Sample records for relief grating srg

  1. Stochastic model for photoinduced surface relief grating formation through molecular transport in polymer films.

    Juan, M.; Plain, J.; Bachelot, R.; Royer, P.; Gray, S. K.; Wiederrecht, G. P.; Univ. de Technologie de Troyes


    We use a stochastic model to study photoinduced surface relief grating (SRG) formation due to molecular transport in azobenzene polymer films. The model is shown to reproduce the essential experimental features of SRG formation. In particular, it predicts SRG formation under both p and s polarizations, and the double peaked topographies that can occur at early times of the process. The evolving molecular positions and orientations during exposure are also followed, providing a useful mechanistic picture of SRG dynamics.

  2. Formation of surface relief gratings with homeotropically oriented photopolymer from a photocross-linkable organic monomer.

    Zhao, Dongyu; Xu, Zeda; Wang, Guojie; Cao, Hui; Li, Wenbo; He, Wanli; Huang, Wei; Yang, Zhou; Yang, Huai


    In this communication, we describe a simple process for the generation of surface relief gratings (SRG). SRG are fabricated from a photocross-linkable organic monomer PDACE (4-propyldiphenylacetylenecarboxylic acid cinnamyl ester) with cinnamyl ester and tolane groups, by using a patterned non-polarized UV light irradiation. The patterns of the surface relief structures can be easily controlled and the modulation depth can reach 130 nm. Moreover, it is interestingly observed that the photopolymer of the SRG exhibits distinctive characteristics including homeotropic orientation and fluorescence properties as a result of the photocross-linking of the dual photoreactive groups of PDACE. Finally, the mechanism of fabrication of SRG from PDACE is discussed with mean-field theory.

  3. Hollow-core grating fiber

    Barillé, R.; Tajalli, P.; Roy, P.; Ahmadi-kandjani, S.; Kucharski, S.; Ortyl, E.


    We propose a new type of hollow-core fiber where the propagation is ensured by a photoinduced self-pattern acting as a surface relief grating (SRG). The SRG is written by launching a suitable laser beam with proper polarization in a capillary glass fiber with the inner surface previously coated with an azopolymer thin film. Such a grating acts as a wavelength/angle dependant reflective mirror and enhances the confinement and the propagation of the light.

  4. Surface-relief and polarization gratings for solar concentrators.

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


    Transmission gratings that combine a large diffraction angle with a high diffraction efficiency and a low angular and wavelength dispersion could be used to collect sunlight in a light guide. In this paper we compare the diffractive properties of polarization gratings and classical surface-relief gratings and explore their possible use in solar concentrators. It is found that polarization gratings and surface-relief gratings have qualitatively comparable diffraction characteristics when their thickness parameters are within the same regime. Relatively large grating periods result in high diffraction efficiencies over a wide range of incident angles. For small grating periods the efficiency and the angular acceptance are decreased. Surface-relief gratings are preferred over polarization gratings as in-couplers for solar concentrators.

  5. Effective grating theory for resonance domain surface-relief diffraction gratings.

    Golub, Michael A; Friesem, Asher A


    An effective grating model, which generalizes effective-medium theory to the case of resonance domain surface-relief gratings, is presented. In addition to the zero order, it takes into account the first diffraction order, which obeys the Bragg condition. Modeling the surface-relief grating as an effective grating with two diffraction orders provides closed-form analytical relationships between efficiency and grating parameters. The aspect ratio, the grating period, and the required incidence angle that would lead to high diffraction efficiencies are predicted for TE and TM polarization and verified by rigorous numerical calculations.

  6. Spontaneous formation of optically induced surface relief gratings

    Leblond, H; Ahamadi-kandjani, S; Nunzi, J -M; Ortyl, E; Kucharski, S


    A model based on Fick's law of diffusion as a phenomenological description of the molecular motion, and on the coupled mode theory, is developped to describe single-beam surface relief grating formation in azopolymers thin films. It allows to explain the mechanism of spontaneous patterning, and self-organization. It allows also to compute the surface relief profile and its evolution in time with good agreement with experiments.

  7. SRG Inscription in Supramolecular Liquid Crystalline Polymer Film: Replacement of Mesogens

    Shun Mitsui


    Full Text Available The photoinduced surface relief formation via mass transfer upon irradiation with patterned light has long been a subject of extensive investigation. In azobenzene-containing liquid crystalline materials, UV light irradiation that generates the cis isomer leads to the liquid crystal to isotropic photochemical transition. Due to this phase change, efficiency of the mass transfer to generate a surface relief grating (SRG becomes markedly greater. We have previously indicated that azobenzene-colored SRG-inscribed film can be bleached by removing a hydrogen-bonded azobenzene mesogen. However, this process largely reduces the height feature of the SRG corrugation. Herein, we propose an extended procedure where a colorless mesogen is filled successively after the removal of the azobenzene side chain. The process involves four stages: (i SRG inscription in a hydrogen-bonded supramolecular azobenzene material; (ii crosslinking (insolubilization of the SRG film; (iii removal of azobenzene mesogen by rinsing with a solvent, and (iv stuffing the hollow film with a different mesogen. Although the final stuffing stage was insufficient at the present stage, this work demonstrates the possibility and validity of the strategy of mesogen replacement.

  8. Diffraction from relief gratings on a biomimetic elastomer cast

    Guerrero, Raphael A., E-mail: [Department of Physics, Ateneo de Manila University, Loyola Heights, Quezon City (Philippines); Aranas, Erika B. [Department of Physics, Ateneo de Manila University, Loyola Heights, Quezon City (Philippines)


    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.

  9. Topology-optimized broadband surface relief transmission grating

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


    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 pla......% in a broadband range going from the ultraviolet region, through the visible region and into the near-infrared region....

  10. Photofabrication of surface relief gratings using post functionalized azo polymers

    Tripathy, S.K.; Kumar, J.; Kim, D.Y.; Jiang, X.; Wang, X.; Li, L.; Sukwattanasinitt, M.; Sandman, D.J.


    A series of azobenzene funtionalized polymers has been synthesized by post polymerization azo coupling reaction. Photo-fabrication of surface relief gratings were studied on the polymer films. Epoxy based azo polymers were prepared by post azo coupling reaction to form polymers containing donor-acceptor type azo chromophores. The azo chromophores were designed to contain ionizable groups to impart self-assembling and photoprocessing capabilities to the polymers. The polymers containing 4-(4-(carboxylic acid)phenylazo)aniline chromophores can be directly photofabricated to form surface relief gratings with large surface modulations. Charge interactions had a strong influence on the details of the writing process. A new soluble polydiacetylene, post-functionalized with azobenzene groups was also prepared. Large amplitude surface gratings could be fabricated on this polydiacetylene film as well.

  11. Unraveling the nucleation and growth of spontaneous surface relief gratings

    Mazaheri, Leila; Sabat, Ribal Georges; Lebel, Olivier; Nunzi, Jean-Michel


    Nucleation and growth of spontaneous surface relief gratings (SSRGs) on a Disperse Red 1 (DR1) glass-forming derivative were investigated. No interference pattern is applied and surface patterning is induced using single-beam irradiation: the gratings are self-organized. Grating growth is assumed to initiate from an interference pattern formed between the incident light beam and waves scattered at grazing angle by surface defects. However, the mechanism is not yet fully understood and there is not a comprehensive explanation of the structure formation process. Herein, the grating formation procedure is studied by monitoring the surface topology of thin films exposed to one writing beam for various periods of time, under both linear and circular polarizations, using AFM. Even in the absence of surface defects on the initial film, irradiation produces light-induced surface defects due to the reorientation and mass movement of the azo molecules. These defects act as seeds for SSRG around which gratings gradually emerge and propagate throughout the sample. To consolidate this hypothesis, the formation of gratings was studied on samples with controlled surface roughness. Pore-shaped defects do not diffract light on top of the sample, and thus have no impact on SSRG growth, while for hill-shaped defects, growth rate decreases sharply with defect sizes larger than the writing beam wavelength. Two other analogous glass-forming azobenzene derivatives were studied, and in all cases, SSRG formation was correlated with the induction of birefringence in the early stages of the irradiation.

  12. Photoinduced dichroism and surface-relief-gratings of hyperbranched azo polymers synthesized by azo-coupling reaction

    CHE Pengchao; HE Yaning; WANG Xiaogong


    This article reports the synthesis and photoresponsive properties of a hyperbranched azo polymer containing electron donor-acceptor type azo chromophores both in backbone and peripheral positions.For the synthesis,a hyperbranched azo precursor polymer was synthesized by step-growth polymerization of an AB2 monomer,bis[2-(N-ethylanilino)ethyl] 5-aminoisophthalate,through azocoupling reaction.The hyperbranched precursor polymer was then reacted with the diazonium salt from 4-cyanoaniline to introduce donor-acceptor azo chromophores in the peripheral groups.The resulting azo polymers were characterized by the spectroscopic methods and thermal analysis.The photo-induced dichroism of the hyperbranched polymer was studied and its orientation order parameter was estimated to be 0.063.Thin films of the hyperbranched azo polymers were used to fabricate surface-relief-gratings (SRGs) by exposing them to an interference pattern of Ar+ laser beam at modest intensities (150 mW/cm2).The azo chromophores introduced by postazo-coupling reaction at the para-positions of the peripheral azobenzenes shows a significant effect on the SRG inscription rate.The hyperbranched azo polymers can potentially be used for applications such as reversible optical data storage,photoswitch,sensors,and other photo-driven devices.

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

    Naydenova, I; Nikolova, L; Todorov, T


    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...... photobirefringences, and at larger intensity the influence of the surface relief dominates the effect of the circular anisotropy. Owing to the high recording efficiency of the polyesters, the +/-1-order diffracted waves change the polarization interference pattern during the holographic recording, resulting...... in the appearance of a surface relief with doubled frequency....

  14. Structure modeling for scatterometric characterization of photoinduced surface-relief gratings

    Logofatu, Petre C.; Apostol, Ileana; Castex, Marie-Claude; Damian, Victor; Iordache, Iuliana; Bojan, Mihaela; Apostol, Dan


    Surface-relief photo-polymer gratings obtained through the novel technique of photoinduced single step inscription in photopolymers are characterized through various investigations means, with an emphasis on scatterometry. The characterization of the gratings is necessary not only for insight in the creation process of gratings but also for checking the reproducibility and uniformity. The diffraction efficiencies of the various orders diffracted by the grating were measured and they were fitted to theoretical predictions corresponding to various structure models of the gratings. The fitting procedure is used to provide the parameters of the gratings, such as the width, the grating height, the pitch or shape factors, such as the wall angles for a trapezoidal structure. The shape of the gratings was quite complicated and the fitting, for this reason, a challenge. Numerous models were proposed, tried and their advantages and shortcomings discussed.

  15. Biphotonic holographic gratings in azobenzene polyesters: Surface relief phenomena and polarization effects

    Sánchez, C.; Alcalá, R.; Hvilsted, Søren


    Biphotonic holographic gratings have been recorded in a side-chain azobenzene liquid crystalline polyester using a blue incoherent source and a He-Ne laser. Intensity gratings and the appearance of surface relief have been observed when two linearly polarized beams from a He-Ne laser are made...

  16. Characterization of surface relief gratings of submicron period

    Logofătu, P. C.; Apostol, D.; Castex, Marie-Claude; Apostol, Ileana; Damian, V.; Iordache, Iuliana; Müller, Raluca


    This paper deals with optical characterization of photo-polymer gratings for parameter control. The gratings were obtained using the photoinduced single step inscription of refractive optical elements technique. The optical characterization was done by measuring the specular and diffracted orders of a laser beam incident on the grating. This technique is specifically known as scatterometry. The laser was a He-Ne with 633 nm wavelength. The measured diffraction efficiencies contain information about the parameters to be determined of the grating, such as pitch, linewidth and shape of the ridges.

  17. Voltage-controlled compression for period tuning of optical surface relief gratings.

    Kollosche, Matthias; Döring, Sebastian; Stumpe, Joachim; Kofod, Guggi


    This Letter reports on new methods and a consistent model for voltage tunable optical transmission gratings. Elastomeric gratings were molded from holographically written surface relief gratings in an azobenzene sol-gel material. These were placed on top of a transparent electroactive elastomeric substrate. Two different electro-active substrate elastomers were employed, with a large range of prestretches. A novel finite-deformation theory was found to match the device response excellently, without fitting parameters. The results clearly show that the grating underwent pure-shear deformation, and more surprisingly, that the mechanical properties of the electro-active substrate did not affect device actuation.

  18. Surface relief and polarization gratings for solar concentrators

    De Jong. T.M.; De Boer, D.K.G.; Bastiaansen, C.W.M.


    Transmission gratings that combine a large diffraction angle with ahigh diffraction efficiency and low angular and wavelength dispersion could be used to collect sunlight in a light guide. In this paperwe determine what characteristics a grating should have in order tobe useful for such a solar

  19. Femtosecond laser induced index and relief gratings in polymer films

    Yi Dong; Xiaoqiang Yu; Yuming Sun; Yufei Li; Xueyuan Hou; Xian Zhang


    A true single-step process suitable for fabrication of micro-periodic structure in polymer films by two photon initiated photopolymerization and laser ablation is presented. By the right choice of the irradiation energy, the irradiated zone is modified or ablated in the 1.44-μm-thick film. The mechanism of grating generation and the potential application of the gratings in integrated optics are discussed.

  20. Study of surface relief gratings on azo organometallic films in picosecond regime.

    Luc, J; Bouchouit, K; Czaplicki, R; Fillaut, J-L; Sahraoui, B


    Materials for optical data storage and optical information processing must exhibit good holographic properties. Many materials for these applications have been already proposed. Here we describe a grating inscription process characterized by short inscription time and long-time stability. A series of ruthenium-acetylide organometallic complexes containing an azobenzene fragment were synthesized. Photo-induced gratings were produced by short pulse (16 ps, 532 nm) laser irradiation. The surface relief gratings formed at the same time were observed by atomic force microscope. In this work, we highlight the short inscription times brought into play as well as the good temporal stability of these gratings stored at room temperature. We study the influence of the polarization states and the light intensity of writing beams on the dynamics of the surface relief gratings formation and we compare these results with those of a known representative of azobenzene derivative (Disperse Red 1). Lastly, we show that it is possible to write two-dimensional surface relief gratings.

  1. Optimization for sinusoidal profiles in surface relief gratings recorded on photoresist

    Sanjiva Kumar; Amrita Debnath; R B Tokas; K Divakar Rao; D V Udupa; N K Sahoo


    The formations of sinusoidal surface relief structures recorded in positive photoresist (Allresist AR-P 3120) have been studied and optimized for different recording parameters of gratings with spatial frequency of∼1200 grooves/mm.Astable sinusoidal pattern generated using a two-beam laser interferometric technique was recorded in thin films of positive photoresist deposited on glass substrates. Several gratings were generated by varying the exposure time of interference pattern and time of chemical development of exposed media. Time duration of exposure for 90 s and chemical development for 15 s were observed to be optimum for the translation of the sinusoidal interference pattern into nearly-sinusoidal profiled grooves in the gratings for a developer AR-300-26 of dilution of 2:1 (developer:de-ionized water).

  2. GISAXS study of Au-coated light-induced polymer gratings

    Castro-Colin, M., E-mail:; Korolkov, D. [Bruker AXS, Rheinbrueckenstr. 49, 76187 Karlsruhe (Germany); Yadavalli, N. S. [Nanostructured Materials Lab, The University of Georgia, 30602 Athens, Georgia (United States); Mayorova, M.; Kentzinger, M. [Research Center Juelich, 52425 Juelich (Germany); Santer, S. [Institute of Physics and Astronomy, University of Potsdam, 14476 Potsdam (Germany)


    Surface Relief Gratings (SRGs) are inscribed in the Au-coated azobenzene containing photosensitive polymer films on a glass substrate. The structures consist of micrometer-period sinusoidal patterns of sub-micron amplitudes, formed by photo-isomerization and molecular reorientation processes in the polymer film during exposure to the light interference pattern that drove the formation of a SRG; the precursor is a stack sequence of Au, polymer, and glass. The SRG structures were exposed in GISAXS geometry to high-intensity X-ray radiation from a liquid Ga source (0.134 nm). Scattered photons were registered by a 2D detector, and their intensity distribution enabled us to characterize the structures. Analysis of the 2D patterns yielded information about the pitch of the gratings as well as the thickness of the films forming the gratings. The GISAXS experiments were carried out at the Research Center Juelich.

  3. The influence of diffraction gratings relief noise on the intensity distribution in diffraction orders

    Kolyuchkin, V. V.; Odinokov, S. B.


    The method of security hologram quality inspection, in which the relief phase parameters are determined by registering results of the intensity distribution in diffraction orders, is known. The profile of relief as a harmonious distribution is represented. Deviation of the real relief profile from the ideal profile, another words phase relief noise, influence on the accuracy of this method. In the paper, on the assumption of homogeneity of the phase relief noise, the mathematical expressions for evaluating the influence of the phase relief noise on the intensity distribution in the diffraction orders are represented. Parameters of the correlation functions approximation describing the phase relief noise are determined. The dependence of the intensity values from the standard deviation of the phase relief noise is represented.

  4. Quality inspection of security holograms considering the influence of diffraction grating relief distortions

    Kolyuchkin, V. V.; Odinokov, S. B.; Tsyganov, I. K.


    Security holograms are widely used for authenticity protection of documents and products due to difficulties of such a protection mark falsification. The quality of holograms significantly depends on accordance of calculated and real phase relief parameters. We represent the method for automated quality inspection of security holograms. This method based on determining of phase relief parameters by registered results of the intensity distribution in diffraction orders. The profile of relief as a harmonious distribution is represented. Distortion of the ideal relief profile influence on the accuracy of this method. The mathematical expressions for evaluating the influence of the phase relief distortion on the intensity distribution in the diffraction orders are represented. Parameters of the correlation functions approximation describing the relief distortion are determined. The dependence of the intensity values on the standard deviation of the relief distortion is represented. The results of quality inspection for real security holograms are shown.

  5. Synthesis, self-assembly and photoinduced surface-relief gratings of a polyacrylate-based Azo polyelectrolyte

    He, Yaning; Wang, Haopeng; Tuo, Xinlin; Deng, Wei; Wang, Xiaogong


    A polyacrylate-based azo polyelectrolyte was synthesized and characterized by the spectroscopic methods and thermal analysis. Layer-by-layer self-assembly of the azo polyelectrolyte through electrostatic adsorption was explored. By using a dipping solution of the anionic azo polyelectrolyte in anhydrous DMF, together with an aqueous solution of cationic poly(diallyldimethylammonium chloride) (PDAC), high quality multilayer films were obtained through the sequential deposition of the oppositely charged polyelectrolytes. With interfering illumination of Ar + laser beams (488 nm), significant surface-relief gratings formed on the self-assembled multiplayer films were observed.

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

    Sergio Calixto


    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.

  7. XSPECT telescopes on the SRG: optical performance

    Westergaard, Niels Jørgen Stenfeldt; Polny, Josef; Christensen, Finn Erland


    The XSPECT, thin foil, multiply nested telescope on SRG has been designed to achieve a large effective area at energies between 6 and 15 keV. The design goal for the angular resolution is 2 arcmin (HPD). Results of foil figure error measurements are presented. A ray tracing analysis was performed...

  8. Surface Plasmon Polariton Excitation in Metallic Layer Via Surface Relief Gratings in Photoactive Polymer Studied by the Finite-Difference Time-Domain Method.

    Karpinski, Pawel; Miniewicz, Andrzej


    We performed numerical investigations of surface plasmon excitation and propagation in structures made of a photochromic polymer layer deposited over a metal surface using the finite-difference time-domain method. We investigated the process of light coupling into surface plasmon polariton excitation using surface relief gratings formed on the top of a polymer layer and compared it with the coupling via rectangular ridges grating made directly in the metal layer. We also performed preliminary studies on the influence of refractive index change of photochromic polymer on surface plasmon polariton propagation conditions.

  9. pH-responsive one-dimensional periodic relief grating of polymer brush-gold nanoassemblies on silicon surface.

    Chen, Jem-Kun; Pai, Ping-Chun; Chang, Jia-Yaw; Fan, Shih-Kang


    In this work, we focus on the fabrication of the nanoassemblies consisting of the poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) brushes and gold nanoparticles (AuNPs). The employed process involves grafting of the PDMAEMA chains on an underlying substrate in a brush conformation followed by the immobilization of surface functionalized AuNPs by means of physical interaction (electrostatic attraction, entanglement, and hydrogen bonding). Atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and UV-vis spectroscopy have been employed to characterize the prepared PDMAEMA-AuNP nanoassemblies. Polymer brushes possessing various thicknesses have been found to suppress the nanoparticles' aggregation and, hence, facilitate the surface coverage. Furthermore, we patterned the PDMAEMA-AuNP nanoassemblies as an one-dimensional periodic relief grating (OPRG). The subwavelength structure of OPRG has the optical features including artificial refractive index, form birefringence and resonance and band gap effects. A mean refractive index of the PDMAEMA-AuNP nanoassemblies can be controlled by the filling factors of the OPRG structure, so that a desired distribution of refractive index of the polymer brushes-gold OPRG under various stimuli can be realized. The employed approach is simple and highly versatile for the modification of surfaces with a wide range of NPs.

  10. Two-dimensional periodic relief grating as a versatile platform for selective immunosorbent assay and visualizing of antigens.

    Chen, Jem-Kun; Zhou, Gang-Yan; Huang, Chih-Feng; Chang, Jia-Yaw


    In this study, we fabricated a nanopillar array of silicon oxide, involving very-large-scale integration (VLSI) and reactive ion etching (RIE), as two-dimensional periodic relief gratings (2DPRGs) on Si surfaces. Antihuman ALB was successively oriented on the pillar surface of 2DPRG modified protein G as an optical detector that is specific for targeted antigen. The antibody modified 2DPRG alone produces insignificant structure change, but upon immunocapture of antigens, the antigen filling in the 2DPRG leads to a dramatic change of the pillar scale. Binding of the antibodies to the 2DPRG occurs in a way that still allows them to function and selectively bind antigen. The performance of the sensor was evaluated by capturing HRP-human ALB on the antibody-modified 2DPRG and measuring the effective refractive index (neff) resulting from the attachment of antigens. The neff values of the 2DPRG are found to relate with the pillar scale of the 2DPRG, generated by antigen coupling, resulting in color change from pure green to orange, observed by the naked eye along an incident angle of 10-20°. Moreover, we calculated the filling factors inside the 2DPRG with effective-medium theory to verify the pillar structure changes. This technique eliminates much of the surface modifications and the secondary immunochemical or enzyme-linked steps that are common in immunoassays. Such films have potential applications as optical biosensors.

  11. Embedded surface relief gratings by a simple method to improve absorption and electrical properties of polymer solar cells.

    Li, Kan; Zhen, Hongyu; Huang, Zhuoyin; Li, Guolong; Liu, Xu


    We demonstrate a simple rubbing hole injection layer (HIL) to form surface relief gratings (SRGs) on the functional layers of polymer solar cells (PSCs). PSCs studied in this work consist of an ITO/PEDOT:PSS(HIL)/P3HT:PCBM(photoactive layer)/LiF/Al structure. SRGs are successfully formed on HIL in an effective rubbing process, and are over printed on the photoactive layer and cathode consequently. These triplet SRGs change the morphologies of interfaces of PSCs, which can increase optical path lengths, interaction between HIL and P3HT chains, and interface areas between electrode and photoactive layer. Both light trapping and electrical improvement are confirmed by theory and experiments, which lead to overall increase in short-circuit current density, fill factor, and power conversion efficiency (PCE) of PSCs. An average PCE of 3.8% is achieved from PSCs with SRGs without thermal annealing. Different from the directly rubbing the donor polymer film, a suitable degree of orientation of P3HT presents a lower dichroic ratio and higher photovoltaic response in our work.

  12. Status of ART-XC/SRG Instrument

    Pavlinsky, M.; Akimov, V.; Levin, V.; Lapshov, I.; Tkachenko, A.; Semena, N.; Buntov, M.; Glushenko, A.; Arefiev, V.; Yaskovich, A.; Sunyaev, R.; Churazov, E.; Gilfanov, M.; Grebenev, S.; Sazonov, S.; Revnivtsev, M.; Lutovinov, A.; Molkov, S.; Kudelin, M.; Drozdova, T.; Garanin, S.; Grigorovich, S.; Litvin, D.; Lazarchuk, V.; Roiz, I.; Garin, M.; Babyshkin, V.; Lomakin, I.; Menderov, A.; Moskvinov, D.; Gubarev, M.; Ramsey, B.; Kilaru, K.; ODell, S. L.; Kolodziejczak, J.; Elsner, R.


    Spectrum Roentgen Gamma (SRG) is an X-ray astrophysical observatory, developed by Russia in collaboration with Germany. The mission will be launched in March 2016 from Baikonur, by a Zenit rocket with a Fregat booster and placed in a 6-month-period halo orbit around L2. The scientific payload consists of two independent telescopes - a soft-x-ray survey instrument, eROSITA, being provided by Germany and a medium-x-ray-energy survey instrument ART-XC being developed by Russia. ART-XC will consist of seven independent, but co-aligned, telescope modules. The NASA Marshall Space Flight Center (MSFC) is fabricating the flight mirror modules for the ART-XC/SRG. Each mirror module will be aligned with a focal plane CdTe double-sided strip detectors which will operate over the energy range of 6-30 keV, with an angular resolution of less than 1', a field of view of approximately 34' and an expected energy resolution of about 10 percent at 14 keV.


    ZhuXuezhong; LiuDiji; GuiXiaojie; LiuChuang


    A onvel current chopping strategy for switched reluc-tance generator(SRG)-a full conducted current chopping(FCCC)scheme is presented,According to characteristics lf phase current wave of SRG generating operation,it can be generated under sensorless condition without an addi-tional circuit or a position signal algorithm.Simulational results show the feasibility of this scheme.Experimental results of a 6kW6/4configuration SRG show its simplic-ity and high reliability with little decrease in efficiency.Soit will be widely used.

  14. The infrared limit of the SRG evolution and Levinson's theorem

    Arriola, E. Ruiz; Szpigel, S.; Timóteo, V. S.


    On a finite momentum grid with N integration points pn and weights wn (n = 1 , … , N) the Similarity Renormalization Group (SRG) with a given generator G unitarily evolves an initial interaction with a cutoff λ on energy differences, steadily driving the starting Hamiltonian in momentum space Hn,m0 = pn2 δn,m +Vn,m to a diagonal form in the infrared limit (λ → 0), Hn,mG, λ → 0 =E π (n)δn,m, where π (n) is a permutation of the eigenvalues En which depends on G. Levinson's theorem establishes a relation between phase-shifts δ (pn) and the number of bound-states, nB, and reads δ (p1) - δ (pN) =nB π. We show that unitarily equivalent Hamiltonians on the grid generate reaction matrices which are compatible with Levinson's theorem but are phase-inequivalent along the SRG trajectory. An isospectral definition of the phase-shift in terms of an energy-shift is possible but requires in addition a proper ordering of states on a momentum grid such as to fulfill Levinson's theorem. We show how the SRG with different generators G induces different isospectral flows in the presence of bound-states, leading to distinct orderings in the infrared limit. While the Wilson generator induces an ascending ordering incompatible with Levinson's theorem, the Wegner generator provides a much better ordering, although not the optimal one. We illustrate the discussion with the nucleon-nucleon (NN) interaction in the S10 and S31 channels.

  15. Three Dimensional SRG Evolution of the NN Interactions Using Picard Iteration

    Hadizadeh M. R.


    Full Text Available The Similarity Renormalization Group (SRG evolution of nucleon-nucleon (NN interactions is calculated directly as function of momentum vectors for realistic potentials. To overcome the stiffness of the SRG flow equations in differential form for far off diagonal matrix elements, the differential equation is transformed to an integral form without employing a partial wave decomposition.

  16. Identification of a Novel Gene SRG4 Expressed at Specific Stages of Mouse Spermatogenesis

    Xiao-Wei XING; Lu-Yun LI; Gang LIU; Jun-Jiang FU; Xiao-Jun TAN; Guang-Xiu LU


    Spermatogenesis is a complex process. Two spermatocytes expression sequence tags (ESTs)BG101130 and BG100990 were found. Their putative amino acid sequences have high homology with rat Spag4 (sperm antigen 4). By electrical hybridization, a novel cDNA encoding polypeptide of 348 amino acid residues was identified from a mouse testis cDNA library. The new gene was designated as SRG4(Spermatogenesis related gene 4) (GenBank accession No. AY307077). Results of Northern blot and RT-PCR revealed that SRG4 expressed specifically in mouse testis. Changes of SRG4 expression in mouse dif-ferent development stages were observed by RT-PCR. The SRG4 mRNA was hardly detected in 2 weeks postpartum, and expressed abundantly from 3 weeks later, reaching top lever at 4-5 weeks, while slightly down in aging mouse testis. Results of in situ hybridization showed that SRG4 gene expressed abundantly in spermatocytes, round spermatids. This indicated SRG4 gene may play an important role in mouse meiotic divisions of spermatocytes.

  17. 非匀幅光束在浮雕光栅中的传输特性%Propagation of TE Linear Polarized Super Gaussian Beams Through the Triangle Relief Grating

    王朴; 张丽娟; 李建龙


    利用角谱表示和"逆规则"傅里叶模式理论,研究了非匀幅光束的典型代表TE线偏振高斯光束在亚波长三角形面型浮雕光栅体内的传输.数值分析表明浮雕层内不同透射深度处的光强分布随着透射深度的变化而变化.最后讨论了入射角、周期等光学参数对出射光强分布的影响.这些结论对高衍射效率亚波长光栅的制作和高功率激光光学元件设计等都具有现实意义.%Based on the angular spectrum representation and the "inverse rule" Fourier mode theory, the propagation of the super Gaussian beam through the sub-wavelength triangle relief grating is studied. Numerical calculation shows that the distribution of intensity in different penetration depths changes with the penetration depth in the relief layer. The article also discusses the effects of incident angle, period and other optical parameters on the distribution of the outgoing light intensity.

  18. The ART-XC Instrument on Board the SRG Mission

    Pavlinksy, M.; Akimov, V.; Levin, V.; Lapshov, I.; Tkachenko, A.; Semena, N.; Buntov, M.; Glushenko, A.; Arefiev, V.; Yaskovish, A.; Sunyaeve, R.; Churazov, E.; Sazonov, S.; Revnivtsev, M.; Lutovinov, A.; Molkov, S.; Kudelin, M.; Garanin, S.; Grigorovich, S.; Litvin, D.; Gubarev, M.; Ramsey, B.; Kilaru, K.; ODell, S. L.; Elsner, R.


    Spectrum Roentgen Gamma (SRG) is an X-ray astrophysical observatory, developed by Russia in collaboration with Germany. The mission will be launched in 2014 from Baikonur, by a Zenit rocket with a Fregat booster and placed in a 6-month-period halo orbit around L2. The scientific payload consists of two independent telescopes . a soft-x-ray survey instrument, eROSITA, being provided by Germany and a medium-x-ray-energy survey instrument ART-XC being developed by Russia. ART-XC will consist of seven independent, but co-aligned, telescope modules with seven corresponding cadmium-telluride focal plane detectors. Each will operate over the approximate energy range of 6- 30 keV, with an angular resolution of <1 ', a field of view of 30 ' and an energy resolution about 10% at 14 keV. The NASA Marshall Space Flight Center (MSFC) will fabricate some of the mirror modules, to complement others fabricated by VNIIEF in Russia.

  19. Integral Method for Gratings

    Maystre, Daniel


    The chapter contains a detailed presentation of the surface integral theory for modelling light diffraction by surface-relief diffraction gratings having a one-dimensional periodicity. Several different approaches are presented, leading either to a single integral equation, or to a system of coupled integral equations. Special attention is paid to the singularities of the kernels, and to different techniques to accelerate the convergence of the numerical computations. The theory is applied to gratings having different profiles with or without edges, to real metal and dielectrics, and to perfectly conducting substrates.

  20. Spherical grating spectrometers

    O'Donoghue, Darragh; Clemens, J. Christopher


    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.

  1. Observations of GRB X-ray afterglows with SODART/SRG

    Brandt, Søren Kristian; Lund, Niels; Pedersen, Henrik


    Despite recent progress with the detection of afterglows of Gamma Ray Bursts (GRBs), the nature of these events is unknown. However, important clues to understanding what the GRBs are, may very well be found by studying the X-ray afterglows. The combination on SRG of the MOXE all-sky monitor...

  2. Prospects for AGN Science using the ART-XC on the SRG Mission

    Swartz, Douglas A.; Elsner, Ronald F.; Gubarev, Mikhail V.; O'Dell, Stephen L.; Ramsey, Brian D.; Bonamente, Massimiliano


    The enhanced hard X-ray sensitivity provided by the Astronomical Roentgen Telescope to the Spectrum Roentgen Gamma mission facilitates the detection of heavily obscured and other hard-spectrum cosmic X-ray sources. The SRG all-sky survey will obtain large, statistically-well-defined samples of active galactic nuclei (AGN) including a significant population of local heavily-obscured AGN. In anticipation of the SRG all-sky survey, we investigate the prospects for refining the bright end of the AGN luminosity function and determination of the local black hole mass function and comparing the spatial distribution of AGN with large-scale structure defined by galaxy clusters and groups. Particular emphasis is placed on studies of the deep survey Ecliptic Pole regions.

  3. Fixed points of the SRG evolution and the on-shell limit of the nuclear force

    Arriola, E Ruiz; Timoteo, V S


    We study the infrared limit of the similarity renormalization group (SRG) using a simple toy model for the nuclear force aiming to investigate the fixed points of the SRG evolution with both the Wilson and the Wegner generators. We show how a fully diagonal interaction at the similarity cutoff $\\lambda \\rightarrow 0$ may be obtained from the eigenvalues of the hamiltonian and quantify the diagonalness by means of operator norms. While the fixed points for both generators are equivalent when no bound-states are allowed by the interaction, the differences arising from the presence of the Deuteron bound-state can be disentangled very clearly by analyzing the evolved interactions in the infrared limit $\\lambda \\to 0$ on a finite momentum grid. Another issue we investigate is the location on the diagonal of the hamiltonian in momentum-space where the SRG evolution places the Deuteron bound-state eigenvalue once it reaches the fixed point. This finite momentum grid setup provides an alternative derivation of the ce...

  4. ART-XC/SRG: Status of the X-ray Optics Development

    Gubarev, M.; Ramsey, B.; Elsner, R.; O'Dell, S.; Kolodziejczak, J.; McCracken, J.; Zavlin, V.; Swartz, D.; Kilaru, K.; Atkins, C.; Pavlinskiy, M.; Tkachenko, A.; Lapshov, I.


    The Astronomical Roentgen Telescope (ART) instrument is a hard-x-ray instrument with energy response up to 30 keV that is to be launched on board of the Spectrum Roentgen Gamma (SRG) Mission. The instrument consists of seven identical mirror modules coupled with seven CdTe strip focal-plane detectors. The mirror modules are being developed at the Marshall Space Flight Center (MSFC.) Each module has approximately 65 sq. cm effective area and an on-axis angular resolution of 30 arcseconds half power diameter (HPD) at 8 keV. The current status of the mirror module development and testing will be presented.

  5. Cloning and Characterization of a Novel Gene SRG-L Expressed in Late Stages of Mouse Spermatogenic Cells

    Rui GUO; Peng-Peng MA; Jing MA; Ye-Hua GE; She-Pu XUE; Dai-Shu HAN


    A cDNA expressed specifically in late stages ofmouse spermatogenic cells during spermato-genesis was cloned by using overlapping RT-PCR and RACE. The cDNA contained an open reading frame(ORF) of 2625 base pairs that encoded an 874 amino acids protein. Comparison analysis of amino acidsequence showed 91% and 80% identity to a rat homologue XP-226242 and a monkey homologue BAB63115 respectively. The expression of the mRNA was only observed in pachytene spermatocytes, round, and elongating spermatids. We named this gene as SRG-L (spermatogenesis related gene expressed in the latestages of spermatogenic cells, GenBank accession No. AY352586). The tissue-specific analysis showed that the SRG-L was highly expressed in spleen and testis. The results suggested that SRG-L might play special roles during spermatogenesis, particularly related to meiosis and spermiogenesis. Analysis of the amino acid sequence showed there was a coiled-coil region near the N-terminal region and rich phosphorylation sites,suggesting SRG-L might function as a transmembrane protein mediating signal transduction. This study also demonstrated that gene cloning by RT-PCR was applicable and convenient when its homologous gene wasknown.

  6. Depth relief

    Kappers, A.M.L.; Koenderink, J.J.; Doorn, A.J. van


    A study is reported of the depth relief in a simple three-dimensional scene consisting of a white, rough sphere on a planar support, illuminated in a natural manner. Viewing conditions included monocular and binocular as well as 'synoptical' viewing. In the synoptical condition the eyes are

  7. 3D FE Analysis of RC Beams Externally Strengthened with SRG/SRP Systems

    Francesco Bencardino


    Full Text Available The purpose of this study is to evaluate, through a nonlinear Finite Element (FE analysis, the structural behavior of Reinforced Concrete (RC beams externally strengthened by using Steel Reinforced Grout (SRG and Steel Reinforced Polymer (SRP systems. The parameters taken into account were the external strengthening configuration, with or without U-wrap end anchorages, as well as the strengthening materials. The numerical simulations were carried out by using a three-dimensional (3D FE model. The linear and nonlinear behavior of all materials was modeled by appropriate constitutive laws and the connection between concrete substrate and external reinforcing layer was simulated by means of cohesive surfaces with appropriate bond-slip laws. In order to overcome convergence difficulties, to simulate the quasi-static response of the strengthened RC beams, a dynamic approach was adopted. The numerical results in terms of load-displacement curves, failure modes, and load and strain values at critical stages were validated against some experimental data. As a result, the proposed 3D FE model can be used to predict the structural behavior up to ultimate stage of similar strengthened beams without carrying out experimental tests.

  8. Epoxy Adhesives for Stator Magnet Assembly in Stirling Radioisotope Generators (SRG)

    Cater, George M.


    analysis was done as a function of cure time and temperatures. Adhesion bond strength was tested at various temperatures with lap shear samples using Hiperco 50 substrate to ensure that the proper adhesive is being used. To try and solve the problem of bondline thickness, micro glass beads of 0.0017" in diameter were investigated to see if any other physical properties of the epoxy were affected. Efforts will be made to develop a standard, optimized, fabrication process/procedure of sub-scale magnet-stator assemblies for various adhesive performance evaluation studies under simulated generator conditions. Also, accelerated aging testing will be done in a pressurized canister with stator assembly samples for three years to verify if any degassing or thermal degradation of the epoxy occurs. The necessity of verifying the correct epoxy adhesive system for the stator magnet in the SRG is crucial because failure of the stator assembly would jeopardize the electrical system, and thereby the entire mission itself. My work involves specimen fabrications, testing, and data analyses of the epoxy adhesive system for the stator magnet in the SRG is crucial because failure of the stator assembly would jeopardize the electrical system, and thereby the entire mission itself.

  9. Ubiquitous Over-Expression of Chromatin Remodeling Factor SRG3 Ameliorates the T Cell-Mediated Exacerbation of EAE by Modulating the Phenotypes of both Dendritic Cells and Macrophages.

    Lee, Sung Won; Park, Hyun Jung; Jeon, Sung Ho; Lee, Changjin; Seong, Rho Hyun; Park, Se-Ho; Hong, Seokmann


    Although SWI3-related gene (SRG3), a chromatin remodeling factor, is critical for various biological processes including early embryogenesis and thymocyte development, it is unclear whether SRG3 is involved in the differentiation of CD4+ T cells, the key mediator of adaptive immune responses. Because it is known that experimental autoimmune encephalomyelitis (EAE) development is determined by the activation of CD4+ T helper cells, here, we investigated the role of SRG3 in EAE development using SRG3 transgenic mouse models exhibiting two distinct SRG3 expression patterns: SRG3 expression driven by either the CD2 or β-actin promoter. We found that the outcome of EAE development was completely different depending on the expression pattern of SRG3. The specific over-expression of SRG3 using the CD2 promoter facilitated EAE via the induction of Th1 and Th17 cells, whereas the ubiquitous over-expression of SRG3 using the β-actin promoter inhibited EAE by promoting Th2 differentiation and suppressing Th1 and Th17 differentiation. In addition, the ubiquitous over-expression of SRG3 polarized CD4+ T cell differentiation towards the Th2 phenotype by converting dendritic cells (DCs) or macrophages to Th2 types. SRG3 over-expression not only reduced pro-inflammatory cytokine production by DCs but also shifted macrophages from the inducible nitric oxide synthase (iNOS)-expressing M1 phenotype to the arginase-1-expressing M2 phenotype during EAE. In addition, Th2 differentiation in β-actin-SRG3 Tg mice during EAE was associated with an increase in the basophil and mast cell populations and in IL4 production. Furthermore, the increased frequency of Treg cells in the spinal cord of β-actin-SRG3 Tg mice might induce the suppression of and accelerate the recovery from EAE symptoms. Taken together, our results provide the first evidence supporting the development of a new therapeutic strategy for EAE involving the modulation of SRG3 expression to induce M2 and Th2 polarization

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

    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.


    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.

  11. ART-XC/SRG: results of qualification thermo-vacuum tests

    Semena, N.; Pavlinsky, M.; Buntov, M.; Serbinov, D.; Levin, V.; Tambov, V.; Rotin, A.; Krivchenko, A.


    ART-XC - a medium-x-ray-energy survey instrument of "Spectrum-Roentgen-Gamma" (SRG) project is being developed in Russia under the leadership of the Space Research Institute (IKI). Main requirements to the telescope temperature control system are provided by two key elements - module of seven semiconductor DSSD CdTe detectors which have to operate at the temperature -22.5+/-2.5 °C to prevent CdTe crystals fast polarization (large polarization time allows to keep detector energy spectral characteristics during continuous 2 - 3 days expositions) and the module of seven mirror systems which have to operate at a temperature 20+/-2 °C (which is the temperature used in the on Earth mirror systems calibration tests).Thermal control system ART-XC consists of 36 tunable film heaters placed in different places on the telescope structure and controlled according to indications of thermal sensors. The maximum power of each heater is 10 W. There are 21 heaters located on seven mirror systems. Each mirror system case is equipped with two heaters, additional one is located on the mirror system baffle. Seven heaters are placed on detectors. Remaining eight heaters are placed in different telescope parts - one on the protective cover, one on the explosive pin, one under the star tracker, three on the mirror system and star tracker mount plate, one on the detector block mount plate and one on the calibration sources control system block. Thermal control system constantly checks temperature from 36 thermal sensors and regulate the heater's power supply. There is one passive thermal control element in the telescope - radiator, which is connected to detectors via three heat pipes and cools them down. The QM (qualification model) of ART-XC was manufacture and tested. QM completely corresponds to flight model. Conditions of thermo-vacuum tests were corresponded to real external thermal conditions in flight. The vacuum, cold of space, temperature of mounting planes and shielding by e

  12. Direct Magnetic Relief Recording Using As40S60: Mn-Se Nanocomposite Multilayer Structures.

    Stronski, A; Achimova, E; Paiuk, O; Meshalkin, A; Prisacar, A; Triduh, G; Oleksenko, P; Lytvyn, P


    Processes of holographic recording of surface relief structures using As2S3:Mn-Se multilayer nanostructures as registering media were studied in this paper. Optical properties of As2S3:Mn, Se layers, and As2S3:Mn-Se multilayer nanostructures were investigated. Values of optical bandgaps were obtained from Tauc dependencies. Surface relief diffraction gratings were recorded. Direct one-stage formation of surface relief using multilayer nanostructures is considered. For the first time, possibility of direct formation of magnetic relief simultaneous with surface relief formation under optical recording using As2S3:Mn-Se multilayer nanostructures is shown.

  13. Itching for Allergy Relief?

    ... Home For Consumers Consumer Updates Itching for Allergy Relief? Share Tweet Linkedin Pin it More sharing options ... your ability to function, you don't find relief from OTC drugs, or you experience allergy symptoms ...

  14. Novel diffraction gratings for next generation spectrographs with high spectral dispersion

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


    As a transmission grating, a surface-relief (SR) grating with sawtooth shaped ridges and volume phase holographic (VPH) grating are widely used for instruments of astronomical observations. However the SR grating is difficult to achieve high diffraction efficiency at high angular dispersion, and the VPH grating has low diffraction efficiency in high diffraction orders. We propose novel gratings that solve these problems. We introduce the hybrid grism which combines a high refractive index prism with a replicated transmission grating, which has sawtooth shaped ridges of an acute apex angle. The birefringence VPH (B-VPH) grating which contains an anisotropic medium, such as a liquid crystal, achieves diffraction efficiency up to 100% at the first diffraction order for natural polarization and for circular polarization. The quasi-Bragg (QB) grating which consists of long rectangular mirrors aligned in parallel precisely, like a window blind, achieves diffraction efficiency of 60% or more in higher than the 4th diffraction order. The volume binary (VB) grating with narrow grooves also achieves diffraction efficiency of 60% or more in higher than the 6th diffraction order. The reflector facet transmission (RFT) grating which is a SR grating with sawtooth shaped ridges of an acute apex angle achieves diffraction efficiency up to 80% in higher than the 4th diffraction order.

  15. History of grating images

    Iwata, Fujio


    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.

  16. Grating image technology

    Iwata, Fujio


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

  17. An elastomeric grating coupler

    Kocabas, A.; Ay, F.; Dana, A.; Aydinli, A.


    We report on a novel nondestructive and reversible method for coupling free space light to planar optical waveguides. In this method, an elastomeric grating is used to produce an effective refractive index modulation on the surface of the optical waveguide. The external elastomeric grating binds to

  18. Bragg gratings in Topas

    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...

  19. Ginsenoside 20(S-Rg3 targets HIF-1α to block hypoxia-induced epithelial-mesenchymal transition in ovarian cancer cells.

    Ting Liu

    Full Text Available The prognosis of patients with ovarian cancer has remained poor mainly because of aggressive cancer progression. Since epithelial-mesenchymal transition (EMT is an important mechanism mediating invasion and metastasis of cancer cells, targeting the EMT process with more efficacious and less toxic compounds to inhibit metastasis is of great therapeutic value for the treatment of ovarian cancer. We have found for the first time that the ginsenoside 20(S-Rg3, a pharmacologically active component of the traditional Chinese herb Panax ginseng, potently blocks hypoxia-induced EMT of ovarian cancer cells in vitro and in vivo. Mechanistic studies confirm the mode of action of 20(S-Rg3, which reduces the expression of hypoxia-inducible factor 1α (HIF-1α by activating the ubiquitin-proteasome pathway to promote HIF-1α degradation. A decrease in HIF-1α in turn leads to up-regulation, via transcriptional suppression of Snail, of the epithelial cell-specific marker E-cadherin and down-regulation of the mesenchymal cell-specific marker vimentin under hypoxic conditions. Importantly, 20(S-Rg3 effectively inhibits EMT in nude mouse xenograft models of ovarian cancer, promising a novel therapeutic agent for anticancer therapy.

  20. Menopause: Symptom Relief and Treatments

    ... Submit Home > Menopause > Menopause symptom relief and treatments Menopause Menopause symptom relief and treatments Working with your doctor ... on menopause symptom relief and treatments Learning about menopause treatment options Most women do not need treatment ...

  1. Adjustable safety relief valve

    Taylor, W.L.


    This patent describes a pressure relief valve having a relief set pressure. It comprises: a valve body having a fluid inlet and outlet, a spherical, metal valve seat associated with the inlet and a valve member comprising at least a portion of a spherical,metal ball attached to a ball holding element, the valve member being biased against the valve seat and thus providing a metal-to-metal seal preventing the passage of fluids past the valve seat when the fluid pressure in the inlet is below the relief pressure setting of the valve.

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

    Sudheer, Porwal, S.; Bhartiya, S.; Rao, B. T.; Tiwari, P.; Srivastava, Himanshu; Sharma, T. K.; Rai, V. N.; Srivastava, A. K.; Naik, P. A.


    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.

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

    Sudheer,, E-mail:, E-mail:; 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)


    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.

  4. Reflective three-port high-efficiency grating with two dielectric layers based on a sandwiched configuration

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


    In this paper, we describe a novel reflective sandwiched three-port grating with two dielectric layers. The two-layer sandwiched grating can separate incident wave into the ± 1 and the 0th-order with high-efficiency beam splitting and good splitting ratios for both transverse electric (TE) and transverse magnetic (TM) polarizations. The grating parameters can be optimized by using rigorous coupled-wave analysis (RCWA) with a special duty cycle of 0.6. With the optimized results, efficiencies more than 32% in the ± 1st-orders and the 0th-order can be obtained. Furthermore, performance of the incident bandwidth and aspect ratio can be improved. Compared with conventional surface-relief grating, the grating with sandwiched structure is aimed at cleaning and protecting grating surface. The presented reflective two-layer sandwiched three-port grating would be put into practical applications for its beneficial performances.

  5. Optically inscribed surface-relief zone plates in azo polymer films

    Jun Yang; Bin Guo; Douguo Zhang; Pei Wang; Hai Ming


    We describe a simple and cost-effective holographic method for the fabrication of surface-relief zone plates.The zone plate is inscribed by interference between the first- and second-order diffracted waves from an ionetched Fresnel zone plate. The inscribed surface-relief zone plates are observed by atomic force microscope (AFM). The formation process of the surface grating and the mass diffusion in azo polymer are analyzed.

  6. Gratings in polymeric waveguides

    Mishakov, G.; Sokolov, V.; Kocabas, A.; Aydinli, A.


    Laser-induced formation of polymer Bragg grating filters for Dense Wavelength Division Multiplexing (DWDM) applications is discussed. Acrylate monomers halogenated with both fluorine and chlorine, which possess absorption losses less than 0.25 dB/cm and wide choice of refractive indices (from 1.3 to 1.5) in the 1.5 μm telecom wavelength region were used. The monomers are highly intermixable thus permitting to adjust the refractive index of the composition within +/-0.0001. Moreover they are photocurable under UV exposure and exhibit high contrast in polymerization. These properties make halogenated acrylates very promising for fabricating polymeric waveguides and photonic circuits. Single-mode polymer waveguides were fabricated on silicon wafers using resistless contact lithography. Submicron index gratings have been written in polymer waveguides using holographic exposure with He-Cd laser beam (325 nm) through a phase mask. Both uniform and apodized gratings have been fabricated. The gratings are stable and are not erased by uniform UV exposure. The waveguide gratings possess narrowband reflection spectra in the 1.5 μm wavelength region of 0.4 nm width, nearly rectangular shape of the stopband and reflectivity R > 99%. The fabricated Bragg grating filters can be used for multiplexing/demultiplexing optical signals in high-speed DWDM optical fiber networks.

  7. One-step photoembossing for submicrometer surface relief structures in liquid crystal semiconductors.

    Liedtke, Alicia; Lei, Chunhong; O'Neill, Mary; Dyer, Peter E; Kitney, Stuart P; Kelly, Stephen M


    We report a new single-step method to directly imprint nanometer-scale structures on photoreactive organic semiconductors. A surface relief grating is spontaneously formed when a light-emitting, liquid crystalline, and semiconducting thin film is irradiated by patterned light generated using a phase mask. Grating formation requires no postannealing nor wet etching so there is potential for high-throughput fabrication. The structured film is cross-linked for robustness. Gratings deeper than the original film thickness are made with periods as small as 265 nm. Grating formation is attributed to mass transfer, enhanced by self-assembly, from dark to illuminated regions. A photovoltaic device incorporating the grating is discussed.

  8. Surface relief resonant Brewster filters with multiple with multiple channels

    Ma Jian-Yong; Liu Shi-Jie; Zhang Da-Wei; Yao Jian-Ke; Xu Cheng; Jin Yun-Xia; Shao Jian-Da; Fan Zheng-Xiu


    In this paper,a new type of resonant Brewster filters(RBF)with surface relief structure for the multiple channels is first presented by using the rigorous coupled-wave analysis and the S-matrix method.By tuning the depth of homogeneous layer which is under the surface relief structure,the multiple channels phenomenon is obtained.Long range,extremely low sidebands and multiple channels are found when the RBF with surface relief structure is illuminated with Transverse Magnetic incident polarization light near the Brewster angle calculated with the effective media theory of sub wavelength grating.Moreover,the wavelengths of RBF with surface relief structure can be easily shifted by changing the depth of homogeneous layer while its optical properties such as low sideband reflection and narrow band are not spoiled when the depth is changed.Furthermore,the variation of the grating thickness does not effectively change the resonant wavelength of RBF,but have a remarkable effect on its line width,which is very useful for designing such filters with different line widths at desired wavelength.

  9. Efficient IR Transmission Diffraction Grating for Circularly Polarized Light

    Cole, Helen; Chambers, Diana


    Numerical methods, using rigorous coupled wave theory, are used to design rectangular relief diffraction gratings for an infrared application which requires comparable first order efficiencies in the TE and TM polarization states. The depth, period, and fill factor of the grating are varied to identify optimal two level binary lamellar grating profiles which predict efficiencies for individual TM and TE polarizations above 75 percent, while keeping the difference between the two efficiencies within 10 percent. The application at hand is a rotating, transmissive diffractive scanner for space-based coherent lidar. The operating wavelength is 2.0 microns. A collimated, circularly polarized beam is incident on the diffractive scanner at the Bragg angle; 30 and 45 degree beam deflection angles being studied. Fused silica is the substrate material of choice. Selected designs are fabricated on 3 inch fused silica substrates using lithographic methods. The performance of the test pieces is measured and compared to theoretical predictions.

  10. Polymer gratings based on photopolymerization for low-order distributed feedback polymer lasers

    Xuanke Zhao; Qingwu Zhao; Qinghua Zhang


    Novel polymer distributed feedback(DFB)gratings are fabricated based on photopolymerization to reduce lasing threshold of polymer lasers.A photopolymer formulation sensitive to 355-nm ultraviolet(UV)light is proposed for the fabrication of polymer gratings and it can be used to form polymer films by spin-coating process.A very low surface-relief depth ranging from 12.5 to about 1.0 nm has been demonstrated with a refractive-index modulation of about 0.012.The experimental results indicate that such polymer gratings have promising potentials for the fabrication of low-order DFB organic semiconductor lasers.

  11. Microstructure of Reflection Holographic Grating Inscribed in an Absorptive Azopolymer Film

    Choi, Hyunhee


    Microstructure of reflection holographic grating fabricated via a photo-isomerization process in an absorptive azopolymer film is analyzed. A surface relief formation takes place on the film surface even in the reflection holographic configuration. The polarization-dependent diffraction efficiency and the polarization analysis reveal that the polarization grating structure inside the film strongly depends on the amount of optical absorption experienced by the two writing beams. Theoretical analysis shows that the reflection polarization grating, while mimicking a cholesteric liquid crystal structure, is composed of elliptic polarizations with the ellipticity going through a periodic modulation.

  12. Azopolymer film as an actuator for organizing multiwall carbon nanotubes

    Capeluto, Maria Gabriela; Fernández Salvador, Raquel; Eceiza, Aranxa; Goyanes, Silvia; Ledesma, Silvia Adriana


    In this work we show the feasibility of using an azopolymer as an actuator to induce nano- and microscale movements controlled with light from the far field. We study azopolymers and their interaction with multi-walled carbon nanotubes (MWCNTs) by inducing surface relief gratings (SRG) through optical illumination. Upon different optical treatments, the MWCNTs are organized in the troughs or the crests of a surface relief grating. Large scale organization of MWCNTs has potential in applications such as transparent electronics.

  13. Ultra-High Temperature Gratings

    John Canning; Somnath Bandyopadhyay; Michael Stevenson; Kevin Cook


    Regenerated gratings seeded by type-Ⅰ gratings are shown to withstand temperatures beyond 1000 ℃. The method of regeneration offers a new approach to increasing temperature resistance of stable fibre Bragg and other gratings. These ultra-high temperature (UHT) gratings extend the applicability of silicate based components to high temperature applications such as monitoring of smelters and vehicle and aircraft engines to high power fibre lasers.

  14. An elastomeric grating coupler

    Kocabas, Askin; Ay, Feridun; Dâna, Aykutlu; Aydinli, Atilla


    We report on a novel nondestructive and reversible method for coupling free space light to planar optical waveguides. In this method, an elastomeric grating is used to produce an effective refractive index modulation on the surface of the optical waveguide. The external elastomeric grating binds to the surface of the waveguide with van der Waals forces and makes conformal contact without any applied pressure. As a demonstration of the feasibility of the approach, we use it to measure the refractive index of a silicon oxynitride film. This technique is nondestructive, reversible, low cost and can easily be applied to the characterization of optical materials for integrated optics.

  15. Circular Fibonacci gratings.

    Gao, Nan; Zhang, Yuchao; Xie, Changqing


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

  16. Relief Aid Carefully Audited


    In a recent interview with the national TV broadcaster CCTV,Wang Zhongxin,Director of the Social Security Audit Department at the National Audit Office,talks about the procedures that are in effect to ensure relief supplies for the Wenchuan earthquake victims reach the end users. Excerpts of

  17. Paper relief architecture

    Latka, J.F.


    The article presents two contemporary projects of paper structures relief architecture designed and built by Shigeru Ban Architects and Voluntary Architect Network. Author of the article took part in design and construction process of one of the projects. The project of Yaan Nursery School, which wa

  18. Vent Relief Valve Test


    Shown is the disassembly, examination, refurbishment and testing of the LH2 ( liquid hydrogen) and LOX (liquid oxygen) vent and relief valves for the S-IVB-211 engine stage in support of the Constellation/Ares project. This image is extracted from high definition video and is the highest resolution available.

  19. Allergy Relief for Your Child

    ... For Consumers Home For Consumers Consumer Updates Allergy Relief for Your Child Share Tweet Linkedin Pin it ... counter (OTC) and prescription medicines that offer allergy relief as well as allergen extracts used to diagnose ...

  20. Finding Relief from Allergy's Grip

    ... Navigation Bar Home Current Issue Past Issues Finding Relief from Allergy's Grip Past Issues / Summer 2006 Table ... action for patients who have had inadequate symptom relief with antihistamines and topical nasal steroids. Through injection ...

  1. Sensored fiber reinforced polymer grate

    Ross, Michael P.; Mack, Thomas Kimball


    Various technologies described herein pertain to a sensored grate that can be utilized for various security fencing applications. The sensored grate includes a grate framework and an embedded optical fiber. The grate framework is formed of a molded polymer such as, for instance, molded fiber reinforced polymer. Further, the grate framework includes a set of elongated elements, where the elongated elements are spaced to define apertures through the grate framework. The optical fiber is embedded in the elongated elements of the grate framework. Moreover, bending or breaking of one or more of the elongated elements can be detected based on a change in a characteristic of input light provided to the optical fiber compared to output light received from the optical fiber.

  2. Polarization holographic recording in Disperse Red1 doped polyurethane polymer film

    Aleksejeva, J.; Gerbreders, A.; Gertners, U.; Reinfelde, M.; Teteris, J.


    In this report holographic recording of polarisation and surface relief gratings in Disperse Red 1 (DR1) doped polyurethane polymer films was studied. In this material DR1 is chemically bounded to polyurethane polymer main chain. Polarization holographic recording was performed by two orthogonal circularly polarized 532 nm laser beams. Photoinduced birefringence is a precondition for polarization holograms recording, therefore a detailed study of a photoinduced birefringence and changes of optical properties was performed. The lasers with wavelengths of 375nm, 448nm, 532 nm and 632.8 nm were used as pumping beam for sample excitation. The photoinduced birefringence Δn was measured at 532 nm and 632.8 nm wavelengths. The photoinduced birefringence dependence on the pumping beam wavelength and intensity was investigated. Surface relief grating (SRG) formation was observed during polarization holographic recording process. A profile of SRG was studied by AFM. A relationship between SRG formation and photoinduced birefringence has been discussed.

  3. Bragg grating fiber optic sensing for bridges and other structures

    Measures, Raymond M.; Alavie, A. Tino; Maaskant, Robert; Huang, Shang Yuan; LeBlanc, Michel


    We have demonstrated that fiber optic intracore Bragg grating sensors are able to measure the strain relief experienced over an extended period of time by both steel and carbon composite tendons within the concrete deck support girders of a recently constructed two span highway bridge. This is the first bridge in the world to test the prospects of using carbon fiber composite tendons to replace steel tendons. This unique set of measurements was accomplished with an array of 15 Bragg grating fiber optic sensors that were embedded within the precast concrete girders during their construction. We have also demonstrated that these same sensors can measure the change in the internal strain within the girders associated with both static and dynamic loading of the bridge with a truck. We are now studying the ability of Bragg grating fiber optic sensors to measure strong strain gradients and thereby provide a warning of debonding of any Bragg grating sensor from its host of the most important failure modes for any fiber optic strain sensor.

  4. Applicability of STEM-RTG and High-Power SRG Power Systems to the Discovery and Scout Mission Capabilities Expansion (DSMCE) Study of ASRG-Based Missions

    Colozza, Anthony J.; Cataldo, Robert L.


    This study looks at the applicability of utilizing the Segmented Thermoelectric Modular Radioisotope Thermoelectric Generator (STEM-RTG) or a high-power radioisotope generator to replace the Advanced Stirling Radioisotope Generator (ASRG), which had been identified as the baseline power system for a number of planetary exploration mission studies. Nine different Discovery-Class missions were examined to determine the applicability of either the STEM-RTG or the high-power SRG power systems in replacing the ASRG. The nine missions covered exploration across the solar system and included orbiting spacecraft, landers and rovers. Based on the evaluation a ranking of the applicability of each alternate power system to the proposed missions was made.

  5. Low crosstalk Arrayed Waveguide Grating with Cascaded Waveguide Grating Filter

    Deng Yang; Liu Yuan; Gao Dingshan, E-mail: [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China)


    We propose a highly compact and low crosstalk arrayed waveguide grating (AWG) with cascaded waveguide grating (CWGF). The side lobes of the silicon nanowire AWG, which are normally introduced by fabrication errors, can be effectively suppressed by the CWGF. And the crosstalk can be improved about 15dB.

  6. Phytotherapy for pain relief.

    Zareba, Grazyna


    Pain is considered the third most common healthcare problem disabling more individuals than heart disease and cancer together. Although pharmacological pain management offers a significant relief in several pain-related diseases, many patients turn to its supplementation with complementary and alternative medicine. Botanicals used in pain therapy can contribute to restoring the quality of life to a patient and may effect and enhance conventional pain management. Herbal analgesic use in several pain-related diseases such as rheumatologic diseases, back pain, cancer, diabetic peripheral neuropathy and migraine will be discussed. In addition, this review describes botanicals with known analgesic activity for which randomized, placebo-controlled, double-blind trials assessing their efficacy in different pain-related diseases have been published and which have been recently evaluated in many systematic reviews with well-described methodology.

  7. Stretchable diffraction gratings for spectrometry

    Simonov, A.N.; Grabarnik, S.; Vdovine, G.V


    We have investigated the possibility of using transparent stretchable diffraction gratings for spectrometric applications. The gratings were fabricated by replication of a triangular-groove master into a transparent viscoelastic. The sample length, and hence the spatial period, can be reversibly cha

  8. Picosecond Holographic-Grating Spectroscopy

    Duppen, K.


    Interfering light waves produce an optical interference pattern in any medium that interacts with light. This modulation of some physical parameter of the system acts as a classical holographic grating for optical radiation. When such a grating is produced through interaction of pulsed light waves w

  9. Grating-based red lasers

    Pezeshki, Bardia; Hagberg, Mats; Zelinski, Michael; Zou, Sarah; Kolev, Emil I.


    We have demonstrated a number of high power and single- frequency lasers at 635 - 680 nm by incorporating a grating reflector within the device, including DBRs, tunable DBRs, monolithic MOPAs, DFBs, and angled-grating DFBs. The DBR laser, with an unpumped grating as the rear reflector, is the simplest single-frequency structure, with about 20 mW output power. The device can be tuned about 3 nm by injecting current in the rear grating. Higher output power can be obtained by combining the DBR with a flared amplifier to form a monolithic MOPA with over 250 mW CW output power. Unlike DBR structures, the DFBs have a grating throughout their gain region, and therefore show no mode hops. Wavelengths as short as 634 nm and output powers as high as 90 mW have been obtained with DFBs. An angle-grating DFB is a broad area device where the angled grating forces lasing in a single spatial and longitudinal mode. More than 400 mW in single-frequency power has been obtained at 660 nm from such a structure. In general, grating-based red lasers are useful for interferometry, spectroscopy, and fiber-coupling applications.

  10. Slow plasmons in grating cavities

    Aydinli, Atilla; Karademir, Ertugrul; Balci, Sinan; Kocabas, Coskun


    Recent research on surface plasmon polaritons and their applications have brought forward a wealth of information and continues to be of interest to many. In this report, we concentrate on propagating surface plasmon polaritons (SPPs) and their interaction with matter. Using grating based metallic structures, it is possible to control the electrodynamics of propagating SPPs. Biharmonic gratings loaded with periodic Si stripes allow excitation of SPPs that are localized inside the band gap with grating coupling. The cavity state is formed due to periodic effective index modulation obtained by one harmonic of the grating and loaded Si stripes. More complicated grating structures such as metallic Moiré surfaces have also been shown to form a localized state inside the band gap when excited with Kretschmann configuration.

  11. Waiver Plan Generates Relief, Fret

    Klein, Alyson; McNeil, Michele


    While the Obama administration's plan to offer states relief from parts of the No Child Left Behind (NCLB) Act--if they agree to embrace unspecified education redesign priorities--has drawn kudos from some quarters, it isn't sitting well in others. Officials in a number of states have praised the idea as an opportunity for badly needed relief from…

  12. 24 CFR 965.508 - Individual relief.


    ... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Individual relief. 965.508 Section... relief. Requests for relief from surcharges for excess consumption of PHA-purchased utilities, or from... appropriate. The PHA's criteria for granting such relief, and procedures for requesting such relief, shall be...

  13. Quick-Relief Medications for Lung Diseases

    ... relief medications are used to treat asthma, other lung disease symptoms or an acute episode (such as an ... about the following quick-relief asthma and other lung disease medications: Anticholinergics Anticholinergics are quick-relief asthma and ...

  14. Switchable Bragg gratings

    Marckmann, Carl Johan


    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....... This result is very useful in the production of telecommunication devices since polarization independence of the second-order nonlinearity is wanted. In order to increase the second-order nonlinearity, it was found that the introduction of a high refractive index trapping layer was favorable. During...... the thesis, the thermal poling induced second-order nonlinearity was increased by approximately 64% making a silica based optical switch possible. Finally, a possible explanation to the very high, but short-lived, poling results obtained by some groups was discovered....

  15. Optical Fiber Grating based Sensors

    Michelsen, Susanne


    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...

  16. Extreme Silica Optical Fibre Gratings

    Kevin Cook


    Full Text Available A regenerated optical fibre Bragg grating that survives temperature cycling up to 1,295°C is demonstrated. A model based on seeded crystallisation or amorphisation is proposed.

  17. Southern Alaska Coastal Relief Model

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building coastal-relief models (CRM) for select U.S. coastal regions. Bathymetric, topographic, and shoreline data...

  18. MEMS Bragg grating force sensor

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


    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....

  19. Stretchable diffraction gratings for spectrometry.

    Simonov, Aleksey N; Grabarnik, Semen; Vdovin, Gleb


    We have investigated the possibility of using transparent stretchable diffraction gratings for spectrometric applications. The gratings were fabricated by replication of a triangular-groove master into a transparent viscoelastic. The sample length, and hence the spatial period, can be reversibly changed by mechanical stretching. When used in a monochromator with two slits, the stretchable grating permits scanning the spectral components over the output slit, converting the monochromator into a scanning spectrometer. The spectral resolution of such a spectrometer was found to be limited mainly by the wave-front aberrations due to the grating deformation. A model relating the deformation-induced aberrations in different diffraction orders is presented. In the experiments, a 12-mm long viscoelastic grating with a spatial frequency of 600 line pairs/mm provided a full-width at half-maximum resolution of up to ~1.2 nm in the 580-680 nm spectral range when slowly stretched by a micrometer screw and ~3 nm when repeatedly stretched by a voice coil at 15 Hz. Comparison of aberrations in transmitted and diffracted beams measured by a Shack- Hartmann wave-front sensor showed that astigmatisms caused by stretch-dependent wedge deformation are the main factors limiting the resolution of the viscoelastic-grating-based spectrometer.

  20. Hole-drilling method using grating rosette and Moire interferometry

    Jubing Chen; Yongsheng Peng; Shexu Zhao


    The hole-drilling method is one of the most well-known methods for measuring residual stresses. To identify unknown plane stresses in a specimen, a circular hole is first drilled in the infinite plate under plane stress, then the strains resulting from the hole drilling is measured. The strains may be acquired from interpreting the Moire signature around the hole. In crossed grating Moire interferometry, the horizontal and vertical displacement fields (u and v) can be obtained to determinate two strain fields and one sheafing strain field. In this paper, by means of Moire interferometry and three directions grating (grating rosette) developed by the authors, three displacement fields (u, v and s) are obtained to acquire three strain fields. As a practical application, the hole-drilling method is adopted to measure the relief strains for aluminum and fiber reinforced composite. It is a step by step method; in each step a single laminate or equivalent depth is drilled to find some relationships between the drilling depth and the residual strains relieved in the fiber reinforced composite materials.

  1. 7 CFR 760.106 - Equitable relief.


    ... 7 Agriculture 7 2010-01-01 2010-01-01 false Equitable relief. 760.106 Section 760.106 Agriculture... Assistance Programs § 760.106 Equitable relief. (a) The Secretary may provide equitable relief on a case-by... accordance with the FCIA (7 U.S.C. 1501-1524) or (ii) Application closing date for NAP. (b) Equitable relief...

  2. Efficient iterative technique for designing bragg gratings

    Plougmann, Nikolai; Kristensen, Martin


    We present a new iterative method for designing Bragg gratings based on the Levenberg-Marquardt method of minimizing a chi-squared merit function. It is effective for designing both weak and strong gratings and is particularly well suited for unchirped gratings.......We present a new iterative method for designing Bragg gratings based on the Levenberg-Marquardt method of minimizing a chi-squared merit function. It is effective for designing both weak and strong gratings and is particularly well suited for unchirped gratings....

  3. Finite-number-of-periods holographic gratings with finite-width incident beams: analysis using the finite-difference frequency-domain method

    Wu, Shun-Der; Glytsis, Elias N.


    The effects of finite number of periods (FNP) and finite incident beams on the diffraction efficiencies of holographic gratings are investigated by the finite-difference frequency-domain (FDFD) method. Gratings comprising 20, 15, 10, 5, and 3 periods illuminated by TE and TM incident light with various beam sizes are analyzed with the FDFD method and compared with the rigorous coupled-wave analysis (RCWA). Both unslanted and slanted gratings are treated in transmission as well as in reflection configurations. In general, the effect of the FNP is a decrease in the diffraction efficiency with a decrease in the number of periods of the grating. Similarly, a decrease in incident-beam width causes a decrease in the diffraction efficiency. Exceptions appear in off-Bragg incidence in which a smaller beam width could result in higher diffraction efficiency. For beam widths greater than 10 grating periods and for gratings with more than 20 periods in width, the diffraction efficiencies slowly converge to the values predicted by the RCWA (infinite incident beam and infinite-number-of-periods grating) for both TE and TM polarizations. Furthermore, the effects of FNP holographic gratings on their diffraction performance are found to be comparable to their counterparts of FNP surface-relief gratings. 2002 Optical Society of America

  4. Pressure relief valve/safety relief valve testing

    Murray, W.A.; Hamm, E.R.; Barber, J.R.


    Pressure vessels and piping systems are protected form overpressurization by pressure relief valves. These safety features are required to be tested-inspected on some periodic basis and, in most cases witnessed by a third party inspector. As a result nonconformances found by third parties Westinghouse Hanford Company initiated a task team to develop a pressure safety program. This paper reveals their findings.

  5. Exploiting a Transmission Grating Spectrometer

    Ronald E. Bell


    The availability of compact transmission grating spectrometers now allows an attractive and economical alternative to the more familiar Czerny-Turner configuration for many high-temperature plasma applications. Higher throughput is obtained with short focal length refractive optics and stigmatic imaging. Many more spectra can be obtained with a single spectrometer since smaller, more densely packed optical input fibers can be used. Multiple input slits, along with a bandpass filter, can be used to maximize the number of spectra per detector, providing further economy. Curved slits can correct for the strong image curvature of the short focal length optics. Presented here are the governing grating equations for both standard and high-dispersion transmission gratings, defining dispersion, image curvature, and desired slit curvature, that can be used in the design of improved plasma diagnostics.

  6. High Efficiency Low Scatter Echelle Grating Project

    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...

  7. Polymer optical fiber bragg grating sensors

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


    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....

  8. A Composite Grating for Moire Interferometry.


    shown in Figure 7 in which two virtual reference gratings of frequencies 2400 and 600 lines/mm were used. This arrangement corresponds to a fringe...fields at the two virtual reference grating frequencies of 2400/600 lines/mm. The light paths of the two virtual reference gratings are controlled by...frequencies were selectively recorded. Figure 10 and 11 shows two moire fringe patterns for virtual reference grating frequencies of 2400 lines/mm and 600

  9. Fabrication of Polymer Optical Fibre (POF Gratings

    Yanhua Luo


    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.

  10. Grating-Coupled Waveguide Cloaking

    WANG Jia-Fu; QU Shao-Bo; XU Zhuo; MA Hua; WANG Cong-Min; XIA Song; WANG Xin-Hua; ZHOU Hang


    Based on the concept of a grating-coupled waveguide (GCW),a new strategy for realizing EM cloaking is presented.Using metallic grating,incident waves are firstly coupled into the effective waveguide and then decoupled into free space behind,enabling EM waves to pass around the obstacle.Phase compensation in the waveguide keeps the wave-front shape behind the obstacle unchanged.Circular,rectangular and triangular cloaks are presented to verify the robustness of the GCW cloaking.Electric field animations and radar cross section (RCS)comparisons convincingly demonstrate the cloaking effect.

  11. Hybrid grating reflectors: Origin of ultrabroad stopband

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


    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...

  12. 3D Printed Terahertz Focusing Grating Couplers

    Jahn, David; Weidenbach, Marcel; Lehr, Jannik; Becker, Leonard; Beltrán-Mejía, Felipe; Busch, Stefan F.; Balzer, Jan C.; Koch, Martin


    We have designed, constructed and characterized a grating that focuses electromagnetic radiation at specific frequencies out of a dielectric waveguide. A simple theoretical model predicts the focusing behaviour of these chirped gratings, along with numerical results that support our assumptions and improved the grating geometry. The leaky waveguide was 3D printed and characterized at 120 GHz demonstrating its potential for manipulating terahertz waves.

  13. Grating inscription in picosecond regime in thin films of functionalized DNA.

    Czaplicki, R; Krupka, O; Essaidi, Z; El-Ghayoury, A; Kajzar, F; Grote, J G; Sahraoui, B


    Polymers containing azo-benzene groups are useful holographic recording materials. In these materials the efficient mixed amplitude and phase gratings, frequently accompanied with photoinduced-surface relief gratings, can be inscribed with polarized laser light. The light-induced trans-cis-trans photoisomerization of azo-benzene groups is responsible for optical anisotropy in such systems. The aim of the present work is to study the dynamics of grating inscription in Disperse Red 1 doped deoxyrbonucleic acid- hexadecyltrimethylammonium material (DR1-DNACTMA) using 16 ps laser pulses (532 nm, 1.3 mJ). Results are compared with that obtained for other polymeric matrices loaded with DR1. The dynamics of the grating growth, due to repeated pulses from picosecond laser with 10 Hz repetition rate, was probed by measuring the intensity of the first order of diffraction of a cw He-Ne. We report results in function of the light polarization of writing beams. In this paper we present the first results of the grating inscription in functionalized DNA (in the picosecond pulse regime).

  14. Fraktalnist deformational relief polycrystalline aluminum

    М.В. Карускевич


    Full Text Available  The possibility of the fractal geometry method application for the analisys of surface deformation structures under cyclic loading is presented.It is shown, that deformation relief of the alclad aluminium alloyes meets the criteria of the fractality. For the fractal demention estimation the method of  “box-counting”can be applied.

  15. Stress relief of transition zones

    Woodward, J.; van Rooyen, D.


    This paper considers the problem of intergranular stress corrosion cracking, initiated on the primary side, in the expansion transition region of roller expanded Alloy 600 tubing. In general it is believed that residual stresses, arising from the expansion process, are the cause of the problem. The work reported here concentrated on the identification of an optimal, in-situ stress relief treatment.

  16. Digital relief generation from 3D models

    Wang, Meili; Sun, Yu; Zhang, Hongming; Qian, Kun; Chang, Jian; He, Dongjian


    It is difficult to extend image-based relief generation to high-relief generation, as the images contain insufficient height information. To generate reliefs from three-dimensional (3D) models, it is necessary to extract the height fields from the model, but this can only generate bas-reliefs. To overcome this problem, an efficient method is proposed to generate bas-reliefs and high-reliefs directly from 3D meshes. To produce relief features that are visually appropriate, the 3D meshes are first scaled. 3D unsharp masking is used to enhance the visual features in the 3D mesh, and average smoothing and Laplacian smoothing are implemented to achieve better smoothing results. A nonlinear variable scaling scheme is then employed to generate the final bas-reliefs and high-reliefs. Using the proposed method, relief models can be generated from arbitrary viewing positions with different gestures and combinations of multiple 3D models. The generated relief models can be printed by 3D printers. The proposed method provides a means of generating both high-reliefs and bas-reliefs in an efficient and effective way under the appropriate scaling factors.

  17. Running gratings in photoconductive materials

    Kukhtarev, N. V.; Kukhtareva, T.; Lyuksyutov, S. F.


    gratings at small-contrast approximation and also are applicable for the description of space-charge wave domains. We discuss spatial domain and subharmonic beam formation in bismuth silicon oxide (BSO) crystals in the framework of the small-contrast approximation of STPM. The experimental results...

  18. Calculation of thermal noise in grating reflectors

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


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

  19. The Team Approach to Pain Relief

    ... Issue Past Issues The Team Approach to Pain Relief Past Issues / Fall 2007 Table of Contents For ... with her quality of life, and acupuncture brought relief from severe shoulder pain. "I'm functional again. ...

  20. Curved VPH gratings for novel spectrographs

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


    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.

  1. Grating light modulator for projection display

    Jiyong Sun; Shanglian Huang; Jie Zhang; Zhihai Zhang; Yong Zhu


    A novel grating light modulator for projection display is introduced. It consists of an upper moveable grat-ing, a bottom mirror, and four supporting posts between them. The moveable grating and the bottom mir-ror compose a phase grating whose phase difference is controlled by the actuating voltage. When the phase difference is 2kπ, the grating light modulator will switch the incident light to zero-order diffraction; when the phase difference is (2k - 1)π, the grating light modulator will diffract light to first-order diffraction. A 16 × 16 modulator array is fabricated by the surface micromachining technology. The device works well when it is actuated by a voltage with 1-kHz frequency and 10-V amplitude. The fabricated grating light modulator can show blackness and brightness when controlled by the voltage. This modulator has potential applications in projection display system.

  2. 47 CFR 69.727 - Regulatory relief.


    ... similarly situated customers; and (ii) The price cap LEC excludes all contract tariff offerings from price... customer. (b) Phase II relief. Upon satisfaction of the Phase II triggers specified in §§ 69.709(c) or 69... Pricing Flexibility § 69.727 Regulatory relief. (a) Phase I relief. Upon satisfaction of the Phase I...

  3. 7 CFR 1465.33 - Equitable relief.


    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Equitable relief. 1465.33 Section 1465.33 Agriculture... § 1465.33 Equitable relief. (a) If a participant relied upon the advice or action of any authorized NRCS... participant may be eligible for equitable relief under 7 CFR part 635, section 635.3. The financial or...

  4. 28 CFR 36.504 - Relief.


    ... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Relief. 36.504 Section 36.504 Judicial... COMMERCIAL FACILITIES Enforcement § 36.504 Relief. (a) Authority of court. In a civil action under § 36.503, the court— (1) May grant any equitable relief that such court considers to be appropriate, including...

  5. 29 CFR 553.225 - Early relief.


    ... 29 Labor 3 2010-07-01 2010-07-01 false Early relief. 553.225 Section 553.225 Labor Regulations... relief. It is a common practice among employees engaged in fire protection activities to relieve employees on the previous shift prior to the scheduled starting time. Such early relief time may occur...

  6. 29 CFR 4041.4 - Disaster relief.


    ... 29 Labor 9 2010-07-01 2010-07-01 false Disaster relief. 4041.4 Section 4041.4 Labor Regulations...-EMPLOYER PLANS General Provisions § 4041.4 Disaster relief. When the President of the United States declares that, under the Disaster Relief Act (42 U.S.C. 5121, 5122(2), 5141(b)), a major disaster exists...

  7. 29 CFR 1614.505 - Interim relief.


    ... 29 Labor 4 2010-07-01 2010-07-01 false Interim relief. 1614.505 Section 1614.505 Labor Regulations... OPPORTUNITY Remedies and Enforcement § 1614.505 Interim relief. (a)(1) When the agency appeals and the case... interim relief. (2) Service under the temporary or conditional restoration provisions of paragraph (a)(1...

  8. 7 CFR 276.5 - Injunctive relief.


    ... 7 Agriculture 4 2010-01-01 2010-01-01 false Injunctive relief. 276.5 Section 276.5 Agriculture... Injunctive relief. (a) General. If FNS determines that a State agency has failed to comply with the Food... Secretary may seek injunctive relief against the State agency to require compliance. The Secretary may...

  9. 20 CFR 627.803 - Relief.


    ... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false Relief. 627.803 Section 627.803 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR GENERAL PROVISIONS GOVERNING PROGRAMS... Relief. In ordering relief, the ALJ shall have the full authority of the Secretary under section 164 of...

  10. 24 CFR 7.44 - Interim relief.


    ... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false Interim relief. 7.44 Section 7.44... § 7.44 Interim relief. (a) When the Department appeals and the case involves removal, separation, or... outcome of the Department appeal. The employee may decline the offer of interim relief. (b) Service under...

  11. 7 CFR 1466.33 - Equitable relief.


    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Equitable relief. 1466.33 Section 1466.33 Agriculture... Administration § 1466.33 Equitable relief. (a) If a participant relied upon the advice or action of any... relief, to the extent it is deemed desirable by NRCS, to provide a fair and equitable treatment because...

  12. 7 CFR 1470.34 - Equitable relief.


    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Equitable relief. 1470.34 Section 1470.34 Agriculture... § 1470.34 Equitable relief. (a) If a participant relied upon the advice or action of NRCS and did not... be eligible for equitable relief under 7 CFR part 635. The financial or technical liability for any...

  13. 12 CFR 268.505 - Interim relief.


    ... 12 Banks and Banking 3 2010-01-01 2010-01-01 false Interim relief. 268.505 Section 268.505 Banks... REGARDING EQUAL OPPORTUNITY Remedies and Enforcement § 268.505 Interim relief. (a)(1) When the Board appeals... offer of interim relief. (2) Service under the temporary or conditional restoration provisions of...

  14. 7 CFR 636.20 - Equitable relief.


    ... 7 Agriculture 6 2010-01-01 2010-01-01 false Equitable relief. 636.20 Section 636.20 Agriculture... AGRICULTURE LONG TERM CONTRACTING WILDLIFE HABITAT INCENTIVES PROGRAM § 636.20 Equitable relief. (a) If a... as meeting program requirements and grant relief because of the good-faith reliance on the part of...

  15. 7 CFR 795.24 - Relief.


    ... 7 Agriculture 7 2010-01-01 2010-01-01 false Relief. 795.24 Section 795.24 Agriculture Regulations... PROVISIONS COMMON TO MORE THAN ONE PROGRAM PAYMENT LIMITATION General § 795.24 Relief. If a producer relied... reviewing authority makes a more restrictive determination, the Deputy Administrator may grant relief only...

  16. 32 CFR 516.19 - Injunctive relief.


    ... 32 National Defense 3 2010-07-01 2010-07-01 true Injunctive relief. 516.19 Section 516.19 National... RELATIONS LITIGATION Reporting Legal Proceedings to HQDA § 516.19 Injunctive relief. (a) General. Plaintiffs... injunctive relief: (1) Plaintiff's likelihood of success on the merits. (2) Whether plaintiff will be...

  17. 18 CFR 281.215 - Additional relief.


    ... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Additional relief. 281... Additional relief. If an interstate pipeline rejects (under § 281.210 or otherwise) a request for... aggrieved by such action may file a request for relief from curtailment under § 385.206 of this chapter. The...

  18. 49 CFR 1108.4 - Relief.


    ... 49 Transportation 8 2010-10-01 2010-10-01 false Relief. 1108.4 Section 1108.4 Transportation Other... TRANSPORTATION BOARD § 1108.4 Relief. (a) Subject to specification in the complaint, as provided in § 1108.7 herein, an Arbitrator may grant the following types of relief: (1) Monetary damages, to the extent...

  19. Service Learning Through Disaster Relief

    Donna J. Duerst


    Full Text Available The Rock County 4-H Disaster Relief Committee raised $1,550 to aid tsunami victims in Sri Lanka and then turned its attention to Hurricane Katrina relief efforts. Thirty-one 4-H youth participated in a service learning trip to the South with the objectives of helping hurricane victims, learning about new cultures and achieving personal growth during three days of service projects in Louisiana and Mississippi. Their written reflections and other evaluative measures revealed they learned about southern culture, gained a greater appreciation for their lives, gained self confidence and developed a desire to help others more often. The trip was a valuable developmental experience for the youth, and information from the trip could be utilized to create similar experiences based on service learning. This article provides an overview of the trip and describes the evaluation methods used to measure learning and assess personal growth.

  20. Cross-fiber Bragg grating transducer

    Albin, Sacharia (Inventor); Zheng, Jianli (Inventor); Lavarias, Arnel (Inventor)


    A transducer has been invented that uses specially-oriented gratings in waveguide a manner that allows the simultaneous measurement of physical phenomena (such as shear force, strain and temperature) in a single sensing element. The invention has a highly sensitive, linear response and also has directional sensitivity with regard to strain. The transducer has a waveguide with a longitudinal axis as well as two Bragg gratings. The transducer has a first Bragg grating associated with the waveguide that has an angular orientation .theta..sub.a relative to a perpendicular to the longitudinal axis such that<.theta..sub.a <.theta..sub.max. The second Bragg grating is associated with the waveguide in such a way that the angular orientation .theta..sub.b of the grating relative to a perpendicular to the longitudinal axis is (<.theta..sub.b < The first Bragg grating can have a periodicity .LAMBDA..sub.a and the second Bragg grating can have a periodicity .LAMBDA..sub.b such that the periodicity .LAMBDA..sub.a of the first Bragg grating does not equal the periodicity .LAMBDA..sub.b of the second Bragg grating. The angle of the gratings can be such that .theta..sub.a The waveguide can assume a variety of configurations, including an optical fiber, a rectangular waveguide and a planar waveguide. The waveguide can be fabricated of a variety of materials, including silica and polymer material.

  1. The spectral combination characteristic of grating and the bi-grating diffraction imaging effect

    ZHANG WeiPing; HE XiaoRong


    This paper reports on a new property of grating,namely spectral combination,and on bi-grating diffraction imaging that is based on spectral combination.The spectral combination characteristic of a grating is the capability of combining multiple light beams of different wavelengths incident from specific angles into a single beam.The bi-grating diffraction imaging is the formation of the image of an object with two gratings: the first grating disperses the multi-color light beams from the object and the second combines the dispersed light beams to form the image.We gave the conditions necessary for obtaining the spectral combination.We also presented the equations that relate the two gratings' spatial frequencies,diffraction orders and positions necessary for obtaining the bi-grating diffraction imaging.

  2. Nanoporous Polymeric Grating-Based Biosensors

    Gao, Tieyu


    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.

  3. Plasmonic Transmission Gratings – Fabrication and Characterization

    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...... beam (FIB) microscope, using gallium and a neutralizing electron beam. We investigate the SPP coupling strength with respect to varying top layers and under collimated, oblique-angled excitation, with respect to the effect of finite gratings as opposed to perfect periodicity. We characterize...

  4. Laguerre-Gauss beam generation in IR and UV by subwavelength surface-relief gratings

    Vertchenko, Larissa; Shkondin, Evgeniy; Malureanu, Radu


    layerdepositions and dry etch techniques. We exploit the phenomenon of formbirefringence to give rise to the spin-to-orbital angular momentum conversion.We demonstrate that these plates can generate beams with high quality for theUV and IR range, allowing them to interact with high power laser sources orinside......The angular momentum of light can be described by the states of spin angularmomentum, associated with polarization, and orbital angular momentum, relatedto the helical structure of the wave front. Laguerre-Gaussian beams carryorbital angular momentum and their generation can be done by using...... an opticaldevice known as q-plate. However, due to the usage of liquid crystals, thesecomponents may be restricted to operate in specific wavelengths and low powersources. Here we present the fabrication and characterization of q-plates madewithout liquid crystals, using processes of e-beam lithography, atomic...

  5. Laguerre-Gauss beam generation in IR and UV by subwavelength surface-relief gratings

    Vertchenko, Larissa; Malureanu, Radu; Monken, Carlos H


    The angular momentum of light can be described by the states of spin angular momentum, associated with polarization, and orbital angular momentum, related to the helical structure of the wave front. Laguerre-Gaussian beams carry orbital angular momentum and their generation can be done by using an optical device known as q-plate. However, due to the usage of liquid crystals, these components may be restricted to operate in specific wavelengths and low power sources. Here we present the fabrication and characterization of q-plates made without liquid crystals, using processes of e-beam lithography, atomic layer depositions and dry etch techniques. We exploit the phenomenon of form birefringence to give rise to the spin-to-orbital angular momentum conversion. We demonstrate that these plates can generate beams with high quality for the UV and IR range, allowing them to interact with high power laser sources or inside laser cavities.

  6. eROSITA on SRG

    Predehl, P.


    eROSITA is the primary telescope on the Russian-German X-ray mission Spectrum-Roentgen-Gamma. The instrument is near its completion: All parts are in place, all seven cameras and seven mirrors plus spares are calibrated, the integration is almost done. All subsystems behave as planned, the performance is as expected. Now we are in the process of doing the final tests before eROSITA will be shipped to Russia for integration into the spacecraft. The launch is now planned for end of September 2017. In parallel to the instrument development, the preparation of the mission is also on its way: The data analysis software is operating, and we are working together with our Russian partners on details of the mission planning. More than 100 German scientists organised in 12 working groups contribute to the mission with simulations, analyses and scientific proposals.

  7. Photo-induced refractive index and topographical surface gratings in functionalized nanocarbon solid film

    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: [Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)


    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. Coordinating Robot Teams for Disaster Relief


    Coordinating Robot Teams for Disaster Relief Mark Roberts1, Thomas Apker2, Benjamin Johnson1, Bryan Auslander3, Briana Wellman4 & David W...for Humanitarian Assistance / Disaster Relief operations. We demonstrate that the SDP responds to a dynamic, open world while ensuring that vehicles...facilitate such information gathering tasks, freeing humans to perform more critical tasks in Humanitarian Assistance / Disaster Relief (HA/DR

  9. Biosensing with optical fiber gratings

    Chiavaioli Francesco


    Full Text Available Optical fiber gratings (OFGs, especially long-period gratings (LPGs and etched or tilted fiber Bragg gratings (FBGs, are playing an increasing role in the chemical and biochemical sensing based on the measurement of a surface refractive index (RI change through a label-free configuration. In these devices, the electric field evanescent wave at the fiber/surrounding medium interface changes its optical properties (i.e. intensity and wavelength as a result of the RI variation due to the interaction between a biological recognition layer deposited over the fiber and the analyte under investigation. The use of OFG-based technology platforms takes the advantages of optical fiber peculiarities, which are hardly offered by the other sensing systems, such as compactness, lightness, high compatibility with optoelectronic devices (both sources and detectors, and multiplexing and remote measurement capability as the signal is spectrally modulated. During the last decade, the growing request in practical applications pushed the technology behind the OFG-based sensors over its limits by means of the deposition of thin film overlays, nanocoatings, and nanostructures, in general. Here, we review efforts toward utilizing these nanomaterials as coatings for high-performance and low-detection limit devices. Moreover, we review the recent development in OFG-based biosensing and identify some of the key challenges for practical applications. While high-performance metrics are starting to be achieved experimentally, there are still open questions pertaining to an effective and reliable detection of small molecules, possibly up to single molecule, sensing in vivo and multi-target detection using OFG-based technology platforms.

  10. A sigh of relief or a sigh of expected relief: Sigh rate in response to dyspnea relief.

    Vlemincx, Elke; Meulders, Michel; Luminet, Olivier


    Research has suggested that sighs may serve a regulatory function during stress and emotions by facilitating relief. Evidence supports the hypotheses that sighs both express and induce relief from stress. To explore the potential role of sighs in the regulation of symptoms, the present study aimed to investigate the relationship between sighs and relief of symptoms, and relief of dyspnea, specifically. Healthy volunteers participated in two studies (N = 44, N = 47) in which dyspnea was induced by mild (10 cmH2 O/l/s) or high (20 cmH2 0/l/s) inspiratory resistances. Dyspnea relief was induced by the offset of the inspiratory resistances (transitions from high and mild inspiratory resistance to no resistance). Control comparisons included dyspnea increases (transitions from no or mild inspiratory resistance to high inspiratory resistance) and dyspnea continuations (continuations of either no resistance or a high resistance). In Experiment 1, dyspnea levels were cued. In Experiment 2, no cues were provided. Sigh rate during dyspnea relief was significantly higher compared to control conditions, and sigh rate increased as self-reported dyspnea decreased. Additionally, sigh rate was higher during cued dyspnea relief compared to noncued dyspnea relief. These results suggest that sighs are important markers of dyspnea relief. Moreover, sighs may importantly express dyspnea relief, as they are related to experiential dyspnea decreases and occur more frequently during expected dyspnea relief. These findings suggest that sighs may not only be important in the regulation of stress and emotions, but also may be functional in the regulation of dyspnea. © 2017 Society for Psychophysiological Research.

  11. Fiber Bragg Grating Based Thermometry

    Ahmed, Zeeshan; 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 a hermetically sealed dry Argon environment, that 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 the peak center fitting and by thermal aging of polyimide coated fibers.

  12. Birefringence properties of a polarization maintaining Panda fibre during Bragg grating regeneration

    Polz, Leonhard; Jarsen, Andreas; Bartelt, Hartmut; Roths, Johannes


    Regeneration of fibre Bragg gratings under application of a high temperature annealing process in a high birefringent polarisation maintaining fibre of type Panda was investigated. During the annealing process, a distinct nonlinearity and hysteresis of the birefringence with temperature was observed. After the temperature process, the birefringence between slow and fast axis at room temperature was nearly doubled, which is in agreement with observations of other researchers. The hysteresis in birefringence might be explained by the crossing of the transition temperature of the stress applying parts and the relief of in-frozen mechanical and thermal stresses.

  13. The spectral combination characteristic of grating and the bi-grating diffraction imaging effect


    This paper reports on a new property of grating, namely spectral combination, and on bi-grating diffraction imaging that is based on spectral combination. The spectral combination characteristic of a grating is the capability of combining multiple light beams of different wavelengths incident from specific angles into a single beam. The bi-grating diffraction imaging is the formation of the image of an object with two gratings: the first grating disperses the multi-color light beams from the object and the second combines the dispersed light beams to form the image. We gave the conditions necessary for obtaining the spectral combination. We also presented the equations that relate the two gratings’ spatial frequencies, diffraction orders and positions necessary for obtaining the bi-grating diffraction imaging.

  14. Diffractive Optics of Anisotropic Polarization Gratings

    Xu, M.


    Diffraction gratings are being used to manipulate light in many different applications, such as in flat panel display systems, modern lighting systems, and optical recording. Diffraction gratings can be made polarization selective due to form birefringence. An alternative approach to polarization

  15. Antireflective characteristics of hemispherical grid grating

    REN Zhibin; JIANG Huilin; LIU Guojun; SUN Qiang


    In this paper, the optical characteristics of new type hemispherical grid subwavelength grating are studied by using multi-level column structure approximation and rigorous coupled-wave analysis. This kind of grating could be fabricated by chemical methods, thus simplifying the fabrication technology of subwavelength gratings for visible light. By computer simulation and calculation, the hemispherical grid subwavelength gratings are proved to have antireflective characteristics. Two design schemes of this kind of grating are presented. In the first scheme, the grating could achieve a reflectivity as low as 3.4416×10-7, which can be adapted to 0.46―0.7 μm of visible waveband and ±12° incident angle field. In the second scheme, the grating can achieve a reflectivity as low as 3.112×10-4 and adapted to the whole visible waveband and ±23° incident angle field. The application field of the latter scheme is wider than that of the former. The results of this paper could provide reference for the applications of the hemispherical grid subwavelength gratings for the visible waveband.

  16. Straw combustion on slow-moving grates

    Kær, Søren Knudsen


    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...

  17. The Flexibility of Pusher Furnace Grate

    Słowik J.A.


    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%.

  18. Oxycodone combinations for pain relief.

    Raffa, R B; Pergolizzi, J V; Segarnick, D J; Tallarida, R J


    No single analgesic drug provides the perfect therapeutic/adverse effect profile for every pain condition. In addition to convenience and possibly improved compliance, a combination of analgesic drugs offers the potential, requiring verification, of providing greater pain relief and/or reduced adverse effects than the constituent drugs when used individually. We review here analgesic combinations containing oxycodone. We found surprisingly little preclinical information about the analgesic or adverse effect profiles of the combinations (with acetaminophen, paracetamol, nonsteroidal anti-inflammatory drugs, morphine, gabapentin or pregabalin). Clinical experience and studies suggest that the combinations are safe and effective and may offer certain advantages. As with all combinations, the profile of adverse effects must also be determined in order to provide the clinician with the overall benefit/risk assessment.

  19. Exercise Based- Pain Relief Program

    Zadeh, Mahdi Hossein

    in the current study was to use exercise induced- muscle damage followed by ECC as an acute pain model and observe its effects on the sensitivity of the nociceptive system and blood supply in healthy subjects. Then, the effect of a repeated bout of the same exercise as a healthy pain relief strategy......Exercise-based pain management programs are suggested for relieving from musculoskeletal pain; however the pain experienced after unaccustomed, especially eccentric exercise (ECC) alters people´s ability to participate in therapeutic exercises. Subsequent muscle pain after ECC has been shown...... to cause localized pressure pain and hyperalgesia. A prior bout of ECC has been repeatedly reported to produce a protective adaptation known as repeated bout effect (RBE). One of the main scopes of the current project was to investigate the adaptations by which the RBE can be resulted from. The approach...

  20. Pain relief can be painful

    Ashish Bindra


    Full Text Available Mandibular nerve block is periodically used procedure used to treat neuralgic pain in the distribution of trigeminal nerve. It is a commonly performed block in outpatient settings at our institute. We present a case of an elderly edentulous patient with trigeminal neuralgia who suffered recurrent temporomandibular joint (TMJ dislocation following mandibular nerve block. The patient presented with complaints of severe pain, inability to close mouth, and eat food since 2 days. Anterior closed reduction of TMJ resulted in reduction of joint and immediate pain relief. However, the maneuver failed due to recurrent dislocation of the joint. A Barton dressing was applied to prevent another dislocation. This was followed by autologous blood injection into the joint. This case focuses on the preponderance of clinical evaluation and accentuates the need for additional forethought to be taken during pain procedures, particularly in the geriatric population.

  1. Reflectivity-modulated grating-mirror


    The invention relates to vertical cavity lasers (VCL) incorporating a reflectivity-modulated grating mirror (1) for modulating the laser output. A cavity is formed by a bottom mirror (4), an active region (3), and an outcoupling top grating mirror (1) formed by a periodic refractive index grating...... to the oscillation axis. A modulated voltage (91) is applied in reverse bias between the n- and p-doped layers to modulate the refractive index of the electrooptic material layer (12) and thereby the reflectivity spectrum of the grating mirror (1). The reflectivity of the grating mirror (1) can be modulated between...... 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...

  2. Alignment free characterization of 2D gratings

    Madsen, Morten Hannibal; Hansen, Poul-Erik; Jørgensen, Jan Friis


    Fast characterization of 2-dimensional gratings is demonstrated using a Fourier lens optical system and a differential optimization algorithm. It is shown that both the grating specific parameters such as the basis vectors and the angle between them and the alignment of the sample, such as the rotation of the sample around the x-, y-, and z-axis, can be deduced from a single measurement. More specifically, the lattice vectors and the angle between them have been measured, while the corrections of the alignment parameters are used to improve the quality of the measurement, and hence reduce the measurement uncertainty. Alignment free characterization is demonstrated on both a 2D hexagonal grating with a period of 700 nm and a checkerboard grating with a pitch of 3000 nm. The method can also be used for both automatic alignment and in-line characterization of gratings.

  3. Grating droplets with a mesh

    Soto, Dan; Le Helloco, Antoine; Clanet, Cristophe; Quere, David; Varanasi, Kripa


    A drop thrown against a mesh can pass through its holes if impacting with enough inertia. As a result, although part of the droplet may remain on one side of the sieve, the rest will end up grated through the other side. This inexpensive method to break up millimetric droplets into micrometric ones may be of particular interest in a wide variety of applications: enhancing evaporation of droplets launched from the top of an evaporative cooling tower or preventing drift of pesticides sprayed above crops by increasing their initial size and atomizing them at the very last moment with a mesh. In order to understand how much liquid will be grated we propose in this presentation to start first by studying a simpler situation: a drop impacting a plate pierced with a single off centered hole. The study of the role of natural parameters such as the radius drop and speed or the hole position, size and thickness allows us to discuss then the more general situation of a plate pierced with multiple holes: the mesh.

  4. Efficient beam splitting with continuous relief DOEs and microlens arrays

    Krasnaberski, Aliaksei; Miklyaev, Yuri; Pikhulya, Denis; Kleinschmidt, Lisa; Imgrunt, Waleri; Ivanenko, Mikhail; Lissotschenko, Vitalij


    Diffractive optical elements (DOEs) are of rising importance for many industrial laser applications, especially for laser beam shaping and laser beam splitting. Typically, such applications require high damage threshold of the diffractive optical elements as well as high diffraction efficiency. Usually DOEs with multilevel (step-like) phase profiles are made microlithographically and suffer from "quantisation" errors and scattering on profile derivative discontinuities. The steplike structure lowers the DOE damage threshold compared to the intrinsic material values. LIMO's microoptical technology is suitable for the production of high-precision free programmable continuous surface profiles in optical glasses, crystals and metals. It can be applied for manufacturing of microlens and micro-mirror arrays as well as for manufacturing of diffractive optics with continuous reliefs. Both the arrays and DOEs with continuous relief are suitable for high efficiency laser beam splitting. However, the design approaches to obtain a desirable solution for the corresponding continuous phase profiles are different. The results of the wave-optical simulations made by LIMO's own program and by VirtualLab software, and experimental studies for a 1 to 11 beam splitter with a continuous profile for the wavelength of 532 nm are presented. Continuous phase profiles for the DOEs were designed by a procedure based on the theory of beam splitting by a phase grating. Comparative theoretical and experimental studies were also done for splitting with a double-sided microlens array. For both types of beam splitting the efficiency can be very high (> 98%). The DOEs show especially high homogeneities of the resulting intensity distribution, however, they are much more sensitive to wavelength variations. The microlens arrays demonstrate even weaker ghost orders as the DOE splitters and their surface profiles are simpler. However, the efficiency and homogeneity suffer on interlens gaps.

  5. Inexpensive tamper proof safety relief valve

    Frankewich, P. A.


    Basic relief valve has added safety relief valve capability that relieves overpressure before failure can occur. It may be installed in inaccesible areas with a high degree of reliability, constructed from a variety of materials, and adapted to the user's specific application.

  6. 44 CFR 68.12 - Relief.


    ... 44 Emergency Management and Assistance 1 2010-10-01 2010-10-01 false Relief. 68.12 Section 68.12 Emergency Management and Assistance FEDERAL EMERGENCY MANAGEMENT AGENCY, DEPARTMENT OF HOMELAND SECURITY... Relief. The final determination may be appealed by the appellant(s) to the United States district court...

  7. 24 CFR 220.753 - Forbearance relief.


    ... 24 Housing and Urban Development 2 2010-04-01 2010-04-01 false Forbearance relief. 220.753 Section 220.753 Housing and Urban Development Regulations Relating to Housing and Urban Development (Continued... and Obligations-Projects Project Mortgage Insurance § 220.753 Forbearance relief. (a) In a case where...

  8. 47 CFR 1.6009 - Relief.


    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Relief. 1.6009 Section 1.6009 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL PRACTICE AND PROCEDURE Implementation of Section 325(e) of the... Carriers for Retransmission Without Consent § 1.6009 Relief. If the Commission determines that a satellite...

  9. 24 CFR 236.255 - Forbearance relief.


    ... 24 Housing and Urban Development 2 2010-04-01 2010-04-01 false Forbearance relief. 236.255 Section 236.255 Housing and Urban Development Regulations Relating to Housing and Urban Development (Continued... Insurance § 236.255 Forbearance relief. (a) In a case where the mortgage is in default, the mortgagor and...

  10. 24 CFR 221.761 - Forbearance relief.


    ... 24 Housing and Urban Development 2 2010-04-01 2010-04-01 false Forbearance relief. 221.761 Section 221.761 Housing and Urban Development Regulations Relating to Housing and Urban Development (Continued... § 221.761 Forbearance relief. (a) In a case where the mortgage is in default, the mortgagor and the...

  11. 基于RMxprt Maxwel l的SRG低速电流斩波控制研究%Study of Low Velocity Current Chopping Control for SRG Based on RMxprt Maxwell

    刘烈焜; 易灵芝; 徐斌; 罗百敏; 朱广辉; 吴炜楠


    基于 Ansoft/RMxprt 和 Maxwell的仿真环境,建立开关磁阻发电机仿真模型,采用有限元分析,研究其静态和动态特性;研究旋转电机优化设计方法,指导开关磁阻发电机及其控制系统优化设计。采用低速段电流斩波控制,得到最佳开通角、关断角、转速、和电流滞环控制宽度等参数,指导样机发电实验,增加发电输出功率,提高 SRG发电系统稳定性。%The module of 8/6 phase switched reluctance generator was built under Ansoft/RMxprt and Maxwell.The basic static performance and dynamic performance of SRG were analyzed based on the model by finite element analysis;The results of optimization design of rotating electrical machines can be available used to design and optimize the new type ma-chine and its control system.In low velocity,a new type current chopping controller is adopted,the control parameters can be got,such asθon ,θoff ,velocity and current chop control width,so the prototype machine can be achieved,and the output power can be enlarge,and the stability of SRG power system can be increased.

  12. Thermomechanical analysis of a composite grating

    Cid, Jose [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas; Araujo, Marcia [PETROBRAS, Rio de Janeiro, RJ (Brazil); DeJoode, Alex; Abd, Imad [Reverse Engineering Ltd, Didsbury, Manchester (United Kingdom)


    The aim of the work carried out was to assess the structural performance of polymer composite gratings during a fire. The gratings are made from Fibre Reinforced Plastic (GRP) and are proposed for use as walkways on offshore platforms. During a fire, the gratings are subjected to high temperatures which reduce their structural performance. A numerical model based on experimental results, as well as data published in the literature was developed. The investigation focused on assessing the grating load capacity to carry a fire-fighter and fire-fighting equipment during a fire situation. It was assumed that 120 deg C would be the highest practical temperature for a fire-fighter to attack a fire. Subsequently, the grating performance was investigated for a range of temperatures from ambient to 120 deg C with the temperatures 60, 90 and 120 deg C representing the key targets for lower middle and upper limits. The requirements to assess the mechanical performance of the grating at the local level and global levels necessitated the need to develop a numerical technique to enhance the conventional functionality of the finite element code. The developed material model and the associated numerical technique produced a sophisticated numerical tool capable of assessing the structural response of the gratings at elevated temperatures up to 120 deg C. The comparison between the numerical results and the measured data illustrates robustness of the developed numerical tools, although certain predictions showed relatively poorer agreement than anticipated. (author)

  13. Planar double-grating microspectrometer.

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


    We report on a miniature spectrometer with a volume of 0.135 cm(3) and dimensions of 3x3x11 mm, mounted directly on the surface of a CCD sensor. The spectrometer is formed by two flat diffraction gratings that are designed to perform both the dispersion and imaging functions, eliminating the need for any spherical optics. Two separate parts of the device were fabricated with the single-mask 1 mum lithography on a single glass wafer. The wafer was diced and the device was assembled and directly mounted onto a CCD sensor. The resolution of 3 nm, spectral range of 450 to 750 nm and the optical throughput of ~9% were measured to be in a complete agreement with the model used for the development of the device.

  14. 21 CFR 133.147 - Grated American cheese food.


    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Grated American cheese food. 133.147 Section 133... Cheese and Related Products § 133.147 Grated American cheese food. (a)(1) Grated American cheese food is... granular mixture. (2) Grated American cheese food contains not less than 23 percent of milkfat,...

  15. Large size metallic glass gratings by embossing

    Ma, J.; Yi, J.; Zhao, D. Q.; Pan, M. X.; Wang, W. H.


    Bulk metallic glasses have excellent thermoforming ability in their wide supercooled liquid region. We show that large-size metallic glass grating (˜8 × 8 mm2) with fine periodicity and ultra smooth surface feature can be readily fabricated by hot embossing. The method for fabrication of gratings is proved to be much cheaper, and requires low pressure and short time (less than 30 s). The metallic glass gratings exhibit comparable optical properties such as rainbow-like spectrum when shone by fluorescent lamp light.

  16. Fiber Bragg Grating Sensors for Harsh Environments

    Stephen J. Mihailov


    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.

  17. Advanced experimental applications for x-ray transmission gratings Spectroscopy using a novel grating fabrication method

    Hurvitz, G; Strum, G; Shpilman, Z; Levy, I; Fraenkel, M


    A novel fabrication method for soft x-ray transmission grating and other optical elements is presented. The method uses Focused-Ion-Beam (FIB) technology to fabricate high-quality free standing grating bars on Transmission Electron Microscopy grids (TEM-grid). High quality transmission gratings are obtained with superb accuracy and versatility. Using these gratings and back-illuminated CCD camera, absolutely calibrated x-ray spectra can be acquired for soft x-ray source diagnostics in the 100-3000 eV spectral range. Double grating combinations of identical or different parameters are easily fabricated, allowing advanced one-shot application of transmission grating spectroscopy. These applications include spectroscopy with different spectral resolutions, bandwidths, dynamic ranges, and may serve for identification of high-order contribution, and spectral calibrations of various x-ray optical elements.

  18. Influence of grating thickness in low-contrast subwavelength grating concentrating lenses

    Ye, Mao; Yi, Ya Sha


    Conventional subwavelength grating concentrating lenses are designed based on calculated phase overlap, wherein the phase change is fixed by the grating thickness, bar-width, and airgap, and therefore the focus. We found that certain concentration effects can still be maintained by changing the grating thickness with the same bar-widths and airgap dimensions. Following that, we discovered the existence of the grating thickness threshold; light concentration intensity spikes upon exceeding this limit. However, the light concentration property does not change continuously with respect to a steady increase in grating thickness. This observation indicates that there exists a concentration mode self-interference effect along the light propagation direction inside the gratings. Our results may provide guidance in designing and fabricating microlenses in a potentially more easy and controllable manner. Such approaches can be utilized in various integrated nanophotonics applications ranging from optical cavities and read/write heads to concentrating photovoltaics.

  19. Long period fiber gratings induced by mechanical resonance

    Shahal, Shir; Duadi, Hamootal; Fridman, Moti


    We present a simple, and robust method for writing long period fiber gratings with low polarization dependent losses. Our method is based on utilizing mechanical vibrations of the tapered fiber while pooling it. Our method enables real-time tunability of the periodicity, efficiency and length of the grating. We also demonstrate complex grating by writing multiple gratings simultaneously. Finally, we utilized the formation of the gratings in different fiber diameters to investigate the Young's modulus of the fiber.

  20. Access Platforms for Offshore Wind Turbines Using Gratings

    Andersen, Thomas Lykke; Rasmussen, Michael R.


    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........ The derived reduction factors are expected to be applicable to design of offshore wind turbine access platforms with gratings where slamming also is an important factor....

  1. Liquid crystal on subwavelength metal gratings

    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)


    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.

  2. Theory of photorefractive dynamic grating formulation


    The photorefractive holographic recording and two-beam coupling are both dynamic grating formulation process. The interference light intensity of the two coherent beams induces a phase grating though photo-induced refractive index variation and the phase grating changing the intensities of the two beams through beam-coupling take place at the same time. By solving simultaneously the band transport equations and wave-coupled equations, and using the light intensity modulation as the main variable, the analytic solution is obtained, which is valid for any light intensity modulation and constant light excitation efficiency. Here all the mechanics of drift, diffusion and photovoltaic effect are considered. The result shows that the modulation of the dynamic grating varies more slowly compared with that of the linear modulation approximation.

  3. Hydraulic Capacity of an ADA Compliant Street Drain Grate

    Lottes, Steven A. [Argonne National Lab. (ANL), Argonne, IL (United States); Bojanowski, Cezary [Argonne National Lab. (ANL), Argonne, IL (United States)


    Resurfacing of urban roads with concurrent repairs and replacement of sections of curb and sidewalk may require pedestrian ramps that are compliant with the American Disabilities Act (ADA), and when street drains are in close proximity to the walkway, ADA compliant street grates may also be required. The Minnesota Department of Transportation ADA Operations Unit identified a foundry with an available grate that meets ADA requirements. Argonne National Laboratory’s Transportation Research and Analysis Computing Center used full scale three dimensional computational fluid dynamics to determine the performance of the ADA compliant grate and compared it to that of a standard vane grate. Analysis of a parametric set of cases was carried out, including variation in longitudinal, gutter, and cross street slopes and the water spread from the curb. The performance of the grates was characterized by the fraction of the total volume flow approaching the grate from the upstream that was captured by the grate and diverted into the catch basin. The fraction of the total flow entering over the grate from the side and the fraction of flow directly over a grate diverted into the catch basin were also quantities of interest that aid in understanding the differences in performance of the grates. The ADA compliant grate performance lagged that of the vane grate, increasingly so as upstream Reynolds number increased. The major factor leading to the performance difference between the two grates was the fraction of flow directly over the grates that is captured by the grates.

  4. Spatial heterodyne interferometry with polarization gratings.

    Kudenov, Michael W; Miskiewicz, Matthew N; Escuti, Michael J; Dereniak, Eustace L


    The implementation of a polarization-based spatial heterodyne interferometer (SHI) is described. While a conventional SHI uses a Michelson interferometer and diffraction gratings, our SHI exploits mechanically robust Wollaston prisms and polarization gratings. A theoretical model for the polarization SHI is provided and validated with data from our proof of concept experiments. This device is expected to provide a compact monolithic sensor for subangstrom resolution spectroscopy in remote sensing, biomedical imaging, and machine vision applications.

  5. Sampled phase-shift fiber Bragg gratings

    Xu Wang(王旭); Chongxiu Yu(余重秀); Zhihui Yu(于志辉); Qiang Wu(吴强)


    A phase-shift fiber Bragg grating (FBG) with sampling is proposed to generate a multi-channel bandpass filter in the background of multi-channel stopbands. The sampled noire fiber gratings are analyzed by Fourier transform theory first, and then simulation and experiment are performed, the results show that transmission peaks are opened in every reflective channel, the spectrum shape of every channel is identical.It can be used to fabricate multi-wavelength distributed feedback (DFB) fiber laser.

  6. Shaded Relief of Minnesota Elevation - Color

    Minnesota Department of Natural Resources — This file is a product of a shaded relief process on the 30 meter resolution Digital Elevation Model data (dem30im3). This image was created using a custom AML...

  7. Lake Bathymetric DEM Shaded Relief Image

    Minnesota Department of Natural Resources — Geo-referenced, shaded relief image of lake bathymetry classified at 5-foot depth intervals. This dataset has a cell resolution of 5 meters (occasionally 10m) as...

  8. Non-Drug Pain Relief: Imagery

    PATIENT EDUCATION Non-Drug Pain Relief: Imagery Relaxation helps lessen tension. One way to help decrease pain is to use imagery. Imagery is using your imagination to create a ...

  9. U.S. Coastal Relief Model

    National Oceanic and Atmospheric Administration, Department of Commerce — NGDC's U.S. Coastal Relief Model (CRM) provides the first comprehensive view of the U.S. coastal zone integrating offshore bathymetry with land topography into a...

  10. Enveloping Relief Surfaces of Landslide Terrain


    Two relief surfaces that envelop the rock fall region in a part of Garhwal Himalayas around Chamoli have been identified. Relative relief and absolute relief have been analyzed and the enveloping surfaces recorded at two levels of relief in the landscape. All landslide activity lies within these surfaces. The lower enveloping surface (800 m) dips due south by 7-8 degrees, due to an elevation rise of 100 meters within 12 km from south to north, i.e., a gradient of 8 percent. The nature of the surface is smooth. The upper enveloping surface (> 2500 m) is almost parallel to the lower one but its surface is undulatory due to landslides and denudation. The area has been a seismically active region and has undergone seismic activity up until recently, as evidenced by the Chamoli earthquake of 29th March 1999. The effects of earthquakes are seen at higher levels in the form of landslide imprints on the terrain.

  11. U.S. Coastal Relief Model - Hawaii

    National Oceanic and Atmospheric Administration, Department of Commerce — NGDC's U.S. Coastal Relief Model (CRM) provides the first comprehensive view of the U.S. coastal zone integrating offshore bathymetry with land topography into a...

  12. Shaded Relief of Minnesota Elevation - Black & White

    Minnesota Department of Natural Resources — This file is a product of a shaded relief process on the 30 meter resolution Digital Elevation Model data (dem30im3). This image was created using a custom AML...

  13. Brain Circuits Encoding Reward from Pain Relief

    Navratilova, Edita; Atcherley, Christopher; Porreca, Frank


    Relief from pain in humans is rewarding and pleasurable. Primary rewards, or reward predictive cues, are encoded in brain reward/motivational circuits. While considerable advances have been made in our understanding of reward circuits underlying positive reinforcement, less is known about the circuits underlying the hedonic and reinforcing actions of pain relief. We review findings from electrophysiological, neuroimaging and behavioral studies supporting the concept that the rewarding effect of pain relief requires opioid signaling in the anterior cingulate cortex, activation of midbrain dopamine neurons and release of dopamine in the nucleus accumbens. Understanding of circuits that govern the reward of pain relief may allow the discovery of more effective and satisfying therapies for patients with acute and chronic pain. PMID:26603560

  14. Optimization of a T-shaped optical grating for specific applications

    Szarvas, Tamás; Kis, Zsolt


    A detailed analysis of the optical reflectivity of a monolithic, T-shaped surface relief grating structure is carried out. It is shown that by changing the groove depths and widths, the frequency-dependent reflectivity of the diffraction grating can be greatly modified to obtain various specific optical elements. The basic T-shaped grating structure is optimized for three specific applications: a perfect mirror with a wide maximal reflection plateau, a bandpass filter, and a dichroic beam splitter. These specific mirrors could be used to steer the propagation of bichromatic laser fields, in situations where multilayer dielectric mirrors cannot be applied due to their worse thermomechanical properties. Colored maps are presented to show the reflection dependency on the variation of several critical structure parameters. To check the accuracy of the numerical results, four independent methods are used: finite-difference time-domain, finite-difference frequency-domain, method of lines, and rigorous coupled-wave analysis. The results of the independent numerical methods agree very well with each other indicating their correctness.

  15. Safety/relief-valve test program

    Hunter, J.A.


    In response to the NRC's Task 2.1.2 following the TMI-2 accident, government and industry programs were formulated to address the performance of safety and relief valve systems for pressurized and boiling water reactors. Objective is to demonstrate by testing and analysis that safety and relief valve systems in the reactor coolant system are qualified for the anticipated full range of reactor operating and accident conditions. The EPRI PWR program tested PWR safety valves and power operated relief valves (PORVs) under steam, liquid, and steam/liquid transition conditions. The program also tested PWR PORV block valves under steam conditions. The GE BWR program tested BWR relief and safety/relief valves under high pressure steam and low pressure liquid conditions. EG and G Idaho recent activities have focused on the evaluation of the industry test data, evaluation and modification of analytical codes for safety/relief valve system analysis, and initial evaluation of utility responses to US NRC program requirements.

  16. Analytical and numerical study on grating depth effects in grating coupled waveguide sensors

    Horvath, R.; Wilcox, L.C.; Pedersen, H.C.;


    The in-coupling process for grating-coupled planar optical waveguide sensors is investigated in the case of TE waves. A simple analytical model based on the Rayleigh-Fourier-Kiselev method is applied to take into account the depth of the grating coupler, which is usually neglected in the modeling...

  17. Interdigitated Electrodes and Anisotropic Diffraction Analysis of Phase And/or Lossy Gratings for Bulk and Integrated Applications.

    Glytsis, Elias Nikolaos


    Integrated optics is the primary area of application of the results of this thesis. Research and development of integrated optical circuits have been proceeding rapidly in recent years toward practical devices such acoustooptic spectrum analyzers, analog-to-digital converters, ultrafast logic gates, correlators, and multichannel data processors. These projects, however, have underscored the lack of fundamental knowledge regarding waveguide devices in anisotropic materials such as lithium niobate. Research into the basic physical modeling of these devices is the scope of this thesis. The main topics of this thesis are issues concerning the design and function of periodic interdigitated-electrode devices. At first, the electric field problem was solved taking into account the anisotropic properties of the substrate, the finite thickness of the electrodes, and the buffer layer between the electrodes and the substrate. The inclusion of the buffer layer is important for electrooptic applications since it is needed for the isolation of the optical field from the electrode metal. The bulk diffraction of plane waves by phase/amplitude anisotropic single or cascaded gratings with uniaxial anisotropic external regions has been analyzed. The various Bragg conditions have been classified and quantified. The diffraction of guided-waves by interdigitated-electrode induced phase gratings in uniaxial anisotropic waveguides has been treated. The electrostatic and grating diffraction analysis has been validated using available experimental data. The analysis is applicable to uniaxial anisotropic waveguides with the optic axis lying either in or perpendicular to the electrode surface. It applies to single-mode waveguides and to waveguides with negligible intermodal coupling. Finally, a new technique of designing antireflection coatings and gratings on lossy substrates has been developed in this thesis. The method employs high spatial-frequency surface-relief rectangular

  18. Sensing delamination in epoxy encapsulant systems with fiber Bragg gratings

    Jones, Brad H.; Rohr, Garth D.; Kaczmarowski, Amy K.


    Fiber Bragg gratings (FBGs) are well-suited for embedded sensing of interfacial phenomena in materials systems, due to the sensitivity of their spectral response to locally non-uniform strain fields. Over the last 15 years, FBGs have been successfully employed to sense delamination at interfaces, with a clear emphasis on planar events induced by transverse cracks in fiber-reinforced plastic laminates. We have built upon this work by utilizing FBGs to detect circular delamination events at the interface between epoxy films and alumina substrates. Two different delamination processes are examined, based on stress relief induced by indentation of the epoxy film or by cooling to low temperature. We have characterized the spectral response pre- and post-delamination for both simple and chirped FBGs as a function of delamination size. We show that delamination is readily detected by the evolution of a non-uniform strain distribution along the fiber axis that persists after the stressing condition is removed. These residual strain distributions differ substantially between the delamination processes, with indentation and cooling producing predominantly tensile and compressive strain, respectively, that are well-captured by Gaussian profiles. More importantly, we observe a strong correlation between spectrally-derived measurements, such as spectral widths, and delamination size. Our results further highlight the unique capabilities of FBGs as diagnostic tools for sensing delamination in materials systems.

  19. A novel single-order diffraction grating: Random position rectangle grating

    Zuhua, Yang; Qiangqiang, Zhang; Jing, Wang; Quanping, Fan; Yuwei, Liu; Lai, Wei; Leifeng, Cao


    Spectral diagnosis of radiation from laser plasma interaction and monochromation of radiation source are hot and important topics recently. Grating is one of the primary optical elements to do this job. Although easy to fabricate, traditional diffraction grating suffers from multi-order diffraction contamination. On the other hand, sinusoidal amplitude grating has the nonharmonic diffraction property, but it is too difficult to fabricate, especially for x-ray application. A novel nonharmonic diffraction grating named random position rectangle grating (RPRG) is proposed in this paper. Theoretical analysis and experiment results show that the RPRG is both higher order diffraction suppressing and not difficult to fabricate. Additionally, it is highly efficient; its first order absolute theoretical diffraction efficiency reaches 4.1%. Our result shows that RPRG is a novel tool for radiation diagnosis and monochromation. Project supported by the National Natural Science Foundation of China (Grant No. 11375160) and the National Science Instruments Major Project of China (Grant No. 2012YQ130125).

  20. 46 CFR 154.806 - Capacity of pressure relief valves.


    ... 46 Shipping 5 2010-10-01 2010-10-01 false Capacity of pressure relief valves. 154.806 Section 154... Equipment Cargo Vent Systems § 154.806 Capacity of pressure relief valves. Pressure relief valves for each... pressure above the set pressure of the relief valves: (a) The maximum capacity of an installed cargo...

  1. Laparoscopic Adhesiolysis and Relief of Chronic Pelvic Pain

    Nezhat, Farr R.; Crystal, Ruth Ann; Nezhat, Ceana H.


    Objective: To evaluate the short- and long-term results of laparoscopic enterolysis in patients with chronic pelvic pain following hysterectomy. Methods: Forty-eight patients were evaluated at time intervals from 2 weeks to 5 years after laparoscopic enterolysis. Patients were asked to rate postoperative relief of their pelvic pain as complete/near complete relief (80-100% pain relief), significant relief (50-80% pain relief), or less than 50% or no pain relief. Results: We found that after 2 to 8 weeks, 39% of patients reported complete/near complete pain relief, 33% reported significant pain relief, and 28% reported less than 50% or no pain relief. Six months to one year postlaparoscopy, 49% of patients reported complete/near complete pain relief, 15% reported significant pain relief, and 36% reported less than 50% or no pain relief. Two to five years after laparoscopic enterolysis, 37% of patients reported complete/near complete pain relief, 30% reported significant pain relief, and 33% reported less than 50% or no pain relief. Some patients required between 1 and 3 subsequent laparoscopic adhesiolysis. A total of 3 enterotomies and 2 cystotomies occurred, all of which were repaired laparoscopically. Conclusion: We conclude that laparoscopic enterolysis may offer significant long-term relief of chronic pelvic pain in some patients. PMID:11051185

  2. 48 CFR 252.229-7001 - Tax relief.


    ... 48 Federal Acquisition Regulations System 3 2010-10-01 2010-10-01 false Tax relief. 252.229-7001... Clauses 252.229-7001 Tax relief. As prescribed in 229.402-70(a), use the following clause: Tax Relief (JUN... or components intended to be imported in order to ensure that relief from import duties is obtained...

  3. 7 CFR 635.5 - Forms of relief.


    ... 7 Agriculture 6 2010-01-01 2010-01-01 false Forms of relief. 635.5 Section 635.5 Agriculture... AGRICULTURE LONG TERM CONTRACTING EQUITABLE RELIEF FROM INELIGIBILITY § 635.5 Forms of relief. (a) The Chief... land covered by the program; and (5) Receive such other equitable relief as determined to be...

  4. 37 CFR 41.120 - Notice of basis for relief.


    ... 37 Patents, Trademarks, and Copyrights 1 2010-07-01 2010-07-01 false Notice of basis for relief... Notice of basis for relief. (a) The Board may require a party to provide a notice stating the relief it requests and the basis for its entitlement to relief. The Board may provide for the notice to be maintained...

  5. 19 CFR 210.52 - Motions for temporary relief.


    ... 19 Customs Duties 3 2010-04-01 2010-04-01 false Motions for temporary relief. 210.52 Section 210... IMPORT TRADE ADJUDICATION AND ENFORCEMENT Temporary Relief § 210.52 Motions for temporary relief. Requests for temporary relief under section 337 (e) or (f) of the Tariff Act of 1930 shall be made through...

  6. 43 CFR 4.1367 - Request for temporary relief.


    ... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false Request for temporary relief. 4.1367... temporary relief. (a) Where review is requested pursuant to § 4.1362, any party may file a request for temporary relief at any time prior to a decision by an Administrative Law Judge, so long as the relief...

  7. 7 CFR 718.305 - Forms of relief.


    ... 7 Agriculture 7 2010-01-01 2010-01-01 false Forms of relief. 718.305 Section 718.305 Agriculture... Equitable Relief From Ineligibility § 718.305 Forms of relief. (a) The Administrator of FSA, Executive Vice... all or part of the land covered by the program; and (5) Receive such other equitable relief as...

  8. Encoded cell grating array in anti-counterfeit technology

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


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

  9. Study of all-polymer-based waveguide resonant gratings and their applications for optimization of second-harmonic generation

    Hoang Luong, Mai; Thanh Ngan Nguyen, Thi; Thanh Nguyen, Chi; Ledoux-Rak, Isabelle; Diep Lai, Ngoc


    We investigated theoretically and experimentally the optical properties of all-polymer-based one-dimensional waveguide resonant gratings (WRGs) and their important applications for the optimization of second-harmonic generation (SHG). We first studied the basic theory of the resonant modes of a simple grating-coupled waveguide realized on a material possessing a low refractive index contrast. The optical properties of any WRG were numerically simulated by using the finite-difference time domain method, performed by commercial Lumerical software. The polymer-based surface relief gratings were fabricated on azopolymer Disperse Red 1-Poly-Methyl-Methacrylate (DR1-PMMA) thin films by using the two-beam interference method and mass transport effect. Their experimental reflection spectra measured as a function of incident light wavelength are in good agreement with the theoretical predictions. We then demonstrated a first application of such a polymer-based WRG for nonlinear optics. Thanks to the strong local electrical field in the WRG, due to a guided-mode resonance condition, the SHG signal of an infrared light beam was strongly enhanced by a factor of 25 as compared to the result obtained in a sample without a grating.

  10. Gratings Fabricated on Flat Surfaces and Reproduced on Non-Flat Substrates

    Content, David; Iazikov, Dmitri; Mossberg, Thomas W.; Greiner, Christopher M.


    A method has been developed for fabricating gratings on flat substrates, and then reproducing the groove pattern on a curved (concave or convex) substrate and a corresponding grating device. First, surface relief diffraction grating grooves are formed on flat substrates. For example, they may be fabricated using photolithography and reactive ion etching, maskless lithography, holography, or mechanical ruling. Then, an imprint of the grating is made on a deformable substrate, such as plastic, polymer, or other materials using thermoforming, hot or cold embossing, or other methods. Interim stamps using electroforming, or other methods, may be produced for the imprinting process or if the same polarity of the grating image is required. The imprinted, deformable substrate is then attached to a curved, rigid substrate using epoxy or other suitable adhesives. The imprinted surface is facing away from the curved rigid substrate. As an alternative fabrication method, after grating is imprinted on the deformable substrate as described above, the grating may be coated with thin conformal conductive layer (for example, using vacuum deposition of gold). Then the membrane may be mounted over an opening in a pressured vessel in a manner of a membrane on a drum, grating side out. The pressure inside of the vessel may be changed with respect to the ambient pressure to produce concave or convex membrane surface. The shape of the opening may control the type of the surface curvature (for example, a circular opening would create spherical surface, oval opening would create toroidal surface, etc.). After that, well-known electroforming methods may be used to create a replica of the grating on the concave or convex membrane. For example, the pressure vessel assembly may be submerged into an electro-forming solution and negative electric potential applied to the metal coated membrane using an insulated wire. Positive electric potential may be then applied to a nickel or other metal

  11. Iridescence in Meat Caused by Surface Gratings

    Ali Kemal Yetisen


    Full Text Available The photonic structure of cut muscle tissues reveals that the well-ordered gratings diffract light, producing iridescent colours. Cut fibrils protruding from the muscle surface create a two-dimensional periodic array, which diffract light at specific wavelengths upon illumination. However, this photonic effect misleads consumers in a negative way to relate the optical phenomenon with the quality of the product. Here we discuss the fundamentals of this optical phenomenon and demonstrate a methodology for quantitatively measuring iridescence caused by diffraction gratings of muscle tissue surface of pork (Sus scrofa domesticus using reflection spectrophotometry. Iridescence was discussed theoretically as a light phenomenon and spectral measurements were taken from the gratings and monitored in real time during controlled drying. The findings show that the intensity of diffraction diminishes as the surface grating was dried with an air flow at 50 °C for 2 min while the diffracted light wavelength was at 585 ± 9 nm. Our findings indicate that the diffraction may be caused by a blazed surface grating. The implications of the study include providing guidelines to minimise the iridescence by altering the surface microstructure, and in consequence, removing the optical effect.

  12. Arc-Induced Long Period Fiber Gratings

    Gaspar Rego


    Full Text Available Long period fiber gratings produced by the electric arc technique have found an increasing interest by the scientific community due to their ease to fabricate, virtually enabling the inscription in any kind of fiber, low cost, and flexibility. In 2005 we have presented the first review on this subject. Since then, important achievements have been reached such as the identification of the mechanisms responsible for gratings formation, the type of symmetry, the conditions to increase fabrication reproducibility, and their inscription in the turning points with grating periods below 200 μm. Several interesting applications in the sensing area, including those sensors working in reflection, have been demonstrated and others are expected, namely, related to the monitoring of extreme temperatures, cryogenic and high temperatures, and high sensitivity refractometric sensors resulting from combining arc-induced gratings in the turning points and the deposition of thin films in the transition region. Therefore, due to its pertinence, in this paper we review the main achievements obtained concerning arc-induced long period fiber gratings, with special focus on the past ten years.

  13. Pain relief as an opponent process: a psychophysical investigation.

    Leknes, Siri; Brooks, Jonathan C W; Wiech, Katja; Tracey, Irene


    Relief from pain in humans is frequently measured by computing the reduction on an 11-point pain intensity scale. However, this definition of relief may be insufficient to capture the utility of pain relief for the individual. Based on pain literature and evidence from studies examining relief and reward, it is clear that pain relief is a broad concept comprising several factors, only one of which is pain intensity reduction. According to opponent process theory, all sensations consist of a primary process and a slow 'opponent process' of opposite valence, the purpose of which is to reduce the deviation from homeostatic balance. Here, opponent process theory provided a framework to explore the interaction between pain, relief and reward. We devised three psychophysical studies examining the temporal (Experiment I) and magnitude (Experiments I and II) relationships between pain severity and its subsequent relief. In Experiment III, we further manipulated the magnitude and pleasantness of relief experienced by applying innocuous cooling following noxious heat stimulation of capsaicin-sensitized skin. Results confirmed predictions from opponent process theory and showed that pain intensity reduction was significantly stronger than relief intensity ratings. Furthermore, continuous relief ratings appeared to reflect the speed of pain intensity reduction. Varying pain intensity parametrically confirmed that relief increases with pain intensity. That innocuous cooling following primary hyperalgesia intervention significantly increased the intensity, pleasantness and duration of relief provides further evidence that pain relief encapsulates more than a reduction in pain intensity. Importantly, the high relief pleasantness ratings confirmed the hypothesized link between relief and reward.

  14. III-Nitride grating grown on freestanding HfO2 gratings

    Wu Tong


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

  15. High-index-contrast subwavelength grating VCSEL

    Gilet, Philippe; Olivier, Nicolas; Grosse, Philippe


    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...

  16. Development of Aspherical Active Gratings at NSRRC

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


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

  17. Glovebox pressure relief and check valve

    Blaedel, K.L.


    This device is a combined pressure relief valve and check valve providing overpressure protection and preventing back flow into an inert atmosphere enclosure. The pressure relief is embodied by a submerged vent line in a mercury reservior, the releif pressure being a function of the submerged depth. The pressure relief can be vented into an exhaust system and the relieving pressure is only slightly influenced by the varying pressure in the exhaust system. The check valve is embodied by a ball which floats on the mercury column and contacts a seat whenever vacuum exists within the glovebox enclosure. Alternatively, the check valve is embodied by a vertical column of mercury, the maximum back pressure being a function of the height of the column of mercury.

  18. Theoretical analysis on x-ray cylindrical grating interferometer

    Cong, Wenxiang; Wang, Ge


    Grating interferometer is a state of art x-ray imaging approach, which can simultaneously acquire information of x-ray attenuation, phase shift, and small angle scattering. This approach is very sensitive to micro-structural variation and offers superior contrast resolution for biological soft tissues. The present grating interferometer often uses flat gratings, with serious limitations in the field of view and the flux of photons. The use of curved gratings allows perpendicular incidence of x-rays on the gratings, and gives higher visibility over a larger field of view than a conventional interferometer with flat gratings. In the study, we present a rigorous theoretical analysis of the self-imaging of curved transmission gratings based on Rayleigh-Sommerfeld diffraction. Numerical simulations have demonstrated the self-imaging phenomenon of cylindrical grating interferometer. The theoretical results are in agreement with the results of numerical simulations.

  19. Strongly Dispersive Transient Bragg Grating for High Harmonics

    Farrell, J.; Spector, L.S.; /SLAC, PULSE /Stanford U., Phys. Dept. /Stanford U., Appl. Phys. Dept.; Gaarde, M.B.; /SLAC, PULSE /Louisiana State U.; McFarland, B.K.; Bucksbaum, P.H.; Guhr, Markus; /SLAC, PULSE /Stanford U., Phys. Dept. /Stanford U., Appl. Phys. Dept.


    We create a transient Bragg grating in a high harmonic generation medium using two counterpropagating pulses. The Bragg grating disperses the harmonics in angle and can diffract a large bandwidth with temporal resolution limited only by the source size.

  20. Final report on bilateral comparison EURAMET.M.P-S10: Calibration of a SRG between 0.005 Pa and 1 Pa, and of a CDG between 0.5 Pa and 100 Pa

    Medina, Nieves


    Two national primary laboratories, CENAM (Mexico) and CEM (Spain), have compared the results of their pressure measurement capabilities by means of the calibration of a spinning rotor gauge (SRG) between 0.005 Pa and 1 Pa, and of a capacitance digital gauge (CDG) between 0.5 Pa and 100 Pa. The results of two calibrations made by CEM make it possible to conclude that the pressure transducers used for the comparison were appropriate for the purpose. The conclusions of supplementary comparison EURAMET.M.P-S10 are that all measurements are consistent and that there is agreement between the laboratories in the range compared. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database The final report has been peer-reviewed and approved for publication by EURAMET, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  1. Recent trends in the international relief system.

    Borton, J


    Since 1991 the international relief system has been undergoing a process of rapid and fundamental change associated with the end of the Cold War period. The principal changes concern (i) the international community's approach to national sovereignty and the 'right' of armed intervention in support of humanitarian objectives, and (ii) organisatwnal changes aimed at improving the coordination and effectiveness of the response by donor organisations and the United Nations. This paper describes these changes and attempts to place them in the context of earlier trends within the international relief system, notably the enhanced role of non-governmental organisations, which occurred during the 1980s.

  2. Polymeric waveguide Bragg grating filter using soft lithography

    Kocabas, Askin; Aydinli, Atilla


    We use the soft lithography technique to fabricate a polymeric waveguide Bragg grating filter. Master grating structure is patterned by e-beam lithography. Using an elastomeric stamp and capillary action, uniform grating structures with very thin residual layers are transferred to the UV curable polymer without the use of an imprint machine. The waveguide layer based on BCB optical polymer is fabricated by conventional optical lithography. This approach provides processing simplicity to fabricate Bragg grating filters.

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

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


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

  4. Multiwavelength optical scatterometry of dielectric gratings

    Yashina, Nataliya P.


    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.

  5. Novel algorithm for synthesis of fiber gratings

    Bo LV; Ming CHEN; Dan LU; Taorong GONG; Tangjun LI; Shuisheng JIAN


    A novel algorithm for the synthesis of fiber gratings is presented.For the first time we propose an effective optimal approach to construct a coupling coefficient function by employing 4th-order Runge-Kutta (R-K) analysis method for calculating the reflection spectra of fiber gratings.The numerical results show that with this proposed method, some required optical filters have been yielded with better features compared with other methods such as Gel'Fand-Levitan-Marchenko (GLM) algorithm.In addition, the performance of different interpolation functions particularly utilized in our algorithm, including linear-type, spline-type, and Hermit-type, are discussed in detail.

  6. Sangac interferometer on the holographic bragg grating

    Tikhonov, E A


    The ring interferometer with zero optical path difference known as Sagnac one is offered with a diffraction splitting of the entering light beam. As the beamsplitter, a transmission holographic Bragg grating is used. Conditions of normal operation of this interferometer achieve under the equal intensity of beam copies and the adjustable phase shift between them in its two interferometer shoulders. These conditions are met with the holographic grating, which provides the phase shift 180^0 on the central Bragg wavelength. Experimental approbation of the modified interferometer validates the expected results.

  7. Laser Trimming for Adjustment of Grating Offset in Phase-Shifted Fiber Grating Coupler for All-Optical Switching Application

    Hirohisa; Yokota; Yutaka; Sasaki


    We theoretically investigated laser trimming to adjust grating offset in phase-shifted fiber grating coupler (FGC) for all-optical switching application. It was clarified that the trimming made the extinction ratio higher in all-optical FGC switch.

  8. Emergency relief system design: The DIERS users group safety relief valve example problem

    Fisher, H.G. [Union Carbide Corp., South Charleston, WV (United States)


    Emergency relief system design involving two-phase flow is an evolving and complex technology. Aspects of alternative design techniques have been published. Well-documented, comprehensive design methods for safety relief valves, rupture disks and breather vents, however, are not readily available and example problems supported by data do not exist. Design Institute for Emergency Relief Systems (DIERS) Users Group members recently completed an example rating problem consisting of a safety relief valve mounted in a typical industrial configuration. Participants were asked to compute the flow through the device and to calculate the inlet pipe irreversible pressure loss and discharge pipe back pressure. Case studies involving various flows and physical conditions were formulated. A {open_quotes}Modified Delphi{close_quotes} technique was used to encourage participants to work until the {open_quotes}consensus{close_quotes} result was achieved. The exercise served to educate participants in the complexities and subtleties of emergency relief system design involving safety relief installations as compared to ideal nozzle calculations. All learned from the various calculation techniques used by others to solve the problem. Participants corrected parts of their computer codes and/or added procedures to address aspects of the problem. The present example problem is not supported by data. Available safety relief valve two-phase flow data suggest complexity not presently included in problem solutions. Future modification of the results may be required as additional considerations are incorporated into existing analytical methods and computer codes. 20 refs., 21 tabs.

  9. Light scanner based on a viscoelastic stretchable grating

    Simonov, A.N.; Akhzar-Mehr, O.; Vdovine, G.V.


    We present a new technique for light scanning by use of viscoelastic-based deformable phase diffraction gratings. Mechanical stretching of the grating permits control of its spatial period, and thus the orders of diffraction can be spatially deflected. In the experiments the viscoelastic gratings wi

  10. Liquid filling of photonic crystal fibres for grating writing

    Sørensen, Henrik Rokkjær; Canning, John; Lægsgaard, Jesper;


    liquid filling of photonic crystal fibres reduces the scattering from air–glass interfaces during Bragg grating writing in many layered photonic crystal fibres. Within experimental uncertainty, the grating index modulation of a grating written in germanium-doped photonic crystal fibre with 10 rings...

  11. Fabrication of Dammann Gratings Inside Glasses by a Femtosecond Laser

    NAKAYA Takayuki; QIU Jian-Rong; ZHOU Chang-He; HIRAO Kazuyuki


    @@ Dammann grating is useful in information technology as an optical splitter. It is usually fabricated through complicated processes. Here we report on the direct fabrication of a 6 × 6 Dammann grating in a silica glass by an 800nm femtosecond laser. We also discuss the relationship between diffraction efficiency of 1 × 2 Dammann grating and laser irradiation conditions.

  12. Light scanner based on a viscoelastic stretchable grating

    Simonov, A.N.; Akhzar-Mehr, O.; Vdovine, G.V.


    We present a new technique for light scanning by use of viscoelastic-based deformable phase diffraction gratings. Mechanical stretching of the grating permits control of its spatial period, and thus the orders of diffraction can be spatially deflected. In the experiments the viscoelastic gratings wi

  13. Off-plane x-ray reflection grating fabrication

    Peterson, Thomas J.; DeRoo, Casey T.; Marlowe, Hannah; McEntaffer, Randall L.; Miles, Drew M.; Tutt, James H.; Schultz, Ted B.


    Off-plane X-ray diffraction gratings with precision groove profiles at the submicron scale will be used in next generation X-ray spectrometers. Such gratings will be used on a current NASA suborbital rocket mission, the Off-plane Grating Rocket Experiment (OGRE), and have application for future grating missions. The fabrication of these gratings does not come without challenges. High performance off-plane gratings must be fabricated with precise radial grating patterns, optically at surfaces, and specific facet angles. Such gratings can be made using a series of common micro-fabrication techniques. The resulting process is highly customizable, making it useful for a variety of different mission architectures. In this paper, we detail the fabrication method used to produce high performance off-plane gratings and report the results of a preliminary qualification test of a grating fabricated in this manner. The grating was tested in the off-plane `Littrow' configuration, for which the grating is most efficient for a given diffraction order, and found to achieve 42% relative efficiency in the blaze order with respect to all diffracted light.

  14. Theory of optimal beam splitting by phase gratings. I. One-dimensional gratings.

    Romero, Louis A; Dickey, Fred M


    We give an analytical basis for the theory of optimal beam splitting by one-dimensional gratings. In particular, we use methods from the calculus of variations to derive analytical expressions for the optimal phase function.

  15. Relief for surviving relatives following a suicide.

    Oud, MJT; de Groot, MH


    Relief for surviving relatives following a suicide. - After the suicide of a 43-year-old woman with known depression, a 41-year-old paraplegic man who recently developed diarrhoea and a 41-year-old woman with probable depression with symptoms of psychosis, the general practitioners of the surviving

  16. Relief for surviving relatives following a suicide.

    Oud, MJT; de Groot, MH


    Relief for surviving relatives following a suicide. - After the suicide of a 43-year-old woman with known depression, a 41-year-old paraplegic man who recently developed diarrhoea and a 41-year-old woman with probable depression with symptoms of psychosis, the general practitioners of the surviving

  17. What sets topographic relief in extensional footwalls?

    Densmore, Alexander L.; Dawers, Nancye H.; Gupta, Sanjeev; Guidon, Roman


    We use three large normal fault arrays in the northeastern Basin and Range Province, western United States, to document catchment development and relief production during fault growth. Fault slip and slip rates increase systematically along strike from zero at the fault tips. Catchment relief and across-strike range width both increase as slip accumulates but reach maximum values at a distance of ˜15 km from the fault tips and remain uniform along strike over much of the footwalls. Catchment outlet spacing also increases away from the fault tips but does not reach a uniform value and may vary by a factor of 5 6 along strike. We infer that catchments first elongate in the across-strike direction as slip accumulates and the range half-width increases. Once the half-width reaches its maximum value, continued catchment growth is possible only by along-strike capture, which increases outlet spacing but not relief. The close correspondence between catchment relief and range half-width suggests that geomorphically limited hillslope and channel gradients are achieved within the 15 km tip zone. Thus, the limiting factor in footwall development is the width of the range, which is controlled by two external agents: the geometry and spacing of the major faults, and the elevations of base level on both flanks.

  18. 75 FR 75091 - Mortgage Assistance Relief Services


    ... marketing of MARS, including misrepresentations regarding the services MARS providers will perform and... marketing to offer newly-minted forms of mortgage relief--for example, the possibility of entering a short...:// . \\59\\ See State Bar of Cal., Ethics Alert: Legal...

  19. A node architecture for disaster relief networking

    Hoeksema, F.W.; Heskamp, M.; Schiphorst, R.; Slump, C.H.


    In this paper we present node architecture for a personal node in a cognitive ad-hoc disaster relief network. This architecture is motivated from the network system requirements, especially single-hop distance and jamming-resilience requirements. It is shown that the power consumption of current-day

  20. Smart photogalvanic running-grating interferometer

    Kukhtarev, N. V.; Kukhtareva, T.; Edwards, M. E.


    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 of...

  1. Gratings in plasmonic V-groove waveguides

    Smith, Cameron; Cuesta, Irene Fernandez; Kristensen, Anders


    We introduce visible light optical gratings to surface plasmon V-groove waveguides. Gradient e-beam dosage onto silicon stamp enables structuring V-grooves of varying depth. Nanoimprint lithography maintains a Λ=265 nm corrugation for gold surface devices....

  2. Speed enhancement in VCSELs employing grating mirrors

    Chung, Il-Sug; Mørk, Jesper


    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...

  3. Exciton-polaritons in Bragg gratings

    Creatore, C [Department of Physics ' A. Volta' , Universita di Pavia, via Bassi 6, I-27100, Pavia (Italy); Mouchliadis, L; Langbein, W [School of Physics and Astronomy, Cardiff University, The Parade, CF24 3AA, Cardiff (United Kingdom); Biancalana, F [Max Planck Institute for the Science of Light, Guenther-Scharowsky-Str. 1/Bau 24, 91058 Erlangen (Germany); Osborne, S, E-mail: creatore@fisicavolta.unipv.i [Tyndall National Institute, Lee Maltings, Prospect Row, Cork (Ireland)


    We study the strong coupling between photons and bulk excitons in a one-dimensional Bragg grating. The dispersion of the resulting Bragg-polariton states resembles the dispersion of quantum-well microcavity polaritons. We report on a parametric scattering process at two 'magic frequencies' occurring due to the strong excitonic nonlinearity.

  4. Hybrid grating reflectors: Origin of ultrabroad stopband

    Park, Gyeong Cheol; Taghizadeh, Alireza; Chung, Il-Sug, E-mail: [DTU Fotonik, Department of Photonics Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark)


    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.

  5. Gratings in plasmonic V-groove waveguides

    Smith, Cameron; Cuesta, Irene Fernandez; Kristensen, Anders


    We introduce visible light optical gratings to surface plasmon V-groove waveguides. Gradient e-beam dosage onto silicon stamp enables structuring V-grooves of varying depth. Nanoimprint lithography maintains a Λ=265 nm corrugation for gold surface devices....

  6. Undergraduate Experiment with Fractal Diffraction Gratings

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


    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…

  7. Concave diffraction gratings fabricated with planar lithography

    Grabarnik, S.; Emadi, A.; Wu, H.; De Graaf, G.; Wolffenbuttel, R.F.


    This paper reports on the development and validation of a new technology for the fabrication of variable line-spacing non-planar diffraction gratings to be used in compact spectrometers. The technique is based on the standard lithographic process commonly used for pattern transfer onto a flat substr

  8. Refuge alternatives relief valve testing and design.

    Lutz, T J; Bissert, P T; Homce, G T; Yonkey, J A


    The U.S. National Institute for Occupational Safety and Health (NIOSH) has been researching refuge alternatives (RAs) since 2007. RAs typically have built-in pressure relief valves (PRVs) to prevent the unit from reaching unsafe pressures. The U.S. Mine Safety and Health Administration requires that these valves vent the chamber at a maximum pressure of 1.25 kPa (0.18 psi, 5.0 in. H2O), or as specified by the manufacturer, above mine atmospheric pressure in the RA. To facilitate PRV testing, an instrumented benchtop test fixture was developed using an off-the-shelf centrifugal blower and ductwork. Relief pressures and flow characteristics were measured for three units: (1) a modified polyvinyl chloride check valve, (2) an off-the-shelf brass/cast-iron butterfly check valve and (3) a commercially available valve that was designed specifically for one manufacturer's steel prefabricated RAs and had been adapted for use in one mine operator's built-in-place RA. PRVs used in tent-style RAs were not investigated. The units were tested with different modifications and configurations in order to check compliance with Title 30 Code of Federal Regulations, or 30 CFR, regulations. The commercially available relief valve did not meet the 30 CFR relief pressure specification but may meet the manufacturer's specification. Alternative valve designs were modified to meet the 30 CFR relief pressure specification, but all valve designs will need further design research to examine survivability in the event of a 103 kPa (15.0 psi) impulse overpressure during a disaster.

  9. Optical position encoder based on four-section diffraction grating

    Zherdev, A. Y.; Odinokov, S. B.; Lushnikov, D. S.; Markin, V. V.; Gurylev, O. A.; Shishova, M. V.


    Optical position encoder consists of movable coding grating and fixed analyzing grating. Light passing and diffracting through these two gratings creates interference signal on optical detector. Decoding of interference signal phase allows to determinate current position. Known optical position encoders use several accurate adjusted optical channels and detectors to gather several signals with different phase for higher encoder accuracy. We propose to use one optical channel with several-section analyzing diffraction grating for this purpose to simplify optical scheme and adjusting requirements. Optical scheme of position encoder based on four-section analyzing diffraction grating is developed and described in this paper.

  10. Metrology measurements for large-aperture VPH gratings

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


    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.

  11. Field analysis of two-dimensional integrated optical gratings

    Borsboom, P.-P.; Frankena, H. J.


    A rigorous technique to determine the field scattered by a two-dimensional rectangular grating made up of many corrugations was developed. In this method, the grating was deemed as a sequence of two types of waveguide sections, alternatingly connected by step discontinuities. A matrix was derived that described the entire rectangular grating by integrating the separate steps and waveguide sections. With the proposed technique, several configuration were analyzed. The obtained results showed good consistency with the consequences of previous studies. Furthermore, to examine the numerical stability of the proposed method, the length of the grating was increased and obtained results for a grating with 100 periods.

  12. Field analysis of two-dimensional focusing grating couplers

    Borsboom, P.-P.; Frankena, H. J.


    A different technique was developed by which several two-dimensional dielectric optical gratings, consisting 100 or more corrugations, were treated in a numerical reliable approach. The numerical examples that were presented were restricted to gratings made up of sequences of waveguide sections symmetric about the x = 0 plane. The newly developed method was effectively used to investigate the field produced by a two-dimensional focusing grating coupler. Focal-region fields were determined for three symmetrical gratings with 19, 50, and 124 corrugations. For focusing grating coupler with limited length, high-frequency intensity variations were noted in the focal region.

  13. Fiber-bragg grating-loop ringdown method and apparatus

    Wang, Chuji


    A device comprising a fiber grating loop ringdown (FGLRD) system of analysis is disclosed. A fiber Bragg grating (FBG) or Long-Period grating (LPG) written in a section of single mode fused silica fiber is incorporated into a fiber loop. By utilizing the wing areas of the gratings' bandwidth as a wavelength dependent attenuator of the light transmission, a fiber grating loop ringdown concept is formed. One aspect of the present invention is temperature sensing, which has been demonstrated using the disclosed device. Temperature measurements in the areas of accuracy, stability, high temperature, and dynamic range are also described.

  14. Fundamental limit of light trapping in grating structures

    Yu, Zongfu


    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.

  15. Nanostructure Diffraction Gratings for Integrated Spectroscopy and Sensing

    Guo, Junpeng (Inventor)


    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.

  16. Topographic and Bathymetric Shaded Relief of North America - Direct Download

    U.S. Geological Survey, Department of the Interior — The Topographic and Bathymetric Shaded Relief of North America map layer shows depth and elevation ranges using colors, with relief enhanced by shading. The image...

  17. Medications for Pain Relief during Labor and Delivery

    ... FAQ086 LABOR, DELIVERY, AND POSTPARTUM CARE Medications for Pain Relief During Labor and Delivery • What are the types ... an epidural”) is the most common type of pain relief used during labor and delivery in the United ...

  18. Bathymetric Shaded Relief of North America - Direct Download

    U.S. Geological Survey, Department of the Interior — The Bathymetric Shaded Relief of North America map layer shows depth ranges using colors, with relief enhanced by shading. The image was derived from the National...

  19. 100-Meter Resolution Color Shaded Relief of Hawaii - Direct Download

    U.S. Geological Survey, Department of the Interior — The Color Shaded Relief of Hawaii map layer is a 100-meter resolution color-sliced elevation image of Hawaii, with relief shading added to accentuate terrain...

  20. 100-Meter Resolution Color Shaded Relief of Alaska - Direct Download

    U.S. Geological Survey, Department of the Interior — The Color Shaded Relief of Alaska map layer is a 100-meter resolution color-sliced elevation image of Alaska, with relief shading added to accentuate terrain...

  1. 100-Meter Resolution Grayscale Shaded Relief of Hawaii - Direct Download

    U.S. Geological Survey, Department of the Interior — The Grayscale Shaded Relief of Hawaii map layer is a 100-meter resolution grayscale shaded relief image of Hawaii, in an Albers Equal-Area Conic projection. Shaded...

  2. 100-Meter Resolution Grayscale Shaded Relief of Alaska - Direct Download

    U.S. Geological Survey, Department of the Interior — The Grayscale Shaded Relief of Alaska map layer is a 100-meter resolution grayscale shaded relief image of Alaska, in an Albers Equal-Area Conic projection. Shaded...

  3. Mechanical Designs for Relief Valves for Cryogenic Apparatuses and Installations

    CERN. Geneva


    There are also pressure relief valves with warm seat available on which the set pressure is based on an adjustment of forces by permanent magnets. Pressure vessel rules allows also the choice for an active triggered pressure relief valve (Cont...

  4. Digital Shaded-Relief Image of Alaska

    Riehle, J.R.; Fleming, Michael D.; Molnia, B.F.; Dover, J.H.; Kelley, J.S.; Miller, M.L.; Nokleberg, W.J.; Plafker, George; Till, A.B.


    Introduction One of the most spectacular physiographic images of the conterminous United States, and the first to have been produced digitally, is that by Thelin and Pike (USGS I-2206, 1991). The image is remarkable for its crispness of detail and for the natural appearance of the artificial land surface. Our goal has been to produce a shaded-relief image of Alaska that has the same look and feel as the Thelin and Pike image. The Alaskan image could have been produced at the same scale as its lower 48 counterpart (1:3,500,000). But by insetting the Aleutian Islands into the Gulf of Alaska, we were able to print the Alaska map at a larger scale (1:2,500,000) and about the same physical size as the Thelin and Pike image. Benefits of the 1:2,500,000 scale are (1) greater resolution of topographic features and (2) ease of reference to the U.S. Geological Survey (USGS) (1987) Alaska Map E and the statewide geologic map (Beikman, 1980), which are both 1:2,500,000 scale. Manually drawn, shaded-relief images of Alaska's land surface have long been available (for example, Department of the Interior, 1909; Raisz, 1948). The topography depicted on these early maps is mainly schematic. Maps showing topographic contours were first available for the entire State in 1953 (USGS, 1:250,000) (J.H. Wittmann, USGS, written commun., 1996). The Alaska Map E was initially released in 1954 in both planimetric (revised in 1973 and 1987) and shaded-relief versions (revised in 1973, 1987, and 1996); topography depicted on the shaded-relief version is based on the 1:250,000-scale USGS topographic maps. Alaska Map E was later modified to include hypsometric tinting by Raven Maps and Images (1989, revised 1993) as copyrighted versions. Other shaded-relief images were produced for The National Geographic Magazine (LaGorce, 1956; 1:3,000,000) or drawn by Harrison (1970; 1:7,500,000) for The National Atlas of the United States. Recently, the State of Alaska digitally produced a shaded-relief image

  5. A fiber-integrated optical component fabricated via photopolymerization: Mode-selective grating coupler

    Sümer, Can; Dinleyici, M. Salih


    We demonstrate a mode-selective directional coupler based on a grating structure, which is fabricated by laser direct-writing on a photopolymer thin film. The device is implemented on the flat planar surface of the D-Fiber, enabling fiber integration, where an Acrylamide/Polyvinyl Alcohol based photopolymer material is used in the fabrication of the device. While the refractive index modulation properties of the polymer material are well known, surface relief and corrugation properties due to photopolymerization are investigated in this study. Theoretical model of the device is presented together with the optimization and simulation results of the final device; experimental results have been found to be in good agreement with simulations.

  6. First order Bragg grating filters in silicon on insulator waveguides

    Waugh, Peter Michael


    The subject of this project is the design; analysis, fabrication and characterisation of first order Bragg Grating optical filters in Silicon-on-Insulator (SOI) planar waveguides. It is envisaged that this work will result in the possibility of Bragg Grating filters for use in Silicon Photonics. It is the purpose of the work to create as far as is possible flat surface waveguides so as to facilitate Thermo-Optic tuning and also the incorporation into rib-waveguide Silicon Photonics. The spectral response of the shallow Bragg Gratings was modelled using Coupled Mode Theory (CMT) by way of RSoft Gratingmod TM. Also the effect of having a Bragg Grating with alternate layers of refractive index of 1.5 and 3.5 was simulated in order to verify that Silica and Silicon layered Bragg Gratings could be viable. A series of Bragg Gratings were patterned on 1.5 micron SOI at Philips in Eindhoven, Holland to investigate the variation of grating parameters with a) the period of the gratings b) the mark to space ratio of the gratings and c) the length of the region converted to Bragg Gratings (i.e. the number of grating period repetitions). One set of gratings were thermally oxidised at Philips in Eindhoven and another set were ion implanted with Oxygen ions at the Ion Beam Facility, University of Surrey, England. The gratings were tested and found to give transmission minima at approximately 1540 nanometres and both methods of creating flat surfaces were found to give similar minima. Atomic Force Microscopy was applied to the grating area of the as-implanted samples in the Advanced Technology Institute, University of Surrey, which were found to have surface undulations in the order of 60 nanometres.

  7. 46 CFR 154.519 - Piping relief valves.


    ... 46 Shipping 5 2010-10-01 2010-10-01 false Piping relief valves. 154.519 Section 154.519 Shipping... Process Piping Systems § 154.519 Piping relief valves. (a) The liquid relief valve that protects the cargo piping system from liquid pressure exceeding the design pressure must discharge into: (1) A cargo...

  8. 49 CFR 179.15 - Pressure relief devices.


    ... 49 Transportation 2 2010-10-01 2010-10-01 false Pressure relief devices. 179.15 Section 179.15... Design Requirements § 179.15 Pressure relief devices. Except for DOT Class 106, 107, 110, and 113 tank cars, tanks must have a pressure relief device, made of material compatible with the lading,...

  9. 46 CFR 154.912 - Inerted spaces: Relief devices.


    ... 46 Shipping 5 2010-10-01 2010-10-01 false Inerted spaces: Relief devices. 154.912 Section 154.912... Atmospheric Control in Cargo Containment Systems § 154.912 Inerted spaces: Relief devices. Inerted spaces must be fitted with relief valves, rupture discs, or other devices specially approved by the...

  10. 49 CFR 179.500-12 - Pressure relief devices.


    ... 49 Transportation 2 2010-10-01 2010-10-01 false Pressure relief devices. 179.500-12 Section 179... and 107A) § 179.500-12 Pressure relief devices. (a) Tank shall be equipped with one or more pressure relief devices of approved type and discharge area, mounted on the cover or threaded into the...

  11. 49 CFR 179.300-15 - Pressure relief devices.


    ... 49 Transportation 2 2010-10-01 2010-10-01 false Pressure relief devices. 179.300-15 Section 179... Pressure relief devices. (a) Unless prohibited in part 173 of this subchapter, tanks shall be equipped with one or more relief devices of approved type, made of metal not subject to rapid deterioration by...

  12. 21 CFR 358.310 - Ingrown toenail relief active ingredient.


    ... 21 Food and Drugs 5 2010-04-01 2010-04-01 false Ingrown toenail relief active ingredient. 358.310... (CONTINUED) DRUGS FOR HUMAN USE MISCELLANEOUS EXTERNAL DRUG PRODUCTS FOR OVER-THE-COUNTER HUMAN USE Ingrown Toenail Relief Drug Products § 358.310 Ingrown toenail relief active ingredient. The active ingredient...

  13. 46 CFR 98.25-60 - Safety relief valves.


    ... 46 Shipping 4 2010-10-01 2010-10-01 false Safety relief valves. 98.25-60 Section 98.25-60 Shipping... § 98.25-60 Safety relief valves. (a) Each tank shall be fitted with two or more approved safety relief valves, designed, constructed, and flow-tested for capacity in conformance with subpart 162.018...

  14. 46 CFR 154.1846 - Relief valves: Changing set pressure.


    ... 46 Shipping 5 2010-10-01 2010-10-01 false Relief valves: Changing set pressure. 154.1846 Section... Relief valves: Changing set pressure. The master shall: (a) Supervise the changing of the set pressure of relief valves under § 154.802(b); (b) Enter the change of set pressure in the vessel's log; and...

  15. 27 CFR 24.158 - Extent of relief.


    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Extent of relief. 24.158... Extent of relief. (a) General. The surety on any bond required by this part who has filed a notice for relief from liability as provided in § 24.157 will be relieved from liability under bond as set forth in...

  16. 30 CFR 847.16 - Civil actions for relief.


    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Civil actions for relief. 847.16 Section 847.16... relief. (a) Under section 521(c) of the Act, we, the regulatory authority, may request the Attorney General to institute a civil action for relief whenever you, the permittee, or your agent— (1) Violate or...

  17. 19 CFR 171.3 - Oral presentations seeking relief.


    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Oral presentations seeking relief. 171.3 Section... OF THE TREASURY (CONTINUED) FINES, PENALTIES, AND FORFEITURES Application for Relief § 171.3 Oral presentations seeking relief. (a) For violation of section 592 or section 593A. If the penalty incurred is for a...

  18. 7 CFR 900.70 - Applications for interim relief.


    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Applications for interim relief. 900.70 Section 900.70... Applications for interim relief. (a) Filing the application. A person who has filed a petition pursuant to... the relief is requested, including any facts showing irreparable injury. The application must be...

  19. 19 CFR 172.2 - Petition for relief.


    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Petition for relief. 172.2 Section 172.2 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY... Relief § 172.2 Petition for relief. (a) To whom addressed. Petitions for the cancellation of any claim...

  20. 47 CFR 52.19 - Area code relief.


    ... 47 Telecommunication 3 2010-10-01 2010-10-01 false Area code relief. 52.19 Section 52.19... Administration § 52.19 Area code relief. (a) State commissions may resolve matters involving the introduction of... whether area code relief will take the form of a geographic split, an overlay area code, or a boundary...

  1. 29 CFR 1601.23 - Preliminary or temporary relief.


    ... 29 Labor 4 2010-07-01 2010-07-01 false Preliminary or temporary relief. 1601.23 Section 1601.23... Employment Practices § 1601.23 Preliminary or temporary relief. (a) In the interest of the expeditious... subdivision, any recommendation for preliminary or temporary relief shall be transmitted directly to the...

  2. 18 CFR 1308.11 - Contractor's request for relief.


    ... for relief. 1308.11 Section 1308.11 Conservation of Power and Water Resources TENNESSEE VALLEY AUTHORITY CONTRACT DISPUTES Contracting Officers § 1308.11 Contractor's request for relief. Any request for relief which a Contractor believes is due under a contract shall be submitted to the Contracting Officer...

  3. 50 CFR 11.12 - Petition for relief.


    ... 50 Wildlife and Fisheries 1 2010-10-01 2010-10-01 false Petition for relief. 11.12 Section 11.12... PROCEDURES Assessment Procedure § 11.12 Petition for relief. If the respondent so chooses he may ask that no... the charge and the Director's allegations of facts, by filing a petition for relief (hereinafter...

  4. 49 CFR 178.345-10 - Pressure relief.


    ... 49 Transportation 2 2010-10-01 2010-10-01 false Pressure relief. 178.345-10 Section 178.345-10... Specifications for Containers for Motor Vehicle Transportation § 178.345-10 Pressure relief. (a) Each cargo tank... applicable individual specification. The pressure and vacuum relief system must be designed to operate and...

  5. 12 CFR 268.501 - Remedies and relief.


    ... 12 Banks and Banking 3 2010-01-01 2010-01-01 false Remedies and relief. 268.501 Section 268.501... RULES REGARDING EQUAL OPPORTUNITY Remedies and Enforcement § 268.501 Remedies and relief. (a) When the... employee has been discriminated against, the Board shall provide full relief which shall include the...

  6. 49 CFR 1115.5 - Petitions for other relief.


    ... 49 Transportation 8 2010-10-01 2010-10-01 false Petitions for other relief. 1115.5 Section 1115.5... OF TRANSPORTATION RULES OF PRACTICE APPELLATE PROCEDURES § 1115.5 Petitions for other relief. (a) A... desired relief must be stated in the petition, and the petition must be filed not less than 10 days prior...

  7. 31 CFR 306.111 - Procedure for applying for relief.


    ... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false Procedure for applying for relief... GOVERNING U.S. SECURITIES Relief for Loss, Theft, Destruction, Mutilation, or Defacement of Securities § 306.111 Procedure for applying for relief. Prompt report of the loss, theft, destruction, mutilation or...

  8. 49 CFR 178.347-4 - Pressure relief.


    ... 49 Transportation 2 2010-10-01 2010-10-01 false Pressure relief. 178.347-4 Section 178.347-4... Specifications for Containers for Motor Vehicle Transportation § 178.347-4 Pressure relief. (a) Each cargo tank must be equipped with a pressure and vacuum relief system in accordance with § 178.345-10 and this...

  9. 49 CFR 601.41 - Petitions for relief.


    ... 49 Transportation 7 2010-10-01 2010-10-01 false Petitions for relief. 601.41 Section 601.41... Transportation Systems § 601.41 Petitions for relief. In the case of a national or regional emergency or disaster... for temporary relief from the provisions of any policy statement, circular, guidance document or rule. ...

  10. 49 CFR 178.346-3 - Pressure relief.


    ... 49 Transportation 2 2010-10-01 2010-10-01 false Pressure relief. 178.346-3 Section 178.346-3... Specifications for Containers for Motor Vehicle Transportation § 178.346-3 Pressure relief. (a) Each cargo tank must be equipped with a pressure relief system in accordance with § 178.345-10 and this section. (b...

  11. 26 CFR 1.6015-4 - Equitable relief.


    ... 26 Internal Revenue 13 2010-04-01 2010-04-01 false Equitable relief. 1.6015-4 Section 1.6015-4...) INCOME TAXES Tax Returns Or Statements § 1.6015-4 Equitable relief. (a) A requesting spouse who files a joint return for which a liability remains unpaid and who does not qualify for full relief under § 1...

  12. 29 CFR 1614.501 - Remedies and relief.


    ... 29 Labor 4 2010-07-01 2010-07-01 false Remedies and relief. 1614.501 Section 1614.501 Labor... EMPLOYMENT OPPORTUNITY Remedies and Enforcement § 1614.501 Remedies and relief. (a) When an agency, or the... discriminated against, the agency shall provide full relief which shall include the following elements in...

  13. 37 CFR 41.204 - Notice of basis for relief.


    ... 37 Patents, Trademarks, and Copyrights 1 2010-07-01 2010-07-01 false Notice of basis for relief... § 41.204 Notice of basis for relief. (a) Priority statement. (1) A party may not submit evidence of its... the precise relief sought. (c) Filing and service. The Board will set the times for filing and serving...

  14. 46 CFR 560.3 - Petitions for relief.


    ... 46 Shipping 9 2010-10-01 2010-10-01 false Petitions for relief. 560.3 Section 560.3 Shipping... PORTS § 560.3 Petitions for relief. (a) Filing. (1) Any owner or operator of a liner, bulk, tramp or... between foreign ports has been, or will be, unduly impaired may file a written petition for relief under...

  15. 19 CFR 171.1 - Petition for relief.


    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Petition for relief. 171.1 Section 171.1 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY (CONTINUED) FINES, PENALTIES, AND FORFEITURES Application for Relief § 171.1 Petition for relief. (a) To whom...

  16. Libraries and information provision for African relief

    Elsemieke Wishart


    Full Text Available This research article explores the concept that libraries as communication centres in sub-Saharan Africa can play a vital role in bringing poverty relief by providing greater access to information through modern technology. It discusses the patrons who can benefit from community information centres and explores their particular needs. I have researched how modern tools like the Internet, computers, e-readers and cell phones can bring valuable information to impoverished citizens. My research was conducted through reading research papers using article databases, books and Internet websites. The future for libraries in sub-Saharan Africa is bright, as new technology opens up vast opportunities to share information in a way that is accessible, affordable and adaptable to the needs of the African people. I recommend that librarians and relief organisations in Southern Africa seriously consider using modern technology to provide information that will empower its citizens.

  17. Computational analysis of aircraft pressure relief doors

    Schott, Tyler

    Modern trends in commercial aircraft design have sought to improve fuel efficiency while reducing emissions by operating at higher pressures and temperatures than ever before. Consequently, greater demands are placed on the auxiliary bleed air systems used for a multitude of aircraft operations. The increased role of bleed air systems poses significant challenges for the pressure relief system to ensure the safe and reliable operation of the aircraft. The core compartment pressure relief door (PRD) is an essential component of the pressure relief system which functions to relieve internal pressure in the core casing of a high-bypass turbofan engine during a burst duct over-pressurization event. The successful modeling and analysis of a burst duct event are imperative to the design and development of PRD's to ensure that they will meet the increased demands placed on the pressure relief system. Leveraging high-performance computing coupled with advances in computational analysis, this thesis focuses on a comprehensive computational fluid dynamics (CFD) study to characterize turbulent flow dynamics and quantify the performance of a core compartment PRD across a range of operating conditions and geometric configurations. The CFD analysis was based on a compressible, steady-state, three-dimensional, Reynolds-averaged Navier-Stokes approach. Simulations were analyzed, and results show that variations in freestream conditions, plenum environment, and geometric configurations have a non-linear impact on the discharge, moment, thrust, and surface temperature characteristics. The CFD study revealed that the underlying physics for this behavior is explained by the interaction of vortices, jets, and shockwaves. This thesis research is innovative and provides a comprehensive and detailed analysis of existing and novel PRD geometries over a range of realistic operating conditions representative of a burst duct over-pressurization event. Further, the study provides aircraft

  18. Relief Evolution in Tectonically Active Mountain Ranges

    Whipple, Kelin X.


    The overall aims of this 3-yr project, as originally proposed were to: (1) investigate quantitatively the roles of fluvial and glacial erosion in the evolution of relief in mountainous regions, and (2) test rigorously the quality and accuracy of SRTM topographic data in areas of rugged relief - both the most challenging and of greatest interest to geomorphic, neotectonic, and hazards applications. Natural laboratories in both the western US and the Southern Alps of New Zealand were identified as most promising. The project has been both successful and productive, despite the fact that no SRTM data for our primary field sites in New Zealand were released on the time frame of the work effort. Given the delayed release of SRTM data, we pursued the scientific questions of the roles of fluvial and, especially, glacial erosion in the evolution of relief in mountainous regions using available digital elevation models (DEMs) for the Southern Alps of New Zealand (available at both 25m and 50m pixel sizes), and USGS 10m and 30m DEMs within the Western US. As emphasized in the original proposal, we chose the emphasis on the role of glacial modification of topographic relief because there has been little quantitative investigation of glacial erosion processes at landscape scale. This is particularly surprising considering the dramatic sculpting of most mid- and high-latitude mountain ranges, the prodigious quantities of glacially-derived sediment in terrestrial and marine basins, and the current cross-disciplinary interest in the role of denudational processes in orogenesis and the evolution of topography in general. Moreover, the evolution of glaciated landscapes is not only a fundamental problem in geomorphology in its own right, but also is at the heart of the debate over Late Cenozoic linkages between climate and tectonics.

  19. Electromagnetically induced grating with Rydberg atoms

    Asghar, Sobia; Ziauddin, Qamar, Shahid; Qamar, Sajid


    We present a scheme to realize electromagnetically induced grating in an ensemble of strongly interacting Rydberg atoms, which act as superatoms due to the dipole blockade mechanism. The ensemble of three-level cold Rydberg-dressed (87Rb) atoms follows a cascade configuration where a strong standing-wave control field and a weak probe pulse are employed. The diffraction intensity is influenced by the strength of the probe intensity, the control field strength, and the van der Waals (vdW) interaction. It is noticed that relatively large first-order diffraction can be obtained for low-input intensity with a small vdW shift and a strong control field. The scheme can be considered as an amicable solution to realize the atomic grating at the microscopic level, which can provide background- and dark-current-free diffraction.

  20. Stationary Light Pulses without Bragg Gratings

    Lin, Yen-Wei; Peters, Thorsten; Liao, Wen-Te; Cho, Hung-Wen; Guan, Pei-Chen; Yu, Ite A


    The underlying mechanism of the stationary light pulse (SLP) was identified as a band gap being created by a Bragg grating formed by two counter-propagating coupling fields of similar wavelength. Here we present a more general view of the formation of SLPs, namely several balanced four-wave mixing processes sharing the same ground-state coherence. Utilizing this new concept we report the first experimental observation of a bichromatic SLP at wavelengths for which no Bragg grating can be established. We also demonstrate the production of a SLP directly from a propagating light pulse without prior storage. Being easily controlled externally makes SLPs a very versatile tool for low-light-level nonlinear optics and quantum information manipulation.

  1. 3D measurement using circular gratings

    Harding, Kevin


    3D measurement using methods of structured light are well known in the industry. Most such systems use some variation of straight lines, either as simple lines or with some form of encoding. This geometry assumes the lines will be projected from one side and viewed from another to generate the profile information. But what about applications where a wide triangulation angle may not be practical, particularly at longer standoff distances. This paper explores the use of circular grating patterns projected from a center point to achieve 3D information. Originally suggested by John Caulfield around 1990, the method had some interesting potential, particularly if combined with alternate means of measurement from traditional triangulation including depth from focus methods. The possible advantages of a central reference point in the projected pattern may offer some different capabilities not as easily attained with a linear grating pattern. This paper will explore the pros and cons of the method and present some examples of possible applications.

  2. 130-nm tunable grating-mirror VCSEL

    Chung, Il-Sug; Mørk, Jesper


    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 configurat......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...... configuration instead of the extended cavity configuration can bring 130-nm tuning range around 1330-nm wavelength. The air-coupled cavity is known to reduce the quantum confinement factor in VCSELs, increasing threshold. In our air-coupled cavity HCG VCSEL case, the very short power penetration length...

  3. Strong Optical Confinement between Flat Dielectric Gratings

    Li, Jingjing; Fiorentino, Marco; Beausoleil, Raymond G


    We present a novel type of optical micro-cavity based on a Fabry-Perot resonance between parallel high contrast gratings with non-periodic patterns. Tight lateral confinement is obtained via the phase front distortion properties of these gratings. In such cavities, energy stored in the optical field resides primarily in free space, therefore is readily accessible to particles (atoms, molecules, nanocrystals, etc.) for sensing, trapping, or spectroscopic applications. We describe the physics of these resonators, and propose a design method based on stochastic optimization. We present numerical simulations of two and three dimensional cavities that have diffraction-limited mode volumes with quality factors in the range of $10^4$--$10^6$. The cavity has a purely planar geometry and can be fabricated in silicon for near-infrared applications using standard CMOS processes. These ideas can be extended to the visible domain using commonly available III-V materials.

  4. Optical Properties of Topological Insulator Bragg Gratings

    Crosse, J A


    Using the transfer matrix formalism, we study the transmission properties of a Bragg grating constructed from a layered axionic material. Such a material can be realized by a topological insulator subject to a time-symmetry breaking perturbation, such as an external magnetic field or surface magnetic impurities. Whilst the reflective properties of the structure are only negligibly changed by the presence of the axionic material, the grating induces Faraday and Kerr rotations in the transmitted and reflected light, respectively. These rotations are proportional to the number of layers and the strength of the time-symmetry breaking perturbation. In areas of low reflectivity the rotation angle of TE polarization decreases with increasing incidence angle while the TM polarization increases with increasing incidence angle with the converse occurring in areas of high reflectivity. The formalism and results will be useful in the development of optical and photonic devices based on topological insulators, devices whi...

  5. High reflection mirrors for pulse compression gratings.

    Palmier, S; Neauport, J; Baclet, N; Lavastre, E; Dupuy, G


    We report an experimental investigation of high reflection mirrors used to fabricate gratings for pulse compression application at the wavelength of 1.053microm. Two kinds of mirrors are studied: the mixed Metal MultiLayer Dielectric (MMLD) mirrors which combine a gold metal layer with some e-beam evaporated dielectric bilayers on the top and the standard e-beam evaporated MultiLayer Dielectric (MLD) mirrors. Various samples were manufactured, damage tested at a pulse duration of 500fs. Damage sites were subsequently observed by means of Nomarski microscopy and white light interferometer microscopy. The comparison of the results evidences that if MMLD design can offer damage performances rather similar to MLD design, it also exhibits lower stresses; being thus an optimal mirror substrate for a pulse compression grating operating under vacuum.

  6. Straw combustion on slow-moving grates

    Kær, Søren Knudsen


    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......-column’’ approach and includes the energy equations for both the fuel and the gas accounting for heat transfer between the two phases. The model gives important insight into the combustion process and provides inlet conditions for a computational fluid dynamics analysis of the freeboard. The model predictions...... indicate the existence of two distinct combustion modes. Combustion air temperature and mass flow-rate are the two parameters determining the mode. There is a significant difference in reaction rates (ignition velocity) and temperature levels between the two modes. Model predictions were compared...

  7. Robust topology design of periodic grating surfaces

    Friis, Kasper Storgaard; Sigmund, Ole


    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...

  8. Theoretical and measured performance of diffraction gratings

    Bowler, M.A. E-mail:; Finetti, P.; Holland, D.M.P.; Humphrey, I.; Quinn, F.M.; Roper, M.D


    At the SRS at Daresbury Laboratory, we are undertaking a programme comparing the results from efficiency calculations of diffraction gratings, mainly using the GRADIF code of Neviere, with measured efficiencies. The deviations from the predicted performance are larger for higher orders than for first order. Higher order contamination is important in determining the usability of the beamline for certain types of experiments, particularly at energies below 100 eV.

  9. Theoretical and measured performance of diffraction gratings

    Bowler, M A; Holland, D M P; Humphrey, I; Quinn, F M; Röper, M D


    At the SRS at Daresbury Laboratory, we are undertaking a programme comparing the results from efficiency calculations of diffraction gratings, mainly using the GRADIF code of Neviere, with measured efficiencies. The deviations from the predicted performance are larger for higher orders than for first order. Higher order contamination is important in determining the usability of the beamline for certain types of experiments, particularly at energies below 100 eV.

  10. Detailed Investigations of Load Coefficients on Grates

    Andersen, Thomas Lykke; Rasmussen, Michael R.; Frigaard, Peter

    In this report is presented the results of model tests carried out at Dept. of Civil Engineering, aalborg University (AAU) on behalf of DONG Energy A/S and Vattenfall A/S, Denmark. The objective of the tests was to investigate the load coefficient on different grates and a solid plate for designi...... offshore windmill access platforms against run-up generated forces with special attention to the influence of air entrainment and the angle of attack....

  11. Pain relief is a human right.

    Daher, Michel


    For centuries, medical and surgical treatment has emphasized saving the life of the patient rather than ameliorating the patient's pain, particularly when there were few options for the latter. Today at the dawn of the 21st century, the best available evidence indicates a major gap between an increasingly understanding of the pathophysiology of pain and widespread inadequacy of its treatment. Epidemiologic evidence has proven that chronic pain is a widespread public health issue. Studies of cancer patients' pain control consistently reveal that up to half of patients receive inadequate analgesia and 30% do not receive appropriate drugs for their pain. Equally, for patients suffering HIV/AIDS, 60%-100% will experience pain at some stage in their illness. In the developed world, this gap has prompted a series of declarations and actions by national and international bodies advocating better pain control. One response to the worldwide undertreatment of pain has been to promote the concept that pain relief is a public health issue of such critical importance as to constitute an international imperative and fundamental human right. The importance of pain relief as the core of the medical ethic is clear. Pain clinicians promote the status of pain management beyond that of appropriate clinical practice or even an ethic of good medicine. They advocate a paradigm shift in the medical professions' perspective on pain management, from simply good practice to an imperative founded on patient rights. There is a need to promote policies which create conditions where human beings can bear even incurable illnesses and death in a dignified manner. This must help health professionals or lay groups to initiate a powerful agenda to reform local statutes. The essential components of such legislation are: 1. Reasonable pain management is a right. 2. Doctors have a duty to listen to and reasonably respond to a patient's report of pain. 3. Provision of necessary pain relief is immune from

  12. Grating Spectroscopes and How to Use Them

    Harrison, Ken M


    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,...

  13. Grating Loaded Cantilevers for Displacement Measurements

    Karademir, Ertugrul; Olcum, Selim; Atalar, Abdullah; Aydinli, Atilla


    A cantilever with a grating coupler engraved on its tip is used for measuring displacement. The coupled light in the cantilever is guided to a single mode optical waveguide defined at the base of the cantilever. The grating period is 550 nm and is fabricated on a SOI wafer using nanoimprint lithography. The waveguide and the cantilever are defined by an RIE and cantilevers released by KOH and HF solutions. Light with 1550 nm wavelength, is directed onto the grating coupler and detected at the cleaved end of the SOI waveguide. The angle of incidence is controlled by a motorized rotary stage. Light couples into the waveguide at a characteristic angle with a full width at half maximum of approximately 6.9 mrads translating into a Q factor of 87.5. The displacement sensitivity is measured by driving the cantilever with a frequency controlled piezoelectric element. The modulation of the light at the waveguide output is lock-in detected by a biased infrared detector. The resulting 43%mrad-1 sensitivity can be increased with further optimization.

  14. Grating THz laser with optical pumping

    Khoury, Jed; Haji-saeed, Bahareh; Woods, Charles; Kierstead, John


    In this paper, we present a design for a widely tunable solid-state optically and electrically pumped THz laser based on the Smith-Purcell free-electron laser. In the free-electron laser, an energetic electron beam pumps a metallic grating to generate surface plasmons. Our solid-state optically pumped design consists of a thin layer of dielectic, such as SiNx, sandwiched between a corrugated structure and a thin metal or semiconductor layer. The lower layer is for current streaming, and replaces the electron beam in the original design. The upper layer consists of one micro-grating for coupling the electromagnetic field in, another for coupling out, and a nano-grating for coupling with the current in the lower layer for electromagnetic field generation. The surface plasmon waves generated from the upper layer by an external electromagnetic field, and the lower layer by the applied current, are coupled. Emission enhancement occurs when the plasmonic waves in both layers are resonantly coupled.

  15. Composite cure monitoring with Bragg grating sensors

    Slattery, Kerry T.; Corona-Bittick, Kelli; Dorr, Donald J.


    Residual stress is induced in fiber composite materials during the cure process because the thermal expansion coefficient of the fiber is generally much lower than that of the polymer matrix. The two materials are 'locked' together at the cure temperature. Then, as they cool, the matrix attempts to contract more than the fiber leading to tension in the matrix and compression in the fiber. This can lead to the formation of microcracks parallel to the fibers in thick composite piles or yarns. The magnitude of residual stress can be reduced by modifying the cure cycle; however, optimizing the cure cycle requires a complete understanding of the state of cure throughout the composite. This is a complex problem -- especially in thick composites. Pilot studies have been performed placing Bragg gratin sensors in glass fabric preforms and monitoring the response of the grating during resin infusion and cure. The typical response shows the initial thermal expansion of the Bragg grating, a rapid contraction of the grating as the resin gels, slower contraction during cure, and thermal contraction at the composite thermal expansion coefficient during cool down. This data is then sued with micromechanical models of the fiber/matrix interaction during cure to establish material parameters for cure simulation. Once verified, these cure simulation methods will be used to optimize tooling design and cure cycles in composite components.

  16. Late-Cenozoic relief evolution under evolving climate: a review

    Champagnac, Jean-Daniel; Valla, Pierre; Herman, Fred


    The present review is an attempt to summarize quantitative evidence of Late Cenozoic changes in topographic relief on Earth. We first define different meanings of the word "relief", as it is commonly used, and detail the metrics used to quantify it. We then specify methodological tools used to quantify relief change (primarily lowtemperature thermochronometry and terrestrial cosmogenic nuclides), and analyze published evidence for different regions. Our review first show that relief changes and rates of changes are more important at mid-, than high- or low-latitudes, and appear to be insensitive to mean precipitation rates. We also show that relief change is positive (relief increases) in most of the reported cases (~80%). We subsequently define two functional relationships between relief and erosion, depending on the chosen definition of relief, and propose a conceptual model of landscape memory. We conclude, following others, that erosion rates depends non-linearly on relief evolution, itself being a function of the spatial distribution and rates of erosion. The relief increases documented in this review may be related led to erosion rate increases during the same timescales. Lastly, we discuss the importance of glacial and periglacial processes on Late Cenozoic relief and erosion rate changes, and stress the importance of frost shattering and glacial erosion at mid- and high-latitudes.

  17. Measuring vibration by using fiber Bragg grating and demodulating it by blazed grating

    Xiaojin Guo(郭晓金); Zongmin Yin(殷宗敏); Ning Song(宋宁)


    A method of measuring vibration by using fiber Bragg grating (FBG) and demodulating the spectrum by blazed grating is introduced. The sensor system is made of a simple supported beam with a FBG adhered to its upper surface. A blazed grating is used to demodulate the changing spectrum that is got from the sensor system, and a line charge-coupled device (CCD) is used to accept the diffraction spectrum.Through analyzing the number of the CCD's pixels, we can get the amplitude of vibration and the change of the temperature. The experimental results show that the vibration amplitude of the exciter matches the detected signal under the stable frequency. The temperature shift and vibration signal are also successfully separated.

  18. Towards freeform curved blazed gratings using diamond machining

    Bourgenot, C.; Robertson, D. J.; Stelter, D.; Eikenberry, S.


    Concave blazed gratings greatly simplify the architecture of spectrographs by reducing the number of optical components. The production of these gratings using diamond-machining offers practically no limits in the design of the grating substrate shape, with the possibility of making large sag freeform surfaces unlike the alternative and traditional method of holography and ion etching. In this paper, we report on the technological challenges and progress in the making of these curved blazed gratings using an ultra-high precision 5 axes Moore-Nanotech machine. We describe their implementation in an integral field unit prototype called IGIS (Integrated Grating Imaging Spectrograph) where freeform curved gratings are used as pupil mirrors. The goal is to develop the technologies for the production of the next generation of low-cost, compact, high performance integral field unit spectrometers.

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

    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)


    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.

  20. EPRI PWR Safety and Relief Value Test Program: safety and relief valve test report


    A safety and relief valve test program was conducted by EPRI for a group of participating PWR utilities to respond to the USNRC recommendations documented in NUREG 0578 Section 2.1.2, and as clarified in NUREG 0737 Item II.D.1.A. Seventeen safety and relief valves representative of those utilized in or planned for use in participating domestic PWR's were tested under the full range of selected test conditions. This report contains a listing of the selected test valves and the corresponding as tested test matrices, valve performance data and principal observations for the tested safety and relief valves. The information contained in this report may be used by the participating utilities in developing their response to the above mentioned USNRC recommendations.

  1. Simulation of Novel Tunable Nonlinear Chirped Fiber Bragg Grating

    LIU Yu-min; YU Zhong-yuan; ZHANG Xiao-guang; YU Li; YANG Bo-jun


    A novel tunable chirped fiber Bragg grating technology is proposed and simulated numerically by Matlab. If we adhere a uniform fiber grating with super magnetostrictive film and expose them in a non-uniform magnetic field, the period of the grating can be changed with the strain imposed on it by the magnetostrictive effect .The chirped characteristics can be tuned by changing the magnetic filed which is very flexible in designing.

  2. Adaptive perfectly matched layer for Wood's anomalies in diffraction gratings

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


    We propose an Adaptive Perfectly Matched Layer (APML) to be used in diffraction grating modeling. With a properly tailored co-ordinate stretching depending both on the incident field and on grating parameters, the APML may efficiently absorb diffracted orders near grazing angles (the so-called Wood's anomalies). The new design is implemented in a finite element method (FEM) scheme and applied on a numerical example of a dielectric slit grating. Its performances are compared with classical PML with constant stretching coefficient.

  3. Refractometric sensors based on long period optical fiber gratings


    In this work, results of the design of uniform and nonuniform longperiod gratings are presented, with a view to being used as refractometric sensors. We found an optimal combination of the longitudinal variation of the fiber refractive index and the grating period, which increases the sensor linearity in comparison with a uniform grating, without decreasing its average sensitivity within a range of the external refractive index from 1.41 to 1.44.

  4. Optical implementation of the Hopfield neural network with matrix gratings

    Yeh, Sheng L.; Lo, Rong C.; Shi, Cha Y.


    We propose a new method for the optical implementation of the Hopfield neural network with a universal tool. The tool is a matrix grating constituted with a group of element gratings. The algorithms for designing a matrix grating are proposed, and a matrix grating is created to execute recognition experiments by use of the Hopfield neural network. The experimental results demonstrate that the proposed method performs well. The stability of the light efficiencies of different optical components used in optical networks is also considered.

  5. Effect of Effective Refractive Index of Grating in FBG Splitter



    Full Text Available The Fiber Bragg Gratings have been used extensively in the communication industry. Fiber Bragg grating is written directly into the core of the optical fiber and it is quite an attractive technique for wavelength splitter since it provides high reflectivity at a certain wavelength, with negligible transmission losses for others, providing a wavelength-channel selection with low crosstalk between adjacent channels.In this paper we propose a Fiber Bragg Grating base splitter with alteration of effective refractive index of grating for Ethernet passive optical network. With the increase in the effective refractive index the reflectivity of grating is increased. We analysed the effect of effective refractive index on reflectivity of grating. In our work the Bragg wavelength has been fixed at 1550 nm,length of the grating as 10mm and with effective refractive index as 4.0 it has been found that the reflectivity of the grating or the effectiveness of the grating in extracting the wavelength is 92-93%.

  6. Modeling spatially localized photonic nanojets from phase diffraction gratings

    Geints, Yu. E., E-mail: [V.E. Zuev Institute of Atmospheric Optics SB RAS (IAO SB RAS), 1, Academician Zuev Square, Tomsk 634055 (Russian Federation); Tomsk State University, 36, Lenina Avenue, Tomsk 634050 (Russian Federation); Zemlyanov, A. A. [V.E. Zuev Institute of Atmospheric Optics SB RAS (IAO SB RAS), 1, Academician Zuev Square, Tomsk 634055 (Russian Federation)


    We investigated numerically the specific spatially localized intense optical structure, a photonic nanojet (PNJ), formed in the near-field scattering of optical radiation at phase diffraction gratings. The finite-difference time-domain technique was employed to study the PNJ key parameters (length, width, focal distance, and intensity) produced by diffraction gratings with the saw-tooth, rectangle, and hemispheric line profiles. Our analysis showed that each type of diffraction gratings produces a photonic jet with unique characteristics. Based on the numerical calculations, we demonstrate that the PNJ could be manipulated in a wide range through the variation of period, duty cycle, and shape of diffraction grating rulings.

  7. Diffraction Gratings for High-Intensity Laser Applications

    Britten, J


    The scattering of light into wavelength-dependent discrete directions (orders) by a device exhibiting a periodic modulation of a physical attribute on a spatial scale similar to the wavelength of light has been the subject of study for over 200 years. Such a device is called a diffraction grating. Practical applications of diffraction gratings, mainly for spectroscopy, have been around for over 100 years. The importance of diffraction gratings in spectroscopy for the measurement of myriad properties of matter can hardly be overestimated. Since the advent of coherent light sources (lasers) in the 1960's, applications of diffraction gratings in spectroscopy have further exploded. Lasers have opened a vast application space for gratings, and apace, gratings have enabled entirely new classes of laser systems. Excellent reviews of the history, fundamental properties, applications and manufacturing techniques of diffraction gratings up to the time of their publication can be found in the books by Hutley (1) and more recently Loewen and Popov (2). The limited scope of this chapter can hardly do justice to such a comprehensive subject, so the focus here will be narrowly limited to characteristics required for gratings suitable for high-power laser applications, and methods to fabricate them. A particular area of emphasis will be on maximally-efficient large-aperture gratings for short-pulse laser generation.

  8. Improved layer peeling algorithm for strongly reflecting fiber gratings

    Liqun Huang; Weiping Huang; Jinkuan Wang; Guang Yang


    @@ An improved algorithm based on the layer peeling (LP) method is proposed and demonstrated.The new method is shown to be effective for mitigating the impact of numerical errors on reconstruction of coupling function for strongly reflecting Bragg gratings.As examples,a flat-top dispersion-free fiber grating and a fiber-grating dispersion compensator are designed by the improved LP method.For a chirp grating,more accurate results are demonstrated in comparison with those obtained by the integral layer peeling (ILP) method.

  9. Wavelength-conserving grating router for intermediate wavelength density

    Deri, Robert J.; Patel, Rajesh R.; Bond, Steven W.; Bennett, Cory V.


    A wavelength router to be used for fiber optical networking router is based on a diffraction grating which utilizes only N wavelengths to interconnect N inputs to N outputs. The basic approach is to augment the grating with additional couplers or wavelength selective elements so than N-1 of the 2N-1 outputs are combined with other N outputs (leaving only N outputs). One embodiment uses directional couplers as combiners. Another embodiment uses wavelength-selective couplers. Another embodiment uses a pair of diffraction gratings to maintain parallel propagation of all optical beams. Also, beam combining can be implemented either by using retroflection back through the grating pair or by using couplers.

  10. Bragg Fibers with Soliton-like Grating Profiles

    Bugaychuk S.


    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.

  11. Perambatan Gelombang Optik pada Grating Sinusoidal dengan Chirp dan Taper

    Isnani Darti


    menggunakan MIL, dipelajari perubahan respon optik pada grating sinusoidal akibat variasi amplitudo modulasi indeks (taper dan variasi frekuensi spasial grating (chirp. Hasil simulasi menunjukkan bahwa taper menyebabkan adanya fenomena penghilangan side-lobe pada spektrum transmitansi. Adanya chirp menyebabkan penghalusan side-lobe pada spektrum transmitansi dengan semakin besar parameter chirp menyebabkan peningkatan transmitansi di sekitar pusat band-gap dari grating homogen. Selain implementasi integrasi numerik (Runge-Kutta, MIL merupakan metode eksak sehingga dapat digunakan untuk mengevaluasi validitas metode yang sering digunakan yaitu Persamaan Moda Tergandeng (PMT. Dari hasil perbandingan dapat disimpulkan bahwa secara umum PMT kurang akurat dalam menganalisis struktur grating sinusoidal baik homogen maupun tak-homogen.

  12. Higher Order Diffraction Characteristics of Fiber Bragg Grating

    Sunita P. Ugale


    Full Text Available The effect of grating saturation on higher order diffraction characteristic of FBG is investigated by using Coupled mode theory. Grating saturation effects were considered in the index distribution model showing the significant influence on the coupling process and hence on the reflectivity characteristics of FBG. Maximum reflectivity curves for first and higher order diffraction of FBG are plotted for different values of saturation coefficient. The effect of change in length and change in refractive index are studied. The behavior of grating for higher order of diffraction is totally different than first order of diffraction. In saturated gratings, the higher order diffraction can be utilized for multiparameter sensing

  13. Modeling Component-based Bragg gratings Application: tunable lasers

    Hedara Rachida


    Full Text Available The principal function of a grating Bragg is filtering, which can be used in optical fibers based component and active or passive semi conductors based component, as well as telecommunication systems. Their ideal use is with lasers with fiber, amplifiers with fiber or Laser diodes. In this work, we are going to show the principal results obtained during the analysis of various types of grating Bragg by the method of the coupled modes. We then present the operation of DBR are tunable. The use of Bragg gratings in a laser provides single-mode sources, agile wavelength. The use of sampled grating increases the tuning range.

  14. Spherical grating based x-ray Talbot interferometry

    Cong, Wenxiang, E-mail:, E-mail:, E-mail:; Xi, Yan, E-mail:, E-mail:, E-mail:; Wang, Ge, E-mail:, E-mail:, E-mail: [Biomedical Imaging Center, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)


    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

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

    Heine, C.


    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.

  16. Holographic Grating Formation in Cationic Photopolymers with Dark Reaction

    WEI Hao-Yun; CAO Liang-Cai; GU Claire; XU Zhen-Feng; HE Ming-Zhao; HE Qing-Sheng; HE Shu-Rong; JIN Guo-Fan


    @@ We propose a new formula to describe the dynamics of holographic grating formation under low intensity pulse exposures in cationic photopolymers, in which the dark reaction contributes dominantly to the grating strength.The formula is based on the living polymerization mechanism and the diffusion-free approximation. The analytical solution indicates that the grating formation time depends on the termination rate constant, while the final grating strength depends linearly on the total exposure energy. These theoretical predictions are verified experimentally using the Aprilis HMC-400μm photopolymer. The results can provide guidelines for the control and optimization of the holographic recording conditions in practical applications.

  17. Technology and information sharing in disaster relief

    Bjerge, Benedikte; Clark, Nathan; Fisker, Peter;


    This paper seeks to examine the extent to which technological advances can enhance inter-organizational information sharing in disaster relief. Our case is the Virtual OSOCC (On-Site Operations Coordination Centre) which is a part of the Global Disaster Alert and Coordination System (GDACS) under...... database of user interaction including more than 20,000 users and 11,000 comments spread across approximately 300 disaster events. Controlling for types and severities of the events, location-specific vulnerabilities, and the overall trends, we find that the introduction of new features have led...

  18. EC Hidraulic Drive Cylinder Relief Vlave Test

    Wu, J.; /Fermilab


    This engineering note documents the testing of the set pressure of the EC hydraulic drive cylinder relief valve. The purpose of the relief valve is to provide a safety measure in the event that oil becomes trapped in the rod side of the cylinder and pressure is applied to the cap side. The note includes an explanation of the procedure used and a summary of the result of the testing done on February 14, 1991 by Gary Trotter. The result was that the cylinder relief valve relieved at the correct set pressure of 10,500 psig. The basic concern is for the protection of the cylinder. The pump is capable of providing up to 10,500 psi of pressure to either side of the cylinder. The cylinder is rated for 10,500 psi. Under normal operating conditions, the valves would be open, and the pumping pressure would automatically flow oil into one side, and remove oil from the other side. If, however, the valve for the other side was closed, so that oil could not be removed, then the pressure would build in that side. If the rod side is pressurized to the maximum pump pressure of 10,500 psi, the cross sectional area ratio of 2.29 results in a pressure of approximately 4600 psi in the cap side, which is well under the rated pressure. If, however, the cap side is pressurized to 10,500 psi, the cross sectional area would produce a pressure of approximately 24,000 psi in the rod side, which could damage the cylinder. Therefore, the pressure on the rod side must be limited to the rated pressure of 10,500 psi. In reality, the maximum operating force on the piston would be under 11,000 Ibs., which would result in the maximum cylinder pressure being under 8000 psi to the rod side, and under 3500 psi to the cap side. Therefore, the relief is only needed as a safety precaution in the case that oil becomes trapped.

  19. LOFT pressurizer safety: relief valve reliability

    Brown, E.S.


    The LOFT pressurizer self-actuating safety-relief valves are constructed to the present state-of-the-art and should have reliability equivalent to the valves in use on PWR plants in the U.S. There have been no NRC incident reports on valve failures to lift that would challenge the Technical Specification Safety Limit. Fourteen valves have been reported as lifting a few percentage points outside the +-1% Tech. Spec. surveillance tolerance (9 valves tested over and 5 valves tested under specification). There have been no incident reports on failures to reseat. The LOFT surveillance program for assuring reliability is equivalent to nuclear industry practice.

  20. Holistic relief of pain - Nursing approach

    Evaggelos Giavasopoulos


    Full Text Available It is well known that the patients who suffer from pain can develop a wide variety of behaviours. At the same time they experience a plethora of biological, psychological and social problems. Undeniably the nurses constitute an integral part of the multidisciplinary team of approach and relief of patient’s pain. The nurse’s role is developed and organized with independence in the health care team and expresses itself in a wide spectrum of activities. Aim in the present article is to highlight the force of nurse among the multidisciplinary team, analyzing the multiple roles undertaken by nurses, as well as the necessity for holistic approach of pain.

  1. CAS scientists active in earthquake relief operation


    @@ Soon after the devastating earthquake taking place on last 12 May in Sichuan, the CAS leadership promptly mobilized its researchers to dedicate their expertise to the nationwide drive of the disaster's relief and reduction. A leading group was established to coordinate the Academy's efforts in this regard. All of the eight CAS institutions located in Sichuan were organized to do everything possible to reduce their losses to the minimum. At the same time, a trans-departmental and interdisciplinary taskforce was formed to provide a powerful S&T backing for the nationwide drive.

  2. Holographic Recording and Applications of Multiplexed Volume Bragg Gratings in Photo-Thermo-Refractive Glass


    applications of multiplexed volume bragg gratings in photo- thermo -refractive glass Volume Bragg grating (VBG) structures are capable of diffracting...research in the holographic recording of volume Bragg gratings in photo- thermo -refractive (PTR) glass has shown that these gratings are extremely...ABSTRACT Holographic recording and applications of multiplexed volume bragg gratings in photo- thermo -refractive glass Report Title Volume Bragg grating (VBG

  3. Low-Dispersion Fibre Bragg Gratings Written Using the Polarization Control Method

    Deyerl, Hans Jürgen; Plougmann, Nikolai; Jensen, Jesper Bo Damm;


    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....

  4. Insights into Casual Relief Teaching: Casual Relief Teachers' Perceptions of Their Knowledge and Skills

    Nicholas, Maria; Wells, Muriel


    Research into the experiences of casual relief teachers (CRTs) (substitute or supply teachers) across Australia and internationally has reported feelings of marginalisation among participants. These findings are concerning when one considers that students might be in the care of CRTs for an equivalent of 1 year or more throughout their schooling.…

  5. An explanation for the non-uniform grating effects during recording of diffraction gratings in photopolymers.

    Blaya, S; Acebal, P; Carretero, L; Murciano, A; Madrigal, R F; Fimia, A


    The recent results reported in reference 1 have produced an increased interest in explaining deviations from the ideal behavior of the energetic variation of the diffraction efficiency of holographic gratings. This ideal behavior occurs when uniform gratings are recorded, and the index modulation is proportional to the energetic exposure. As a result, a typical sin(2) curve is obtained reaching a maximum diffraction efficiency and saturation at or below this value. However, linear deviations are experimentally observed when the first maximum on the curve is lower than the second. This effect does not correspond to overmodulation and recently in PVA/acrylamide photopolymers of high thickness it has been explained by the dye concentration in the layer and the resulting molecular weight of the polymer chains generated in the polymerization process. In this work, new insights into these deviations are gained from the analysis of the non-uniform gratings recorded. Therefore, we show that deviations from the linear response can be explained by taking into account the energetic evolution of the index modulation as well as the fringe bending in the grating.

  6. The glacial relief in the Leaota Mountains



    Full Text Available The presence of glacial relief in the Romanian medium height massifs is still controversial. The medium height mountains, such as theLeaota Mountains (in the Bucegi group, with maximum altitudes of almost 2000 m andmedium altitudes of approximately 1250 m, can display traces of glacial relief dating from theUpper Pleistocene. The aim of this article is to provide evidence about the presence of theglacial morphology in the northern part of the Leaota Peak, the main orographic node in themassif with the same name. Thus, on the basis of field observations, of topographical mapanalysis and by using the geographic information systems which made possible a detailedmorphometric analysis, I was able to gather evidence proving the existence of a glacial cirquein the Leaota Mountains. The arguments put forward in this article show that the glacial reliefis represented in the Leaota Mountains through a small-size suspended glacial cirque, whichdisplays all the morphologic elements proving the existence of glaciation in this massif.

  7. Increasing the Useful Life of Quench Reliefs with Inconel Bellows

    Soyars, W. M. [Fermilab


    Reliable quench relief valves are an important part of superconducting magnet systems. Fermilab developed bellows-actuated cryogenic quench reliefs which have been in use since the early l 980's. The original design uses a stainless steel bellows. A high frequency, low amplitude vibration during relieving events has resulted in fatigue failures in the original design. To take advantage of the improved resistance to fatigue of Inconel, a nickel-chromium alloy, reliefs using Inconel 625 bellows were made. Design, development, and testing of the new version reliefs will be discussed. Tests show that relief valve lifetimes using Inconel bellows are more than five times greater than when using the original stainless steel bellows. Inconel bellows show great promise in increasing the lifetime of quench relief valves, and thus the reliability of accelerator cryogenic systems.

  8. Gratings in passive and active optical waveguides

    Berendt, Martin Ole


    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...... investigated. Pump induced temperature gratdient in the DFB structure has been found to degrade the output power. Selective cooling to compensate the temperature gradient more than doubled the output power. The experiment indicates that ouput power in excess of 10mW, with 80 mW of 980 nm pumping is feasible...

  9. Longitudinal coupling effect in microfiber Bragg gratings

    Zhao, Ping; Zhang, Jihua; Wang, Guanghui; Jiang, Meng; Ping Shum, Perry; Zhang, Xinliang


    We theoretically present longitudinal coupling effect (LCE) in air-cladding microfiber Bragg gratings (MFBGs). Distinct from conventional weakly-guiding optical fibers, large longitudinal electric field (Ez) exists in wavelength-scale microfibers. Due to LCE, MFBG reflectivity can be reduced by more than 30% within the band-gap and the full width at half maximum (FWHM) is obviously narrowed. This theoretical analytical work is instructive to precisely design and fabricate MFBGs that are promising in the areas of optical sensing and nanophotonics.

  10. Fractal signatures in the aperiodic Fibonacci grating.

    Verma, Rupesh; Banerjee, Varsha; Senthilkumaran, Paramasivam


    The Fibonacci grating (FbG) is an archetypal example of aperiodicity and self-similarity. While aperiodicity distinguishes it from a fractal, self-similarity identifies it with a fractal. Our paper investigates the outcome of these complementary features on the FbG diffraction profile (FbGDP). We find that the FbGDP has unique characteristics (e.g., no reduction in intensity with increasing generations), in addition to fractal signatures (e.g., a non-integer fractal dimension). These make the Fibonacci architecture potentially useful in image forming devices and other emerging technologies.

  11. Computer simulation of multiple dynamic photorefractive gratings

    Buchhave, Preben


    The benefits of a direct visualization of space-charge grating buildup are described. The visualization is carried out by a simple repetitive computer program, which simulates the basic processes in the band-transport model and displays the result graphically or in the form of numerical data. The....... The simulation sheds light on issues that are not amenable to analytical solutions, such as the spectral content of the wave forms, cross talk in three-beam interaction, and the range of applications of the band-transport model. (C) 1998 Optical Society of America....

  12. 46 CFR 64.71 - Marking of pressure relief devices.


    ... AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.71 Marking...— (a) Set pressure rating; (b) Rated flow capacity expressed as cubic feet of standard air (60 °F 14.7... 46 Shipping 2 2010-10-01 2010-10-01 false Marking of pressure relief devices. 64.71 Section 64.71...

  13. Sandy PMO Disaster Relief Appropriations Act of 2013 Financial Data

    Department of Homeland Security — Sandy PMO: Disaster Relief Appropriations Act of 2013 (Sandy Supplemental Bill) Financial Data. This is the Sandy Supplemental Quarterly Financial Datasets that are...


    X.C.Zhao; Y.D.Zhang; H.W.Zhang; Q.Wu


    A finite element model is developed for the simulation of vibration stress relief (VSR) after welding.For the nonresonant vibration,the reduction in stress strongly depends on the amplitude of vibration.For the resonant vibration,the vibration frequency is the key for stress relief.The vibration frequency should be close to the structure natural frequency for the desired vibration mode.Only small vibration amplitude is required,which will be amplified during vibration.Vibration time does not have a major impact on vibration stress relief.When the amplitude of vibration stress relief is large,the treatment will be more effective.

  15. Study of safety relief valve operation under ATWS conditions. [PWR

    Hutmacher, E.S.; Nesmith, B.J.; Brukiewa, J.B.


    A literature survey and analysis project has been performed to determine if recent (since mid-1975) data has been reported which could influence the current approach to predicting PWR relief valve capacity under ATWS conditions. This study was conducted by the Energy Technology Engineering Center for NRC. Results indicate that the current relief valve capacity model tends to predict less capacity than actually obtains; however, no experimental verification at PWR ATWS conditions was found. Other project objectives were to establish the availability of methods for evaluating reaction forces and back pressure effects on relief valve capacity, and to determine if facilities exist which are capable of testing PWR relief valves at ATWS conditions.

  16. High-refractive-index measurement with an elastomeric grating coupler

    Kocabas, Askin; Ay, Feridun; Dana, Aykutiu; Kiyat, Isa; Aydinli, Atilla


    An elastomeric grating coupler fabricated by the replica molding technique is used to measure the modal indices of a silicon-on-insulator (SOI) planar waveguide structure. Because of the van der Waals interaction between the grating mold and the waveguide, the elastomeric stamp makes conformal conta

  17. Cryogenic VPH gratings for the CELT/TMT

    Blais-Ouellette, Sebastien; Guzman, Dani; Elgamil, Amal; Rallison, Richard


    Characterization of Volume Phase Holographic gratings at cryogenic temperatures have been conducted using a new test facility at Caltech. The new test bench includes a cryostat that allows large angles for incident and diffracted light. Gratings under tests are shielded from thermal background, and precisely and uniformly temperature controlled. Preliminary results are presented and show little temperature dependence of the efficiency function.

  18. Linear Fresnel Spectrometer Chip with Gradient Line Grating

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


    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.

  19. Analysis of the optical parameters of phase holographic gratings

    Є.О. Тихонов


    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.

  20. Pre-correction of projected gratings for surface profile measurement

    Sun, Cuiru; Lu, Hua


    This paper discusses errors caused by unequal grating pitch in applying the phase-shifted digital grating projection method for object profile measurement. To address the related issues, a new scheme is proposed to effectively improve the uniformity of the projected grating pitch across the object surface with no additional hardware cost. The improvement is mainly realized via a grating pitch pre-correction algorithm assisted by Digital Speckle/Image Correlation (DSC/DIC). DIC is utilized to accurately determine the surface grating pitch variation when an originally equal-pitched grating pattern is slant projected to the surface. With the actual pitch distribution function determined, a pre-corrected grating with unequal pitch is generated and projected, and the iterative algorithm reaches a constant pitched surface grating. The mapping relationship between the object surface profile (or out-of-plane displacement) and the fringe phase changes is obtained with a real-time subtraction based calibration. A quality guide phase unwrapping method is also adopted in the fringe processing. Finally, a virtual reference phase plane obtained by a 3-point plane fitting algorithm is subtracted to eliminate the carrier phase. The study shows that a simple optical system implemented with the mentioned improvements remarkably increase the accuracy and the efficiency of the measurement.

  1. Birefringent Bragg Gratings in Highly-Nonlinear Photonic Crystal Fiber

    Kevin Cook; John Canning; John Holdsworth


    Efficient writing of Bragg gratings in 12-ring highly-nonlinear photonic crystal fibers is described. Experimental and numerical investigations are performed to reveal the optimum angle for coupling UV writing light to the core. Furthermore, we show that the formation of a strongly briefringent grating is at a particular angle of orientation.

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

    Chen, Yu-Yuan; Liu, Zhuan-Zhuan; Wan, Ren-Gang, E-mail:


    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.

  3. 75 FR 41889 - Certain Steel Grating From China


    ... Register on February 25, 2010 (75 FR 8746). The hearing was held in Washington, DC, on May 25, 2010, and... 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...

  4. Transmission gratings for beam sampling and beam splitting.

    Popov, E K; Loewen, E G; Neviére, M


    Transmission gratings have rarely been used for beam sampling because they require special properties from dielectric overcoatings, which, to the best of our knowledge, are described here for the first time. Although such gratings are often used as beam splitters, their nature can be modified along the same principles with thin metal coatings, which are described.

  5. Holographic gratings in photorefractive polymers without external electric field

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


    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...

  6. Compact Bragg Gratings for Long-Range Surface Plasmon Polaritons

    Boltasseva, Alexandra; Bozhevolnyi, Sergey I; Nikolajsen, Thomas


    lengths (from 20 to 160 mm), heights (tens of nm) and widths of the metal ridges forming the grating, and demonstrate the reflectivity of up to 60% and bandwidths ranging from 5 to 40 nm. By using a simple lossless-uniform-grating description, we estimate the effective refractive index modulation in LR...

  7. Wavelength-independent field enhancement in subwavelength gratings

    Ivinskaya, Aliaksandra; Novitsky, Andrey; Shyroki, D.


    We show that lamellar metal gratings exhibit total transmission of incident radiation and strong nonresonant electric field enhancement in extremely subwavelength regime (in the nanometer-sized slits). With high accuracy the enhancement equals the ratio of the grating period to the slit width...

  8. Synthesis of Planar Reflective Gratings for Silicon Interconnects

    Serge Bidnyk


    Full Text Available The design and simulations of planar reflective gratings for building optical interconnects in silicon-on-insulator (SOI were studied for a range of silicon core thicknesses of 0.1 to 10 μm. The verticality of the grating facets has been shown to be the main contributing factor to the cumulative crosstalk in thick silicon cores. The dispersion property of the slab was found to limit the minimal thickness of the core for polarization-insensitive gratings. The effects of polarization-dependent confinement on optical crosstalk were studied. The findings were used to design and simulate a polarization-insensitive 18-channel coarse wavelength division demultiplexer (CWDM with a free spectral range of over 600 nm. The CWDM demultiplexer uses a 1.7 μm silicon core and combines a shallow-etch tapered rib structure and multimode silicon channels to produce box-like passbands for integrated receiver applications. The diffraction grating was constructed using double astigmatic point design with phase-corrected grating facets to reduce astigmatism. Optical properties of the planar gratings have been simulated using quasivectorial diffraction grating theory. The simulation results confirm that there is high diffraction efficiency and low optical crosstalk over the entire range of operation. Applications of planar silicon gratings to the synthesis of silicon interconnects are discussed.

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

    Sirenko, Yuriy K


    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...

  10. Light scanner based on a viscoelastic stretchable grating.

    Simonov, A N; Akhzar-Mehr, O; Vdovin, G


    We present a new technique for light scanning by use of viscoelastic-based deformable phase diffraction gratings. Mechanical stretching of the grating permits control of its spatial period, and thus the orders of diffraction can be spatially deflected. In the experiments the viscoelastic gratings with triangular and rectangular profiles have been characterized at lambda = 633 nm. It is demonstrated that the reversible elongation can exceed 20% of the initial length. For the triangular profile grating, the diffraction angle of the first order changed from 6.6 degrees to 5.4 degrees while the diffraction efficiency remained almost constant at approximately 17%. Dynamic scanning of a laser beam at frequencies of approximately 1 kHz is demonstrated by use of electromechanically driven viscoelastic gratings.

  11. Light scanner based on a viscoelastic stretchable grating

    Simonov, A. N.; Akhzar-Mehr, O.; Vdovin, G.


    We present a new technique for light scanning by use of viscoelastic-based deformable phase diffraction gratings. Mechanical stretching of the grating permits control of its spatial period, and thus the orders of diffraction can be spatially deflected. In the experiments the viscoelastic gratings with triangular and rectangular profiles have been characterized at lambda = 633 nm. It is demonstrated that the reversible elongation can exceed 20% of the initial length. For the triangular profile grating, the diffraction angle of the first order changed from 6.6μ to 5.4μ while the diffraction efficiency remained almost constant at ~17%. Dynamic scanning of a laser beam at frequencies of ~1 kHz is demonstrated by use of electromechanically driven viscoelastic gratings.

  12. Specification of multiple image characteristics viewed through a grating

    Abolhassani, Mohammad


    When a person observes an object, illuminated incoherently by a quasi-monochromatic source, through a grating, he will see more than one image. Angular positions of these images are derived in terms of wavelength, period of the grating, separation between the object and the grating, and position of the object relative to the observer. In a special case, when the object is another grating, the condition of coincidence of its multiple images is investigated. The relation derived is, to some extent, similar to that seen in the Lau effect. As a secondary outcome, it is shown that the sum of the squared modulus of the odd Fourier series coefficients for a binary grating function is equal to that of the even coefficients.

  13. Excitation of a surface plasmon with an elastomeric grating

    Kocabas, A.; Dâna, A.; Aydinli, A.


    We report on a new method to excite surface plasmon polaritons on a thin metal slab surface using an elastomeric grating which is fabricated by replica molding technique. The grating is placed on the metal surface which creates a periodic perturbation on the surface matching the momentum of the incident light to that of the surface plasmon. The conformal contact between the metal surface and the elastomeric grating changes the dielectric medium periodically and allows the observation of an effective surface plasmon polariton at the metal-air and metal-polymer interfaces of the grating. To clarify the nature of the observed plasmon, comparison of the elastomeric grating with elastomeric slabs was performed with the attenuated total reflection method.

  14. Flat acoustic lens by acoustic grating with curled slits

    Peng, Pai; Xiao, Bingmu; Wu, Ying, E-mail:


    We design a flat sub-wavelength lens that can focus acoustic wave. We analytically study the transmission through an acoustic grating with curled slits, which can serve as a material with tunable impedance and refractive index for acoustic waves. The effective parameters rely on the geometry of the slits and are independent of frequency. A flat acoustic focusing lens by such acoustic grating with gradient effective refractive index is designed. The focusing effect is clearly observed in simulations and well predicted by the theory. We demonstrate that despite the large impedance mismatch between the acoustic lens and the matrix, the intensity at the focal point is still high due to Fabry–Perot resonance. - Highlights: • Expression of transmission coefficient of an acoustic grating with curled slits. • Non-dispersive and tunable effective medium parameters for the acoustic grating. • A flat acoustic focusing lens with gradient index by using the acoustic grating.

  15. Asymmetric dynamic phase holographic grating in nematic liquid crystal

    Ren, Chang-Yu; Shi, Hong-Xin; Ai, Yan-Bao; Yin, Xiang-Bao; Wang, Feng; Ding, Hong-Wei


    A new scheme for recording a dynamic phase grating with an asymmetric profile in C60-doped homeotropically aligned nematic liquid crystal (NLC) was presented. An oblique incidence beam was used to record the thin asymmetric dynamic phase holographic grating. The diffraction efficiency we achieved is more than 40%, exceeding the theoretical limit for symmetric profile gratings. Both facts can be explained by assuming that a grating with an asymmetric saw-tooth profile is formed in the NLC. Finally, physical mechanism and mathematical model for characterizing the asymmetric phase holographic grating were presented, based on the photo-refractive-like (PR-like) effect. Project supported by the Science and Technology Programs of the Educational Committee of Heilongjiang Province, China (Grant No. 12541730) and the National Natural Science Foundation of China (Grant No. 61405057).

  16. Self Referencing Heterodyne Transient Grating Spectroscopy with Short Wavelength

    Jakob Grilj


    Full Text Available Heterodyning by a phase stable reference electric field is a well known technique to amplify weak nonlinear signals. For short wavelength, the generation of a reference field in front of the sample is challenging because of a lack of suitable beamsplitters. Here, we use a permanent grating which matches the line spacing of the transient grating for the creation of a phase stable reference field. The relative phase among the two can be changed by a relative translation of the permanent and transient gratings in direction orthogonal to the grating lines. We demonstrate the technique for a transient grating on a VO2 thin film and observe constructive as well as destructive interference signals.

  17. Electro-optically tunable diffraction grating with photoaligned liquid crystals

    Węgłowski, Rafał; Kozanecka-Szmigiel, Anna; Piecek, Wiktor; Konieczkowska, Jolanta; Schab-Balcerzak, Ewa


    This work shows the possibility of fabricating one- and two-dimensional diffraction structures based on liquid crystals photoaligned with the layers of photosensitive azobenzene poly(ester imide). The gratings involve a micron-sized planar-twisted nematic alignment. The diffraction efficiency of these gratings is controlled by a uniform electric field applied across the cell. The electro-optical measurements showed short switching times (0.8 ms and 7 ms for τrise and τdecay respectively) and low driving electric fields (1 . 5 V / μm) of 1st order diffracted light. The LC grating is regarded as an amplitude grating in the low electric field region and a phase grating in the high electric field region. Moreover the diffraction efficiency is polarization-independent in the wide range of external electric fields.

  18. Electromagnetically Induced Grating Without Absorption Using Incoherent Pump

    Chen, Yu-Yuan; Liu, Zhuan-Zhuan; Wan, Ren-Gang


    We propose a scheme for creating electromagnetically induced grating in a four-level double- Λ atomic system driven by a coupling field and an incoherent pump field. Owing to the incoherent pumping process, large refractivity accompanied with vanishing absorption or even gain across the probe field can be built up in the atoms, thus phase grating or gain-phase grating, which diffracts a probe light into different directions, can be formed with the help of a standing-wave coupling field. The diffraction efficiency of the gratings can be tuned by the coupling field intensity and the incoherent pump rate, hence the proposed gratings should be suitable for beam splitter and optical switching in optical communication and networking.

  19. Anchoring properties of substrate with a grating surface

    Ye Wen-Jiang; Xing Hong-Yu; Yang Guo-Chen


    The anchoring properties of substrate with a grating surface are investigated analytically. The alignment of nematic liquid crystal (NLC) in a grating surface originates from two mechanisms, thus the anchoring energy consists of two parts. One originates from the interaction potential between NLC molecules and the molecules on the substrate surface,and the other stems from the increased elastic strain energy. Based on the two mechanisms, the expression of anchoring energy per unit area of a projected plane of this grating surface is deduced and called the equivalent anchoring energy formula. Both the strength and the easy direction of equivalent anchoring energy are a function of the geometrical parameters (amplitude and pitch) of a grating surface. By using this formula, the grating surface can be replaced by its projected plane and its anchoring properties can be described by the equivalent anchoring energy formula.

  20. Analytical Alignment Tolerances for Off-Plane Reflection Grating Spectroscopy

    Allured, Ryan


    Future NASA X-ray Observatories will shed light on a variety of high-energy astrophysical phenomena. Off-plane reflection gratings can be used to provide high throughput and spectral resolution in the 0.3--1.5 keV band, allowing for unprecedented diagnostics of energetic astrophysical processes. A grating spectrometer consists of multiple aligned gratings intersecting the converging beam of a Wolter-I telescope. Each grating will be aligned such that the diffracted spectra overlap at the focal plane. Misalignments will degrade both spectral resolution and effective area. In this paper we present an analytical formulation of alignment tolerances that define grating orientations in all six degrees of freedom. We verify our analytical results with raytrace simulations to fully explore the alignment parameter space. We also investigate the effect of misalignments on diffraction efficiency.

  1. Groove shape characteristics of echelle gratings with high diffraction efficiency

    Zhang, Shanwen; Mi, Xiaotao; Zhang, Qian; Jirigalantu; Feng, Shulong; Yu, Haili; Qi, Xiangdong


    The groove shape characteristics of echelle gratings with high diffraction efficiency are investigated. Using the coordinate transformation method (C method), an r-2 aluminum echelle with 79 grooves/mm is optimized through rigorous numerical simulations and shows high diffraction efficiency of 76-81% in the high Littrow orders. A grating is found to be essentially an echelle if it contains a series of reflective facets with a specific tilt angle that are located far from the nonworking facet of the grating and have a deep groove depth; any groove shape that meets these conditions can be called an echelle grating. The underlying mechanism is analyzed phenomenologically using electromagnetic theory. The universal model proposed here, which represents a new cognitive understanding of the concept of the echelle, is ready for use in manufacturing applications and offers a new perspective for the fabrication of these gratings.

  2. Plasmonic band gap cavities on biharmonic gratings

    Kocabas, Askin; Seckin Senlik, S.; Aydinli, Atilla


    In this paper, we have experimentally demonstrated the formation of plasmonic band gap cavities in infrared and visible wavelength range. The cavity structure is based on a biharmonic metallic grating with selective high dielectric loading. A uniform metallic grating structure enables strong surface plasmon polariton (SPP) excitation and a superimposed second harmonic component forms a band gap for the propagating SPPs. We show that a high dielectric superstructure can dramatically perturb the optical properties of SPPs and enables the control of the plasmonic band gap structure. Selective patterning of the high index superstructure results in an index contrast in and outside the patterned region that forms a cavity. This allows us to excite the SPPs that localize inside the cavity at specific wavelengths, satisfying the cavity resonance condition. Experimentally, we observe the formation of a localized state in the band gap and measure the dispersion diagram. Quality factors as high as 37 have been observed in the infrared wavelength. The simplicity of the fabrication and the method of testing make this approach attractive for applications requiring localization of propagating SPPs.

  3. Study on talbot pattern for grating interferometer

    Kim, Young Ju; Oh, Oh Sung; Lee, Seung Wook [Dept. of School of Mechanical Engineering, Pusan National University, Busan (Korea, Republic of); Kim, Jong Yul [Neutron Instrument Division, Korea Atomic Energy Reserch Institute, Daejeon (Korea, Republic of)


    One of properties which X-ray and Neutron can be applied nondestructive test is penetration into the object with interaction leads to decrease in intensity. X-ray interaction with the matter caused by electrons, Neutron caused by atoms. They share applications in nondestructive test area because of their similarities of interaction mechanism. Grating interferometer is the one of applications produces phase contrast image and dark field image. It is defined by Talbot interferometer and Talbot-Lau interferometer according to Talbot effect and Talbot-Lau effect respectively. Talbot interferometer works with coherence beam like X-ray, and Talbot-Lau has an effect with incoherence beam like Neutron. It is important to expect the interference in grating interferometer compared normal nondestructive system. In this paper, simulation works are conducted according to Talbot and Talbot-Lau interferometer in case of X-ray and Neutron. Variation of interference intensity with X-ray and Neutron based on wave theory is constructed and calculate elements consist the system. Additionally, Talbot and Talbot-Lau interferometer is simulated in different kinds of conditions.

  4. Optimization of direct-write polarization gratings

    Miskiewicz, Matthew N.; Escuti, Michael J.


    We recently reported on a mathematical formalism for analyzing the result of a direct-write scanning system applied to photoaligned liquid crystal films. We use that formalism to study the direct-write recording of polarization gratings (PGs). First, we evaluate three scan paths in simulation and experiment, describe their tradeoffs and practical constraints, and identify the most favorable. Second, we explore the parameter space of direct-write PGs in simulation, which includes four dimensions in general: grating period, line spacing, beam size, and spatially averaged fluence. Using this analysis, we predict that a certain portion of the parameter space should be optimal, leading to high diffraction efficiency and well-aligned PGs. Finally, we experimentally fabricate and characterize nine PGs with scan parameters within and around this optimal parameter space and conclude that the prediction is validated. This work is the first in-depth study of direct-write PGs; it identifies many challenges and solutions, and shows, for the first time, direct-write recorded PGs with quality equivalent to those recorded via holography. In particular, we demonstrate a PG (20 μm period) with first-order diffraction efficiency 99.5%, 0.2% haze, and polarization contrast of 2000.

  5. Holographic dielectric grating: theory and practice.

    Chang, M; George, N


    Lossy dielectric gratings have been analyzed using a Raman-Nath formalism modified to incorporate losses. Four second-order coupled wave equations are retained for computation of the zero, first- and second-order diffracted beams for a multitude of practical cases. Significant differences are found in comparison with computations in which only two coupled waves are retained. The entire range of losses and thicknesses encountered for holograms in film emulsions has been studied using this unified approach. Graphs have been prepared to show the efficiency, i.e., power diffracted in the first-order relative to the total incident power, vs the index modulation for a wide range of thicknesses and losses. At a given thickness, optimum frequency requires a specific exposure. The efficiency for an optimum exposure is plotted vs the loss factor with thickness as a parameter. New experimental data are presented for bleached gratings in which several diffracted orders are measured and compared to our theory for a wide range of index modulation and loss factors.

  6. Optimization of top polymer gratings to improve GaN LEDs light transmission

    Xiaomin Jin; Bei Zhang; Tao Dai; Wei Wei; Xiangning; Guoyi Zhang; Simeon Trieu; Fei Wang


    @@ We present a grating model of two-dimensional (2D) rigorous coupled wave analysis (RCWA) to study top diffraction gratings on light-emitting diodes(LEDs). We compare the integrated-transmission of the non-grating,rectangular-grating,and triangular-grating cases for the same grating period of 6μm,and show that the triangular grating has the best performance. For the triangular grating with 6-μmperiod, the LED achieves the highest light transmission at 6-μ gratingbottom width and 2.9-μm grating depth. Compared with the non-grating case, the optimized light transmission improvement is about 74.6%.The simulation agrees with the experimental data of the thin ploymer grating encapsulated flip-chip(FC) GaN-based LEDs for the light extraction improvement.

  7. VA administrators breahe a sigh of relief

    Robbins RA


    Full Text Available No abstract available. Article truncated at 150 words. On May 30, Eric Shinseki, the Secretary for Veterans Affairs (VA, resigned under pressure amidst a growing scandal regarding falsification of patient wait times at nearly 40 VA medical centers. Before leaving office Shinseki fired Sharon Helman, the former hospital director at the Phoenix VA, where the story first broke, along with her deputy and another unnamed administrator. In addition, Susan Bowers, director of VA Veterans Integrated Service Network (VISN 18 and Helman’s boss, resigned. Robert Petzel, undersecretary for the Veterans Health Administration (VHA, head of the VA hospitals and clinics, had resigned earlier. You could hear the sigh of relief from the VA administrators. With their bosses resigning left and right, the VA leadership in shambles and the reputation of the VA soiled for many years to come, why are the VA administrators relieved? The simple answer is that nothing has really changed. There for a moment it looked ...

  8. Relief of diabetic neuropathy with fluoxetine.

    Theesen, K A; Marsh, W R


    A 31-year-old woman with advanced diabetes mellitus with secondary autonomic and peripheral neuropathy was admitted for treatment of major depression. Previous therapy with desipramine resulted in exacerbation of the patient's orthostatic hypotension. After admission to the psychiatric facility she was initially stabilized medically and treated with psychotherapy. Subsequent treatment with low-dose fluoxetine 5 mg resulted in a decrease of the patient's diabetic neuropathy pain. Further increases in the fluoxetine dosage resulted in improvement of her depression and increased pain relief. Therapy with fluoxetine did not result in exacerbation of the orthostatic hypotension. This preliminary case report indicates that fluoxetine may be an alternative to the tricyclic antidepressants and trazodone in the treatment of diabetic peripheral neuropathy.

  9. Objective Crystal Spectrometer on the SRG satellite

    Christensen, Finn Erland; Westergaard, Niels Jørgen Stenfeldt; Rasmussen, I.


    The flight version of the Objective Crystal Spectrometer (OXS) on the SPECTRUM-X- GAMMA satellite is presented. The spectrometer is a panel that is placed in front of one of the SODART telescopes. It is composed of an array of the three Bragg crystals, LiF(220), Si(111) and RAP(001) for high...

  10. SODART optical block of the SRG satellite

    Christensen, Finn Erland; Frederiksen, P.; Polny, Josef


    This paper describes the design and the successful integration of the optical block of the SODART telescopes to be flown on the Spectrum Roentgen Gamma satellite. The integration involves both the integration of the two high throughput x-ray telescopes as well as the objective crystal spectrometer....... The integrated unit meets all mechanical, thermal and optical specifications and it is now in safe storage in Moscow and awaits further integration procedures with the remaining satellite structure....

  11. The Interaction of Optical Guided Modes with Waveguide Diffraction Gratings.

    Weller-Brophy, Laura Ann

    In this thesis the results of a theoretical and experimental investigation of the coupling of guided modes by waveguide gratings are presented. This work is motivated by the potential application of waveguide gratings to integrated optical devices. The coupling of guided modes obliquely incident to both periodic and aperiodic gratings is a mechanism basic to the operation of integrated optical components such as filters, reflectors, beamsplitters, and modulators. It is shown in the Introduction to this thesis, that this mechanism is not modeled consistently by the analyses presented in the literature. For the case of TM-TM coupling, virtually each analytical treatment predicts a different value for the grating reflectivity. In addition, it is found that the typical Coupled-Mode formalisms used to derive the grating reflectivity do not offer an intuitive picture of the operation of waveguide gratings. These two particular problem areas serve as the focal points of this thesis. The latter of these is addressed through the development of a thin film model of the operation of waveguide gratings. This model presents an intuitively appealing picture of the interaction of waveguide gratings and guided modes. It also yields grating reflectivities which are in excellent agreement with those obtained through the numerical solution of the Coupled-Mode equations for both periodic and aperiodic gratings. The bulk of this research project is directed towards resolving the conflicting theoretical grating analyses presented in the literature. A new derivation of the coupling of guided modes obliquely incident to periodic gratings is presented in Chapter II of this thesis. This derivation is based on the Local Normal Mode expansion used by Marcuse for the case of normal incidence. It produces coupling coefficients which are nearly identical to those derived using the rigorous Boundary Perturbation technique. The coupling coefficients predicted by this Local Normal Mode formalism

  12. Hurricane Relief Operations in the Caribbean: Is the Use of the Military in Hurricane Relief Operations


    Caribbean hurricanes are a type of tropical cyclone . They originate in the Atlantic Ocean off the coast of Africa and affect the Caribbean and 2 the...that will prove to be more suitable in disaster relief situations. Matthew Yarrow also shares Dynes’ view. He believes that soldiers are ill-suited... Haiti operations, in part due to the battalion commander’s lack of authority over troops from different countries. However, the performance of the

  13. 46 CFR 56.50-20 - Pressure relief piping.


    ... 46 Shipping 2 2010-10-01 2010-10-01 false Pressure relief piping. 56.50-20 Section 56.50-20 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND APPURTENANCES Design Requirements Pertaining to Specific Systems § 56.50-20 Pressure relief piping. (a)...

  14. Donation to disaster relief campaigns: underlying social cognitive factors exposed

    Oosterhof, Liesbeth; Heuvelman, Ard; Peters, Oscar


    number of very serious natural disasters have put an enormous pressure on relief organizations in the last few years. The present study exposes underlying social cognitive factors for donation to relief campaigns. A causal model was constructed, based on social cognitive theory, research on attitude

  15. Ethiopian Relief: A Case Study in Failed Public Relations.

    Chapel, Gage W.


    Examines how InterAid, a private-sector relief agency, responded to the false charge that it had misappropriated $20 million purportedly raised for Ethiopian famine relief. Suggests that it was not primarily negative reporting that retarded the strength of InterAid, but InterAid's inability to demonstrate shared common interests with its primary…

  16. Donation to disaster relief campaigns: underlying social cognitive factors exposed

    Oosterhof, Liesbeth; Heuvelman, A.; Peters, O.


    number of very serious natural disasters have put an enormous pressure on relief organizations in the last few years. The present study exposes underlying social cognitive factors for donation to relief campaigns. A causal model was constructed, based on social cognitive theory, research on attitude

  17. 46 CFR 193.15-40 - Pressure relief.


    ... 46 Shipping 7 2010-10-01 2010-10-01 false Pressure relief. 193.15-40 Section 193.15-40 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OCEANOGRAPHIC RESEARCH VESSELS FIRE PROTECTION EQUIPMENT Carbon Dioxide Extinguishing Systems, Details § 193.15-40 Pressure relief. (a) Where necessary...

  18. Emergency Relief for Teachers of Children Who Challenge

    Crow, René; Cooper, Mark; Dallas, Jamie


    Teachers of students with chronic challenging behaviors need relief, and they need it quickly. While they may appreciate the sympathy of others, what they really need is some genuine help. Challenging children can make a teacher's day difficult. In this article, the authors share some strategies that can provide "emergency relief" to…

  19. 46 CFR 154.517 - Piping: Liquid pressure relief.


    ... 46 Shipping 5 2010-10-01 2010-10-01 false Piping: Liquid pressure relief. 154.517 Section 154.517 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY... and Process Piping Systems § 154.517 Piping: Liquid pressure relief. The cargo loading and discharge...

  20. 46 CFR 76.15-40 - Pressure relief.


    ... 46 Shipping 3 2010-10-01 2010-10-01 false Pressure relief. 76.15-40 Section 76.15-40 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PASSENGER VESSELS FIRE PROTECTION EQUIPMENT Carbon Dioxide Extinguishing Systems, Details § 76.15-40 Pressure relief. (a) Where necessary, relatively...

  1. 46 CFR 95.15-40 - Pressure relief.


    ... 46 Shipping 4 2010-10-01 2010-10-01 false Pressure relief. 95.15-40 Section 95.15-40 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS FIRE PROTECTION EQUIPMENT Carbon Dioxide Extinguishing Systems, Details § 95.15-40 Pressure relief. (a) Where necessary...

  2. 40 CFR 1042.850 - Exemptions and hardship relief.


    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Exemptions and hardship relief. 1042.850 Section 1042.850 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Special Provisions for Remanufactured Marine Engines § 1042.850 Exemptions and hardship relief. This...

  3. 12 CFR 742.4 - RegFlex Relief.


    ... 12 Banks and Banking 6 2010-01-01 2010-01-01 false RegFlex Relief. 742.4 Section 742.4 Banks and Banking NATIONAL CREDIT UNION ADMINISTRATION REGULATIONS AFFECTING CREDIT UNIONS REGULATORY FLEXIBILITY PROGRAM § 742.4 RegFlex Relief. (a) Exemptions. RegFlex credit unions are exempt from the following...

  4. Theoretical Investigation of Subwavelength Gratings and Vertical Cavity Lasers Employing Grating Structures

    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......-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...... more guided mode resonances (GMRs) in the reflectivity spectrum. The fabrication tolerance of the HG is investigated numerically, which shows that the broadband near-unity reflectivity characteristic is prone to common fabrication errors. An experimental demonstration of the HG reflector confirms its...

  5. High efficiency diffraction grating for EUV lithography beamline monochromator

    Voronov, D. L.; Warwick, T.; Gullikson, E. M.; Salmassi, F.; Naulleau, P.; Artemiev, N. A.; Lum, P.; Padmore, H. A.


    A blazed diffraction grating for the EUV lithography Beamline 12.0.1 of the Advanced Light Source has been fabricated using optical direct write lithography and anisotropic wet etching technology. A variable line spacing pattern was recorded on a photoresist layer and transferred to a hard mask layer of the grating substrate by a plasma etch. Then anisotropic wet etching was applied to shape triangular grating grooves with precise control of the ultralow blaze angle. Variation of the groove density along the grating length was measured with a Long Trace Profiler (LTP). Fourier analysis of the LTP data confirmed high groove placement accuracy of the grating. The grating coated with a Ru coating demonstrated diffraction efficiency of 69.6% in the negative first diffraction order which is close to theoretical efficiency at the wavelength of 13.5 nm. This work demonstrates an alternative approach to fabrication of highly efficient and precise x-ray diffraction gratings with ultra-low blaze angles.

  6. High-resolution diffraction grating interferometric transducer of linear displacements

    Shang, Ping; Xia, Haojie; Fei, Yetai


    A high-resolution transducer of linear displacements is presented. The system is based on semiconductor laser illumination and a diffraction grating applied as a length master. The theory of the optical method is formulated using Doppler description. The relationship model among the interference strips, measurement errors, grating deflection around the X, Y and Z axes and translation along the Z axis is built. The grating interference strips' direction and space is not changed with movement along the X (direction of grating movement), Y (direction of grating line), Z axis, and the direction and space has a great effect when rotating around the X axis. Moreover the space is little affected by deflection around the Z axis however the direction is changed dramatically. In addition, the strips' position shifted rightward or downwards respectively for deflection around the X or Y axis. Because the emitted beams are separated on the grating plane, the tilt around the X axis error of the stage during motion will lead to the optical path difference of the two beams resulting in phase shift. This study investigates the influence of the tilt around the X axis error. Experiments show that after yaw error compensation, the high-resolution diffraction grating interferometric transducer readings can be significantly improved. The error can be reduced from +/-80 nm to +/-30 nm in maximum.

  7. Suppressing Ghost Diffraction in E-Beam-Written Gratings

    Wilson, Daniel; Backlund, Johan


    A modified scheme for electron-beam (E-beam) writing used in the fabrication of convex or concave diffraction gratings makes it possible to suppress the ghost diffraction heretofore exhibited by such gratings. Ghost diffraction is a spurious component of diffraction caused by a spurious component of grating periodicity as described below. The ghost diffraction orders appear between the main diffraction orders and are typically more intense than is the diffuse scattering from the grating. At such high intensity, ghost diffraction is the dominant source of degradation of grating performance. The pattern of a convex or concave grating is established by electron-beam writing in a resist material coating a substrate that has the desired convex or concave shape. Unfortunately, as a result of the characteristics of electrostatic deflectors used to control the electron beam, it is possible to expose only a small field - typically between 0.5 and 1.0 mm wide - at a given fixed position of the electron gun relative to the substrate. To make a grating larger than the field size, it is necessary to move the substrate to make it possible to write fields centered at different positions, so that the larger area is synthesized by "stitching" the exposed fields.

  8. Characterization of the holographic imaging grating of GOMOS UVIS spectrometer

    Graeffe, Jussi; Saari, Heikki K.; Astola, Heikki; Rainio, Kari; Mazuray, Lorand; Pierot, Dominique; Craen, Pierre; Gruslin, Michel; Lecat, Jean-Herve; Bonnemason, Francis; Flamand, Jean; Thevenon, Alain


    A Finnish-French group has proposed an imaging spectrometer- based instrument for the ENVISAT Earth observation satellite of ESA, which yields a global mapping of the vertical profile of ozone and other related atmospheric gases. The GOMOS instrument works by measuring the UV-visible spectrum of a star that is occulting behind the Earth's atmosphere. The prime contractor of GOMOS is Matra Marconi Space France. The focal plane optics are designed and manufactured by Spacebel Instrumentation S.A. and the holographic grating by Jobin-Yvon. VTT Automation, Measurement Technology has participated in the GOMOS studies since 1989 and is presently responsible for the verification tests of the imaging quality and opto-mechanical interfaces of the holographic imaging grating of GOMOS. The UVIS spectrometer of GOMOS consists of a holographic, aberration corrected grating and of a CCD detector. The alignment of the holographic grating needs as an input very accurate knowledge of the mechanical interfaces. VTT Automation has designed, built and tested a characterization system for the holographic grating. This system combines the accurate optical imaging measurements with the absolute knowledge of the geometrical parameters at the accuracy of plus or minus 10 micrometers which makes the system unique. The developed system has been used for two breadboard gratings and the qualification model grating. The imaging quality results and their analysis together with alignment procedure utilizing of the knowledge of mechanical interfaces is described.

  9. Metal-coated Bragg grating reflecting fibre

    Chamorovskiy, Yu. K.; Butov, O. V.; Kolosovskiy, A. O.; Popov, S. M.; Voloshin, V. V.; Vorob'ev, I. L.; Vyatkin, M. Yu.


    High-temperature optical fibres (OF) with fibre Bragg gratings (FBG) arrays written over a long length and in-line metal coating have been made for the first time. The optical parameters of the FBG arrays were tested by the optical frequency domain reflectometer (OFDR) method in a wide temperature range, demonstrating no degradation in reflection at heating up to 600 °C for a fibre with Al coating. The mechanical strength of the developed fibre was practically the same as "ordinary" OF with similar coating, showing the absence of the influence of FBG writing process on fibre strength. Further experiments are necessary to evaluate the possibility of further increases in the operational temperature range.

  10. Optical Fiber Bragg Grating Michelson Interferometer

    JIANG Yi; JIANG Tian-fu; LIU Li


    A new Michelson interferometer based on fiber Bragg grating(FBG) is demonstrated. FBGs are used as reflectors, and the laser is replaced by a broadband source as input light in this interferometer. To demodulate the signals, a 3×3 coupler is used as a splitter. By combining with software demodulation, the outer inter ference can be obtained from the outputs of the interferometer. This kind of in terferometer can also be wavelength-multiplexed easily by composing a series Michelson interferometer. The experiment results show that the clear interference fringe can be obtained by adjusting the path difference to make it less than interference length of FBG. The signals are also demodulated.

  11. Blazed Gratings Recorded in Absorbent Photopolymers

    Roberto Fernández


    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.

  12. Grating-based tomography of human tissues

    Müller, Bert; Schulz, Georg; Mehlin, Andrea; Herzen, Julia; Lang, Sabrina; Holme, Margaret; Zanette, Irene; Hieber, Simone; Deyhle, Hans; Beckmann, Felix; Pfeiffer, Franz; Weitkamp, Timm


    The development of therapies to improve our health requires a detailed knowledge on the anatomy of soft tissues from the human body down to the cellular level. Grating-based phase contrast micro computed tomography using synchrotron radiation provides a sensitivity, which allows visualizing micrometer size anatomical features in soft tissue without applying any contrast agent. We show phase contrast tomography data of human brain, tumor vessels and constricted arteries from the beamline ID 19 (ESRF) and urethral tissue from the beamline W2 (HASYLAB/DESY) with micrometer resolution. Here, we demonstrate that anatomical features can be identified within brain tissue as well known from histology. Using human urethral tissue, the application of two photon energies is compared. Tumor vessels thicker than 20 μm can be perfectly segmented. The morphology of coronary arteries can be better extracted in formalin than after paraffin embedding.

  13. Review of High-Speed Fiber Optic Grating Sensors Systems

    Udd, E; Benterou, J; May, C; Mihailov, S J; Lu, P


    Fiber grating sensors can be used to support a wide variety of high speed measurement applications. This includes measurements of vibrations on bridges, traffic monitoring on freeways, ultrasonic detection to support non-destructive tests on metal plates and providing details of detonation events. This paper provides a brief overview of some of the techniques that have been used to support high speed measurements using fiber grating sensors over frequency ranges from 10s of kHz, to MHZ and finally toward frequencies approaching the GHz regime. Very early in the development of fiber grating sensor systems it was realized that a high speed fiber grating sensor system could be realized by placing an optical filter that might be a fiber grating in front of a detector so that spectral changes in the reflection from a fiber grating were amplitude modulated. In principal the only limitation on this type of system involved the speed of the output detector which with the development of high speed communication links moved from the regime of 10s of MHz toward 10s of GHz. The earliest deployed systems involved civil structures including measurements of the strain fields on composite utility poles and missile bodies during break tests, bridges and freeways. This was followed by a series of developments that included high speed fiber grating sensors to support nondestructive testing via ultrasonic wave detection, high speed machining and monitoring ship hulls. Each of these applications involved monitoring mechanical motion of structures and thus interest was in speeds up to a few 10s of MHz. Most recently there has been interest in using fiber grating to monitor the very high speed events such as detonations and this has led to utilization of fiber gratings that are consumed during an event that may require detection speeds of hundreds of MHz and in the future multiple GHz.

  14. Geometric-Phase Polarization Fan-out Grating Fabricated with Deep-UV Interference Lithography

    Wan, Chenhao; Lombardo, David; Sarangan, Andrew; Zhan, Qiwen


    We report the design, fabrication and testing of a highly efficient polarization fan-out grating for coherent beam combining working at 1550 nm. The grating design exploits the geometric-phase effect. Deep-UV interference lithography is used to fabricate the designed grating. Such a polarization fan-out grating demonstrates several advantages that are ideal for laser beam combining.

  15. Enhanced surface plasmon polariton propagation length using a buried metal grating

    Jose, J.; Segerink, Franciscus B.; Korterik, Jeroen P.; Gomez Casado, A.; Huskens, Jurriaan; Herek, Jennifer Lynn; Offerhaus, Herman L.


    We report an enhancement in the propagation length of surface plasmon polaritons (SPPs) on a metallic grating when the grating is buried in the substrate. A template-stripping technique has been used to fabricate the buried grating. Near-field measurements on the buried and an exposed grating show

  16. An echelle diffraction grating for imaging spectrometer

    Yang, Minyue; Wang, Han; Li, Mingyu; He, Jian-Jun


    We demonstrate an echelle diffraction grating (EDG) of 17 input waveguides and 33 output waveguides. For each input waveguide, only 17 of 33 output waveguides are used, receiving light ranging from 1520 nm to 1600 nm wavelength. The channel spacing of the EDG is 5 nm, with loss of -6dB and crosstalk of -17dB for center input waveguide and -15dB for edge input waveguides. Based on the 3 μm SOI platform the device is polarization insensitive. As a simple version of EDG spectrometer it is designed to be a part of the on-chip spectroscopic system of the push-broom scanning imaging spectrometer. The whole on-chip spectrometer consists of an optical on-off switch array, a multi-input EDG and detector array. With the help of on-off switch array the multiple input waveguides of the EDG spectrometer could work in a time division multiplexed fashion. Since the switch can scan very fast (less than 10 microseconds), the imaging spectrometer can be operated in push-broom mode. Due to the CMOS compatibility, the 17_channel EDG scales 2.5×3 mm2. The full version of EDG spectrometer is designed to have 129 input waveguides and 257 output waveguides (129 output channel for each input waveguide), working in wavelength ranging from 1250 nm to 1750 nm, and had similar blazed facet size with the 17_channel one, which means similar fabrication tolerance in grating facets. The waveguide EDG based imaging spectrometer can provide a low-cost solution for remote sensing on unmanned aerial vehicles, with advantages of small size, light weight, vibration-proof, and high scalability.

  17. United Airlines Assists Tsunami Relief Effort United donates cargo space for relief supplies going to southern Asia


    @@ United Airlines today announced several initiatives to assist with the tsunami relief effort in Asia, including the donation of available cargo space to ship relief supplies to southern Thailand,Indonesia, Sri Lanka and other coastal areas on the Indian Ocean.

  18. United Airlines Assists Tsunami Relief Effort United donates cargo space for relief supplies going to southern Asia


      United Airlines today announced several initiatives to assist with the tsunami relief effort in Asia, including the donation of available cargo space to ship relief supplies to southern Thailand,Indonesia, Sri Lanka and other coastal areas on the Indian Ocean.……

  19. Holographic liquid crystal polarization grating with Fabry-Perot structure.

    Sakamoto, Moritsugu; Yamaguchi, Haruki; Noda, Kohei; Sasaki, Tomoyuki; Kawatsuki, Nobuhiro; Ono, Hiroshi


    A holographic liquid crystal polarization grating with a Fabry-Perot structure was developed. Because of its resonant structure, the device offers high levels of control of the diffraction properties of incident-polarized light beams, depending on the resonance conditions. The diffracted light beams are emitted in both the reflection and transmission directions, and the device thus works as a multibranch polarization grating with double optical paths, unlike a conventional polarization grating. These device features were experimentally demonstrated and were also explained theoretically.

  20. Thermally tunable grating using thermo-responsive magnetic fluid

    Zaibudeen, A. W.; Philip, John


    We report a thermally tunable grating prepared using poly(N-isopropylacrylamide) and super paramagnetic iron oxide nanoparticles. The array spacing is reversibly tuned by varying the temperature between 5 and 38 °C. Here, the ability of thermo-responsive polymer brushes to alter their conformation at an interface is exploited to control the grating spacing in nanoscale. The underlying mechanism for the temperature dependent conformational changes are studied by measuring the subtle intermolecular forces between the polymer covered interfaces. It is observed that the interparticle forces are repulsive and exponentially decaying with distance. The thermo-responsive grating is simple to use and offers a wide range of applications.

  1. A reconfigurable optofluidic Michelson interferometer using tunable droplet grating.

    Chin, L K; Liu, A Q; Soh, Y C; Lim, C S; Lin, C L


    This paper presents a novel optofluidic Michelson interferometer based on droplet microfluidics used to create a droplet grating. The droplet grating is formed by a stream of plugs in the microchannel with constant refractive index variation. It has a real-time tunability in the grating period through varying the flow rates of the liquids and index variation via different combinations of liquids. The optofluidic Michelson interferometer is highly sensitive and is suitable for the measurement of biomedical and biochemical buffer solutions. The experimental results show that it has a sensitivity of 66.7 nm per refractive index unit (RIU) and a detection range of 0.086 RIU.

  2. Photonic crystal fiber long-period gratings for biochemical sensing

    Rindorf, Lars Henning; Jensen, Jesper Bo; Dufva, Hans Martin


    -period grating it was possible to measure the thickness of the layer. The long-period gratings were inscribed in a large-mode area silica photonic crystal fiber with a CO2 laser. The thicknesses of a monolayer of poly-L-lysine and double-stranded DNA was measured using the device. We find that the grating has...... a sensitivity of approximately 1.4nm/1nm in terms of the shift in resonance wavelength in nm per nm thickness of biomolecule layer....

  3. On the Intensity Distribution Function of Blazed Reflective Diffraction Gratings

    Casini, R


    We derive from first principles the expression for the angular/wavelength distribution of the intensity diffracted by a blazed reflective grating, according to a scalar theory of diffraction. We considered the most common case of a groove profile with rectangular apex. Our derivation correctly identifies the geometric parameters of a blazed reflective grating that determine its diffraction efficiency, and fixes an incorrect but commonly adopted expression in the literature. We compare the predictions of this scalar theory with those resulting from a rigorous vector treatment of diffraction from one-dimensional blazed reflective gratings.

  4. Optical fibre grating refractometers for resin cure monitoring

    Buggy, S. J.; Chehura, E.; James, S. W.; Tatam, R. P.


    The use of fibre grating refractometers as a means of monitoring the cure of a UV-cured 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 × 10-3 rius) and illustrate the potential of the techniques for non-invasive composite material cure monitoring.

  5. Ultrafast laser inscribed fiber Bragg gratings for sensing applications

    Mihailov, Stephen J.


    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 femtosecond infrared laser-material 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 tutorial paper will present a review of some of the more recent developments.

  6. Single-grating laser pulse stretcher and compressor.

    Lai, M; Lai, S T; Swinger, C


    Stretching and compressing of laser pulses is demonstrated with a single-grating apparatus. A laser pulse of 110 fs is stretched to 250 ps and then recompressed to 115 fs. The apparatus exploits a two-level structure: one level for stretching and the other for compressing. This single-grating configuration shows significant simplification in structure and alignment over existing multiple-grating systems. Such a stretcher-compressor is particularly suitable for use with chirped-pulse amplification in which laser wavelength tuning is desirable. Only one rotational adjustment is rquired to restore the alignment of the entire stretcher and compressor when the laser wavelength is changed.

  7. Fiber Grating Sensor with Enhanced Pressure and Temperature Sensitivity

    LIU Yun-Qi; GUO Zhuan-Yun; LIU Zhi-Guo; ZHAO Dong-Hui; GE Chun-Feng; DONG Xiao-Yi


    A technique is used to enhance the pressure and temperature sensitivity of a fiber Bragg grating sensor. The grating is packaged by using polymer jacket, which exhibits no significant chirp due to the adoption of the special technique. The measured pressure and temperature sensitivity of the structured grating is 6.28×10-5 / MPa and5.18×10-5/℃. The wavelength shift due to pressure and temperature can be enhanced about 31.5 times for pressure and 7.7 times for temperature.

  8. Single and Multiple Phase Shifts Tilted Fiber Bragg Gratings

    Christophe Caucheteur


    Full Text Available The spectral behavior of single and multiple phase shifts tilted fiber Bragg gratings has been experimentally investigated. To this aim, a simple and cost-effective postprocessing technique based on local thermal treatment was used to create arbitrary phase shifts along the tilted grating structure. In particular, UV written tilted fiber Bragg gratings were treated by the electric arc discharge to erase the refractive index modulation in well-defined regions. We demonstrate that these defects give rise to interference pattern for all modes, and thus defect states can be achieved within all the attenuation bands, enabling a simple wavelength independent spectral tailoring of this class of devices.

  9. Bragg grating chemical sensor with hydrogel as sensitive element

    Xiaomei Liu(刘小梅); Shilie Zheng(郑史烈); Xianmin Zhang(章献民); Jun Cong(丛军); Kangsheng Chen(陈抗生); Jian Xu(徐坚)


    A novel fiber Bragg grating (FBG) based chemical sensor using hydrogel, a swellable polymer, as sensitive element is demonstrated. The sensing mechanism relies on the shift of Bragg wavelength due to the stress resulted from volume change of sensitive swellable hydrogel responding to the change of external environment. A polyacrylamide hydrogel fiber grating chemical sensor is made, and the experiments on its sensitivity to the salinity are performed. The sensitivity is low due to the less stress from the shrinking or swelling of hydrogels. Reducing the cross diameter of the grating through etching with hydrofluoric acid can greatly improve the sensitivity of the sensor.

  10. Numerical modelling of a straw-fired grate boiler

    Kær, Søren Knudsen


    The paper presents a computational fluid dynamics (CFD) analysis of a 33 MW straw-fired grate boiler. Combustion on the grate plays akey-role in the analysis of these boilers and in this work a stand-alone code was used to provide inlet conditions for the CFD analysis. Modelpredictions were...... compared with available gas temperature and species concentration measurements showing good agreement. Combustionof biomass in grate-based boilers is often associated with high emission levels and relatively high amounts of unburnt carbon in the fly ash.Based on the CFD analysis, it is suggested that poor...

  11. Fabrication and characterization of sandwiched optical fibers with periodic gratings.

    Chiang, Chia-Chin


    This study proposes a novel process for fabricating a sandwiched long-period fiber grating (SLPFG) using a SU-8 thick photoresist technique. The SLPFG consists of a thin cladding optical fiber sandwiched with a double-sided periodical grating coating. By varying the external loads on the SLPFG, the transmission dip of the resonance wavelength is tuned according to a squared-harmonic curve. The SLPFG can thus be utilized as a loss tunable filter or sensor. The resonance dip wavelength is related to the cladding thicknesses of the optical fiber and the periods of the grating. A maximum transmission resonant dip of 34.61dB was achieved.

  12. Deep-groove nickel gratings for solar thermal absorbers

    Ahmad, N.; Núñez-Sánchez, S.; Pugh, J. R.; Cryan, M. J.


    This paper presents measured and modelled optical absorptance and reflectance for deep-groove nickel nano-gratings in the 450-950 nm wavelength range. The structures have been fabricated using focused ion beam etching and characterised using Fourier spectroscopy and the field distributions on the gratings have been studied using finite difference time domain modelling. Realistic grating structures have been modelled based on focused ion beam cross sections and these results are in good agreement between measured and modelled results. The roles of surface plasmon polaritons and slot modes are highlighted in the strong broadband absorbance that can be achieved with these structures.

  13. Temporal characteristics of polarization holographic gratings formed in a photosensitive polymeric film containing N-benzylideneaniline derivative side groups

    Sasaki, Tomoyuki; Shoho, Takashi; Noda, Kohei; Kawatsuki, Nobuhiro; Ono, Hiroshi


    A polarization holographic grating was recorded in a transparent thin film formed from polymethacrylate with N-benzylideneaniline (NBA) derivative side groups. We measured the real time diffraction properties. The data were analyzed based on a theoretical model that accounted for the distribution of optical anisotropy caused by molecular reorientation as well as for surface relief (SR) deformation caused by molecular motion. Optical anisotropy rapidly increased and then slowly decreased, with increasing recording time. This phenomenon was described based on photoisomerization and photocleavage reactions of the NBA side groups. SR deformation was also induced in the film by polarization holographic recording, without any subsequent processes. The photoinduced optical anisotropy and SR deformation were retained after the recording was turned off.

  14. Donation to disaster relief campaigns: underlying social cognitive factors exposed.

    Oosterhof, Liesbeth; Heuvelman, Ard; Peters, Oscar


    A number of very serious natural disasters have put an enormous pressure on relief organizations in the last few years. The present study exposes underlying social cognitive factors for donation to relief campaigns. A causal model was constructed, based on social cognitive theory, research on attitudes, and the impact of media exposure. The aim was to expand and improve an already existing model by Cheung and Chan [Cheung, C. K., & Chan, C. M. (2000). Social-cognitive factors of donating money to charity, with special attention to an international relief organisation. Evaluation and Program Planning, 23, 241-253]. The expanded model showed a better fit. Furthermore, the expanded model explained two-thirds of the variance of the intention to donate to a disaster relief campaign. The greatest predictor of the intention to donate proved to be "Past donation to disaster relief campaigns." The factor "News exposure" was indicated to be a valuable additional factor, as it had a significant direct effect on "Awareness of a disaster relief campaign" and was the only factor that had a total effect on all other factors, including "Intention to donate to a disaster relief campaign."

  15. A Real-Time Decision Support System for Anesthesiologist End-of-Shift Relief.

    Wax, David B; McCormick, Patrick J


    A decision support system using recent data about work hours and real-time data about relief events was developed to guide anesthesiologist end-of-shift relief decisions in an effort to promote a relief order that prioritized relief for those who had recently worked later than others. After system implementation, there were fewer deviations from this idealized order of relief, and early relief was more evenly distributed.

  16. Recent progress in the development of pulse compression gratings

    Hocquet S.


    Full Text Available The PETAL facility uses chirped pulse amplification (CPA technique. This system needs large pulse compression gratings that request damage threshold better than 4 J/cm2 in normal beam at 1.053 μm for 500 fs pulses. In this paper, we will show recent grating designs with either multilayer dielectrics or hybrid metal-dielectric structures. We have shown in previous works that damage threshold is driven by the enhancement of the near electric field inside the pillars of the grating. This was evidenced from a macroscopic point of view by means of laser damage testing. We will show that damage morphology during damage initiation at the scale of the grating groove is also consistent with this electric field dependence.

  17. UV writing of advanced Bragg gratings in optical waveguides

    Jensen, Jesper Bo Damm


    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...... of the novel polarization control method for UV writing of Bragg gratings with advanced apodization profiles including phase shifts. The principle of the polarization control method relies on a spatial separation of the s- and p-polarized components of a linearly polarized UV beam corresponding to half...... 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...

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

    Stegenburgs, Edgars


    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.

  19. Fiber optical Bragg grating sensors embedded in CFRP wires

    Nellen, Philipp M.; Frank, Andreas; Broennimann, Rolf; Meier, Urs; Sennhauser, Urs J.


    Based on the example application of Emmenbridge, a newly built steel-concrete-composite bridge in Switzerland with 47 m long built-in carbon fiber reinforced polymer (CFRP) prestressing cables, we will present and analyze the process chain leading to a reliable surveillance of modern civil engineering structures with embedded fiber optical Bragg gratings. This consists first in the embedding of optical fibers and in-fiber Bragg gratings in long CFRP wires in an industrial environment, including fiber optical monitoring of the curing process. Then, various qualifying tests were done: annealing experiments for determining optical lifetime of the Bragg gratings used, dynamic and static tensile tests for estimating their mechanical lifetime under operation, push-out experiments to check adhesion of fiber/coating/matrix interfaces, and performance tests to determine strain and temperature sensitivity of the embedded Bragg gratings. Finally, the prestressing cables were equipped with the CFRP sensor wires and built into the bridge.

  20. Long-Period Gratings in Planar Optical Waveguides

    Kin; Seng; Chiang


    Our progress in the study of long-period gratings (LPGs) in planar optical waveguides is reviewed. In particular, experimental LPGs in glass and polymer waveguides are presented to demonstrate the potential of LPG-based waveguide devices.

  1. Long-Period Gratings in Planar Optical Waveguides

    Kin Seng Chiang


    Our progress in the study of long-period gratings (LPGs) in planar optical waveguides is reviewed. In particular,experimental LPGs in glass and polymer waveguides are presented to demonstrate the potential of LPG-based waveguide devices.

  2. Fabrication of integrated waveguide grating in azo polymers.

    Jalilpiran, Saber; Karimi-Alavijeh, Hamidreza; Katebi-Jahromi, Alireza; Gharavi, Alireza


    In this Letter, we have introduced a technique, new to our knowledge, to fabricate gratings on a waveguide of azo-functionalized polymeric films using a slit mask and a fast, direct-writing method. To prevent the destruction of the waveguide by the grating formation on the waveguide, we placed a slit mask on the waveguide. By properly adjusting the resonance, this grating can be used as an integrated wavelength filter. We have produced an attenuation of 13.4 dB at 1562 nm with a FWHM of 3.45 nm. The grating has been fabricated as narrow as the width of the waveguide to couple filtered light into the waveguide by using a slit mask. Any light shifted from the resonance will pass through the waveguide undisturbed.

  3. A bistable system with an electromagnetically induced grating

    苏雪梅; 卓仲畅; 王立军; 高锦岳


    We propose a scheme of a bistable system with an electromagnetically induced grating and analyse the opticalbistabilities in the system. The stationary equations describing the system have been derived. This bistable systemshows typical hysteresis behaviour.

  4. Photowritten gratings in ion-exchanged glass waveguides.

    Roman, J E; Winick, K A


    The fabrication of an ion-exchanged waveguide beam deflector containing a photowritten grating is described. The planar waveguide was fabricated by thermal K(+) exchange in a borosilicate glass. The grating was written by photobleaching an absorption defect centered at 330 am, which was created by gamma-ray irradiation of the glass. The bleaching was accomplished with the 351-nm line from an argon laser. The device achieved 35% deflection efficiency at 633 nm, which corresponded to a grating with a photoinduced index change of 2.6 x 10(-5). This is to our knowledge the first demonstration of an ion-exchanged glass waveguide device containing a permanent photowritten grating.

  5. Performance of volume phase gratings manufactured using ultrafast laser inscription

    Lee, David; Cunningham, Colin R


    Ultrafast laser inscription (ULI) is a rapidly maturing technique which uses focused ultrashort laser pulses to locally modify the refractive index of dielectric materials in three-dimensions (3D). Recently, ULI has been applied to the fabrication of astrophotonic devices such as integrated beam combiners, 3D integrated waveguide fan-outs and multimode-to-single mode convertors (photonic lanterns). Here, we outline our work on applying ULI to the fabrication of volume phase gratings (VPGs) in fused silica and gallium lanthanum sulphide (GLS) glasses. The VPGs we fabricated had a spatial frequency of 333 lines/mm. The optimum fused silica grating was found to exhibit a first order diffraction efficiency of 40 % at 633 nm, but exhibited approximately 40 % integrated scattered light. The optimum GLS grating was found to exhibit a first order diffraction efficiency of 71 % at 633 nm and less than 5 % integrated scattered light. Importantly for future astronomy applications, both gratings survived cooling to 20 K....

  6. Time/Wavelength Fiber Bragg Grating Multiplexing Sensor Array


    A novel time/wavelength-multiplexed fiber Bragg grating sensor array is presented. This type of sensor array has the advantages of more points for multi-point measurement, simple structure and low cost.

  7. Performance of Silicon immersed gratings: Measurement, analysis and modelling

    Rodenhuis, Michiel; Coppens, Tonny H M; Laubert, Phillip P; van Amerongen, Aaldert H


    The use of Immersed Gratings offers advantages for both space- and ground-based spectrographs. As diffraction takes place inside the high-index medium, the optical path difference and angular dispersion are boosted proportionally, thereby allowing a smaller grating area and a smaller spectrometer size. Short-wave infrared (SWIR) spectroscopy is used in space-based monitoring of greenhouse and pollution gases in the Earth atmosphere. On the extremely large telescopes currently under development, mid-infrared high-resolution spectrographs will, among other things, be used to characterize exo-planet atmospheres. At infrared wavelengths, Silicon is transparent. This means that production methods used in the semiconductor industry can be applied to the fabrication of immersed gratings. Using such methods, we have designed and built immersed gratings for both space- and ground-based instruments, examples being the TROPOMI instrument for the European Space Agency Sentinel-5 precursor mission, Sentinel-5 (ESA) and th...

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

    J. W. He


    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.

  9. Analysis of dispersion characteristics of long period fiber grating

    Jain, Vishal; Pawar, Santosh; Kumbhaj, S.; Sen, P. K.


    Present work deals with theoretical analysis of dispersion characteristics of long period fiber grating using straight forward coupled mode theory. Simple analytical solutions are obtained for co propagating core and cladding modes under linear regime. These solutions are used to derive expressions for transmission coefficient (tLPG), phase (ϕL), delay (τρ) and group velocity dispersion (Dρ) for proposed grating structure. Attention is paid to study the delay response of the grating, by varrying physical parameters like incident wavelength and coupling strength of grating. Negative values of group delay for certain value of coupling strength shows that long period fiber can be used as dispersion compansator device in optical fiber communication link.

  10. Folded cavity angled-grating broad-area lasers.

    Zhao, Yunsong; Zhu, Lin


    The angled-grating broad-area laser is a promising candidate for high power, high brightness diode laser source. The key point in the design is the angled gratings which can simultaneously support the unique snake-like zigzag lasing mode and eliminate the direct Fabry-Perot (FP) feedback. Unlike a conventional laser waveguide mode, the phase front of the zigzag mode periodically changes along the propagation direction. By use of the mirror symmetry of the zigzag mode, we propose and demonstrate the folded cavity angled-grating broad-area lasers. One benefit of this design is to reduce the required wafer space compared to a regular angled-grating broad-area laser, especially in a long cavity laser for high power operation. Experimental results show that the folded cavity laser exhibits good beam quality in far field with a slightly larger threshold and smaller slope efficiency due to the additional interface loss.

  11. Damage behaviors of fiber Bragg grating sensor in fabrication

    Tang, Liqun; Sang, Dengfeng; Chen, Jinming; Yang, Bao; Liu, Yiping


    It is has been noted that for fiber Bragg grating sensor (FBGS), the tensile strengths of fiber Bragg grating sensors (FBGSs) were decreased after the gratings were written, which may reduce the sensor's measurement range obviously. In this paper, we focused on the damage behaviours of FBGS after fabrication experimentally. Firstly, the tensile tests were carried to measure the tensile strengths of naked optical fiber, decoated optical fiber and optical fiber with Bragg gratings to learn deduction of the tensile strength of optical fiber in the cases respectively. Further, the microscope photography was used to observe the surfaces of optical fiber with or without exposure of excimer laser. The main conclusion is that the UV pulse is the main contribution to reduce the strength remarkably, and the mechanical decoating method also can induce the surface damage on the optical fiber.

  12. Simultaneous 2D Strain Sensing Using Polymer Planar Bragg Gratings

    Manuel Rosenberger


    Full Text Available We demonstrate the application of polymer planar Bragg gratings for multi-axial strain sensing and particularly highlight simultaneous 2D strain measurement. A polymer planar Bragg grating (PPBG fabricated with a single writing step in bulk polymethylmethacrylate is used for measuring both tensile and compressive strain at various angles. It is shown that the sensitivity of the PPBG strongly depends on the angle between the optical waveguide into which the grating is inscribed and the direction along which the mechanical load is applied. Additionally, a 2D PPBG fabricated by writing two Bragg gratings angularly displaced from each other into a single polymer platelet is bonded to a stainless steel plate. The two reflected wavelengths exhibit different sensitivities while tested toward tensile and compressive strain. These characteristics make 2D PPBG suitable for measuring multi-axial tensile and compressive strain.

  13. Grating geophone signal processing based on wavelet transform

    Li, Shuqing; Zhang, Huan; Tao, Zhifei


    Grating digital geophone is designed based on grating measurement technique benefiting averaging-error effect and wide dynamic range to improve weak signal detected precision. This paper introduced the principle of grating digital geophone and its post signal processing system. The signal acquisition circuit use Atmega 32 chip as core part and display the waveform on the Labwindows through the RS232 data link. Wavelet transform is adopted this paper to filter the grating digital geophone' output signal since the signal is unstable. This data processing method is compared with the FIR filter that widespread use in current domestic. The result indicates that the wavelet algorithm has more advantages and the SNR of seismic signal improve obviously.

  14. Broadband back grating design for thin film solar cells

    Janjua, Bilal


    In this paper, design based on tapered circular grating structure was studied, to provide broadband enhancement in thin film amorphous silicon solar cells. In comparison to planar structure an absorption enhancement of ~ 7% was realized.

  15. Reduction of Bragg-grating-induced coupling to cladding modes

    Berendt, Martin Ole; Bjarklev, Anders Overgaard; Soccolich, C.E.


    We discuss fiber designs that have been suggested for the reduction of Bragg-grating induced coupling to cladding modes. The discussion is based on a theoretical approach that includes the effect of asymmetry in the UV-induced index grating, made by UV-side writing. Experimental results from...... gratings in a depressed-cladding fiber are compared with simulations. The model gives good agreement with the measured transmission spectrum and accounts for the pronounced coupling to asymmetrical cladding modes, even when the grating is written with the smallest possible blaze. The asymmetry causing...... this is accounted for by the unavoidable attenuation of the UV light. It is found for the considered fiber designs that a high numerical-aperture fiber increases the spectral separation between the Bragg resonance and the onset of cladding-mode losses. A depressed-cladding fiber reduces the coupling strength...

  16. Coherently controlling Raman-induced grating in atomic media

    Arkhipkin, V G; Timofeev, I V


    We consider dynamically controllable periodic structures, called Raman induced gratings, in three- and four-level atomic media, resulting from Raman interaction in a standing-wave pump. These gratings are due to periodic spatial modulation of the Raman nonlinearity and fundamentally differ from the ones based on electromagnetically induced transparency. The transmission and reflection spectra of such gratings can be simultaneously amplified and controlled by varying the pump field intensity. It is shown that a transparent medium with periodic spatial modulation of the Raman gain can be opaque near the Raman resonance and yet at the same time it can be a non-linear amplifying mirror. We also show that spectral properties of the Raman induced grating can be controlled with the help of an additional weak control field.

  17. Modeling of microelectromechanical systems deformable mirror diffraction grating

    Sirbu, Dan; Pluzhnik, Eugene; Belikov, Ruslan


    Model-based wavefront control methods such as electric field conjugation require accurate optical propagation models to create high-contrast regions in the focal plane using deformable mirrors (DMs). Recently, it has been shown that it is possible to exceed the controllable outer-working angle imposed by the Nyquist limit based on the number of actuators by utilizing a diffraction grating. The print-through pattern on MEMS-based DMs formed during the fabrication process creates both an amplitude and a phase diffraction grating that can be used to enable Super-Nyquist wavefront control. Using interferometric measurements of a DM-actuator, we develop a DM-diffraction grating model. We compare the total energy enclosed in the first diffraction order due to the phase, amplitude, and combined phase-amplitude gratings with laboratory measurements.

  18. Photonic crystal fiber long-period gratings for biochemical sensing.

    Rindorf, Lars; Jensen, Jesper B; Dufva, Martin; Pedersen, Lars Hagsholm; Høiby, Poul Erik; Bang, Ole


    We present experimental results showing that long-period gratings in photonic crystal fibers can be used as sensitive biochemical sensors. A layer of biomolecules was immobilized on the sides of the holes of the photonic crystal fiber and by observing the shift in the resonant wavelength of a long-period grating it was possible to measure the thickness of the layer. The long-period gratings were inscribed in a large-mode area silica photonic crystal fiber with a CO2 laser. The thicknesses of a monolayer of poly-L-lysine and double-stranded DNA was measured using the device. We find that the grating has a sensitivity of approximately 1.4nm/1nm in terms of the shift in resonance wavelength in nm per nm thickness of biomolecule layer.

  19. Structural Health Monitoring Using Fiber Bragg Grating Sensor Matrix Project

    National Aeronautics and Space Administration — Fiber Bragg Grating had been identified as very important elements, especially for strain measurements in smart structures. In many applications, arrays of FBG...

  20. Cartographic Relief Presentation Revisited - Forty Years after Eduard Imhof

    Hurni, Lorenz

    Topographic maps represent in a symbolised way the main features of the Earth's surface shape as well as the major, mostly visible objects covering the topography. The clear and readable depiction of the relief is one of the main challenges in topographic cartography. The Swiss cartographer Eduard Imhof had a significant influence on the development of modern topographic cartography. He published his trend-setting findings 40 years ago in his textbook "Cartographic Relief Presentation". This overview paper reviews his major contributions to topographic cartography and presents today's state of cartographic relief depiction, illustrated by current map examples and projects elaborated at Imhof's Alma Mater, the Institute of Cartography of ETH Zurich.


    S. G. Pugacheva


    Full Text Available In article the basic geological and morphological features of a volcanic relief of a surface of a planet Mars are considered. The volcanic relief of a planet represents relic ancient shield volcanoes, linear forms of volcanic mountains, areal and central lava flooding, radial and concentric breaks. Results of researches of morphology of volcanic and tectonic formations of a relief of Mars are given in article. On materials of shooting of a surface of Mars spacecrafts constructed hypsometric high-rise profiles of volcanoes and average steepness of slopes are defined. The relative age of volcanoes and volcanic plains is estimated on density of shock craters.

  2. Rapidly design safety relief valve inlet piping systems

    Westman, M.A.


    Safety relief valves (SRVs) used to protect against overpressure require well-designed inlet piping for proper operation. The engineer`s job is to produce these designs from a thorough understanding of the inlet piping as a key component in the safety relief system and the correct application of the governing fluid dynamics principles. This article will present a technique for analysis and design using classical ideal-gas adiabatic fluid flow principles. Also, it will discuss the advantages of using the personal computer (PC) to quickly arrive at accurate designs. This work applies to SRVs in which relief flows are limited by sonic conditions at their nozzles.

  3. Diffraction grating characterisation for cold-atom experiments

    McGilligan, James P; Riis, Erling; Arnold, Aidan S


    We have studied the optical properties of gratings micro-fabricated into semiconductor wafers, which can be used for simplifying cold-atom experiments. The study entailed characterisation of diffraction efficiency as a function of coating, periodicity, duty cycle and geometry using over 100 distinct gratings. The critical parameters of experimental use, such as diffraction angle and wavelength are also discussed, with an outlook to achieving optimal ultracold experimental conditions.

  4. Nonlinear pulse propagation in birefringent fiber Bragg gratings.

    Pereira, S; Sipe, J


    We present two sets of equations to describe nonlinear pulse propagation in a birefringent fiber Bragg grating. The first set uses a coupled-mode formalism to describe light in or near the photonic band gap of the grating. The second set is a pair of coupled nonlinear Schroedinger equations. We use these equations to examine viable switching experiments in the presence of birefringence. We show how the birefringence can both aid and hinder device applications.

  5. Relativistic surface-plasmon enhanced harmonic generation from gratings

    Fedeli, Luca; Cantono, Giada; Macchi, Andrea


    The role of relativistic surface plasmons (SPs) in high order harmonic emission from laser-irradiated grating targets has been investigated by means of particle-in-cell simulations. SP excitation drives a strong enhancement of the intensity of harmonics, particularly in the direction close to the surface tangent. The SP-driven enhancement overlaps with the angular separation of harmonics generated by the grating, which is beneficial for applications requiring monochromatic XUV pulses.

  6. Zeonex Microstructured Polymer Optical Fibre Bragg Grating Sensor

    Woyessa, Getinet; Fasano, Andrea; Markos, Christos


    We fabricated an endlessly single mode and humidity insensitive Zeonex microstructured polymer optical fibre (mPOF) for fibre Bragg grating (FBG) temperature and strain sensors. We inscribed and characterise FBGs in Zeonex mPOF for the first time.......We fabricated an endlessly single mode and humidity insensitive Zeonex microstructured polymer optical fibre (mPOF) for fibre Bragg grating (FBG) temperature and strain sensors. We inscribed and characterise FBGs in Zeonex mPOF for the first time....

  7. Moiré Fibre Bragg Grating Written on Strained Fibres

    孙磊; 冯新焕; 刘艳格; 张伟刚; 袁树忠; 开桂云; 董孝义


    Moiré fibre Bragg gratings are made in a single mode fibre and a polarization-maintaining fibre respectively, using an excimer KrF laser and a phase mask. Two gratings are written at the same location of the optical fibre. The wavelength spacing can be finely tuned from 0 to 1.86nm by straining the optical fibre during UV illumination.

  8. Fibre Bragg Grating Components for Filtering, Switching and Lasing


    Fibre Bragg gratings (FBGs) are key components for a vast number of applications in optical communication systems, microwave photonics systems, and optical sensors, etc. The main topic of this thesis is fibre Bragg grating fabrication and applications in direct microwave optical filtering, high speed switching and switchable dual-wavelength fibre lasers. First, a brief overview is given about the photosensitivity in optical fibre, basic FBG fabrication techniques, the popular coupled-mode the...

  9. Guided wave coupling in integrated-optic gratings - Normal incidence

    van Roey, J.; Denturck, B.; Lagasse, P. E.


    The coupling between the different guided modes of an integrated-optic waveguide grating filter is analyzed. A numerical method based on a finite-difference scheme for the solution of this coupling problem in the case of normal incidence is presented. This allows one to study the influence of the grating profile on the coupling between guided or radiated waves. The exact numerical results are compared with approximate formulas for the coupling coefficient.

  10. On the Intensity Distribution Function of Blazed Reflective Diffraction Gratings

    Casini, R.; Nelson, P G


    We derive from first principles the expression for the angular/wavelength distribution of the intensity diffracted by a blazed reflective grating, according to a scalar theory of diffraction. We considered the most common case of a groove profile with rectangular apex. Our derivation correctly identifies the geometric parameters of a blazed reflective grating that determine its diffraction efficiency, and fixes an incorrect but commonly adopted expression in the literature. We compare the pre...

  11. Wave-front-engineered grating mirrors for VCSELs

    Carletti, Luca; Malureanu, Radu; Mørk, Jesper;


    High-index-contrast grating mirrors featuring beam steering abilities for the transmitted beam as well as high reflectivity over a broad bandwidth are suggested. Gratings designed to provide control over the wave front of the transmitted beam are numerically investigated. The proposed structures ...... mirrors would have a significant impact on low cost laser sources fabrication, since a more efficient integration of optoelectronic modules can be achieved by avoiding expensive external lens systems....

  12. Grating-assisted silicon-on-insulator racetrack resonator reflector.

    Boeck, Robert; Caverley, Michael; Chrostowski, Lukas; Jaeger, Nicolas A F


    We experimentally demonstrate a grating-assisted silicon-on-insulator (SOI) racetrack resonator reflector with a reflect port suppression of 10.3 dB and no free spectral range. We use contra-directional grating couplers within the coupling regions of the racetrack resonator to enable suppression of all but one of the peaks within the reflect port spectrum as well as all but one of the notches within the through port spectrum.

  13. Coupling between counterpropagating cladding modes in fiber Bragg gratings.

    Sáez-Rodriguez, D; Cruz, J L; Díez, A; Andrés, M V


    We present an experimental demonstration of energy transfer between counterpropagating cladding modes in a fiber Bragg grating (FBG). A strong FBG written in a standard photosensitive optical fiber is illuminated with a single cladding mode, and the power transferred between the forward propagating cladding mode and different backward propagating cladding modes is measured by using two auxiliary long period gratings. Resonances between cladding modes having 30 pm bandwidth and 8 dB rejection have been observed.

  14. Periodically patterned columnar thin films as Blazed gratings

    Dutta, Jhuma; Lakhtakia, Akhlesh


    Periodically patterned columnar thin films (PP-CTFs) were made by evaporating CaF2 and directing the vapor flux obliquely towards lithographically fabricated micrometer/sub-micrometer gratings. The growth of the PP-CTFs was controlled by the deposition rate to form prismatic air cavities within them and they function like blazed diffraction gratings with asymmetric diffraction patterns and diffraction efficiencies upto 52% in transmission at visible wavelengths. Scalar diffraction theory qualitatively explained the measured diffraction efficiencies.

  15. Refraction effects in soft x-ray multilayer blazed gratings.

    Voronov, D L; Salmassi, F; Meyer-Ilse, J; Gullikson, E M; Warwick, T; Padmore, H A


    A 2500 lines/mm Multilayer Blazed Grating (MBG) optimized for the soft x-ray wavelength range was fabricated and tested. The grating coated with a W/B4C multilayer demonstrated a record diffraction efficiency in the 2nd blazed diffraction order in the energy range from 500 to 1200 eV. Detailed investigation of the diffraction properties of the grating demonstrated that the diffraction efficiency of high groove density MBGs is not limited by the normal shadowing effects that limits grazing incidence x-ray grating performance. Refraction effects inherent in asymmetrical Bragg diffraction were experimentally confirmed for MBGs. The refraction affects the blazing properties of the MBGs and results in a shift of the resonance wavelength of the gratings and broadening or narrowing of the grating bandwidth depending on diffraction geometry. The true blaze angle of the MBGs is defined by both the real structure of the multilayer stack and by asymmetrical refraction effects. Refraction effects can be used as a powerful tool in providing highly efficient suppression of high order harmonics.

  16. Fourier optics analysis of grating sensors with tilt errors.

    Ferhanoglu, Onur; Toy, M Fatih; Urey, Hakan


    Dynamic diffraction gratings can be microfabricated with precision and offer extremely sensitive displacement measurements and light intensity modulation. The effect of pure translation of the moving part of the grating on diffracted order intensities is well known. This study focuses on the parameters that limit the intensity and the contrast of the interference. The effects of grating duty cycle, mirror reflectivities, sensor tilt and detector size are investigated using Fourier optics theory and Gaussian beam optics. Analytical findings reveal that fringe visibility becomes <0.3 when the optical path variation exceeds half the wavelength within the grating interferometer. The fringe visibility can be compensated by monitoring the interfering portion of the diffracted order light only through detector size reduction in the expense of optical power. Experiments were conducted with a grating interferometer that resulted in an eightfold increase in fringe visibility with reduced detector size, which is in agreement with theory. Findings show that diffraction grating readout principle is not limited to translating sensors but also can be used for sensors with tilt or other deflection modes.

  17. MEMS-based tunable gratings and their applications

    Yu, Yiting; Yuan, Weizheng; Qiao, Dayong


    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.

  18. Slow light in fiber Bragg gratings and its applications

    Skolianos, George; Arora, Arushi; Bernier, Martin; Digonnet, Michel


    Slow-light fiber Bragg gratings (FBGs) belong to a class of gratings designed to exhibit one or more narrow resonances in their reflection and transmission spectra, produced either by introducing a π phase shift near the middle of the grating, or by increasing the index modulation so that the grating behaves like a Fabry-Perot interferometer. These resonances can have very narrow linewidths (optics, optical switching, optical delay lines, and sensing. This paper reviews the principle of these gratings, in particular the more recent slow-light gratings relying on a strong index modulation. It discusses in particular the requirements for achieving large group delays and high sensitivities in sensors, and the fabrication and annealing techniques used to meet these requirements (high index modulation, low loss, index-profile apodization, and optimized length). Several applications are presented, including record-breaking FBGs that exhibit a group delay of 42 ns and Q-factor of ~30 million over a 12.5 mm length, robust acoustic sensors with pressure resolution of ~50 µPa (√Hz)-1 in the few-kHz, and a strain sensor capable of resolving as little as 30 femtostrain (√Hz)-1.

  19. Apodized grating coupler using fully-etched nanostructures

    Wu, Hua; Li, Chong; Li, Zhi-Yong; Guo, Xia


    A two-dimensional apodized grating coupler for interfacing between single-mode fiber and photonic circuit is demonstrated in order to bridge the mode gap between the grating coupler and optical fiber. The grating grooves of the grating couplers are realized by columns of fully etched nanostructures, which are utilized to digitally tailor the effective refractive index of each groove in order to obtain the Gaussian-like output diffractive mode and then enhance the coupling efficiency. Compared with that of the uniform grating coupler, the coupling efficiency of the apodized grating coupler is increased by 4.3% and 5.7%, respectively, for the nanoholes and nanorectangles as refractive index tunes layer. Project supported by the National Natural Science Foundation of China (Grant Nos. 61222501, 61335004, and 61505003), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20111103110019), the Postdoctoral Science Foundation of Beijing Funded Project, China (Grant No. Q6002012201502), and the Science and Technology Research Project of Jiangxi Provincial Education Department, China (Grant No. GJJ150998).

  20. Improved optical enhancement in binary plasmonic gratings with nanogap spacing

    Darweesh, Ahmad A.; Bauman, Stephen J.; Brawley, Zachary T.; Herzog, Joseph B.


    This work thoroughly investigates binary nanowire gratings with nanogap spacing. A binary plasmonic grating is a periodic nanostructure for which each period has two different widths. The study has determined that plasmonic gratings with two different widths in each period give rise to optical enhancement that is 2.1 times stronger than that of standard plasmonic grating structures. A map of varying width ratios has been created to illustrate the key geometric characteristic for enhancement optimization. The structure under investigation was a gold structure with a constant height of 15 nm and a nanogap of 5 nm. The period size of the structure depends on the two nanowire widths in each grating period. The optical enhancement (E/E0)2 of the geometry was investigated using a finite element method (FEM) simulation for various wavelengths. The results show a strong correlation between the plasmon wavelength and the periodicity of the gratings. Additionally, the plasmonic charge distributions have been calculated for various periods and geometries. Various resonant modes exist for the charge distribution, significantly affecting the enhancement depending on the nanowire widths.

  1. Numerical Analysis of Fiber Bragg Grating and Long Period Fiber Grating Undergoing Linear and Quadratic Temperature Change

    YUAN Yinquan; DING Liyun


    The coupled-mode equations for fiber Bragg grating(FBG)and long period fiber grating(LPFG)undergoing linear and quadratic temperature change were given.The effects of tem-perature gradient and quadratic temperature change on the reflectivity spectrum of fiber Braggs grating and the transmission spectrum of long period fiber grating were investigated using the numerical simulation,and the dependence relationships of the central wavelength shift,the full-width-at-half-maximum,and the peak intensity upon temperature gradient were also obtained.These relation-ships may be used to design a novel fiber optical sensor which can simultaneously measure the tem-perature and temperature gradient.

  2. Design of a variable-line-spacing grating pattern for spectrometers based on a grating Fresnel device.

    Li, Xinghui; Zhang, Jinchao; Zhou, Qian; Ni, Kai; Pang, Jinchao; Tian, Rui


    In this Letter, we propose a variable-line-spacing (VLS) grating pattern for a hybrid diffractive device termed a grating Fresnel (G-Fresnel) lens, which is used in spectrometers to improve spectral resolution over a wide spectral range. The VLS grating pattern disperses light of specific wavelengths with a different angle and position such that the aberration caused by the Fresnel surface can be compensated for. In this manner, high resolution can be achieved over a relatively wide spectral range. The VLS grating pattern is designed based on the least wave-change principle and simulated by ZEMAX. Results reveal that the VLS G-Fresnel device allows a subnanometer resolution over a spectral range of 200 nm.

  3. Fiber optic hot-wire flowmeter based on a metallic coated hybrid long period grating/fiber Bragg grating structure.

    Caldas, Paulo; Jorge, Pedro A S; Rego, Gaspar; Frazão, Orlando; Santos, José Luís; Ferreira, Luís Alberto; Araújo, Francisco


    In this work an all-optical hot-wire flowmeter based on a silver coated fiber combining a long period grating and a fiber Bragg grating (FBG) structure is proposed. Light from a pump laser at 1480  nm propagating down the fiber is coupled by the long period grating into the fiber cladding and is absorbed by the silver coating deposited on the fiber surface over the Bragg grating structure. This absorption acts like a hot wire raising the fiber temperature locally, which is effectively detected by the FBG resonance shift. The temperature increase depends on the flow speed of the surrounding air, which has the effect of cooling the fiber. It is demonstrated that the Bragg wavelength shift can be related to the flow speed. A flow speed resolution of 0.08  m/s is achieved using this new configuration.

  4. Targeting the cannabinoid system for pain relief?

    Chiou, Lih-Chu; Hu, Sherry Shu-Jung; Ho, Yu-Cheng


    Marijuana has been used to relieve pain for centuries, but its analgesic mechanism has only been understood during the past two decades. It is mainly mediated by its constituents, cannabinoids, through activating central cannabinoid 1 (CB1) receptors, as well as peripheral CB1 and CB2 receptors. CB2-selective agonists have the benefit of lacking CB1 receptor-mediated CNS side effects. Anandamide and 2-arachidonoylglycerol (2-AG) are two intensively studied endogenous lipid ligands of cannabinoid receptors, termed endocannabinoids, which are synthesized on demand and rapidly degraded. Thus, inhibitors of their degradation enzymes, fatty acid amide hydrolase and monoacylglycerol lipase (MAGL), respectively, may be superior to direct cannabinoid receptor ligands as a promising strategy for pain relief. In addition to the antinociceptive properties of exogenous cannabinoids and endocannabinoids, involving their biosynthesis and degradation processes, we also review recent studies that revealed a novel analgesic mechanism, involving 2-AG in the periaqueductal gray (PAG), a midbrain region for initiating descending pain inhibition. It is initiated by Gq-protein-coupled receptor (GqPCR) activation of the phospholipase C (PLC)-diacylglycerol lipase (DAGL) enzymatic cascade, generating 2-AG that produces inhibition of GABAergic transmission (disinhibition) in the PAG, thereby leading to analgesia. This GqPCR-PLC-DAGL-2-AG retrograde disinhibition mechanism in the PAG can be initiated by activating type 5 metabotropic glutamate receptor (mGluR5), muscarinic acetylcholine (M1/M3), and orexin (OX1) receptors. mGluR5-mediated disinhibition can be initiated by glutamate transporter inhibitors, or indirectly by substance P, neurotensin, cholecystokinin, capsaicin, and AM404, the bioactive metabolite of acetaminophen in the brain. The putative role of 2-AG generated after activating the above neurotransmitter receptors in stress-induced analgesia is also discussed.

  5. Dynamic high pressure measurements using a Fiber Bragg Grating probe and an arrayed waveguide grating spectrometer

    Barbarin, Y.; Lefrançois, A.; Magne, S.; Woirin, K.; Sinatti, F.; Osmont, A.; Luc, J.


    High pressure shock profiles are monitored using a long Fiber Bragg Grating (FBG). Such thin probe, with a diameter of typically 150 μm, can be inserted directly into targets for shock plate experiments. The shocked FBG's portion is stressed under compression, which increases its optical group index and shortens its grating period. Placed along the 2D symmetrical axis of the cylindrical target, the second effect is stronger and the reflected spectrum shifts towards the shorter wavelengths. The dynamic evolution of FBG spectra is recorded with a customized Arrayed Waveguide Grating (AWG) spectrometer covering the C+L band. The AWG provides 40 channels of 200-GHz spacing with a special flattop design. The output channels are fiber-connected to photoreceivers (bandwidth: DC - 400 MHz or 10 kHz - 2 GHz). The experimental setup was a symmetric impact, completed in a 110-mm diameter single-stage gas gun with Aluminum (6061T6) impactors and targets. The FBG's central wavelength was 1605 nm to cover the pressure range of 0 - 8 GPa. The FBG was 50-mm long as well as the target's thickness. The 20-mm thick impactor maintains a shock within the target over a distance of 30 mm. For the impact at 522 m/s, the sustained pressure of 3.6 GPa, which resulted in a Bragg shift of (26.2 +/- 1.5) nm, is measured and retrieved with respectively thin-film gauges and the hydrodynamic code Ouranos. The shock sensitivity of the FBG is about 7 nm/GPa, but it decreases with the pressure level. The overall spectra evolution is in good agreement with the numerical simulations.

  6. Feasibility of Fiber Bragg Grating and Long-Period Fiber Grating Sensors under Different Environmental Conditions

    Jian-Neng Wang


    Full Text Available This paper presents the feasibility of utilizing fiber Bragg grating (FBG and long-period fiber grating (LPFG sensors for nondestructive evaluation (NDE of infrastructures using Portland cement concretes and asphalt mixtures for temperature, strain, and liquid-level monitoring. The use of hybrid FBG and LPFG sensors is aimed at utilizing the advantages of two kinds of fiber grating to implement NDE for monitoring strains or displacements, temperatures, and water-levels of infrastructures such as bridges, pavements, or reservoirs for under different environmental conditions. Temperature fluctuation and stability tests were examined using FBG and LPFG sensors bonded on the surface of asphalt and concrete specimens. Random walk coefficient (RWC and bias stability (BS were used for the first time to indicate the stability performance of fiber grating sensors. The random walk coefficients of temperature variations between FBG (or LPFG sensor and a thermocouple were found in the range of −0.7499 °C/ to −1.3548 °C/. In addition, the bias stability for temperature variations, during the fluctuation and stability tests with FBG (or LPFG sensors were within the range of 0.01 °C/h with a 15–18 h time cluster to 0.09 °C/h with a 3–4 h time cluster. This shows that the performance of FBG or LPFG sensors is comparable with that of conventional high-resolution thermocouple sensors under rugged conditions. The strain measurement for infrastructure materials was conducted using a packaged FBG sensor bonded on the surface of an asphalt specimen under indirect tensile loading conditions. A finite element modeling (FEM was applied to compare experimental results of indirect tensile FBG strain measurements. For a comparative analysis between experiment and simulation, the FEM numerical results agreed with those from FBG strain measurements. The results of the liquid-level sensing tests show the LPFG-based sensor could discriminate five stationary liquid

  7. Grayscale North America Shaded Relief ? 1-Kilometer Resolution - Direct Download

    U.S. Geological Survey, Department of the Interior — The grayscale North America shaded relief data were derived from the GTOPO30 elevation data. GTOPO30 is a global digital elevation model (DEM) with a horizontal grid...

  8. U.S. Coastal Relief Model - Western Gulf of Mexico

    National Oceanic and Atmospheric Administration, Department of Commerce — NGDC's U.S. Coastal Relief Model (CRM) provides the first comprehensive view of the U.S. coastal zone integrating offshore bathymetry with land topography into a...

  9. U.S. Coastal Relief Model - Puerto Rico

    National Oceanic and Atmospheric Administration, Department of Commerce — NGDC's U.S. Coastal Relief Model (CRM) provides the first comprehensive view of the U.S. coastal zone integrating offshore bathymetry with land topography into a...

  10. U.S. Coastal Relief Model - Central Gulf of Mexico

    National Oceanic and Atmospheric Administration, Department of Commerce — NGDC's U.S. Coastal Relief Model (CRM) provides the first comprehensive view of the U.S. coastal zone integrating offshore bathymetry with land topography into a...

  11. U.S. Coastal Relief Model - Southern California Version 2

    National Oceanic and Atmospheric Administration, Department of Commerce — NGDC's U.S. Coastal Relief Model (CRM) provides a comprehensive view of the U.S. coastal zone integrating offshore bathymetry with land topography into a seamless...

  12. Anti-Seizure Medications: Relief from Nerve Pain

    Anti-seizure medications: Relief from nerve pain Anti-seizure drugs often are used to help control the type of ... by damaged nerves. By Mayo Clinic Staff Anti-seizure medications were originally designed to treat people with ...

  13. Color Hawaii Shaded Relief ? 200-Meter Resolution - Direct Download

    U.S. Geological Survey, Department of the Interior — The color Hawaii shaded relief data were derived from National Elevation Dataset (NED) data, and show the terrain of Hawaii at a resolution of 200 meters. The NED is...

  14. Satellite View of Hawaii, with Shaded Relief - Direct Download

    U.S. Geological Survey, Department of the Interior — The Satellite View of Hawaii, with Shaded Relief map layer is a 200- meter-resolution simulated-natural-color image of Hawaii. Vegetation is generally green, with...

  15. Satellite View of Alaska, with Shaded Relief - Direct Download

    U.S. Geological Survey, Department of the Interior — The Satellite View of Alaska, with Shaded Relief map layer is a 200- meter-resolution simulated-natural-color image of Alaska. Vegetation is generally green, with...

  16. The development of safety relief valve for nuclear service

    Kim, Chil Sung; Kim, Kang Tae; Kim, Ji Heon; Jang, Ki Jong [Smart Valve Com., Seoul (Korea, Republic of); Hong, Kee Seong [Korea Hydro and Nuclear Power Co., Ltd., Seoul (Korea, Republic of)


    Safety relief valve is the important equipment used to protect the pressure facility from overpressure. The objective of the study is the development of safety relief valve which protects the boiler and pressure vessel from over pressure by discharging or sucking the operating medium when the pressure of system is reaching the set pressure of the system. It is important to find out the relationship between trim shape and performance, so the characteristics of flow field at the inside of safety relief valve were investigated through computational fluid dynamics analysis. The study shows that safety relief valve is developed though the design using the analysis between flow characteristics and spring force, the experiential verification.

  17. U.S. Coastal Relief Model - Southeast Atlantic

    National Oceanic and Atmospheric Administration, Department of Commerce — NGDC's U.S. Coastal Relief Model (CRM) provides the first comprehensive view of the U.S. coastal zone integrating offshore bathymetry with land topography into a...

  18. U.S. Coastal Relief Model - Northwest Pacific

    National Oceanic and Atmospheric Administration, Department of Commerce — NGDC's U.S. Coastal Relief Model (CRM) provides the first comprehensive view of the U.S. coastal zone integrating offshore bathymetry with land topography into a...

  19. U.S. Coastal Relief Model - Northeast Atlantic

    National Oceanic and Atmospheric Administration, Department of Commerce — NGDC's U.S. Coastal Relief Model (CRM) provides the first comprehensive view of the U.S. coastal zone integrating offshore bathymetry with land topography into a...

  20. U.S. Coastal Relief Model - Southern California

    National Oceanic and Atmospheric Administration, Department of Commerce — NGDC's U.S. Coastal Relief Model (CRM) provides the first comprehensive view of the U.S. coastal zone integrating offshore bathymetry with land topography into a...