profile’s symmetry on the absorption enhancement limit. Numerical simulations are applied to support the theory. Our findings provide general guidance for the design of grating structures for light-trapping solar cells.

  1. CHANDRA HIGH-ENERGY TRANSMISSION GRATING SPECTRUM OF AE AQUARII

    International Nuclear Information System (INIS)

    Mauche, Christopher W.

    2009-01-01

    The nova-like cataclysmic binary AE Aqr, which is currently understood to be a former supersoft X-ray binary and current magnetic propeller, was observed for over two binary orbits (78 ks) in 2005 August with the High-Energy Transmission Grating (HETG) on board the Chandra X-ray Observatory. The long, uninterrupted Chandra observation provides a wealth of details concerning the X-ray emission of AE Aqr, many of which are new and unique to the HETG. First, the X-ray spectrum is that of an optically thin multi-temperature thermal plasma; the X-ray emission lines are broad, with widths that increase with the line energy from σ ∼ 1 eV (510 km s -1 ) for O VIII to σ ∼ 5.5 eV (820 km s -1 ) for Si XIV; the X-ray spectrum is reasonably well fit by a plasma model with a Gaussian emission measure distribution that peaks at log T(K) = 7.16, has a width σ = 0.48, an Fe abundance equal to 0.44 times solar, and other metal (primarily Ne, Mg, and Si) abundances equal to 0.76 times solar; and for a distance d = 100 pc, the total emission measure EM = 8.0 x 10 53 cm -3 and the 0.5-10 keV luminosity L X = 1.1 x 10 31 erg s -1 . Second, based on the f/(i + r) flux ratios of the forbidden (f), intercombination (i), and recombination (r) lines of the Heα triplets of N VI, O VII, and Ne IX measured by Itoh et al. in the XMM-Newton Reflection Grating Spectrometer spectrum and those of O VII, Ne IX, Mg XI, and Si XIII in the Chandra HETG spectrum, either the electron density of the plasma increases with temperature by over three orders of magnitude, from n e ∼ 6 x 10 10 cm -3 for N VI [log T(K) ∼ 6] to n e ∼ 1 x 10 14 cm -3 for Si XIII [log T(K) ∼ 7], and/or the plasma is significantly affected by photoexcitation. Third, the radial velocity of the X-ray emission lines varies on the white dwarf spin phase, with two oscillations per spin cycle and an amplitude K ∼ 160 km s -1 . These results appear to be inconsistent with the recent models of Itoh et al., Ikhsanov, and

  2. Parametric binary dissection

    Science.gov (United States)

    Bokhari, Shahid H.; Crockett, Thomas W.; Nicol, David M.

    1993-01-01

    Binary dissection is widely used to partition non-uniform domains over parallel computers. This algorithm does not consider the perimeter, surface area, or aspect ratio of the regions being generated and can yield decompositions that have poor communication to computation ratio. Parametric Binary Dissection (PBD) is a new algorithm in which each cut is chosen to minimize load + lambda x(shape). In a 2 (or 3) dimensional problem, load is the amount of computation to be performed in a subregion and shape could refer to the perimeter (respectively surface) of that subregion. Shape is a measure of communication overhead and the parameter permits us to trade off load imbalance against communication overhead. When A is zero, the algorithm reduces to plain binary dissection. This algorithm can be used to partition graphs embedded in 2 or 3-d. Load is the number of nodes in a subregion, shape the number of edges that leave that subregion, and lambda the ratio of time to communicate over an edge to the time to compute at a node. An algorithm is presented that finds the depth d parametric dissection of an embedded graph with n vertices and e edges in O(max(n log n, de)) time, which is an improvement over the O(dn log n) time of plain binary dissection. Parallel versions of this algorithm are also presented; the best of these requires O((n/p) log(sup 3)p) time on a p processor hypercube, assuming graphs of bounded degree. How PBD is applied to 3-d unstructured meshes and yields partitions that are better than those obtained by plain dissection is described. Its application to the color image quantization problem is also discussed, in which samples in a high-resolution color space are mapped onto a lower resolution space in a way that minimizes the color error.

  3. Binary Masking & Speech Intelligibility

    OpenAIRE

    Boldt, Jesper

    2010-01-01

    The purpose of this thesis is to examine how binary masking can be used to increase intelligibility in situations where hearing impaired listeners have difficulties understanding what is being said. The major part of the experiments carried out in this thesis can be categorized as either experiments under ideal conditions or as experiments under more realistic conditions useful for real-life applications such as hearing aids. In the experiments under ideal conditions, the previously defined i...

  4. Rheology of ABS and binary of organo clay nanocomposites

    International Nuclear Information System (INIS)

    Galvan, Danieli; Mazzucco, Mateus; Carneiro, Fabio; Bartoli, Julio R.; Morales, Ana Rita; D'Avila, Marcos A.

    2011-01-01

    nanocomposites of poly(acrylonitrile-butadiene-styrene) and organically modified montmorillonite clays by melt intercalation on a co-rotating twin-screw extruder were prepared and characterized. It was studied the effects of screw torque and a binary mixture of organically modified montmorillonites on the intercalation/exfoliation of organoclays in the polymer matrix, characterized by X-ray diffraction morphological analyses and by capillary and parallel plates rheological analyses. (author)

  5. Fabrication of large area plasmonic nanoparticle grating structure on silver halide based transmission electron microscope film and its application as a surface enhanced Raman spectroscopy substrate

    Energy Technology Data Exchange (ETDEWEB)

    Sudheer,, E-mail: sudheer@rrcat.gov.in; Tiwari, P.; Singh, M. N.; Sinha, A. K.; Rai, V. N.; Srivastava, A. K. [Indus Synchrotrons Utilization Division, Raja Ramanna Centre for Advanced Technology Indore, Madhya Pradesh 452013 (India); Bhartiya, S. [Laser Material Development and Device Division, Raja Ramanna Centre for Advanced Technology Indore, Madhya Pradesh 452013 (India); Mukherjee, C. [Mechanical and Optical Support Section, Raja Ramanna Centre for Advanced Technology Indore, Madhya Pradesh 452013 (India)

    2015-08-14

    The plasmonic responses of silver nanoparticle grating structures of different periods made on silver halide based electron microscope film are investigated. Raster scan of the conventional scanning electron microscope (SEM) is used to carry out electron beam lithography for fabricating the plasmonic nanoparticle grating (PNG) structures. Morphological characterization of the PNG structures, carried out by the SEM and the atomic force microscope, indicates that the depth of the groove decreases with a decrease in the grating period. Elemental characterization performed by the energy dispersive spectroscopy and the x-ray diffraction shows the presence of nanoparticles of silver in the PNG grating. The optical characterization of the gratings shows that the localized surface plasmon resonance peak shifts from 366 to 378 nm and broadens with a decrease in grating period from 10 to 2.5 μm. The surface enhanced Raman spectroscopy of the Rhodamine-6G dye coated PNG structure shows the maximum enhancement by two orders of magnitude in comparison to the randomly distributed silver nanoparticles having similar size and shape as the PNG structure.

  6. Fabrication of large area plasmonic nanoparticle grating structure on silver halide based transmission electron microscope film and its application as a surface enhanced Raman spectroscopy substrate

    International Nuclear Information System (INIS)

    Sudheer,; Tiwari, P.; Singh, M. N.; Sinha, A. K.; Rai, V. N.; Srivastava, A. K.; Bhartiya, S.; Mukherjee, C.

    2015-01-01

    The plasmonic responses of silver nanoparticle grating structures of different periods made on silver halide based electron microscope film are investigated. Raster scan of the conventional scanning electron microscope (SEM) is used to carry out electron beam lithography for fabricating the plasmonic nanoparticle grating (PNG) structures. Morphological characterization of the PNG structures, carried out by the SEM and the atomic force microscope, indicates that the depth of the groove decreases with a decrease in the grating period. Elemental characterization performed by the energy dispersive spectroscopy and the x-ray diffraction shows the presence of nanoparticles of silver in the PNG grating. The optical characterization of the gratings shows that the localized surface plasmon resonance peak shifts from 366 to 378 nm and broadens with a decrease in grating period from 10 to 2.5 μm. The surface enhanced Raman spectroscopy of the Rhodamine-6G dye coated PNG structure shows the maximum enhancement by two orders of magnitude in comparison to the randomly distributed silver nanoparticles having similar size and shape as the PNG structure

  7. Contribution to diffraction theory

    International Nuclear Information System (INIS)

    Chako, N.

    1966-11-01

    In a first part, we have given a general and detailed treatment of the modern theory of diffraction. The rigorous theory is formulated as a boundary value problem of the wave equation or Maxwell equations. However, up to the present time, such a program of treating diffraction by optical systems, even for simple optical instruments, has not been realized due to the complicated character of the boundary conditions. The recent developments show clearly the nature of the approximation of the classical theories originally due to Fresnel and Young, later formulated in a rigorous manner by Kirchhoff and Rubinowicz, respectively and, at the same time the insufficiency of these theories in explaining a number of diffraction phenomena. Furthermore, we have made a study of the limitations of the approximate theories and the recent attempts to improve these. The second part is devoted to a general mathematical treatment of the theory of diffraction of optical systems including aberrations. After a general and specific analysis of geometrical and wave aberrations along classical and modern (Nijboer) lines, we have been able to evaluate the diffraction integrals representing the image field at any point in image space explicitly, when the aberrations are small. Our formulas are the generalisations of all anterior results obtained by previous investigators. Moreover, we have discussed the Zernike-Nijboer theory of aberration and generalised it not only for rotational systems, but also for non-symmetric systems as well, including the case of non circular apertures. The extension to non-circular apertures is done by introducing orthogonal functions or polynomials over such aperture shapes. So far the results are valid for small aberrations, that is to say, where the deformation of the real wave front emerging from the optical system is less than a wave length of light or of the electromagnetic wave from the ideal wave front. If the aberrations are large, then one must employ the

  8. Massive Black Hole Binary Evolution

    Directory of Open Access Journals (Sweden)

    Merritt David

    2005-11-01

    Full Text Available Coalescence of binary supermassive black holes (SBHs would constitute the strongest sources of gravitational waves to be observed by LISA. While the formation of binary SBHs during galaxy mergers is almost inevitable, coalescence requires that the separation between binary components first drop by a few orders of magnitude, due presumably to interaction of the binary with stars and gas in a galactic nucleus. This article reviews the observational evidence for binary SBHs and discusses how they would evolve. No completely convincing case of a bound, binary SBH has yet been found, although a handful of systems (e.g. interacting galaxies; remnants of galaxy mergers are now believed to contain two SBHs at projected separations of <~ 1kpc. N-body studies of binary evolution in gas-free galaxies have reached large enough particle numbers to reproduce the slow, “diffusive” refilling of the binary’s loss cone that is believed to characterize binary evolution in real galactic nuclei. While some of the results of these simulations - e.g. the binary hardening rate and eccentricity evolution - are strongly N-dependent, others - e.g. the “damage” inflicted by the binary on the nucleus - are not. Luminous early-type galaxies often exhibit depleted cores with masses of ~ 1-2 times the mass of their nuclear SBHs, consistent with the predictions of the binary model. Studies of the interaction of massive binaries with gas are still in their infancy, although much progress is expected in the near future. Binary coalescence has a large influence on the spins of SBHs, even for mass ratios as extreme as 10:1, and evidence of spin-flips may have been observed.

  9. Central Diffraction at ALICE

    CERN Document Server

    Lämsä, Jerry W

    2011-01-01

    The ALICE experiment is shown to be well suited for studies of exclusive final states from central diffractive reactions. The gluon-rich environment of the central system allows detailed QCD studies and searches for exotic meson states, such as glueballs, hybrids and new charmonium-like states. It would also provide a good testing ground for detailed studies of heavy quarkonia. Due to its central barrel performance, ALICE can accurately measure the low-mass central systems with good purity. The efficiency of the Forward Multiplicity Detector (FMD) and the Forward Shower Counter (FSC) system for detecting rapidity gaps is shown to be adequate for the proposed studies. With this detector arrangement, valuable new data can be obtained by tagging central diffractive processes.

  10. Diffraction Studies of Multiferroics

    Science.gov (United States)

    Johnson, Roger D.; Radaelli, Paolo G.

    2014-07-01

    In multiferroics, magnetism is coupled to ferroelectricity so that the configuration of magnetic moments may be modified by an external electric field and, conversely, the electrically polar state may be magnetically switched. Such functionality has the potential for new technology such as energy-efficient, electrically written magnetic memories. Furthermore, multiferroics are of interest in fundamental research into quantum matter. Understanding the interplay between magnetism and ferroelectricity has posed a significant challenge to the scientific community. State-of-the-art diffraction experiments have played a unique role, as they are sensitive to both magnetic ordering and the atomic displacements associated with ferroelectricity. Exceptional insights have been gained from neutron polarimetry techniques complemented by X-ray magnetic scattering experiments, which, for the first time, have been applied to a large selection of related materials and problems. In this review, we discuss a broad selection of multiferroics and the diffraction experiments used to explain their phenomenology.

  11. Mid-wave infrared beam steering based on high-efficiency liquid crystal diffractive waveplates.

    Science.gov (United States)

    Gou, Fangwang; Peng, Fenglin; Ru, Qitian; Lee, Yun-Han; Chen, Haiwei; He, Ziqian; Zhan, Tao; Vodopyanov, Konstantin L; Wu, Shin-Tson

    2017-09-18

    We demonstrated two liquid crystal diffractive waveplates: one optimized for near-infrared (1.06 µm), and another for mid-wave infrared (MWIR, 3~5 µm). By employing a low loss liquid crystal mixture UCF-M3, whose absorption loss is below 2% in the 4~5 µm spectral region, the grating achieves over 98% diffraction efficiency in a broad MWIR range. To switch the grating, both active and passive driving methods can be considered. In our experiment, we used a polymer-stabilized twisted nematic cell as the polarization rotator for passive driving. The obtained rise time is 0.2 ms and decay time is 10 ms.

  12. Spectral and Diffraction Tomography

    OpenAIRE

    Lionheart, William

    2016-01-01

    We discuss several cases of what we call "Rich Tomography" problems in which more data is measured than a scalar for each ray. We give examples of infra red spectral tomography and Bragg edge neutron tomography in which the data is insufficient. For diffraction tomography of strain for polycrystaline materials we give an explicit reconstruction procedure. We go on to describe a way to find six independent rotation axes using Pascal's theorem of projective geometry

  13. Dynamical theory of diffraction

    International Nuclear Information System (INIS)

    Dederichs, P.H.

    1978-01-01

    The paper is concerned with 1. the limits of the kinematical theory 2. basic equations for diffraction 3. Bloch waves 4. band structure and dispersion surfaces of free electrons 5. Weak potential: The two-beam case 6. a modification for X-ray scattering 7. absorption mechanisms and Bormann effect 8. k-selection and boundary conditions 9. the symmetrical laue case 10. the symmetrical Bragg case. (orig.) [de

  14. X-ray diffraction

    International Nuclear Information System (INIS)

    Einstein, J.R.; Wei, C.H.

    1982-01-01

    We have been interested in structural elucidation by x-ray diffraction of compounds of biological interest. Understanding exactly how atoms are arranged in three-dimensional arrays as molecules can help explain the relationship between structure and functions. The species investigated may vary in size and shape; our recent studies included such diverse substances as antischistosomal drugs, a complex of cadmium with nucleic acid base, nitrate salts of adenine, and proteins

  15. Polychromatic diffraction contrast tomography

    International Nuclear Information System (INIS)

    King, A.; Reischig, P.; Adrien, J.; Peetermans, S.; Ludwig, W.

    2014-01-01

    This tutorial review introduces the use of polychromatic radiation for 3D grain mapping using X-ray diffraction contrast tomography. The objective is to produce a 3D map of the grain shapes and orientations within a bulk, millimeter-sized polycrystalline sample. The use of polychromatic radiation enables the standard synchrotron X-ray technique to be applied in a wider range of contexts: 1) Using laboratory X-ray sources allows a much wider application of the diffraction contrast tomography technique. 2) Neutron sources allow large samples, or samples containing high Z elements to be studied. 3) Applied to synchrotron sources, smaller samples may be treated, or faster measurements may be possible. Challenges and particularities in the data acquisition and processing, and the limitations of the different variants, are discussed. - Highlights: • We present a tutorial review of polychromatic diffraction contrast tomography techniques. • The use of polychromatic radiation allows the standard synchrotron DCT technique to be extended to a range of other sources. • The characteristics and limitations of all variants of the techniques are derived, discussed and compared. • Examples using laboratory X-ray and cold neutron radiation are presented. • Suggestions for the future development of these techniques are presented

  16. Toward multi-Gbps indoor optical wireless multicasting system employing passive diffractive optics.

    Science.gov (United States)

    Oh, C W; Huijskens, F M; Cao, Z; Tangdiongga, E; Koonen, A M J

    2014-05-01

    This Letter presents the evaluation and demonstration of an optical free-space (FS) multicasting system for multi-Gigabits-per-second (multi-Gbps) indoor transmission. These simultaneous line-of-sight links are formed by infrared beams and are beam-steered using a passive diffraction grating. The experiment has resulted in error-free links (bit error rate optical wireless communication and can be seamlessly integrated in in-building fiber networks.

  17. Stable algorithm for the computation of the electromagnetic field distribution of eigenmodes of periodic diffraction structures.

    Science.gov (United States)

    Bezus, Evgeni A; Doskolovich, Leonid L

    2012-11-01

    In the present work, a stable algorithm for the calculation of the electromagnetic field distributions of the eigenmodes of one-dimensional diffraction gratings is presented. The proposed approach is based on the method for the computation of the propagation constants of Bloch waves of such structures previously presented by Cao et al.[J. Opt. Soc. Am. A 19, 335 (2002)] and uses a modified S-matrix algorithm to ensure numerical stability.

  18. Active resonant subwavelength grating for scannerless range imaging sensors.

    Energy Technology Data Exchange (ETDEWEB)

    Kemme, Shanalyn A.; Nellums, Robert O.; Boye, Robert R.; Peters, David William

    2006-11-01

    In this late-start LDRD, we will present a design for a wavelength-agile, high-speed modulator that enables a long-term vision for the THz Scannerless Range Imaging (SRI) sensor. It takes the place of the currently-utilized SRI micro-channel plate which is limited to photocathode sensitive wavelengths (primarily in the visible and near-IR regimes). Two of Sandia's successful technologies--subwavelength diffractive optics and THz sources and detectors--are poised to extend the capabilities of the SRI sensor. The goal is to drastically broaden the SRI's sensing waveband--all the way to the THz regime--so the sensor can see through image-obscuring, scattering environments like smoke and dust. Surface properties, such as reflectivity, emissivity, and scattering roughness, vary greatly with the illuminating wavelength. Thus, objects that are difficult to image at the SRI sensor's present near-IR wavelengths may be imaged more easily at the considerably longer THz wavelengths (0.1 to 1mm). The proposed component is an active Resonant Subwavelength Grating (RSG). Sandia invested considerable effort on a passive RSG two years ago, which resulted in a highly-efficient (reflectivity greater than gold), wavelength-specific reflector. For this late-start LDRD proposal, we will transform the passive RSG design into an active laser-line reflector.

  19. Metallic Strip Gratings in the Sub-Subwavelength Regime

    Directory of Open Access Journals (Sweden)

    Adriana Savin

    2014-07-01

    Full Text Available Metallic strip gratings (MSG have different applications, ranging from printed circuits to filters in microwave domains. When they are under the influence of an electromagnetic field, evanescent and/or abnormal modes appear in the region between the traces, their utilization leading to the development of new electromagnetic nondestructive evaluation methods. This paper studies the behavior of MSGs in the sub-subwavelength regime when they are excited with TEz or TMz polarized plane waves and the slits are filled with different dielectrics. The appearance of propagating, evanescent and abnormal modes is emphasized using an electromagnetic sensor with metamaterials lens realized with two conical Swiss rolls, which allows the extraction of the information carried by the guided evanescent waves. The evanescent waves, manipulated by the electromagnetic sensor with metamaterial lenses, improve the electromagnetic images so that a better spatial resolution is obtained, exceeding the limit imposed by diffraction. Their theoretical and experimental confirmation opens the perspective for development of new types of sensors working in radio and microwave frequencies.

  20. Theory of Fiber Optical Bragg Grating: Revisited

    Science.gov (United States)

    Tai, H.

    2003-01-01

    The reflected signature of an optical fiber Bragg grating is analyzed using the transfer function method. This approach is capable to cast all relevant quantities into proper places and provides a better physical understanding. The relationship between reflected signal, number of periods, index of refraction, and reflected wave phase is elucidated. The condition for which the maximum reflectivity is achieved is fully examined. We also have derived an expression to predict the reflectivity minima accurately when the reflected wave is detuned. Furthermore, using the segmented potential approach, this model can handle arbitrary index of refraction profiles and compare the strength of optical reflectivity of different profiles. The condition of a non-uniform grating is also addressed.

  1. Response of fiber Bragg gratings to longitudinal ultrasonic waves.

    Science.gov (United States)

    Minardo, Aldo; Cusano, Andrea; Bernini, Romeo; Zeni, Luigi; Giordano, Michele

    2005-02-01

    In the last years, fiber optic sensors have been widely exploited for several sensing applications, including static and dynamic strain measurements up to acoustic detection. Among these, fiber Bragg grating sensors have been indicated as the ideal candidate for practical structural health monitoring in light of their unique advantages over conventional sensing devices. Although this class of sensors has been successfully tested for static and low-frequency measurements, the identification of sensor performances for high-frequency detection, including acoustic emission and ultrasonic investigations, is required. To this aim, the analysis of feasibilty on the use of fiber Bragg grating sensors as ultrasonic detectors has been carried out. In particular, the response of fiber Bragg gratings subjected to the longitudinal ultrasonic (US) field has been theoretically and numerically investigated. Ultrasonic field interaction has been modeled, taking into account the direct deformation of the grating pitch combined with changes in local refractive index due to the elasto-optic effect. Numerical results, obtained for both uniform and Gaussian-apodized fiber Bragg gratings, show that the grating spectrum is strongly influenced by the US field in terms of shape and central wavelength. In particular, a key parameter affecting the grating response is the ratio between the US wavelength and the grating length. Normal operation characterized by changes in wavelength of undistorted Bragg peak is possible only for US wavelengths longer than the grating length. For US wavelengths approaching the grating length, the wavelength change is accompanied by subpeaks formation and main peak amplitude modulation. This effect can be attributed to the nonuniformity of the US perturbation along the grating length. At very high US frequencies, the grating is not sensitive any longer. The results of this analysis provide useful tools for the design of grating-based ultrasound sensors for

  2. Hybrid grating-prism dispersion eraser

    Science.gov (United States)

    Wang, Cheng; Li, Shuai; Liu, Yanqi; Liu, Xingyan; Leng, Yuxin; Li, Ruxin

    2018-03-01

    A hybrid grating-prism dispersion eraser is proposed to achieve broadband dispersion compensation. A ray-tracing model is built up for its phase spectrum and derivatives. The numerical calculation shows that the eraser can compensate dispersion up to fourth-order. When it is used in chirped-pulse amplifiers, it can obtain aberration-free phase with above 120 nm bandwidth at 0 . 8 μm central wavelength and support near-Fourier-transform-limited femtosecond pulses output.

  3. Robust topology design of periodic grating surfaces

    DEFF Research Database (Denmark)

    Friis, Kasper Storgaard; Sigmund, Ole

    2012-01-01

    Modern nanoscale manufacturing techniques allow for a high degree of flexibility in designing surface microstructures and nanostructures. Injection molding of nanosized features allows for mass production of plastic components with a tailored nanostructure producing specific optical effects...... depending on the purpose. This work details the use of topology optimization for designing periodic polymer grating surfaces with complex optical properties. A method based on robust topology optimization is formulated for designing the nanostructure of plastic surfaces with extreme reflection...

  4. High-index-contrast subwavelength grating VCSEL

    Science.gov (United States)

    Gilet, Philippe; Olivier, Nicolas; Grosse, Philippe; Gilbert, Karen; Chelnokov, Alexei; Chung, Il-Sug; Mørk, Jesper

    2010-02-01

    In this article, we report our results on 980nm high-index-contrast subwavelength grating (HCG) VCSELs for optical interconnection applications. In our structure, a thin undoped HCG layer replaces a thick p-type Bragg mirror. The HCG mirror can feasibly achieve polarization-selective reflectivities close to 100%. The investigated structure consists of a HCG mirror with an underneath λ/4-thick oxide gap, four p-type GaAlAs/GaAs pairs for current spreading, three InGaAs/GaAs quantum wells, and an n-type GaAlAs/GaAs Bragg mirror. The HCG structure was defined by e-beam lithography and dry etching. The current oxide aperture and the oxide gap underneath the HCG were simultaneously formed by the selective wet oxidation process. Compared to air-gap high contrast grating mirrors demonstrated elsewhere, our grating mirrors are particular since they are supported by thinner λ/4 aluminium oxide layer, and thus are mechanically robust and thinner than usual designs. Sub-milliamp threshold currents and single-transverse-mode operation was obtained. A hero device exhibited maximum singlemode output power of more than 4 mW at room temperature and 1 mw at 70°C, which are the highest values ever reported from the HCG structures. These results build a bridge between a standard VCSEL and a hybrid laser on silicon, making them of potential use for the realization of silicon photonics.

  5. Grating Spectroscopes and How to Use Them

    CERN Document Server

    Harrison, Ken M

    2012-01-01

    Transmission grating spectroscopes look like simple filters and are designed to screw into place on the eyepiece tube of a telescope for visual use, or into a camera adapter for digicam or CCD imaging. They are relatively inexpensive and by far the easiest type of astronomical spectroscope to use, and so are the starting point for most beginners. Using the most popular commercially made filter gratings - from Rainbow Optics in the United States to Star Analyser in the United Kingdon - as examples, the book provides all the information needed to set up and use the grating to obtain stellar spectra. It also presents methods of analyzing the results. No heavy mathematics or formulas are involved, although a reasonable level of proficiency in using an astronomic telescope and, if relevant, imaging camera, is assumed. This book contains many practical hints and tips - something that is almost essential to success when starting out. It encourages new users to get quick results, and by following the worked examples,...

  6. Conical diffraction in honeycomb lattices

    International Nuclear Information System (INIS)

    Ablowitz, Mark J.; Nixon, Sean D.; Zhu Yi

    2009-01-01

    Conical diffraction in honeycomb lattices is analyzed. This phenomenon arises in nonlinear Schroedinger equations with honeycomb lattice potentials. In the tight-binding approximation the wave envelope is governed by a nonlinear classical Dirac equation. Numerical simulations show that the Dirac equation and the lattice equation have the same conical diffraction properties. Similar conical diffraction occurs in both the linear and nonlinear regimes. The Dirac system reveals the underlying mechanism for the existence of conical diffraction in honeycomb lattices.

  7. Magnetic binary nanofillers

    Energy Technology Data Exchange (ETDEWEB)

    Morales Mendoza, N. [INQUIMAE, CONICET-UBA, Ciudad Universitaria, Pab2, (C1428EHA) Bs As (Argentina); LPyMC, Dep. De Fisica, FCEN-UBA and IFIBA -CONICET, Ciudad Universitaria, Cap. Fed. (Argentina); Goyanes, S. [LPyMC, Dep. De Fisica, FCEN-UBA and IFIBA -CONICET, Ciudad Universitaria, Cap. Fed. (Argentina); Chiliotte, C.; Bekeris, V. [LBT, Dep. De Fisica, FCEN-UBA. Ciudad Universitaria, Pab1, C1428EGA CABA (Argentina); Rubiolo, G. [LPyMC, Dep. De Fisica, FCEN-UBA and IFIBA -CONICET, Ciudad Universitaria, Cap. Fed. (Argentina); Unidad de Actividad Materiales, CNEA, Av Gral. Paz 1499, San Martin (1650), Prov. de Bs As (Argentina); Candal, R., E-mail: candal@qi.fcen.uba.ar [INQUIMAE, CONICET-UBA, Ciudad Universitaria, Pab2, (C1428EHA) Bs As (Argentina); Escuela de Ciencia y Tecnologia, 3iA, Universidad de Gral. San Martin, San Martin, Prov. Bs As (Argentina)

    2012-08-15

    Magnetic binary nanofillers containing multiwall carbon nanotubes (MWCNT) and hercynite were synthesized by Chemical Vapor Deposition (CVD) on Fe/AlOOH prepared by the sol-gel method. The catalyst precursor was fired at 450 Degree-Sign C, ground and sifted through different meshes. Two powders were obtained with different particle sizes: sample A (50-75 {mu}m) and sample B (smaller than 50 {mu}m). These powders are composed of iron oxide particles widely dispersed in the non-crystalline matrix of aluminum oxide and they are not ferromagnetic. After reduction process the powders are composed of {alpha}-Fe nanoparticles inside hercynite matrix. These nanofillers are composed of hercynite containing {alpha}-Fe nanoparticles and MWCNT. The binary magnetic nanofillers were slightly ferromagnetic. The saturation magnetization of the nanofillers depended on the powder particle size. The nanofiller obtained from powder particles in the range 50-75 {mu}m showed a saturation magnetization 36% higher than the one formed from powder particles smaller than 50 {mu}m. The phenomenon is explained in terms of changes in the magnetic environment of the particles as consequence of the presence of MWCNT.

  8. Design of Time-Resolved Shifted Dual Transmission Grating Spectrometer for the X-Ray Spectrum Diagnostics

    Science.gov (United States)

    Wang, Baoqing; Yi, Tao; Wang, Chuanke; Zhu, Xiaoli; Li, Tingshuai; Li, Jin; Liu, Shenye; Jiang, Shaoen; Ding, Yongkun

    2016-07-01

    A new time-resolved shifted dual transmission grating spectrometer (SDTGS) is designed and fabricated in this work. This SDTGS uses a new shifted dual transmission grating (SDTG) as its dispersive component, which has two sub transmission gratings with different line densities, of 2000 lines/mm and 5000 lines/mm. The axes of the two sub transmission gratings in SDTG are horizontally and vertically shifted a certain distance to measure a broad range of 0.1-5 keV time-resolved X-ray spectra. The SDTG has been calibrated with a soft X-ray beam of the synchrotron radiation facility and its diffraction efficiency is also measured. The designed SDTGS can take full use of the space on a record panel and improve the precision for measuring spatial and temporal spectrum simultaneously. It will be a promising application for accurate diagnosis of the soft X-ray spectrum in inertial confinement fusion. supported by National Natural Science Foundation of China (Nos. 11405158 and 11435011) and Development Foundation of China Academy of Engineering Physics (Nos. 2014B0102011 and 2014B0102012)

  9. Design and fabrication of a spatial light modulator using thermally tunable grating and a thin-film heater.

    Science.gov (United States)

    Riahi, Mohammadreza; Latifi, Hamid; Madani, Abbas; Moazzenzadeh, Ali

    2009-10-20

    We propose the application of a thermally tunable grating as a spatial light modulator. The grooves of a square-well grating are filled with a liquid whose refractive index depends on temperature. The variation of optical characteristics of such a grating with respect to temperature is investigated theoretically and also by simulation and experiment. A thin-film heater is then used as a heat source. The relation between intensity of the first order of diffraction versus power consumption of the thin-film heater is investigated. Finally, a thin-film heater with a desired pattern is placed at the surface of the grating to fabricate spatial light modulator. By applying electrical current to different elements of the thin-film heater, the fabricated device can project a desired pattern on a screen using a 4f imaging system. The restrictions of such a device are discussed and another structure is proposed and discussed by numerical calculations to increase the ability of the device.

  10. X-ray diffraction

    International Nuclear Information System (INIS)

    Vries, J.L. de.

    1976-01-01

    The seventh edition of Philips' Review of literature on X-ray diffraction begins with a list of conference proceedings on the subject, organised by the Philips' organisation at regular intervals in various European countries. This is followed by a list of bulletins. The bibliography is divided according to the equipment (cameras, diffractometers, monochromators) and its applications. The applications are subdivided into sections for high/low temperature and pressure, effects due to the equipment, small angle scattering and a part for stress, texture and phase analyses of metals and quantitative analysis of minerals

  11. Theoretical Investigation of Subwavelength Gratings and Vertical Cavity Lasers Employing Grating Structures

    DEFF Research Database (Denmark)

    Taghizadeh, Alireza

    . Though both sides of the grating layer are not surrounded by low refractive-index materials as in high-index-contrast gratings (HCGs), the HG can provide a near-unity reflectivity over a broader wavelength range than HCGs, or work as a resonator with a quality (Q) factor as high as 109. The physics...... behind these reflector and resonator properties are studied thoroughly. A HG structure comprising a III-V cap layer with a gain material and a Si grating layer enables the realization of a compact vertical cavity laser integrated on Si platform, which has a superior thermal property and fabrication......-factor is investigated, which shows that the uncertainty in the Q-factor can be several orders of magnitude larger than the uncertainty in the resonance frequency. Next, the HG is shown to possess a near-unity reflectivity in a broad wavelength range, which can be broader than the HCG, since the cap layer introduces...

  12. UV writing of advanced Bragg gratings in optical waveguides

    DEFF Research Database (Denmark)

    Jensen, Jesper Bo Damm

    2002-01-01

    The subject of this ph.d. thesis is the fabrication of Bragg gratings in optical waveguides. During the study Bragg gratings were written in both planar waveguides and optical fibers using pulsed or continuous-wave lasers operating in the ultraviolet (UV) range. The main result is the development...... were then translated into a polarizer angle profile and the Bragg grating were written using a pulsed excimer laser. Only optical fibers were used in this part of the thesis. The high quality planar waveguides used during the study were produced in the cleanroom facility at the Microelectronic Center...... hence loaded at either 100 bar or 1800 bar prior to the UV exposure. Bragg gratings with uniform coupling strength throughout the grating and apodized gratings were realized by scanning the UV beam along the waveguide with a computer controlled velocity profile. The excellent agreement between simulated...

  13. Optical Fibre Grating Refractometers for Resin Cure Monitoring.

    OpenAIRE

    Buggy, Stephen J.; Chehura, Edmon; James, Stephen W.; Tatam, Ralph P.

    2007-01-01

    The use of fibre grating refractometers as a means of monitoring the cure of a UVcured epoxy resin is presented. The wavelength shift of the attenuation bands of a long period grating and the spectral response of a tilted fibre Bragg grating sensor were measured simultaneously during the cure of the resin and compared with measurements made using a fibre optic Fresnel based refractometer. The results showed a good correlation (6 x 10 -3 rius) and illustrate the potential of ...

  14. Observation of narrowband intrinsic spectra of Brillouin dynamic gratings.

    Science.gov (United States)

    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.

  15. Neutron diffraction in materials science

    International Nuclear Information System (INIS)

    Howard, C.J.

    1996-01-01

    This article deals with applications of neutron diffraction in materials science. Most of the examples presented here involve the use of powder diffraction, which has been described earlier. In most of these, the Rietveld method has been used for neutron diffraction data, using the Rietveld method. This being an application which was largely pioneered at Lucas Heights. Examples involving single crystal diffraction and neutron polarization analysis are also included. Most of the examples are drawn from studies carried out at Lucas Heights where there is diffraction to the study of ceramics, and this will be reflected in the choice of examples to be considered here. (author)

  16. Contact Binary Asteroids

    Science.gov (United States)

    Rieger, Samantha

    2015-05-01

    Recent observations have found that some contact binaries are oriented such that the secondary impacts with the primary at a high inclination. This research investigates the evolution of how such contact binaries came to exist. This process begins with an asteroid pair, where the secondary lies on the Laplace plane. The Laplace plane is a plane normal to the axis about which the pole of a satellites orbit precesses, causing a near constant inclination for such an orbit. For the study of the classical Laplace plane, the secondary asteroid is in circular orbit around an oblate primary with axial tilt. This system is also orbiting the Sun. Thus, there are two perturbations on the secondarys orbit: J2 and third body Sun perturbations. The Laplace surface is defined as the group of orbits that lie on the Laplace plane at varying distances from the primary. If the secondary is very close to the primary, the inclination of the Laplace plane will be near the equator of the asteroid, while further from the primary the inclination will be similar to the asteroid-Sun plane. The secondary will lie on the Laplace plane because near the asteroid the Laplace plane is stable to large deviations in motion, causing the asteroid to come to rest in this orbit. Assuming the secondary is asymmetrical in shape and the bodys rotation is synchronous with its orbit, the secondary will experience the BYORP effect. BYORP can cause secular motion such as the semi-major axis of the secondary expanding or contracting. Assuming the secondary expands due to BYORP, the secondary will eventually reach the unstable region of the Laplace plane. The unstable region exists if the primary has an obliquity of 68.875 degrees or greater. The unstable region exists at 0.9 Laplace radius to 1.25 Laplace radius, where the Laplace radius is defined as the distance from the central body where the inclination of the Laplace plane orbit is half the obliquity. In the unstable region, the eccentricity of the orbit

  17. Relativistic Binaries in Globular Clusters

    Directory of Open Access Journals (Sweden)

    Matthew J. Benacquista

    2013-03-01

    Full Text Available Galactic globular clusters are old, dense star systems typically containing 10^4 – 10^6 stars. As an old population of stars, globular clusters contain many collapsed and degenerate objects. As a dense population of stars, globular clusters are the scene of many interesting close dynamical interactions between stars. These dynamical interactions can alter the evolution of individual stars and can produce tight binary systems containing one or two compact objects. In this review, we discuss theoretical models of globular cluster evolution and binary evolution, techniques for simulating this evolution that leads to relativistic binaries, and current and possible future observational evidence for this population. Our discussion of globular cluster evolution will focus on the processes that boost the production of tight binary systems and the subsequent interaction of these binaries that can alter the properties of both bodies and can lead to exotic objects. Direct N-body integrations and Fokker–Planck simulations of the evolution of globular clusters that incorporate tidal interactions and lead to predictions of relativistic binary populations are also discussed. We discuss the current observational evidence for cataclysmic variables, millisecond pulsars, and low-mass X-ray binaries as well as possible future detection of relativistic binaries with gravitational radiation.

  18. Powder Diffraction in Zeolite Science

    Science.gov (United States)

    Burton, Allen W.

    This tutorial discusses the fundamental principles of X-ray diffraction and its applications in zeolite science. The early sections review the physics of diffraction, crystal symmetry, and reciprocal space. We discuss how the intensity of diffracted radiation is affected both by geometric effects involving detection (the Lorentz-polarization factor) and by the arrangement of atoms within the crystal (the structure factor). The differences between powder diffraction and single-crystal diffraction are then described, and differences between X-ray and neutron diffraction are also discussed. Later sections describe the effects of symmetry, lattice substitution, crystallite size, residual strain, preferred orientation, and X-ray absorption. Special emphasis is placed on the proper application of the Scherrer analysis in reporting crystalize size. The principles of structure solution from direct methods and Patterson methods are then introduced, and a description of Rietveld analysis is given. Finally the effects of stacking disorder on a powder diffraction pattern are presented.

  19. Nanoporous Polymeric Grating-Based Optical Biosensors (Preprint)

    National Research Council Canada - National Science Library

    Hsiao, Vincent K; Waldeisen, John R; Lloyd, Pamela F; Bunning, Timothy J; Huang, Tony J

    2007-01-01

    .... The fabrication process of the nanoporous polymeric grating involves holographic interference patterning and a functionalized pre-polymer syrup that facilitates the immobilization of biomolecules...

  20. Grating coupler on single-crystal lithium niobate thin film

    Science.gov (United States)

    Chen, Zhihua; Wang, Yiwen; Jiang, Yunpeng; Kong, Ruirui; Hu, Hui

    2017-10-01

    The grating coupler on single-crystal lithium niobate thin film (lithium niobate on insulator, LNOI) was designed. A bottom reflector was added in the LNOI material to improve the coupling efficiency. The grating structure was optimized by FDTD method. The material parameters such as layer thickness of lithium niobate thin film, SiO2 thickness were discussed with respect to the coupling efficiency, and the tolerances of grating period, etch depth, groove width and fiber position were also studied systematically. The simulated maximum coupling efficiency from a grating coupler with (without) bottom reflector to a single-mode fiber is about 78% (40%) in z-cut LNOI for TE polarization.

  1. Concave Grating Enabled Compact Mid-IR Upconversion Spectrometer

    DEFF Research Database (Denmark)

    Barh, Ajanta; Tidemand-Lichtenberg, Peter; Pedersen, Christian

    2017-01-01

    The paper demonstrates a wide-band (3.6 - 4.8 µm) compact mid-infrared grating spectrometer combining a nonlinear frequency upconversion process and a flat-field aberration corrected concave grating with overall system dimension of 25cm×50cm.......The paper demonstrates a wide-band (3.6 - 4.8 µm) compact mid-infrared grating spectrometer combining a nonlinear frequency upconversion process and a flat-field aberration corrected concave grating with overall system dimension of 25cm×50cm....

  2. Astrophysical targets of the Fresnel diffractive imager

    Science.gov (United States)

    Koechlin, L.; Deba, P.; Raksasataya, T.

    2017-11-01

    The Fresnel Diffractive imager is an innovative concept of distributed space telescope, for high resolution (milli arc-seconds) spectro-imaging in the IR, visible and UV domains. This paper presents its optical principle and the science that can be done on potential astrophysical targets. The novelty lies in the primary optics: a binary Fresnel array, akin to a binary Fresnel zone plate. The main interest of this approach is the relaxed manufacturing and positioning constraints. While having the resolution and imaging capabilities of lens or mirrors of equivalent size, no optical material is involved in the focusing process: just vacuum. A Fresnel array consists of millions void subapertures punched into a large and thin opaque membrane, that focus light by diffraction into a compact and highly contrasted image. The positioning law of the aperture edges drives the image quality and contrast. This optical concept allows larger and lighter apertures than solid state optics, aiming to high angular resolution and high dynamic range imaging, in particular for UV applications. Diffraction focusing implies very long focal distances, up to dozens of kilometers, which requires at least a two-vessel formation flying in space. The first spacecraft, "the Fresnel Array spacecraft", holds the large punched foil: the Fresnel Array. The second, the "Receiver spacecraft" holds the field optics and focal instrumentation. A chromatism correction feature enables moderately large (20%) relative wavebands, and fields of a few to a dozen arc seconds. This Fresnel imager is adapted to high contrast stellar environments: dust disks, close companions and (we hope) exoplanets. Specific to the particular grid-like pattern of the primary focusing zone plate, is the very high dynamic range achieved in the images, in the case of compact objects. Large stellar photospheres may also be mapped with Fresnel arrays of a few meters opertaing in the UV. Larger and more complex fields can be imaged with

  3. Spectral properties of binary asteroids

    Science.gov (United States)

    Pajuelo, Myriam; Birlan, Mirel; Carry, Benoît; DeMeo, Francesca E.; Binzel, Richard P.; Berthier, Jérôme

    2018-04-01

    We present the first attempt to characterize the distribution of taxonomic class among the population of binary asteroids (15% of all small asteroids). For that, an analysis of 0.8-2.5{μ m} near-infrared spectra obtained with the SpeX instrument on the NASA/IRTF is presented. Taxonomic class and meteorite analog is determined for each target, increasing the sample of binary asteroids with known taxonomy by 21%. Most binary systems are bound in the S-, X-, and C- classes, followed by Q and V-types. The rate of binary systems in each taxonomic class agrees within uncertainty with the background population of small near-Earth objects and inner main belt asteroids, but for the C-types which are under-represented among binaries.

  4. Planets in Binary Star Systems

    CERN Document Server

    Haghighipour, Nader

    2010-01-01

    The discovery of extrasolar planets over the past decade has had major impacts on our understanding of the formation and dynamical evolution of planetary systems. There are features and characteristics unseen in our solar system and unexplainable by the current theories of planet formation and dynamics. Among these new surprises is the discovery of planets in binary and multiple-star systems. The discovery of such "binary-planetary" systems has confronted astrodynamicists with many new challenges, and has led them to re-examine the theories of planet formation and dynamics. Among these challenges are: How are planets formed in binary star systems? What would be the notion of habitability in such systems? Under what conditions can binary star systems have habitable planets? How will volatiles necessary for life appear on such planets? This volume seeks to gather the current research in the area of planets in binary and multistar systems and to familiarize readers with its associated theoretical and observation...

  5. On symmetric X-ray beam splitting with high efficiency by use of reflection gratings with rectangular profile in the extreme off-plane configuration.

    Science.gov (United States)

    Jark, Werner; Eichert, Diane

    2015-08-24

    In order to be reflected or diffracted off a surface structure soft X-rays and hard X-rays need to impinge at grazing angles of incidence onto the surface. In case of a reflection grating of highly symmetric structure with rectangular groove profile these grooves can be oriented parallel to the beam trajectory. In such a symmetric situation the distribution of the diffracted intensity with respect to the plane of incidence is then expected to be symmetric. This is indeed observed with symmetrically oriented diffraction peaks. It can be predicted that for appropriate structure parameters the intensity can be contained mostly in two symmetrically oriented diffraction peaks. This will also be the case for hard X-rays. The diffraction efficiency will be particularly high, when the angle of grazing incidence is chosen in the total reflection regime below the critical angle of the grating coating. These predictions were experimentally verified in this work for hard X-rays with photon energies between 4 keV and 12.4 keV. In the experiment of the order of 30% of the incident intensity was diffracted into the two first orders. This is to be compared to reflectivities of the order of 50% measured at the same coating in an unruled area of the substrate. Consequently the relative structural diffraction efficiency for each first order was about 30%, while ideally it could have been 40%. The presented grating structure will thus be a rather efficient amplitude beam splitter for hard X-rays, e.g. in the coherent beam from a free electron laser. In addition such object could then be used as the first component in Michelson interferometers for the beam characterisation or for introducing a time delay between two coherent beams.

  6. BINARY ASTROMETRIC MICROLENSING WITH GAIA

    Energy Technology Data Exchange (ETDEWEB)

    Sajadian, Sedighe, E-mail: sajadian@ipm.ir [School of Astronomy, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Department of Physics, Sharif University of Technology, P.O. Box 11155-9161, Tehran (Iran, Islamic Republic of)

    2015-04-15

    We investigate whether or not Gaia can specify the binary fractions of massive stellar populations in the Galactic disk through astrometric microlensing. Furthermore, we study whether or not some information about their mass distributions can be inferred via this method. In this regard, we simulate the binary astrometric microlensing events due to massive stellar populations according to the Gaia observing strategy by considering (i) stellar-mass black holes, (ii) neutron stars, (iii) white dwarfs, and (iv) main-sequence stars as microlenses. The Gaia efficiency for detecting the binary signatures in binary astrometric microlensing events is ∼10%–20%. By calculating the optical depth due to the mentioned stellar populations, the numbers of the binary astrometric microlensing events being observed with Gaia with detectable binary signatures, for the binary fraction of about 0.1, are estimated to be 6, 11, 77, and 1316, respectively. Consequently, Gaia can potentially specify the binary fractions of these massive stellar populations. However, the binary fraction of black holes measured with this method has a large uncertainty owing to a low number of the estimated events. Knowing the binary fractions in massive stellar populations helps with studying the gravitational waves. Moreover, we investigate the number of massive microlenses for which Gaia specifies masses through astrometric microlensing of single lenses toward the Galactic bulge. The resulting efficiencies of measuring the mass of mentioned populations are 9.8%, 2.9%, 1.2%, and 0.8%, respectively. The numbers of their astrometric microlensing events being observed in the Gaia era in which the lens mass can be inferred with the relative error less than 0.5 toward the Galactic bulge are estimated as 45, 34, 76, and 786, respectively. Hence, Gaia potentially gives us some information about the mass distribution of these massive stellar populations.

  7. Imaging spectroscopy using embedded diffractive optical arrays

    Science.gov (United States)

    Hinnrichs, Michele; Hinnrichs, Bradford

    2017-09-01

    Pacific Advanced Technology (PAT) has developed an infrared hyperspectral camera based on diffractive optic arrays. This approach to hyperspectral imaging has been demonstrated in all three infrared bands SWIR, MWIR and LWIR. The hyperspectral optical system has been integrated into the cold-shield of the sensor enabling the small size and weight of this infrared hyperspectral sensor. This new and innovative approach to an infrared hyperspectral imaging spectrometer uses micro-optics that are made up of an area array of diffractive optical elements where each element is tuned to image a different spectral region on a common focal plane array. The lenslet array is embedded in the cold-shield of the sensor and actuated with a miniature piezo-electric motor. This approach enables rapid infrared spectral imaging with multiple spectral images collected and processed simultaneously each frame of the camera. This paper will present our optical mechanical design approach which results in an infrared hyper-spectral imaging system that is small enough for a payload on a small satellite, mini-UAV, commercial quadcopter or man portable. Also, an application of how this spectral imaging technology can easily be used to quantify the mass and volume flow rates of hydrocarbon gases. The diffractive optical elements used in the lenslet array are blazed gratings where each lenslet is tuned for a different spectral bandpass. The lenslets are configured in an area array placed a few millimeters above the focal plane and embedded in the cold-shield to reduce the background signal normally associated with the optics. The detector array is divided into sub-images covered by each lenslet. We have developed various systems using a different number of lenslets in the area array. Depending on the size of the focal plane and the diameter of the lenslet array will determine the number of simultaneous different spectral images collected each frame of the camera. A 2 x 2 lenslet array will image

  8. High-accuracy measurement and compensation of grating line-density error in a tiled-grating compressor

    Science.gov (United States)

    Zhao, Dan; Wang, Xiao; Mu, Jie; Li, Zhilin; Zuo, Yanlei; Zhou, Song; Zhou, Kainan; Zeng, Xiaoming; Su, Jingqin; Zhu, Qihua

    2017-02-01

    The grating tiling technology is one of the most effective means to increase the aperture of the gratings. The line-density error (LDE) between sub-gratings will degrade the performance of the tiling gratings, high accuracy measurement and compensation of the LDE are of significance to improve the output pulses characteristics of the tiled-grating compressor. In this paper, the influence of LDE on the output pulses of the tiled-grating compressor is quantitatively analyzed by means of numerical simulation, the output beams drift and output pulses broadening resulting from the LDE are presented. Based on the numerical results we propose a compensation method to reduce the degradations of the tiled grating compressor by applying angular tilt error and longitudinal piston error at the same time. Moreover, a monitoring system is setup to measure the LDE between sub-gratings accurately and the dispersion variation due to the LDE is also demonstrated based on spatial-spectral interference. In this way, we can realize high-accuracy measurement and compensation of the LDE, and this would provide an efficient way to guide the adjustment of the tiling gratings.

  9. Effect of particle-size selectivity on quantitative X-ray dark-field computed tomography using a grating interferometer

    Science.gov (United States)

    Bao, Yuan; Shao, Qigang; Hu, Renfang; Wang, Shengxiang; Gao, Kun; Wang, Yan; Tian, Yangchao; Zhu, Peiping

    2017-08-01

    According to the conclusion of Khelashvili et al. [Phys. Med. Biol. 51, 221 (2006)], the minus logarithm of the visibility ratio fulfills the line integral condition; consequently the scattering information can be reconstructed quantitatively by conventional computed tomography (CT) algorithms. Based on Fresnel diffraction theory, we analyzed the influence of particle-size selectivity on the performance of an X-ray grating interferometer (GI) applied for dark-field CT. The results state the signal-to-noise ratio (SNR) of dark-field imaging is sensitive to the particle size, which demonstrate that the X-ray dark-field CT using a GI can efficiently differentiate materials of identical X-ray absorption and help to choose optimal X-ray energy for known particle size, thus extending the application range of grating interferometer.

  10. Low-Dispersion Fibre Bragg Gratings Written Using the Polarization Control Method

    DEFF Research Database (Denmark)

    Deyerl, Hans Jürgen; Plougmann, Nikolai; Jensen, Jesper Bo Damm

    2002-01-01

    We present two fibre Bragg gratings with reduced in-band dispersion for DWDM applications. The gratings were designed by the inverse scattering method and fabricated using the novel polarization control method for UV-writing of advanced gratings.......We present two fibre Bragg gratings with reduced in-band dispersion for DWDM applications. The gratings were designed by the inverse scattering method and fabricated using the novel polarization control method for UV-writing of advanced gratings....

  11. Highly compact polarization-independent grating coupler.

    Science.gov (United States)

    Shao, Shiqian; Wang, Yi

    2010-06-01

    We propose a compact polarization-independent output grating coupler, which consists of T-shaped grooves. For only 20 periods on a silicon-on-insulator wafer with a 260nm thick top silicon layer, the output coupling efficiencies for both the TE and the TM modes are larger than 50% in the wavelength range of 1480-1580nm and are approximately 58% around 1550nm. The polarization-dependent loss of the device is within 0.05dB in the range of 1510-1580nm.

  12. Imaging Grating Spectrometer (I-GRASP) for Solar Soft X-Ray Spectral Measurements in Critically Under-Observed 0.5 - 7 nm Spectral Range

    Science.gov (United States)

    Didkovsky, L. V.; Wieman, S. R.; Chao, W.; Woods, T. N.; Jones, A. R.; Thiemann, E.; Mason, J. P.

    2016-12-01

    We discuss science and technology advantages of the Imaging Grating Spectrometer (I-GRASP) based on a novel transmission diffracting grating (TDG) made possible by technology for fabricating Fresnel zone plates (ZPs) developed at the Lawrence Berkeley National Laboratory (LBNL). Older version TDGs with 200 nm period available in the 1990s became a proven technology for providing 21 years of regular measurements of solar EUV irradiance. I-GRASP incorporates an advanced TDG with a grating period of 50 nm providing four times better diffraction dispersion than the 200 nm period gratings used in the SOHO/CELIAS/SEM, the SDO/EVE/ESP flight spectrophotometers, and the EVE/SAM sounding rocket channel. Such new technology for the TDG combined with a back-illuminated 2000 x 1504 CMOS image sensor with 7 micron pixels, will provide spatially-and-spectrally resolved images and spectra from individual Active Regions (ARs) and solar flares with high (0.15 nm) spectral resolution. Such measurements are not available in the spectral band from about 2 to 6 nm from existing or planned spectrographs and will be significantly important to study ARs and solar flare temperatures and dynamics, to improve existing spectral models, e.g. CHIANTI, and to better understand processes in the Earth's atmosphere processes. To test this novel technology, we have proposed to the NASA LCAS program an I-GRASP version for a sounding rocket flight to increase the TDG TRL to a level appropriate for future CubeSat projects.

  13. EFFECT OF OPTICAL FIBER HYDROGEN LOADING ON THE INSCRIPTION EFFICIENCY OF CHIRPED BRAGG GRATINGS BY MEANS OF KrF EXCIMER LASER RADIATION

    Directory of Open Access Journals (Sweden)

    Sergey V. Varzhel

    2016-11-01

    Full Text Available Subject of Research.We present comparative results of the chirped Bragg gratings inscription efficiency in optical fiber of domestic production with and without low-temperature hydrogen loading. Method. Chirped fiber Bragg gratings inscription was made by the Talbot interferometer with chirped phase mask having a chirp rate of 2.3 nm/cm used for the laser beam amplitude separation. The excimer laser system Coherent COMPexPro 150T, working with the gas mixture KrF (248 nm, was used as the radiation source. In order to increase the UV photosensitivity, the optical fiber was placed in a chamber with hydrogen under a pressure of 10 MPa and kept there for 14 days at 40 °C. Main Results. The usage of the chirped phase mask in a Talbot interferometer scheme has made it possible to get a full width at half-maximum of the fiber Bragg grating reflection spectrum of 3.5 nm with induced diffraction structure length of 5 mm. By preliminary hydrogen loading of optical fiber the broad reflection spectrum fiber Bragg gratings with a reflectivity close to 100% has been inscribed. Practical Relevance. The resulting chirped fiber Bragg gratings can be used as dispersion compensators in optical fiber communications, as well as the reflective elements of distributed fiber-optic phase interferometric sensors.

  14. Diffraction radiation from relativistic particles

    International Nuclear Information System (INIS)

    Potylitsyn, Alexander Petrovich; Ryazanov, Mikhail Ivanovich; Strikhanov, Mikhail Nikolaevich; Tishchenko, Alexey Alexandrovich

    2010-01-01

    This book deals with diffraction radiation, which implies the boundary problems of electromagnetic radiation theory. Diffraction radiation is generated when a charged particle moves in a vacuum near a target edge. Diffraction radiation of non-relativistic particles is widely used to design intense emitters in the cm wavelength range. Diffraction radiation from relativistic charged particles is important for noninvasive beam diagnostics and design of free electron lasers based on Smith-Purcell radiation which is diffraction radiation from periodic structures. Different analytical models of diffraction radiation and results of recent experimental studies are presented in this book. The book may also serve as guide to classical electrodynamics applications in beam physics and electrodynamics. It can be of great use for young researchers to develop skills and for experienced scientists to obtain new results. (orig.)

  15. Diffraction radiation from relativistic particles

    CERN Document Server

    Potylitsyn, Alexander Petrovich; Strikhanov, Mikhail Nikolaevich; Tishchenko, Alexey Alexandrovich

    2010-01-01

    This book deals with diffraction radiation, which implies the boundary problems of electromagnetic radiation theory. Diffraction radiation is generated when a charged particle moves in a vacuum near a target edge. Diffraction radiation of non-relativistic particles is widely used to design intense emitters in the cm wavelength range. Diffraction radiation from relativistic charged particles is important for noninvasive beam diagnostics and design of free electron lasers based on Smith-Purcell radiation which is diffraction radiation from periodic structures. Different analytical models of diffraction radiation and results of recent experimental studies are presented in this book. The book may also serve as guide to classical electrodynamics applications in beam physics and electrodynamics. It can be of great use for young researchers to develop skills and for experienced scientists to obtain new results.

  16. Content identification: binary content fingerprinting versus binary content encoding

    Science.gov (United States)

    Ferdowsi, Sohrab; Voloshynovskiy, Svyatoslav; Kostadinov, Dimche

    2014-02-01

    In this work, we address the problem of content identification. We consider content identification as a special case of multiclass classification. The conventional approach towards identification is based on content fingerprinting where a short binary content description known as a fingerprint is extracted from the content. We propose an alternative solution based on elements of machine learning theory and digital communications. Similar to binary content fingerprinting, binary content representation is generated based on a set of trained binary classifiers. We consider several training/encoding strategies and demonstrate that the proposed system can achieve the upper theoretical performance limits of content identification. The experimental results were carried out both on a synthetic dataset with different parameters and the FAMOS dataset of microstructures from consumer packages.

  17. Optimally cloned binary coherent states

    Science.gov (United States)

    Müller, C. R.; Leuchs, G.; Marquardt, Ch.; Andersen, U. L.

    2017-10-01

    Binary coherent state alphabets can be represented in a two-dimensional Hilbert space. We capitalize this formal connection between the otherwise distinct domains of qubits and continuous variable states to map binary phase-shift keyed coherent states onto the Bloch sphere and to derive their quantum-optimal clones. We analyze the Wigner function and the cumulants of the clones, and we conclude that optimal cloning of binary coherent states requires a nonlinearity above second order. We propose several practical and near-optimal cloning schemes and compare their cloning fidelity to the optimal cloner.

  18. Microstructure, Interaction Mechanisms, and Stability of Binary Systems Containing Goethite and Kaolinite

    NARCIS (Netherlands)

    Wei, S.Y.; Tan, W.F.; Zhao, W.; Yu, Y.T.; Liu, F.; Koopal, L.K.

    2012-01-01

    Goethite and kaolinite are ubiquitous in natural environments. In soils they are often cemented together as a binary association, which has a significant influence on the structure and properties of soils. In this study, the mineralogy (using X-ray diffraction [XRD], thermal analyses, and infrared

  19. Three-dimensional optical techniques using Dammann gratings

    Science.gov (United States)

    Zhou, Changhe; Yu, Junjie; Wang, Shaoqing; Wei, Shengbin

    2012-11-01

    This paper summarized our work on three-dimensional optical technologies using Dammann gratings, e.g., threedimnensional Dammann gratings, three dimensional imaging using a Dammann grating, etc.. We developed threedimensional Dammann grating which can produce three-dimensional array with equal distance and equal intensity with a high-numerical-aperture lens. As we know, a lens usually has a single focal point. Fresnel zone plate can generate several axial focal points, but the intensity between them is unequal. By introducing the concept of Dammann grating into the circular phase plate, we invented Dammann zone plate(DZP) which can produce a series of axial focal points with equal intensity. Combining DZP with a Dammann grating, three-dimensional Dammann array will be generated, which is highly interesting for various applications. We also built a three-dimensional measuring system using a Dammann grating, with two cameras as the right eye and right eye, respectively. We used a 64×64 Dammann grating for generation of a square array of light spots for parallel capturing the three-dimensional profile of an object. The two cameras and the illuminating part are packaged together. After scanning the object, its three-dimensional profile will be obtained. Experimental results demonstrated the effectiveness of this technique.

  20. Analysis of the optical parameters of phase holographic gratings

    Directory of Open Access Journals (Sweden)

    Є.О. Тихонов

    2008-03-01

    Full Text Available  Suitability of 2- wave approximation of the coupled waves theory tor description of holographic phase gratings recorded on photopolymer compound ФПК-488 is proved. Using the basic formulas of the theory, main grating optical parameters - a depth of modulation and finished thickness are not measured immediately are determined.