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Sample records for absorbing optical materials

  1. Optical response of strongly absorbing inhomogeneous materials: Application to paper degradation

    NASA Astrophysics Data System (ADS)

    Missori, M.; Pulci, O.; Teodonio, L.; Violante, C.; Kupchak, I.; Bagniuk, J.; Łojewska, J.; Conte, A. Mosca

    2014-02-01

    In this paper, we present a new noninvasive and nondestructive approach to recover scattering and absorption coefficients from reflectance measurements of highly absorbing and optically inhomogeneous media. Our approach is based on the Yang and Miklavcic theoretical model of light propagation through turbid media, which is a generalization of the Kubelka-Munk theory, extended to accommodate optically thick samples. We show its applications to paper, a material primarily composed of a web of fibers of cellulose, whose optical properties are strongly governed by light scattering effects. Samples studied were ancient and industrial paper sheets, aged in different conditions and highly absorbing in the ultraviolet region. The recovered experimental absorptions of cellulose fibers have been compared to theoretical ab initio quantum-mechanical computational simulations carried out within time-dependent density functional theory. In this way, for each sample, we evaluate the absolute concentration of different kinds of oxidized groups formed upon aging and acting as chromophores causing paper discoloration. We found that the relative concentration of different chromophores in cellulose fibers depends on the aging temperature endured by samples. This clearly indicates that the oxidation of cellulose follows temperature-dependent reaction pathways. Our approach has a wide range of applications for cellulose-based materials, like paper, textiles, and other manufactured products of great industrial and cultural interest, and can potentially be extended to other strongly absorbing inhomogeneous materials.

  2. Advanced neutron absorber materials

    DOEpatents

    Branagan, Daniel J.; Smolik, Galen R.

    2000-01-01

    A neutron absorbing material and method utilizing rare earth elements such as gadolinium, europium and samarium to form metallic glasses and/or noble base nano/microcrystalline materials, the neutron absorbing material having a combination of superior neutron capture cross sections coupled with enhanced resistance to corrosion, oxidation and leaching.

  3. Solar radiation absorbing material

    DOEpatents

    Googin, John M.; Schmitt, Charles R.; Schreyer, James M.; Whitehead, Harlan D.

    1977-01-01

    Solar energy absorbing means in solar collectors are provided by a solar selective carbon surface. A solar selective carbon surface is a microporous carbon surface having pores within the range of 0.2 to 2 micrometers. Such a surface is provided in a microporous carbon article by controlling the pore size. A thermally conductive substrate is provided with a solar selective surface by adhering an array of carbon particles in a suitable binder to the substrate, a majority of said particles having diameters within the range of about 0.2-10 microns.

  4. Two-photon or higher-order absorbing optical materials and methods of use

    NASA Technical Reports Server (NTRS)

    Marder, Seth (Inventor); Perry, Joseph (Inventor)

    2001-01-01

    Compositions capable of simultaneous two-photon absorption and higher order absorptivities are disclosed. Many of these compositions are compounds satisfying the formulae D-.PI.-D, A-.PI.-A, D-A-D and A-D-A, wherein D is an electron donor group, A is an electron acceptor group and .PI. comprises a bridge of .pi.-conjugated bonds connecting the electron donor groups and electron acceptor groups. In A-D-A and D-A-D compounds, the .pi. bridge is substituted with electron donor groups and electron acceptor groups, respectively. Also disclosed are methods that generate an electronically excited state of a compound, including those satisfying one of these formulae. The electronically excited state is achieved in a method that includes irradiating the compound with light. Then, the compound is converted to a multi-photon electronically excited state upon simultaneous absorption of at least two photons of light. The sum of the energies of all of the absorbed photons is greater than or equal to the transition energy from a ground state of the compound to the multi-photon excited state. The energy of each absorbed photon is less than the transition energy between the ground state and the lowest single-photon excited state of the compound is less than the transition energy between the multi-photon excited state and the ground state.

  5. Two-photon or higher-order absorbing optical materials for generation of reactive species

    NASA Technical Reports Server (NTRS)

    Cumpston, Brian (Inventor); Lipson, Matthew (Inventor); Marder, Seth R (Inventor); Perry, Joseph W (Inventor)

    2007-01-01

    Disclosed are highly efficient multiphoton absorbing compounds and methods of their use. The compounds generally include a bridge of pi-conjugated bonds connecting electron donating groups or electron accepting groups. The bridge may be substituted with a variety of substituents as well. Solubility, lipophilicity, absorption maxima and other characteristics of the compounds may be tailored by changing the electron donating groups or electron accepting groups, the substituents attached to or the length of the pi-conjugated bridge. Numerous photophysical and photochemical methods are enabled by converting these compounds to electronically excited states upon simultaneous absorption of at least two photons of radiation. The compounds have large two-photon or higher-order absorptivities such that upon absorption, one or more Lewis acidic species, Lewis basic species, radical species or ionic species are formed.

  6. Two-Photon or Higher-Order Absorbing Optical Materials for Generation of Reactive Species

    NASA Technical Reports Server (NTRS)

    Cumpston, Brian (Inventor); Lipson, Matthew (Inventor); Marder, Seth R. (Inventor); Perry, Joseph W. (Inventor)

    2013-01-01

    Disclosed are highly efficient multiphoton absorbing compounds and methods of their use. The compounds generally include a bridge of pi-conjugated bonds connecting electron donating groups or electron accepting groups. The bridge may be substituted with a variety of substituents as well. Solubility, lipophilicity, absorption maxima and other characteristics of the compounds may be tailored by changing the electron donating groups or electron accepting groups, the substituents attached to or the length of the pi-conjugated bridge. Numerous photophysical and photochemical methods are enabled by converting these compounds to electronically excited states upon simultaneous absorption of at least two photons of radiation. The compounds have large two-photon or higher-order absorptivities such that upon absorption, one or more Lewis acidic species, Lewis basic species, radical species or ionic species are formed.

  7. Two-photon or higher-order absorbing optical materials for generation of reactive species

    NASA Technical Reports Server (NTRS)

    Cumpston, Brian (Inventor); Lipson, Matthew (Inventor); Marder, Seth R. (Inventor); Perry, Joseph W. (Inventor)

    2003-01-01

    Disclosed are highly efficient multiphoton absorbing compounds and methods of their use. The compounds generally include a bridge of pi-conjugated bonds connecting electron donating groups or electron accepting groups. The bridge may be substituted with a variety of substituents as well. Solubility, lipophilicity, absorption maxima and other characteristics of the compounds may be tailored by changing the electron donating groups or electron accepting groups, the substituents attached to or the length of the pi-conjugated bridge. Numerous photophysical and photochemical methods are enabled by converting these compounds to electronically excited states upon simultaneous absorption of at least two photons of radiation. The compounds have large two-photon or higher-order absorptivities such that upon absorption, one or more Lewis acidic species, Lewis basic species, radical species or ionic species are formed.

  8. Two-photon or higher-order absorbing optical materials and methods of use

    NASA Technical Reports Server (NTRS)

    Marder, Seth (Inventor); Perry, Joseph (Inventor)

    2012-01-01

    Compositions capable of simultaneous two-photon absorption and higher order absorptivities are provided. Compounds having a donor-pi-donor or acceptor-pi-acceptor structure are of particular interest, where the donor is an electron donating group, acceptor is an electron accepting group, and pi is a pi bridge linking the donor and/or acceptor groups. The pi bridge may additionally be substituted with electron donating or withdrawing groups to alter the absorptive wavelength of the structure. Also disclosed are methods of generating an excited state of such compounds through optical stimulation with light using simultaneous absorption of photons of energies individually insufficient to achieve an excited state of the compound, but capable of doing so upon simultaneous absorption of two or more such photons. Applications employing such methods are also provided, including controlled polymerization achieved through focusing of the light source(s) used.

  9. Durability of Polymeric Glazing and Absorber Materials

    SciTech Connect

    Jorgensen, G.; Terwilliger, K.; Bingham, C.; Milbourne, M.

    2005-01-01

    The Solar Heating and Lighting Program has set the goal of reducing the cost of solar water heating systems by at least 50%. An attractive approach to such large cost reduction is to replace glass and metal parts with less-expensive, lighter-weight, more-integrated polymeric components. The key challenge with polymers is to maintain performance and assure requisite durability for extended lifetimes. The objective of this task is to quantify lifetimes through measurement of the optical and mechanical stability of candidate polymeric glazing and absorber materials. Polycarbonate sheet glazings, as proposed by two industry partners, have been tested for resistance to UV radiation with three complementary methods. Incorporation of a specific 2-mil thick UV-absorbing screening layer results in glazing lifetimes of at least 15 years; improved screens promise even longer lifetimes. Proposed absorber materials were tested for creep and embrittlement under high temperature, and appear adequate for planned ICS absorbers.

  10. Porcelain enamel neutron absorbing material

    DOEpatents

    Iverson, Daniel C.

    1990-02-06

    A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compounds of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved.

  11. Porcelain enamel neutron absorbing material

    DOEpatents

    Iverson, D.C.

    1987-11-20

    A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compound of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved. 2 figs.

  12. Porcelain enamel neutron absorbing material

    DOEpatents

    Iverson, Daniel C.

    1990-01-01

    A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compounds of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved.

  13. Innovative Solar Optical Materials

    NASA Astrophysics Data System (ADS)

    Lampert, Carl M.

    1984-02-01

    A variety of optical coatings are discussed in the context of solar energy utilization. Well-known coatings such as transparent conductors (heat mirrors), selective absorbers, and reflective films are surveyed briefly. Emphasis is placed on the materials' limitations and on use of lesser-known optical coatings and materials. Physical and optical properties are detailed for protective antireflection films, cold mirrors, fluorescent concentrator materials, radiative cooling surfaces, and optical switching films including electrochromic, thermochromic, photochromic, and liquid crystal types. For many of these materials, research has only recently been considered, so various design and durability issues need to be addressed.

  14. Semiconductor nanowire optical antenna solar absorbers.

    PubMed

    Cao, Linyou; Fan, Pengyu; Vasudev, Alok P; White, Justin S; Yu, Zongfu; Cai, Wenshan; Schuller, Jon A; Fan, Shanhui; Brongersma, Mark L

    2010-02-10

    Photovoltaic (PV) cells can serve as a virtually unlimited clean source of energy by converting sunlight into electrical power. Their importance is reflected in the tireless efforts that have been devoted to improving the electrical and structural properties of PV materials. More recently, photon management (PM) has emerged as a powerful additional means to boost energy conversion efficiencies. Here, we demonstrate an entirely new PM strategy that capitalizes on strong broad band optical antenna effects in one-dimensional semiconductor nanostructures to dramatically enhance absorption of sunlight. We show that the absorption of sunlight in Si nanowires (Si NWs) can be significantly enhanced over the bulk. The NW's optical properties also naturally give rise to an improved angular response. We propose that by patterning the silicon layer in a thin film PV cell into an array of NWs, one can boost the absorption for solar radiation by 25% while utilizing less than half of the semiconductor material (250% increase in the light absorption per unit volume of material). These results significantly advance our understanding of the way sunlight is absorbed by one-dimensional semiconductor nanostructures and provide a clear, intuitive guidance for the design of efficient NW solar cells. The presented approach is universal to any semiconductor and a wide range of nanostructures; as such, it provides a new PV platform technology.

  15. Optical limiting materials

    DOEpatents

    McBranch, Duncan W.; Mattes, Benjamin R.; Koskelo, Aaron C.; Heeger, Alan J.; Robinson, Jeanne M.; Smilowitz, Laura B.; Klimov, Victor I.; Cha, Myoungsik; Sariciftci, N. Serdar; Hummelen, Jan C.

    1998-01-01

    Optical limiting materials. Methanofullerenes, fulleroids and/or other fullerenes chemically altered for enhanced solubility, in liquid solution, and in solid blends with transparent glass (SiO.sub.2) gels or polymers, or semiconducting (conjugated) polymers, are shown to be useful as optical limiters (optical surge protectors). The nonlinear absorption is tunable such that the energy transmitted through such blends saturates at high input energy per pulse over a wide range of wavelengths from 400-1100 nm by selecting the host material for its absorption wavelength and ability to transfer the absorbed energy into the optical limiting composition dissolved therein. This phenomenon should be generalizable to other compositions than substituted fullerenes.

  16. Damage tolerant light absorbing material

    DOEpatents

    Lauf, R.J.; Hamby, C. Jr.; Akerman, M.A.; Seals, R.D.

    1993-09-07

    A light absorbing article comprised of a composite of carbon-bonded carbon fibers, is prepared by: blending carbon fibers with a carbonizable organic powder to form a mixture; dispersing the mixture into an aqueous slurry; vacuum molding the aqueous slurry to form a green article; drying and curing the green article to form a cured article; and, carbonizing the cured article at a temperature of at least about 1000 C to form a carbon-bonded carbon fiber light absorbing composite article having a bulk density less than 1 g/cm[sup 3]. 9 figures.

  17. Damage tolerant light absorbing material

    DOEpatents

    Lauf, Robert J.; Hamby, Jr., Clyde; Akerman, M. Alfred; Seals, Roland D.

    1993-01-01

    A light absorbing article comprised of a composite of carbon-bonded carbon fibers, prepared by: blending carbon fibers with a carbonizable organic powder to form a mixture; dispersing the mixture into an aqueous slurry; vacuum molding the aqueous slurry to form a green article; drying and curing the green article to form a cured article; and, carbonizing the cured article at a temperature of at least about 1000.degree. C. to form a carbon-bonded carbon fiber light absorbing composite article having a bulk density less than 1 g/cm.sup.3.

  18. Magnetic field effects on microwave absorbing materials

    NASA Technical Reports Server (NTRS)

    Goldberg, Ira; Hollingsworth, Charles S.; Mckinney, Ted M.

    1991-01-01

    The objective of this program was to gather information to formulate a microwave absorber that can work in the presence of strong constant direct current (DC) magnetic fields. The program was conducted in four steps. The first step was to investigate the electrical and magnetic properties of magnetic and ferrite microwave absorbers in the presence of strong magnetic fields. This included both experimental measurements and a literature survey of properties that may be applicable to finding an appropriate absorbing material. The second step was to identify those material properties that will produce desirable absorptive properties in the presence of intense magnetic fields and determine the range of magnetic field in which the absorbers remain effective. The third step was to establish ferrite absorber designs that will produce low reflection and adequate absorption in the presence of intense inhomogeneous static magnetic fields. The fourth and final step was to prepare and test samples of such magnetic microwave absorbers if such designs seem practical.

  19. Multilayer Radar Absorbing Non-Woven Material

    NASA Astrophysics Data System (ADS)

    Dedov, A. V.; Nazarov, V. G.

    2016-06-01

    We study the electrical properties of multilayer radar absorbing materials obtained by adding nonwoven sheets of dielectric fibers with an intermediate layer of electrically conductive carbon fibers. Multilayer materials that absorb electromagnetic radiation in a wide frequency range are obtained by varying the content of the carbon fibers. The carbon-fiber content dependent mechanism of absorption of electromagnetic radiation by sheets and multilayer materials is considered.

  20. Controlling optical absorption in metamaterial absorbers for plasmonic solar cells

    NASA Astrophysics Data System (ADS)

    Adams, Wyatt; Vora, Ankit; Gwamuri, Jephias; Pearce, Joshua M.; Güney, Durdu Ö.

    2015-08-01

    Metals in the plasmonic metamaterial absorbers for photovoltaics constitute undesired resistive heating. However, tailoring the geometric skin depth of metals can minimize resistive losses while maximizing the optical absorbance in the active semiconductors of the photovoltaic device. Considering experimental permittivity data for InxGa1-xN, absorbance in the semiconductor layers of the photovoltaic device can reach above 90%. The results here also provides guidance to compare the performance of different semiconductor materials. This skin depth engineering approach can also be applied to other optoelectronic devices, where optimizing the device performance demands minimizing resistive losses and power consumption, such as photodetectors, laser diodes, and light emitting diodes.

  1. Radar Absorbing Materials for Cube Stealth Satellite

    NASA Astrophysics Data System (ADS)

    Micheli, D.; Pastore, R.; Vricella, A.; Marchetti, M.

    A Cube Stealth Satellite is proposed for potential applications in defense system. Particularly, the faces of the satellite exposed to the Earth are made of nanostructured materials able to absorb radar surveillance electromagnetic waves, conferring stealth capability to the cube satellite. Microwave absorbing and shielding material tiles are proposed using composite materials consisting in epoxy-resin and carbon nanotubes filler. The electric permittivity of the composite nanostructured materials is measured and discussed. Such data are used by the modeling algorithm to design the microwave absorbing and the shielding faces of the cube satellite. The electromagnetic modeling takes into account for several incidence angles (0-80°), extended frequency band (2-18 GHz), and for the minimization of the electromagnetic reflection coefficient. The evolutionary algorithm used for microwave layered microwave absorber modeling is the recently developed Winning Particle Optimization. The mathematical model of the absorbing structure is finally experimentally validated by comparing the electromagnetic simulation to the measurement of the manufactured radar absorber tile. Nanostructured composite materials manufacturing process and electromagnetic reflection measurements methods are described. Finally, a finite element method analysis of the electromagnetic scattering by cube stealth satellite is performed.

  2. Design and Manufacture of Energy Absorbing Materials

    ScienceCinema

    Duoss, Eric

    2016-07-12

    Learn about an ordered cellular material that has been designed and manufactured using direct ink writing (DIW), a 3-D printing technology being developed at LLNL. The new material is a patterned cellular material that can absorb mechanical energy-a cushion-while also providing protection against sheering. This material is expected to find utility in application spaces that currently use unordered foams, such as sporting and consumer goods as well as defense and aerospace.

  3. Design and Manufacture of Energy Absorbing Materials

    SciTech Connect

    Duoss, Eric

    2014-05-28

    Learn about an ordered cellular material that has been designed and manufactured using direct ink writing (DIW), a 3-D printing technology being developed at LLNL. The new material is a patterned cellular material that can absorb mechanical energy-a cushion-while also providing protection against sheering. This material is expected to find utility in application spaces that currently use unordered foams, such as sporting and consumer goods as well as defense and aerospace.

  4. Absorber Materials at Room and Cryogenic Temperatures

    SciTech Connect

    F. Marhauser, T.S. Elliott, A.T. Wu, E.P. Chojnacki, E. Savrun

    2011-09-01

    We recently reported on investigations of RF absorber materials at cryogenic temperatures conducted at Jefferson Laboratory (JLab). The work was initiated to find a replacement material for the 2 Kelvin low power waveguide Higher Order Mode (HOM) absorbers employed within the original cavity cryomodules of the Continuous Electron Beam Accelerator Facility (CEBAF). This effort eventually led to suitable candidates as reported in this paper. Furthermore, though constrained by small funds for labor and resources, we have analyzed a variety of lossy ceramic materials, several of which could be usable as HOM absorbers for both normal conducting and superconducting RF structures, e.g. as loads in cavity waveguides and beam tubes either at room or cryogenic temperatures and, depending on cooling measures, low to high operational power levels.

  5. Tech Transfer Webinar: Energy Absorbing Materials

    ScienceCinema

    Duoss, Eric

    2016-07-12

    A new material has been designed and manufactured at LLNL that can absorb mechanical energy--a cushion--while also providing protection against sheering. This ordered cellular material is 3D printed using direct ink writing techniques under development at LLNL. It is expected to find utility in application spaces that currently use unordered foams, such as sporting and consumer goods as well as defense and aerospace.

  6. Tech Transfer Webinar: Energy Absorbing Materials

    SciTech Connect

    Duoss, Eric

    2014-06-17

    A new material has been designed and manufactured at LLNL that can absorb mechanical energy--a cushion--while also providing protection against sheering. This ordered cellular material is 3D printed using direct ink writing techniques under development at LLNL. It is expected to find utility in application spaces that currently use unordered foams, such as sporting and consumer goods as well as defense and aerospace.

  7. Durability of Polymeric Glazing and Absorber Materials

    SciTech Connect

    Jorgensen, G.; Terwilliger, K.; Bingham, C.; Lindquist, C.; Milbourne, M.

    2005-11-01

    The Solar Heating and Lighting Program has set the goal of reducing the cost of solar water heating systems by at least 50%. An attractive approach to such large cost reduction is to replace glass and metal parts with less-expensive, lighter-weight, more-integrated polymeric components. The key challenge with polymers is to maintain performance and assure requisite durability for extended lifetimes. We have begun evaluation of several new UV-screened polycarbonate sheet glazing constructions. This has involved interactions with several major polymer industry companies to obtain improved candidate samples. Proposed absorber materials were tested for UV resistance, and appear adequate for unglazed ICS absorbers.

  8. A high absorbance material for solar collectors' applications

    NASA Astrophysics Data System (ADS)

    Oliva, A. I.; Maldonado, R. D.; Díaz, E. A.; Montalvo, A. I.

    2013-06-01

    In this work, we proposed a low cost material to be used as an excellent absorber for solar collectors, to increase its thermal efficiency by the high capacity to absorb solar radiation. The material, known as "smoke black" (soot) can be obtained by the incomplete combustion of organic materials, such as the oxygen-acetylene, paraffin, or candles. A comparative analysis between the optical properties (reflectance, absorbance, and emissivity) measured on three covered copper surfaces (without paint, with a commercial matte black paint, and with smoke black) shows amazing optical results for the smoke black. Reflectance values of the smoke black applied over copper surfaces improves 56 times the values obtained from commercial black paints. High values of emissivity (E=0.9988) were measured on the surface covered with smoke black by spectrophotometry in the UV-VIS range, which represents about 7% of increment as compared with the value obtained for commercial black paints (E=0.938). The proposed high absorbance material can be easily applied on any kind of surfaces at low cost.

  9. Investigations on Absorber Materials at Cryogenic Temperatures

    SciTech Connect

    Marhauser, Frank; Elliott, Thomas; Rimmer, Robert

    2009-05-01

    In the framework of the 12 GeV upgrade project for the Continuous Electron Beam Accelerator Facility (CEBAF) improvements are being made to refurbish cryomodules housing Thomas Jefferson National Accelerator Facility's (JLab) original 5-cell cavities. Recently we have started to look into a possible simplification of the existing Higher Order Mode (HOM) absorber design combined with the aim to find alternative material candidates. The absorbers are implemented in two HOM-waveguides immersed in the helium bath and operate at 2 K temperature. We have built a cryogenic setup to perform measurements on sample load materials to investigate their lossy characteristics and variations from room temperature down to 2 K. Initial results are presented in this paper.

  10. Optical analysis of solar energy tubular absorbers.

    PubMed

    Saltiel, C; Sokolov, M

    1982-11-15

    The energy absorbed by a solar energy tubular receiver element for a single incident ray is derived. Two types of receiver elements were analyzed: (1) an inner tube with an absorbing coating surrounded by a semitransparent cover tube, and (2) a semitransparent inner tube filled with an absorbing fluid surrounded by a semitransparent cover tube. The formation of ray cascades in the semitransparent tubes is considered. A numerical simulation to investigate the influence of the angle of incidence, sizing, thickness, and coefficient of extinction of the tubes was performed. A comparison was made between receiver elements with and without cover tubes. Ray tracing analyses in which rays were followed within the tubular receiver element as well as throughout the rest of the collector were performed for parabolic and circular trough concentrating collectors.

  11. Tunable enhanced optical absorption of graphene using plasmonic perfect absorbers

    SciTech Connect

    Cai, Yijun; Zhu, Jinfeng; Liu, Qing Huo

    2015-01-26

    Enhancement and manipulation of light absorption in graphene is a significant issue for applications of graphene-based optoelectronic devices. In order to achieve this purpose in the visible region, we demonstrate a design of a graphene optical absorber inspired by metal-dielectric-metal metamaterial for perfect absorption of electromagnetic waves. The optical absorbance ratios of single and three atomic layer graphene are enhanced up to 37.5% and 64.8%, respectively. The graphene absorber shows polarization-dependence and tolerates a wide range of incident angles. Furthermore, the peak position and bandwidth of graphene absorption spectra are tunable in a wide wavelength range through a specific structural configuration. These results imply that graphene in combination with plasmonic perfect absorbers have a promising potential for developing advanced nanophotonic devices.

  12. New Solutions for Energy Absorbing Materials

    DTIC Science & Technology

    2012-11-01

    effective material properties of the microstructure have been obtained using finite element analysis and the overall behavior of a... effective material properties of the microstructure have been obtained using finite element analysis and the overall behavior of a composite material ... Materials Page 5 of 68 particulate composite material is assumed to behave as an effective homogeneous medium. The properties of the effective medium

  13. Novel Ultraviolet Light Absorbing Polymers For Optical Applications

    NASA Astrophysics Data System (ADS)

    Doddi, Namassivaya; Yamada, Akira; Dunks, Gary B.

    1988-07-01

    Ultraviolet light absorbing monomers have been developed that can be copolymerized with acrylates. The composition of the resultant stable copolymers can be adjusted to totally block the transmission of light below about 430 nm. Fabrication of lenses from the materials is accomplished by lathe cutting and injection molding procedures. These ultraviolet light absorbing materials are non-mutagenic and non-toxic and are currently being used in intraocular lenses.

  14. Infrared fiber optic materials

    NASA Technical Reports Server (NTRS)

    Feigelson, Robert S.

    1987-01-01

    The development of IR fiber optics for use in astronomical and other space applications is summarized. Candidate materials were sought for use in the 1 to 200 micron and the 200 to 1000 micron wavelength range. Synthesis and optical characterization were carried out on several of these materials in bulk form. And the fabrication of a few materials in single crystal fiber optic form were studied.

  15. Development of optical tools for the characterization of selective solar absorber at elevated temperature

    NASA Astrophysics Data System (ADS)

    Giraud, Philemon; Braillon, Julien; Delord, Christine; Raccurt, Olivier

    2016-05-01

    Durability of solar components for CSP (Concentrated Solar Power Plant) technologies is a key point to lower cost and ensure their large deployment. These technologies concentrated the solar radiation by means of mirrors on a receiver tube where it is collected as thermal energy. The absorbers are submitted to strong environmental constraints and the degradation of their optical properties (emittance and solar absorbance) have a direct impact on performance. The objective is to develop new optical equipment for characterization of this solar absorber in condition of use that is to say in air and at elevated temperature. In this paper we present two new optical test benches developed for optical characterization of solar absorbers in condition of use up to 800°C. The first equipment is an integrated sphere with heated sample holder which measures the hemispherical reflectance between 280 and 2500 nm to calculate the solar absorbance at high temperature. The second optical test bench measures the emittance of samples up to 1000°C in the range of 1.25 to 28.57 µm. Results of high temperature measurements on a series of metallic absorbers with selective coating and refractory material for high thermal receiver are presented.

  16. Structural and optical properties of copper-coated substrates for solar thermal absorbers

    NASA Astrophysics Data System (ADS)

    Pratesi, Stefano; De Lucia, Maurizio; Meucci, Marco; Sani, Elisa

    2016-10-01

    Spectral selectivity, i.e. merging a high absorbance at sunlight wavelengths to a low emittance at the wavelengths of thermal spectrum, is a key characteristics for materials to be used for solar thermal receivers. It is known that spectrally selective absorbers can raise the receiver efficiency for all solar thermal technologies. Tubular sunlight receivers for parabolic trough collector (PTC) systems can be improved by the use of spectrally selective coatings. Their absorbance is increased by deposing black films, while the thermal emittance is minimized by the use of properly-prepared substrates. In this work we describe the intermediate step in the fabrication of black-chrome coated solar absorbers, namely the fabrication and characterization of copper coatings on previously nickel-plated stainless steel substrates. We investigate the copper surface features and optical properties, correlating them to the coating thickness and to the deposition process, in the perspective to assess optimal conditions for solar absorber applications.

  17. Shock Tube Test for Energy Absorbing Materials

    DTIC Science & Technology

    2013-09-13

    Compressed  Air  Cylinder Driver  Section Driven  Section Max Driver  Pressure: 200 PSI Diaphragm Striker Material Nylon Striker Face Diameter...part of a study of materials for an impact attenuating helmet liner project (3). Table 2. Foam materials for testing (7) (8) (9) Manufacturer...including application in helmet liners (8). Zorbium™ is the viscoelastic polyurethane foam used in military helmet suspension system pads (9). 8

  18. Optical fibre-coupled cryogenic radiometer with carbon nanotube absorber

    NASA Astrophysics Data System (ADS)

    Livigni, David J.; Tomlin, Nathan A.; Cromer, Christopher L.; Lehman, John H.

    2012-04-01

    A cryogenic radiometer was constructed for direct-substitution optical-fibre power measurements. The cavity is intended to operate at the 3 K temperature stage of a dilution refrigerator or 4.2 K stage of a liquid cryostat. The optical fibre is removable for characterization. The cavity features micromachined silicon centring rings to thermally isolate the optical fibre as well as an absorber made from micromachined silicon on which vertically aligned carbon nanotubes were grown. Measurements of electrical substitution, optical absorption and temperature change indicate that the radiometer is capable of measuring a power level of 10 nW with approximate responsivity of 155 nW K-1 and 1/e time constant of 13 min. An inequivalence between optical and electrical power of approximately 10% was found, but the difference was largely attributable to unaccounted losses in the optical fibre.

  19. Thermally Resilient, Broadband Optical Absorber from UV to IR Derived from Carbon Nanostructures

    NASA Technical Reports Server (NTRS)

    Kaul, Anupama B.; Coles, James B.

    2012-01-01

    Optical absorber coatings have been developed from carbon-based paints, metal blacks, or glassy carbon. However, such materials are not truly black and have poor absorption characteristics at longer wavelengths. The blackness of such coatings is important to increase the accuracy of calibration targets used in radiometric imaging spectrometers since blackbody cavities are prohibitively large in size. Such coatings are also useful potentially for thermal detectors, where a broadband absorber is desired. Au-black has been a commonly used broadband optical absorber, but it is very fragile and can easily be damaged by heat and mechanical vibration. An optically efficient, thermally rugged absorber could also be beneficial for thermal solar cell applications for energy harnessing, particularly in the 350-2,500 nm spectral window. It has been demonstrated that arrays of vertically oriented carbon nanotubes (CNTs), specifically multi-walled-carbon- nanotubes (MWCNTs), are an exceptional optical absorber over a broad range of wavelengths well into the infrared (IR). The reflectance of such arrays is 100x lower compared to conventional black materials, such as Au black in the spectral window of 350-2,500 nm. Total hemispherical measurements revealed a reflectance of approximately equal to 1.7% at lambda approximately equal to 1 micrometer, and at longer wavelengths into the infrared (IR), the specular reflectance was approximately equal to 2.4% at lambda approximately equal to 7 micrometers. The previously synthesized CNTs for optical absorber applications were formed using water-assisted thermal chemical vapor deposition (CVD), which yields CNT lengths in excess of 100's of microns. Vertical alignment, deemed to be a critical feature in enabling the high optical absorption from CNT arrays, occurs primarily via the crowding effect with thermal CVD synthesized CNTs, which is generally not effective in aligning CNTs with lengths less than 10 m. Here it has been shown that the

  20. Contribution of recoil atoms to irradiation damage in absorber materials

    NASA Astrophysics Data System (ADS)

    Simeone, D.; Hablot, O.; Micalet, V.; Bellon, P.; Serruys, Y.

    1997-08-01

    Absorbing materials are used to control the reactivity of nuclear reactors by taking advantage of nuclear reactions (e.g., 10B(n,α) 7Li) where neutrons are absorbed. During such reactions, energetic recoils are produced. As a result, radiation damage in absorbing materials originates both from these nuclear reactions and from elastic collisions between neutrons and atoms. This damage eventually leads to a partial destruction of the materials, and this is the main limitation on their lifetime in nuclear reactors. Using a formalism developed to calculate displacements per atoms (dpa) in a multi atomic target, we have calculated damages in terms of displacements per atom in a (n,α) absorbing material taking into account geometrical effects of 10 boron self shielding and transmutation reactions induced by neutrons inside the absorber. Radiation damage is calculated for boron carbide and hafnium diboride ceramics in a Pressurized Water Reactor environment. It is shown that recoils produced by nuclear reactions account for the main part of the radiation damage created in these ceramics. Damages are calculated as a function of the distance from the center of an absorber pellet. Due to the self-shielding effect, these damage curves exhibit sharp maxima, the position of which changes in time.

  1. Determining the Absorbance Spectra of Photochromic Materials From Measured Spectrophotometer Data

    NASA Technical Reports Server (NTRS)

    Downie, John D.

    1998-01-01

    If a two-state photochromic material is optically bleached, the absorbance spectrum data measured by a spectrophotometer is in general comprised of components from both the ground state and the upper state. Under general conditions, it may be difficult to extract the actual upper state spectrum from the spectrum of the bleached material. A simple algorithm is presented here for the recovery of the pure absorbance spectra of the upper state of a material such as bacteriorhodopsin, given single wavelength bleaching illumination, steady-state conditions, and accurate knowledge of phototransition rates and thermal decay rates.

  2. An Introduction to Radar Absorbent Materials (RAM),

    DTIC Science & Technology

    1986-02-01

    transition metal ion, a combination of two or more such ions or alterna- tively a combination of mono- and tri- valent ions that maintains overall... valent ions. Not only does the wide variety of compositions lead to a wide variation in the electromagnetic material constants of ferrites, but, even... Giordano , "Measurement of Standing Wave Ratio", ch. 2 in M Sucher, J Fox (Eds) "Handbook of Microwave Measurements, Vol 1", Polytechnic Press of

  3. Thin films of copper antimony sulfide: A photovoltaic absorber material

    SciTech Connect

    Ornelas-Acosta, R.E.; Shaji, S.; Avellaneda, D.; Castillo, G.A.; Das Roy, T.K.; Krishnan, B.

    2015-01-15

    Highlights: • CuSbS{sub 2} thin films were prepared by heating Sb{sub 2}S{sub 3}/Cu layers. • Analyzed the structure, composition, optical, and electrical properties. • PV structures: glass/SnO{sub 2}:F/n-CdS/p-CuSbS{sub 2}/C/Ag were formed at different conditions. • The PV parameters (J{sub sc}, V{sub oc}, and FF) were evaluated from the J–V characteristics. • J{sub sc}: 0.52–3.20 mA/cm{sup 2}, V{sub oc}:187–323 mV, FF: 0.27–0.48 were obtained. - Abstract: In this work, we report preparation and characterization of CuSbS{sub 2} thin films by heating glass/Sb{sub 2}S{sub 3}/Cu layers and their use as absorber material in photovoltaic structures: glass/SnO{sub 2}:F/n-CdS/p-CuSbS{sub 2}/C/Ag. The Sb{sub 2}S{sub 3} thin films of 600 nm were prepared by chemical bath deposition on which copper thin films of 50 nm were thermally evaporated, and the glass/Sb{sub 2}S{sub 3}/Cu multilayers were heated in vacuum at different temperatures. X-ray diffraction analysis showed the formation of orthorhombic CuSbS{sub 2} after heating the precursor layers. Studies on identification and chemical state of the elements were done using X-ray photoelectron spectroscopy. The optical band gap of the CuSbS{sub 2} thin films was 1.55 eV and the thin films were photoconductive. The photovoltaic parameters of the devices using CuSbS{sub 2} as absorber and CdS as window layer were evaluated from the J–V curves, yielding J{sub sc}, V{sub oc}, and FF values in the range of 0.52–3.20 mA/cm{sup 2}, 187–323 mV, and 0.27–0.48, respectively, under illumination of AM1.5 radiation.

  4. Nanometre optical coatings based on strong interference effects in highly absorbing media.

    PubMed

    Kats, Mikhail A; Blanchard, Romain; Genevet, Patrice; Capasso, Federico

    2013-01-01

    Optical coatings, which consist of one or more films of dielectric or metallic materials, are widely used in applications ranging from mirrors to eyeglasses and photography lenses. Many conventional dielectric coatings rely on Fabry-Perot-type interference, involving multiple optical passes through transparent layers with thicknesses of the order of the wavelength to achieve functionalities such as anti-reflection, high-reflection and dichroism. Highly absorbing dielectrics are typically not used because it is generally accepted that light propagation through such media destroys interference effects. We show that under appropriate conditions interference can instead persist in ultrathin, highly absorbing films of a few to tens of nanometres in thickness, and demonstrate a new type of optical coating comprising such a film on a metallic substrate, which selectively absorbs various frequency ranges of the incident light. These coatings have a low sensitivity to the angle of incidence and require minimal amounts of absorbing material that can be as thin as 5-20 nm for visible light. This technology has the potential for a variety of applications from ultrathin photodetectors and solar cells to optical filters, to labelling, and even the visual arts and jewellery.

  5. Nanometre optical coatings based on strong interference effects in highly absorbing media

    NASA Astrophysics Data System (ADS)

    Kats, Mikhail A.; Blanchard, Romain; Genevet, Patrice; Capasso, Federico

    2013-01-01

    Optical coatings, which consist of one or more films of dielectric or metallic materials, are widely used in applications ranging from mirrors to eyeglasses and photography lenses. Many conventional dielectric coatings rely on Fabry-Perot-type interference, involving multiple optical passes through transparent layers with thicknesses of the order of the wavelength to achieve functionalities such as anti-reflection, high-reflection and dichroism. Highly absorbing dielectrics are typically not used because it is generally accepted that light propagation through such media destroys interference effects. We show that under appropriate conditions interference can instead persist in ultrathin, highly absorbing films of a few to tens of nanometres in thickness, and demonstrate a new type of optical coating comprising such a film on a metallic substrate, which selectively absorbs various frequency ranges of the incident light. These coatings have a low sensitivity to the angle of incidence and require minimal amounts of absorbing material that can be as thin as 5-20 nm for visible light. This technology has the potential for a variety of applications from ultrathin photodetectors and solar cells to optical filters, to labelling, and even the visual arts and jewellery.

  6. Absorbed XFEL Dose in the Components of the LCLS X-Ray Optics

    SciTech Connect

    Hau-Riege, Stefan

    2010-12-03

    There is great concern that the short, intense XFEL pulse of the LCLS will damage the optics that will be placed into the beam. We have analyzed the extent of the problem by considering the anticipated materials and position of the optical components in the beam path, calculated the absorbed dose as a function of photon energy, and compared these doses with the expected doses required (i) to observe rapid degradation due to thermal fatigue, (ii) to reach the melting temperature, or (iii) to actually melt the material. We list the materials that are anticipated to be placed into the Linac Coherent Light Source (LCLS) x-ray free electron laser (XFEL) beam line, their positions, and the absorbed dose, and compare this dose with anticipated damage thresholds.

  7. Optical properties of solid-core photonic crystal fibers filled with nonlinear absorbers.

    PubMed

    Butler, James J; Bowcock, Alec S; Sueoka, Stacey R; Montgomery, Steven R; Flom, Steven R; Friebele, E Joseph; Wright, Barbara M; Peele, John R; Pong, Richard G S; Shirk, James S; Hu, Jonathan; Menyuk, Curtis R; Taunay, T F

    2013-09-09

    A theoretical and experimental investigation of the transmission of solid-core photonic crystal fibers (PCFs) filled with nonlinear absorbers shows a sharp change in the threshold for optical limiting and in leakage loss as the refractive index of the material in the holes approaches that of the glass matrix. Theoretical calculations of the mode profiles and leakage loss of the PCF are in agreement with experimental results and indicate that the change in limiting response is due to the interaction of the evanescent field of the guided mode with the nonlinear absorbers in the holes.

  8. Stretchable optical device with electrically tunable absorbance and fluorescence

    NASA Astrophysics Data System (ADS)

    Hanley, Cormac A.; Gun'ko, Yurii K.; Frediani, Gabriele; Carpi, Federico

    2014-01-01

    We report the first proof-of-principle demonstration of a quantum dot (QD) doped dielectric elastomer actuator as a new stretchable optical device with electrically tunable optical absorbance and fluorescence. A polyacrylate dielectric elastomer film with carbon grease electrodes was loaded with organic-phase CdSe/CdS luminescent QDs. This study moved from the working hypothesis that electrical actuation of the QD doped elastomer varies the distances among each QD and its neighbours in the structure, modifying the volume and/or surface density of QDs, and thus leading to variable interactions among them, therefore changing the optical spectral properties of the QDs in the elastomer matrix. Experiments revealed that applied voltages increased the UV-vis absorbance, and decreased the photoluminescence (fluorescence) intensity and lifetimes. The former effect proved the working hypothesis, while the latter was not expected. The drop in photoluminescence intensity was found to be caused by the high fringe electric field generated by the actuator. The paper presents characterizations and discusses results, highlighting potentials and challenges of such systems.

  9. Optical materials research.

    PubMed

    Parsons, W F

    1972-01-01

    There are eras in research when days are filled with excitement because unique materials are being produced and researchers "think what nobody else has thought" (Albert von Szent Gyorgyi). Such were the periods when many new optical glasses emerged from the laboratories of the Eastman Kodak Company and when the hot pressing technology was applied to produce new polycrystalline materials. This paper discusses the people and accomplishments of those periods.

  10. Sound-absorbing slabs and structures based on granular materials (bound and unbound). [energy absorbing efficiency of porous material

    NASA Technical Reports Server (NTRS)

    Petre-Lazar, S.; Popeea, G.

    1974-01-01

    Sound absorbing slabs and structures made up of bound or unbound granular materials are considered and how to manufacture these elements at the building site. The raw material is a single grain powder (sand, expanded blast furnace slag, etc.) that imparts to the end products an apparent porosity of 25-45% and an energy dissipation within the structure leading to absorption coefficients that can be compared with those of mineral wool and urethane.

  11. Mechanism of resonant perfect optical absorber, design rules, and applications

    NASA Astrophysics Data System (ADS)

    Guan, Zhiqiang; Wang, Wenqiang; Xu, Hongxing

    2016-11-01

    The mechanism of resonant perfect optical absorber (POA) is revealed by coupled mode method. The POA structures here is an air/grating/film/air four region asymmetric structures. Different with common POA structures that require metal film at the bottom to block the transmission of light, the film in our structures serves as a total internal reflection layer which blocks the transmission of light. To demonstrate that, mode dispersion analyses are provided for each mode by the phase plots of the scattering coefficients on each interface. The sufficient and necessary conditions of perfect optical absorption are derived from the phase matching conditions. Three analytical formulae are given for prompt and accurate design rules when the incident wavelength is slightly larger than the periodicity. Several fabrication schemes are discussed. The features of ultrathin structures, widely tunable POA wavelength, and high Q factor make our structures promising for applications in coherent thermal emission, filtering, sensing and modulation.

  12. Optical Properties and Aging of Light Absorbing Secondary Organic Aerosol

    SciTech Connect

    Liu, Jiumeng; Lin, Peng; Laskin, Alexander; Laskin, Julia; Kathmann, Shawn M.; Wise, Matthew E.; Caylor, Ryan; Imholt, Felisha; Selimovic, Vanessa; Shilling, John E.

    2016-10-14

    The light-absorbing organic aerosol (OA), commonly referred to as “brown carbon (BrC)”, has attracted considerable attention in recent years because of its potential to affect atmospheric radiation balance, especially in the ultraviolet region and thus impact photochemical processes. A growing amount of data has indicated that BrC is prevalent in the atmosphere, which has motivated numerous laboratory and field studies; however, our understanding of the relationship between the chemical composition and optical properties of BrC remains limited. We conducted chamber experiments to investigate the effect of various VOC precursors, NOx concentrations, photolysis time and relative humidity (RH) on the light absorption of selected secondary organic aerosols (SOA). Light absorption of chamber generated SOA samples, especially aromatic SOA, was found to increase with NOx concentration, at moderate RH, and for the shortest photolysis aging times. The highest mass absorption coefficients (MAC) value is observed from toluene SOA products formed under high NOx conditions at moderate RH, in which nitro-aromatics were previously identified as the major light absorbing compounds. BrC light absorption is observed to decrease with photolysis time, correlated with a decline of the organonitrate fraction of SOA. SOA formed from mixtures of aromatics and isoprene absorb less visible and UV light than SOA formed from aromatic precursors alone on a mass basis. However, the mixed-SOA absorption was underestimated when optical properties were predicted using a two-product SOA formation model, as done in many current climate models. Further investigation, including analysis on detailed mechanisms, are required to explain the discrepancy.

  13. Application of Absorbable Hemostatic Materials Observed in Thyroid Operation

    NASA Astrophysics Data System (ADS)

    Li, Yan-Ming; Liang, Zhen-Zhen; Song, Yan

    2016-05-01

    To observe the application effects of the absorbable hemostatic materials in thyroid operation. Methods: From May 2014 to January 2015, 100 patients with thyroid surgery in our university affiliated hospital were selected as the research object. Randomly divided into experimental group and control group, 50 cases in each group. Application of absorbable hemostatic hemostatic materials in the experimental group during the operation, the control group using the traditional mechanical methods of hemostasis hemostasis to observe the operation time, bleeding volume, postoperative drainage volume, complications and hospital stay of the two groups. Results: The operation time, bleeding volume, postoperative drainage and hospital stay in the experimental group were significantly lower in the study group than in the control group, and the difference between the two groups was statistically significant (P< 0.05); The satisfaction of patients in the experimental group was significantly higher than that in the control group, the difference was statistically significant in the two groups (P < 0.05); There was no significant difference in the incidence of wound bleeding complications between the study group and the control group (P > 0.05). Conclusion: Absorbable hemostatic materials can effectively shorten the operation time, reduce intraoperative blood loss and postoperative drainage, reduce the length of hospital stay and improve the success rate of surgery and patient satisfaction, which is worthy to be popularized in clinical thyroid surgery.

  14. The changes in optical absorbance of ZrO2 thin film with the rise of the absorbed dose

    NASA Astrophysics Data System (ADS)

    Abayli, D.; Baydogan, N.

    2016-03-01

    In this study, zirconium oxide (ZrO2) thin film samples prepared by sol-gel method were irradiated using Co-60 radioisotope as gamma source. Then, it was investigated the ionizing effect on optical properties of ZrO2 thin film samples with the rise of the absorbed dose. The changes in the optical absorbance of ZrO2 thin films were determined by using optical transmittance and the reflectance measurements in the range between 190 - 1100 nm obtained from PG Instruments T80 UV-Vis spectrophotometer.

  15. An all-optical poling investigation of low absorbing azobenzene side-chain polymer films

    NASA Astrophysics Data System (ADS)

    Jia, Yajie; Wang, Gongming; Guo, Bin; Su, Wei; Zhang, Qijin

    2004-09-01

    All optical poling (AOP) processes of both the typical AOP material disperse red 1 (DR1) copolymer and a low absorbing side-chain poly(2-[4-(4-cyanophenylazo)phenoxy] hexyl methacrylate), called PCN6, were examined and compared. The trade-off between the optical seeding efficiency and the transparency of the nonlinear polymer was considered. Quasi-phase matched (QPM) second harmonic generation (SHG) in PCN6 films was demonstrated. A relaxation retardation effect of the photo-induced khgr(2) was also observed in thick PCN6 films.

  16. Exchanging Ohmic Losses in Metamaterial Absorbers with Useful Optical Absorption for Photovoltaics

    PubMed Central

    Vora, Ankit; Gwamuri, Jephias; Pala, Nezih; Kulkarni, Anand; Pearce, Joshua M.; Güney, Durdu Ö.

    2014-01-01

    Using metamaterial absorbers, we have shown that metallic layers in the absorbers do not necessarily constitute undesired resistive heating problem for photovoltaics. Tailoring the geometric skin depth of metals and employing the natural bulk absorbance characteristics of the semiconductors in those absorbers can enable the exchange of undesired resistive losses with the useful optical absorbance in the active semiconductors. Thus, Ohmic loss dominated metamaterial absorbers can be converted into photovoltaic near-perfect absorbers with the advantage of harvesting the full potential of light management offered by the metamaterial absorbers. Based on experimental permittivity data for indium gallium nitride, we have shown that between 75%–95% absorbance can be achieved in the semiconductor layers of the converted metamaterial absorbers. Besides other metamaterial and plasmonic devices, our results may also apply to photodectors and other metal or semiconductor based optical devices where resistive losses and power consumption are important pertaining to the device performance. PMID:24811322

  17. Exchanging Ohmic losses in metamaterial absorbers with useful optical absorption for photovoltaics.

    PubMed

    Vora, Ankit; Gwamuri, Jephias; Pala, Nezih; Kulkarni, Anand; Pearce, Joshua M; Güney, Durdu Ö

    2014-05-09

    Using metamaterial absorbers, we have shown that metallic layers in the absorbers do not necessarily constitute undesired resistive heating problem for photovoltaics. Tailoring the geometric skin depth of metals and employing the natural bulk absorbance characteristics of the semiconductors in those absorbers can enable the exchange of undesired resistive losses with the useful optical absorbance in the active semiconductors. Thus, Ohmic loss dominated metamaterial absorbers can be converted into photovoltaic near-perfect absorbers with the advantage of harvesting the full potential of light management offered by the metamaterial absorbers. Based on experimental permittivity data for indium gallium nitride, we have shown that between 75%-95% absorbance can be achieved in the semiconductor layers of the converted metamaterial absorbers. Besides other metamaterial and plasmonic devices, our results may also apply to photodectors and other metal or semiconductor based optical devices where resistive losses and power consumption are important pertaining to the device performance.

  18. Negative Refraction in a Uniaxial Absorbent Dielectric Material

    ERIC Educational Resources Information Center

    Jen, Yi-Jun; Lakhtakia, Akhlesh; Yu, Ching-Wei; Lin, Chin-Te

    2009-01-01

    Refraction of light from an isotropic dielectric medium to an anisotropic dielectric material is a complicated phenomenon that can have several different characteristics not usually discussed in electromagnetics textbooks for undergraduate students. With a simple problem wherein the refracting material is uniaxial with its optic axis normal to the…

  19. Optical polarizer material

    DOEpatents

    Ebbers, Christopher A.

    1999-01-01

    Several crystals have been identified which can be grown using standard single crystals growth techniques and which have a high birefringence. The identified crystals include Li.sub.2 CO.sub.3, LiNaCO.sub.3, LiKCO.sub.3, LiRbCO.sub.3 and LiCsCO.sub.3. The condition of high birefringence leads to their application as optical polarizer materials. In one embodiment of the invention, the crystal has the chemical formula LiK.sub.(1-w-x-y) Na.sub.(1-w-x-z) Rb.sub.(1-w-y-z) Cs.sub.(1-x-y-z) CO.sub.3, where w+x+y+z=1. In another embodiment, the crystalline material may be selected from a an alkali metal carbonate and a double salt of alkali metal carbonates, where the polarizer has a Wollaston configuration, a Glan-Thompson configuration or a Glan-Taylor configuration. A method of making an LiNaCO.sub.3 optical polarizer is described. A similar method is shown for making an LiKCO.sub.3 optical polarizer.

  20. Optical polarizer material

    SciTech Connect

    Ebbers, C.A.

    1999-08-31

    Several crystals have been identified which can be grown using standard single crystals growth techniques and which have a high birefringence. The identified crystals include Li.sub.2 CO.sub.3, LiNaCO.sub.3, LiKCO.sub.3, LiRbCO.sub.3 and LiCsCO.sub.3. The condition of high birefringence leads to their application as optical polarizer materials. In one embodiment of the invention, the crystal has the chemical formula LiK.sub.(1-w-x-y) Na.sub.(1-w-x-z) Rb.sub.(1-w-y-z) Cs.sub.(1-x-y-z) CO.sub.3, where w+x+y+z=1. In another embodiment, the crystalline material may be selected from a an alkali metal carbonate and a double salt of alkali metal carbonates, where the polarizer has a Wollaston configuration, a Glan-Thompson configuration or a Glan-Taylor configuration. A method of making an LiNaCO.sub.3 optical polarizer is described. A similar method is shown for making an LiKCO.sub.3 optical polarizer.

  1. Nanocavity enhancement for ultra-thin film optical absorber.

    PubMed

    Song, Haomin; Guo, Luqing; Liu, Zhejun; Liu, Kai; Zeng, Xie; Ji, Dengxin; Zhang, Nan; Hu, Haifeng; Jiang, Suhua; Gan, Qiaoqiang

    2014-05-01

    A fundamental strategy is developed to enhance the light-matter interaction of ultra-thin films based on a strong interference effect in planar nanocavities, and overcome the limitation between the optical absorption and film thickness of energy harvesting/conversion materials. This principle is quite general and is applied to explore the spectrally tunable absorption enhancement of various ultra-thin absorptive materials including 2D atomic monolayers.

  2. Smart materials optical mirrors

    NASA Astrophysics Data System (ADS)

    Chen, Peter C.; Rabin, Douglas M.

    2014-08-01

    We report the fabrication of imaging quality optical mirrors with smooth surfaces using carbon nanotubes embedded in an epoxy matrix. CNT/epoxy is a multifunctional or `smart' composite material that has sensing capabilities and can be made to incorporate self-actuation as well. Moreover, since the precursor is a low density liquid, large and lightweight mirrors can be fabricated by processes such as replication, spincasting, and 3D printing. The technology therefore holds promise for development of a new generation of lightweight, compact `smart' telescope mirrors with figure sensing and active or adaptive figure control. We report on measurements made of optical and mechanical characteristics. We discuss possible paths for future development.

  3. Porphyrin Based Near Infrared-Absorbing Materials for Organic Photovoltaics

    NASA Astrophysics Data System (ADS)

    Zhong, Qiwen

    The conservation and transformation of energy is essential to the survival of mankind, and thus concerns every modern society. Solar energy, as an everlasting source of energy, holds one of the key solutions to some of the most urgent problems the world now faces, such as global warming and the oil crisis. Advances in technologies utilizing clean, abundant solar energy, could be the steering wheel of our societies. Solar cells, one of the major advances in converting solar energy into electricity, are now capturing people's interest all over the globe. While solar cells have been commercially available for many years, the manufacturing of solar cells is quite expensive, limiting their broad based implementation. The cost of solar cell based electricity is 15-50 cents per kilowatt hour (¢/kwh), depending on the type of solar cell, compared to 0.7 ¢/kwh for fossil fuel based electricity. Clearly, decreasing the cost of electricity from solar cells is critical for their wide spread deployment. This will require a decrease in the cost of light absorbing materials and material processing used in fabricating the cells. Organic photovoltaics (OPVs) utilize organic materials such as polymers and small molecules. These devices have the advantage of being flexible and lower cost than conventional solar cells built from inorganic semiconductors (e.g. silicon). The low cost of OPVs is tied to lower materials and fabrication costs of organic cells. However, the current power conversion efficiencies of OPVs are still below 15%, while convention crystalline Si cells have efficiencies of 20-25%. A key limitation in OPVs today is their inability to utilize the near infrared (NIR) portion of the solar spectrum. This part of the spectrum comprises nearly half of the energy in sunlight that could be used to make electricity. The first and foremost step in conversion solar energy conversion is the absorption of light, which nature has provided us optimal model of, which is

  4. Fiber optic moisture sensor with moisture-absorbing reflective target

    DOEpatents

    Kirkham, Randy R.

    1987-01-01

    A method and apparatus for sensing moisture changes by utilizing optical fiber technology. One embodiment uses a reflective target at the end of an optical fiber. The reflectance of the target varies with its moisture content and can be detected by a remote unit at the opposite end of the fiber. A second embodiment utilizes changes in light loss along the fiber length. This can be attributed to changes in reflectance of cladding material as a function of its moisture content. It can also be affected by holes or inserts interposed in the cladding material and/or fiber. Changing light levels can also be coupled from one fiber to another in an assembly of fibers as a function of varying moisture content in their overlapping lengths of cladding material.

  5. Device for Measuring Heat Capacities of Microcalorimeter Absorber Materials

    NASA Astrophysics Data System (ADS)

    Kotsubo, Vincent; Beall, James; Ullom, Joel

    2009-12-01

    We are developing a device for measuring the heat capacity of candidate absorber materials for gamma-ray microcalorimeters with the goal of finding materials with low heat capacity and high stopping power to improve detector efficiency. To date, only Sn has been effective as an absorber, and speculation is that other materials suffer from anomalously high heat capacities at low temperatures. The key component of the measurement device is a 17 mm×17 mm low heat capacity silicon platform suspended by Kevlar fibers designed for accepting 1 g to 2 g samples, and whose heat capacity can be characterized prior to attaching a sample. The platform has a thin film Pd/Au heater deposited directly on the silicon, and a semiconducting thermometer bonded to the surface. The heat capacity is determined from C = Gτ, where G is the in-situ measured conductance and x is the measured temperature decay time from a step change in applied heat. For a platform without samples, decay periods on the order of 0.3 to 0.05 seconds were measured. With samples, decay periods of several seconds are projected, allowing good resolution of the heat capacities. Several thermometers were tested in an effort to find one with the optimum characteristics for measuring platform temperatures. These included a commercial thick-film Ruthenium-oxide surface-mount resistor, a germanium NTD, and a zirconium oxy-nitride thin-film thermometer.

  6. Material Model Evaluation of a Composite Honeycomb Energy Absorber

    NASA Technical Reports Server (NTRS)

    Jackson, Karen E.; Annett, Martin S.; Fasanella, Edwin L.; Polanco, Michael A.

    2012-01-01

    A study was conducted to evaluate four different material models in predicting the dynamic crushing response of solid-element-based models of a composite honeycomb energy absorber, designated the Deployable Energy Absorber (DEA). Dynamic crush tests of three DEA components were simulated using the nonlinear, explicit transient dynamic code, LS-DYNA . In addition, a full-scale crash test of an MD-500 helicopter, retrofitted with DEA blocks, was simulated. The four material models used to represent the DEA included: *MAT_CRUSHABLE_FOAM (Mat 63), *MAT_HONEYCOMB (Mat 26), *MAT_SIMPLIFIED_RUBBER/FOAM (Mat 181), and *MAT_TRANSVERSELY_ANISOTROPIC_CRUSHABLE_FOAM (Mat 142). Test-analysis calibration metrics included simple percentage error comparisons of initial peak acceleration, sustained crush stress, and peak compaction acceleration of the DEA components. In addition, the Roadside Safety Verification and Validation Program (RSVVP) was used to assess similarities and differences between the experimental and analytical curves for the full-scale crash test.

  7. Boron-copper neutron absorbing material and method of preparation

    DOEpatents

    Wiencek, Thomas C.; Domagala, Robert F.; Thresh, Henry

    1991-01-01

    A composite, copper clad neutron absorbing material is comprised of copper powder and boron powder enriched with boron 10. The boron 10 content can reach over 30 percent by volume, permitting a very high level of neutron absorption. The copper clad product is also capable of being reduced to a thickness of 0.05 to 0.06 inches and curved to a radius of 2 to 3 inches, and can resist temperatures of 900.degree. C. A method of preparing the material includes the steps of compacting a boron-copper powder mixture and placing it in a copper cladding, restraining the clad assembly in a steel frame while it is hot rolled at 900.degree. C. with cross rolling, and removing the steel frame and further rolling the clad assembly at 650.degree. C. An additional sheet of copper can be soldered onto the clad assembly so that the finished sheet can be cold formed into curved shapes.

  8. Thin absorber EUV photomask based on mixed Ni and TaN material

    NASA Astrophysics Data System (ADS)

    Hay, Derrick; Bagge, Patrick; Khaw, Ian; Sun, Lei; Wood, Obert; Chen, Yulu; Kim, Ryoung-han; Qi, Zhengqing John; Shi, Zhimin

    2016-05-01

    Lithographic patterning at the 7 and 5 nm nodes will likely require EUV (λ=13.5 nm) lithography for many of the critical levels. All optical elements in an EUV scanner are reflective which requires the EUV photomask to be illuminated at an angle to its normal. Current scanners have an incidence of 6 degree, but future designs will be <6 degrees for high-NA systems. Non-telecentricity has been shown to cause H-V bias due to shadowing, pattern shift through focus, and image contrast lost due to apodization by the reflective mask coating. A thinner EUV absorber can dramatically reduce these issues. Ni offers better EUV absorption than Ta-based materials, which hold promise as a thinner absorber candidate. Unfortunately, the challenge of etching Ni has prevented its adoption into manufacturing. We propose a new absorber material that infuses Ni nanoparticles into the TaN host medium, allowing for the use of established Ta etching chemistry. A thinner is absorber is created due to the enhanced absorption properties of the Ni-Ta nano-composite material. Finite integral method and effective medium theory-based transfer matrix method have been independently developed to analyze the performance of the nano-composite absorption layer. We show that inserting 15% volume fraction Ni nanoparticles into 40-nm of TaN absorber material can reduce the reflection below 2% over the EUV range. Numerical simulations confirm that the reduced reflectivity is due to the increased absorption of Ni, while scattering only contributes to approximately 0.2% of the reduction in reflectivity.

  9. Development of optical tool for the characterization of selective solar absorber tubes

    NASA Astrophysics Data System (ADS)

    Braillon, Julien; Stollo, Alessio; Delord, Christine; Raccurt, Olivier

    2016-05-01

    In the Concentrated Solar Power (CSP) technologies, selective solar absorbers, which have a cylindrical geometry, are submitted to strong environmental constraints. The degradation of their optical properties (total solar absorbance and total emittance) has a direct impact on the performances. In order to know optical properties of absorber tubes, we present in this article a new optical tool developed by our laboratory which fit onto commercial spectrometers. Total solar absorbance and total emittance are calculated from total reflectance spectra measured by UV-Vis and IR spectrophotometry. To verify and validate the measurement method, we performed a comparative study between flat and cylindrical samples with same surface properties.

  10. Durable innovative solar optical materials: The international challenge

    NASA Astrophysics Data System (ADS)

    Lampert, C. M.

    1982-07-01

    A variety of optical coatings is discussed in the context of solar energy utilization. Well known coatings such as heat mirrors, selective absorbers, and reflective films are covered briefly. Emphasis is placed on the materials limitations and design choices for various lesser known optical coatings and materials. Physical and optical properties are detailed for protective antireflection films, fluorescent concentrator materials, holographic films, cold mirrors, radiative cooling surfaces, and optical switching films including electrochromic, thermochromic, photochromic, and liquid crystal types. For many of these materials research is only now being considered, and various design and durability issues must be addressed.

  11. Durable innovative solar optical materials - the international challenge

    NASA Astrophysics Data System (ADS)

    Lampert, Carl M.

    1982-04-01

    A variety of optical coatings are discussed in the context of solar energy utilization. Well known coatings such as heat mirrors, selective absorbers, and reflective films are covered briefly. Emphasis is placed on the materials limitations and design choices for various lesser known optical coatings and materials. Physical and optical properties are detailed for protective antireflection films, fluorescent concentrator materials, holographic films, cold mirrors, radiative cooling surfaces, and optical switching films including electrochromic, thermochromic, photochromic, and liquid crystal types. For many of these materials research is only now being considered, and various design and durability issues must be addressed.

  12. Durable innovative solar optical materials: the international challenge

    SciTech Connect

    Lampert, C.M.

    1982-01-01

    A variety of optical coatings are discussed in the context of solar energy utilization. Well known coatings such as heat mirrors, selective absorbers, and reflective films are covered briefly. Emphasis is placed on the materials limitations and design choices for various lesser known optical coatings and materials. Physical and optical properties are detailed for protective antireflection films, fluorescent concentrator materials, holographic films, cold mirrors, radiative cooling surfaces, and optical switching films including electrochromic, thermochromic, photochromic, and liquid crystal types. For many of these materials research is only now being considered, and various design and durability issues must be addressed.

  13. Bacteriocin typing by leakage of ultraviolet light-absorbing material.

    PubMed Central

    Farkas-Himsley, H; Pagel, A

    1977-01-01

    A rapid and reproducible method of bacteriocin typing is described based on leakage of ultraviolet light-absorbing material (UVAM), detectable in supernatants of bacteriocin-sensitive cultures, by means of a spectrophotometer. The prerequisites for reproducible results, with nonsignificant fluctuations in standard error of the mean, are: a set of standardized bacteriocins, produced under defined conditions and of determined strength. These must interact with the unknown bacterial culture in suspension and at a given ratio in order to achieve an optimal multiplicity of interaction. Pyocin and colicin typing by the "scrape and streak" technique of Gillies (J. Hyg. 62:1-10, 1963) was compared with the UVAM leakage method in 275 tests; the two tests were found to be in good agreement for the strains tested. PMID:406200

  14. Optically Nonlinear Polymeric Materials.

    DTIC Science & Technology

    1983-01-01

    optical chromophores into the hydrophobic portions of the polymer, second order . ,nonlinear optical effects may be obtained. Experimental 01 0...8217V cinnamaldehyde , giving the polymer shown in Figure 3. This chromophore should have greater optical nonlinearity because of its better electron

  15. EDITORIAL: Optics of nanocomposite materials Optics of nanocomposite materials

    NASA Astrophysics Data System (ADS)

    Kaczmarek, Malgosia; Tomita, Yasuo

    2009-02-01

    This special issue aims to consolidate and capture the breadth of current research at the forefront of photonic nanocomposite materials. The selection of articles from multi-component, hybrid polymer-liquid crystal materials to nanocrystalline materials reflects different strands of research pursued in that area. Both review and research papers, covering basic and applied research topics, are presented. Photonic nanocomposite materials are generally constructed by embedding an optically functional nanosized guest material (e.g. nanoparticles, nanocrystals and molecules) into an optically transparent host matrix such as organics (e.g. (photo)polymers, polymer blends, liquid crystals) or inorganic solids (e.g. glasses and ceramics). The addition of the guest material to the host matrix can yield significant improvement and modification in their mechanical, thermal, transport and optical properties over bulk materials. As a result, high-performance photonic functionalities, with environmentally stable optical characteristics, can be achieved. In addition, nanocomposite materials can be tailor-made via the control of their linear optical properties, such as the refractive index and absorption as well as their laser, electro-optic, and nonlinear optical properties. For example, the incorporation of liquid crystalline droplets in polymers gives electrically controllable light scattering characteristics, ideally suited for display and optical switching applications. Dispersing inorganic or organic nanoparticles in optical materials leads to a strong response to incident light. Indeed, ferroelectric nanoparticles in cholesteric liquid crystals enhance the electro-optic response of the mixture. In photopolymers, nanoparticles make the formation of a high-contrast holographic grating possible, which should prove useful for applications such as optical elements and data storage. Moreover, nanoparticles dispersed in photopolymer can be assembled by light, providing the

  16. Thermally induced nonlinear optical absorption in metamaterial perfect absorbers

    SciTech Connect

    Guddala, Sriram Kumar, Raghwendra; Ramakrishna, S. Anantha

    2015-03-16

    A metamaterial perfect absorber consisting of a tri-layer (Al/ZnS/Al) metal-dielectric-metal system with top aluminium nano-disks was fabricated by laser-interference lithography and lift-off processing. The metamaterial absorber had peak resonant absorbance at 1090 nm and showed nonlinear absorption for 600ps laser pulses at 1064 nm wavelength. A nonlinear saturation of reflectance was measured to be dependent on the average laser power incident and not the peak laser intensity. The nonlinear behaviour is shown to arise from the heating due to the absorbed radiation and photo-thermal changes in the dielectric properties of aluminium. The metamaterial absorber is seen to be damage resistant at large laser intensities of 25 MW/cm{sup 2}.

  17. Thermally induced nonlinear optical absorption in metamaterial perfect absorbers

    NASA Astrophysics Data System (ADS)

    Guddala, Sriram; Kumar, Raghwendra; Ramakrishna, S. Anantha

    2015-03-01

    A metamaterial perfect absorber consisting of a tri-layer (Al/ZnS/Al) metal-dielectric-metal system with top aluminium nano-disks was fabricated by laser-interference lithography and lift-off processing. The metamaterial absorber had peak resonant absorbance at 1090 nm and showed nonlinear absorption for 600ps laser pulses at 1064 nm wavelength. A nonlinear saturation of reflectance was measured to be dependent on the average laser power incident and not the peak laser intensity. The nonlinear behaviour is shown to arise from the heating due to the absorbed radiation and photo-thermal changes in the dielectric properties of aluminium. The metamaterial absorber is seen to be damage resistant at large laser intensities of 25 MW/cm2.

  18. Alternative materials to cadmium for neutron absorbers in safeguards applications

    SciTech Connect

    Freeman, Corey R; Geist, William H; West, James D

    2009-01-01

    Cadmium is increasingly difficult to use in safeguards applications because of rising cost and increased safety regulations. This work examines the properties of two materials produced by Ceradyne, inc. that present alternatives to cadmium for neutron shielding. The first is an aluminum metal doped with boron and the second is a boron carbide powder, compressed into a ceramic. Both are enriched in the {sup 10}B isotope. Two sheets of boron doped aluminum (1.1 mm and 5.2mm thick) and one sheet of boron carbide (8.5mm thick) were provided by Ceradyne for testing. An experiment was designed to test the neutron absorption capabilities of these three sheets against two different thicknesses of cadmium (0.6mm and 1.6mm thick). The thinner piece of aluminum boron alloy (1.1mm) performed as well as the cadmium pieces at absorbing neutrons. The thicker aluminum-boron plate provided more shielding than the cadmium sheets and the boron carbide performed best by a relatively large margin. Monte Carlo N-Particle eXtended (MCNPX) transport code modeling of the experiment was performed to provide validaLed computational tools for predicting the behavior of systems in which these materials may be incorporated as alternatives to cadmium. MCNPX calculations predict that approximately 0.17mm of the boron carbide is equivalent to 0.6mm of cadmium. There are drawbacks to these materials that need to be noted when considering using them as replacements for cadmium. Notably, they may need to be thicker than cadmium, and are not malleable, requiring machining to fit any curved forms.

  19. Nanostructured thin film-based near-infrared tunable perfect absorber using phase-change material

    NASA Astrophysics Data System (ADS)

    Kocer, Hasan

    2015-01-01

    Nanostructured thin film absorbers embedded with phase-change thermochromic material can provide a large level of absorption tunability in the near-infrared region. Vanadium dioxide was employed as the phase-change material in the designed structures. The optical absorption properties of the designed structures with respect to the geometric and material parameters were systematically investigated using finite-difference time-domain computations. Absorption level of the resonance wavelength in the near-IR region was tuned from the perfect absorption level to a low level (17%) with a high positive dynamic range of near-infrared absorption intensity tunability (83%). Due to the phase transition of vanadium dioxide, the resonance at the near-infrared region is being turned on and turned off actively and reversibly under the thermal bias, thereby rendering these nanostructures suitable for infrared camouflage, emitters, and sensors.

  20. Grating-type mid-infrared light absorber based on silicon carbide material.

    PubMed

    Xue, Wenrui; Chen, Xi; Peng, Yanling; Yang, Rongcao

    2016-10-03

    A kind of grating-type mid-infrared light absorber based on silicon carbide (SiC) material is designed and its absorption properties are studied using the finite-difference frequency-domain (FDFD) method. The results show that, its absorption mechanism is the excitation of surface plasmon and magnetic polariton as well as the loss of materials. Due to the optical characteristics of the SiC material in the mid-infrared band and the truncated pyramid structure in the grating, in the range of 10.5-12.5μm and 0-80°, absorptivity of higher than 80% can be obtained with optimized structural parameters. Among six structural parameters, the layer number of the composite layers has a relatively great influence on the absorption properties, while the thickness of the dielectric layer has less influence on the absorption properties.

  1. Enhanced optical absorbance and fabrication of periodic arrays on nickel surface using nanosecond laser

    NASA Astrophysics Data System (ADS)

    Fu, Jinxiang; Liang, Hao; Zhang, Jingyuan; Wang, Yibo; Liu, Yannan; Zhang, Zhiyan; Lin, Xuechun

    2017-04-01

    A hundred-nanosecond pulsed laser was employed to structure the nickel surface. The effects of laser spatial filling interval and laser scanning speed on the optical absorbance capacity and morphologies on the nickel surface were experimentally investigated. The black nickel surface covered with dense micro/nanostructured broccoli-like clusters with strong light trapping capacity ranging from the UV to the near IR was produced at a high laser scanning speed up to v=100 mm/s. The absorbance of the black nickel is as high as 98% in the UV range of 200-400 nm, more than 97% in the visible spectrum, ranging from 400 to 800 nm, and over 90% in the IR between 800 and 2000 nm. In addition, when the nickel surface was irradiated in two-dimensional crossing scans by laser with different processing parameters, self-organized and shape-controllable structures of three-dimensional (3D) periodic arrays can be fabricated. Compared with ultrafast laser systems previously used for such processing, the nanosecond fiber laser used in this work is more cost-effective, compact and allows higher processing rates. This nickel surface structured technique may be applicable in optoelectronics, batteries industry, solar/wave absorbers, and wettability materials.

  2. Optical Materials Characterization

    DTIC Science & Technology

    1975-01-01

    cannot withstand large stress, we measure the stress- optical effect with a modified Twyman -Green interferometer , which has a sensitivity of about 0.01X...possible for us to detect the shift of 0.01 fringe in a Twyman -Green interferometer . This precision is necessary because the stress-optical effect...polycrystalline ZnSe. In the past, we have obtained the component in by measuring the shift in fringes of Twyman -Green and Fizeau interferometers as a

  3. On the physical and geometrical properties responsible for the highly absorbing nature of black materials in the infrared

    NASA Astrophysics Data System (ADS)

    Meier, Steven Robert

    Black surfaces are of paramount importance in the design of terrestrial and space-borne optical systems. Optical designers can choose from a variety of black materials to suppress reflected and scattered stray light. Among these applications are the suppression of unwanted reflection or scattering of light in optical systems, solar collectors, blackbody absorbers, thermal insulators, telescope housing and baffles where stray light reduction is vital, and cold stops and light shields for infrared detectors. The physical mechanisms responsible for understanding the highly absorbing nature of black materials in the infrared spectral region are investigated in this dissertation. We present experimental data on the optical, surface, and constituent properties of black materials. In addition, we developed unique optical instrumentation to characterize the hemispherical reflectance and scattering properties of these materials as a function of incident angle and state of polarization. We compared the experimental data to theoretical rough surface scattering models to understand the absorption mechanisms of these black materials and found good agreement. Furthermore, results from a new, highly absorbing black material in the infrared wavelength regime, known as carbon aerogels, are presented and shown to be superior or equivalent to existing black materials used by optical designers. In addition, we presented a new cylindrical-spherical cavity enclosure and calculated the apparent emissivity along the bounding surfaces of this new cavity enclosure. To our knowledge, this was the first calculation of the apparent emissivity for a cavity enclosure with obscuration. Finally, we proposed several improvements for each individual black material in order to achieve even higher absorption levels.

  4. Dysprosium titanate as an absorber material for control rods

    NASA Astrophysics Data System (ADS)

    Risovany, V. D.; Varlashova, E. E.; Suslov, D. N.

    2000-09-01

    Disprosium titanate is an attractive control rod material for the thermal neutron reactors. Its main advantages are: insignificant swelling, no out-gassing under neutron irradiation, rather high neutron efficiency, a high melting point (˜1870°C), non-interaction with the cladding at temperatures above 1000°C, simple fabrication and easily reprocessed non-radioactive waste. It can be used in control rods as pellets and powder. The disprosium titanate control rods have worked off in the MIR reactor for 17 years, in VVER-1000 - for 4 years without any operating problems. After post-irradiation examinations this type of control rod having high lifetime was recommended for the VVER and RBMK. The paper presents the examination results of absorber element dummies containing dysprosium titanate, irradiated in the SM reactor to the neutron fluence of 3.4×10 22 cm -2 ( E>0.1 MeV) and, also, the data on structure, thermal-physical properties of dysprosium titanate, efficiency of dysprosium titanate control rods.

  5. Analysis and evaluation of RF absorbing material in suppressing modes associated with a metallic cavity

    NASA Astrophysics Data System (ADS)

    Green, David L.

    Application of absorbing materials within enclosures designed to house high-speed digital electronics has become common practice for suppressing resonances associated with the enclosure geometry. Use of absorbing material is often considered toward the end of the design phase when the product is undergoing electromagnetic compatibility compliance testing, leaving little time for the additional experimentation required to optimize absorber material selection or placement within the device. The engineering principles required for maximizing absorber performance within the enclosure are often disregarded, replaced by a "shotgun" approach where multiple material options are experimented with until a solution is achieved. For this research a frequency domain reverberation chamber technique and one-port time domain quality factor estimation technique are employed to quantify the ability of various absorbing materials to suppress resonances of a physically small, electrically large cavity representative of those that may be used to enclose high-speed circuitry. Using both measurement techniques, assessment of the performance of various absorbing materials was performed as well as an evaluation of the affect absorber position has on overall material performance. It was found that both measurement techniques were effective in quantifying absorber performance within the cavity. For the frequency domain reverberation chamber approach the absorber effectiveness, defined as the difference in insertion loss between the cavity with and without absorbing material, was analyzed for various materials. For the undermoded cavity it was found that absorber effectiveness was positionally dependent. For the overmoded cavity, however, the position of the absorber within the cavity, as long as the total exposed surface area remained constant, did not have a significant impact on the absorber effectiveness. Similar results were also found by comparing the estimated quality factor for

  6. Emitter near an arbitrary body: Purcell effect, optical theorem and the Wheeler-Feynman absorber

    NASA Astrophysics Data System (ADS)

    Venkatapathi, Murugesan

    2012-09-01

    The altered spontaneous emission of an emitter near an arbitrary body can be elucidated using an energy balance of the electromagnetic field. From a classical point of view it is trivial to show that the field scattered back from any body should alter the emission of the source. But it is not at all apparent that the total radiative and non-radiative decay in an arbitrary body can add to the vacuum decay rate of the emitter (i.e.) an increase of emission that is just as much as the body absorbs and radiates in all directions. This gives us an opportunity to revisit two other elegant classical ideas of the past, the optical theorem and the Wheeler-Feynman absorber theory of radiation. It also provides us alternative perspectives of Purcell effect and generalizes many of its manifestations, both enhancement and inhibition of emission. When the optical density of states of a body or a material is difficult to resolve (in a complex geometry or a highly inhomogeneous volume) such a generalization offers new directions to solutions.

  7. Phantoms for diffuse optical imaging based on totally absorbing objects, part 2: experimental implementation

    NASA Astrophysics Data System (ADS)

    Martelli, Fabrizio; Ninni, Paola Di; Zaccanti, Giovanni; Contini, Davide; Spinelli, Lorenzo; Torricelli, Alessandro; Cubeddu, Rinaldo; Wabnitz, Heidrun; Mazurenka, Mikhail; Macdonald, Rainer; Sassaroli, Angelo; Pifferi, Antonio

    2014-07-01

    We present the experimental implementation and validation of a phantom for diffuse optical imaging based on totally absorbing objects for which, in the previous paper [J. Biomed. Opt. 18(6), 066014, (2013)], we have provided the basic theory. Totally absorbing objects have been manufactured as black polyvinyl chloride (PVC) cylinders and the phantom is a water dilution of intralipid-20% as the diffusive medium and India ink as the absorber, filled into a black scattering cell made of PVC. By means of time-domain measurements and of Monte Carlo simulations, we have shown the reliability, the accuracy, and the robustness of such a phantom in mimicking typical absorbing perturbations of diffuse optical imaging. In particular, we show that such a phantom can be used to generate any absorption perturbation by changing the volume and position of the totally absorbing inclusion.

  8. Study on metal microparticle content of the material transferred with Absorbing Film Assisted Laser Induced Forward Transfer when using silver absorbing layer

    NASA Astrophysics Data System (ADS)

    Smausz, T.; Hopp, B.; Kecskeméti, G.; Bor, Z.

    2006-04-01

    Absorbing Film Assisted Laser Induced Forward Transfer (AFA-LIFT) is a modified LIFT method where a high absorption coefficient thin film coating of a transparent substrate is used to transform the laser energy into kinetic in order to transfer the "target" material spread on it. This method can be used for the transfer of biomaterials and living cells, which could be damaged by direct irradiation of the laser beam. In previous experiments, ˜50-100 nm thick metal films have been used as absorbing layer. The transferred material can also contain metal microparticles originating from the absorbing thin film and acting as non-desired impurities in some cases. The aim of our work was to study how the properties (number, size and covered area) of metal particles transferred during the AFA-LIFT process depend on film thickness and the applied fluence. Silver thin films with different thickness (50-400 nm) were used as absorbing layers and real experimental conditions were modeled by a 100 μm thick water layer. The particles transferred without the use of water layer were also studied. The threshold laser fluence for the complete removal of the absorber from the irradiated area was found to strongly increase with increasing film thickness. The deposited micrometer and submicrometer particles were observed with optical microscope and atomic force microscope. Their size ranged from 100 nm to 20 μm and depended on the laser fluence. The increase in fluence resulted in an increasing number of particles of smaller average size.

  9. Knitted radar absorbing materials (RAM) based on nickel-cobalt magnetic materials

    NASA Astrophysics Data System (ADS)

    Teber, Ahmet; Unver, Ibrahim; Kavas, Huseyin; Aktas, Bekir; Bansal, Rajeev

    2016-05-01

    There has been a long-standing interest in the development of flexible, lightweight, thin, and reconfigurable radar absorbing materials (RAM) for military applications such as camouflaging ground-based hardware against airborne radar observation. The use of polymeric Polyacrylonitrile (PAN) fabrics as a host matrix for magnetic metal nano-particles (either at the yarn-stage or after weaving the fabric) for shielding and absorbing applications has been described in the literature. In our experimental investigation, the relative concentrations of Nickel and Cobalt as well as the coating time are varied with a view to optimizing the microwave absorption characteristics of the resulting PAN-based composite material in the radar-frequency bands (X, Ku, and K). It is found that the PAN samples with the shortest coating time have the best return losses (under -20 dB return loss over a moderate bandwidth).

  10. Materials for Optical Cryocoolers

    DTIC Science & Technology

    2013-12-07

    Melgaard, R. I . Epstein, A. Di Lieto, M. Tonelli, and M. Sheik- Bahae , “Precise determination of minimum achievable temperature for solid-state optical...M. G. Brik and K. W. Krämer, J. Lumin., 2013, 136, 221–239. 13 D. V. Seletskiy, M. P. Hehlen, R. I . Epstein and M. Sheik- Bahae , Adv. Opt... I . Epstein, Phys. Rev. Lett., 2004, 92, 24740. 16 M. Sheik- Bahae and R. I . Epstein, Nat. Photonics, 2007, 1, 693–699. 17 G. Rupper, N. H. Kwong and R

  11. Nano-Textured Fiber Coatings for Energy Absorbing Polymer Matrix Composite Materials

    DTIC Science & Technology

    2004-12-01

    NANO-TEXTURED FIBER COATINGS FOR ENERGY ABSORBING POLYMER MATRIX COMPOSITE MATERIALS R. E. Jensen and S. H. McKnight Army Research Laboratory...Textured Fiber Coatings For Energy Absorbing Polymer Matrix Composite Materials 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6

  12. Magneto-Optical Recording Materials

    NASA Astrophysics Data System (ADS)

    Gambino, Richard J.; Suzuki, Takao

    2003-05-01

    "As digital data storage technology undergoes enormous change, electrical engineers, physicists, and materials scientists need to keep pace with the materials requirements for recording media. Expert contributors -- together with world-class authorities Richard J. Gambino and Takao Suzuki -- bring you a practical, comprehensive guide to materials design and selection for magneto-optical storage media. This authoritative book explores multilayered thin films, exchanged coupled layers, materials used in current products, and materials of potential interest not yet available in practical applications. A detailed analysis concerning the physics of magneto-optical recording will help you make informed decisions about materials properties. You will also find an extensive discussion of systems and engineering design features for magneto-optical storage devices. This discussion will help you to understand how materials properties impact system performance. You will gain additional insight into this fast-developing field through in-depth coverage of these featured topics: Rare earth-transition metal amorphous alloys, multilayers, garnets, intermetallic compounds, and ferrites Basic principles of domain dynamics and recording physics Latest developments in exchange coupled layers, direct overwrite, and magnetic superresolution Minidisc, future high-density systems, and DVD format. MAGNETO-OPTICAL RECORDING MATERIALS is essential reading for anyone who needs to keep up-to-date with the latest advances in digital data storage technology."

  13. Satellite material contaminant optical properties

    NASA Technical Reports Server (NTRS)

    Wood, B. E.; Bertrand, W. T.; Seiber, B. L.; Kiech, E. L.; Falco, P. M.; Holt, J. D.

    1990-01-01

    The Air Force Wright Research and Development Center and the Arnold Engineering Development Center are continuing a program for measuring optical effects of satellite material outgassing products on cryo-optic surfaces. Presented here are infrared (4000 to 700 cm(-1)) transmittance data for contaminant films condensed on a 77 K geranium window. From the transmittance data, the contaminant film refractive and absorptive indices (n, k) were derived using an analytical thin-film interference model with a nonlinear least-squares algorithm. To date 19 materials have been studied with the optical contents determined for 13 of those. The materials include adhesives, paints, composites, films, and lubricants. This program is continuing and properties for other materials will be available in the future.

  14. Nanophase and Composite Optical Materials

    NASA Technical Reports Server (NTRS)

    2003-01-01

    This talk will focus on accomplishments, current developments, and future directions of our work on composite optical materials for microgravity science and space exploration. This research spans the order parameter from quasi-fractal structures such as sol-gels and other aggregated or porous media, to statistically random cluster media such as metal colloids, to highly ordered materials such as layered media and photonic bandgap materials. The common focus is on flexible materials that can be used to produce composite or artificial materials with superior optical properties that could not be achieved with homogeneous materials. Applications of this work to NASA exploration goals such as terraforming, biosensors, solar sails, solar cells, and vehicle health monitoring, will be discussed.

  15. All-GaInNAs ultrafast lasers: Material development for emitters and absorbers

    NASA Astrophysics Data System (ADS)

    Rutz, A.; Liverini, V.; Müller, E.; Schön, S.; Keller, U.

    2007-04-01

    Defect engineering is a key feature in material development for active and passive laser devices. Active devices such as surface emitting lasers require excellent material quality with low defect concentration and good strain management. In contrast, passive devices such as saturable absorbers benefit from nonradiative recombination via defect states. Different molecular beam epitaxy (MBE) growth conditions and annealing parameters were developed to optimize GaInNAs for both active and passive devices. We have demonstrated for the first time an all-GaInNAs modelocked vertical external-cavity surface-emitting laser (VECSEL) at 1.3 μm. We combined a GaInNAs VECSEL with a GaInNAs semiconductor saturable absorber mirror (SESAM) in a laser cavity. The VECSEL was optically pumped by an 808 nm semiconductor diode laser. The intracavity GaInNAs SESAM self-starts stable modelocking and generates a pulse duration of 18.7 ps with a pulse repetition rate of 6.1 GHz at 57 mW of average output power at a center wavelength of 1308 nm. In this paper, we briefly review the modelocking result and then focus on the MBE growth and fabrication of both active and passive GaInNAs devices.

  16. Structure, optical properties and thermal stability of Al2O3-WC nanocomposite ceramic spectrally selective solar absorbers

    NASA Astrophysics Data System (ADS)

    Gao, Xiang-Hu; Wang, Cheng-Bing; Guo, Zhi-Ming; Geng, Qing-Fen; Theiss, Wolfgang; Liu, Gang

    2016-08-01

    Traditional metal-dielectric composite coating has found important application in spectrally selective solar absorbers. However, fine metal particles can easily diffuse, congregate, or be oxidized at high temperature, which causes deterioration in the optical properties. In this work, we report a new spectrally selective solar absorber coating, composed of low Al2O3 ceramic volume fraction (Al2O3(L)-WC) layer, high Al2O3 ceramic volume fraction (Al2O3(H)-WC layer) and Al2O3 antireflection layer. The features of our work are: 1) compared with the metal-dielectric composites concept, Al2O3-WC nanocomposite ceramic successfully achieves the all-ceramic concept, which exhibits a high solar absorptance of 0.94 and a low thermal emittance of 0.08, 2) Al2O3 and WC act as filler material and host material, respectively, which are different from traditional concept, 3) Al2O3-WC nanocomposite ceramic solar absorber coating exhibits good thermal stability at 600 °C. In addition, the solar absorber coating is successfully modelled by a commercial optical simulation programme, the result of which agrees with the experimental results.

  17. Optical tomograph optimized for tumor detection inside highly absorbent organs

    NASA Astrophysics Data System (ADS)

    Boutet, Jérôme; Koenig, Anne; Hervé, Lionel; Berger, Michel; Dinten, Jean-Marc; Josserand, Véronique; Coll, Jean-Luc

    2011-05-01

    This paper presents a tomograph for small animal fluorescence imaging. The compact and cost-effective system described in this article was designed to address the problem of tumor detection inside highly absorbent heterogeneous organs, such as lungs. To validate the tomograph's ability to detect cancerous nodules inside lungs, in vivo tumor growth was studied on seven cancerous mice bearing murine mammary tumors marked with Alexa Fluor 700. They were successively imaged 10, 12, and 14 days after the primary tumor implantation. The fluorescence maps were compared over this time period. As expected, the reconstructed fluorescence increases with the tumor growth stage.

  18. Materials Discovery: Informatic Strategies for Optical Materials

    SciTech Connect

    Ferris, Kim F.; Webb-Robertson, Bobbie-Jo M.; Jones, Dumont M.

    2007-01-15

    Information-based materials discovery offers a structured method to evolve materials signatures based upon their physical properties, and to direct searches using performance-based criteria. In this current paper, we focus on the crystal structure aspects of an optical material and construct an information-based model to determine the proclivity of a particular AB composition to exhibit multiple crystal system behavior. Exploratory data methods used both supervised (support-vector machines) and unsupervised (disorder-reduction and principal-component) classification methods for structural signature development; revealing complementary valid signatures. Examination of the relative contributions of the materials chemistry descriptors within these signatures indicates a strong role for Mendeleev number chemistry which must be balanced against the cationic/anionic radius ratio and electronegativity differences of constituents within the unit cell.

  19. The role of lanthanides in optical materials

    SciTech Connect

    Weber, M.J.

    1995-05-01

    A survey is presented of the use of the lanthanides as chemical components in transmitting optical materials and as activators in materials for luminescent, electro-optic, magneto-optic, and various photosensitive applications.

  20. Magneto-optical reflectance and absorbance of PbS quantum dots

    NASA Astrophysics Data System (ADS)

    Barik, Puspendu; Singh, Akhilesh K.; Ullrich, Bruno

    2015-09-01

    Reflectance and absorbance of colloidal 2.5 nm PbS quantum dots were coincidentally measured under the presence of moderate magnetic fields below one Tesla. The work provides further insight to the optical and magneto-optical properties of quantum dots by revealing disconnect of band gap data collected in different experimental geometries and by the demonstration of reflective magneto-optical devices addressable with weak magnetic fields.

  1. Chiral monolithic absorbent constructed by optically active helical-substituted polyacetylene and graphene oxide: preparation and chiral absorption capacity.

    PubMed

    Li, Weifei; Wang, Bo; Yang, Wantai; Deng, Jianping

    2015-02-01

    Chiral monolithic absorbent is successfully constructed for the first time by using optically active helical-substituted polyacetylene and graphene oxide (GO). The preparative strategy is facile and straightforward, in which chiral-substituted acetylene monomer (Ma), cross-linker (Mb), and alkynylated GO (Mc) undergo copolymerization to form the desired monolithic absorbent in quantitative yield. The resulting monoliths are characterized by circular dichroism, UV-vis absorption, scanning electron microscopy (SEM), FT-IR, Raman, energy-dispersive spectrometer (EDS), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), XPS, and thermogravimetric analysis (TGA) techniques. The polymer chains derived from Ma form chiral helical structures and thus provide optical activity to the monoliths, while GO sheets contribute to the formation of porous structures. The porous structure enables the monolithic absorbents to demonstrate a large swelling ratio in organic solvents, and more remarkably, the helical polymer chains provide optical activity and further enantio-differentiating absorption ability. The present study establishes an efficient and versatile methodology for preparing novel functional materials, in particular monolithic chiral materials based on substituted polyacetylene and GO.

  2. Using optoacoustic imaging for measuring the temperature dependence of Grüneisen parameter in optically absorbing solutions

    PubMed Central

    Petrova, Elena; Ermilov, Sergey; Su, Richard; Nadvoretskiy, Vyacheslav; Conjusteau, André; Oraevsky, Alexander

    2013-01-01

    Grüneisen parameter is a key temperature-dependent physical characteristic responsible for thermoelastic efficiency of materials. We propose a new methodology for accurate measurements of temperature dependence of Grüneisen parameter in optically absorbing solutions. We use two-dimensional optoacoustic (OA) imaging to improve accuracy of measurements. Our approach eliminates contribution of local optical fluence and absorbance. To validate the proposed methodology, we studied temperature dependence of aqueous cupric sulfate solutions in the range from 22 to 4°C. Our results for the most diluted salt perfectly matched known temperature dependence for the Grüneisen parameter of water. We also found that Grüneisen-temperature relationship for cupric sulfate exhibits linear trend with respect to the concentration. In addition to accurate measurements of Grüneisen changes with temperature, the developed technique provides a basis for future high precision OA temperature monitoring in live tissues. PMID:24150350

  3. Optical Spectroscopy of New Materials

    NASA Technical Reports Server (NTRS)

    White, Susan M.; Arnold, James O. (Technical Monitor)

    1993-01-01

    Composites are currently used for a rapidly expanding number of applications including aircraft structures, rocket nozzles, thermal protection of spacecraft, high performance ablative surfaces, sports equipment including skis, tennis rackets and bicycles, lightweight automobile components, cutting tools, and optical-grade mirrors. Composites are formed from two or more insoluble materials to produce a material with superior properties to either component. Composites range from dispersion-hardened alloys to advanced fiber-reinforced composites. UV/VIS and FTIR spectroscopy currently is used to evaluate the bonding between the matrix and the fibers, monitor the curing process of a polymer, measure surface contamination, characterize the interphase material, monitor anion transport in polymer phases, characterize the void formation (voids must be minimized because, like cracks in a bulk material, they lead to failure), characterize the surface of the fiber component, and measure the overall optical properties for energy balances.

  4. Boron cage compound materials and composites for shielding and absorbing neutrons

    DOEpatents

    Bowen, III, Daniel E; Eastwood, Eric A

    2014-03-04

    Boron cage compound-containing materials for shielding and absorbing neutrons. The materials include BCC-containing composites and compounds. BCC-containing compounds comprise a host polymer and a BCC attached thereto. BCC-containing composites comprise a mixture of a polymer matrix and a BCC filler. The BCC-containing materials can be used to form numerous articles of manufacture for shielding and absorbing neutrons.

  5. Measurements of the light-absorbing material inside cloud droplets and its effect on cloud albedo

    NASA Technical Reports Server (NTRS)

    Twohy, C. H.; Clarke, A. D.; Warren, Stephen G.; Radke, L. F.; Charleson, R. J.

    1990-01-01

    Most of the measurements of light-absorbing aerosol particles made previously have been in non-cloudy air and therefore provide no insight into aerosol effects on cloud properties. Here, researchers describe an experiment designed to measure light absorption exclusively due to substances inside cloud droplets, compare the results to related light absorption measurements, and evaluate possible effects on the albedo of clouds. The results of this study validate those of Twomey and Cocks and show that the measured levels of light-absorbing material are negligible for the radiative properties of realistic clouds. For the measured clouds, which appear to have been moderately polluted, the amount of elemental carbon (EC) present was insufficient to affect albedo. Much higher contaminant levels or much larger droplets than those measured would be necessary to significantly alter the radiative properties. The effect of the concentrations of EC actually measured on the albedo of snow, however, would be much more pronounced since, in contrast to clouds, snowpacks are usually optically semi-infinite and have large particle sizes.

  6. Derivation of a Levelized Cost of Coating (LCOC) metric for evaluation of solar selective absorber materials

    DOE PAGES

    Ho, C. K.; Pacheco, J. E.

    2015-06-05

    A new metric, the Levelized Cost of Coating (LCOC), is derived in this paper to evaluate and compare alternative solar selective absorber coatings against a baseline coating (Pyromark 2500). In contrast to previous metrics that focused only on the optical performance of the coating, the LCOC includes costs, durability, and optical performance for more comprehensive comparisons among candidate materials. The LCOC is defined as the annualized marginal cost of the coating to produce a baseline annual thermal energy production. Costs include the cost of materials and labor for initial application and reapplication of the coating, as well as the costmore » of additional or fewer heliostats to yield the same annual thermal energy production as the baseline coating. Results show that important factors impacting the LCOC include the initial solar absorptance, thermal emittance, reapplication interval, degradation rate, reapplication cost, and downtime during reapplication. The LCOC can also be used to determine the optimal reapplication interval to minimize the levelized cost of energy production. As a result, similar methods can be applied more generally to determine the levelized cost of component for other applications and systems.« less

  7. Derivation of a Levelized Cost of Coating (LCOC) metric for evaluation of solar selective absorber materials

    SciTech Connect

    Ho, C. K.; Pacheco, J. E.

    2015-06-05

    A new metric, the Levelized Cost of Coating (LCOC), is derived in this paper to evaluate and compare alternative solar selective absorber coatings against a baseline coating (Pyromark 2500). In contrast to previous metrics that focused only on the optical performance of the coating, the LCOC includes costs, durability, and optical performance for more comprehensive comparisons among candidate materials. The LCOC is defined as the annualized marginal cost of the coating to produce a baseline annual thermal energy production. Costs include the cost of materials and labor for initial application and reapplication of the coating, as well as the cost of additional or fewer heliostats to yield the same annual thermal energy production as the baseline coating. Results show that important factors impacting the LCOC include the initial solar absorptance, thermal emittance, reapplication interval, degradation rate, reapplication cost, and downtime during reapplication. The LCOC can also be used to determine the optimal reapplication interval to minimize the levelized cost of energy production. As a result, similar methods can be applied more generally to determine the levelized cost of component for other applications and systems.

  8. Metal Hydrides as hot carrier cell absorber materials

    NASA Astrophysics Data System (ADS)

    Wang, Pei; Wen, Xiaoming; Shrestha, Santosh; Conibeer, Gavin; Aguey-Zinsou, Kondo-Francois

    2016-09-01

    The hot Carrier Solar Cell (HCSC) allows the photon-induced hot carriers (the carriers with energy larger than the band gap) to be collected before they completely thermalise. The absorber of the HCSC should have a large phononic band gap to supress Klemens Decay, which results in a slow carrier cooling speed. In fact, a large phononic band gap likely exists in a binary compound whose constituent elements have a large mass ratio between each other. Binary hydrides with their overwhelming mass ratio of the constituent elements are important absorber candidates. Study on different types of binary hydrides as potential absorber candidates is presented in this paper. Many binary transition metal hydrides have reported theoretical or experimental phonon dispersion charts which show large phononic band gaps. Among these hydrides, the titanium hydride (TiHX) is outstanding because of its low cost, easy fabrication process and is relatively inert to air and water. A TiHX thin film is fabricated by directly hydrogenating an evaporated titanium thin film. Characterisation shows good crystal quality and the hydrogenation process is believed to be successful. Ultrafast transient absorption (TA) spectroscopy is used to study the electron cooling time of TiHX. The result is very noisy due to the low absorption and transmission of the sample. The evolution of the TA curves has been explained by band to band transition using the calculated band structure of TiH2. Though not reliable due to the high noise, decay time fitting at 700nm and 600nm shows a considerably slow carrier cooling speed of the sample.

  9. Material dispersion in optical fibers.

    PubMed

    Wemple, S H

    1979-01-01

    A three-parameter description of optical fiber material dispersion is proposed which fits the available data and reveals the key roles played by bond length, lattice structure, chemical valence, average energy gap, and atomic mass. Using broadly applicable trends in electronic and phonon oscillator strengths, simple expressions are deduced for material dispersion including the zero crossover wavelength lambda(c). These results impose severe constraints on fiber design which essentially limit the possibilities for significantly improving on pure silica to sulfates (particularly Li(2)SO(4)) and to BeF(2). The predicted value of lambda(c) for the latter material is 1.05 microm.

  10. Electrically tunable metasurface perfect absorbers for ultrathin mid-infrared optical modulators.

    PubMed

    Yao, Yu; Shankar, Raji; Kats, Mikhail A; Song, Yi; Kong, Jing; Loncar, Marko; Capasso, Federico

    2014-11-12

    Dynamically reconfigurable metasurfaces open up unprecedented opportunities in applications such as high capacity communications, dynamic beam shaping, hyperspectral imaging, and adaptive optics. The realization of high performance metasurface-based devices remains a great challenge due to very limited tuning ranges and modulation depths. Here we show that a widely tunable metasurface composed of optical antennas on graphene can be incorporated into a subwavelength-thick optical cavity to create an electrically tunable perfect absorber. By switching the absorber in and out of the critical coupling condition via the gate voltage applied on graphene, a modulation depth of up to 100% can be achieved. In particular, we demonstrated ultrathin (thickness < λ0/10) high speed (up to 20 GHz) optical modulators over a broad wavelength range (5-7 μm). The operating wavelength can be scaled from the near-infrared to the terahertz by simply tailoring the metasurface and cavity dimensions.

  11. Detection of Organic Compounds in Water by an Optical Absorbance Method

    PubMed Central

    Kim, Chihoon; Eom, Joo Beom; Jung, Soyoun; Ji, Taeksoo

    2016-01-01

    This paper proposes an optical method which allows determination of the organic compound concentration in water by measurement of the UV (ultraviolet) absorption at a wavelength of 250 nm~300 nm. The UV absorbance was analyzed by means of a multiple linear regression model for estimation of the total organic carbon contents in water, which showed a close correlation with the UV absorbance, demonstrating a high adjusted coefficient of determination, 0.997. The comparison of the TOC (total organic carbon) concentrations for real samples (tab water, sea, and river) calculated from the UV absorbance spectra, and those measured by a conventional TOC analyzer indicates that the higher the TOC value the better the agreement. This UV absorbance method can be easily configured for real-time monitoring water pollution, and built into a compact system applicable to industry areas. PMID:26742043

  12. Optical design of nanowire absorbers for wavelength selective photodetectors

    PubMed Central

    Mokkapati, S.; Saxena, D.; Tan, H. H.; Jagadish, C.

    2015-01-01

    We propose the optical design for the absorptive element of photodetectors to achieve wavelength selective photo response based on resonant guided modes supported in semiconductor nanowires. We show that the waveguiding properties of nanowires result in very high absorption efficiency that can be exploited to reduce the volume of active semiconductor compared to planar photodetectors, without compromising the photocurrent. We present a design based on a group of nanowires with varying diameter for multi-color photodetectors with small footprint. We discuss the effect of a dielectric shell around the nanowires on the absorption efficiency and present a simple approach to optimize the nanowire diameter-dielectric shell thickness for maximizing the absorption efficiency. PMID:26469227

  13. Levelized Cost of Coating (LCOC) for selective absorber materials

    SciTech Connect

    Ho, Clifford K.; Pacheco, James E.

    2014-08-08

    A new metric has been developed to evaluate and compare selective absorber coatings for concentrating solar power applications. Previous metrics have typically considered the performance of the selective coating (i.e., solar absorptance and thermal emittance), but cost and durability were not considered. This report describes the development of the levelized cost of coating (LCOC), which is similar to the levelized cost of energy (LCOE) commonly used to evaluate alternative energy technologies. The LCOC is defined as the ratio of the annualized cost of the coating (and associated costs such as labor and number of heliostats required) to the average annual thermal energy produced by the receiver. The baseline LCOC using Pyromark 2500 paint was found to be %240.055/MWht, and the distribution of LCOC values relative to this baseline were determined in a probabilistic analysis to range from -%241.6/MWht to %247.3/MWht, accounting for the cost of additional (or fewer) heliostats required to yield the same baseline average annual thermal energy produced by the receiver. A stepwise multiple rank regression analysis showed that the initial solar absorptance was the most significant parameter impacting the LCOC, followed by thermal emittance, degradation rate, reapplication interval, and downtime during reapplication.

  14. 3D-Printing ‘Smarter’ Energy Absorbing Materials

    SciTech Connect

    Duoss, Eric

    2014-08-29

    Foams are, by nature, disordered materials studded with air pockets of varying sizes. Lack of control over the material’s architecture at the micrometer or nanometer scale can make it difficult to adjust the foam’s basic properties. But Eric Duoss and a team of Livermore researchers are using additive manufacturing to develop “smarter” silicone cushions. By architecting the structure at the micro scale, they are able to control macro-scale properties previously unachievable with foam materials.

  15. Coexisting oscillation modes and optical chaos in a hybrid ring cavity containing an induced absorber (CdS)

    SciTech Connect

    Wegener, M.; Klingshirn, C.

    1987-05-15

    We investigate the self-oscillations of an induced absorber (CdS, photothermal effects) in a hybrid ring cavity. If the induced absorber is intrinsically bistable, we show that for a given set of system parameters different oscillation modes may exist depending on the initial conditions. In contrast to the behavior of an intrinsically bistable absorber, we find a bifurcation route to optical chaos if the induced absorber is not intrinsically bistable.

  16. Enhancement of Optical Adaptive Sensing by Using a Dual-Stage Seesaw-Swivel Actuator with a Tunable Vibration Absorber

    PubMed Central

    Chou, Po-Chien; Lin, Yu-Cheng; Cheng, Stone

    2011-01-01

    Technological obstacles to the use of rotary-type swing arm actuators to actuate optical pickup modules in small-form-factor (SFF) disk drives stem from a hinge’s skewed actuation, subsequently inducing off-axis aberrations and deteriorating optical quality. This work describes a dual-stage seesaw-swivel actuator for optical pickup actuation. A triple-layered bimorph bender made of piezoelectric materials (PZTs) is connected to the suspension of the pickup head, while the tunable vibration absorber (TVA) unit is mounted on the seesaw swing arm to offer a balanced force to reduce vibrations in a focusing direction. Both PZT and TVA are designed to satisfy stable focusing operation operational requirements and compensate for the tilt angle or deformation of a disc. Finally, simulation results verify the performance of the dual-stage seesaw-swivel actuator, along with experimental procedures and parametric design optimization confirming the effectiveness of the proposed system. PMID:22163877

  17. Evaluation of blue and green absorbing proteorhodopsins as holographic materials.

    PubMed

    Xi, Bangwei; Tetley, William C; Marcy, Duane L; Zhong, Cheng; Whited, Gregg; Birge, Robert R; Stuart, Jeffrey A

    2008-02-28

    Transient holographic diffraction is observed for the green (GPR) and blue (BPR) absorbing proteorhodopsins (BAC31A8 and HOT75M1, respectively), as well as the GPR E108Q and BPR E110Q variants. In contrast to bacteriorhodopsin, where the metastable bR-M pair is responsible for generating diffraction, the pR and red-shifted N-like states fulfill that role in both the green and blue wild-type proteorhodopsins. The GPR E108Q and BPR E110Q variants, however, behave more similarly to their bacteriorhodopsin analogue, D96N, with diffraction arising from the PR M-state (strongly enhanced in both GPR E108Q and BPR E110Q). Of the four proteins evaluated, wild type (WT) GPR and GPR E108Q produce the highest diffraction efficiencies, etamax, at approximately 1% for a 1.7 OD sample. GPR E108Q, however, requires 1-2 orders of magnitude less laser intensity to generate eta equivalent to WT GPR and BR D96N under similar conditions (as compared to literature values). WT BPR requires lower actinic powers than GPR but diffracts only about 30% as well. BPR E110Q performs the most poorly of the four, with etamax < 0.05% for a 1.4 OD film. The Kramers-Kronig transformation and Koglenik's coupled wave theory were used to predict the dispersion spectra and diffraction efficiency for the long M-state variants. To a first approximation, the gratings formed by all samples decay upon discontinuing the 520 nm actinic beams with a time constant characteristic of the appropriate intermediate: the N-like state for WT GPR and BPR and the M-state for GPR 108Q and BPR E110Q.

  18. An Optical Characterization Technique for Parabolic Trough Solar Collectors Using Images of the Absorber Reflection

    NASA Astrophysics Data System (ADS)

    Owkes, Jeanmarie Kathleen

    As the concentrating solar power industry competes to develop a less-expensive parabolic trough collector, assurance is needed that new parabolic trough collectors maintain accurate optical alignment. Previous optical characterization techniques are either too slow, ill-suited for field testing, or do not allow the collector to be tested in realistic orientations. The Observer method presented here enables the rapid optical characterization of parabolic trough collectors in any orientation in the field. The Observer method directly measures the combined optical angular errors in the reflector surface shape and the absorber position, which can be separated into its two components: reflector surface slope and absorber misalignment. The data acquisition requires the placement of photogrammetry targets on and around the collector. Multiple photographs of the absorber and its reflection are taken with a digital camera from different angles with respect to the collector. The images are processed to determine the camera location of each image using photogrammetry bundle analysis. The absorber and its reflection are found in the photographs using image-processing techniques. A Monte Carlo uncertainty model was developed to determine the uncertainty in the Observer measurements. The uncertainty was estimated for a wide array of measurement test scenarios to demonstrate the user's control over the measurement uncertainty. To validate the Observer method, the absorber alignment technique was compared to traditional photogrammetry; the absorber position measured with the two methods compared with a root-mean-square difference of 1.5 mm in the transverse direction and 0.86 mm along the optical axis. The reflector surface slope error measurement was compared to both VSHOT and SOFAST, two well-established optical characterization tools, by measuring a single reflector panel in the laboratory. The VSHOT and SOFAST measurements agreed with the Observer with a root

  19. Method of Synthesizing a Novel Absorbent Titanosilicate Material (UPRM-5)

    NASA Technical Reports Server (NTRS)

    Hernandez-Maldonado, Arturo (Inventor); Primera-Pedrozo, Jose N (Inventor)

    2013-01-01

    A titanium silicate variant named UPRM-5 was prepared using tetraethylammonium hydroxide as a structure-directing agent (SDA). Successful detemplation was achieved via ion exchange with NH4Cl. Effective functionalization was obtained after ion exchanging the detemplated material using SrCl2 and BaCl2. Adsorption of CO2 at 25 deg C in Sr(-) and Ba-UPRM-5 materials activated at different temperatures. For low partial pressures, the observed CO2 adsorption capacities increased as follows: NH4-UPRM-5 less than Sr-UPRM-5 less than Ba-UPRM-5. Both the Sr(-) and Ba-UPRM-5 materials exhibited outstanding selectivity for CO2 over CH4, N2 and O2.

  20. Optical absorbance measurements and photoacoustic evaluation of freeze-thawed polyvinyl-alcohol vessel phantoms

    NASA Astrophysics Data System (ADS)

    Arabul, M. U.; Heres, H. M.; Rutten, M.; van de Vosse, F.; Lopata, R.

    2015-03-01

    Multispectral photoacoustic (MPA) imaging is a promising tool for the diagnosis of atherosclerotic carotids. Excitation of different constituents of a plaque with different wavelengths of the light may provide morphological information to evaluate plaque vulnerability. Preclinical validation of in vivo photoacoustic (PA) imaging requires a comprehensive phantom study. In this study, the design of optically realistic vessel phantoms for photoacoustics was examined by characterizing their optical properties for different dye concentrations, and comparing those to PA measurements. Four different concentrations of Indian ink and molecular dye were added to a 15 wt% PVA and 1 wt% orgasol mixture. Next, the homogeneously mixed gels were subjected to five freeze - thaw cycles to increase the stiffness of vessel phantoms (rinner = 2:5mm, router = 4mm). For each cycle, the optical absorbance was measured between 400 nm 990 nm using a plate reader. Additionally, photoacoustic responses of each vessel phantom at 808 nm were tested with a novel, hand-held, integrated PA probe. Measurements show that the PA signal intensity increases with the optical absorber concentration (0.3 to 0.9) in close agreement with the absorbance measurements. The freeze - thaw process has no significant effect on PA intensity. However, the total attenuation of optical energy increases after each freeze-thaw cycle, which is primarily due to the increase in the scattering coefficient. In future work, the complexity of these phantoms will be increased to examine the feasibility of distinguishing different constituents with MPA imaging.

  1. Manipulating surface plasmon waves by transformation optics: Design examples of a beam squeezer, bend, and omnidirectional absorber

    NASA Astrophysics Data System (ADS)

    Yu, Zhen-Zhong; Feng, Yi-Jun; Wang, Zheng-Bin; Zhao, Jun-Ming; Jiang, Tian

    2013-03-01

    We present several design examples of how to apply transformation optics and curved space under coordinate transformation to manipulating the surface plasmon waves in a controlled manner. We demonstrate in detail the design procedure of the plasmonic wave squeezer, in-plane bend and omnidirectional absorber. We show that the approximation method of modifying only the dielectric material of a dielectric-metal surface of the plasmonic device could lead to acceptable performance, which facilitates the fabrication of the device. The functionality of the proposed plasmonic device is verified using three-dimensional full-wave electromagnetic simulations. Aiming at practical realization, we also show the design of a plasmonic in-plane bend and omnidirectional absorber by an alternative transformation scheme, which results in a simple device structure with a tapered isotropic dielectric cladding layer on the top of the metal surface that can be fabricated with existing nanotechnology.

  2. Session: CSP Advanced Systems: Optical Materials (Presentation)

    SciTech Connect

    Kennedy, C.

    2008-04-01

    The Optical Materials project description is to characterize advanced reflector, perform accelerated and outdoor testing of commercial and experimental reflector materials, and provide industry support.

  3. Inorganic-organic solar cells based on quaternary sulfide as absorber materials.

    PubMed

    Hong, Tiantian; Liu, Zhifeng; Yan, Weiguo; Liu, Junqi; Zhang, Xueqi

    2015-12-14

    We report a novel promising quaternary sulfide (CuAgInS) to serve as a semiconductor sensitizer material in the photoelectrochemical field. In this study, CuAgInS (CAIS) sulfide sensitized ZnO nanorods were fabricated on ITO substrates through a facile and low-cost hydrothermal chemical method and applied on photoanodes for solar cells for the first time. The component and stoichiometry were key factors in determining the photoelectric performance of CAIS sulfide, which were controlled by modulating their reaction time. ZnO/Cu0.7Ag0.3InS2 nanoarrays exhibit an enhanced optical and photoelectric performance and the power conversion efficiency of ITO/ZnO/Cu0.7Ag0.3InS2/P3HT/Pt solid-state solar cell was up to 1.80%. The remarkable performance stems from improved electron transfer, a higher efficiency of light-harvesting and appropriate band gap alignment at the interface of the ZnO/Cu0.7Ag0.3InS2 NTs. The research indicates that CAIS as an absorbing material has enormous potential in solar cell systems.

  4. Electrokinetic profiles of nonowoven cotton for absorbent incontinence material

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper discusses recent work on cotton/synthetic nonwovens, their electrokinetic analysis, and their potential use in incontinence materials. Electrokinetic analysis is useful in exploring fiber surface polarity properties, and it is a useful tool to render a snap shot of the role of fiber char...

  5. Thermal and optical analysis of selective absorber coatings based on soot for applications in solar cookers

    NASA Astrophysics Data System (ADS)

    Servín, H.; Peña, M.; Sobral, H.; González, M.

    2017-01-01

    The thermal and optical properties of selective absorber coatings of a solar cooker have been investigated. Coatings have been prepared using soot from pine resin, wood stove and sugarcane, previously separated by size. Results show that the cooking power and the overall efficiency of these pots are higher than others painted with black primer. Besides, by using an integrating sphere, the diffuse reflectance of absorbers has been obtained. Lower values of the reflectance have been measured for the pots covered with soot, showing a high correlation with the results achieved from the thermal tests, considering the measurement errors.

  6. Highly Absorbing Metal Nanolaminates for Bi-Material THz Sensors

    DTIC Science & Technology

    2011-09-01

    able to penetrate most insulating materials ( textiles , paper, etc.) while reflecting from metallic objects makes it a good candidate for the leading...layers usually consist of a structural layer coated with a metal film having different coefficient of thermal expansion to that of the structural...degree angle of incidence. In order to measure the background, a gold coated silicon wafer, which behaves as a perfect mirror with reflection close to

  7. Material Activation Benchmark Experiments at the NuMI Hadron Absorber Hall in Fermilab

    SciTech Connect

    Matsumura, H.; Matsuda, N.; Kasugai, Y.; Toyoda, A.; Yashima, H.; Sekimoto, S.; Iwase, H.; Oishi, K.; Sakamoto, Y.; Nakashima, H.; Leveling, A.; Boehnlein, D.; Lauten, G.; Mokhov, N.; Vaziri, K.

    2014-06-15

    In our previous study, double and mirror symmetric activation peaks found for Al and Au arranged spatially on the back of the Hadron absorber of the NuMI beamline in Fermilab were considerably higher than those expected purely from muon-induced reactions. From material activation bench-mark experiments, we conclude that this activation is due to hadrons with energy greater than 3 GeV that had passed downstream through small gaps in the hadron absorber.

  8. Reverse-absorbance-modulation-optical lithography for optical nanopatterning at low light levels

    NASA Astrophysics Data System (ADS)

    Majumder, Apratim; Wan, Xiaowen; Masid, Farhana; Pollock, Benjamin J.; Andrew, Trisha L.; Soppera, Olivier; Menon, Rajesh

    2016-06-01

    Absorbance-Modulation-Optical Lithography (AMOL) has been previously demonstrated to be able to confine light to deep sub-wavelength dimensions and thereby, enable patterning of features beyond the diffraction limit. In AMOL, a thin photochromic layer that converts between two states via light exposure is placed on top of the photoresist layer. The long wavelength photons render the photochromic layer opaque, while the short-wavelength photons render it transparent. By simultaneously illuminating a ring-shaped spot at the long wavelength and a round spot at the short wavelength, the photochromic layer transmits only a highly confined beam at the short wavelength, which then exposes the underlying photoresist. Many photochromic molecules suffer from a giant mismatch in quantum yields for the opposing reactions such that the reaction initiated by the absorption of the short-wavelength photon is orders of magnitude more efficient than that initiated by the absorption of the long-wavelength photon. As a result, large intensities in the ring-shaped spot are required for deep sub-wavelength nanopatterning. In this article, we overcome this problem by using the long-wavelength photons to expose the photoresist, and the short-wavelength photons to confine the "exposing" beam. Thereby, we demonstrate the patterning of features as thin as λ/4.7 (137nm for λ = 647nm) using extremely low intensities (4-30 W/m2, which is 34 times lower than that required in conventional AMOL). We further apply a rigorous model to explain our experiments and discuss the scope of the reverse-AMOL process.

  9. On the use of a loudspeaker for measuring the viscoelastic properties of sound absorbing materials.

    PubMed

    Doutres, Olivier; Dauchez, Nicolas; Génevaux, Jean-Michel; Lemarquand, Guy

    2008-12-01

    This paper investigates the feasibility to use an electrodynamic loudspeaker to determine viscoelastic properties of sound-absorbing materials in the audible frequency range. The loudspeaker compresses the porous sample in a cavity, and a measurement of its electrical impedance allows one to determine the mechanical impedance of the sample: no additional sensors are required. Viscoelastic properties of the material are then estimated by inverting a 1D Biot model. The method is applied to two sound-absorbing materials (glass wool and polymer foam). Results are in good agreement with the classical compression quasistatic method.

  10. A comprehensive simulation model of the performance of photochromic films in absorbance-modulation-optical-lithography

    NASA Astrophysics Data System (ADS)

    Majumder, Apratim; Helms, Phillip L.; Andrew, Trisha L.; Menon, Rajesh

    2016-03-01

    Optical lithography is the most prevalent method of fabricating micro-and nano-scale structures in the semiconductor industry due to the fact that patterning using photons is fast, accurate and provides high throughput. However, the resolution of this technique is inherently limited by the physical phenomenon of diffraction. Absorbance-Modulation-Optical Lithography (AMOL), a recently developed technique has been successfully demonstrated to be able to circumvent this diffraction limit. AMOL employs a dual-wavelength exposure system in conjunction with spectrally selective reversible photo-transitions in thin films of photochromic molecules to achieve patterning of features with sizes beyond the far-field diffraction limit. We have developed a finite-element-method based full-electromagnetic-wave solution model that simulates the photo-chemical processes that occur within the thin film of the photochromic molecules under illumination by the exposure and confining wavelengths in AMOL. This model allows us to understand how the material characteristics influence the confinement to sub-diffraction dimensions, of the transmitted point spread function (PSF) of the exposure wavelength inside the recording medium. The model reported here provides the most comprehensive analysis of the AMOL process to-date, and the results show that the most important factors that govern the process, are the polarization of the two beams, the ratio of the intensities of the two wavelengths, the relative absorption coefficients and the concentration of the photochromic species, the thickness of the photochromic layer and the quantum yields of the photoreactions at the two wavelengths. The aim of this work is to elucidate the requirements of AMOL in successfully circumventing the far-field diffraction limit.

  11. Design and experimental verification of a perfect dual-band optical metamaterial absorber

    NASA Astrophysics Data System (ADS)

    Ye, Fenghua; Ye, Huan; Wang, Xiaozhi

    2017-03-01

    A perfect dual-band optical absorber is designed and measured. A low absorption peak (P1) and two high absorption peaks (P2 and P3) are obtained. The P1 peak is excited by the resonance of internal surface plasmon (ISP) mode. The P2 peak is resulted by the coupling of local surface plasma (LSP) modes and the resonance of ISP mode. The P3 peak is excited by the resonance of ISP mode. The damping constant of the gold film is optimization calculated in simulations. Measured results indicate that high absorption performed is obtained with different dielectric layers. The measured metamaterial absorber displays high absorption performed at TM and TE configurations. Moreover, the proposed metamaterial absorber is sensitivity on the change of the refractive index of the environmental media.

  12. Siloxane materials for optical applications

    NASA Astrophysics Data System (ADS)

    Su, Kai; DeGroot, Jon V., Jr.; Norris, Ann W.; Lo, Peter Y.

    2006-01-01

    Siloxanes, which can be viewed as hybrids of glass and organic materials, have been used to fabricate polymer waveguides and devices that exploit the large thermo-optical effect of this material. Siloxanes have many unique properties including good thermal stability, chemical resistance, tunable refractive index, tunable mechanical properties and excellent photo-stability. The refractive index of siloxane polymer is composition dependent and generally ranges from 1.4 to 1.54. Introduction of porosity or composition modification can further expand refractive index range to 1.15~1.63. The loss and absorption characteristics for a variety of silicone-based polymers are examined and an example of a UV curable polymer coating illustrates the flexibility of the silicone polymer family to be tailored to meet specific application needs.

  13. Absorber Materials for Transition-Edge Sensor X-ray Microcalorimeters

    NASA Technical Reports Server (NTRS)

    Brown, Ari-David; Bandler, Simon; Brekosky, Regis; Chervenak, James; Figueroa-Feliciano, Enectali; Finkbeiner, Fred; Sadleir, Jack; Iyomoto, Naoko; Kelley, Richard; Kilbourne, Caroline; Porter, F. Scott; Smith, Stephen; Saab, Tarek; Sadleir, Jac,

    2007-01-01

    Arrays of superconducting transition-edge sensors (TES) can provide high spatial and energy resolution necessary for x-ray astronomy. High quantum efficiency and uniformity of response can be achieved with a suitable absorber material, in which absorber x-ray stopping power, heat capacity, and thermal conductivity are relevant parameters. Here we compare these parameters for bismuth and gold. We have fabricated electroplated gold, electroplated gold/electroplated bismuth, and evaporated gold/evaporated bismuth 8x8 absorber arrays and find that a correlation exists between the residual resistance ratio (RRR) and thin film microstructure. This finding indicates that we can tailor absorber material conductivity via microstructure alteration, so as to permit absorber thermalization on timescales suitable for high energy resolution x-ray microcalorimetry. We show that by incorporating absorbers possessing large grain size, including electroplated gold and electroplated gold/electroplated bismuth, into our current Mo/Au TES, devices with tunable heat capacity and energy resolution of 2.3 eV (gold) and 2.1 eV (gold/bismuth) FWHM at 6 keV have been fabricated.

  14. Efficient graphene saturable absorbers on D-shaped optical fiber for ultrashort pulse generation

    PubMed Central

    Zapata, J. D.; Steinberg, D.; Saito, L. A. M.; de Oliveira, R. E. P.; Cárdenas, A. M.; de Souza, E. A. Thoroh

    2016-01-01

    We demonstrated a method to construct high efficiency saturable absorbers based on the evanescent light field interaction of CVD monolayer graphene deposited on side-polished D-shaped optical fiber. A set of samples was fabricated with two different core-graphene distances (0 and 1 μm), covered with graphene ranging between 10 and 25 mm length. The mode-locking was achieved and the best pulse duration was 256 fs, the shortest pulse reported in the literature with CVD monolayer graphene in EDFL. As result, we find a criterion between the polarization relative extinction ratio in the samples and the pulse duration, which relates the better mode-locking performance with the higher polarization extinction ratio of the samples. This criterion also provides a better understanding of the graphene distributed saturable absorbers and their reproducible performance as optoelectronic devices for optical applications. PMID:26856886

  15. Broad line region clouds and the absorbing material in NGC 4151

    NASA Technical Reports Server (NTRS)

    Ferland, G. J.; Mushotzky, R. F.

    1982-01-01

    A discussion is presented of the constraints imposed by X-ray, UV and optical observations on the absorbing material in the Seyfert 1.5 galaxy NGC 4151, comparing said observations with both photoionization model predictions of broad line region clouds and models of the narrow line region gas. The weakness of both semiforbidden C III 1909 and the broad component of H-alpha relative to C IV 1549, in conjunction with the absence of an absorption Balmer jump, indicate a broad line region ionization parameter that is greater in NGC 4151 than in QSO clouds by a factor of 30. The present calculations suggest that narrow line region clouds have a composition similar to extragalactic giant H II regions, with the H line spectrum showing that dust is mixed with narrow line region gas. It is hypothesized that broad line region clouds are likely to be in a radiatively driven wind, and it is shown that such clouds are opaque to radio emission.

  16. Study of earth abundant tco and absorber materials for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Prabhakar, Tejas

    In order to make photovoltaic power generation a sustainable venture, it is necessary to use cost-effective materials in the manufacture of solar cells. In this regard, AZO (Aluminum doped Zinc Oxide) and CZTS (Copper Zinc Tin Sulfide) have been studied for their application in thin film solar cells. While AZO is a transparent conducting oxide, CZTS is a photovoltaic absorber. Both AZO and CZTS consist of earth abundant elements and are non-toxic in nature. Highly transparent and conductive AZO thin films were grown using RF sputtering. The influence of deposition parameters such as working pressure, RF power, substrate temperature and flow rate on the film characteristics was investigated. The as-grown films had a high degree of preferred orientation along the (002) direction which enhanced at lower working pressures, higher RF powers and lower substrate temperatures. Williamson-Hall analysis on the films revealed that as the working pressure was increased, the nature of stress and strain gradually changed from being compressive to tensile. The fall in optical transmission of the films was a consequence of free carrier absorption resulting from enhanced carrier density due to incorporation of Al atoms or oxygen vacancies. The optical and electrical properties of the films were described well by the Burstein-Moss effect. CZTS absorber layers were grown using ultrasonic spray pyrolysis at a deposition temperature of 350 C and subsequently annealed in a sulfurization furnace. Measurements from XRD and Raman spectra confirmed the presence of pure single phase Cu2ZnSnS4. Texture analysis of as-deposited and annealed CZTS films indicated that the (112) plane which is characteristic of the kesterite phase was preferred. The grain size increased from 50 nm to 100 nm on conducting post-deposition annealing. CZTS films with stoichiometric composition yielded a band gap of 1.5 eV, which is optimal for solar energy conversion. The variation of tin in the film changed its

  17. Improving impact resistance of ceramic materials by energy absorbing surface layers

    NASA Technical Reports Server (NTRS)

    Kirchner, H. P.; Seretsky, J.

    1974-01-01

    Energy absorbing surface layers were used to improve the impact resistance of silicon nitride and silicon carbide ceramics. Low elastic modulus materials were used. In some cases, the low elastic modulus was achieved using materials that form localized microcracks as a result of thermal expansion anisotropy, thermal expansion differences between phases, or phase transformations. In other cases, semi-vitreous or vitreous materials were used. Substantial improvements in impact resistance were observed at room and elevated temperatures.

  18. Microstructural Characterization of Burnable Absorber Materials Being Evaluated for Application in LEU U-Mo Fuel Plates

    SciTech Connect

    J. F. Jue; B. Miller; B. Yao; E. Perez; Y. H. Sohn

    2011-03-01

    The starting microstructure of a fuel plate will impact how it performs during irradiation. As a result, microstructural characterization has been performed on as-fabricated monolithic fuel plates to determine the changes in fuel plate microstructure that may result from changes in fabrication parameters. Particular focus has been given to the fuel plate U-10Mo/Zr and Zr/AA6061 cladding interfaces, since the integrity of these interfaces will play a big role in determining the overall performance of the fuel plate during irradiation. In addition, burnable absorber materials for potential incorporation into monolithic fuel plates have been characterized to identify their as-fabricated microstructures. This information will be important when trying to understand the PIE data from fuel plates with burnable absorbers that are irradiated in future irradiation experiments. This paper will focus on the microstructures observed using optical metallography, X-ray diffraction, and scanning and transmission electron microscopy for monolithic fuel plates exposed to different fabrication parameters and for as-fabricated burnable absorber materials.

  19. Characterization and preparation of p(U-MMA-An) interpenetrating polymer network damping and absorbing material.

    PubMed

    Liu, Jun; Li, Qingshan; Zhuo, Yuguo; Hong, Wei; Lv, Wenfeng; Xing, Guangzhong

    2014-06-01

    P(U-MMA-ANI) interpenetrating polymer network (IPN) damping and absorbing material is successfully synthesized by PANI particles served as an absorbing agent with the microemulsion polymerization and P(U-MMA) foam IPN network structure for substrate materials with foaming way. P(U-MMA-ANI) IPN is characterized by the compression mechanical performance testing, TG-DSC, and DSC. The results verify that the P(U-MMA) IPN foam damping material has a good compressive strength and compaction cycle property, and the optimum content of PMMA was 40% (mass) with which the SEM graphs do not present the phase separation on the macro level between PMMA and PU, while the phase separation was observed on the micro level. The DTG curve indicates that because of the formation of P(U-MMA) IPN, the decomposition temperature of PMMA and the carbamate in PU increases, while that of the polyol segment in PU has almost no change. P(U-MMA-ANI) IPN foam damping and absorbing material is obtained by PANI particles served as absorbing agent in the form of filler, and PMMA in the form of micro area in substrate material. When the content of PANI was up to 2.0% (mass), the dissipation factor of composites increased, and with the increasing of frequency the dissipation factor increased in a straight line.

  20. Preparation of steel slag porous sound-absorbing material using coal powder as pore former.

    PubMed

    Sun, Peng; Guo, Zhancheng

    2015-10-01

    The aim of the study was to prepare a porous sound-absorbing material using steel slag and fly ash as the main raw material, with coal powder and sodium silicate used as a pore former and binder respectively. The influence of the experimental conditions such as the ratio of fly ash, sintering temperature, sintering time, and porosity regulation on the performance of the porous sound-absorbing material was investigated. The results showed that the specimens prepared by this method had high sound absorption performance and good mechanical properties, and the noise reduction coefficient and compressive strength could reach 0.50 and 6.5MPa, respectively. The compressive strength increased when the dosage of fly ash and sintering temperature were raised. The noise reduction coefficient decreased with increasing ratio of fly ash and reducing pore former, and first increased and then decreased with the increase of sintering temperature and time. The optimum preparation conditions for the porous sound-absorbing material were a proportion of fly ash of 50% (wt.%), percentage of coal powder of 30% (wt.%), sintering temperature of 1130°C, and sintering time of 6.0hr, which were determined by analyzing the properties of the sound-absorbing material.

  1. Models for the optical simulations of fractal aggregated soot particles thinly coated with non-absorbing aerosols

    NASA Astrophysics Data System (ADS)

    Wu, Yu; Cheng, Tianhai; Zheng, Lijuan; Chen, Hao

    2016-10-01

    Light absorption enhancement of aged soot aerosols is highly sensitive to the morphologies and mixing states of soot aggregates and their non-absorbing coatings, such as organic materials. The quantification of these effects on the optical properties of thinly coated soot aerosols is simulated using an effective model with fixed volume fractions. Fractal aggregated soot was simulated using the diffusion limited aggregation (DLA) algorithm and discretized into soot dipoles. The dipoles of non-absorbing aerosols, whose number was fixed by the volume fraction, were further generated from the neighboring random edge dipoles. Their optical properties were calculated using the discrete dipole approximation (DDA) method and were compared with other commonly used models. The optical properties of thinly coated soot calculated using the fixed volume fraction model are close to (less than ~10% difference) the results of the fixed coating thickness model, except their asymmetry parameters (up to ~25% difference). In the optical simulations of thinly coated soot aerosols, this relative difference of asymmetry parameters and phase functions between these realistic models may be notable. The realizations of the fixed volume fraction model may introduce smaller variation of optical results than those of the fixed coating thickness model. Moreover, the core-shell monomers model and homogeneous aggregated spheres model with the Maxwell-Garnett (MG) theory may underestimate (up to ~20%) the cross sections of thinly coated soot aggregates. The single core-shell sphere model may largely overestimate (up to ~150%) the cross sections and single scattering albedo of thinly coated soot aggregates, and it underestimated (up to ~60%) their asymmetry parameters. It is suggested that the widely used single core-shell sphere approximation may not be suitable for the single scattering calculations of thinly coated soot aerosols.

  2. Absorbent Material

    NASA Technical Reports Server (NTRS)

    1985-01-01

    A superabsorbent fabric developed by Johnson Space Center and described in Tech Briefs was adapted by Honeywell and fabricated into special containment devices used on Navy "smart" torpedos. The superabsorbent fabric can sequester up to 400 times its own weight in water and protects the torpedo electronic controls from possible short circuiting by deepwater hull seepage.

  3. Self-stabilizing optical clock pulse-train generator using SOA and saturable absorber for asynchronous optical packet processing.

    PubMed

    Nakahara, Tatsushi; Takahashi, Ryo

    2013-05-06

    We propose a novel, self-stabilizing optical clock pulse-train generator for processing preamble-free, asynchronous optical packets with variable lengths. The generator is based on an optical loop that includes a semiconductor optical amplifier (SOA) and a high-extinction spin-polarized saturable absorber (SA), with the loop being self-stabilized by balancing out the gain and absorption provided by the SOA and SA, respectively. The optical pulse train is generated by tapping out a small portion of a circulating seed pulse. The convergence of the generated pulse energy is enabled by the loop round-trip gain function that has a negative slope due to gain saturation in the SOA. The amplified spontaneous emission (ASE) of the SOA is effectively suppressed by the SA, and a backward optical pulse launched into the SOA enables overcoming the carrier-recovery speed mismatch between the SOA and SA. Without external control for the loop gain, a stable optical pulse train consisting of more than 50 pulses with low jitter is generated from a single 10-ps seed optical pulse even with a variation of 10 dB in the seed pulse intensity.

  4. Clinical studies with disposable diapers containing absorbent gelling materials: evaluation of effects on infant skin condition.

    PubMed

    Campbell, R L; Seymour, J L; Stone, L C; Milligan, M C

    1987-12-01

    Disposable infant diapers with absorbent gelling material (cross-linked sodium polyacrylates) incorporated into the core were clinically evaluated for their effect on infant skin condition. Absorbent gelling materials tightly hold water and provide pH control by a buffering capacity as well as by helping to segregate urine apart from feces. Four clinical studies were conducted with each following a rigid protocol that controlled for variables of diet and age in addition to the diaper material that may influence the development of diaper dermatitis and helped to control for any inherent bias in the study. This allowed for the controlled assessment of skin condition with respect to diaper type. Absorbent gelling material-containing disposable, conventional (100% cellulose core) disposable, and home-laundered cloth diapers were test products. In these studies 1614 infants were initially enrolled with 522 of them assigned to absorbent gelling material disposable, 738 to conventional disposable, and 354 to home-laundered cloth diapers. Objective measurements of skin wetness (transepidermal water loss) and skin pH, as well as double-blind grading of diaper dermatitis, were the measures of skin condition. Absorbent gelling material disposable diapers were associated with significantly reduced skin wetness, closer to normal skin pH, and lower degrees of diaper dermatitis when compared to conventional disposable or home-laundered cloth diapers. The results are consistent with the hypothesis that better control in the diaper area of skin wetness, skin pH, and the prevention of the mixing of urine and feces produces a better diaper environment.

  5. Near-ideal optical metamaterial absorbers with super-octave bandwidth.

    PubMed

    Bossard, Jeremy A; Lin, Lan; Yun, Seokho; Liu, Liu; Werner, Douglas H; Mayer, Theresa S

    2014-02-25

    Nanostructured optical coatings with tailored spectral absorption properties are of interest for a wide range of applications such as spectroscopy, emissivity control, and solar energy harvesting. Optical metamaterial absorbers have been demonstrated with a variety of customized single band, multiple band, polarization, and angular configurations. However, metamaterials that provide near unity absorptivity with super-octave bandwidth over a specified optical wavelength range have not yet been demonstrated experimentally. Here, we show a broadband, polarization-insensitive metamaterial with greater than 98% measured average absorptivity that is maintained over a wide ± 45° field-of-view for mid-infrared wavelengths between 1.77 and 4.81 μm. The nearly ideal absorption is realized by using a genetic algorithm to identify the geometry of a single-layer metal nanostructure array that excites multiple overlapping electric resonances with high optical loss across greater than an octave bandwidth. The response is optimized by substituting palladium for gold to increase the infrared metallic loss and by introducing a dielectric superstrate to suppress reflection over the entire band. This demonstration advances the state-of-the-art in high-performance broadband metamaterial absorbers that can be reliably fabricated using a single patterned layer of metal nanostructures.

  6. Food-processes wastewaters treatment using food solid-waste materials as adsorbents or absorbents

    NASA Astrophysics Data System (ADS)

    Rapti, Ilaira; Georgopoulos, Stavros; Antonopoulou, Maria; Konstantinou, Ioannis; Papadaki, Maria

    2016-04-01

    The wastewaters generated by olive-mills during the production of olive oil, wastewaters from a dairy and a cow-farm unit and wastewaters from a small food factory have been treated by means of selected materials, either by-products of the same units, or other solid waste, as absorbents or adsorbents in order to identify the capacity of those materials to remove organic load and toxicity from the aforementioned wastewaters. The potential of both the materials used as absorbents as well as the treated wastewaters to be further used either as fertilizers or for agricultural irrigation purposes are examined. Dry olive leaves, sheep wool, rice husks, etc. were used either in a fixed-bed or in a stirred batch arrangemen,t employing different initial concentrations of the aforementioned wastewaters. The efficiency of removal was assessed using scpectrophotometric methods and allium test phytotoxicity measurements. In this presentation the response of each material employed is shown as a function of absorbent/adsorbent quantity and kind, treatment time and wastewater kind and initial organic load. Preliminary results on the potential uses of the adsorbents/absorbents and the treated wastewaters are also shown. Keywords: Olive-mill wastewaters, dairy farm wastewaters, olive leaves, zeolite, sheep wool

  7. New Insight into the Angle Insensitivity of Ultrathin Planar Optical Absorbers for Broadband Solar Energy Harvesting.

    PubMed

    Liu, Dong; Yu, Haitong; Duan, Yuanyuan; Li, Qiang; Xuan, Yimin

    2016-09-01

    Two challenging problems still remain for optical absorbers consisting of an ultrathin planar semiconductor film on top of an opaque metallic substrate. One is the angle-insensitive mechanism and the other is the system design needed for broadband solar energy harvesting. Here, first we theoretically demonstrates that the high refractive index, instead of the ultrathin feature as reported in previous studies, is the physical origin of the angle insensitivity for ultrathin planar optical absorbers. They exhibit omnidirectional resonance for TE polarization due to the high complex refractive index difference between the semiconductor and the air, while for TM polarization the angle insensitivity persists up to an incident angle related to the semiconductor refractive index. These findings were validated by fabricating and characterizing an 18 nm Ge/Ag absorber sample (representative of small band gap semiconductors for photovoltaic applications) and a 22 nm hematite/Ag sample (representative of large band gap semiconductors for photoelectrochemical applications). Then, we took advantage of angle insensitivity and designed a spectrum splitting configuration for broadband solar energy harvesting. The cascaded solar cell and unassisted solar water splitting systems have photovoltaic and photoelectrochemical cells that are also spectrum splitters, so an external spectrum splitting element is not needed.

  8. New Insight into the Angle Insensitivity of Ultrathin Planar Optical Absorbers for Broadband Solar Energy Harvesting

    PubMed Central

    Liu, Dong; Yu, Haitong; Duan, Yuanyuan; Li, Qiang; Xuan, Yimin

    2016-01-01

    Two challenging problems still remain for optical absorbers consisting of an ultrathin planar semiconductor film on top of an opaque metallic substrate. One is the angle-insensitive mechanism and the other is the system design needed for broadband solar energy harvesting. Here, first we theoretically demonstrates that the high refractive index, instead of the ultrathin feature as reported in previous studies, is the physical origin of the angle insensitivity for ultrathin planar optical absorbers. They exhibit omnidirectional resonance for TE polarization due to the high complex refractive index difference between the semiconductor and the air, while for TM polarization the angle insensitivity persists up to an incident angle related to the semiconductor refractive index. These findings were validated by fabricating and characterizing an 18 nm Ge/Ag absorber sample (representative of small band gap semiconductors for photovoltaic applications) and a 22 nm hematite/Ag sample (representative of large band gap semiconductors for photoelectrochemical applications). Then, we took advantage of angle insensitivity and designed a spectrum splitting configuration for broadband solar energy harvesting. The cascaded solar cell and unassisted solar water splitting systems have photovoltaic and photoelectrochemical cells that are also spectrum splitters, so an external spectrum splitting element is not needed. PMID:27582317

  9. Point-by-point near-field optical energy deposition around plasmonic nanospheres in absorbing media.

    PubMed

    Harrison, R K; Ben-Yakar, Adela

    2015-08-01

    Here we investigate the effects of absorbing media on plasmon-enhanced near-field optical energy deposition. We find that increasing absorption by the medium results in increased particle scattering at the expense of particle absorption, and that much of this increased particle scattering is absorbed by the medium close to the particle surface. We present an analytical method for evaluating the spatial distribution of near-field enhanced absorption surrounding plasmonic metal nanospheres in absorbing media using a new point-by-point method. We propose criteria to define relevant near-field boundaries and calculate the properties of the local absorption enhancement, which redistributes absorption to the near-field and decays asymptotically as a function of the distance from the particle to background levels. Using this method, we performed a large-scale parametric study to understand the effect of particle size and wavelength on the near-field absorption for gold nanoparticles in aqueous media and silicon, and identified conditions that are relevant to enhanced local infrared absorption in silicon. The presented approach provides insight into the local energy transfer around plasmonic nanoparticles for predicting near-field effects for advanced concepts in optical sensing, thin-film solar cells, nonlinear imaging, and photochemical applications.

  10. New Insight into the Angle Insensitivity of Ultrathin Planar Optical Absorbers for Broadband Solar Energy Harvesting

    NASA Astrophysics Data System (ADS)

    Liu, Dong; Yu, Haitong; Duan, Yuanyuan; Li, Qiang; Xuan, Yimin

    2016-09-01

    Two challenging problems still remain for optical absorbers consisting of an ultrathin planar semiconductor film on top of an opaque metallic substrate. One is the angle-insensitive mechanism and the other is the system design needed for broadband solar energy harvesting. Here, first we theoretically demonstrates that the high refractive index, instead of the ultrathin feature as reported in previous studies, is the physical origin of the angle insensitivity for ultrathin planar optical absorbers. They exhibit omnidirectional resonance for TE polarization due to the high complex refractive index difference between the semiconductor and the air, while for TM polarization the angle insensitivity persists up to an incident angle related to the semiconductor refractive index. These findings were validated by fabricating and characterizing an 18 nm Ge/Ag absorber sample (representative of small band gap semiconductors for photovoltaic applications) and a 22 nm hematite/Ag sample (representative of large band gap semiconductors for photoelectrochemical applications). Then, we took advantage of angle insensitivity and designed a spectrum splitting configuration for broadband solar energy harvesting. The cascaded solar cell and unassisted solar water splitting systems have photovoltaic and photoelectrochemical cells that are also spectrum splitters, so an external spectrum splitting element is not needed.

  11. Phantoms for diffuse optical imaging based on totally absorbing objects, part 1: Basic concepts.

    PubMed

    Martelli, Fabrizio; Pifferi, Antonio; Contini, Davide; Spinelli, Lorenzo; Torricelli, Alessandro; Wabnitz, Heidrun; Macdonald, Rainer; Sassaroli, Angelo; Zaccanti, Giovanni

    2013-06-01

    The design of inhomogeneous phantoms for diffuse optical imaging purposes using totally absorbing objects embedded in a diffusive medium is proposed and validated. From time-resolved and continuous-wave Monte Carlo simulations, it is shown that a given or desired perturbation strength caused by a realistic absorbing inhomogeneity of a certain absorption and volume can be approximately mimicked by a small totally absorbing object of a so-called equivalent black volume (equivalence relation). This concept can be useful in two ways. First, it can be exploited to design realistic inhomogeneous phantoms with different perturbation strengths simply using a set of black objects with different volumes. Further, it permits one to grade physiological or pathological changes on a reproducible scale of perturbation strengths given as equivalent black volumes, thus facilitating the performance assessment of clinical instruments. A set of plots and interpolating functions to derive the equivalent black volume corresponding to a given absorption change is provided. The application of the equivalent black volume concept for grading different optical perturbations is demonstrated for some examples.

  12. Realizing thin electromagnetic absorbers for wide incidence angles from commercially available planar circuit materials

    SciTech Connect

    Glover, Brian B; Whites, Kieth W; Radway, Matthew J

    2009-01-01

    In this study, recent work on engineering R-card surface resistivity with printed metallic patterns is extended to the design of thin electromagnetic absorbers. Thin electromagnetic absorbers for wide incidence angles and both polarizations have recently been computationally verified by Luukkonen et al.. These absorbers are analytically modeled high-impedance surfaces with capacitive arrays of square patches implemented with relatively high dielectric constant and high loss substrate. However, the advantages provided by the accurate analytical model are largely negated by the need to obtain high dielectric constant material with accurately engineered loss. Fig. I(c) illustrates full-wave computational results for an absorber without vias engineered as proposed by Luukkonen et al.. Unique values for the dielectric loss are required for different center frequencies. Parameters for the capacitive grid are D=5.0 mm and w=O.l mm for a center frequency of 3.36 GHz. The relative permittivity and thickness is 9.20(1-j0.234) and 1=3.048 mm. Consider a center frequency of5.81 GHz and again 1=3.048 mm, the required parameters for the capacitive grid are D=2.0 mm and w=0.2 mm where the required relative permittivity is now 9.20(1-j0.371) Admittedly, engineered dielectrics are themselves a historically interesting and fruitful research area which benefits today from advances in monolithic fabrication using direct-write of dielectrics with nanometer scale inclusions. However, our objective in the present study is to realize the advantages of the absorber proposed by Luukkonen et al. without resort to engineered lossy dielectrics. Specifically we are restricted to commercially available planer circuit materials without use of in-house direct-write technology or materials engineering capability. The materials considered here are TMM 10 laminate with (35 {mu}lm copper cladding with a complex permittivity 9.20-j0.0022) and Ohmegaply resistor conductor material (maximum 250 {Omega

  13. Study of optical absorbance in porous silicon nanowires for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Charrier, Joël; Najar, Adel; Pirasteh, Parastesh

    2013-10-01

    Porous silicon nanowires (PSiNWs) layers fabrication was reported. Reflectance spectra were measured as a function of the nanowire length and were inferior to 0.1% and a strong photoluminescence (PL) signal was measured from samples. Models based on cone shape of nanowires located in circular and rectangular bases were used to calculate the reflectance using the transfer matrix formalism (TMF) of PSiNWs layer. The modeling of the reflectance permits to explain this value by taking account into the shape of the nanowires and its porosity. Optical absorbance and transmission were also theoretically studied. The absorbance was superior to that obtained with silicon nanowires and the ultimate efficiency was about equal to 25% for normal incidence angle. These results could be applied to the potential application in low-cost and high efficiency PSiNWs based solar cells.

  14. Oriented free-standing ammonium vanadium oxide nanobelt membranes: highly selective absorbent materials.

    PubMed

    Zou, Rujia; Zhang, Zhenyu; Yu, Li; Tian, Qiwei; Wu, Jianghong; Sun, Yangang; Chen, Zhigang; Hu, Junqing

    2010-12-27

    Highly selective, absorbent, free-standing, paper-like membranes made of ammonium vanadium oxide (NH(4)V(4)O(14)) nanobelts have been engineered by taking advantage of the nanoscaled self-assembly of architectures that display a mesh structure with an average periodic pore size of about 5 to 10 nm. The NH(4)V(4)O(14) nanobelts are synthesized by using a simple hydrothermal process, and exhibit the same orientation and assemble into bundles, each about 40 to 80 nm in width, 3 to 5 nm in thickness, and up to several millimeters in length. Importantly, the as-obtained NH(4)V(4)O(14) nanobelt membranes can highly selectively absorb a variety of organic solvents, covering both polar and non-polar solvents, for example, the absorbent capacity of glycol is 28 times as high as the initial weight of the membrane, and it can even separate organic solvents with similar polarities and absorb solid contaminants in organic solvents. These highly selective, absorbent membrane materials can be an ideal candidate for the separation and removal of pollution in industrial and environmental applications.

  15. Plasmonic materials based on ZnO films and their potential for developing broadband middle-infrared absorbers

    SciTech Connect

    Kesim, Yunus E. Battal, Enes; Okyay, Ali K.

    2014-07-15

    Noble metals such as gold and silver have been extensively used for plasmonic applications due to their ability to support plasmons, yet they suffer from high intrinsic losses. Alternative plasmonic materials that offer low loss and tunability are desired for a new generation of efficient and agile devices. In this paper, atomic layer deposition (ALD) grown ZnO is investigated as a candidate material for plasmonic applications. Optical constants of ZnO are investigated along with figures of merit pertaining to plasmonic waveguides. We show that ZnO can alleviate the trade-off between propagation length and mode confinement width owing to tunable dielectric properties. In order to demonstrate plasmonic resonances, we simulate a grating structure and computationally demonstrate an ultra-wide-band (4–15 μm) infrared absorber.

  16. Research and application of kapok fiber as an absorbing material: a mini review.

    PubMed

    Zheng, Yian; Wang, Jintao; Zhu, Yongfeng; Wang, Aiqin

    2015-01-01

    Kapok fiber corresponds to the seed hairs of the kapok tree (Ceiba pentandra), and is a typical cellulosic fiber with the features of thin cell wall, large lumen, low density and hydrophobic-oleophilic properties. As a type of renewable natural plant fiber, kapok fiber is abundant, biocompatible and biodegradable, and its full exploration and potential application have received increasing attention in both academic and industrial fields. Based on the structure and properties of kapok fiber, this review provides a summary of recent research on kapok fiber including chemical and physical treatments, kapok fiber-based composite materials, and the application of kapok fiber as an absorbent material for oils, metal ions, dyes, and sound, with special attention to its use as an oil-absorbing material, one predominant application of kapok fiber in the coming future.

  17. Evaluation of Aluminum-Boron Carbide Neutron Absorbing Materials for Interim Storage of Used Nuclear Fuel

    SciTech Connect

    Wang, Lumin; Wierschke, Jonathan Brett

    2015-04-08

    The objective of this work was to understand the corrosion behavior of Boral® and Bortec® neutron absorbers over long-term deployment in a used nuclear fuel dry cask storage environment. Corrosion effects were accelerated by flowing humidified argon through an autoclave at temperatures up to 570°C. Test results show little corrosion of the aluminum matrix but that boron is leaching out of the samples. Initial tests performed at 400 and 570°C were hampered by reduced flow caused by the rapid build-up of solid deposits in the outlet lines. Analysis of the deposits by XRD shows that the deposits are comprised of boron trioxide and sassolite (H3BO3). The collection of boron- containing compounds in the outlet lines indicated that boron was being released from the samples. Observation of the exposed samples using SEM and optical microscopy show the growth of new phases in the samples. These phases were most prominent in Bortec® samples exposed at 570°C. Samples of Boral® exposed at 570°C showed minimal new phase formation but showed nearly the complete loss of boron carbide particles. Boron carbide loss was also significant in Boral samples at 400°C. However, at 400°C phases similar to those found in Bortec® were observed. The rapid loss of the boron carbide particles in the Boral® is suspected to inhibit the formation of the new secondary phases. However, Material samples in an actual dry cask environment would be exposed to temperatures closer to 300°C and less water than the lowest test. The results from this study conclude that at the temperature and humidity levels present in a dry cask environment, corrosion and boron leaching will have no effect on the performance of Boral® and Bortec® to maintain criticality control.

  18. Polymeric Materials for Electro-Optic Testing.

    DTIC Science & Technology

    1987-07-01

    what Langmuir Blodgett films are, how they are grown and deposited on a material, and the electro - optic effects in Langmuir/Blodgett films. Stephen...Kowel has experimented with several different types of organic dyes mixed in the films to increase the electro - optic effect in the films. The bulk of his...test integrated circuits. Keywords: Langmuir Blodgett films, Electro - optic testing, Integrated circuits, Linear electro - optic effect.

  19. Laser ablation of absorbing liquids under transparent cover: acoustical and optical monitoring

    NASA Astrophysics Data System (ADS)

    Samokhin, A. A.; Il'ichev, N. N.; Pivovarov, P. A.; Sidorin, A. V.

    2016-06-01

    Phase transition induced with infrared (λ = 2920 nm and λ = 2940 nm) nanosecond laser pulses in strongly absorbing liquids (water, ethanol) under transparent solid cover is investigated with the help of acoustical and optical monitoring. LiNbO3 transducer is used for registration of pressure pulses generated in irradiated liquids. Optical signals due to scattering and specular reflection of probing optical beams are explored with the schemes involving total internal reflection and interference effects. Combination of these two optical diagnostic methods permits for the first time to show that irradiation of covered liquids leads to vapor cavity formation which is divided from the cover with thin (submicron) liquid film despite the fact that radiation intensity maximum is located just at the liquid-plate boundary. The cavity formation is due to explosive boiling which occurs when the superheated liquid reaches its superheating limit in near critical region. After the first acoustical signal, the second signal is observed with several hundreds microseconds time delay which is caused by the vapor cavity collapse. Some results of optical and acoustical diagnostics in the case of free liquid surface are also presented.

  20. Absorbable or nonabsorbable suture materials for closure of the dura mater?

    PubMed

    Vällfors, B; Hansson, H A; Svensson, J

    1981-10-01

    This study was undertaken to determine which suture material would give the best results for closure of the dura mater. Because there is no need for the suture to remain longer than until healing has occurred and as remaining foreign material will predispose to foreign body reactions and infection, it was considered important to test new absorbable materials like polyglactin 910 (Vicryl) and polyglycolic acid (Dexon) for closure of the dura mater. The reactions from these materials were compared to those of silk and polyester (Ethibond) in dogs 60 days after the suture of dural incisions. The quality of healing with respect to the smoothness of the subdural surface, the presence of adhesions between sutures and the brain surface, the degree of absorption of the material, and reactions around the sutures were evaluated. Vicryl gave the best results, providing a smooth subdural surface without adhesions. It was almost totally absorbed when healing was completed, in contrast to Dexon and the other materials. The cellular reaction around Vicryl was slight. Silk, Ethibond, and Dexon protruded from the subdural surface and adhesions to the arachnoid were common. When the dura mater was removed, these adhesions tore off the leptomeninges with their vascular supply to the cortex. The results of these experiments seem to justify the recommendation of Vicryl for suturing of the dura mater. Such an absorbable material decreases the risk of foreign body reactions, and infections will be more easily combated because of the absence of foreign material. The lack of subdural adhesions is an advantage if reoperation is necessary.

  1. A fibre optic scintillator dosemeter for absorbed dose measurements of low-energy X-ray-emitting brachytherapy sources.

    PubMed

    Sliski, Alan; Soares, Christopher; Mitch, Michael G

    2006-01-01

    A newly developed dosemeter using a 0.5 mm diameter x 0.5 mm thick cylindrical plastic scintillator coupled to the end of a fibre optic cable is capable of measuring the absorbed dose rate in water around low-activity, low-energy X-ray emitters typically used in prostate brachytherapy. Recent tests of this dosemeter showed that it is possible to measure the dose rate as a function of distance in water from 2 to 30 mm of a (103)Pd source of air-kerma strength 3.4 U (1 U = 1 microGy m(2) h(-1)), or 97 MBq (2.6 mCi) apparent activity, with good signal-to-noise ratio. The signal-to-noise ratio is only dependent on the integration time and background subtraction. The detector volume is enclosed in optically opaque, nearly water-equivalent materials so that there is no polar response other than that due to the shape of the scintillator volume chosen, in this case cylindrical. The absorbed dose rate very close to commercial brachytherapy sources can be mapped in an automated water phantom, providing a 3-D dose distribution with sub-millimeter spatial resolution. The sensitive volume of the detector is 0.5 mm from the end of the optically opaque waterproof housing, enabling measurements at very close distances to sources. The sensitive detector electronics allow the measurement of very low dose rates, as exist at centimeter distances from these sources. The detector is also applicable to mapping dose distributions from more complex source geometries such as eye applicators for treating macular degeneration.

  2. Evaluations of diapers containing absorbent gelling material with conventional disposable diapers in newborn infants.

    PubMed

    Lane, A T; Rehder, P A; Helm, K

    1990-03-01

    We evaluated 149 infants diapered in either conventional cellulose core disposable diapers or diapers containing cellulose core with absorbent gelling material. The infants were evaluated from 1 day of age to 14 weeks of age for the prevalence and severity of diaper dermatitis. We identified a low prevalence of diaper dermatitis throughout the study period. At 14 weeks of age, we noted that infants in diapers containing absorbent gelling material had significantly less diaper dermatitis than those in conventional disposable diapers. Despite the overall low prevalence of diaper dermatitis in the newborn period, 7 of 204 infants evaluated had small skin erosions in the diaper area noted within the first 4 days of age. Both diaper types were associated with infants with erosions. This surprisingly high incidence of erosions in newborn infants suggests previously undocumented increased skin fragility of full-term infants.

  3. A novel quaternary solid solution photo-absorber material for photoelectrochemical hydrogen generation.

    PubMed

    Hong, Tiantian; Liu, Zhifeng; Yan, Weiguo; Wang, Bo; Zhang, Xueqi; Liu, Junqi; Wang, Junkai; Han, Jianhua

    2015-09-14

    We report a novel quaternary solid solution (Ag-Cu-Sb-S or ACSS) serving as a photo-absorber material in the photoelectrochemical field for the first time, and ZnO/ACSS nanoarrays exhibited a photocurrent density of 4.45 mA cm(-2). The research indicates that ZnO/ACSS composite structures have enormous potential in PEC hydrogen generation systems.

  4. Optical properties and aging of light-absorbing secondary organic aerosol

    DOE PAGES

    Liu, Jiumeng; Lin, Peng; Laskin, Alexander; ...

    2016-10-14

    The light-absorbing organic aerosol (OA) commonly referred to as “brown carbon” (BrC) has attracted considerable attention in recent years because of its potential to affect atmospheric radiation balance, especially in the ultraviolet region and thus impact photochemical processes. A growing amount of data has indicated that BrC is prevalent in the atmosphere, which has motivated numerous laboratory and field studies; however, our understanding of the relationship between the chemical composition and optical properties of BrC remains limited. We conducted chamber experiments to investigate the effect of various volatile organic carbon (VOC) precursors, NOx concentrations, photolysis time, and relative humidity (RH) on the light absorptionmore » of selected secondary organic aerosols (SOA). Light absorption of chamber-generated SOA samples, especially aromatic SOA, was found to increase with NOx concentration, at moderate RH, and for the shortest photolysis aging times. The highest mass absorption coefficient (MAC) value is observed from toluene SOA products formed under high-NOx conditions at moderate RH, in which nitro-aromatics were previously identified as the major light-absorbing compounds. BrC light absorption is observed to decrease with photolysis time, correlated with a decline of the organic nitrate fraction of SOA. SOA formed from mixtures of aromatics and isoprene absorb less visible (Vis) and ultraviolet (UV) light than SOA formed from aromatic precursors alone on a mass basis. However, the mixed SOA absorption was underestimated when optical properties were predicted using a two-product SOA formation model, as done in many current climate models. Further investigation, including analysis on detailed mechanisms, are required to explain the discrepancy.« less

  5. Optical properties and aging of light-absorbing secondary organic aerosol

    NASA Astrophysics Data System (ADS)

    Liu, Jiumeng; Lin, Peng; Laskin, Alexander; Laskin, Julia; Kathmann, Shawn M.; Wise, Matthew; Caylor, Ryan; Imholt, Felisha; Selimovic, Vanessa; Shilling, John E.

    2016-10-01

    The light-absorbing organic aerosol (OA) commonly referred to as "brown carbon" (BrC) has attracted considerable attention in recent years because of its potential to affect atmospheric radiation balance, especially in the ultraviolet region and thus impact photochemical processes. A growing amount of data has indicated that BrC is prevalent in the atmosphere, which has motivated numerous laboratory and field studies; however, our understanding of the relationship between the chemical composition and optical properties of BrC remains limited. We conducted chamber experiments to investigate the effect of various volatile organic carbon (VOC) precursors, NOx concentrations, photolysis time, and relative humidity (RH) on the light absorption of selected secondary organic aerosols (SOA). Light absorption of chamber-generated SOA samples, especially aromatic SOA, was found to increase with NOx concentration, at moderate RH, and for the shortest photolysis aging times. The highest mass absorption coefficient (MAC) value is observed from toluene SOA products formed under high-NOx conditions at moderate RH, in which nitro-aromatics were previously identified as the major light-absorbing compounds. BrC light absorption is observed to decrease with photolysis time, correlated with a decline of the organic nitrate fraction of SOA. SOA formed from mixtures of aromatics and isoprene absorb less visible (Vis) and ultraviolet (UV) light than SOA formed from aromatic precursors alone on a mass basis. However, the mixed SOA absorption was underestimated when optical properties were predicted using a two-product SOA formation model, as done in many current climate models. Further investigation, including analysis on detailed mechanisms, are required to explain the discrepancy.

  6. An antibacterial and absorbable silk-based fixation material with impressive mechanical properties and biocompatibility

    PubMed Central

    Shi, Chenglong; Pu, Xiaobing; Zheng, Guan; Feng, Xinglong; Yang, Xuan; Zhang, Baoliang; Zhang, Yu; Yin, Qingshui; Xia, Hong

    2016-01-01

    Implant-associated infections and non-absorbing materials are two important reasons for a second surgical procedure to remove internal fixation devices after an orthopedic internal fixation surgery. The objective of this study was to produce an antibacterial and absorbable fixation screw by adding gentamicin to silk-based materials. The antibacterial activity was assessed against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) in vitro by plate cultivation and scanning electron microscopy (SEM). We also investigated the properties, such as the mechanical features, swelling properties, biocompatibility and degradation, of gentamicin-loaded silk-based screws (GSS) in vitro. The GSS showed significant bactericidal effects against S. aureus and E. coli. The antibacterial activity remained high even after 4 weeks of immersion in protease solution. In addition, the GSS maintained the remarkable mechanical properties and excellent biocompatibility of pure silk-based screws (PSS). Interestingly, after gentamicin incorporation, the degradation rate and water-absorbing capacity increased and decreased, respectively. These GSS provide both impressive material properties and antibacterial activity and have great potential for use in orthopedic implants to reduce the incidence of second surgeries. PMID:27869175

  7. Decontamination of skin exposed to nanocarriers using an absorbent textile material and PEG-12 dimethicone

    NASA Astrophysics Data System (ADS)

    Lademann, J.; Richter, H.; Baier, G.; Landfester, K.; Frazier, L.; Gefeller, H.; Wunderlich, U.; Gross, I.; Rühl, E.; Knorr, F.

    2014-11-01

    The removal of noxious particulate contaminants such as pollutants derived from particle-to-gas conversions from exposed skin is essential to avoid the permeation of potentially harmful substances into deeper skin layers via the stratum corneum or the skin appendages and their dispersion throughout the circulatory system. This study is aimed at evaluating the efficacy of using the silicone glycol polymer PEG-12 dimethicone and an absorbent textile material to remove fluorescing hydroxyethyl starch nanocapsules implemented as model contaminants from exposed porcine ear skin. Using laser scanning microscopy, it could be shown that while the application and subsequent removal of the absorbent textile material alone did not result in sufficient decontamination, the combined application with PEG-12 dimethicone almost completely eliminated the nanocapsules from the surface of the skin. By acting as a wetting agent, PEG-12 dimethicone enabled the transfer of the nanocapsules into a liquid phase which was taken up by the absorbent textile material. Only traces of fluorescence remained detectable in several skin furrows and follicular orifices, suggesting that the repeated implementation of the procedure may be necessary to achieve total skin surface decontamination.

  8. An antibacterial and absorbable silk-based fixation material with impressive mechanical properties and biocompatibility

    NASA Astrophysics Data System (ADS)

    Shi, Chenglong; Pu, Xiaobing; Zheng, Guan; Feng, Xinglong; Yang, Xuan; Zhang, Baoliang; Zhang, Yu; Yin, Qingshui; Xia, Hong

    2016-11-01

    Implant-associated infections and non-absorbing materials are two important reasons for a second surgical procedure to remove internal fixation devices after an orthopedic internal fixation surgery. The objective of this study was to produce an antibacterial and absorbable fixation screw by adding gentamicin to silk-based materials. The antibacterial activity was assessed against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) in vitro by plate cultivation and scanning electron microscopy (SEM). We also investigated the properties, such as the mechanical features, swelling properties, biocompatibility and degradation, of gentamicin-loaded silk-based screws (GSS) in vitro. The GSS showed significant bactericidal effects against S. aureus and E. coli. The antibacterial activity remained high even after 4 weeks of immersion in protease solution. In addition, the GSS maintained the remarkable mechanical properties and excellent biocompatibility of pure silk-based screws (PSS). Interestingly, after gentamicin incorporation, the degradation rate and water-absorbing capacity increased and decreased, respectively. These GSS provide both impressive material properties and antibacterial activity and have great potential for use in orthopedic implants to reduce the incidence of second surgeries.

  9. Optical waveguide materials, structures, and dispersion modulation

    NASA Astrophysics Data System (ADS)

    Zhang, Hao; Liu, Jiaming; Lin, Jian; Li, Wenxiu; Xue, Xia; Huang, Anping; Xiao, Zhisong

    2016-11-01

    Optical waveguide is used in most integrated optic devices to confine and guide light in higher refractive index channels. The structures and materials of slot waveguides are reviewed in this paper. Coupled resonator optical waveguides (CROWs) can be used for a rotation sensor with compact size, low power consumption and low cost. The loss determines the ultimate sensitivity of CROW gyros. Resonator-based optical gyroscope's sensitivity for measuring rotation is enhanced via using the anomalous dispersion characteristic of superluminal light propagation, which can be also generated by using passive optical resonators.

  10. Interior radiances in optically deep absorbing media. 3: Scattering from Haze L

    NASA Technical Reports Server (NTRS)

    Kattawar, G. W.; Plass, G. N.

    1974-01-01

    The interior radiances are calculated within an optically deep absorbing medium scattering according to the Haze L phase function. The dependence on the solar zenith angle, the single scattering albedo, and the optical depth within the medium is calculated by the matrix operator method. The development of the asymptotic angular distribution of the radiance in the diffusion region is illustrated through a number of examples; it depends only on the single scattering albedo and on the phase function for single scattering. The exact values of the radiance in the diffusion region are compared with values calculated from the approximate equations proposed by Van de Hulst. The variation of the radiance near the lower boundary of an optically thick medium is illustrated with examples. The attenuation length is calculated for various single scattering albedos and compared with the corresponding values for Rayleigh scattering. The ratio of the upward to the downward flux is found to be remarkably constant within the medium. The heating rate is calculated and found to have a maximum value at an optical depth of two within a Haze L layer when the sun is at the zenith.

  11. Mesoscale Engineering of Nanocomposite Nonlinear Optical Materials

    SciTech Connect

    Afonso, C.N.; Feldman, L.C.; Gonella, F.; Haglund, R.F.; Luepke, G.; Magruder, R.H.; Mazzoldi, P.; Osborne, D.H.; Solis, J.; Zuhr, R.A.

    1999-11-01

    Complex nonlinear optical materials comprising elemental, compound or alloy quantum dots embedded in appropriate dielectric or semiconducting hosts may be suitable for deployment in photonic devices. Ion implantation, ion exchange followed by ion implantation, and pulsed laser deposition have ail been used to synthesize these materials. However, the correlation between the parameters of energetic-beam synthesis and the nonlinear optical properties is still very rudimentary when one starts to ask what is happening at nanoscale dimensions. Systems integration of complex nonlinear optical materials requires that the mesoscale materials science be well understood within the context of device structures. We discuss the effects of beam energy and energy density on quantum-dot size and spatial distribution, thermal conductivity, quantum-dot composition, crystallinity and defects - and, in turn, on the third-order optical susceptibility of the composite material. Examples from recent work in our laboratories are used to illustrate these effects.

  12. Hybrid sol-gel optical materials

    DOEpatents

    Zeigler, J.M.

    1993-04-20

    Hybrid sol-gel materials comprise silicate sols cross-linked with linear polysilane, polygermane, or poly(silane-germane). The sol-gel materials are useful as optical identifiers in tagging and verification applications and, in a different aspect, as stable, visible light transparent non-linear optical materials. Methyl or phenyl silicones, polyaryl sulfides, polyaryl ethers, and rubbery polysilanes may be used in addition to the linear polysilane. The linear polymers cross-link with the sol to form a matrix having high optical transparency, resistance to thermooxidative aging, adherence to a variety of substrates, brittleness, and a resistance to cracking during thermal cycling.

  13. Hybrid sol-gel optical materials

    DOEpatents

    Zeigler, John M.

    1993-01-01

    Hybrid sol-gel materials comprise silicate sols cross-linked with linear polysilane, polygermane, or poly(silane-germane). The sol-gel materials are useful as optical identifiers in tagging and verification applications and, in a different aspect, as stable, visible light transparent non-linear optical materials. Methyl or phenyl silicones, polyaryl sulfides, polyaryl ethers, and rubbery polysilanes may be used in addition to the linear polysilane. The linear polymers cross-link with the sol to form a matrix having high optical transparency, resistance to thermooxidative aging, adherence to a variety of substrates, brittleness, and a resistance to cracking during thermal cycling.

  14. Hybrid sol-gel optical materials

    DOEpatents

    Zeigler, John M.

    1992-01-01

    Hybrid sol-gel materials comprise silicate sols cross-linked with linear polysilane, polygermane, or poly(silane-germane). The sol-gel materials are useful as optical identifiers in tagging and verification applications and, in a different aspect, as stable, visible light transparent non-linear optical materials. Methyl or phenyl silicones, polyaryl sulfides, polyaryl ethers, and rubbery polysilanes may be used in addition to the linear polysilane. The linear polymers cross-link with the sol to form a matrix having high optical transparency, resistance to thermooxidative aging, adherence to a variety of substrates, brittleness, and a resistance to cracking during thermal cycling.

  15. Stable phantom materials for ultrasound and optical imaging

    NASA Astrophysics Data System (ADS)

    Cabrelli, Luciana C.; Pelissari, Pedro I. B. G. B.; Deana, Alessandro M.; Carneiro, Antonio A. O.; Pavan, Theo Z.

    2017-01-01

    Phantoms mimicking the specific properties of biological tissues are essential to fully characterize medical devices. Water-based materials are commonly used to manufacture phantoms for ultrasound and optical imaging techniques. However, these materials have disadvantages, such as easy degradation and low temporal stability. In this study, we propose an oil-based new tissue-mimicking material for ultrasound and optical imaging, with the advantage of presenting low temporal degradation. A styrene-ethylene/butylene-styrene (SEBS) copolymer in mineral oil samples was made varying the SEBS concentration between 5%-15%, and low-density polyethylene (LDPE) between 0%-9%. Acoustic properties, such as the speed of sound and the attenuation coefficient, were obtained using frequencies ranging from 1-10 MHz, and were consistent with that of soft tissues. These properties were controlled varying SEBS and LDPE concentration. To characterize the optical properties of the samples, the diffuse reflectance and transmittance were measured. Scattering and absorption coefficients ranging from 400 nm-1200 nm were calculated for each compound. SEBS gels are a translucent material presenting low optical absorption and scattering coefficients in the visible region of the spectrum, but the presence of LDPE increased the turbidity. Adding LDPE increased the absorption and scattering of the phantom materials. Ultrasound and photoacoustic images of a heterogeneous phantom made of LDPE/SEBS containing a spherical inclusion were obtained. Annatto dye was added to the inclusion to enhance the optical absorbance. The results suggest that copolymer gels are promising for ultrasound and optical imaging, making them also potentially useful for photoacoustic imaging.

  16. Molecules and metals in the distant universe: Sub-mm and optical spectroscopy of quasar absorbers

    NASA Astrophysics Data System (ADS)

    Morrison, Sean Stephen

    In order to gain a complete understanding of galaxy formation and evolution, knowledge of the atomic and molecular gas in the interstellar medium (ISM) is required. Absorption-line spectroscopy of quasars offer a powerful and luminosity independent probe of gas to high redshifts. The sub-Damped Lyman-alpha systems (sub-DLAs; 19.0 < log NHI < 20.3), and Damped Lyman-alpha systems (DLAs; 20.3 < log NHI), are the highest neutral hydrogen column density quasar absorbers contain most of the neutral gas available for star formation in the high-redshift Universe. This thesis presents photometric measurements of 10 quasars absorbers with redshifts 0.652 < zabs < 3.104 taken with the Spectral and Photometric Imaging Receiver (SPIRE) on Herschel. Of these 10 objects, 3 showed fluxes > 1 Jy. In addition spectra for 5 other quasars with DLAs (0.524 < zabs < 1.173) were taken with SPIRE and Heterodyne Instrument for the far-infrared (HIFI) on Herschel. These observations, in the far-IR and sub-mm bands, were optimized for detection of molecular lines of CO, 13CO, C 18O, H2O, HCO, and the forbidden transitions of [C II] and [N II]. Two targets, the DLA towards PKS0420-014 at z = 0.633 and the DLA towards AO0235+164 at z = 0.524, had a tentative detection of C18O, and another, the DLA towards TXS0827+243 at z = 0.52476, had a tentative detection of HCO. There were a number of other 3 sigma limits, with at least one limit for each of the 5 systems. In addition to the DLAs, 2 super-DLAs (with z = 2.5036 and z = 2.045) were observed using the echellette mode on Keck Echellette Spectrograph and Imager (ESI). These observations, in the optical and ultraviolet wavelengths, were optimized to detect metal lines. Both absorbers show remarkably similar metallicities of ~ -1.3 to ~ -1.4 dex and comparable, definitive depletion levels, as judged from [Fe/Zn] and [Ni/Zn]. One of the absorbers shows supersolar [S/Zn] and [Si/Zn]. Using potential detections of weak Ly-alpha emission at the

  17. Optical properties of transparent cobalt-containing magnesium aluminosilicate glass-ceramics doped with gallium oxide for saturable absorbers

    NASA Astrophysics Data System (ADS)

    Loiko, P. A.; Skoptsov, N. A.; Dymshits, O. S.; Malyarevich, A. M.; Yumashev, K. V.; Zhilin, A. A.; Alekseeva, I. P.

    2016-10-01

    Transparent glass-ceramic materials based on glasses of the MgO-Al2O3-SiO2-TiO2 system doped with CoO and Ga2O3 are synthesized. The secondary heat treatment of the initial glasses at temperatures of 800-950°C leads to precipitation of nanosized (6-7 nm) crystals of magnesium aluminogallium spinel doped with cobalt ions and magnesium aluminotitanate solid solutions. The optical absorption spectra of the initial glass and glass-ceramic materials are studied. It is shown that the absorption band caused by the 4 A 2(4F)→ 4 T 1(4 F) transitions of tetrahedrally coordinated Co2+ ions in glass-ceramics with nanosized Co:Mg(Al,Ga)2O4 crystals is shifted to longer wavelengths (up to 1.67 µm) compared to the position of this band in materials with Co:MgAl2O4 crystals. The synthesized glass-ceramics are characterized by a relatively low saturation fluence FS 0.5 ± 0.1 J/cm2 at a wavelength of 1.54 µm, as well as by a high radiation resistance to nanosecond laser pulses, which is no lower than 15 ± 2 J/cm2. This explains their attractiveness as materials for saturable absorbers for erbium lasers emitting in the spectral range 1.5-1.7 µm.

  18. Super water-absorbing new material from chitosan, EDTA and urea.

    PubMed

    Narayanan, Abathodharanan; Dhamodharan, Raghavachari

    2015-12-10

    A new, super water-absorbing, material is synthesized by the reaction between chitosan, EDTA and urea and named as CHEDUR. CHEDUR is probably formed through the crosslinking of chitosan molecules (CH) with the EDTA-urea (EDUR) adduct that is formed during the reaction. CHEDUR as well as the other products formed in control reactions are characterized extensively. CHEDUR exhibits a very high water uptake capacity when compared with chitosan, chitosan-EDTA adduct, as well as a commercial diaper material. A systematic study was done to find the optimum composition as well as reaction conditions for maximum water absorbing capacity. CHEDUR can play a vital role in applications that demand the rapid absorption and slow release of water such as agriculture, as a three in one new material for the slow release of urea, water and other metal ions that can be attached through the EDTA component. The other potential advantage of CHEDUR is that it can be expected to degrade in soil based on its chitosan backbone. The new material with rapid and high water uptake could also find potential applications as biodegradable active ingredient of the diaper material.

  19. Development of microwave absorbing materials prepared from a polymer binder including Japanese lacquer and epoxy resin

    NASA Astrophysics Data System (ADS)

    Iwamaru, T.; Katsumata, H.; Uekusa, S.; Ooyagi, H.; Ishimura, T.; Miyakoshi, T.

    Microwave absorption composites were synthesized from a poly urushiol epoxy resin (PUE) mixed with one of microwave absorbing materials; Ni-Zn ferrite, Soot, Black lead, and carbon nano tube (CNT) to investigate their microwave absorption properties. PUE binders were specially made from Japanese lacquer and epoxy resin, where Japanese lacquer has been traditionally used for bond and paint because it has excellent beauty. Japanese lacquer solidifies with oxygen contained in air's moisture, which has difficulty in making composite, but we improved Japanese lacquer's solidification properties by use of epoxy resin. We made 10 mm thickness composite samples and cut them into toroidal shape to measure permittivity, permeability, and reflection loss in frequencies ranging from 50 Hz to 20 GHz. Electric magnetic absorber's composites synthesized from a PUE binders mixed either with Soot or CNT showed significantly higher wave absorption over -27 dB than the others at frequencies around 18 GHz, although Japanese lacquer itself doesn't affect absorption. This means Japanese lacquer can be used as binder materials for microwave absorbers.

  20. Evaluation of polypropylene and poly (butylmethacrylate-co-hydroxyethylmethacrylate) nonwoven material as oil absorbent.

    PubMed

    Zhao, Jian; Xiao, Changfa; Xu, Naiku

    2013-06-01

    Polypropylene (PP) and poly(butylmethacrylate-co-hydroxyethylmethacrylate) (PBMA-co-HEMA) nonwoven materials as oil absorbents have been fabricated for the first time via melt blown method. As-prepared nonwovens were investigated in terms of mass per unit area, density, air permeability, contact angle, and morphology observations for fiber diameter distribution and single fiber surface by a field emission scanning electron microscope. The nonwovens are demonstrated as fast and efficient absorbents for various kinds of oils with oil absorbency up to seven to ten times their own weight. The nonwovens show excellent water repulsion but superoleophilic properties. The measured contact angles for water and toluene are more than 127° and ca. 0°, respectively. The addition of PBMA-co-HEMA makes the nonwoven surface more hydrophobic while conserving superoleophilicity. Compared with PP nonwoven, broad diameter distribution of the blend nonwoven is attributed to poor melt fluidity of PBMA-co-HEMA. In terms of single fiber, coarse surface and the presence of point-like convexities lead to the fibers being more readily wetted by oil. More interesting, oil-water separation and oil recovery can be easily carried out by filter and absorption-desorption process, the recovered materials contained hardly any oil droplet and could be reused for next cycles.

  1. Optical limiting materials based on fullerene derivatives

    SciTech Connect

    Prato, Maurizio; Maggini, Michele; Scorrano, Gianfranco; Brusatin, Giovanna; Guglielmi, Massimo; Meneghetti, Moreno; Signorini, Raffaella; Bozio, Renato; Guldi, Dirk M.

    1999-09-30

    A functionalized fulleropyrrolidine has been synthesized and investigated for optical limiting applications. Solid materials have been prepared for optical limiting devices by incorporation in sol-gel glasses. Their nonlinear transmission properties have been measured and found comparable with those of solution samples. We show that clustering of the fullerene spheres, which might affect the optical limiting properties, is not relevant. Multilayer structures following a bottleneck design are prepared and their NL transmission properties are characterized. (c) 1999 American Institute of Physics.

  2. Carbon nanotube scaffolds with controlled porosity as electromagnetic absorbing materials in the gigahertz range.

    PubMed

    González, M; Crespo, M; Baselga, J; Pozuelo, J

    2016-05-19

    Control of the microscopic structure of CNT nanocomposites allows modulation of the electromagnetic shielding in the gigahertz range. The porosity of CNT scaffolds has been controlled by two freezing protocols and a subsequent lyophilization step: fast freezing in liquid nitrogen and slow freezing at -20 °C. Mercury porosimetry shows that slowly frozen specimens present a more open pore size (100-150 μm) with a narrow distribution whereas specimens frozen rapidly show a smaller pore size and a heterogeneous distribution. 3D-scaffolds containing 3, 4, 6 and 7% CNT were infiltrated with epoxy and specimens with 2, 5 and 8 mm thicknesses were characterized in the GHz range. Samples with the highest pore size and porosity presented the lowest reflected power (about 30%) and the highest absorbed power (about 70%), which allows considering them as electromagnetic radiation absorbing materials.

  3. Aging behavior of polymeric solar absorber materials: Aging on the component level

    SciTech Connect

    Kahlen, S.; Wallner, G.M.; Lang, R.W.; Meir, M.; Rekstad, J.

    2010-03-15

    Within this study, the aging behavior of a PPE + PS absorber material was investigated on the absorber component level. To indicate aging, characteristic mechanical values were determined by indentation tests of specimens taken from components and exposed to laboratory aging (140 C in air, 80 C in water) and service near outdoor aging conditions (stagnation in northern climate). In addition to the mechanical tests, the unaged and aged specimens were also characterized thermo-analytically via differential scanning calorimetry (DSC). The results indicate that reductions in both characteristic mechanical values of the indentation tests, i.e., load of the first transition and ultimate indentation, reflect at least some physical aging although chemical aging may also be of importance based on previous analytical investigations of laboratory aged polymer films. While laboratory aging in air at 140 C and service exposure at a test facility in Oslo (N) under stagnation conditions led to a significant reduction in the mechanical indentation resistance, no influence of laboratory aging in water at 80 C on the mechanical behavior of the absorber sheet was found. Depending on the ultimate failure criterion applied (reduction of characteristic mechanical values to 80% and 50%, respectively), the technical service life found for hot air laboratory and stagnation service conditions was found to be less than 51 and 159 h, respectively. As these durations are significantly below the estimated stagnation conditions accumulated in the desired operation lifetime for such a collector, the PPE + PS type investigated does not seem to be a proper material candidate for solar thermal absorbers. Finally, based on the results obtained, a relation between laboratory aging time in air at 140 C and cumulated irradiation energy during exposure on the test facility in Oslo was established. (author)

  4. Hybrid materials for optics and photonics.

    PubMed

    Lebeau, Benedicte; Innocenzi, Plinio

    2011-02-01

    The interest in organic-inorganic hybrids as materials for optics and photonics started more than 25 years ago and since then has known a continuous and strong growth. The high versatility of sol-gel processing offers a wide range of possibilities to design tailor-made materials in terms of structure, texture, functionality, properties and shape modelling. From the first hybrid material with optical functional properties that has been obtained by incorporation of an organic dye in a silica matrix, the research in the field has quickly evolved towards more sophisticated systems, such as multifunctional and/or multicomponent materials, nanoscale and self-assembled hybrids and devices for integrated optics. In the present critical review, we have focused our attention on three main research areas: passive and active optical hybrid sol-gel materials, and integrated optics. This is far from exhaustive but enough to give an overview of the huge potential of these materials in photonics and optics (254 references).

  5. Method and apparatus for determining the content and distribution of a thermal neutron absorbing material in an object

    DOEpatents

    Crane, Thomas W.

    1986-01-01

    The disclosure is directed to an apparatus and method for determining the content and distribution of a thermal neutron absorbing material within an object. Neutrons having an energy higher than thermal neutrons are generated and thermalized. The thermal neutrons are detected and counted. The object is placed between the neutron generator and the neutron detector. The reduction in the neutron flux corresponds to the amount of thermal neutron absorbing material in the object. The object is advanced past the neutron generator and neutron detector to obtain neutron flux data for each segment of the object. The object may comprise a space reactor heat pipe and the thermal neutron absorbing material may comprise lithium.

  6. Method and apparatus for determining the content and distribution of a thermal neutron absorbing material in an object

    DOEpatents

    Crane, T.W.

    1983-12-21

    The disclosure is directed to an apparatus and method for determining the content and distribution of a thermal neutron absorbing material within an object. Neutrons having an energy higher than thermal neutrons are generated and thermalized. The thermal neutrons are detected and counted. The object is placed between the neutron generator and the neutron detector. The reduction in the neutron flux corresponds to the amount of thermal neutron absorbing material in the object. The object is advanced past the neutron generator and neutron detector to obtain neutron flux data for each segment of the object. The object may comprise a space reactor heat pipe and the thermal neutron absorbing material may comprise lithium.

  7. Synthesis and properties of near infrared-absorbing magnetic-optical nanopins

    NASA Astrophysics Data System (ADS)

    Bhana, Saheel; Rai, Binod K.; Mishra, Sanjay R.; Wang, Yongmei; Huang, Xiaohua

    2012-07-01

    Novel near infrared-absorbing iron oxide-gold core-shell nanoparticles in pin shapes were synthesized. The nanopins are superparamagnetic, with 35-fold better surface enhanced Raman scattering activities than the conventional core-shell nanospheres and 50-fold greater photothermal properties than solid gold nanorods. The nanoparticles will have important impact on medical imaging, molecular diagnostics and disease treatment.Novel near infrared-absorbing iron oxide-gold core-shell nanoparticles in pin shapes were synthesized. The nanopins are superparamagnetic, with 35-fold better surface enhanced Raman scattering activities than the conventional core-shell nanospheres and 50-fold greater photothermal properties than solid gold nanorods. The nanoparticles will have important impact on medical imaging, molecular diagnostics and disease treatment. Electronic supplementary information (ESI) available: Experimental details, absorption spectrum of IO NPs, TEM images of IO-Ag seeds, TEM image and optical absorption spectra of IO-Au nanospheres. See DOI: 10.1039/c2nr31291c

  8. Partial Pressures of In-Se from Optical Absorbance of the Vapor

    NASA Technical Reports Server (NTRS)

    Brebrick, R. F.; Su, Ching-Hua; Curreri, Peter A. (Technical Monitor)

    2001-01-01

    The optical absorbance of the vapor phase over various In-Se compositions between 33.3 and 61 atomic percent and 673 and 1418K has been measured and used to obtain the partial pressures of Se2(g) and In2Se(g). The results are in agreement with silica Bourdon gage measurements for compositions between 50 and 61 atomic percent but significantly higher than those from Knudsen cell and simultaneous Torsion-Knudsen cell measurements. The sequiselenide is found to sublime incongruently. Congruent vaporization occurs for the liquid above 1000 K between 50.08 and 56 at. percent Se. The Gibbs energy of formation of the liquid from its pure liquid elements between 1000 and 1300K is essentially independent of temperature and falls between -36 and -38 kJ per gram atomic weight for 50 and 56 percent Se at 1200 and 1300K.

  9. Partial Pressures for Several In-Se Compositions from Optical Absorbance of the Vapor

    NASA Technical Reports Server (NTRS)

    Brebrick, R. F.; Su, Ching-Hua

    2001-01-01

    The optical absorbance of the vapor phase over various In-Se compositions between 33.3-60.99 at.% Se and 673-1418 K was measured and used to obtain the partial pressures of Se2(g) and In2Se(g). The results are in agreement with silica Bourdon gauge measurements for compositions between 50-61 at.%, but significantly higher than those from Knudsen cell and simultaneous Knudsen-torsion cell measurements. It is found that 60.99 at.% Se lies outside the sesquiselenide homogeneity range and 59.98 at.% Se lies inside and is the congruently melting composition. The Gibbs energy of formation of the liquid from its pure liquid elements between 1000-1300 K is essentially independent of temperature and falls between -36 to -38 kJ per g atomic weight for 50 and 56% Se at 1200 and 1300 K.

  10. Nonlinear Optics and Organic Materials

    DTIC Science & Technology

    1989-10-01

    unmatched brilliance both probes a nd inelh~" ...) / these novel effects . A detailed understanding of the nature ,S .i of light, and how it interacts with...matter, is essential to evince these effects . Although everyday optical tools- windowpanes and eyeglasses-may remain unaffected, " such delicate...use the same pair of binoculars to focus on a faint star at night and a bird in daylight (1, 2). Intensity-dependent nonlinear effects However, when

  11. Field-Sensitive Materials for Optical Applications

    NASA Technical Reports Server (NTRS)

    Choi, Sang H.; Little, Mark

    2002-01-01

    The purpose of investigation is to develop the fundamental materials and fabrication technology for field-controlled spectrally active optics that are essential for industry, NASA, and DOD (Department of Defense) applications such as: membrane optics, filters for LIDARs (Light Detection and Ranging), windows for sensors and probes, telescopes, spectroscopes, cameras, light valves, light switches, flat-panel displays, etc. The proposed idea is based on the quantum-dots (QD) array or thin-film of field-sensitive Stark and Zeeman materials and the bound excitonic state of organic crystals that will offer optical adaptability and reconfigurability. Major tasks are the development of concept demonstration article and test data of field-controlled spectrally smart active optics (FCSAO) for optical multi-functional capabilities on a selected spectral range.

  12. Development of New Electro-Optic and Acousto-Optic Materials.

    DTIC Science & Technology

    1983-11-01

    Improved materials are required for active optical devices, including electro - optic and acousto-optic modulators, switches and tunable filters, as...many microwave applications. In addition, electro - optic and acousto-optic devices are materials limited because the materials currently available are...these materials for applications involving the electro - optic effect, degenerate four-wave mixing and surface acoustic wave technology.

  13. The NuSTAR View of Reflecting and Absorbing Circumnuclear Material in AGN

    NASA Astrophysics Data System (ADS)

    Rivers, Elizabeth

    2016-04-01

    The physical conditions and precise geometry of the accreting circumnuclear material in the vicinity of supermassive black holes remain open and critical questions. Between July 2012 and February 2013, NuSTAR and XMM-Newton performed four long-look joint observations of the type 1.8 Seyfert, NGC 1365. We have analyzed the variable absorption seen in these observations in order to characterize the geometry of the absorbing material. Two of the observations caught NGC 1365 in an unusually low absorption state, revealing complexity in the multi-layer absorbers which had previously been hidden, including a the Compton-thick torus, BLR clouds, and a patchy absorber with a variable column around 1022 cm-2 and a line of sight covering fraction of 0.3-0.9 which responds directly to the intrinsic source flux, possibly due to a wind geometry. We have also analyzed two NuSTAR observations of NGC 7582, a well-studied X-ray bright Seyfert 2 with moderately heavy highly variable absorption and strong reflection spectral features. Changes in the spectral shape and high reflection fractions have led to competing explanations: 1) the central X-ray source partially “shut off”, decreasing in intrinsic luminosity, with a delayed decrease in reflection features due to the light-crossing time of the Compton-thick material or 2) the source became more heavily obscured, with only a portion of the power law continuum leaking through. The high quality of the NuSTAR spectra above 10 keV give us the best look at the reflection hump to date and allow us to test these two scenarios.

  14. Does the composition of urine change when collected from disposable diapers and other absorbent materials?

    PubMed

    Ye, Xiaoyun; Zhou, Xiaoliu; Bishop, Amber M; Needham, Larry L; Calafat, Antonia M

    2010-11-01

    The free and conjugated urinary species of non-persistent environmental chemicals or their breakdown products are valid human exposure biomarkers. For convenience, disposable diapers and other absorbent materials are widely used to collect urine specimens from infants and young toddlers. However, the extent to which the different urinary species of the target analytes and other components are recovered after the urine is extracted from these absorbent materials is unknown. In this proof-of-concept study, we investigated the extraction recovery from disposable diapers, cotton pads, and gauzes of the free versus glucuronidated urinary species of three example chemicals: bisphenol A, triclosan, and 4-methylumbelliferone. Although the glucuronides were almost fully recovered, the free species were not. Our results suggest that, in addition to other sampling considerations, the binding affinity and extraction recovery of the target biomarkers to the material used to collect the urine should be considered. Alternative collection approaches that do not require such an extraction (e.g., urine bags routinely used in hospitals) may be worth exploring. Despite its shortcomings, having urinary concentrations for biomonitoring considerably strengthens the exposure assessment, particularly for infants and young toddlers, and the benefits of including biomonitoring data outweigh their potential limitations.

  15. Photosensitive Materials for Integrated Optic Applications

    NASA Astrophysics Data System (ADS)

    Marques, P. V. S.; Moreira, P. J.; Alexandre, D.; Melo, M.; Schmidt, T. E. A.; Muenzner, R.; Leite, A. M. P.; Aitchison, J. S.

    This article presents results of device fabrication using UV processing of materials and integrated optic components produced by flame hydrolysis deposition and hybrid sol-gel technology. Photosensitive materials were employed in the fabrication of channel waveguides and channel photo-imprinted waveguides incorporating Bragg gratings through single and double-step exposure.

  16. Nonlinear optical transmission of cyanobacteria-derived optical materials

    NASA Astrophysics Data System (ADS)

    Zhao, Edward H.; Watanabe, Fumiya; Zhao, Wei

    2015-08-01

    Cyanobacteria-derived optical materials for optical limiting applications have been studied in this work. Six samples have been prepared from cyanobacteria including cyanobacteria suspension in water, extracts in water, methanol, and N,N-dimethylformamide, and pyrolyzed cyanobacteria (PCYB) dispersed in dsDNA (sodium salt from salmon testes) solution and sodium dodecyl sulfate solution, respectively. The extracts contain phycocyanin, chlorophyll a, and carotenoids as measured by optical absorption spectroscopy, while the PCYB is a nanostructural composite composed of multi-walled carbon nanotubes, carbon nanoringes, and multilayer graphenes, as revealed by transmission electron microscopy. The optical limiting responses of the samples have been measured at 532 and 756 nm. The PCYB in dsDNA solution has the best limiting performance out of all the cyanobacteria-derived samples. It outperforms carbon black suspension standard at 532 nm and is a broadband limiter, which makes it attractive for optical limiting applications.

  17. Terahertz material characterization for nonreciprocal integrated optics

    NASA Astrophysics Data System (ADS)

    Mičica, Martin; Postava, Kamil; Vanwolleghem, Mathias; Horák, Tomáś; Lampin, Jean François; Pištora, Jaromír.

    2015-05-01

    Interest in nonreciprocal terahertz (THz) integrated optics makes necessity to look for new materials active in this region and precisely characterize their optical properties. In this paper we present important aspects of the methods for determination of optical functions in far infrared (FIR) and THz spectral range. The techniques are applied to polyethylene cyclic olefin copolymer (Topas) and hexaferrites (BaFe12O19, SrFe12O19). Topas is promising material in integrated optics for THz radiation, thanks to its low absorption in this region. On the other hand, hexaferrites with its magneto-optic properties can be used for nonreciprocal integrated optic parts and radiation control. Samples were studied by THz time domain spectroscopy (THz-TDS) in spectral range 2 - 100 cm-1 by transmission and reflection. Advantage of presented THz time domain spectroscopy is measurement of the electric field wavefunction, which allows to obtain both the amplitude and phase spectra. In results we provide measured data, processing, and final computed optical properties of Topas and hexaferrites which reveal interesting optical behaviour in THz spectral range.

  18. Modeling of optically controlled reflective bistability in a vertical cavity semiconductor saturable absorber

    NASA Astrophysics Data System (ADS)

    Mishra, L.

    2015-05-01

    Bistability switching between two optical signals has been studied theoretically utilizing the concept of cross absorption modulation in a vertical cavity semiconductor saturable absorber (VCSSA). The probe beam is fixed at a wavelength other than the low power cavity resonance wavelength, which exhibits bistable characteristic by controlling the power of a pump beam (λpump≠λprobe). The cavity nonlinear effects that arises simultaneously from the excitonic absorption bleaching, and the carrier induced nonlinear index change has been considered in the model. The high power absorption in the active region introduces thermal effects within the nonlinear cavity due to which the effective cavity length changes. This leads to a red-shift of the cavity resonance wavelength, which results a change in phase of the optical fields within the cavity. In the simulation, the phase-change due to this resonance shifting is considered to be constant over time, and it assumes the value corresponding to the maximum input power. Further, an initial phase detuning of the probe beam has been considered to investigate its effect on switching. It is observed from the simulated results that, the output of the probe beam exhibits either clockwise or counter-clockwise bistability, depending on its initial phase detuning.

  19. A Phosphorus Phthalocyanine Formulation with Intense Absorbance at 1000 nm for Deep Optical Imaging

    PubMed Central

    Zhou, Yang; Wang, Depeng; Zhang, Yumiao; Chitgupi, Upendra; Geng, Jumin; Wang, Yuehang; Zhang, Yuzhen; Cook, Timothy R.; Xia, Jun; Lovell, Jonathan F.

    2016-01-01

    Although photoacoustic computed tomography (PACT) operates with high spatial resolution in biological tissues deeper than other optical modalities, light scattering is a limiting factor. The use of longer near infrared wavelengths reduces scattering. Recently, the rational design of a stable phosphorus phthalocyanine (P-Pc) with a long wavelength absorption band beyond 1000 nm has been reported. Here, we show that when dissolved in liquid surfactants, P-Pc can give rise to formulations with absorbance of greater than 1000 (calculated for a 1 cm path length) at wavelengths beyond 1000 nm. Using the broadly accessible Nd:YAG pulse laser emission output of 1064 nm, P-Pc could be imaged through 11.6 cm of chicken breast with PACT. P-Pc accumulated passively in tumors following intravenous injection in mice as observed by PACT. Following oral administration, P-Pc passed through the intestine harmlessly, and PACT could be used to non-invasively observe intestine function. When the contrast agent placed under the arm of a healthy adult human, a PACT transducer on the top of the arm could readily detect P-Pc through the entire 5 cm limb. Thus, the approach of using contrast media with extreme absorption at 1064 nm readily enables high quality optical imaging in vitro and in vivo in humans at exceptional depths. PMID:27022416

  20. Electro-optic modulator material

    DOEpatents

    Adams, John J.; Ebbers, Chris A.

    2005-02-22

    An electro-optic device for use with a laser beam. A crystal has a first face and a second face. Means are provided for applying a voltage across the crystal to obtain a net phase retardation on the polarization of the laser beam when the laser beam is passed through the crystal. In one embodiment the crystal is composed of a compound having the chemical formula ReAe40(BO3)3 where: RE consists of one or more of the following elements La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and two other elements Y and Sc; and where Ae is from the list of Ca, Sr, or Ba.

  1. Scientists Identify New Quaternary Materials for Solar Cell Absorbers (Fact Sheet), NREL Highlights, Science

    SciTech Connect

    Not Available

    2011-10-01

    Research provides insight for exploring use of earth-abundant quaternary semiconductors for large-scale solar cell applications. For large-scale solar electricity generation, it is critical to find new material that is Earth abundant and easily manufactured. Previous experimental studies suggest that Cu{sub 2}ZnSnS{sub 4} could be a strong candidate absorber materials for large-scale thin-film solar cells due to its optimal bandgap, high adsorption coefficient, and ease of synthesis. However, due to the complicated nature of the quaternary compound, it is unclear whether other quaternary compounds have physical properties suitable for solar cell application. Researchers at the National Renewable Energy Laboratory (NREL), Fudan University, and University College London have performed systematic searches of quaternary semiconductors using a sequential cation mutation method in which the material properties of the quaternary compounds can be derived and understood through the evolution from the binary, to ternary, and to quaternary compounds. The searches revealed that in addition to Cu{sub 2}ZnSnS{sub 4}, Cu{sub 2}ZnGeSe{sub 4} and Cu{sub 2}ZnSnSe{sub 4} are also suitable quaternary materials for solar cell absorbers. Through the extensive study of defect and alloy properties of these materials, the researchers propose that to maximize solar cell performance, growth of Cu{sub 2}ZnSnS{sub 4} under Cu-poor/Zn-rich conditions will be optimal and the formation of Cu{sub 2}ZnSn(S,Se){sub 4} alloy will be beneficial in improving solar cell performance.

  2. Optical Properties of Moderately-Absorbing Organic and Mixed Organic/Inorganic Particles at Very High Humidities

    SciTech Connect

    Bond, Tami C; Rood, Mark J; Brem, Benjamin T; Mena-Gonzalez, Francisco C; Chen, Yanju

    2012-04-16

    Relative humidity (RH) affects the water content of an aerosol, altering its ability to scatter and absorb light, which is important for aerosol effects on climate and visibility. This project involves in situ measurement and modeling of aerosol optical properties including absorption, scattering and extinction at three visible wavelengths (467, 530, 660 nm), for organic carbon (OC) generated by pyrolysis of biomass, ammonium sulfate and sodium chloride, and their mixtures at controlled RH conditions. Novel components of this project include investigation of: (1) Changes in all three of these optical properties at scanned RH conditions; (2) Optical properties at RH values up to 95%, which are usually extrapolated instead of measured; and (3) Examination of aerosols generated by the pyrolysis of wood, which is representative of primary atmospheric organic carbon, and its mixture with inorganic aerosol. Scattering and extinction values were used to determine light absorption by difference and single scattering albedo values. Extensive instrumentation development and benchmarking with independently measured and modeled values were used to obtain and evaluate these new results. The single scattering albedo value for a dry absorbing polystyrene microsphere benchmark agreed within 0.02 (absolute value) with independently published results at 530 nm. Light absorption by a nigrosin (sample light-absorbing) benchmark increased by a factor of 1.24 +/-0.06 at all wavelengths as RH increased from 38 to 95%. Closure modeling with Mie theory was able to reproduce this increase with the linear volume average (LVA) refractive index mixing rule for this water soluble compound. Absorption by biomass OC aerosol increased by a factor of 2.1 +/- 0.7 and 2.3 +/- 1.2 between 32 and 95% RH at 467 nm and 530 nm, but there was no detectable absorption at 660 nm. Additionally, the spectral dependence of absorption by OC that was observed with filter measurements was confirmed qualitatively

  3. Concentration measurements of complex mixtures of broadband absorbers by widely tunable optical parametric oscillator laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Ruxton, K.; Macleod, N. A.; Weidmann, D.; Malcolm, G. P. A.; Maker, G. T.

    2012-11-01

    The ability to obtain accurate vapour parameter information from a compound's absorption spectrum is an essential data processing application in order to quantify the presence of an absorber. Concentration measurements can be required for a variety of applications including environmental monitoring, pipeline leak detection, surface contamination and breath analysis. This work demonstrates sensitive concentration measurements of complex mixtures of volatile organic compounds (VOCs) using broadly tunable mid wave infrared (MWIR) laser spectroscopy. Due to the high absorption cross-sections, the MWIR spectral region is ideal to carry out sensitive concentration measurements of VOCs by tunable laser absorption spectroscopy (TLAS) methods. Absorption spectra of mixtures of VOCs were recorded using a MWIR optical parametric oscillator (OPO), with a tuning range covering 2.5 μm to 3.7 μm. The output of the MWIR OPO was coupled to a multi-pass astigmatic Herriott gas cell, maintained at atmospheric pressure that can provide up to 210 m of absorption path length, with the transmission output from the cell being monitored by a detector. The resulting spectra were processed by a concentration retrieval algorithm derived from the optimum estimation method, taking into account both multiple broadband absorbers and interfering molecules that exhibit narrow multi-line absorption features. In order to demonstrate the feasibility of the concentration measurements and assess the capability of the spectral processor, experiments were conducted on calibrated VOCs vapour mixtures flowing through the spectroscopic cell with concentrations ranging from parts per billion (ppb) to parts per million (ppm). This work represents as a first step in an effort to develop and apply a similar concentration fitting algorithm to hyperspectral images in order to provide concentration maps of the spatial distribution of multi-species vapours. The reported functionality of the novel fitting algorithm

  4. Absorbing aerosols at high relative humidity: linking hygroscopic growth to optical properties

    NASA Astrophysics Data System (ADS)

    Flores, J. Michel; Bar-Or, R. Z.; Bluvshtein, N.; Abo-Riziq, A.; Kostinski, A.; Borrmann, S.; Koren, I.; Koren, I.; Rudich, Y.

    2012-06-01

    One of the major uncertainties in the understanding of Earth's climate system is the interaction between solar radiation and aerosols in the atmosphere. Aerosols exposed to high humidity will change their chemical, physical, and optical properties due to their increased water content. To model hydrated aerosols, atmospheric chemistry and climate models often use the volume weighted mixing rule to predict the complex refractive index (RI) of aerosols when they interact with high relative humidity, and, in general, assume homogeneous mixing. This study explores the validity of these assumptions. A humidified cavity ring down aerosol spectrometer (CRD-AS) and a tandem hygroscopic DMA (differential mobility analyzer) are used to measure the extinction coefficient and hygroscopic growth factors of humidified aerosols, respectively. The measurements are performed at 80% and 90%RH at wavelengths of 532 nm and 355 nm using size-selected aerosols with different degrees of absorption; from purely scattering to highly absorbing particles. The ratio of the humidified to the dry extinction coefficients (fRHext(%RH, Dry)) is measured and compared to theoretical calculations based on Mie theory. Using the measured hygroscopic growth factors and assuming homogeneous mixing, the expected RIs using the volume weighted mixing rule are compared to the RIs derived from the extinction measurements. We found a weak linear dependence or no dependence of fRH(%RH, Dry) with size for hydrated absorbing aerosols in contrast to the non-monotonically decreasing behavior with size for purely scattering aerosols. No discernible difference could be made between the two wavelengths used. Less than 7% differences were found between the real parts of the complex refractive indices derived and those calculated using the volume weighted mixing rule, and the imaginary parts had up to a 20% difference. However, for substances with growth factor less than 1.15 the volume weighted mixing rule assumption

  5. ABSORBANCE, ABSORPTION COEFFICIENT, AND APPARENT QUANTUM YIELD: A COMMENT ON AMBIGUITY IN THE USE OF THESE OPTICAL CONCEPTS

    EPA Science Inventory

    Several important optical terms such as "absorbance" and "absorption coefficient" are frequently used ambiguously in the current peer-reviewed literature. Since they are important terms that are required to derive other quantities such as the "apparent quantum yield" of photoprod...

  6. Magnetism, optical absorbance, and 19F NMR spectra of nafion films with self-assembling paramagnetic networks

    SciTech Connect

    Levin, E. M.; Chen, Q.; Bud'ko, S. L.

    2012-01-15

    Magnetization, optical absorbance, and {sup 19}F NMR spectra of Nafion transparent films as received and doped with Mn{sup 2+}, Co{sup 2+}, Fe{sup 2+}, and Fe{sup 3+} ions with and without treatment in 1H-1,2,4-triazole (trz) have been studied. Doping of Nafion with Fe{sup 2+} and Co{sup 2+} and their bridging to nitrogen of triazole yields a hybrid self-assembling paramagnetic system that exhibits interesting magnetic and optical properties. These include spin crossover phenomena between high-spin (HS) and low-spin (LS) states in Nafion-Fe{sup 2+}-trz and Nafion-Co{sup 2+}-trz accompanied by thermochromic effects in the visible range induced by temperature. A large shift of the magnetization curve induced by a magnetic field in the vicinity of the HS {leftrightarrow} LS, {approx}220 K, observed for Nafion-Fe{sup 2+}-trz has a rate of {approx}6 K/kOe, which is about three orders of magnitude larger than that in bulk spin crossover Fe{sup 2+} materials. Selective response of {sup 19}F NMR signals on doping with paramagnetic ions demonstrates that NMR can be used as spatially resolved method to study Nafion film with paramagnetic network. Both chemical shift and width of {sup 19}F NMR signals show that SO groups of Nafion, Fe or Co ions, and nitrogen of triazole are bonded whereas they form a spin crossover system. Based on a model of nanosize cylinders proposed for Nafion [K. Schmidt-Rohr and Q. Chen, Nat Mater (2008), 75], we suggest that paramagnetic ions are located inside these cylinders, forming self-assembling magnetically and optically active nanoscale networks.

  7. High-volume use of self-cementing spray dry absorber material for structural applications

    NASA Astrophysics Data System (ADS)

    Riley, Charles E.

    Spray dry absorber (SDA) material, or spray dryer ash, is a byproduct of energy generation by coal combustion and sulfur emissions controls. Like any resource, it ought to be used to its fullest potential offsetting as many of the negative environmental impacts of coal combustion as possible throughout its lifecycle. Its cementitious and pozzolanic properties suggest it be used to augment or replace another energy and emissions intensive product: Portland cement. There is excellent potential for spray dryer ash to be used beneficially in structural applications, which will offset CO2 emissions due to Portland cement production, divert landfill waste by further utilizing a plentiful coal combustion by-product, and create more durable and sustainable structures. The research into beneficial use applications for SDA material is relatively undeveloped and the material is highly underutilized. This dissertation explored a specific self-cementing spray dryer ash for use as a binder in structural materials. Strength and stiffness properties of hydrated spray dryer ash mortars were improved by chemical activation with Portland cement and reinforcement with polymer fibers from automobile tire recycling. Portland cement at additions of five percent of the cementitious material was found to function effectively as an activating agent for spray dryer ash and had a significant impact on the hardened properties. The recycled polymer fibers improved the ductility and toughness of the material in all cases and increased the compressive strength of weak matrix materials like the pure hydrated ash. The resulting hardened materials exhibited useful properties that were sufficient to suggest that they be used in structural applications such as concrete, masonry block, or as a hydraulic cement binder. While the long-term performance characteristics remain to be investigated, from an embodied-energy and carbon emissions standpoint the material investigated here is far superior to

  8. Thermally-Resilient, Broadband Optical Absorber from UV-to-IR Derived from Carbon Nanostructures and Method of Making the Same

    NASA Technical Reports Server (NTRS)

    Kaul, Anupama B. (Inventor); Coles, James B. (Inventor)

    2015-01-01

    A monolithic optical absorber and methods of making same. The monolithic optical absorber uses an array of mutually aligned carbon nanotubes that are grown using a PECVD growth process and a structure that includes a conductive substrate, a refractory template layer and a nucleation layer. Monolithic optical absorbers made according to the described structure and method exhibit high absorptivity, high site densities (greater than 10.sup.9 nanotubes/cm.sup.2), very low reflectivity (below 1%), and high thermal stability in air (up to at least 400.degree. C.). The PECVD process allows the application of such absorbers in a wide variety of end uses.

  9. Optical properties of photochromic and thermochromic materials

    NASA Astrophysics Data System (ADS)

    Mo, Yeon-Gon

    The optical properties of some thin film materials can be altered by an external stimulus. Photochromic and thermochromic materials, including inorganic and organic substances, have optical properties that can be changed in a reversible manner by irradiation and temperature respectively. These materials can be used in applications such as radiation or thermal sensors, information storage devices and smart window applications in buildings and cars. In this work, major effort was concentrated on passive thermal control coatings based on photochromic and thermochromic materials. The inorganic photochromic materials were based on tungsten and molybdenum oxide films and the organic photochromic materials included spiropyrans and spirooxazines. In addition, photochromic composite organic-inorganic films and thermochromic vanadium oxide films were prepared. The samples were synthesized using sputtering, sol-gel process, and thermal oxidation. The optical properties were investigated for the first time by ultraviolet/visible/infrared (UV/VIS/IR) spectroscopic ellipsometry, attenuated total reflection (ATR) infrared ellipsometry, spectrophotometry, and X-ray diffraction (XRD). For amorphous oxide films, the oxygen deficiency was important in determining the photochromic properties of the films. In the mid-infrared region, no photochromism was observed for the films. The optical properties of organic-inorganic composite films changed in the VIS/NIR wavelength region markedly in a reversible process, with UV irradiation. The composite films containing tungsten heteropolyoxometalate (HPOM) showed faster coloration and bleaching than pure tungsten oxide films. The composite films with molybdenum HPOM showed faster coloration and much slower bleaching than tungsten HPOM. The spiropyran and spirooxazine doped polymeric films were investigated for the first time using infrared and ATR ellipsometry. The infrared optical functions obtained by ATR measurements were a little smaller

  10. Neutron-Absorbing Coatings for Safe Storage of Fissile Materials with Enhanced Shielding & Criticality Safety

    SciTech Connect

    Choi, J; Farmer, J; Lee, C; Fischer, L; Boussoufi, M; Liu, B; Egbert, H

    2007-07-03

    Neutron-absorbing Fe-based amorphous-metal coatings have been developed that are more corrosion resistant than other criticality-control materials, including Al-B{sub 4}C composites, borated stainless steels, and Ni-Cr-Mo-Gd alloys. The presence of relatively high concentration of boron in these coatings not only enhances its neutron-absorption capability, but also enables these coatings to exist in the amorphous state. Exceptional corrosion resistance has been achieved with these Fe-based amorphous-metal alloys through additions of chromium, molybdenum, and tungsten. The addition of rare earth elements such as yttrium has lowered the critical cooling rate of these materials, thereby rendering them more easily processed. Containers used for the storage of nuclear materials, and protected from corrosion through the application of amorphous metal coatings, would have greatly enhanced service lives, and would therefore provide greater long-term safety. Amorphous alloy powders have been successfully produced in multi-ton quantities with gas atomization, and applied to several half-scale spent fuel storage containers and criticality control structures with the high-velocity oxy-fuel (HVOF) thermal spray process. Salt fog testing and neutron radiography of these prototypes indicates that such an approach is viable for the production of large-scale industrial-scale facilities and containers. The use of these durable neutron-absorbing materials to coat stainless steel containers and storage racks, as well as vaults, hot-cell facilities and glove boxes could substantially reduce the risk of criticality in the event of an accident. These materials are particularly attractive for shielding applications since they are fire proof. Additionally, layers of other cold and thermal sprayed materials that include carbon and/or carbides can be used in conjunction with the high-boron amorphous metal coatings for the purpose of moderation. For example, various carbides, including boron

  11. Optical substrate materials for synchrotron radiation beamlines

    SciTech Connect

    Howells, M.R.; Paquin, R.A.

    1997-06-01

    The authors consider the materials choices available for making optical substrates for synchrotron radiation beam lines. They find that currently the optical surfaces can only be polished to the required finish in fused silica and other glasses, silicon, CVD silicon carbide, electroless nickel and 17-4 PH stainless steel. Substrates must therefore be made of one of these materials or of a metal that can be coated with electroless nickel. In the context of material choices for mirrors they explore the issues of dimensional stability, polishing, bending, cooling, and manufacturing strategy. They conclude that metals are best from an engineering and cost standpoint while the ceramics are best from a polishing standpoint. They then give discussions of specific materials as follows: silicon carbide, silicon, electroless nickel, Glidcop{trademark}, aluminum, precipitation-hardening stainless steel, mild steel, invar and superinvar. Finally they summarize conclusions and propose ideas for further research.

  12. Molecular Dynamics of a Water-Absorbent Nanoscale Material Based on Chitosan.

    PubMed

    Borca, Carlos H; Arango, Carlos A

    2016-04-21

    Although hydrogels have been widely investigated for their use in materials science, nanotechnology, and novel pharmaceuticals, mechanistic details explaining their water-absorbent features are not well understood. We performed an all-atom molecular dynamics study of the structural transformation of chitosan nanohydrogels due to water absorption. We analyzed the conformation of dry, nanoscaled chitosan, the structural modifications that emerge during the process of water inclusion, and the dynamics of this biopolymer in the presence of nature's solvent. Two sets of nanoscaled, single-chained chitosan models were simulated: one to study the swelling dependence upon the degree of self-cross-linking and other to observe the response with respect to the degree of protonation. We verified that nanohydrogels keep their ability to absorb water and grow, regardless of their degree of cross-linking. Noteworthy, we found that the swelling behavior of nanoscaled chitosan is pH-dependent, and it is considerably more limited than that of larger scale hydrogels. Thus, our study suggests that properties of nanohydrogels are significantly different from those of larger hydrogels. These findings might be important in the design of novel controlled-release and targeted drug-delivery systems based on chitosan.

  13. Optical theory of partially coherent thin-film energy-absorbing structures for power detectors and imaging arrays.

    PubMed

    Withington, Stafford; Thomas, Christopher N

    2009-06-01

    Free-space power detectors often have energy absorbing structures comprising multilayer systems of patterned thin films. We show that for any system of interacting resistive films, the expectation value of the absorbed power is given by the contraction of two tensor fields: one describes the spatial state of coherence of the incoming radiation, the other the state of coherence to which the detector is sensitive. Equivalently, the natural modes of the optical field scatter power into the natural modes of the detector. We describe a procedure for determining the amplitude, phase, and polarization patterns of a detector's optical modes and their relative responsivities. The procedure gives the state of coherence of the currents flowing in the system and leads to important conceptual insights into the way the pixels of an imaging array interact and extract information from an optical field.

  14. Nonlinear optical and conductive polymeric material

    DOEpatents

    Barton, T.J.; Ijadi-Maghsooodi, S; Yi Pang.

    1993-10-19

    A polymeric material is described which exhibits nonlinear optical properties if undoped and conductive properties if doped. The polymer is prepared by polymerizing diethynylsilane compositions, the resulting polymeric material having a weight average molecular weight between about 20,000 and about 200,000 grams per mole. The polymer is prepared and catalytically polymerized by exposure to a catalyst, such as MoCl[sub 5] or W(CO)[sub 6].

  15. Nonlinear optical and conductive polymeric material

    DOEpatents

    Barton, Thomas J.; Ijadi-Maghsoodi, Sina; Pang, Yi

    1992-05-19

    A polymeric material which exhibits nonlinear optical properties if undoped and conductive properties if doped. The polymer is prepared by polymerizing diethynylsilane compositions, the resulting polymeric material having a weight average molecular weight between about 20,000 and about 200,000 grams per mole. The polymer is prepared and catalytically polymerized by exposure to a catalyst, such as MoCl.sub.5 or W(CO).sub.6 /hv.

  16. Nonlinear optical and conductive polymeric material

    DOEpatents

    Barton, Thomas J.; Ijadi-Maghsoodi, Sina; Pang, Yi

    1993-10-19

    A polymeric material which exhibits nonlinear optical properties if undoped and conductive properties if doped. The polymer is prepared by polymerizing diethynylsilane compositions, the resulting polymeric material having a weight average molecular weight between about 20,000 and about 200,000 grams per mole. The polymer is prepared and catalytically polymerized by exposure to a catalyst, such as MoCl.sub.5 or W(CO).sub.6 /hv.

  17. Nonlinear optical and conductive polymeric material

    DOEpatents

    Barton, T.J.; Ijadi-Maghsoodi, S.; Pang, Y.

    1992-05-19

    A polymeric material which exhibits nonlinear optical properties if undoped and conductive properties if doped. The polymer is prepared by polymerizing diethynylsilane compositions, the resulting polymeric material having a weight average molecular weight between about 20,000 and about 200,000 grams per mole. The polymer is prepared and catalytically polymerized by exposure to a catalyst, such as MoCl[sub 5] or W(CO)[sub 6]/hv.

  18. Ultra-light weight undamped tuned dynamic absorber for cryogenically cooled infrared electro-optic payload

    NASA Astrophysics Data System (ADS)

    Veprik, Alexander; Babitsky, Vladimir

    2017-04-01

    Attenuation of tonal cryocooler induced vibration in infrared electro-optical payloads may be achieved by using of Tuned Dynamic Absorber (TDA) which is, generally speaking, a passive, weakly damped mass-spring system the resonant frequency of which is precisely matched with the driving frequency. Added TDA results in a favorable modification of the frequency response functions of combined structure. In particular, a favorable antiresonant notch appears at the frequency of tonal excitation along with the adjacent secondary resonance, the width and depth of which along with its closeness to the secondary resonance are strongly dependent on the mass and damping ratios. Using heavier TDA favorably results in wider and deeper antiresonant notch along with increased gap between antiresonant and resonant frequencies. Lowering damping in TDA favorably results in deepening the antiresonant notch. The weight of TDA is usually subjected to tight design constrains. Use of lightweight TDA not only diminishes the attainable performance but also complicates the procedure of frequency matching. Along these lines, even minor frequency deviations may negate the TDA performance and even result in TDA failure in case of resonant build up. The authors are presenting theoretical and practical aspects of designing and constructing ultra-light weight TDA in application to vibration attenuation of electro-optical infrared payload relying on Split Stirling linear cryocooler, the driving frequency of which is fixed and may be accurately tuned and maintained using a digital controller over the entire range of working conditions and lifetime; the lack of mass ratio is compensated by minimizing the damping ratio. In one particular case, in excess of 100-fold vibration attenuation has been achieved by adding as little as 5% to the payload weight.

  19. Optical materials based on molecular nanoparticles.

    PubMed

    Patra, A; Chandaluri, Ch G; Radhakrishnan, T P

    2012-01-21

    A major part of contemporary nanomaterials research is focused on metal and semiconductor nanoparticles, constituted of extended lattices of atoms or ions. Molecular nanoparticles assembled from small molecules through non-covalent interactions are relatively less explored but equally fascinating materials. Their unique and versatile characteristics have attracted considerable attention in recent years, establishing their identity and status as a novel class of nanomaterials. Optical characteristics of molecular nanoparticles capture the essence of their nanoscale features and form the basis of a variety of applications. This review describes the advances made in the field of fabrication of molecular nanoparticles, the wide spectrum of their optical and nonlinear optical characteristics and explorations of the potential applications that exploit their unique optical attributes.

  20. Exploratory Development on Laser and Optical Materials.

    DTIC Science & Technology

    Judd-Ofelt theory, Quantum efficiencies); Laser materials evaluation; Studies of rare-earth doped CdF2, SrF2 , and BaF2 -- (Electroluminescence of semiconducting CdF2, Analyses of the optical spectra of Gd(3+) and Ce(3+)).

  1. Optical response of phase change material for metasurface (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Chu, Cheng Hung; Tseng, Ming Lun; Chen, Jie; Wu, Hui Jun; Wang, Hsiang-Chu; Chen, Ting-Yu; Tsai, Din Ping

    2016-09-01

    Phase change materials are used as the recording layer in optical data storage, electronic storage and nanolithography due to the enormous physical difference between crystalline and amorphous states. In recent years, they are demonstrated to exploit in various tunable plasmonic devices, such as perfect absorber, planar lenses, plasmonic antenna, Fano resonance and so on. However, in these researches, the phase change material merely plays a role as a refractive index switchable substrate. In this paper, we study the intrinsic optical properties of phase change material Ge2Sb2Te5 (GST) in the near-infrared regime. A clear insight into the dipole resonance system of GST is provided. The reflection phase retardation and intensity of each unit cells depending on the phase state and geometry are estimated. Further, we introduce the concept of reconfigurable gradient metasurface, which has different anomalous reflection angles by switching the combination of nanorods with different geometries and phase states. The research has great potential in the area of tunable metamaterial device (metadevice) in the future.

  2. [A new embolic material: super absorbent polymer (SAP) microsphere and its embolic effects].

    PubMed

    Jiaqi, Y; Hori, S; Minamitani, K; Hashimoto, T; Yoshimura, H; Nomura, N; Ishida, T; Fukuda, H; Tomoda, K; Nakamura, H

    1996-01-01

    SAP-Microsphere (sodium acrylic acid-vinyl alcohol copolymer) has the ability to absorb fluids within a few minutes and increase its diameter. Its diameter can also be calibrated. The diameters in ionic contrast material and human serum are 2.1 and 3.5 times larger, respectively, than the original size. It can pass through a microcatheter with an ionic contrast material, and swells at the occluding point into the desired size. It can be recognized under fluoroscopy due to its absorption of contrast material. A total of 10 rabbit kidney embolizations were done followed by resection in 1-14 weeks. Recanalization was absent in all cases. No adhesion to the perirenal tissue was found. Limited reactive change in endothelial cells was found at one week. No changes in the smooth muscle layer were found at any time during the study. Limited infiltration of neutrophil cells was found in perivascular tissue within a period of one week. SAP-Microspheres maintained their spherical shape during a 14-week period. Extensive fibrosis and calcification were found after 4 weeks. SAP-Microspheres are promising as an embolic agent to obtain satisfactory results of embolization therapy.

  3. Combining linear polarization spectroscopy and the Representative Layer Theory to measure the Beer-Lambert law absorbance of highly scattering materials.

    PubMed

    Gobrecht, Alexia; Bendoula, Ryad; Roger, Jean-Michel; Bellon-Maurel, Véronique

    2015-01-01

    Visible and Near Infrared (Vis-NIR) Spectroscopy is a powerful non destructive analytical method used to analyze major compounds in bulk materials and products and requiring no sample preparation. It is widely used in routine analysis and also in-line in industries, in-vivo with biomedical applications or in-field for agricultural and environmental applications. However, highly scattering samples subvert Beer-Lambert law's linear relationship between spectral absorbance and the concentrations. Instead of spectral pre-processing, which is commonly used by Vis-NIR spectroscopists to mitigate the scattering effect, we put forward an optical method, based on Polarized Light Spectroscopy to improve the absorbance signal measurement on highly scattering samples. This method selects part of the signal which is less impacted by scattering. The resulted signal is combined in the Absorption/Remission function defined in Dahm's Representative Layer Theory to compute an absorbance signal fulfilling Beer-Lambert's law, i.e. being linearly related to concentration of the chemicals composing the sample. The underpinning theories have been experimentally evaluated on scattering samples in liquid form and in powdered form. The method produced more accurate spectra and the Pearson's coefficient assessing the linearity between the absorbance spectra and the concentration of the added dye improved from 0.94 to 0.99 for liquid samples and 0.84-0.97 for powdered samples.

  4. Optical Material Characterization Using Microdisk Cavities

    NASA Astrophysics Data System (ADS)

    Michael, Christopher P.

    Since Jack Kilby recorded his "Monolithic Idea" for integrated circuits in 1958, microelectronics companies have invested billions of dollars in developing the silicon material system to increase performance and reduce cost. For decades, the industry has made Moore's Law, concerning cost and transistor density, a self-fulfilling prophecy by integrating technical and material requirements vertically down their supply chains and horizontally across competitors in the market. At recent technology nodes, the unacceptable scaling behavior of copper interconnects has become a major design constraint by increasing latency and power consumption---more than 50% of the power consumed by high speed processors is dissipated by intrachip communications. Optical networks at the chip scale are a potential low-power high-bandwidth replacement for conventional global interconnects, but the lack of efficient on-chip optical sources has remained an outstanding problem despite significant advances in silicon optoelectronics. Many material systems are being researched, but there is no ideal candidate even though the established infrastructure strongly favors a CMOS-compatible solution. This thesis focuses on assessing the optical properties of materials using microdisk cavities with the intention to advance processing techniques and materials relevant to silicon photonics. Low-loss microdisk resonators are chosen because of their simplicity and long optical path lengths. A localized photonic probe is developed and characterized that employs a tapered optical-fiber waveguide, and it is utilized in practical demonstrations to test tightly arranged devices and to help prototype new fabrication methods. A case study in AlxGa1-xAs illustrates how the optical scattering and absorption losses can be obtained from the cavity-waveguide transmission. Finally, single-crystal Er2O3 epitaxially grown on silicon is analyzed in detail as a potential CMOS-compatable gain medium due to its high Er3

  5. 2D Homologous Perovskites as Light-Absorbing Materials for Solar Cell Applications.

    PubMed

    Cao, Duyen H; Stoumpos, Constantinos C; Farha, Omar K; Hupp, Joseph T; Kanatzidis, Mercouri G

    2015-06-24

    We report on the fabrication and properties of the semiconducting 2D (CH3(CH2)3NH3)2(CH3NH3)(n-1)Pb(n)I(3n+1) (n = 1, 2, 3, and 4) perovskite thin films. The band gaps of the series decrease with increasing n values, from 2.24 eV (CH3(CH2)3NH3)2PbI4 (n = 1) to 1.52 eV CH3NH3PbI3 (n = ∞). The compounds exhibit strong light absorption in the visible region, accompanied by strong photoluminescence at room temperature, rendering them promising light absorbers for photovoltaic applications. Moreover, we find that thin films of the semi-2D perovskites display an ultrahigh surface coverage as a result of the unusual film self-assembly that orients the [Pb(n)I(3n+1)](-) layers perpendicular to the substrates. We have successfully implemented this 2D perovskite family in solid-state solar cells, and obtained an initial power conversion efficiency of 4.02%, featuring an open-circuit voltage (V(oc)) of 929 mV and a short-circuit current density (J(sc)) of 9.42 mA/cm(2) from the n = 3 compound. This result is even more encouraging considering that the device retains its performance after long exposure to a high-humidity environment. Overall, the homologous 2D halide perovskites define a promising class of stable and efficient light-absorbing materials for solid-state photovoltaics and other applications.

  6. Polyimide-based electro-optic materials

    NASA Astrophysics Data System (ADS)

    Cahill, Paul A.; Seager, Carl H.; Meinhardt, Michael B.; Beuhler, Allyson J.; Wargowski, David A.; Singer, Kenneth D.; Kowalczyk, Tony C.; Kosc, Tanya Z.

    1993-12-01

    The properties of new, high temperature optical materials based on dye-doped Ultradel 9000D polyimides are presented. Ultradel 9000D is a soluble, pre-imidized, fluorinated polymer with properties optimized for integrated optical applications. When thermally or photochemically cross-linked, it has a Tg approaching 400DEGC and retains excellent optical transparency as measured by both waveguide loss spectroscopy (WLS) and photothermal deflection spectroscopy (PDS). The agreement between WLS and PDS data indicates that losses in polyimides are due to absorption, not scattering. Two thermally stable, donor-acceptor oxazole-based dyes were designed, synthesized, and doped into the polyimide at concentrations up to 25 percent by weight. The Tg of the doped polymers decreased from the neat polymer, but remained above 300DEGC. The effects of doping on the dielectric constant, refractive index, and coefficient of thermal expansion of the polyimide are presented.

  7. Rice straw-wood particle composite for sound absorbing wooden construction materials.

    PubMed

    Yang, Han-Seung; Kim, Dae-Jun; Kim, Hyun-Joong

    2003-01-01

    In this study, rice straw-wood particle composite boards were manufactured as insulation boards using the method used in the wood-based panel industry. The raw material, rice straw, was chosen because of its availability. The manufacturing parameters were: a specific gravity of 0.4, 0.6, and 0.8, and a rice straw content (10/90, 20/80, and 30/70 weight of rice straw/wood particle) of 10, 20, and 30 wt.%. A commercial urea-formaldehyde adhesive was used as the composite binder, to achieve 140-290 psi of bending modulus of rupture (MOR) with 0.4 specific gravity, 700-900 psi of bending MOR with 0.6 specific gravity, and 1400-2900 psi of bending MOR with a 0.8 specific gravity. All of the composite boards were superior to insulation board in strength. Width and length of the rice straw particle did not affect the bending MOR. The composite boards made from a random cutting of rice straw and wood particles were the best and recommended for manufacturing processes. Sound absorption coefficients of the 0.4 and 0.6 specific gravity boards were higher than the other wood-based materials. The recommended properties of the rice straw-wood particle composite boards are described, to absorb noises, preserve the temperature of indoor living spaces, and to be able to partially or completely substitute for wood particleboard and insulation board in wooden constructions.

  8. Materials and optics for solar energy conversion and advanced lighting technology; Proceedings of the Meeting, San Diego, CA, Aug. 19-21, 1986

    SciTech Connect

    Lampert, C.M.; Holly, S.

    1987-01-01

    The present conference encompasses topics in the fields of optical switching materials, photovoltaic materials, holographic films, and solar optical materials, as well as insolation and illumination testing and measurement technologies, light source hardware and applications, novel optical techniques in illumination and lighting, and the production of lighting effects in the entertainment industry. Attention is given to thermochromic and electrochromic materials for optical switching and energy-efficient windows, tin oxide antireflection coatings, holographic solar concentration and greenhouse lighting, long-lived glass mirrors for space, exposure testing of solar absorbers, optical projection equipment, medium and short arc metal halide lamps, and nonimaging optics for illumination.

  9. Transient Radiation Effects in Optical Materials

    DTIC Science & Technology

    1975-04-29

    investigation. These samples were subsequently used to study the optical bleaching of the induced absorption, and the results of these measurements...readily o b. Luminesces at wavelengths greater than 4000 A, with very low efficiency» Since these components are being considered for use in a...specific sys- tem. Of the materials used in this investigation, Suprasil 2 appears to fit these parameters best. In cases where indices of refraction

  10. Laser Window Materials and Optical Coating Science

    DTIC Science & Technology

    1977-08-01

    10 Torr pressure , is presently the favored alternative RAP agent. Comparison studies of optical coatings prepared under conventional high...In principle , the uncoated surface heat also contributes to the first and second slopes but in practice, as discussed in the results in Sec. Ill...jim), CO (5.3 jim), and CO2 (9.27 and 10.6 fi.m). The window materials that are under investigation include selected alkali halides and

  11. Optical Limiting Materials Based on Gold Nanoparticles

    DTIC Science & Technology

    2014-04-30

    AFRL-OSR-VA-TR-2014-0104 OPTICAL LIMITING MATERIALS BASED ON GOLD NANOPARTICLES John Dawson SOUTH CAROLINA RESEARCH FOUNDATION Final Report 04/30...2009; therefore, the award was modified so that her former department chair, John Dawson, became the PI of the award, with Murphy as a subcontract at...Mediated Synthesis to Nanoscale Sculpting,” Curr. Opin. Colloid. Interfac. Sci. 2011, 16, 128-134. • Sivapalan, S. T.; Vella, J. H.; Yang, T. K.; Dalton

  12. Optical pulling of airborne absorbing particles and smut spores over a meter-scale distance with negative photophoretic force

    SciTech Connect

    Lin, Jinda; Hart, Adam G.; Li, Yong-qing

    2015-04-27

    We demonstrate optical pulling of single light-absorbing particles and smut spores in air over a meter-scale distance using a single collimated laser beam based on negative photophoretic force. The micron-sized particles are pulled towards the light source at a constant speed of 1–10 cm/s in the optical pulling pipeline while undergoing transverse rotation at 0.2–10 kHz. The pulled particles can be manipulated and precisely positioned on the entrance window with an accuracy of ∼20 μm, and their chemical compositions can be characterized with micro-Raman spectroscopy.

  13. Active materials for integrated optic applications

    NASA Astrophysics Data System (ADS)

    Hayden, Joseph S.; Funk, David S.; Veasey, David L.; Peters, Philip M.; Sanford, Norman A.

    1999-11-01

    The ability to engineer glass properties through the selection and adjustment of chemical composition continues to make glass a leading material in both active and passive applications. The development of optimal glass compositions for integrated optical applications requires a number of considerations that are often at variance with one another. Of critical importance is that the glass offers compatibility with standard ion exchange technologies, allowing fabrication of guided wave structures. In addition, for application as an active material, the resultant structures must be characterized by absence of inclusions and low absorption at the lasing wavelength, putting demands on both the selection and identity of the raw materials used to prepare the glass. We report on the development of an optimized glass composition for integrated optic applications that combines good laser properties with good chemical durability allowing for a wide range of chemical processing steps to be employed without substrate deterioration. In addition, care was taken during the development of this glass to insure that the selected composition was consistent with manufacturing technology for producing high optical quality glass. We present the properties of the resultant glasses, including results of detailed chemical and laser properties, for use in the design and modeling of active waveguides prepared with these glasses.

  14. Degradation of optical properties of a film-type single-wall carbon nanotubes saturable absorber (SWNT-SA) with an Er-doped all-fiber laser.

    PubMed

    Ryu, Sung Yoon; Kim, Kyung-Soo; Kim, Jungwon; Kim, Soohyun

    2012-06-04

    Single-wall carbon nanotubes (SWNTs) are promising materials for saturable absorbers (SAs) in mode-locked lasers. However it has been widely recognized that the degradation of optical properties of film-type SWNTs used in femtosecond mode-locked lasers limits the achievable long-term stability of such lasers. In this paper, we study the degradation of optical properties of SWNT-SA fabricated as sandwich type using HiPCO SWNTs with an Er-doped all-fiber laser. The thresholds of laser pump power are examined to avoid the damage of the SWNT-SA. Based on the proposed analysis, it is shown that all-fiber laser pulses of 300 fs pulse width, 3.85 mW average output power, 211.7 MW/cm² peak intensity and 69.9 MHz repetition rate can be reliably generated without any significant damage to the SWNT-SA film.

  15. Optics & Materials Science & Technology (OMST) Organization at LLNL

    SciTech Connect

    Suratwala; Tayyab; Nguyen, Hoang; Bude, Jeff; Dylla-Spears, Rebecca

    2016-11-30

    The Optics and Materials Science & Technology (OMST) organization at Lawrence Livermore National Laboratory (LLNL) supplies optics, recycles optics, and performs the materials science and technology to advance optics and optical materials for high-power and high-energy lasers for a variety of missions. The organization is a core capability at LLNL. We have a strong partnership with many optical fabricators, universities and national laboratories to accomplish our goals. The organization has a long history of performing fundamental optical materials science, developing them into useful technologies, and transferring them into production both on-site and off-site. We are successfully continuing this same strategy today.

  16. Optics & Materials Science & Technology (OMST) Organization at LLNL

    ScienceCinema

    Suratwala; Tayyab; Nguyen, Hoang; Bude, Jeff; Dylla-Spears, Rebecca

    2016-12-09

    The Optics and Materials Science & Technology (OMST) organization at Lawrence Livermore National Laboratory (LLNL) supplies optics, recycles optics, and performs the materials science and technology to advance optics and optical materials for high-power and high-energy lasers for a variety of missions. The organization is a core capability at LLNL. We have a strong partnership with many optical fabricators, universities and national laboratories to accomplish our goals. The organization has a long history of performing fundamental optical materials science, developing them into useful technologies, and transferring them into production both on-site and off-site. We are successfully continuing this same strategy today.

  17. Coupling Hollow Fe3O4-Fe Nanoparticles with Graphene Sheets for High-Performance Electromagnetic Wave Absorbing Material.

    PubMed

    Qu, Bin; Zhu, Chunling; Li, Chunyan; Zhang, Xitian; Chen, Yujin

    2016-02-17

    We developed a strategy for coupling hollow Fe3O4-Fe nanoparticles with graphene sheets for high-performance electromagnetic wave absorbing material. The hollow Fe3O4-Fe nanoparticles with average diameter and shell thickness of 20 and 8 nm, respectively, were uniformly anchored on the graphene sheets without obvious aggregation. The minimal reflection loss RL values of the composite could reach -30 dB at the absorber thickness ranging from 2.0 to 5.0 mm, greatly superior to the solid Fe3O4-Fe/G composite and most magnetic EM wave absorbing materials recently reported. Moreover, the addition amount of the composite into paraffin matrix was only 18 wt %.

  18. Optical analysis of CH3NH3Sn x Pb1-x I3 absorbers: a roadmap for perovskite-on-perovskite tandem solar cells.

    PubMed

    Anaya, Miguel; Correa-Baena, Juan P; Lozano, Gabriel; Saliba, Michael; Anguita, Pablo; Roose, Bart; Abate, Antonio; Steiner, Ullrich; Grätzel, Michael; Calvo, Mauricio E; Hagfeldt, Anders; Míguez, Hernán

    2016-08-07

    Organic-inorganic perovskite structures in which lead is substituted by tin are exceptional candidates for broadband light absorption. Herein we present a thorough analysis of the optical properties of CH3NH3Sn x Pb1-x I3 films, providing the field with definitive insights about the possibilities of these materials for perovskite solar cells of superior efficiency. We report a user's guide based on the first set of optical constants obtained for a series of tin/lead perovskite films, which was only possible to measure due to the preparation of optical quality thin layers. According to the Shockley-Queisser theory, CH3NH3Sn x Pb1-x I3 compounds promise a substantial enhancement of both short circuit photocurrent and power conversion efficiency in single junction solar cells. Moreover, we propose a novel tandem architecture design in which both top and bottom cells are made of perovskite absorbers. Our calculations indicate that such perovskite-on-perovskite tandem devices could reach efficiencies over 35%. Our analysis serves to establish the first roadmap for this type of cells based on actual optical characterization data. We foresee that this study will encourage the research on novel near-infrared perovskite materials for photovoltaic applications, which may have implications in the rapidly emerging field of tandem devices.

  19. Incorporation of Integral Fuel Burnable Absorbers Boron and Gadolinium into Zirconium-Alloy Fuel Clad Material

    SciTech Connect

    Sridharan, K.; Renk, T.J.; Lahoda, E.J.; Corradini, M.L

    2004-12-14

    Long-lived fuels require the use of higher enrichments of 235U or other fissile materials. Such high levels of fissile material lead to excessive fuel activity at the beginning of life. To counteract this excessive activity, integral fuel burnable absorbers (IFBA) are added to some rods in the fuel assembly. The two commonly used IFBA elements are gadolinium, which is added as gadolinium-oxide to the UO2 powder, and boron, which is applied as a zirconium-diboride coating on the UO2 pellets using plasma spraying or chemical vapor deposition techniques. The incorporation of IFBA into the fuel has to be performed in a nuclear-regulated facility that is physically separated from the main plant. These operations tend to be very costly because of their small volume and can add from 20 to 30% to the manufacturing cost of the fuel. Other manufacturing issues that impact cost and performance are maintaining the correct levels of dosing, the reduction in fuel melting point due to gadolinium-oxide additions, and parasitic neutron absorption at fuel's end-of-life. The goal of the proposed research is to develop an alternative approach that involves incorporation of boron or gadolinium into the outer surface of the fuel cladding material rather than as an additive to the fuel pellets. This paradigm shift will allow for the introduction of the IFBA in a non-nuclear regulated environment and will obviate the necessity of additional handling and processing of the fuel pellets. This could represent significant cost savings and potentially lead to greater reproducibility and control of the burnable fuel in the early stages of the reactor operation. The surface alloying is being performed using the IBEST (Ion Beam Surface Treatment) process developed at Sandia National Laboratories. IBEST involves the delivery of energetic ion beam pulses onto the surface of a material, near-surface melting, and rapid solidification. The non-equilibrium nature of such processing allows for surface

  20. Interaction of Electromagnetic Waves with Two-Dimensional Metal Covered with Radar Absorbing Material and Plasma

    NASA Astrophysics Data System (ADS)

    Lan, Chaohui; Hu, Xiwei; Jiang, Zhonghe

    2008-12-01

    A two-dimensional metal model is established to investigate the stealth mechanisms of radar absorbing material (RAM) and plasma when they cover the model together. Using the finite-difference time-domain (FDTD) method, the interaction of electromagnetic (EM) waves with the model can be studied. In this paper, three covering cases are considered: a. RAM or plasma covering the metal solely; b. RAM and plasma covering the metal, while plasma is placed outside; c. RAM and plasma covering the metal, while RAM is placed outside. The calculated results show that the covering order has a great influence on the absorption of EM waves. Compared to case a, case b has an advantage in the absorption of relatively high-frequency EM waves (HFWs), whereas case c has an advantage in the absorption of relatively low-frequency EM waves (LFWs). Through the optimization of the parameters of both plasma and RAM, it is hopeful to obtain a broad absorption band by RAM and plasma covering. Near-field attenuation rate and far-field radar cross section (RCS) are employed to compare the different cases.

  1. A Novel, Real-Valued Genetic Algorithm for Optimizing Radar Absorbing Materials

    NASA Technical Reports Server (NTRS)

    Hall, John Michael

    2004-01-01

    A novel, real-valued Genetic Algorithm (GA) was designed and implemented to minimize the reflectivity and/or transmissivity of an arbitrary number of homogeneous, lossy dielectric or magnetic layers of arbitrary thickness positioned at either the center of an infinitely long rectangular waveguide, or adjacent to the perfectly conducting backplate of a semi-infinite, shorted-out rectangular waveguide. Evolutionary processes extract the optimal physioelectric constants falling within specified constraints which minimize reflection and/or transmission over the frequency band of interest. This GA extracted the unphysical dielectric and magnetic constants of three layers of fictitious material placed adjacent to the conducting backplate of a shorted-out waveguide such that the reflectivity of the configuration was 55 dB or less over the entire X-band. Examples of the optimization of realistic multi-layer absorbers are also presented. Although typical Genetic Algorithms require populations of many thousands in order to function properly and obtain correct results, verified correct results were obtained for all test cases using this GA with a population of only four.

  2. Organosilicon Polymeric Nonlinear Optical Materials for Optical Switching and Modulation

    DTIC Science & Technology

    1994-02-28

    replaced with neat DMSO. Also potassium carbonate (K2CO3) was used as the base, instead of sodium hydroxide (NaOH). Synthesis of ASD-D03 The NLO dye used in...by sublimation. The optically clear films exhibited some microscopic cracks , which could probably be prevented by further process optimization, or...the use of a more crack resistant Accuglass host such as the T-14 series of materials [3]. We now describe the work on the temporally stable nonlinear

  3. Optical detection of cracks in translucent materials

    SciTech Connect

    Petrosky, E.J.; Meeks, R.F.

    1982-03-30

    The qualitative determination of macroscopic and microscopic cracking in ferroelectric ceramics and other translucent materials is achieved by observing the attenuation of light across internal fracture planes within the material. The study was performed on ferroelectric and ceramic disks up to 0.5 in. thick. The microscopic equipment used was an Olympus Vanox Microscope fitted with a vertical brightfield illuminator, polarizer, rotatable analyzer and a quartz-halogen light source. Macroscopic inspection was made with a typical laboratory quartz-halogen illuminator equipped with a fiber-optic light guide. It is shown that inspection by internal lighting using polarized light is a highly effective means for the nondestructive determination of microscopic and macroscopic cracking in translucent materials.

  4. [Design and Preparation of Plant Bionic Materials Based on Optical and Infrared Features Simulation].

    PubMed

    Jiang, Xiao-jun; Lu, Xu-liang; Pan, Jia-liang; Zhang, Shuan-qin

    2015-07-01

    Due to the life characteristics such as physiological structure and transpiration, plants have unique optical and infrared features. In the optical band, because of the common effects of chlorophyll and water, plant leafs show spectral reflectance characteristics change in 550, 680, 1400 and 1900 nm significantly. In the infrared wave band, driven by transpiration, plants could regulate temperature on their own initiative, which make the infrared characteristics of plants different from artificial materials. So palnt bionic materials were proposed to simulate optical and infrared characteristics of plants. By analyzing formation mechanism of optical and infrared features about green plants, the component design and heat-transfer process of plants bionic materials were studied, above these the heat-transfer control formulation was established. Based on water adsorption/release compound, optical pigments and other man-made materials, plant bionic materials preparation methods were designed which could simulate the optical and infrared features of green plants. By chemical casting methods plant bionic material films were prepared, which use polyvinyl alcohol as film forming and water adsorption/release compound, and use optical pigments like chrome green and macromolecule yellow as colouring materials. The research conclusions achieved by testings figured out: water adsorption/release testing showed that the plant bionic materials with a certain thickness could absorb 1.3 kg water per square meter, which could satisfy the water usage of transpiration simulation one day; the optical and infrared simulated effect tests indicated that the plant bionic materials could preferably simulate the spectral reflective performance of green plants in optical wave band (380-2500 nm, expecially in 1400 and 1900 nm which were water absorption wave band of plants), and also it had similar daily infrared radiation variations with green plants, daily average radiation temperature

  5. The Effects of an Absorbing Smoke Layer on MODIS Marine Boundary Layer Cloud Optical Property Retrievals and Radiative Forcing

    NASA Technical Reports Server (NTRS)

    Meyer, Kerry; Platnick, Steven

    2012-01-01

    Clouds, aerosols, and their interactions are widely considered to be key uncertainty components in our current understanding of the Earth's atmosphere and radiation budget. The work presented here is focused on the quasi-permanent marine boundary layer . (MBL) clouds off the southern Atlantic coast of Africa and the effects on MODIS cloud optical property retrievals (MOD06) of an overlying absorbing smoke layer. During much of August and September, a persistent smoke layer resides over this region, produced from extensive biomass burning throughout the southern African savanna. The resulting absorption, which increases with decreasing wavelength, potentially introduces biases into the MODIS cloud optical property retrievals of the underlying MBL clouds. This effect is more pronounced in the cloud optical thickness retrievals, which over ocean are derived from the wavelength channel centered near 0.86 micron (effective particle size retrievals are derived from the longer-wavelength near-IR channels at 1.6, 2.1, and 3.7 microns). Here, the spatial distributions of the scalar statistics of both the cloud and aerosol layers are first determined from the CALIOP 5 km layer products. Next, the MOD06 look-up tables (LUTs) are adjusted by inserting an absorbing smoke layer of varying optical thickness over the cloud. Retrievals are subsequently performed for a subset of MODIS pixels collocated with the CALIOP ground track, using smoke optical thickness from the CALIOP 5km aerosol layer product to select the appropriate LUT. The resulting differences in cloud optical property retrievals due to the inclusion of the smoke layer in the LUTs will be examined. In addition, the direct radiative forcing of this smoke layer will be investigated from the perspective of the cloud optical property retrieval differences.

  6. Effects of ionizing radiation on selected optical materials: An overview

    SciTech Connect

    Wirtenson, G.R.; White, R.H.

    1992-07-30

    This report gives an overview of the effects of ionizing radiation on optical materials that may be used in spacecraft sensors. It introduces the relevant phenomena and indicates were more detailed information can be found. The topics covered include radiation induced absorption in ultraviolet transmitting materials, ordinary optical glasses, cerium stabilized optical glasses, and infrared transmitting materials; bleaching and annealing, and radioluminesence.

  7. Wheeler-Feynman absorber revisited: a useful technique to calculate decay rates and lifetimes in small scale optical systems

    NASA Astrophysics Data System (ADS)

    Venkatapathi, Murugesan

    2011-05-01

    The Wheeler-Feynman (WF) absorber theory of radiation though no more of interest in explaining self interaction of an electron, can be very useful in today's research in small scale optical systems. The significance of the WF absorber is the use of time-symmetrical solution of Maxwell's equations as opposed to only the retarded solution. The radiative coupling of emitters to nano wires in the near field and change in their lifetimes due to small mode volume enclosures have been elucidated with the retarded solutions before. These solutions have also been shown to agree with quantum electrodynamics, thus allowing for classical electromagnetic approaches in such problems. It is here assumed that the radiative coupling of the emitter with a body is in proportion to its contribution to the classical force of radiative reaction as derived in the WF absorber theory. Representing such nano structures as a partial WF absorber acting on the emitter makes the computations considerably easier than conventional electromagnetic solutions for full boundary conditions.

  8. Effect of reference spectra in spectral fitting to discriminate enzyme-activatable photoacoustic probe from intrinsic optical absorbers

    NASA Astrophysics Data System (ADS)

    Hirasawa, Takeshi; Okawa, Shinpei; Iwatate, Ryu J.; Kamiya, Mako; Urano, Yasuteru; Ishihara, Miya

    2016-03-01

    Multispectral photoacoustic (MS-PA) imaging has been researched to image molecular probes in the presence of strong background signals produced from intrinsic optical absorbers. Spectral fitting method (SFM) discriminates probe signals from background signals by fitting the PA spectra that are calculated from MS-PA images to reference spectra of the probe and background, respectively. Because hemoglobin is a dominant optical absorber in visible to near-infrared wavelength range, absorption spectra of hemoglobin have been widely used as reference background spectra. However, the spectra of background signals produced from heterogeneous biological tissue differ from the reference background spectra due to presence of other intrinsic optical absorbers and effect of optical scattering. Due to the difference, the background signals partly remain in the probe images. To image the probe injected in subcutaneous tumors of mice clearly, we added the melanosome absorption spectrum to the reference background spectra because skin contains nonnegligible concentration of melanosome and the spectrum is very similar to the scattering spectrum of biological tissue. The probe injected in the subcutaneous tumor of mice was an enzyme-activatable probe which show their original colors only in the presence of γ-glutamyltranspeptidase, an enzyme associated with cancer. The probes have been successfully used for rapid fluorescence imaging of cancer. As a result of MS-PA imaging, by considering the melanosome absorption spectrum, the background signals were successfully suppressed and then clearer probe image was obtained. Our MS-PA imaging method afforded successful imaging of tumors in mice injected with activatable PA probes.

  9. Study of thermal effects and optical properties of an innovative absorber in integrated collector storage solar water heater

    NASA Astrophysics Data System (ADS)

    Taheri, Yaser; Alimardani, Kazem; Ziapour, Behrooz M.

    2015-10-01

    Solar passive water heaters are potential candidates for enhanced heat transfer. Solar water heaters with an integrated water tank and with the low temperature energy resource are used as the simplest and cheapest recipient devices of the solar energy for heating and supplying hot water in the buildings. The solar thermal performances of one primitive absorber were determined by using both the experimental and the simulation model of it. All materials applied for absorber such as the cover glass, the black colored sands and the V shaped galvanized plate were submerged into the water. The water storage tank was manufactured from galvanized sheet of 0.0015 m in thickness and the effective area of the collector was 0.67 m2. The absorber was installed on a compact solar water heater. The constructed flat-plate collectors were tested outdoors. However the simulation results showed that the absorbers operated near to the gray materials and all experimental results showed that the thermal efficiencies of the collector are over than 70 %.

  10. Yb- and Er-doped fiber laser Q-switched with an optically uniform, broadband WS2 saturable absorber

    PubMed Central

    Zhang, M.; Hu, Guohua; Hu, Guoqing; Howe, R. C. T.; Chen, L.; Zheng, Z.; Hasan, T.

    2015-01-01

    We demonstrate a ytterbium (Yb) and an erbium (Er)-doped fiber laser Q-switched by a solution processed, optically uniform, few-layer tungsten disulfide saturable absorber (WS2-SA). Nonlinear optical absorption of the WS2-SA in the sub-bandgap region, attributed to the edge-induced states, is characterized by 3.1% and 4.9% modulation depths with 1.38 and 3.83 MW/cm2 saturation intensities at 1030 and 1558 nm, respectively. By integrating the optically uniform WS2-SA in the Yb- and Er-doped laser cavities, we obtain self-starting Q-switched pulses with microsecond duration and kilohertz repetition rates at 1030 and 1558 nm. Our work demonstrates broadband sub-bandgap saturable absorption of a single, solution processed WS2-SA, providing new potential efficacy for WS2 in ultrafast photonic applications. PMID:26657601

  11. Yb- and Er-doped fiber laser Q-switched with an optically uniform, broadband WS2 saturable absorber

    NASA Astrophysics Data System (ADS)

    Zhang, M.; Hu, Guohua; Hu, Guoqing; Howe, R. C. T.; Chen, L.; Zheng, Z.; Hasan, T.

    2015-12-01

    We demonstrate a ytterbium (Yb) and an erbium (Er)-doped fiber laser Q-switched by a solution processed, optically uniform, few-layer tungsten disulfide saturable absorber (WS2-SA). Nonlinear optical absorption of the WS2-SA in the sub-bandgap region, attributed to the edge-induced states, is characterized by 3.1% and 4.9% modulation depths with 1.38 and 3.83 MW/cm2 saturation intensities at 1030 and 1558 nm, respectively. By integrating the optically uniform WS2-SA in the Yb- and Er-doped laser cavities, we obtain self-starting Q-switched pulses with microsecond duration and kilohertz repetition rates at 1030 and 1558 nm. Our work demonstrates broadband sub-bandgap saturable absorption of a single, solution processed WS2-SA, providing new potential efficacy for WS2 in ultrafast photonic applications.

  12. [Simultaneous determination of migration amounts of antioxidants and ultraviolet absorbents by high performance liquid chromatography in food contact materials].

    PubMed

    Li, Chengfa; Li, Ying; Chen, Zhinan; Liang, Feng; Chen, Xuhui; Wu, Shaojing; Li, Yongtao; Sun, Xiaoying

    2014-06-01

    An efficient analytical method for the quantitative determination of migration levels of antioxidants and ultraviolet absorbents in food contact materials by high performance liquid chromatography (HPLC) has been developed. The analytical method showed good linearity with the correlation coefficients (r2) > or = 0.999 8 for all the compounds. The limits of detection were between 0.01 mg/L and 0.22 mg/L and the limits of quantification were in the range of 0.03 to 0.85 mg/L for the 23 analytes. According to the European Union Directive No 10/2011, five food simulants were investigated: 30 g/L acetic acid, 10% (v/v) ethanol, 20% (v/v) ethanol, 50% (v/v) ethanol, and fatty food simulant (isooctane). The recoveries were in the range of 92.8%-117.7%, with the relative standard deviations of 0.95%-9.72%. The effects of different experimental conditions on the recoveries of antioxidants and UV absorbents were studied. The results showed that the method is accurate and stable, and can meet the requirements of European Commission Regulation (EU) No 10/2011 and GB 9685-2008 for the specific migration limits (SML) of the antioxidants and ultraviolet absorbents in real food contact plastic materials and article samples. The method has been applied to determine the migration levels of antioxidants and ultraviolet absorbents in different simulants from the migration tests of 30 batches of food contact material samples.

  13. Calculation of the weighting functions for the reconstruction of absorbing inhomogeneities in tissue by time-resolved optical projections

    SciTech Connect

    Konovalov, A B; Vlasov, V V

    2014-08-31

    We report a new method for determining the weighting functions to reconstruct absorbing inhomogeneities in tissue by perturbation time-domain diffuse optical tomography using the transmission geometry of a flat layer. The method is based on an analytical approach to the calculation of the weighting functions for a semi-infinite scattering medium and on the use of the original method of an equivalent inverse source in order to obtain weight distributions for the flat layer geometry. The correctness of the proposed method of the weighting function calculation is evaluated by a numerical experiment on the reconstruction of absorbing inhomogeneities. It is shown that the perturbation reconstruction model based on the proposed weighting function calculation method allows the inhomogeneities smaller than 0.3 cm and ∼0.4 cm, located respectively in the transverse and longitudinal directions to the probe light direction, to be resolved in the centre of an 8-cm-thick object. (laser biophotonics)

  14. Optical dynamic deformation measurements at translucent materials.

    PubMed

    Philipp, Katrin; Koukourakis, Nektarios; Kuschmierz, Robert; Leithold, Christoph; Fischer, Andreas; Czarske, Jürgen

    2015-02-15

    Due to their high stiffness-to-weight ratio, glass fiber-reinforced polymers are an attractive material for rotors, e.g., in the aerospace industry. A fundamental understanding of the material behavior requires non-contact, in-situ dynamic deformation measurements. The high surface speeds and particularly the translucence of the material limit the usability of conventional optical measurement techniques. We demonstrate that the laser Doppler distance sensor provides a powerful and reliable tool for monitoring radial expansion at fast rotating translucent materials. We find that backscattering in material volume does not lead to secondary signals as surface scattering results in degradation of the measurement volume inside the translucent medium. This ensures that the acquired signal contains information of the rotor surface only, as long as the sample surface is rough enough. Dynamic deformation measurements of fast-rotating fiber-reinforced polymer composite rotors with surface speeds of more than 300 m/s underline the potential of the laser Doppler sensor.

  15. Analysis of the effect of different absorber materials and loading on the shielding effectiveness of a metallic enclosure

    NASA Astrophysics Data System (ADS)

    Parr, S.; Karcoon, H.; Dickmann, S.; Rambousky, R.

    2015-11-01

    Metallic rooms as part of a complex system, like a ship, are necessarily connected electromagnetically via apertures and cables to the outside. Therefore, their electromagnetic shielding effectiveness (SE) is limited by ventilation openings, cable feed-throughs and door gaps. Thus, electronic equipment inside these rooms is susceptible to outer electromagnetic threats like IEM (Intentional Electromagnetic Interference). Dielectric or magnetic absorber inside such a screened room can be used in order to prevent the SE from collapsing at the resonant frequencies. In this contribution, the effect of different available absorber materials is compared, as well as other properties like weight and workability. Furthermore, parameter variations of the absorber as well as the effect of loading in form of metallic and dielectric structures on the SE are analyzed.

  16. Smart Optical Material Characterization System and Method

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

    Disclosed is a system and method for characterizing optical materials, using steps and equipment for generating a coherent laser light, filtering the light to remove high order spatial components, collecting the filtered light and forming a parallel light beam, splitting the parallel beam into a first direction and a second direction wherein the parallel beam travelling in the second direction travels toward the material sample so that the parallel beam passes through the sample, applying various physical quantities to the sample, reflecting the beam travelling in the first direction to produce a first reflected beam, reflecting the beam that passes through the sample to produce a second reflected beam that travels back through the sample, combining the second reflected beam after it travels back though the sample with the first reflected beam, sensing the light beam produced by combining the first and second reflected beams, and processing the sensed beam to determine sample characteristics and properties.

  17. Development of FeCoB/Graphene Oxide based microwave absorbing materials for X-Band region

    NASA Astrophysics Data System (ADS)

    Das, Sukanta; Chandra Nayak, Ganesh; Sahu, S. K.; Oraon, Ramesh

    2015-06-01

    This work explored the microwave absorption capability of Graphene Oxide and Graphene Oxide coated with FeCoB for stealth technology. Epoxy based microwave absorbing materials were prepared with 30% loading of Graphene Oxide, FeCoB alloy and Graphene Oxide coated with FeCoB. Graphene Oxide and FeCoB were synthesized by Hummer's and Co-precipitation methods, respectively. The filler particles were characterized by FESEM, XRD and Vibrating Sample Magnetometer techniques. Permittivity, permeability and reflection loss values of the composite absorbers were measured with vector network analyzer which showed a reflection loss value of -7.86 dB, at 10.72 GHz, for single layered Graphene Oxide/Epoxy based microwave absorbers which can be correlated to the absorption of about 83.97% of the incident microwave energy. Reflection loss value of FeCoB/Epoxy based microwave absorber showed -13.30 dB at 11.67 GHz, which corresponded to maximum absorption of 93.8%. However, reflection loss values of Graphene Oxide coated with FeCoB/Epoxy based single-layer absorber increased to -22.24 dB at 12.4 GHz which corresponds to an absorption of 99% of the incident microwave energy.

  18. Evaluating a novel application of optical fibre evanescent field absorbance: rapid measurement of red colour in winegrape homogenates

    NASA Astrophysics Data System (ADS)

    Lye, Peter G.; Bradbury, Ronald; Lamb, David W.

    Silica optical fibres were used to measure colour (mg anthocyanin/g fresh berry weight) in samples of red wine grape homogenates via optical Fibre Evanescent Field Absorbance (FEFA). Colour measurements from 126 samples of grape homogenate were compared against the standard industry spectrophotometric reference method that involves chemical extraction and subsequent optical absorption measurements of clarified samples at 520 nm. FEFA absorbance on homogenates at 520 nm (FEFA520h) was correlated with the industry reference method measurements of colour (R2 = 0.46, n = 126). Using a simple regression equation colour could be predicted with a standard error of cross-validation (SECV) of 0.21 mg/g, with a range of 0.6 to 2.2 mg anthocyanin/g and a standard deviation of 0.33 mg/g. With a Ratio of Performance Deviation (RPD) of 1.6, the technique when utilizing only a single detection wavelength, is not robust enough to apply in a diagnostic sense, however the results do demonstrate the potential of the FEFA method as a fast and low-cost assay of colour in homogenized samples.

  19. The Need For Better Optical Materials

    NASA Astrophysics Data System (ADS)

    Bennett, H. E.

    1984-12-01

    Significant improvements in optical materials have been made in the past 15 years: infrared transmitting windows such as KC1 or ZnSe having absorption coefficients two to three orders of magnitude lower than that previously achievable, infrared transmitting fibers with losses as low as 10 dB/km, inexpensive wide-band antireflective surfaces with reflectance coefficients as low as 0.001, sapphire-like mechanical and thermal properties in a cubic and, hence, nonbirefringent crystal structure called ALON, large hot-pressed spinel structures with good transparency, the list goes on and on. Why then do we still insist on better optical materials? The reasons are as varied as is modern technology, and many of the applications are in quite unrelated fields. Let me outline here just a few of the reasons which I am particularly acquainted with. I speak from a Department of Defense background. Many of the drivers for technology development and a significant amount of the development money (although, unfortunately, usually not enough to cover all that needs to be done) comes from defense-related efforts. What are some of these drivers, and to what directions do they point for additional development?

  20. Femtosecond laser polishing of optical materials

    NASA Astrophysics Data System (ADS)

    Taylor, Lauren L.; Qiao, Jun; Qiao, Jie

    2015-10-01

    Technologies including magnetorheological finishing and CNC polishing are commonly used to finish optical elements, but these methods are often expensive, generate waste through the use of fluids or abrasives, and may not be suited for specific freeform substrates due to the size and shape of finishing tools. Pulsed laser polishing has been demonstrated as a technique capable of achieving nanoscale roughness while offering waste-free fabrication, material-specific processing through direct tuning of laser radiation, and access to freeform shapes using refined beam delivery and focusing techniques. Nanosecond and microsecond pulse duration radiation has been used to perform successful melting-based polishing of a variety of different materials, but this approach leads to extensive heat accumulation resulting in subsurface damage. We have experimentally investigated the ability of femtosecond laser radiation to ablate silicon carbide and silicon. By substituting ultrafast laser radiation, polishing can be performed by direct evaporation of unwanted surface asperities with minimal heating and melting, potentially offering damage-free finishing of materials. Under unoptimized laser processing conditions, thermal effects can occur leading to material oxidation. To investigate these thermal effects, simulation of the heat accumulation mechanism in ultrafast laser ablation was performed. Simulations have been extended to investigate the optimum scanning speed and pulse energy required for processing various substrates. Modeling methodologies and simulation results will be presented.

  1. Vector soliton fiber laser passively mode locked by few layer black phosphorus-based optical saturable absorber.

    PubMed

    Song, Yufeng; Chen, Si; Zhang, Qian; Li, Lei; Zhao, Luming; Zhang, Han; Tang, Dingyuan

    2016-11-14

    We report on the optical saturable absorption of few-layer black phosphorus nanoflakes and demonstrate its application for the generation of vector solitons in an erbium-doped fiber laser. By incorporating the black phosphorus nanoflakes-based saturable absorber (SA) into an all-fiber erbium-doped fiber laser cavity, we are able to obtain passive mode-locking operation with soliton pulses down to ~670 fs. The properties and dynamics of the as-generated vector solitons are experimentally investigated. Our results show that BP nanoflakes could be developed as an effective SA for ultrashort pulse fiber lasers, particularly for the generation of vector soliton pulses in fiber lasers.

  2. Structural and optical properties of copper zinc tin sulphide (CZTS) material synthesized using binary sulphide precursors

    NASA Astrophysics Data System (ADS)

    Patel, K. K.; Shah, D. V.; Kheraj, Vipul

    2013-02-01

    Copper Zinc Tin Sulphide (CZTS) is one of the most promising materials for absorber layer in thin film solar cells. However, the synthesis of CZTS requires careful optimization as it is a quaternary material with a high probability of formation of secondary phases during the synthesis. Here we report the synthesis of CZTS from its binary constituents i.e. CuS, SnS and ZnS at 1030 K in laboratory. The effects of excess sulphur in starting precursors on the chemical compositions of the compound are investigated. Structural and optical properties of synthesized compound are studied in context of its application as absorber material in thin film solar cells.

  3. Optical Characterization of Window Materials for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Tedjojuwono, Ken K.; Clark, Natalie; Humphreys, William M., Jr.

    2013-01-01

    An optical metrology laboratory has been developed to characterize the optical properties of optical window materials to be used for aerospace applications. Several optical measurement systems have been selected and developed to measure spectral transmittance, haze, clarity, birefringence, striae, wavefront quality, and wedge. In addition to silica based glasses, several optical lightweight polymer materials and transparent ceramics have been investigated in the laboratory. The measurement systems and selected empirical results for non-silica materials are described. These measurements will be used to form the basis of acceptance criteria for selection of window materials for future aerospace vehicle and habitat designs.

  4. Optical characterization of window materials for aerospace applications

    NASA Astrophysics Data System (ADS)

    Tedjojuwono, Ken K.; Clark, Natalie; Humphreys, William M.

    2013-09-01

    An optical metrology laboratory has been developed to characterize the optical properties of optical window materials to be used for aerospace applications. Several optical measurement systems have been selected and developed to measure spectral transmittance, haze, clarity, birefringence, striae, wavefront quality, and wedge. In addition to silica based glasses, several optical lightweight polymer materials and transparent ceramics have been investigated in the laboratory. The measurement systems and selected empirical results for non-silica materials are described. These measurements will be used to form the basis of acceptance criteria for selection of window materials for future aerospace vehicle and habitat designs.

  5. Optical techniques for determining dynamic material properties

    SciTech Connect

    Paisley, D.L.; Stahl, D.B.

    1996-12-31

    Miniature plates are laser-launched with a 10-Joule Nd:YAG for one-dimensional (1-D) impacts on to target materials much like gas gun experiments and explosive plane wave plate launch. By making the experiments small, flyer plates (3 mm diameter x 50 micron thick) and targets (10 mm diameter x 200 micron thick), 1-D impact experiments can be performed in a standard laser-optical laboratory with minimum confinement and collateral damage. The laser-launched plates do not require the traditional sabot on gas guns nor the explosives needed for explosive planewave lenses, and as a result are much more amenable to a wide variety of materials and applications. Because of the small size very high pressure gradients can be generated with relative ease. The high pressure gradients result in very high strains and strain rates that are not easily generated by other experimental methods. The small size and short shock duration (1 - 20 ns) are ideal for dynamically measuring bond strengths of micron-thick coatings. Experimental techniques, equipment, and dynamic material results are reported.

  6. Electrodynamics analysis on coherent perfect absorber and phase-controlled optical switch.

    PubMed

    Chen, Tianjie; Duan, Shaoguang; Chen, Y C

    2012-05-01

    A coherent perfect absorber is essentially a specially designed Fabry-Perot interferometer, which completely extinguishes the incident coherent light. The one- and two-beam coherent perfect absorbers have been analyzed using classical electrodynamics by considering index matching in layered structures to totally suppress reflections. This approach presents a clear and physically intuitive picture for the principle of operation of a perfect absorber. The results show that the incident beam(s) must have correct phases and amplitudes, and the real and imaginary parts of the refractive indices of the media in the interferometer must satisfy a well-defined relation. Our results are in agreement with those obtained using the S-matrix analysis. However, the results were obtained solely based on the superposition of waves from multiple reflections without invoking the concept of time reversal as does the S-matrix approach. Further analysis shows that the two-beam device can be configured to function as a phase-controlled three-state switch.

  7. Plasmonic Biofoam: A Versatile Optically Active Material.

    PubMed

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

    2016-01-13

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

  8. Passive electro optical materials and applications

    NASA Astrophysics Data System (ADS)

    Diekstall, K.; Gutu-Nelle, A.; Lauckner, J.; Lutz, F.; Mueller, S.; Seibold, G.; Schichl, H.; Volz, H.

    1980-12-01

    Electro-optical ceramics made of lead/lanthanum/zirconates/titanates (PLZT) can be economically manufactured by coprecipitation of the base materials and by vacuum sintering of the sintering of the green blocks. Magnesium additives reduce by half the operating voltage required to achieve an equal contrast ratio. Transparent electrodes deposited by sputtering tin-indium oxide remain transparent up to 2400 nm. The contrast ratio in the scattering mode amounts typically to 100 : 1 at 500 nm and 5 : 1 at 1000 nm, while in the birefrigence mode it amounts typically to 10,000 : 1 at 800 V/mm, at a thickness of 0.4 mm. Functional blocks were designed to demonstrate and test applications: a laser modular; a light intensity attenuator; welding protection goggles; and numerical displays. The first promising results with sputtered thin films indicate future suitability for displays. Multiple light modulators for opto-electronic nonimpact printing presently appear to be the most important application area.

  9. Optical Window Materials For Hypersonic Flow

    NASA Astrophysics Data System (ADS)

    Au, Robert H.

    1989-09-01

    Optical window materials were investigated for infrared sensor systems used in observing ground targets from a hypersonic-glide vehicle. The equilibrium temperature of the window in the glide region depends on the emissivity and varied between 1,370 and 2,250 K. The high temperatures showed that a protective cover over the window is required during the entire glide region of the trajectory. Ejection of the window cover at 70-kft altitude in the terminal region was assumed, resulting in maximum window temperatures of 565 K and 592 K for magnesium oxide and diamond windows, respectively, both 0.8-in thick. The window temperatures for germanium and sapphire were also calculated. Thermal shock, thermal expansion, the effects of the window radiation on the infrared detectors and methods to reduce the hot window problem were examined.

  10. Absorbing aerosols at high relative humidity: closure between hygroscopic growth and optical properties

    NASA Astrophysics Data System (ADS)

    Flores, J. M.; Bar-Or, R. Z.; Bluvshtein, N.; Abo-Riziq, A.; Kostinski, A.; Borrmann, S.; Koren, I.; Rudich, Y.

    2012-01-01

    The extinction coefficient and growth factor of humidified aerosols, at 80% and 90% RH, and at 532 nm and 355 nm wavelengths were measured for size-selected particles for ammonium sulfate, IHSS Pahokee peat (a lightly absorbing humic-like substance proxy), nigrosine (a black dye to model highly absorbing substances), and a mixture of AS and nigrosine. The ratio of the humidified extinction coefficients to the dry (fRHext(%RH, Dry)) was explored. The measured fRHext(%RH, Dry) was compared to theoretical calculations based on Mie theory, using the measured growth factors and assuming homogeneous mixing. The expected complex refractive indices (RIs) using the volume weighted mixing rule were compared to the RIs derived from the extinction measurements. Moreover, the differences between assuming a core-shell structure or a homogeneous mixing of the substances is examined. The laboratory results were used as a basis to model the change in the total extinction, the single scattering albedo (ω), and the asymmetry parameter (g) in the twilight zone of clouds at 355 nm and 532 nm. We found slightly linear to no dependency of fRH(%RH, Dry) with size for absorbing substances in contrast to the decreasing exponential behavior with size for purely scattering substances. However, no discernable difference could be made between the two wavelengths used. Less than 5% differences were found between the real parts of the complex refractive indices derived and those calculated using the volume weighted mixing rule, and the imaginary parts had up to a 20% difference. Moreover, for substances with growth factor less than 1.15 there was, in average, less than 5% difference between the extinction efficiencies calculated using a core-shell model and assuming homogeneous mixing for size parameters less than 2.5. For x>2.5 the differences were greater causing and overestimation of the extinction efficiency (Qext) values if homogenous mixing was assume instead of a core-shell structure. The

  11. Direct optical imaging of structural inhomogeneities in crystalline materials.

    PubMed

    Grigorev, A M

    2016-05-10

    A method for optical imaging of structural inhomogeneities in crystalline materials is proposed, based on the differences in the optical properties of the structural inhomogeneity and the homogeneous material near the fundamental absorption edge of the crystalline material. The method can be used to detect defects in both semiconductors and insulators.

  12. Determination of the optical and the thermal properties of an absorbing medium by using infrared thermometry

    NASA Astrophysics Data System (ADS)

    Yang, Seung-Jin; Baek, Jun-Hyeok; Kim, Seung-Eun; Kwon, Min-Ki; Park, Jong-Rak; Yeom, Dong-Il; Kim, Ji-Sun; Baek, Jin-Young; Kim, Hyung-Sik; Jun, Jae-Hoon; Chung, Soon-Cheol

    2016-12-01

    Spatiotemporal changes in the surface temperature of an absorbing medium irradiated by using 532-nm laser pulses were measured using an infrared camera. Relevant numerical simulations of the heat transfer equation were performed. The simulations showed that the maximum temperature increase was linearly proportional to the absorption coefficient with no dependence on the thermal conductivity and that the decay time constant depended on both the absorption coefficient and the thermal conductivity. The absorption coefficient and the thermal conductivity of the medium were determined by fitting the simulated results for the maximum temperature increase and decay time constant to the measured results.

  13. Wurtzite silicon as a potential absorber in photovoltaics: Tailoring the optical absorption by applying strain

    NASA Astrophysics Data System (ADS)

    Rödl, C.; Sander, T.; Bechstedt, F.; Vidal, J.; Olsson, P.; Laribi, S.; Guillemoles, J.-F.

    2015-07-01

    We present ab initio calculations of the electronic structure and the optical properties of wurtzite Si (Si-IV). We find an indirect band gap of 0.95 eV (Γ5→M1 ) and an optically forbidden direct gap of 1.63 eV (Γ5→Γ10 ), which is due to a backfolding of the L1 state of Si in the diamond structure (Si-I). Optical absorption spectra including excitonic and local-field effects are calculated. Further, the effects of hydrostatic pressure, uniaxial strain, and biaxial strain on the absorption properties are investigated. Biaxial tensile strains enhance the optical absorption of Si-IV in the spectral range which is relevant for photovoltaic applications. High biaxial tensile strains (>4 % ) even transform Si-IV into a direct semiconductor.

  14. A Two-Step Absorber Deposition Approach To Overcome Shunt Losses in Thin-Film Solar Cells: Using Tin Sulfide as a Proof-of-Concept Material System

    SciTech Connect

    Steinmann, Vera; Chakraborty, Rupak; Rekemeyer, Paul H.; Hartman, Katy; Brandt, Riley E.; Polizzotti, Alex; Yang, Chuanxi; Moriarty, Tom; Gradečak, Silvija; Gordon, Roy G.; Buonassisi, Tonio

    2016-08-31

    As novel absorber materials are developed and screened for their photovoltaic (PV) properties, the challenge remains to reproducibly test promising candidates for high-performing PV devices. Many early-stage devices are prone to device shunting due to pinholes in the absorber layer, producing 'false-negative' results. Here, we demonstrate a device engineering solution toward a robust device architecture, using a two-step absorber deposition approach. We use tin sulfide (SnS) as a test absorber material. The SnS bulk is processed at high temperature (400 degrees C) to stimulate grain growth, followed by a much thinner, low-temperature (200 degrees C) absorber deposition. At a lower process temperature, the thin absorber overlayer contains significantly smaller, densely packed grains, which are likely to provide a continuous coating and fill pinholes in the underlying absorber bulk. We compare this two-step approach to the more standard approach of using a semi-insulating buffer layer directly on top of the annealed absorber bulk, and we demonstrate a more than 3.5x superior shunt resistance Rsh with smaller standard error ..sigma..Rsh. Electron-beam-induced current (EBIC) measurements indicate a lower density of pinholes in the SnS absorber bulk when using the two-step absorber deposition approach. We correlate those findings to improvements in the device performance and device performance reproducibility.

  15. Electromagnetic property of SiO2-coated carbonyl iron/polyimide composites as heat resistant microwave absorbing materials

    NASA Astrophysics Data System (ADS)

    Wang, Hongyu; Zhu, Dongmei; Zhou, Wancheng; Luo, Fa

    2015-02-01

    Heat resistant microwave absorbing materials were prepared by compression molding method, using polyimide resin as matrix and SiO2 coated carbonyl iron (CI) as filler. The SiO2 coated CI particles were prepared by Stober process. The microwave absorbing properties and the effect of heat treatment on the electromagnetic properties of SiO2 coated CI/polyimide composites were investigated. When the content of SiO2 coated CI is 60 wt%, the value of minimum reflection loss decreases from -25 dB to -33 dB with the thickness increases from 1.5 mm to 2.1 mm. According to the thermal-gravimetric analyses (TGA) curves, the polyimide matrix can be used at 300 °C for long time. The complex permittivity of the composites slightly increases while the complex permeability almost keeps constant after heat treatment at 300 °C for 10 h, which indicating that the composites can be used at elevated temperature as microwave absorbing materials at the same time have good heat resistance and microwave absorption.

  16. Evidence of bimodal physical properties of intervening, optically thin C III absorbers at z ˜ 2.5

    NASA Astrophysics Data System (ADS)

    Kim, T.-S.; Carswell, R. F.; Ranquist, D.

    2016-03-01

    We present the Voigt profile analysis of 132 intervening C IV+C III components associated with optically thin H I absorbers at 2.1 < z < 3.4 in the 19 high-quality UVES/VLT and HIRES/Keck QSO spectra. For log N_{C I} in [11.7, 14.1], N_{C III} ∝ N_{C IV}^{1.42± 0.11} and < N_{C III}/N_{C {IV} > = 1.0± 0.3 with a negligible redshift evolution. For 54 C IV components tied (aligned) with H I at log N_{H I} in [12.2, 16.0] and log N_{C IV} in [11.8, 13.8], the gas temperature Tb estimated from absorption line widths is well approximated to a Gaussian peaking at log Tb ˜ 4.4 ± 0.3 for log Tb ∈ [3.5, 5.5], with a negligible non-thermal contribution. For 32 of 54 tied H I+C IV pairs, also tied with C III at log N_{C {III} in [11.7, 13.8], we ran both photoionization equilibrium (PIE) and non-PIE (using a fixed temperature Tb) CLOUDY models for the Haardt-Madau QSOs+galaxies 2012 UV background. We find evidence of bimodality in observed and derived physical properties. High-metallicity branch absorbers have a carbon abundance [C/H]temp ≥ -1.0, a line-of-sight length Ltemp ≤ 20 kpc and a total (neutral and ionized) hydrogen volume density log nH,temp ∈ [-4.5, -3.3] and log Tb ∈ [3.9, 4.5]. Low-metallicity branch absorbers have [C/H]temp ≤ -1.0, Ltemp ∈ [20, 480] kpc and log nH,temp ∈ [-5.2, -4.3] and log Tb ˜ 4.5. High-metallicity branch absorbers seem to be originated from extended discs, inner haloes or outflowing gas of intervening galaxies, while low-metallicity absorbers are produced by galactic haloes or the surrounding intergalactic medium filament.

  17. A facile fabrication of chemically converted graphene oxide thin films and their uses as absorber materials for solar cells

    NASA Astrophysics Data System (ADS)

    Adelifard, Mehdi; Darudi, Hosein

    2016-07-01

    There is a great interest in the use of graphene sheets in thin film solar cells with low-cost and good-optoelectronic properties. Here, the production of absorbent conductive reduced graphene oxide (RGO) thin films was investigated. RGO thin films were prepared from spray-coated graphene oxide (GO) layers at various substrate temperature followed by a simple hydrazine-reducing method. The structural, morphological, optical, and electrical characterizations of graphene oxide (GO) and RGO thin films were investigated. X-ray diffraction analysis showed a phase shift from GO to RGO due to hydrazine treatment, in agreement with the FTIR spectra of the layers. FESEM images clearly exhibited continuous films resulting from the overlap of graphene nanosheets. The produced low-cost thin films had high absorption coefficient up to 1.0 × 105 cm-1, electrical resistance as low as 0.9 kΩ/sq, and effective optical band gap of about 1.50 eV, close to the optimum value for solar conversion. The conductive absorbent properties of the reduced graphene oxide thin films would be useful to develop photovoltaic cells.

  18. Unsymmetrical squaraines for nonlinear optical materials

    NASA Technical Reports Server (NTRS)

    Marder, Seth R. (Inventor); Chen, Chin-Ti (Inventor); Cheng, Lap-Tak (Inventor)

    1996-01-01

    Compositions for use in non-linear optical devices. The compositions have first molecular electronic hyperpolarizability (.beta.) either positive or negative in sign and therefore display second order non-linear optical properties when incorporated into non-linear optical devices.

  19. Mechanical and optical characterization of bio-nanocomposite from pineapple leaf fiber material for food packaging

    NASA Astrophysics Data System (ADS)

    Nikmatin, Siti; Rudwiyanti, Jerry R.; Prasetyo, Kurnia W.; Yedi, Dwi A.

    2015-01-01

    The utilization of Bio-nanocomposite material that was derived from pineapple leaf fiber as filler and tapioca starch with plasticizer glycerol as a matrix for food packaging can reduce the use of plastic that usually was made from petroleum materials. It is important to develop and producethis environmental friendly plastic because of limited availability of petroleum nowadays. The process of synthesize and characterization tapioca starch with the plasticizer glycerol bionanocomposites using print method had been conducted. There were 3 samples with different filler concentration variation; 3%, 4% and 5%.The results of mechanical test from each sample showed that bio-nanocomposite with 5% filler concentration was the optimum sample with 4.6320 MPa for tensile strength test and 24.87% for the elongation test. Based on the result of optical test for each sample was gained that along with the increasing of concentration filler would make the absorbance value of the sample became decreased, bio-nanocomposite with 5% filler concentration had several peaks with low absorbance values. The first peak was in 253 nm of wavelength regionwith absorbance of 0.131%, and the second peak was in 343 nmwavelength region and absorbance was 0.087%.

  20. Bistable optical devices with laser diodes coupled to absorbers of narrow spectral bandwidth.

    PubMed

    Maeda, Y

    1994-06-20

    An optical signal inverter was demonstrated with a combination of the following two effects: One is the decrease of the transmission of an Er-doped YAG crystal with increasing red shift of a laser diode resulting from an increase in the injection current, and the other is a negative nonlinear absorption in which the transmission decreases inversely with increasing laser intensity. Because a hysteresis characteristic exists in the relationship between the wavelength and the injection current of the laser diode, an optical bistability was observed in this system.

  1. Optical-Fiber-Based, Time-Resolved Photoluminescence Spectrometer for Thin-Film Absorber Characterization and Analysis of TRPL Data for CdS/CdTe Interface: Preprint

    SciTech Connect

    Kuciauskas, D.; Duenow, J. N.; Kanevce, A.; Li, J. V.; Young, M. R.; Dippo, P.; Levi, D. H.

    2012-06-01

    We describe the design of a time resolved photoluminescence (TRPL) spectrometer for rapid semiconductor absorber characterization. Simplicity and flexibility is achieved by using single optical fiber to deliver laser pulses and to collect photoluminescence. We apply TRPL for characterization of CdS/CdTe absorbers after deposition, CdCl2 treatment, Cu doping, and back contact formation. Data suggest this method could be applied in various stages of PV device processing. Finally, we show how to analyze TRPL data for CdS/CdTe absorbers by considering laser light absorption depth and intermixing at CdS/CdTe interface.

  2. Interior radiances in optically deep absorbing media. 1: Exact solutions for one-dimensional model

    NASA Technical Reports Server (NTRS)

    Kattawar, G. W.; Plass, G. N.

    1973-01-01

    The exact solutions are obtained for a one dimensional model of a scattering and absorbing medium. The results are given for both the reflected and transmitted radiance for any arbitrary surface albedo as well as for the interior radiance. These same quantities are calculated by the matrix operator method. The relative error of the solutions is obtained by comparison with the exact solutions as well as by an error analysis of the equations. The importance of an accurate starting value for the reflection and transmission operators is shown. A fourth order Runge-Kutta method can be used to solve the differential equations satisfied by these operators in order to obtain such accurate starting values.

  3. Development of High Band Gap Absorber and Buffer Materials for Thin Film Solar Cell Applications

    NASA Astrophysics Data System (ADS)

    Dwyer, Dan

    2011-12-01

    CuInGaSe2 (CIGS) device efficiencies are the highest of the thin film absorber materials (vs. CdTe, alpha-Si, CuInSe2). However, the band gap of the highest efficiency CIGS cells deviates from the expected ideal value predicted by models [1]. Widening the band gap to the theoretically ideal value is one way to increase cell efficiencies. Widening the band gap can be accomplished in two ways; by finding a solution to the Ga-related defects which limit the open circuit voltage at high Ga ratios, or by utilizing different elemental combinations to form an alternative high band gap photoactive Cu-chalcopyrite (which includes any combination of the cations Cu, Al, Ga, and In along with the anions S, Se, and Te). This thesis focuses on the second option, substituting aluminum for gallium in the chalcopyrite lattice to form a CuInAlSe2 (CIAS) film using a sputtering and selenization approach. Both sequential and co-sputtering of metal precursors is performed. Indium was found to be very mobile during both sputtering processes, with a tendency to diffuse to the film surface even when deposited as the base layer in a sequential sputtering process. Elemental diffusion was controlled to a degree using thicker Cu top layer in co-sputtering. The greater thermal conductivity of stainless steel foil (16 W/mK) vs. glass (0.9-1.3 W/mK) can also be used to limit indium diffusion, by keeping the substrate cooler during sputtering. In both sputtering methods aluminum is deposited oxygen-free by capping the film with a Cu capping layer in combination with controlling the indium diffusion. Selenization of metal precursor films is completed using two different techniques. The first is a thermal evaporation approach from a heated box source (method 1 -- reactive thermal evaporation (RTE-Se)). The second is batch selenization using a heated tube furnace (method 2 -- batch selenization). Some batch selenized precursors were capped with ˜ 1mum of selenium. In both selenization methods

  4. Optical band gaps of organic semiconductor materials

    NASA Astrophysics Data System (ADS)

    Costa, José C. S.; Taveira, Ricardo J. S.; Lima, Carlos F. R. A. C.; Mendes, Adélio; Santos, Luís M. N. B. F.

    2016-08-01

    UV-Vis can be used as an easy and forthright technique to accurately estimate the band gap energy of organic π-conjugated materials, widely used as thin films/composites in organic and hybrid electronic devices such as OLEDs, OPVs and OFETs. The electronic and optical properties, including HOMO-LUMO energy gaps of π-conjugated systems were evaluated by UV-Vis spectroscopy in CHCl3 solution for a large number of relevant π-conjugated systems: tris-8-hydroxyquinolinatos (Alq3, Gaq3, Inq3, Al(qNO2)3, Al(qCl)3, Al(qBr)3, In(qNO2)3, In(qCl)3 and In(qBr)3); triphenylamine derivatives (DDP, p-TTP, TPB, TPD, TDAB, m-MTDAB, NPB, α-NPD); oligoacenes (naphthalene, anthracene, tetracene and rubrene); oligothiophenes (α-2T, β-2T, α-3T, β-3T, α-4T and α-5T). Additionally, some electronic properties were also explored by quantum chemical calculations. The experimental UV-Vis data are in accordance with the DFT predictions and indicate that the band gap energies of the OSCs dissolved in CHCl3 solution are consistent with the values presented for thin films.

  5. Characterization of optical material parameters for EUV Lithography applications at PTB

    NASA Astrophysics Data System (ADS)

    Laubis, Christian; Haase, Anton; Soltwisch, Victor; Scholze, Frank

    2015-09-01

    EUV Lithography now reaches the fab floor. The technology ramp up and integration with existing processes will require evolutionary steps in many aspects of the technology. For instance will it be necessary to reduce 3D mask effects like shadowing e.g. by introducing a thinner absorber structure. Continuous progress will be based on using new materials, adapted multilayers, and new reticle designs. Many of these developments are based on simulations and computer models for the design of the required structures and thus require data on the optical properties of the materials involved. In particular when addressing the reticle where the optical function is the target value. Using its more than 25 years of expertise in EUV metrology1, PTB operates instrumentation for reflectometry and scatterometry2 in the EUV and adjacent wavelength ranges and can provide the data for the determination of optical material parameters for individual thin layers. The need for sound optical parameter characterization for the development of alternative EUV materials was thoroughly motivated during the 2015 SPIE Advanced Lithography conference3. The data required is not readily available from databases, as thin film properties - depending on their deposition method and interfaces - may deviate significantly from standard bulk data4. Therefore, better optical constants and a continuous availability of the associated measurement tools are vital for further progress in EUV reticle and optical system design. The ability to vary relevant parameters like wavelength, angle of incidence (AOI), the plane of incidence and polarization is a prerequisite to gather sufficient data to model optical constants. We give details on PTB's measurement capabilities and accessible parameter space for optical material parameter characterization and show some representative data and results.

  6. Composition for absorbing hydrogen

    DOEpatents

    Heung, Leung K.; Wicks, George G.; Enz, Glenn L.

    1995-01-01

    A hydrogen absorbing composition. The composition comprises a porous glass matrix, made by a sol-gel process, having a hydrogen-absorbing material dispersed throughout the matrix. A sol, made from tetraethyl orthosilicate, is mixed with a hydrogen-absorbing material and solidified to form a porous glass matrix with the hydrogen-absorbing material dispersed uniformly throughout the matrix. The glass matrix has pores large enough to allow gases having hydrogen to pass through the matrix, yet small enough to hold the particles dispersed within the matrix so that the hydrogen-absorbing particles are not released during repeated hydrogen absorption/desorption cycles.

  7. Composition for absorbing hydrogen

    DOEpatents

    Heung, L.K.; Wicks, G.G.; Enz, G.L.

    1995-05-02

    A hydrogen absorbing composition is described. The composition comprises a porous glass matrix, made by a sol-gel process, having a hydrogen-absorbing material dispersed throughout the matrix. A sol, made from tetraethyl orthosilicate, is mixed with a hydrogen-absorbing material and solidified to form a porous glass matrix with the hydrogen-absorbing material dispersed uniformly throughout the matrix. The glass matrix has pores large enough to allow gases having hydrogen to pass through the matrix, yet small enough to hold the particles dispersed within the matrix so that the hydrogen-absorbing particles are not released during repeated hydrogen absorption/desorption cycles.

  8. Influence of nanoscale temperature rises on photoacoustic generation: Discrimination between optical absorbers based on thermal nonlinearity at high frequency.

    PubMed

    Simandoux, Olivier; Prost, Amaury; Gateau, Jérôme; Bossy, Emmanuel

    2015-03-01

    In this work, we experimentally investigate thermal-based nonlinear photoacoustic generation as a mean to discriminate between different types of absorbing particles. The photoacoustic generation from solutions of dye molecules and gold nanospheres (same optical densities) was detected using a high frequency ultrasound transducer (20 MHz). Photoacoustic emission was observed with gold nanospheres at low fluence for an equilibrium temperature around 4 °C, where the linear photoacoustic effect in water vanishes, highlighting the nonlinear emission from the solution of nanospheres. The photoacoustic amplitude was also studied as a function of the equilibrium temperature from 2 °C to 20 °C. While the photoacoustic amplitude from the dye molecules vanished around 4 °C, the photoacoustic amplitude from the gold nanospheres remained significant over the whole temperature range. Our preliminary results suggest that in the context of high frequency photoacoustic imaging, nanoparticles may be discriminated from molecular absorbers based on nanoscale temperature rises.

  9. Optical detection of single non-absorbing molecules using the surface plasmon resonance of a gold nanorod

    NASA Astrophysics Data System (ADS)

    Zijlstra, Peter; Paulo, Pedro M. R.; Orrit, Michel

    2012-06-01

    Existing methods for the optical detection of single molecules require the molecules to absorb light to produce fluorescence or direct absorption signals. This limits the range of species that can be detected, because most molecules are purely refractive. Metal nanoparticles or dielectric resonators can be used to detect non-absorbing molecules because local changes in the refractive index produce a resonance shift. However, current approaches only detect single molecules when the resonance shift is amplified by a highly polarizable label or by a localized precipitation reaction on the surface of a nanoparticle. Without such amplification, single-molecule events can only be identified in a statistical way. Here, we report the plasmonic detection of single molecules in real time without the need for labelling or amplification. Our sensor consists of a single gold nanorod coated with biotin receptors, and the binding of single proteins is detected by monitoring the plasmon resonance of the nanorod with a sensitive photothermal assay. The sensitivity of our device is ~700 times higher than state-of-the-art plasmon sensors and is intrinsically limited by spectral diffusion of the surface plasmon resonance.

  10. High Terahertz Absorbing Nanoscale Metal Films for Fabrication of Micromechanical Bi-material THz Sensors

    DTIC Science & Technology

    2010-06-01

    the vacuum cell , when the THz source is off. After the THz illumination, through the lens and the wrapped object, the respective pixels which absorb...placed into the vacuum cell , when the THz source is off. After the THz illumination, through the lens and the wrapped object, the respective pixels...Refraction Index of Silicon Oxide layer % n4=2.05; n5=1.46; n6=2.05; n7=1.46; n8=2.05; n9 =1.46; n10=2.05; n11=1.46; n12=(1-i

  11. High concentration two-stage optics for parabolic trough solar collectors with tubular absorber and large rim angle

    SciTech Connect

    Collares-Pereira, M. ); Gordon, J.M. ); Rabl, A. ); Winston, R. )

    1991-01-01

    A new two-stage optical design is proposed for parabolic trough solar collectors with tubular absorbers. It can boost the concentration ratio by a factor of 2.5 relative to the conventional design, while maintaining the large rim angles (i.e., low nominal f-numbers) that are desirable for practical and economical reasons. The second state involves asymmetric nonimaging concentrators of the CPC type, facing segments of the parabolic first stage. The second stage can be accommodated inside an evacuated receiver, allowing the use of first-surface silvered reflectors. The low heat loss of this design opens the possibility of producing steam at temperatures and pressures of conventional power plants, using only one-axis tracking. The improvement in conversion efficiency would be substantial.

  12. Optical and Terahertz Measurements of Spintronic Materials

    NASA Astrophysics Data System (ADS)

    Bas, Derek A.

    Terahertz time-domain spectroscopy (THz-TDS) is a versatile method to determine lattice, electronic charge and spin dynamics. This dissertation employs THz-TDS to study the spin and charge dynamics in topological insulator and antiferromagnetic systems. Observing time-domain effects on the scale of picoseconds gives unprecedented control over optoelectronic properties. Methods and challenges of THz generation, detection, and transmission are outlined. The wealth of light-matter interactions present in all nonlinear optical experiments are discussed, including primarily optical rectification, shift currents, and injection currents. Each of these gives valuable insight into the carrier dynamics of a material type. Conventional electronics can be improved in their speed and efficiency by taking advantage of an additional degree of freedom- electron spin. Therefore, we consider material types which exhibit great potential to replace common electronic materials while simultaneously employing electron spin for information storage or transport. Antiferromagnets show a type of spin-order that has the ability to store bits without unwanted interactions between neighboring particles. In antiferromagnetic MnF2 which has a Neel temperature of TN = 67 K, THz-TDS is performed on one-magnon and two-magnon resonances in the 0.1-2.3 THz range while varying the temperature from 6 to 295 K. The behavior of the one-magnon resonance is modeled by modified molecular field theory with an additional coupling term j set as a free parameter to fit the data. The resulting best fit value j = 1.1 provides the first experimental evidence indicating that neighboring spins in MnF 2 are only weakly coupled, closely approximating mean-field theory. Time-of-flight analysis was performed on the transmitted THz pulses to measure the temperature-dependent THz refractive index, which was modeled by phonon energy in the T > TN regime and magnetic energy in the T < TN regime. In the range T < 10 K

  13. Systems, Devices, and Materials for Digital Optical Processing.

    NASA Astrophysics Data System (ADS)

    Title, Mark Alan

    The massive parallelism and flexibility of three -dimensional optical communication may allow the development of new parallel computers free from the constraints of planar electronic technology. To bring the optical computer from possibility to reality, however, requires technological and scientific development in new optical systems, devices, and materials. We present here research results in each of these areas. First described is a prototype optical information processing system using CdS/liquid crystal spatial light modulators for optical logic and memory. This system has been developed as the first step in the implementation of a fine-grained, globally-interconnected optical processing element array. Notable system features include the implementation of programmable electronic control and the analysis of the optical power distribution within the processor, both directly applicable to the design of new and more advanced optical information processing systems. Next presented is the design and initial performance data for a new spatial light modulator combining an array of silicon phototransistors with the electro-optic material (Pb,La)(Zr,Ti)O _3, opening new possibilities for "intelligent" optical logic, memory, and switching devices. Important to the optimal performance of this Si/PLZT device is the fabrication of embedded electrodes in the electro-optic material, reducing the device operating voltage and switching energy while improving the uniformity of the optical modulation. An extensive computer model of embedded electrode performance and details of the electrode fabrication by reactive ion beam etching and electroless Ni deposition are presented. Finally, in the area of optical materials development we present initial results in the RF magnetron deposition of electro -optic PLZT on r-plane sapphire. This work is important to the fabrication of a monolithic, Si/PLZT-on-sapphire spatial light modulator, promising superior performance to devices using

  14. Optical studies of dynamical processes in disordered materials

    SciTech Connect

    Yen, W.M.

    1990-12-01

    Our research continues to focus on the study of the structure and the dynamic behavior of insulating solids which can be activated optically. We have been particularly interested in the physical processes which produce relaxation and energy transfer in the optical excited states. Our studies have been based principally on optical laser spectroscopic techniques which reveal a more detailed view of the materials of interest and which will ultimately lead to the development of more efficient optoelectronic materials. 13 refs.

  15. TRANSVERSE MODE ELECTRO-OPTIC MATERIALS.

    DTIC Science & Technology

    electro - optic modulators presently used are crystals such as KDP which exhibit a longitudinal electro - optic effect. It has been demonstrated that a more efficient modulator can be produced when a crystal having a transverse electro - optic effect is employed. Generally these crystals are produced either from the melt or from fluxes. Since melt grown crystals must be cooled through several hundred degrees and often must undergo phase transitions, these crystals are generally highly strained. Flux grown crystals are also

  16. NIF Optical Materials and Fabrication Technologies: An Overview

    SciTech Connect

    Campbell, J H; Hawley-Fedder, R; Stolz, C J; Menapace, J A; Borden, M R; Whitman, P; Yu, J; Runkel, M; Riley, M; Feit, M; Hackel, R

    2004-02-23

    The high-energy/high-power section of the NIF laser system contains 7360 meter-scale optics. Advanced optical materials and fabrication technologies needed to manufacture the NIF optics have been developed and put into production at key vendor sites. Production rates are up to 20 times faster and per-optic costs 5 times lower than could be achieved prior to the NIF. In addition, the optics manufactured for NIF are better than specification giving laser performance better than the design. A suite of custom metrology tools have been designed, built and installed at the vendor sites to verify compliance with NIF optical specifications. A brief description of the NIF optical wavefront specifications for the glass and crystal optics is presented. The wavefront specifications span a continuous range of spatial scale-lengths from 10 {micro}m to 0.5 m (full aperture). We have continued our multi-year research effort to improve the lifetime (i.e. damage resistance) of bulk optical materials, finished optical surfaces and multi-layer dielectric coatings. New methods for post-processing the completed optic to improve the damage resistance have been developed and made operational. This includes laser conditioning of coatings, glass surfaces and bulk KDP and DKDP and well as raster and full aperture defect mapping systems. Research on damage mechanisms continues to drive the development of even better optical materials.

  17. NIF optical materials and fabrication technologies: an overview

    NASA Astrophysics Data System (ADS)

    Campbell, John H.; Hawley-Fedder, Ruth A.; Stolz, Christopher J.; Menapace, Joseph A.; Borden, Michael R.; Whitman, Pamela K.; Yu, June; Runkel, Michael J.; Riley, Michael O.; Feit, Michael D.; Hackel, Richard P.

    2004-05-01

    The high-energy/high-power section of the NIF laser system contains 7360 meter-scale optics. Advanced optical materials and fabrication technologies needed to manufacture the NIF optics have been developed and put into production at key vendor sites. Production rates are up to 20 times faster and per-optic costs 5 times lower than could be achieved prior to the NIF. In addition, the optics manufactured for NIF are better than specification giving laser performance better than the design. A suite of custom metrology tools have been designed, built and installed at the vendor sites to verify compliance with NIF optical specifications. A brief description of the NIF optical wavefront specifications for the glass and crystal optics is presented. The wavefront specifications span a continuous range of spatial scale-lengths from 10 μm to 0.5 m (full aperture). We have continued our multi-year research effort to improve the lifetime (i.e. damage resistance) of bulk optical materials, finished optical surfaces and multi-layer dielectric coatings. New methods for post-processing the completed optic to improve the damage resistance have been developed and made operational. This includes laser conditioning of coatings, glass surfaces and bulk KDP and DKDP and well as raster and full aperture defect mapping systems. Research on damage mechanisms continues to drive the development of even better optical materials.

  18. Optical Spectroscopy of Nano Materials and Structures

    NASA Astrophysics Data System (ADS)

    Guo, Wenhao

    In this thesis, nanostructures and nanomaterials ranging from 3D to OD will be studied compresively, by using optical methods. Firstly, for 3D and 2D nanomaterials, nanoporous zeolite crystals, such as AFI and AEL are introduced as host materials to accommodate diatomic iodine molecules. Polarized Raman spectroscopy is utilized to identify the two configurations of iodine molecules to stay in the channels of AEL: the lying mode (the bond of the two atoms is parallel to the direction of the channels) and the standing mode (the bond is perpendicular to the direction of the channels). The lying mode and standing mode are switchable and can be well controlled by the amount of water molecules inside the crystal, revealed by both molecule dynamics simulation and experiment observation. With more water molecules inside, iodine molecules choose to stay in the standing mode, while with less water molecules, iodine molecules prefer to lie along the channel. Therefore, the configurations of molecules could be precisely controlled, globally by the surrounding pressure and temperature, and locally by the laser light. Ii is believed that this easy and reversible control of single molecule will be valuable in nanostructured devices, such as molecular sieving or molecular detection. Secondly, for 1D case, the PL spectrum of ZnO nanowire under uniaxial strain is studied. When a ZnO nanowire is bent, besides the lattice constant induced bandgap change on the tensile and compressive sides, there is a piezoelectric field generated along the cross section. This piezoelectric potential, together with the bandgap changes induced by the deformation, will redistribute the electrons excited by incident photons from valence band to conduction band. As a result, the electrons occupying the states at the tensile side will largely outnumbered the ones at the compressive side. Therefore, the PL spectrum we collected at the whole cross section will manifest a redshift, other than the peak

  19. Quantitation of absorbed or deposited materials on a substrate that measures energy deposition

    DOEpatents

    Grant, Patrick G.; Bakajin, Olgica; Vogel, John S.; Bench, Graham

    2005-01-18

    This invention provides a system and method for measuring an energy differential that correlates to quantitative measurement of an amount mass of an applied localized material. Such a system and method remains compatible with other methods of analysis, such as, for example, quantitating the elemental or isotopic content, identifying the material, or using the material in biochemical analysis.

  20. Absorbents as packing materials in on-line coupling of reversed phase liquid chromatography and gas chromatography via a programmed temperature vaporizer.

    PubMed

    Flores, Gema; Ruiz Del Castillo, Maria Luisa; Herraiz, Marta

    2007-06-15

    A method based on the use of absorbents as packing materials in the interface of the direct coupling between reversed phase liquid chromatography and gas chromatography (RPLC-GC) is proposed. To that end, a comparative study on different adsorbents and absorbents was carried out. Specifically, Tenax TA and Gaschrom were used as adsorbents while polydimethylsiloxane and poly(50% phenyl:50% methylsiloxane) were the absorbents tested. Some experimental variables involved in the solvent elimination were separately optimised for adsorbent and absorbent materials. Relative standard deviations (RSD) lower than 10% were achieved in all cases but the use of absorbents showed interesting advantages with respect to adsorbents, namely a simpler performance of the experimental work, which facilitates the sample preparation step and the subsequent gas chromatographic analysis to be performed.

  1. Scientific Applications of Optical Instruments to Materials Research

    NASA Technical Reports Server (NTRS)

    Witherow, William K.

    1997-01-01

    Microgravity is a unique environment for materials and biotechnology processing. Microgravity minimizes or eliminates some of the effects that occur in one g. This can lead to the production of new materials or crystal structures. It is important to understand the processes that create these new materials. Thus, experiments are designed so that optical data collection can take place during the formation of the material. This presentation will discuss scientific application of optical instruments at MSFC. These instruments include a near-field scanning optical microscope, a miniaturized holographic system, and a phase-shifting interferometer.

  2. Optical Storage and Retrieval of Library Material.

    ERIC Educational Resources Information Center

    Folen, Doris R.; Stackpole, Laurie E.

    1993-01-01

    Describes the newly installed optical disk storage system at the Naval Research Laboratory's Research Library and Technical Information Center. Planning and design of the system, the conversion of 140,000 reports to optical disk, the information retrieval process, and future plans are covered. (Contains nine references.) (KRN)

  3. [The potential of tone audiometry for the determination of the sound-absorbing properties of various materials].

    PubMed

    Zinkin, V N; Sheshegov, P M

    2014-01-01

    The objective of the present work was to experimentally estimate the potential of the tone audiometry technique for the determination of the sound-absorbing properties of various material. The study included 15 subjects at the age from 19 to 32 years. Their audiological examination was followed by the placement of the 5×7 cm spacer plate from the study material beneath the bone vibrator telephone to determine the bone sound-conduction threshold; no air-marking was undertaken. The sound absorption by the study materials of interest was determined in each octave-band from 250 to 8000 Hz from the difference between the starting audiogram and the audiogram of the material of interest. The study was carried out in three stages: (1) evaluation of sound absorption of each of the five materials, (2) measurement of the same parameter in the combinations of 2--4 layers for increasing sound absorption, and (3) fixation of the bone conduction telephone by the operator's hand (the head-mounted harness was used for the same purpose at stages 1 and 2). The experiments demonstrated that the study of bone sound conduction by means of tone audiometry allows to estimate the sound absorption of various materials. This technique may be applied for the development of a subjective method for the measurement of sound absorption in order to evaluate the acoustic effectiveness of materials that can be used to construct individual protective anti-noise devices.

  4. Corrosion resistant neutron absorbing coatings

    DOEpatents

    Choi, Jor-Shan [El Cerrito, CA; Farmer, Joseph C [Tracy, CA; Lee, Chuck K [Hayward, CA; Walker, Jeffrey [Gaithersburg, MD; Russell, Paige [Las Vegas, NV; Kirkwood, Jon [Saint Leonard, MD; Yang, Nancy [Lafayette, CA; Champagne, Victor [Oxford, PA

    2012-05-29

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  5. Corrosion resistant neutron absorbing coatings

    DOEpatents

    Choi, Jor-Shan; Farmer, Joseph C; Lee, Chuck K; Walker, Jeffrey; Russell, Paige; Kirkwood, Jon; Yang, Nancy; Champagne, Victor

    2013-11-12

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  6. Laser And Nonlinear Optical Materials For Laser Remote Sensing

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.

    2005-01-01

    NASA remote sensing missions involving laser systems and their economic impact are outlined. Potential remote sensing missions include: green house gasses, tropospheric winds, ozone, water vapor, and ice cap thickness. Systems to perform these measurements use lanthanide series lasers and nonlinear devices including second harmonic generators and parametric oscillators. Demands these missions place on the laser and nonlinear optical materials are discussed from a materials point of view. Methods of designing new laser and nonlinear optical materials to meet these demands are presented.

  7. Measurement and Simulation of Thermal Conductivity of Hafnium-Aluminum Thermal Neutron Absorber Material

    NASA Astrophysics Data System (ADS)

    Guillen, Donna Post; Harris, William H.

    2016-09-01

    A metal matrix composite (MMC) material composed of hafnium aluminide (Al3Hf) intermetallic particles in an aluminum matrix has been identified as a promising material for fast flux irradiation testing applications. This material can filter thermal neutrons while simultaneously providing high rates of conductive cooling for experiment capsules. The purpose of this work is to investigate effects of Hf-Al material composition and neutron irradiation on thermophysical properties, which were measured before and after irradiation. When performing differential scanning calorimetry (DSC) on the irradiated specimens, a large exotherm corresponding to material annealment was observed. Therefore, a test procedure was developed to perform DSC and laser flash analysis (LFA) to obtain the specific heat and thermal diffusivity of pre- and post-annealment specimens. This paper presents the thermal properties for three states of the MMC material: (1) unirradiated, (2) as-irradiated, and (3) irradiated and annealed. Microstructure-property relationships were obtained for the thermal conductivity. These relationships are useful for designing components from this material to operate in irradiation environments. The ability of this material to effectively conduct heat as a function of temperature, volume fraction Al3Hf, radiation damage, and annealing is assessed using the MOOSE suite of computational tools.

  8. Mid- and far-infrared spectroscopy of ices - Optical constants and integrated absorbances

    NASA Technical Reports Server (NTRS)

    Hudgins, D. M.; Sandford, S. A.; Allamandola, L. J.; Tielens, A. G. G. M.

    1993-01-01

    Laboratory spectra through the mid-infrared (4000 to 500/cm (2.5-20 microns) have been used to calculate the optical constants (n and k) and integrated absorption coefficients (A) for a variety of pure and mixed molecular ices of relevance to astrophysics. The ices studied were H2O, CH3OH, CO2, OCS, CH4, CO2 + CH4, CO2 + OCS, CO + CH4, CO + OCS, O2 + CH4, O2 + OCS, N2 + CH4, N2 + OCS, H2O + CH4, H2O + OCS, and H2O + CH3OH + CO + NH3. In addition, the measurements have been extended through the far-infrared (500 to 50/cm (20-200 microns) for the H2O, CH3OH, and H2O + CH3OH + CO + NH3 ices.

  9. Optical and THz investigations of mid-IR materials exposed to alpha particle irradiation

    NASA Astrophysics Data System (ADS)

    Sporea, Dan; Mihai, Laura; Sporea, Adelina; Vâţã, Ion

    2017-01-01

    The paper is the first comprehensive study on alpha particle irradiation effects on four mid-IR materials: CaF2, BaF2, Al2O3 (sapphire) and ZnSe. The measurements of the optical spectral transmittance, spectral diffuse reflectance, radioluminescent emission, terahertz (THz) spectral response, transmittance, absorbance, refractive index, real and imaginary parts of the dielectric constant and THz imaging are used as complementary investigations to evaluate these effects. The simulations were run to estimate: (i) the penetration depth, (ii) the scattering of alpha particle beam, (iii) the amount of material affected by this interaction, and (iv) the number of vacancies produced by the radiation exposure for each type of material. The simulation results are compared to the off-line measurement outcomes. The delay and spectral composition change of the reflected THz signal highlight the modification induced in the tested materials by the irradiation process.

  10. Optical and THz investigations of mid-IR materials exposed to alpha particle irradiation

    PubMed Central

    Sporea, Dan; Mihai, Laura; Sporea, Adelina; Vâţã, Ion

    2017-01-01

    The paper is the first comprehensive study on alpha particle irradiation effects on four mid-IR materials: CaF2, BaF2, Al2O3 (sapphire) and ZnSe. The measurements of the optical spectral transmittance, spectral diffuse reflectance, radioluminescent emission, terahertz (THz) spectral response, transmittance, absorbance, refractive index, real and imaginary parts of the dielectric constant and THz imaging are used as complementary investigations to evaluate these effects. The simulations were run to estimate: (i) the penetration depth, (ii) the scattering of alpha particle beam, (iii) the amount of material affected by this interaction, and (iv) the number of vacancies produced by the radiation exposure for each type of material. The simulation results are compared to the off-line measurement outcomes. The delay and spectral composition change of the reflected THz signal highlight the modification induced in the tested materials by the irradiation process. PMID:28067289

  11. Laser diode structures with a saturable absorber for high-energy picosecond optical pulse generation by combined gain-and Q-switching

    NASA Astrophysics Data System (ADS)

    Ryvkin, B. S.; Avrutin, E. A.; Kostamovaara, J. E. K.; Kostamovaara, J. T.

    2017-02-01

    The performance of gain-switched Fabry-Perot asymmetric-waveguide semiconductor lasers with a large equivalent spot size and an intracavity saturable absorber was investigated experimentally and theoretically. The laser with a short (˜20 μm) absorber emitted high-energy afterpulse-free optical pulses in a broad range of injection current pulse amplitudes; optical pulses with a peak power of about 35 W and a duration of about 80 ps at half maximum were achieved with a current pulse with an amplitude of just 8 A and a duration of 1.5 ns. Good quality pulsations were observed in a broad range of elevated temperatures. The introduction of a substantially longer absorber section leads to strong spectral broadening of the output without a significant improvement to pulse energy and peak power.

  12. Numerical simulation of optical Stark effect saturable absorbers in mode-locked femtosecond VECSELs using a modified two-level atom model.

    PubMed

    Quarterman, A H; Carswell, S; Daniell, G J; Mihoubi, Z; Wilcox, K G; Chung, A L; Apostolopoulos, V; Tropper, A C

    2011-12-19

    The interaction of an optical pulse with a quantum well saturable absorber is simulated using a semi-classical two-level-atom model which has been modified to approximate spectral hole burning in the carrier distribution. Saturable absorption behaviour is examined in the limit where pulse duration approaches the carrier-carrier scattering time. For long pulses bleaching dominates the absorber response but as the pulse duration approaches the carrier-carrier scattering timescale an additional pulse shaping mechanism becomes active, allowing the absorber to continue to shorten pulses beyond the limit set by bleaching. Examination of the spectral and temporal absorption profiles suggests that intense pulses experience additional pulse shortening from the optical Stark effect.

  13. Use of Diamond as an Optical Material

    DTIC Science & Technology

    1991-09-27

    New polishing methods hpve yielded smooth surfaces in reasonable polishing times. Recent research hclds promise for large optics made from single... forced to the surface , precipitating on the surface as a diamond layer. A halogen-assisted CVD method has recently been discovered for producing...diamond [24]; however, this research is in an early stage and has not yet resulted in good quality diamond films. Optical Properties of CVD Diamond. Many

  14. Optimisation of the electromagnetic matching of manganese dioxide/multi-wall carbon nanotube composites as dielectric microwave-absorbing materials

    NASA Astrophysics Data System (ADS)

    Ting, Tzu-Hao; Chiang, Chih-Chia; Lin, Po-Chuan; Lin, Chia-Huei

    2013-08-01

    An optimised composite sample was prepared using two dielectric materials manganese dioxide (MnO2) and multi-wall carbon nanotubes (MWNTs) in an epoxy-resin matrix. Structural characterisations of both the synthesised manganese dioxide (MnO2) and the multi-wall carbon nanotubes (MWNTs) were performed by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The microwave absorption properties of dielectric composites with different weight fractions of MnO2 were investigated by measuring the complex permittivity, the complex permeability and the reflection loss in the 2-18 and 18-40 GHz microwave frequency ranges using the free space method. The complex permittivity varied with the MnO2 content, and the results show that a high concentration of fillers increased the dielectric constant. Therefore, the appropriate combination of components and experimental conditions can produce materials with specific characteristic for use as wide-band microwave absorbers.

  15. DURIP97 Instrumentation for Characterization of Two-Photon Absorbing Organic Materials

    DTIC Science & Technology

    2007-11-02

    Room Bl 15 Boiling AFB DC 20332- 8050 5 . FUNDING NUMBERS AFOSR Grant F49620-97-1-0200 8. PERFORMING ORGANIZATION REPORT NUMBER 11. SUPPLEMENTARY...REPORT 1 Final Technical ...u DATES CUVCHED 4/1/97 - 3/ 31 /98 4. TITLE AND SUBTITLE DURIP97 Instrumentation for Characterization of Two-Photon...in great demand for variety-of applications including, two-photon excited fluorescence microscopy (7- 4), optical limiting ( 5 - 7), three-dimensional

  16. Absorption-induced scattering and surface plasmon out-coupling from absorber-coated plasmonic metasurfaces

    PubMed Central

    Petoukhoff, Christopher E.; O'Carroll, Deirdre M.

    2015-01-01

    Interactions between absorbers and plasmonic metasurfaces can give rise to unique optical properties not present for either of the individual materials and can influence the performance of a host of optical sensing and thin-film optoelectronic applications. Here we identify three distinct mode types of absorber-coated plasmonic metasurfaces: localized and propagating surface plasmons and a previously unidentified optical mode type called absorption-induced scattering. The extinction of the latter mode type can be tuned by controlling the morphology of the absorber coating and the spectral overlap of the absorber with the plasmonic modes. Furthermore, we show that surface plasmons are backscattered when the crystallinity of the absorber is low but are absorbed for more crystalline absorber coatings. This work furthers our understanding of light–matter interactions between absorbers and surface plasmons to enable practical optoelectronic applications of metasurfaces. PMID:26271900

  17. Fabrication and comparison of thermochromic material-based fiber-optic sensors for monitoring the temperature of water

    NASA Astrophysics Data System (ADS)

    Yoo, Wook Jae; Seo, Jeong Ki; Jang, Kyoung Won; Heo, Ji Yeon; Moon, Jin Soo; Park, Jang-Yeon; Park, Byung Gi; Lee, Bongsoo

    2011-01-01

    In this study, we explored the feasibility of developing two types of fiber-optic temperature sensors that can measure the temperature of water. One uses a thermochromic material such as Lophine, whose optical absorbance changes according to the thermal variation. The other uses a thermochromic pigment that gradually loses its own color through heat absorption. We measured the change in the intensity of the reflected light, which was due to the variation of the optical property of Lophine and pigments, with thermal variation. The relationship between the temperature of water and the output signal of the fiber-optic sensors was also determined. The fiber-optic temperature sensor using Lophine provided a relatively broad range of temperature measurement with low sensitivity, whereas the fiber-optic temperature sensor using a thermochromic pigment offered a high sensitivity in a narrow range of temperature measurement.

  18. Electro-optic studies of novel organic materials and devices

    NASA Astrophysics Data System (ADS)

    Xu, Jianjun

    1997-11-01

    Specific single crystal organic materials have high potential for use in high speed optical signal processing and various other electro-optic applications. In this project some of the most important organic crystal materials were studied regarding their detailed electro- optic properties and potential device applications. In particular, the electro-optic properties of N-(4- Nitrophenyl)-L-Prolinol (NPP) and 4'-N,N- dimethylamino-4-methylstilbazolium tosylate (DAST) both of which have extremely large second order susceptibilites were studied. The orientation of the thin film crystal with respect to the substrate surface was determined using-X-ray diffraction. The principal axes of the single crystal thin film were determined by polarization transmission microscopy. The elements of the electro-optic coefficient tensor were measured by field induced birefringence measurements. Detailed measurements for NPP thin films with different orientations of the external electric field with respect to the charge transfer axis were carried out at a wavelength of 1064nm. The wavelength dependence of the electro-optic effect for DAST single crystal thin films was measured using a Ti:Sapphire laser. Several device geometries involving organic single crystal thin film materials were studied. A new method for the fabrication of channel waveguides for organic materials was initiated. Channel waveguides for NPP and ABP were obtained using this methods. Optical modulation due to the electro-optic effect based on the organic channel waveguide for NPP single crystal was demonstrated. The electro-optic modulation using NPP single crystals thin film in a Fabry-Perot cavity was measured. A device using a optical fiber half coupler and organic electro-optic thin film material was constructed, and it has potential applications in optical signal processing.

  19. 3D-Printing ‘Smarter’ Energy Absorbing Materials

    ScienceCinema

    Duoss, Eric

    2016-07-12

    Foams are, by nature, disordered materials studded with air pockets of varying sizes. Lack of control over the material’s architecture at the micrometer or nanometer scale can make it difficult to adjust the foam’s basic properties. But Eric Duoss and a team of Livermore researchers are using additive manufacturing to develop “smarter” silicone cushions. By architecting the structure at the micro scale, they are able to control macro-scale properties previously unachievable with foam materials.

  20. 2D Materials for Optical Modulation: Challenges and Opportunities.

    PubMed

    Yu, Shaoliang; Wu, Xiaoqin; Wang, Yipei; Guo, Xin; Tong, Limin

    2017-02-21

    Owing to their atomic layer thickness, strong light-material interaction, high nonlinearity, broadband optical response, fast relaxation, controllable optoelectronic properties, and high compatibility with other photonic structures, 2D materials, including graphene, transition metal dichalcogenides and black phosphorus, have been attracting increasing attention for photonic applications. By tuning the carrier density via electrical or optical means that modifies their physical properties (e.g., Fermi level or nonlinear absorption), optical response of the 2D materials can be instantly changed, making them versatile nanostructures for optical modulation. Here, up-to-date 2D material-based optical modulation in three categories is reviewed: free-space, fiber-based, and on-chip configurations. By analysing cons and pros of different modulation approaches from material and mechanism aspects, the challenges faced by using these materials for device applications are presented. In addition, thermal effects (e.g., laser induced damage) in 2D materials, which are critical to practical applications, are also discussed. Finally, the outlook for future opportunities of these 2D materials for optical modulation is given.

  1. Overlapping illusions by transformation optics without any negative refraction material

    NASA Astrophysics Data System (ADS)

    Sun, Fei; He, Sailing

    2016-01-01

    A novel method to achieve an overlapping illusion without any negative refraction index material is introduced with the help of the optic-null medium (ONM) designed by an extremely stretching spatial transformation. Unlike the previous methods to achieve such an optical illusion by transformation optics (TO), our method can achieve a power combination and reshape the radiation pattern at the same time. Unlike the overlapping illusion with some negative refraction index material, our method is not sensitive to the loss of the materials. Other advantages over existing methods are discussed. Numerical simulations are given to verify the performance of the proposed devices.

  2. UltraForm finishing process for optical materials

    NASA Astrophysics Data System (ADS)

    Fess, E.; Schoen, J.; Bechtold, M.; Mohring, D.; Bouvier, C.

    2005-09-01

    A new compliant sub-aperture optical finishing technique is being investigated for the removal of mid-spatial frequency artifacts and smoothing of hard polycrystalline infrared ceramics for aspheric applications and conformal shaped optics. The UltraForm concept was developed by OptiPro Systems, Ontario, NY, and is a joint process development effort with the Center for Optics Manufacturing (COM). The latest version of the UltraForm tool "V3" is of a belted design whereby a belt of finishing material is passed over a toroidal elastomeric wheel. Finishing materials used include a wide variety of pad materials and abrasive selections. Experimentation has been conducted using both slurry mixes and fixed abrasive bands. The toroidal wheel is rotated while the compliant tool is compressed into contact with the optical surface. Presented will be the current results in optical glasses and crystalline ceramics such as ALON, Spinel and Polycrystalline Alumina.

  3. Hydrogen Absorbing Materials for Use as Radiation Shielding During Extended Space Flight Missions

    NASA Technical Reports Server (NTRS)

    Grugel, Richard N.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    Minimizing radiation exposure from the galactic cosmic ray (GCR) environment during extended space missions is particularly crucial to crew health and safety. Here, an ideal candidate for shielding would be pure solid or liquid hydrogen, a material that effectively fragments heavy ions into ones of lower mass and energy that are more easily attenuated. Unfortunately, utilizing pure hydrogen is not presently feasible. It is, however, known that the hydrogen content of other materials (for example, metal hydrides, palladium alloys, and organic compounds) can exceed that of pure solid hydrogen and thus merit consideration as shielding candidates. This presentation will discuss an ongoing effort to develop novel shielding from such materials in concert with a coordinated testing/evaluation and modeling effort.

  4. Characterization of porous glass-ceramic material as absorber of electromagnetic radiation

    NASA Astrophysics Data System (ADS)

    Kazmina, O.; Suslyaev, V.; Dushkina, M.; Semukhin, B.

    2015-04-01

    Investigations of a foam glass-ceramic material synthesized from raw siliceous earth material by the two-stage method at temperatures below 950°C have demonstrated the improvement of its physic mechanical properties in comparison with foam glass synthesized from glass cullet. This material actively interacts with microwaves and can be used for the development of protective screens reducing the adverse effect of microwaves on biological objects, anechoic chambers, and rooms with low level of electromagnetic background noise. Spectra of the transmission and absorption coefficients and of the complex dielectric permittivity for frequencies in the range 26-260 GHz are presented. The observed effects demonstrate the existence of regions with partial and total reflection arising on the glass-pore boundary and of the microwave interaction with ultradisperse carbon particles that remain after foaming with incomplete frothier transition from the soot to the gas phase.

  5. Electromagnetic power absorber

    NASA Technical Reports Server (NTRS)

    Iwasaki, R. S. (Inventor)

    1979-01-01

    A structure is presented with a surface portion of dielectric material which passes electromagnetic radiation and with a portion below the surface which includes material that absorbs the radiation, the face of the structure being formed with numerous steep ridges. The steepness of the dielectric material results in a high proportion of the electromagnetic energy passing through the surface for absorption by the absorbing material under the surface. A backing of aluminum or other highly heat-conductive and reflective material lies under the face and has very steep protuberances supporting the absorbing and dielectric materials.

  6. Optical correlators with fast updating speed using photorefractive semiconductor materials

    NASA Technical Reports Server (NTRS)

    Gheen, Gregory; Cheng, Li-Jen

    1988-01-01

    The performance of an updatable optical correlator which uses a photorefractive semiconductor to generate real-time matched filters is discussed. The application of compound semiconductors makes possible high-speed operation and low optical input intensities. The Bragg diffraction is considered, along with the speed and power characteristics of these materials. Experimental results on photorefractive GaAs are presented.

  7. Determination of refractive index and absorbance modulation amplitudes from angular selectivity of holograms in polymer material with phenanthrenequinone

    NASA Astrophysics Data System (ADS)

    Borisov, Vladimir; Veniaminov, Andrey

    2015-10-01

    Amplitude and phase contributions to mixed volume holographic gratings were extracted from measured contours of angular selectivity. Holograms for the investigation were recorded in the glassy polymer material with phenan-threnequinone (PQ) using the DPSS CW laser (532 nm) and then self-developed due to molecular diffusion of PQ, reaching diffraction efficiency about 40%. Refractive index and absorbance modulation amplitudes of those holograms were obtained as adjustable parameters from theoretical equations by fitting angular dependencies of zeros and 1st orders diffraction efficiency measured at 450, 473, 532, and 633 nm at the different stages of hologram development. Mixed gratings manifest themselves in asymmetrical transmittance selectivity contours with one minimum and one maximum shifted with respect to the Bragg angle, while symmetrical contours with a minimum or a maximum at the Bragg angle are characteristic of pure phase and amplitude gratings, respectively. In the course of a hologram development, it converts from a predominantly amplitude-mixed to almost purely phase one in the case of readout using a light within the absorption band of PQ and maintains the phase nature besides it. The value of refractive index amplitude is ranging from 5×10-6 to 10-4 and the value of absorbance amplitude is up to 140 m-1.

  8. Optical properties of direct restorative materials

    SciTech Connect

    Miyagawa, Y.; Powers, J.M.; O'Brien, W.J.

    1981-05-01

    The contrast ratio, light reflectivity, scattering coefficient, and absorption coefficient of four composites and an unfilled resin were calculated algebraically from reflection spectrophotometric data using Kubelka's equations. The correlation coefficient between calculated and experimental values of contrast ratio was 0.9996. Values of infinite optical thickness ranged from 4.19 to 6.70 mm.

  9. Antimicrobial Formulations of Absorbable Bone Substitute Materials as Drug Carriers Based on Calcium Sulfate

    PubMed Central

    Obermeier, A.; Kiokekli, M.; Büchner, H.; Vogt, S.; Stemberger, A.; Burgkart, R.; Lucke, M.

    2016-01-01

    Substitution of bones is a well-established, necessary procedure to treat bone defects in trauma and orthopedic surgeries. For prevention or treatment of perioperative infection, the implantation of resorbable bone substitute materials carrying antibiotics is a necessary treatment. In this study, we investigated the newly formulated calcium-based resorbable bone substitute materials containing either gentamicin (CaSO4-G [Herafill-G]), vancomycin (CaSO4-V), or tobramycin (Osteoset). We characterized the released antibiotic concentration per unit. Bone substitute materials were implanted in bones of rabbits via a standardized surgical procedure. Clinical parameters and levels of the antibiotic-releasing materials in serum were determined. Local concentrations of antibiotics were measured using antimicrobial tests of bone tissue. Aminoglycoside release kinetics in vitro per square millimeter of bead surface showed the most prolonged release for gentamicin, followed by vancomycin and, with the fastest release, tobramycin. In vivo level in serum detected over 28 days was highest for gentamicin at 0.42 μg/ml, followed by vancomycin at 0.11 μg/ml and tobramycin at 0.04 μg/ml. The clinical parameters indicated high biocompatibility for materials used. None of the rabbits subjected to the procedure showed any adverse reaction. The highest availability of antibiotics at 14.8 μg/g on day 1 in the cortical tibia ex vivo was demonstrated for gentamicin, decreasing within 14 days. In the medulla, vancomycin showed a high level at 444 μg/g on day 1, decreasing continuously over 14 days, whereas gentamicin decreased faster within the initial 3 days. The compared antibiotic formulations varied significantly in release kinetics in serum as well as locally in medulla and cortex. PMID:27067337

  10. Spacecraft materials guide. [including: encapsulants and conformal coatings; optical materials; lubrication; and, bonding and joining processes

    NASA Technical Reports Server (NTRS)

    Staugaitis, C. L. (Editor)

    1975-01-01

    Materials which have demonstrated their suitability for space application are summarized. Common, recurring problems in encapsulants and conformal coatings, optical materials, lubrication, and bonding and joining are noted. The subjects discussed include: low density and syntactic foams, electrical encapsulants; optical glasses, interference filter, mirrors; oils, greases, lamillar lubricants; and, soldering and brazing processes.

  11. Carbon nanotube-based functional materials for optical limiting.

    PubMed

    Chen, Yu; Lin, Ying; Liu, Ying; Doyle, James; He, Nan; Zhuang, Xiaodong; Bai, Jinrui; Blau, Werner J

    2007-01-01

    Optical limiting is an important application of nonlinear optics, useful for the protection of human eyes, optical elements, and optical sensors from intense laser pulses. An optical limiter is such a device that strongly attenuates high intensity light and potentially damaging light such as focused laser beams, whilst allowing for the high transmission of ambient light. Optical limiting properties of carbon nanotube suspensions, solubilized carbon nanotubes, small molecules doped carbon nanotubes and polymer/carbon nanotube composites have been reviewed. The optical limiting responses of carbon nanotube suspensions are shown to be dominated by nonlinear scattering as a result of thermally induced solvent-bubble formation and sublimation of the nanotubes, while the solubilized carbon nanotubes optically limit through nonlinear absorption mechanism and exhibit significant solution-concentration-dependent optical limiting responses. In the former case the optical limiting results are independent of nanotube concentrations at the same linear transmittance as that of the solubilized systems. Many efforts have been invested into the research of polymer/carbon nanotube composites in an attempt to allow for the fabrication of films required for the use of nanotubes in a real optical limiting application. The higher carbon nanotube content samples block the incident light more effectively at higher incident energy densities or intensities. The optical limiting mechanism of these composite materials is quite complicated. Besides nonlinear scattering contribution to the optical limiting, there may also be other contributions e.g., nonlinear absorption, nonlinear refraction, electronic absorption and others to the optical limiting. Further improvements in the optical limiting efficiency of the composites and in the dispersion and alignment properties of carbon nanotubes in the polymer matrix could be realized by variation of both nanostructured guest and polymer host, and by

  12. 10B areal density: A novel approach for design and fabrication of B4C/6061Al neutron absorbing materials

    NASA Astrophysics Data System (ADS)

    Li, Yuli; Wang, Wenxian; Zhou, Jun; Chen, Hongsheng; Zhang, Peng

    2017-04-01

    In this paper, a novel approach to evaluate the neutron shielding performance of a boron-containing neutron absorbing material was proposed for the first time through the establishment of a direct relationship between 10B areal density (10BAD) of the material and its neutron absorption ratio. It is found when the 10BAD of a material is greater than 0.034 g/cm2, the material will achieve a good neutron shielding performance. Based on this proposed approach, B4C/6061Al composite plates with different B4C content (10 wt%, 20 wt%, 30 wt%) were successfully fabricated using vacuum hot pressing followed by hot-extrusion. The characteristics of the B4C/Al interface were studied in details using transmission electron microscopy (TEM), and the effects of B4C particle content on microstructure and mechanical properties of the Al matrix were investigated. Through current studies, B4C/6061Al composite plates possessing good neutron shielding performance and tensile strength are found to be able to be fabricated using either 20 wt% of B4C content with a plate thickness of 4.5 mm or 30 wt% B4C content with a plate thickness of 3 mm.

  13. A new optical method coupling light polarization and Vis-NIR spectroscopy to improve the measured absorbance signal's quality of soil samples.

    NASA Astrophysics Data System (ADS)

    Gobrecht, Alexia; Bendoula, Ryad; Roger, Jean-Michel; Bellon-Maurel, Véronique

    2014-05-01

    Visible - Near-infrared spectroscopy (Vis-NIRS) is now commonly used to measure different physical and chemical parameters of soils, including carbon content. However, prediction model accuracy is insufficient for Vis-NIRS to replace routine laboratory analysis. One of the biggest issues this technique is facing up to is light scattering due to soil particles. It causes departure in the assumed linear relationship between the Absorbance spectrum and the concentration of the chemicals of interest as stated by Beer-Lambert's Law, which underpins the calibration models. Therefore it becomes essential to improve the metrological quality of the measured signal in order to optimize calibration as light/matter interactions are at the basis of the resulting linear modeling. Optics can help to mitigate scattering effect on the signal. We put forward a new optical setup coupling linearly polarized light with a Vis-NIR spectrometer to free the measured spectra from multi-scattering effect. The corrected measured spectrum was then used to compute an Absorbance spectrum of the sample, using Dahm's Equation in the frame of the Representative Layer Theory. This method has been previously tested and validated on liquid (milk+ dye) and powdered (sand + dye) samples showing scattering (and absorbing) properties. The obtained Absorbance was a very good approximation of the Beer-Lambert's law absorbance. Here, we tested the method on a set of 54 soil samples to predict Soil Organic Carbon content. In order to assess the signal quality improvement by this method, we built and compared calibration models using Partial Least Square (PLS) algorithm. The prediction model built from new Absorbance spectrum outperformed the model built with the classical Absorbance traditionally obtained with Vis-NIR diffuse reflectance. This study is a good illustration of the high influence of signal quality on prediction model's performances.

  14. Balancing the energy budget of short-period giant planets: evidence for reflective clouds and optical absorbers

    NASA Astrophysics Data System (ADS)

    Schwartz, J. C.; Cowan, N. B.

    2015-06-01

    We consider 50 transiting short-period giant planets for which eclipse depths have been measured at multiple infrared wavelengths. The aggregate dayside emission spectrum of these planets exhibits no molecular features, nor is brightness temperature greater in the near-infrared. We combine brightness temperatures at various infrared wavelengths to estimate the dayside effective temperature of each planet. We find that dayside temperatures are proportional to irradiation temperatures, indicating modest Bond albedo and no internal energy sources. We place joint constraints on Bond albedo, AB, and day-to-night heat transport efficiency, ε, for six planets by combining thermal eclipse and phase variation measurements (HD 149026b, HD 189733b, HD 209458b, WASP-12b, WASP-18b, and WASP-43b). We confirm that planets with high irradiation temperatures have low heat transport and that WASP-43b has inexplicably poor transport; these results are statistically significant even if the precision of single-eclipse measurements has been overstated by a factor of 3. Lastly, we attempt to break the AB-ε degeneracy for nine planets with both thermal and optical eclipse observations, but no thermal phase measurements. We find a systematic offset between Bond albedos inferred from thermal phase variations (AB ≈ 0.35) and geometric albedos extracted from visible light measurements (Ag ≈ 0.1). These observations can be reconciled if most hot Jupiters have clouds that reflect 30-50 per cent of incident near-infrared radiation, and optical absorbers in the cloud particles or above the cloud deck.

  15. Analysis of SnS2 hyperdoped with V proposed as efficient absorber material.

    PubMed

    Seminovski, Yohanna; Palacios, Pablo; Wahnón, Perla

    2014-10-01

    Intermediate-band materials can improve the photovoltaic efficiency of solar cells through the absorption of two subband-gap photons that allow extra electron-hole pair formations. Previous theoretical and experimental findings support the proposal that the layered SnS2 compound, with a band-gap of around 2 eV, is a candidate for an intermediate-band material when it is doped with a specific transition-metal. In this work we characterize vanadium doped SnS2 using density functional theory at the dilution level experimentally found and including a dispersion correction combined with the site-occupancy-disorder method. In order to analyze the electronic characteristics that depend on geometry, two SnS2 polytypes partially substituted with vanadium in symmetry-adapted non-equivalent configurations were studied. In addition the magnetic configurations of vanadium in a SnS2 2H-polytype and its comparison with a 4H-polytype were also characterized. We demonstrate that a narrow intermediate-band is formed, when these dopant atoms are located in different layers. Our theoretical predictions confirm the recent experimental findings in which a paramagnetic intermediate-band material in a SnS2 2H-polytype with 10% vanadium concentration is obtained.

  16. Analysis of SnS2 hyperdoped with V proposed as efficient absorber material

    NASA Astrophysics Data System (ADS)

    Seminovski, Yohanna; Palacios, Pablo; Wahnón, Perla

    2014-10-01

    Intermediate-band materials can improve the photovoltaic efficiency of solar cells through the absorption of two subband-gap photons that allow extra electron-hole pair formations. Previous theoretical and experimental findings support the proposal that the layered SnS2 compound, with a band-gap of around 2 eV, is a candidate for an intermediate-band material when it is doped with a specific transition-metal. In this work we characterize vanadium doped SnS2 using density functional theory at the dilution level experimentally found and including a dispersion correction combined with the site-occupancy-disorder method. In order to analyze the electronic characteristics that depend on geometry, two SnS2 polytypes partially substituted with vanadium in symmetry-adapted non-equivalent configurations were studied. In addition the magnetic configurations of vanadium in a SnS2 2H-polytype and its comparison with a 4H-polytype were also characterized. We demonstrate that a narrow intermediate-band is formed, when these dopant atoms are located in different layers. Our theoretical predictions confirm the recent experimental findings in which a paramagnetic intermediate-band material in a SnS2 2H-polytype with 10% vanadium concentration is obtained.

  17. Dependence of microwave absorption properties on ferrite volume fraction in MnZn ferrite/rubber radar absorbing materials

    NASA Astrophysics Data System (ADS)

    Gama, Adriana M.; Rezende, Mirabel C.; Dantas, Christine C.

    2011-11-01

    We report the analysis of measurements of the complex magnetic permeability ( μr) and dielectric permittivity ( ɛr) spectra of a rubber radar absorbing material (RAM) with various MnZn ferrite volume fractions. The transmission/reflection measurements were carried out in a vector network analyzer. Optimum conditions for the maximum microwave absorption were determined by substituting the complex permeability and permittivity in the impedance matching equation. Both the MnZn ferrite content and the RAM thickness effects on the microwave absorption properties, in the frequency range of 2-18 GHz, were evaluated. The results show that the complex permeability and permittivity spectra of the RAM increase directly with the ferrite volume fraction. Reflection loss calculations by the impedance matching degree (reflection coefficient) show the dependence of this parameter on both thickness and composition of RAM.

  18. Optical band gap of NpO2 and PuO2 from optical absorbance of epitaxial films

    NASA Astrophysics Data System (ADS)

    Mark McCleskey, T.; Bauer, Eve; Jia, Quanxi; Burrell, Anthony K.; Scott, Brian L.; Conradson, Steven D.; Mueller, Alex; Roy, Lindsay; Wen, Xiaodong; Scuseria, Gustavo E.; Martin, Richard L.

    2013-01-01

    We report a solution based synthesis of epitaxial thin films of neptunium oxide and plutonium oxide. Actinides represent a challenge to first principle calculations due to features that arise from f orbital interactions. Conventional semi-local density functional theory predicts NpO2 and PuO2 to be metallic, when they are well known insulators. Improvements in theory are dependent on comparison with accurate measurements of material properties, which in turn demand high-quality samples. The high melting point of actinide oxides and their inherent radioactivity makes single crystal and epitaxial film formation challenging. We report on the preparation of high quality epitaxial actinide films. The films have been characterized through a combination of X-ray diffraction and X-ray absorption fine structure (XANES and EXAFS) measurements. We report band gaps of 2.80 ± 0.1 eV and 2.85 ± 0.1 eV at room temperature for PuO2 and NpO2, respectively, and compare our measurements with state-of-the-art calculations.

  19. Influence of optical material properties on the perception of liquids.

    PubMed

    van Assen, Jan Jaap R; Fleming, Roland W

    2016-12-01

    In everyday life we encounter a wide range of liquids (e.g., water, custard, toothpaste) with distinctive optical appearances and viscosities. Optical properties (e.g., color, translucency) are physically independent of viscosity, but, based on experience with real liquids, we may associate specific appearances (e.g., water, caramel) with certain viscosities. Conversely, the visual system may discount optical properties, enabling "viscosity constancy" based primarily on the liquid's shape and motion. We investigated whether optical characteristics affect the perception of viscosity and other properties of liquids. We simulated pouring liquids with viscosities ranging from water to molten glass and rendered them with nine different optical characteristics. In Experiment 1, observers (a) adjusted a match stimulus until it had the same perceived viscosity as a test stimulus with different optical properties, and (b) rated six physical properties of the test stimuli (runniness, shininess, sliminess, stickiness, warmth, wetness). We tested moving and static stimuli. In Experiment 2, observers had to associate names with every liquid in the stimulus set. We find that observers' viscosity matches correlated strongly with the true viscosities and that optical properties had almost no effect. However, some ratings of liquid properties did show substantial interactions between viscosity and optical properties. Observers associate liquid names primarily with optical cues, although some materials are associated with a specific viscosity or combination of viscosity and optics. These results suggest viscosity is inferred primarily from shape and motion cues but that optical characteristics influence recognition of specific liquids and inference of other physical properties.

  20. Scientists Identify New Family of Iron-Based Absorber Materials for Solar Cells (Fact Sheet), NREL Highlights, Science

    SciTech Connect

    Not Available

    2011-10-01

    Use of Earth-abundant materials in solar absorber films is critical for expanding the reach of photovoltaic (PV) technologies. The use of Earth-abundant and inexpensive Fe in PV was proposed more than 25 years ago in the form of FeS{sub 2} pyrite - fool's gold. Unfortunately, the material has been plagued by performance problems that to this day are both persistent and not well understood. Researchers from the National Renewable Energy Laboratory (NREL) and Oregon State University, working collaboratively in the Center for Inverse Design, an Energy Frontier Research Center, have uncovered several new insights into the problems of FeS{sub 2}. They have used these advances to propose and implement design rules that can be used to identify new Fe-containing materials that can circumvent the limitations of FeS{sub 2} pyrite. The team has identified that it is the unavoidable metallic secondary phases and surface defects coexisting near the FeS{sub 2} thin-film surfaces and grain boundaries that limit its open-circuit voltage, rather than the S vacancies in the bulk, which has long been commonly assumed. The materials Fe{sub 2}SiS{sub 4} and Fe{sub 2}GeS{sub 4} hold considerable promise as PV absorbers. The ternary Si compound is especially attractive, as it contains three of the more abundant low-cost elements available today. The band gap (E{sub g} = 1.5 eV) from both theory and experiment is higher than those of c-Si and FeS{sub 2}, offering better absorption of the solar spectrum and potentially higher solar cell efficiencies. More importantly, these materials do not have metallic secondary phase problems as seen in FeS{sub 2}. High calculated formation energies of donor-type defects are consistent with p-type carriers in thin films and are prospects for high open-circuit voltages in cells.

  1. New materials technology for latching electro-optic devices

    NASA Astrophysics Data System (ADS)

    Hood, Patrick J.; Mastrangelo, John C.; Chen, Shaw H.

    1999-04-01

    This paper presents the current status of a new class of liquid crystal material being developed for latching electrooptic applications. This new material has the unique property of being electrooptic and fully latching. That is, in one state, the material has the properties of a conventional liquid crystal, capable of being aligned with either an electric or magnetic field; in its other state, it is an optical quality solid that maintains the molecular alignment set while in the fluid state. Experiments have shown that current materials can be switched on the order of milliseconds, as is the case with conventional nematic liquid crystals. In the solid state, the electric field can be removed with no change to the previously set optical properties because the molecular alignment is frozen in place, which should last for an extended period of time. In addition, the material exhibits broad temperature stability in the solid state, enabling devices to be developed that operate from cryogenic temperatures to 80 degrees C without the use of a temperature controller. This new material is ideally suited for applications where the size and mechanical robustness of an electrooptic device is desired, along with the latching capability of optomechanical devices. This materials technology alone will currently not meet high-speed switch requirements. However, this technology can be integrated with other state-of-the-art high-speed materials to provide a high-speed latching device. Devices currently under investigation using this materials include optical switches, optical attenuators and tunable filters.

  2. Advances in nonlinear optical materials and devices

    NASA Technical Reports Server (NTRS)

    Byer, Robert L.

    1991-01-01

    The recent progress in the application of nonlinear techniques to extend the frequency of laser sources has come from the joint progress in laser sources and in nonlinear materials. A brief summary of the progress in diode pumped solid state lasers is followed by an overview of progress in nonlinear frequency extension by harmonic generation and parametric processes. Improved nonlinear materials including bulk crystals, quasiphasematched interactions, guided wave devices, and quantum well intersubband studies are discussed with the idea of identifying areas of future progress in nonlinear materials and devices.

  3. Traditional and emerging materials for optical metasurfaces

    NASA Astrophysics Data System (ADS)

    Zhu, Alexander Y.; Kuznetsov, Arseniy I.; Luk'yanchuk, Boris; Engheta, Nader; Genevet, Patrice

    2017-03-01

    One of the most promising and vibrant research areas in nanotechnology has been the field of metasurfaces. These are two dimensional representations of metaatoms, or artificial interfaces designed to possess specialized electromagnetic properties which do not occur in nature, for specific applications. In this article, we present a brief review of metasurfaces from a materials perspective, and examine how the choice of different materials impact functionalities ranging from operating bandwidth to efficiencies. We place particular emphasis on emerging and non-traditional materials for metasurfaces such as high index dielectrics, topological insulators and digital metamaterials, and the potentially transformative role they could play in shaping further advances in the field.

  4. Absorbed Gamma-Ray Doses due to Natural Radionuclides in Building Materials

    SciTech Connect

    Aguiar, Vitor A. P.; Medina, Nilberto H.; Moreira, Ramon H.; Silveira, Marcilei A. G.

    2010-05-21

    This work is devoted to the application of high-resolution gamma-ray spectrometry in the study of the effective dose coming from naturally occurring radionuclides, namely {sup 40}K, {sup 232}Th and {sup 238}U, present in building materials such as sand, cement, and granitic gravel. Four models were applied to estimate the effective dose and the hazard indices. The maximum estimated effective dose coming from the three reference rooms considered is 0.90(45) mSv/yr, and maximum internal hazard index is 0.77(24), both for the compact clay brick reference room. The principal gamma radiation sources are cement, sand and bricks.

  5. Dependence of the absorption of pulsed CO2-laser radiation by silane on wavenumber, fluence, pulse duration, temperature, optical path length, and pressure of absorbing and nonabsorbing gases

    NASA Astrophysics Data System (ADS)

    Bl/aŻejowski, Jerzy; Gruzdiewa, Ludwika; Rulewski, Jacek; Lampe, Frederick W.

    1995-05-01

    The absorption of three lines [P(20), 944.2 cm-1; P(14), 949.2 cm-1; and R(24), 978.5 cm-1] of the pulsed CO2 laser (0001-1000 transition) by SiH4 was measured at various pulse energy, pulse duration, temperature, optical path length, and pressure of the compound and nonabsorbing foreign gases. In addition, low intensity infrared absorption spectrum of silane was compared with high intensity absorption characteristics for all lines of the pulsed CO2 laser. The experimental dependencies show deviations from the phenomenological Beer-Lambert law which can be considered as arising from the high intensity of an incident radiation and collisions of absorbing molecules with surroundings. These effects were included into the expression, being an extended form of the Beer-Lambert law, which reasonably approximates all experimental data. The results, except for extending knowledge on the interaction of a high power laser radiation with matter, can help understanding and planning processes leading to preparation of silicon-containing technologically important materials.

  6. Tunable microwave absorbing nano-material for X-band applications

    NASA Astrophysics Data System (ADS)

    Sadiq, Imran; Naseem, Shahzad; Ashiq, Muhammad Naeem; Khan, M. A.; Niaz, Shanawer; Rana, M. U.

    2016-03-01

    The effect of rare earth elements substitution in Sr1.96RE0.04Co2Fe27.80Mn0.2O46 (RE=Ce, Gd, Nd, La and Sm) X-type hexagonal ferrites prepared by using sol gel autocombustion method was studied. The XRD and FTIR analysis show the single phase of the prepared material. The lattice constants a (Å) and c (Å) varies with the additives. The particle size measured by Scherer formula for all the samples varies in the range of 54-100 nm and confirmed by the TEM analysis. The average grain size measured by SEM analysis lies in the range of 0.672-1.01 μm for all the samples. The Gd-substituted ferrite has higher value of coercivity (526.06 G) among all the samples which could be a good material for longitudinal recording media. The results also indicate that the Gd-substituted sample has maximum reflection loss of -25.2 dB at 11.878 GHz, can exhibit the best microwave absorption properties among all the substituted samples. Furthermore, the minimum value of reflection loss shifts towards the lower and higher frequencies with the substitution of rare earth elements which confirms that the microwave absorption properties can be tuned with the substitution of rare earth elements in pure ferrites. The peak value of attenuation constant at higher frequency agrees well the reflection loss data.

  7. A Versatile and Scalable Approach toward Robust Superhydrophobic Porous Materials with Excellent Absorbency and Flame Retardancy

    NASA Astrophysics Data System (ADS)

    Ruan, Changping; Shen, Mengxia; Ren, Xiaoyan; Ai, Kelong; Lu, Lehui

    2016-08-01

    The frequent oil spillages and the industrial discharge of organic contaminants have not only created severe environmental and ecological crises, but also cause a risk of fire and explosion. These environmental and safety issues emphasize the urgent need for materials that possess superior sorption capability and less flammability and thus can effectively and safely clean up the floating oils and water-insoluble organic compounds. Here we present the successful hydrophobic modification of the flame retardant melamine sponge with a commercial fluorosilicone, by using a facile one-step solvent-free approach and demonstrate that the resultant superhydrophobic sponge not only exhibits extraordinary absorption efficiency (including high capacity, superior selectivity, good recyclability, and simple recycling routes), but also retains excellent flame retardancy and robust stability. In comparison to conventional methods, which usually utilize massive organic solvents, the present approach does not involve any complicated process or sophisticated equipment nor generates any waste liquids, and thus is a more labor-saving, environment-friendly, energy-efficient and cost-effective strategy for the hydrophobic modification. Taking into account the critical role of hydrophobic porous materials, especially in the field of environmental remediation, the approach presented herein would be highly valuable for environmental remediation and industrial applications.

  8. A Versatile and Scalable Approach toward Robust Superhydrophobic Porous Materials with Excellent Absorbency and Flame Retardancy.

    PubMed

    Ruan, Changping; Shen, Mengxia; Ren, Xiaoyan; Ai, Kelong; Lu, Lehui

    2016-08-09

    The frequent oil spillages and the industrial discharge of organic contaminants have not only created severe environmental and ecological crises, but also cause a risk of fire and explosion. These environmental and safety issues emphasize the urgent need for materials that possess superior sorption capability and less flammability and thus can effectively and safely clean up the floating oils and water-insoluble organic compounds. Here we present the successful hydrophobic modification of the flame retardant melamine sponge with a commercial fluorosilicone, by using a facile one-step solvent-free approach and demonstrate that the resultant superhydrophobic sponge not only exhibits extraordinary absorption efficiency (including high capacity, superior selectivity, good recyclability, and simple recycling routes), but also retains excellent flame retardancy and robust stability. In comparison to conventional methods, which usually utilize massive organic solvents, the present approach does not involve any complicated process or sophisticated equipment nor generates any waste liquids, and thus is a more labor-saving, environment-friendly, energy-efficient and cost-effective strategy for the hydrophobic modification. Taking into account the critical role of hydrophobic porous materials, especially in the field of environmental remediation, the approach presented herein would be highly valuable for environmental remediation and industrial applications.

  9. A Versatile and Scalable Approach toward Robust Superhydrophobic Porous Materials with Excellent Absorbency and Flame Retardancy

    PubMed Central

    Ruan, Changping; Shen, Mengxia; Ren, Xiaoyan; Ai, Kelong; Lu, Lehui

    2016-01-01

    The frequent oil spillages and the industrial discharge of organic contaminants have not only created severe environmental and ecological crises, but also cause a risk of fire and explosion. These environmental and safety issues emphasize the urgent need for materials that possess superior sorption capability and less flammability and thus can effectively and safely clean up the floating oils and water-insoluble organic compounds. Here we present the successful hydrophobic modification of the flame retardant melamine sponge with a commercial fluorosilicone, by using a facile one-step solvent-free approach and demonstrate that the resultant superhydrophobic sponge not only exhibits extraordinary absorption efficiency (including high capacity, superior selectivity, good recyclability, and simple recycling routes), but also retains excellent flame retardancy and robust stability. In comparison to conventional methods, which usually utilize massive organic solvents, the present approach does not involve any complicated process or sophisticated equipment nor generates any waste liquids, and thus is a more labor-saving, environment-friendly, energy-efficient and cost-effective strategy for the hydrophobic modification. Taking into account the critical role of hydrophobic porous materials, especially in the field of environmental remediation, the approach presented herein would be highly valuable for environmental remediation and industrial applications. PMID:27501762

  10. The search for very low loss fiber-optic materials

    NASA Astrophysics Data System (ADS)

    Lines, M. E.

    1984-11-01

    The materials, performance characteristics, and applications of optic fibers for telecommunications are discussed. Optic fibers can support 100 trillion cycles/sec carrier frequencies, have low loss characteristics, are not affected by stray electric fields, and are very thin. Carrier wave amplification is, however, necessary every 30-50 km for the state-of-the-art silica fibers. The invention of the laser in 1960 spurred the search for visible dielectric light carriers. High-quality silica fibers were produced by 1979 and opened the way for commercial telecommunications projects at loss rates of 0.2 dB/km. Signal attenuation due to fiber material properties has been attributed to Urbach, Rayleigh, and multiphonon sources. Multicomponent halide glasses are being investigated as better optic fiber materials due to theoretical loss limits of 0.01-0.0001 dB/km, which would permit transoceanic fiber optics links.

  11. Optical Fibre Sensors Using Graphene-Based Materials: A Review

    PubMed Central

    Hernaez, Miguel; Zamarreño, Carlos R.; Melendi-Espina, Sonia; Bird, Liam R.; Mayes, Andrew G.; Arregui, Francisco J.

    2017-01-01

    Graphene and its derivatives have become the most explored materials since Novoselov and Geim (Nobel Prize winners for Physics in 2010) achieved its isolation in 2004. The exceptional properties of graphene have attracted the attention of the scientific community from different research fields, generating high impact not only in scientific journals, but also in general-interest newspapers. Optical fibre sensing is one of the many fields that can benefit from the use of these new materials, combining the amazing morphological, chemical, optical and electrical features of graphene with the advantages that optical fibre offers over other sensing strategies. In this document, a review of the current state of the art for optical fibre sensors based on graphene materials is presented. PMID:28098825

  12. Advances in Anisotropic Materials for Optical Switching

    DTIC Science & Technology

    2010-09-16

    large change in the effective refractive index of the material , comparable to that obtained at transformation of a liquid into vapor. Liquid...crystall ine materials (LCs), both low·molecular weight as well as polymeric, make feasible such large changes of effective refractive index without a...frequencies and thus are uniqucly suitable for designing opt ical struc tures that maXimize the effect of changing birefringence/orientation on

  13. Laser Induced Damage in Optical Materials: 1980.

    DTIC Science & Technology

    1981-10-01

    alloy formation and diffusion normalization of sensitized stainless steel of antimony in aluminum ,Nucl. Instrum. Methods by laser surface melting, J... properties of materials needed by industry, commerce, educational institutions, and Government: provides advisory and research services to other...129 N.C. Fernelius, D.V. Dempsey, D.A. Walsh, D.B. O’Quinn and W.L. Knecht Material Property Requirements for Laser

  14. Photonic materials, structures and devices for Reststrahlen optics.

    PubMed

    Feng, K; Streyer, W; Zhong, Y; Hoffman, A J; Wasserman, D

    2015-11-30

    We present a review of existing and potential next-generation far-infrared (20-60 μm) optical materials and devices. The far-infrared is currently one of the few remaining frontiers on the optical spectrum, a space underdeveloped and lacking in many of the optical and optoelectronic materials and devices taken for granted in other, more technologically mature wavelength ranges. The challenges associated with developing optical materials, structures, and devices at these wavelengths are in part a result of the strong phonon absorption in the Reststrahlen bands of III-V semiconductors that collectively span the far-infrared. More than just an underexplored spectral band, the far-IR may also be of potential importance for a range of sensing applications in astrochemistry, biology, and industrial and geological processes. Additionally, with a suitable far-IR optical infrastructure, it is conceivable that even more applications could emerge. In this review, we will present recent progress on far-infrared materials and phenomena such as phononic surface modes, engineered composite materials, and optoelectronic devices that have the potential to serve as the next generation of components in a far-infrared optical tool-kit.

  15. Preparation and low-frequency microwave-absorbing properties of MWCNTs/Co-Ni/Fe3O4 hybrid material

    NASA Astrophysics Data System (ADS)

    Lu, Shao-Wei; Yuan, Chao-Jun; Jia, Cai-Xia; Ma, Ke-Ming; Wang, Xiao-Qiang

    2016-04-01

    MWCNTs/Co-Ni/Fe3O4 hybrid material has been successfully prepared by electroless plating and coprecipitation method, which is applied to the low-frequency microwave absorption. Their surface morphology, structure, magnetism and electromagnetic properties in the low-frequency range of 1-4GHz were characterized by field-emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and vector network analyzer. Results indicated that magnetic Co-Ni/Fe3O4 particles were attached on the surface of multi-walled carbon nanotubes successfully. The saturation magnetization of MWCNTs/Co-Ni/Fe3O4 hybrid materials was 68.6emu/g and the coercivity is 17.9 Oe. The electromagnetic and microwave absorbing properties analysis in the low-frequency range of 1-4GHz indicated that the hybrid material exhibited excellent magnetic loss and the maximum reflection loss could reach -13.57dB at 1.51GHz with 1.05GHz bandwidth below -5dB.

  16. Surface Modification of Fuel Cladding Materials with Integral Fuel BUrnable Absorber Boron

    SciTech Connect

    Dr. Kumar Sridharan; Dr. Todd Allen; Jesse Gudmundson; Benjamin Maier

    2008-11-03

    Integral fuel burnable absorgers (IFBA) are added to some rods in the fuel assembly to counteract excessive reactivity. These IFBA elements (usually boron or gadolinium) are presently incorporated in the U)2 pellets either by mixing in the pellets or as coatings on the pellet surface. In either case, the incorporation of ifba into the fuel has to be performed in a nuclear-regulated facility that is physically separated from the main plant. These operations tend to be costly and can add from 20 to 30% to the manufacturing cost of the fuel. The goal of this NEER research project was to develop an alternative approach that involves incorporation of IFBA element boron at the surface of the fuel cladding material.

  17. Integrated optical tamper sensor with planar waveguide

    DOEpatents

    Carson, R.F.; Casalnuovo, S.A.

    1993-01-05

    A monolithic optical tamper sensor, comprising an optical emitter and detector, connected by an optical waveguide and placed into the critical entry plane of an enclosed sensitive region, the tamper sensor having a myriad of scraps of a material optically absorbent at the wavelength of interest, such that when the absorbent material is in place on the waveguide, an unique optical signature can be recorded, but when entry is attempted into the enclosed sensitive region, the scraps of absorbent material will be displaced and the optical/electrical signature of the tamper sensor will change and that change can be recorded.

  18. Integrated optical tamper sensor with planar waveguide

    DOEpatents

    Carson, Richard F.; Casalnuovo, Stephen A.

    1993-01-01

    A monolithic optical tamper sensor, comprising an optical emitter and detector, connected by an optical waveguide and placed into the critical entry plane of an enclosed sensitive region, the tamper sensor having a myriad of scraps of a material optically absorbent at the wavelength of interest, such that when the absorbent material is in place on the waveguide, an unique optical signature can be recorded, but when entry is attempted into the enclosed sensitive region, the scraps of absorbent material will be displaced and the optical/electrical signature of the tamper sensor will change and that change can be recorded.

  19. Optical materials for space based laser systems

    NASA Technical Reports Server (NTRS)

    Buoncristiani, A. M.; Armagan, G.; Byvik, C. E.; Albin, S.

    1989-01-01

    The design features and performance characteristics of a sensitized holmium laser applicable to differential lidar and Doppler windshear measurements are presented, giving attention to the optimal choice of sensitizing/activating dopant ions. This development of a 2-micron region eye-safe laser, where holmium is sensitized by either hulium or erbium, has called for interionic energy transfer processes whose rate will not result in gain-switched pulses that are excessively long for atmospheric lidar and Doppler windshear detection. The application of diamond films for optical component hardening is noted.

  20. Experimental study of optical storage characteristics of photochromic material: pyrrylfulgide

    NASA Astrophysics Data System (ADS)

    Lei, Ming; Yao, Baoli; Chen, Yi; Han, Yong; Wang, Congmin; Wang, Yingli; Menke, Neimule; Chen, Guofu; Fan, Meigong

    2003-04-01

    Optical data storage is a frontier in the information science. Currently, there are mainly two kinds of storage materials, i.e., thermal-optic and photonic materials. The storage methods are divided into serial and parallel modes. In the market, the mature technique is CD-RW, which uses the thermal-optic material and serial method. The storage density of the CD-RW is restricted by the size of material particles, the conduction of heat, etc. Besides, the recording speed is seriously limited by the process of heating. Photonic materials and parallel method will be the trend in the optical data storage. Because it is based on the photon reaction on the molecule scale, the storage density and speed will be greatly increased. In this paper, a new kind of organic photochromic material -- pyrrylfulgide was studied. A parallel optical data storage system was established. Using the pyrrylfulgide/PMMA film as a recording medium, micro-images and binary digital information could be recorded, readout and erased in this parallel system. The recorded information on the film can be kept for at least 8 months in dark at room temperature. So far, the storage density is 3 x 107 bit/cm2.

  1. Numerical model for thermal parameters in optical materials

    NASA Astrophysics Data System (ADS)

    Sato, Yoichi; Taira, Takunori

    2016-04-01

    Thermal parameters of optical materials, such as thermal conductivity, thermal expansion, temperature coefficient of refractive index play a decisive role for the thermal design inside laser cavities. Therefore, numerical value of them with temperature dependence is quite important in order to develop the high intense laser oscillator in which optical materials generate excessive heat across mode volumes both of lasing output and optical pumping. We already proposed a novel model of thermal conductivity in various optical materials. Thermal conductivity is a product of isovolumic specific heat and thermal diffusivity, and independent modeling of these two figures should be required from the viewpoint of a clarification of physical meaning. Our numerical model for thermal conductivity requires one material parameter for specific heat and two parameters for thermal diffusivity in the calculation of each optical material. In this work we report thermal conductivities of various optical materials as Y3Al5O12 (YAG), YVO4 (YVO), GdVO4 (GVO), stoichiometric and congruent LiTaO3, synthetic quartz, YAG ceramics and Y2O3 ceramics. The dependence on Nd3+-doping in laser gain media in YAG, YVO and GVO is also studied. This dependence can be described by only additional three parameters. Temperature dependence of thermal expansion and temperature coefficient of refractive index for YAG, YVO, and GVO: these are also included in this work for convenience. We think our numerical model is quite useful for not only thermal analysis in laser cavities or optical waveguides but also the evaluation of physical properties in various transparent materials.

  2. [Using UV-Vis Absorbance for Characterization of Maturity in Composting Process with Different Materials].

    PubMed

    Zhao, Yue; Wei, Yu-quan; Li, Yang; Xi, Bei-dou; Wei, Zi-min; Wang, Xing-lei; Zhao, Zhi-nan; Ding, Jei

    2015-04-01

    The present study was conducted to assess the degree of humification in DOM during composting using different raw materials, and their effect on maturity of compost based on UV-Vis spectra measurements and chemometrics method. The raw materials of composting studied included chicken manure, pig manure, kitchen waste, lawn waste, fruits and vegetables waste, straw waste, green waste, sludge, and municipal solid waste. During composting, the parameters of UV-Vis spectra of DOM, including SUVA254 , SUVA280 , E250/E365, E4/E6, E2/E4, E2/E6, E253/E203, E253/E220, A226-400, S275-295 and S350-400 were calculated, Statistical analysis indicated that all the parameter were significantly changed during composting. SUVA254 and SUVA280 of DOM were continuously increased, E250/E365 and E4/E6 were continuously decreased in DOM, while A226-400, S275-295 and S350-400 of DOM at the final stage were significantly different with those at other stages of composting. Correlation analysis indicated that the parameters were significantly correlated with each other except for E2/E4 and E235/E203. Furthermore, principal component analysis suggested that A226-400, SUVA254, S350-400, SUVA280 and S275~295 were reasonable parameters for assessing the compost maturity. To distinguish maturity degree among different composts, hierarchical cluster analysis, an integrated tool utilizing multiple UV-Vis parameters, was performed based on the data (A226-400, SUVA254, S350-400, SUVA280 and S275-295) of DOM derived from the final stage of composting. Composts from different sources were clustered into 2 groups. The first group included chicken manure, pig manure, lawn waste, fruits and vegetables waste, green waste, sludge, and municipal solid waste characterized by a lower maturity degree, and the second group contained straw waste and kitchen waste associated with a higher maturity degree. The above results suggest that a multi-index of UV-Vis spectra could accurately evaluate the compost maturity

  3. Materials design using correlated oxides: Optical properties of vanadium dioxide

    NASA Astrophysics Data System (ADS)

    Tomczak, J. M.; Biermann, S.

    2009-05-01

    Materials with strong electronic Coulomb interactions play an increasing role in modern materials applications. "Thermochromic" systems, that exhibit thermally induced changes in their optical response, provide a particularly interesting case. The optical switching associated with the metal-insulator transition of vanadium dioxide (VO2), for example, has been proposed for use in "intelligent" windows that selectively filter radiative heat in hot weather conditions. In this work, we develop the theoretical tools for describing such a behaviour. Using a novel scheme for the calculation of the optical conductivity of correlated materials, we obtain quantitative agreement with experiments for both phases of VO2. On the example of an optimized energy-saving window setup, we further demonstrate that theoretical materials design has now come into reach, even for the particularly challenging class of correlated electron systems.

  4. Predicting and Designing Optical Properties of Inorganic Materials

    NASA Astrophysics Data System (ADS)

    Rondinelli, James M.; Kioupakis, Emmanouil

    2015-07-01

    Modern first-principles calculations based on density functional theory and related techniques enable the predictive modeling of the linear and nonlinear optical properties of materials without adjustable or empirical parameters. Today, atomistic calculations are an indispensable tool by which to understand the interrelationship between the underlying structure and the measured optical properties and are particularly suited for the design of new materials with desirable optical responses and performance. In this article, we discuss the first-principles design methodology, and we review recent results from the literature that exemplify the predictive power of the method for numerous inorganic materials and nanostructures. We also discuss topics of active research and future opportunities that will enable the wider adoption of atomistic simulation techniques for predictive materials design.

  5. Organic materials with nonlinear optical properties

    DOEpatents

    Stupp, Samuel I.; Son, Sehwan; Lin, Hong-Cheu

    1995-01-01

    The present invention is directed to organic materials that have the ability to double or triple the frequency of light that is directed through the materials. Particularly, the present invention is directed to the compound 4-[4-(2R)-2-cyano-7-(4'-pentyloxy-4-biphenylcarbonyloxy)phenylheptylidene) phenylcarbonyloxy]benzaldehyde, which can double the frequency of light that is directed through the compound. The invention is also directed to the compound (12-hydroxy-5,7-dodecadiynyl) 4'-[(4'-pentyloxy-4-biphenyl)carbonyloxy]-4-biphenylcarboxylate, and its polymeric form. The polymeric form can triple the frequency of light directed through it.

  6. Organic materials with nonlinear optical properties

    DOEpatents

    Stupp, S.I.; Son, S.; Lin, H.C.

    1995-05-02

    The present invention is directed to organic materials that have the ability to double or triple the frequency of light that is directed through the materials. Particularly, the present invention is directed to the compound 4-[4-(2R)-2-cyano-7-(4{prime}-pentyloxy-4-biphenylcarbonyloxy)phenylheptylidenephenylcarbonyloxy]benzaldehyde, which can double the frequency of light that is directed through the compound. The invention is also directed to the compound (12-hydroxy-5,7-dodecadiynyl)-4{prime}-[(4{prime}-pentyloxy-4-biphenyl)carbonyloxy]-4-biphenylcarboxylate, and its polymeric form. The polymeric form can triple the frequency of light directed through it. 4 figs.

  7. Bottom-up approach for microstructure optimization of sound absorbing materials.

    PubMed

    Perrot, Camille; Chevillotte, Fabien; Panneton, Raymond

    2008-08-01

    Results from a numerical study examining micro-/macrorelations linking local geometry parameters to sound absorption properties are presented. For a hexagonal structure of solid fibers, the porosity phi, the thermal characteristic length Lambda('), the static viscous permeability k(0), the tortuosity alpha(infinity), the viscous characteristic length Lambda, and the sound absorption coefficient are computed. Numerical solutions of the steady Stokes and electrical equations are employed to provide k(0), alpha(infinity), and Lambda. Hybrid estimates based on direct numerical evaluation of phi, Lambda('), k(0), alpha(infinity), Lambda, and the analytical model derived by Johnson, Allard, and Champoux are used to relate varying (i) throat size, (ii) pore size, and (iii) fibers' cross-section shapes to the sound absorption spectrum. The result of this paper tends to demonstrate the important effect of throat size in the sound absorption level, cell size in the sound absorption frequency selectivity, and fibers' cross-section shape in the porous material weight reduction. In a hexagonal porous structure with solid fibers, the sound absorption level will tend to be maximized with a 48+/-10 microm throat size corresponding to an intermediate resistivity, a 13+/-8 microm fiber radius associated with relatively small interfiber distances, and convex triangular cross-section shape fibers allowing weight reduction.

  8. Study of Photochromic Materials for Use in Optical Signal Processing.

    DTIC Science & Technology

    1987-11-01

    LDFP 07 C6 11. TITLE (kIclude Security Classification) STUDY OF PHOTOCHROMIC MATERIALS FOR USE IN OPZfCAL SIGNAL PROCESSING 12. PERSONAL AUTHOR(S) Dr...the feasibility of using photochromic materials for programmable spatial filters and optical data storage/ applications. Write and erase times...Mercuay Dithizonate 35 V. General Experimental Behavior of Photochromic Materials 39 VI. Kinetics of the Relaxation Reaction 44 VII. Dependence of the

  9. Cooperative enhancement of the nonlinear optical response in conjugated energetic materials: A TD-DFT study.

    PubMed

    Sifain, Andrew E; Tadesse, Loza F; Bjorgaard, Josiah A; Chavez, David E; Prezhdo, Oleg V; Scharff, R Jason; Tretiak, Sergei

    2017-03-21

    Conjugated energetic molecules (CEMs) are a class of explosives with high nitrogen content that posses both enhanced safety and energetic performance properties and are ideal for direct optical initiation. As isolated molecules, they absorb within the range of conventional lasers. Crystalline CEMs are used in practice, however, and their properties can differ due to intermolecular interaction. Herein, time-dependent density functional theory was used to investigate one-photon absorption (OPA) and two-photon absorption (TPA) of monomers and dimers obtained from experimentally determined crystal structures of CEMs. OPA scales linearly with the number of chromophore units, while TPA scales nonlinearly, where a more than 3-fold enhancement in peak intensity, per chromophore unit, is calculated. Cooperative enhancement depends on electronic delocalization spanning both chromophore units. An increase in sensitivity to nonlinear laser initiation makes these materials suitable for practical use. This is the first study predicting a cooperative enhancement of the nonlinear optical response in energetic materials composed of relatively small molecules. The proposed model quantum chemistry is validated by comparison to crystal structure geometries and the optical absorption of these materials dissolved in solution.

  10. Cooperative enhancement of the nonlinear optical response in conjugated energetic materials: A TD-DFT study

    NASA Astrophysics Data System (ADS)

    Sifain, Andrew E.; Tadesse, Loza F.; Bjorgaard, Josiah A.; Chavez, David E.; Prezhdo, Oleg V.; Scharff, R. Jason; Tretiak, Sergei

    2017-03-01

    Conjugated energetic molecules (CEMs) are a class of explosives with high nitrogen content that posses both enhanced safety and energetic performance properties and are ideal for direct optical initiation. As isolated molecules, they absorb within the range of conventional lasers. Crystalline CEMs are used in practice, however, and their properties can differ due to intermolecular interaction. Herein, time-dependent density functional theory was used to investigate one-photon absorption (OPA) and two-photon absorption (TPA) of monomers and dimers obtained from experimentally determined crystal structures of CEMs. OPA scales linearly with the number of chromophore units, while TPA scales nonlinearly, where a more than 3-fold enhancement in peak intensity, per chromophore unit, is calculated. Cooperative enhancement depends on electronic delocalization spanning both chromophore units. An increase in sensitivity to nonlinear laser initiation makes these materials suitable for practical use. This is the first study predicting a cooperative enhancement of the nonlinear optical response in energetic materials composed of relatively small molecules. The proposed model quantum chemistry is validated by comparison to crystal structure geometries and the optical absorption of these materials dissolved in solution.

  11. Optimization of doubly Q-switched lasers with both an acousto-optic modulator and a GaAs saturable absorber.

    PubMed

    Li, Dechun; Zhao, Shengzhi; Li, Guiqiu; Yang, Kejian

    2007-08-20

    A doubly Q-switched laser with both an acousto-optic (AO) modulator and a GaAs saturable absorber can obtain a more symmetric and shorter pulse with high pulse peak power, which has been experimentally proved. The key parameters of an optimally coupled doubly Q-switched laser with both an AO modulator and a GaAs saturable absorber are determined, and a group of general curves are generated for what we believe is the first time, when the single-photon absorption (SPA) and two-photon absorption (TPA) processes of GaAs are combined, and the Gaussian spatial distributions of the intracavity photon density and the initial population-inversion density as well as the influence of the AO Q-switch are considered. These key parameters include the optimal normalized coupling parameter, the optimal normalized GaAs saturable absorber parameters, and the normalized parameters of the AO Q-switch, which can maximize the output energy. Meanwhile, the corresponding normalized energy, the normalized peak power, and the normalized pulse width are given. The curves clearly show the dependence of the optimal key parameters on the parameters of the gain medium, the GaAs saturable absorber, the AO Q-switch, and the resonator. Sample calculations for a diode-pumped Nd3+:YVO4 laser with both an AO modulator and a GaAs saturable absorber are presented to demonstrate the use of the curves and the relevant formulas.

  12. Optical properties of nanostructured materials: a review

    NASA Astrophysics Data System (ADS)

    Flory, François; Escoubas, Ludovic; Berginc, Gérard

    2011-01-01

    Depending on the size of the smallest feature, the interaction of light with structured materials can be very different. This fundamental problem is treated by different theories. If first order theories are sufficient to describe the scattering from low roughness surfaces, second order or even higher order theories must be used for high roughness surfaces. Random surface structures can then be designed to distribute the light in different propagation directions. For complex structures such as black silicon, which reflects very little light, the theory needs further development. When the material is periodically structured, we speak about photonic crystals or metamaterials. Different theoretical approaches have been developed and experimental techniques are rapidly progressing. However, some work still remains to understand the full potential of this field. When the material is structured in dimension much smaller than the wavelength, the notion of complex refractive index must be revisited. Plasmon resonance can be excited by a progressing wave on metallic nanoparticles inducing a shaping of the absorption band and of the dispersion of the extinction coefficient. This addresses the problem of the permittivity of such metallic nanoparticles. The coupling between several metallic nanoparticles induces a field enhancement in the surrounding media, which can increase phenomena like scattering, absorption, luminescence, or Raman scattering. For semiconductor nanoparticles, electron confinement also induces a modulated absorption spectra. The refractive index is then modified. The bandgap of the material is changed because of the discretization of the electron energy, which can be controlled by the nanometers size particles. Such quantum dots behave like atoms and become luminescent. The lifetime of the electron in the excited states are much larger than in continuous energy bands. Electrons in coupled quantum dots behave as they do in molecules. Many applications

  13. Laser Induced Damage in Optical Materials: 1979.

    DTIC Science & Technology

    1980-07-01

    phous alloy a-Si:H which was deposited in Ar/H2 ’ Principal deposition parameters affecting the resulting material properties were substrate...the present study, ion implantation of aluminum into copper has been used as a tool to inhibit oxidation and thus improve the surface properties with...percent of 10-20% if equal sputtering of the alloying com- pounds is assumed, were used. Concerning the penetration of the energetic aluminum ions into

  14. Ultralight Weight Optical Systems Using Nano-Layered Synthesized Materials

    NASA Technical Reports Server (NTRS)

    Clark, Natalie; Breckinridge, James

    2014-01-01

    Optical imaging is important for many NASA science missions. Even though complex optical systems have advanced, the optics, based on conventional glass and mirrors, require components that are thick, heavy and expensive. As the need for higher performance expands, glass and mirrors are fast approaching the point where they will be too large, heavy and costly for spacecraft, especially small satellite systems. NASA Langley Research Center is developing a wide range of novel nano-layered synthesized materials that enable the development and fabrication of ultralight weight optical device systems that enable many NASA missions to collect science data imagery using small satellites. In addition to significantly reducing weight, the nano-layered synthesized materials offer advantages in performance, size, and cost.

  15. Sensitive and absolute absorption measurements in optical materials and coatings by laser-induced deflection technique

    NASA Astrophysics Data System (ADS)

    Mühlig, Christian; Bublitz, Simon

    2012-12-01

    The laser-induced deflection (LID) technique, a photo-thermal deflection setup with transversal pump-probe-beam arrangement, is applied for sensitive and absolute absorption measurements of optical materials and coatings. Different LID concepts for bulk and transparent coating absorption measurements, respectively, are explained, focusing on providing accurate absorption data with only one measurement and one sample. Furthermore, a new sandwich concept is introduced that allows transferring the LID technique to very small sample geometries and to significantly increase the sensitivity for materials with weak photo-thermal responses. For each of the different concepts, a representative application example is given. Particular emphasis is placed on the importance of the calibration procedure for providing absolute absorption data. The validity of an electrical calibration procedure for the LID setup is proven using specially engineered surface absorbing samples. The electrical calibration procedure is then applied to evaluate two other approaches that use either doped samples or highly absorptive reference samples.

  16. Optical fiber sensors for materials and structures characterization

    NASA Technical Reports Server (NTRS)

    Lindner, D. K.; Claus, R. O.

    1991-01-01

    The final technical report on Optical Fiber Sensors for Materials and Structures Characterization, covering the period August 1990 through August 1991 is presented. Research programs in the following technical areas are described; sapphire optical fiber sensors; vibration analysis using two-mode elliptical core fibers and sensors; extrinsic Fabry-Perot interferometer development; and coatings for fluorescent-based sensor. Research progress in each of these areas was substantial, as evidenced by the technical publications which are included as appendices.

  17. Nanorod Material Developed for Use as an Optical Sensor Platform

    NASA Technical Reports Server (NTRS)

    Bencic, Timothy J.

    2005-01-01

    Optical sensors are becoming increasingly important in the development of new nonintrusive or embedded sensors. The use of light and material optical properties helps us measure unknown parameters such as temperature, pressure, flow, or chemical species. The focus of this work is to develop new nanostructure platforms upon which optical sensors can be constructed. These nanorods are synthesized oxides that form a base structure to which luminescent sensing dyes or dopants can be attached or embedded. The nanorod structure allows for a much greater open area than closed or polymer-based sensors do, enabling a much faster contact of the measured species with the luminescent sensor and, thus, a potentially faster measurement.

  18. Optical properties of plastic materials for medical vision applications

    NASA Astrophysics Data System (ADS)

    Sultanova, N. G.; Kasarova, S. N.; Nikolov, I. D.

    2012-12-01

    Several types of optical polymer materials suitable for ophthalmic or medical vision applications have been studied. We have measured refractive indices of studied plastics at various wavelengths in the visible and near-infrared spectral regions. Important optical characteristics as Abbe numbers, dispersion coefficients and curves, principal and relative partial dispersion have been evaluated. Calculated refractometric data at many laser emission wavelengths used for medical surgery, therapy and diagnostics is included. As an example of a medical vision application of plastics, optical design of a micro-triplet for use in disposable endoscopes is presented.

  19. Mechanistic studies for optical switching materials for space environments

    NASA Astrophysics Data System (ADS)

    Rayfield, George W.; Sarkar, Abhijit; Rahman, Salma; Godschalx, James P.; Taylor, Edward W.

    2010-09-01

    Optical power limiters (OPLs) are nonlinear optical (NLO) devices that limit the amount of energy transmitted in an optical system. At low incident optical power or pulse energy, the transmission of the system is high enough to allow nominal operation of the system. At high incident optical power or pulse energy, the transmission decreases to protect sensitive components such as optical receivers or transmitters. The interest OPLs for use in the space environment is due to the increasingly large number of space based missions and devices that require laser protection from laser beam is coming from, an enemy, misaligned laser in equipment, etc. Temperature and space radiation-induced effects in optical and electronic materials are well known and they can cause disruption in OPL functions, or in the worst case, failure of the sensor. Recently, certain hyperbranched polymer-based composites containing OPL chromophores have been developed that offer high OPL performance and have been shown to function in a simulated + space environment. One novel high performance polymer material containing carbon nanotubes (CNT) covalently attached to the polymer host is promising. Preliminary light scattering measurements suggest that nonlinear scattering is not the primary mechanism for OPL performance.

  20. Evaluation of absorbent materials for use as ad hoc dry decontaminants during mass casualty incidents as part of the UK’s Initial Operational Response (IOR)

    PubMed Central

    Kassouf, Nick; Syed, Sara; Larner, Joanne; Amlôt, Richard

    2017-01-01

    The UK’s Initial Operational Response (IOR) is a revised process for the medical management of mass casualties potentially contaminated with hazardous materials. A critical element of the IOR is the introduction of immediate, on-scene disrobing and decontamination of casualties to limit the adverse health effects of exposure. Ad hoc cleansing of the skin with dry absorbent materials has previously been identified as a potential means of facilitating emergency decontamination. The purpose of this study was to evaluate the in vitro oil and water absorbency of a range of materials commonly found in the domestic and clinical environments and to determine the effectiveness of a small, but representative selection of such materials in skin decontamination, using an established ex vivo model. Five contaminants were used in the study: methyl salicylate, parathion, diethyl malonate, phorate and potassium cyanide. In vitro measurements of water and oil absorbency did not correlate with ex vivo measurements of skin decontamination. When measured ex vivo, dry decontamination was consistently more effective than a standard wet decontamination method (“rinse-wipe-rinse”) for removing liquid contaminants. However, dry decontamination was ineffective against particulate contamination. Collectively, these data confirm that absorbent materials such as wound dressings and tissue paper provide an effective, generic capability for emergency removal of liquid contaminants from the skin surface, but that wet decontamination should be used for non-liquid contaminants. PMID:28152053

  1. Evaluation of absorbent materials for use as ad hoc dry decontaminants during mass casualty incidents as part of the UK's Initial Operational Response (IOR).

    PubMed

    Kassouf, Nick; Syed, Sara; Larner, Joanne; Amlôt, Richard; Chilcott, Robert P

    2017-01-01

    The UK's Initial Operational Response (IOR) is a revised process for the medical management of mass casualties potentially contaminated with hazardous materials. A critical element of the IOR is the introduction of immediate, on-scene disrobing and decontamination of casualties to limit the adverse health effects of exposure. Ad hoc cleansing of the skin with dry absorbent materials has previously been identified as a potential means of facilitating emergency decontamination. The purpose of this study was to evaluate the in vitro oil and water absorbency of a range of materials commonly found in the domestic and clinical environments and to determine the effectiveness of a small, but representative selection of such materials in skin decontamination, using an established ex vivo model. Five contaminants were used in the study: methyl salicylate, parathion, diethyl malonate, phorate and potassium cyanide. In vitro measurements of water and oil absorbency did not correlate with ex vivo measurements of skin decontamination. When measured ex vivo, dry decontamination was consistently more effective than a standard wet decontamination method ("rinse-wipe-rinse") for removing liquid contaminants. However, dry decontamination was ineffective against particulate contamination. Collectively, these data confirm that absorbent materials such as wound dressings and tissue paper provide an effective, generic capability for emergency removal of liquid contaminants from the skin surface, but that wet decontamination should be used for non-liquid contaminants.

  2. A portable, non-focusing optics spectrophotometer (NoFOSpec) for measurements of steady-state absorbance changes in intact plants.

    PubMed

    Sacksteder, C A; Jacoby, M E; Kramer, D M

    2001-01-01

    Kinetically-resolved absorbance measurements during extended, or steady-state illumination are typically hindered by large, light-induced changes in the light-scattering properties of the material. In this work, a new type of portable spectrophotometer, the Non-Focusing Optical Spectrophotometer (NoFOSpec), is introduced, which reduces interference from light-scattering changes and is in a form suitable for fieldwork. The instrument employs a non-focusing optical component, called a compound parabolic concentrator (CPC), to simultaneously concentrate and homogeneously diffuse measuring and actinic light (from light-emitting diode sources) onto the leaf sample. Light passing through the sample is then collected and processed using a subsequent series of CPCs leading to a photodiode detector. The instrument is designed to be compact, lightweight and rugged for field work. The pulsed measuring beam allows for high sensitivity (typically < 100 ppm noise) and time resolution ( approximately 10 mus) measurements in the visible and near infrared spectral regions. These attributes allow high-resolution measurements of signals associated with energization of the thylakoid membrane (the electrochromic shifting of carotenoid pigments), as well as electron transfer, e.g., the 820-nm changes associated with electron transfer through Photosystem I (PS I). In addition, the instrument can be used as a kinetic fluorimeter, e.g., to measure saturation-pulse fluorescence changes indicative of Photosystem II (PS II) quantum efficiency. The instrument is demonstrated by estimating electron and proton fluxes through the photosynthetic apparatus in an intact tobacco leaf, using respectively the saturation-pulse fluorescence changes and dark-interval relaxation kinetics (DIRK) of the electrochromic shift. A linear relationship was found, confirming our earlier results with the laboratory-based diffused-optics flash spectrophotometer, indicating a constant H(+)/e(-) stoichiometry for

  3. Mechanical And Thermal Properties Of Optical Materials - A Review

    NASA Astrophysics Data System (ADS)

    Ballard, Stanley S.

    1980-02-01

    In selecting an optical material, the instrument designer's first consideration is optical properties, especially transmission region but also homogeneity, freedom from birefringence, perhaps refractive index and dispersion. Next in his hierarchy are the other physical properties: mechanical, thermal, and chemical (solubility, for example). In this review article, the several properties are listed, and data sources are given. No single compilation or handbook contains all the desired data, so many references are quoted. This review covers materials useful in the ultraviolet and esuecially the infrared spectral regions; it does not include the standard glasses used in the visible region.

  4. Enantiomeric analysis of beta-pinene and limonene by direct coupling of reversed phase liquid chromatography and gas chromatography using absorbents as packing materials.

    PubMed

    Flores, Gema; Ruiz del Castillo, Maria Luisa; Herraiz, Marta

    2007-11-01

    A method based on the use of absorbents as packing materials inside the interface of the online coupling between RPLC and GC is proposed for the enantiomeric analysis of beta-pinene and limonene in essential oils. For that purpose, a comparison of the RSD, detection limit and recovery provided by two absorbents and one adsorbent is included in this study. The results found in this work proved the validity of absorbents as packing materials in online RPLC-GC to determine minor compounds in complex matrices. In particular, PDMS seemed to be specially useful to analyse nonpolar compounds, such as beta-pinene and limonene, since it provided higher sensitivity for this kind of compounds. The developed method was applied to the evaluation of the natural and non-natural character of commercial essential oils by means of the determination of the enantiomeric composition of beta-pinene and limonene.

  5. Study of the Use of Oxygen-Absorbing Packaging Material to Prolong Shelf-Life of Rations

    DTIC Science & Technology

    2010-05-28

    unlimited. The effectiveness of a new oxygen absorbing packaging technology in modifying the inner atmosphere to very low residual oxygen retarding...attached 3 Summary The effectiveness of a new oxygen absorbing packaging technology in modifying the inner atmosphere to very low residual...packaged products according to product specifications (Phase I); (2) identifying the relationship between food moisture content and activation of

  6. Optical investigation of molecular structure of sophisticated materials for photonics

    NASA Astrophysics Data System (ADS)

    Gnyba, Marcin; Keraenen, Mikko

    2003-10-01

    Permanent development of photonics stimulates a searching for new materials, which have better optical, mechanical and electrical properties. One of the new classes of materials with large application and development potential are hybrid polymers, synthesized in sol-gel technology. Thanks to incorporation of organic components into an in organic network, a combination of advantages of both class of materials became available. Properties of hybrids may be formed in wide range. These materials can be used in photonics to produce planar waveguides, lenses, Bragg gratings and components for integrated optics. Moreover, dielectric layers, coatings and packaging are made from hybrids. Additionally, research to apply them in optical fiber sensors (including bio-sensors) and solid state lasers is underway. However, to obtain a high quality product, a strict control of its molecular structure must be ensured. This is a very difficult task, because of a sophisticated structure of hybrid polymers. To address these problems, optical, non-destructive measurement techniques such as Raman and infrared spectroscopy were used. They are compementary methods, so their simultaneous application, as it was shown in this paper, can significantly increase the amoung of information about molecular structure of materials and process of their synthesis.

  7. Radio-Absorbing Materials

    DTIC Science & Technology

    2007-11-02

    Transliteration Block Italic Transliteratic:. Ae A 4 A, a P p Pp R , r Su 6 B, b C c C S, s 8 B Ba V , v T T T m T.t Fr r a G, g Y y Y y U, u a D P , d...image on the scren^f th ahd -ray i tub ofthez sina I z f. rqrii r be A rns placed on both sides of takeoff and landing strip. System Microvision works...I or in Requester: FTD/TQTR ’I S RA&I Approved for public release; distribution unlimited. TAB b. I)U. , ou c I d II r_. [uistribatto’!/ ,A v ui

  8. Analysis of temperature and thermo-optical properties in optical materials. 1: Cylindrical geometry

    NASA Astrophysics Data System (ADS)

    Tilleman, Michael M.

    2010-11-01

    Modeling of optical and electro-optical devices requires the implementation of material properties over a broad temperature range. Because optical, thermo-optical, elasto-optical and gain properties of solid-state laser materials depend on temperature, their exact magnitude is needed for designing such optical devices. Derived in this paper is a closed form solution to the problems of nonlinear heat transfer and stress field, resulting in expressions for the local temperature, stress and strain, refractive index, trajectories of propagating rays, optical path difference, thermal lensing, tilt and third order aberrations, induced birefringence and depolarization. In the analysis the temperature dependent coefficients were best fitted to existing experimental data. Some examples are presented for thermally induced optical effects in solid-state laser gain-media in the temperature range of 77-770 K. It is found that: for large heat deposition rates the use of the nonlinear solution is uniquely necessary to assess the thermal and optical characteristics, high pumping loads require cryogenic cooling to maintain low thermal lensing and thermally induced dioptric power depends quadratically on the heat rate.

  9. Study of the antifungal potential of novel cellulose/copper composites as absorbent materials for fruit juices.

    PubMed

    Llorens, Amparo; Lloret, Elsa; Picouet, Pierre; Fernandez, Avelina

    2012-08-17

    Cellulose/copper composites with antifungal properties have been synthesized by physical/chemical methods. Physical treatments by heat or by a combination of heat and UV radiation provided composites with metallic copper and excellent interfacial adhesion; in contrast, chemical reduction with borohydride generated small although partially aggregated copper oxide nanoparticles. Copper micro/nano-particles and copper ions (Cu(2+)) were released from the cellulose matrix at an adequate rate to achieve a strong antimicrobial activity against Saccharomyces cerevisiae in in vitro experiments. Moreover, the copper oxide composites showed an excellent antifungal activity in pineapple and melon juice, reducing about 4 log cycles the loads of spoilage-related yeasts and moulds. The metallic copper composites reduced in 4 log cycles the load of yeasts and moulds in pineapple juice, although their antifungal activity was weaker in contact with melon juice. Copper loaded absorbent materials could be selectively implemented during the shelf-life of minimally processed fruits to reduce the number of spoilage-related microorganisms in the drip.

  10. Evaluation of absorbed dose in irradiated sugar-containing plant material (peony roots) by an ESR method

    NASA Astrophysics Data System (ADS)

    Yamaoki, Rumi; Kimura, Shojiro; Ohta, Masatoshi

    2015-12-01

    The relationship between electron spin resonance (ESR) signal intensity of irradiated plant materials and sugar content was investigated by spectral analysis using peony roots. A weak background signal near g=2.005 was observed in the roots. After a 10 kGy irradiation, the ESR line broadened and the intensity increased, and the spectral characteristics were similar to a typical spectrum of irradiated food containing crystalline sugars. The free radical concentration was nearly stable 30 days after irradiation. The spectrum of peony root 30 days after irradiation was simulated using the summation of the intensities of six assumed components: radical signals derived from (a) sucrose, (b) glucose, (c) fructose, (d) cellulose, (e) the background signal near g=2.005 and (f) unidentified component. The simulated spectra using the six components were in agreement with the observed sample spectra. The intensity of sucrose radical signal in irradiated samples increased proportionally up to 20 kGy. In addition, the intensity of sucrose radical signals was strongly correlated with the sucrose contents of the samples. The results showed that the radiation sensitivity of sucrose in peony roots was influenced little by other plant constituents. There was also a good correlation between the total area of the spectra and the sucrose content, because the sucrose content was higher than that of other sugars in the samples. In peony roots, estimation of the absorbed dose from the ESR signal intensity may be possible by a calibration method based on the sucrose content.

  11. Optical Waveguide Solar Energy System for Lunar Materials Processing

    NASA Technical Reports Server (NTRS)

    Nakamura, T.; Case, J. A.; Senior, C. L.

    1997-01-01

    This paper discusses results of our work on development of the Optical Waveguide (OW) Solar Energy System for Lunar Materials Processing. In the OW system as shown, solar radiation is collected by the concentrator which transfers the concentrated solar radiation to the OW transmission line consisting of low-loss optical fibers. The OW line transmits the solar radiation to the thermal reactor of the lunar materials processing plant. The feature of the OW system are: (1) Highly concentrated solar radiation (up to 104 suns) can be transmitted via flexible OW lines directly into the thermal reactor for materials processing: (2) Solar radiation intensity or spectra can be tailored to specific materials processing steps; (3) Provide solar energy to locations or inside of enclosures that would not otherwise have an access to solar energy; and (4) The system can be modularized and can be easily transported to and deployed at the lunar base.

  12. A new method to retrieve spectral absorption coefficient of highly-scattering and weakly-absorbing materials

    NASA Astrophysics Data System (ADS)

    Dombrovsky, Leonid A.

    2016-03-01

    A significant uncertainty in the absorption coefficient of highly scattering dispersed materials is typical in the spectral ranges of very weak absorption. The traditional way to identify the main absorption and scattering characteristics of semi-transparent materials is based on spectral measurements of normal-hemispherical reflectance and transmittance for the material sample. Unfortunately this way cannot be used in the case of in vivo measurements of optical properties of biological tissues. A method suggested in the present paper is based on thermal response to the periodic radiative heating of the open surface of a semi-transparent material. It is shown that the period of a variation of the surface temperature is sensitive to the value of an average absorption coefficient in the surface layer. As a result, the monochromatic external irradiation combined with the surface temperature measurements can be used to retrieve the spectral values of absorption coefficient. Possible application of this method to porous semi-transparent ceramics is considered. An example problem is also solved to illustrate the applicability of this method to human skin. The approach suggested enables one to estimate an average absorption coefficient of human skin of a patient just before the thermal processing.

  13. Are Extracted Materials Truly Representative of Original Samples? Impact of C18 Extraction on CDOM Optical and Chemical Properties.

    PubMed

    Andrew, Andrea A; Del Vecchio, Rossana; Zhang, Yi; Subramaniam, Ajit; Blough, Neil V

    2016-01-01

    Some properties of dissolved organic matter (DOM) and chromophoric dissolved organic matter (CDOM) can be easily measured directly on whole waters, while others require sample concentration and removal of natural salts. To increase CDOM content and eliminate salts, solid phase extraction (SPE) is often employed. Biases following extraction and elution are inevitable, thus raising the question of how truly representative the extracted material is of the original. In this context, we investigated the wavelength dependence of extraction efficiency for C18 cartridges with respect to CDOM optical properties using samples obtained from the Middle Atlantic Bight (MAB) and the Equatorial Atlantic Ocean (EAO). Further, we compared the optical changes of C18 extracts and the corresponding whole water following chemical reduction with sodium borohydride (NaBH4). C18 cartridges preferentially extracted long-wavelength absorbing/emitting material for samples impacted by riverine input. Extraction efficiency overall decreased with offshore distance away from riverine input. Spectral slopes of C18-OM samples were also almost always lower than those of their corresponding CDOM samples supporting the preferential extraction of higher molecular weight absorbing material. The wavelength dependence of the optical properties (absorption, fluorescence emission, and quantum yield) of the original water samples and their corresponding extracted material were very similar. C18 extracts and corresponding water samples further exhibited comparable optical changes following NaBH4 reduction, thus suggesting a similarity in nature (structure) of the optically active extracted material, independent of geographical locale. Altogether, these data suggested a strong similarity between C18 extracts and corresponding whole waters, thus indicating that extracts are representative of the CDOM content of original waters.

  14. Magneto-optical activity in organic thin film materials

    NASA Astrophysics Data System (ADS)

    Vleugels, Rick; de Vega, Laura; Brullot, Ward; Verbiest, Thierry; Gómez-Lor, Berta; Gutierrez-Puebla, Enrique; Hennrich, Gunther

    2016-12-01

    A series of CF3-capped phenylacetylenes with varying symmetry is obtained by a conventional palladium-catalyzed cross-coupling protocol. The phenylacetylene targets form thin films both, liquid crystalline (LC) and crystalline in nature depending on their molecular structure. The magneto-optical activity of the resulting organic material is extraordinarily high as proved by Faraday rotation spectroscopy on thin film devices.

  15. Distribution of absorbed doses in the materials irradiated by ''RHODOTRON'' electron accelerator: Experiment and Monte Carlo simulations

    SciTech Connect

    Oleg E. Krivosheev et al.

    2001-07-02

    This paper describes the experimental setup and presents studies of absorbed doses in different metals and dielectrics along with corresponding Monte Carlo energy deposition simulations. Experiments were conducted using a 5 MeV electron accelerator. We used several Monte Carlo code systems, namely MARS, MCNP, and GEANT to simulate the absorbed doses under the same conditions as in experiment. We compare calculated and measured high and low absorbed doses (from few kGy to hundreds kGy) and discuss the applicability of these computer codes for applied accelerator dosimetry.

  16. Oxidation processes in magneto-optic and related materials

    NASA Technical Reports Server (NTRS)

    Lee, Paul A.; Armstrong, Neal R.; Danzinger, James L.; England, Craig D.

    1992-01-01

    The surface oxidation processes of thin films of magneto-optic materials, such as the rare-earth transition metal alloys have been studied, starting in ultrahigh vacuum environments, using surface analysis techniques, as a way of modeling the oxidation processes which occur at the base of a defect in an overcoated material, at the instant of exposure to ambient environments. Materials examined have included FeTbCo alloys, as well as those same materials with low percentages of added elements, such a Ta, and their reactivities to both O2 and H2O compared with materials such as thin Fe films coated with ultrathin adlayers of Ti. The surface oxidation pathways for these materials is reviewed, and XPS data presented which indicates the type of oxides formed, and a critical region of Ta concentration which provides optimum protection.

  17. 3D Printing Optical Engine for Controlling Material Microstructure

    NASA Astrophysics Data System (ADS)

    Huang, Wei-Chin; Chang, Kuang-Po; Wu, Ping-Han; Wu, Chih-Hsien; Lin, Ching-Chih; Chuang, Chuan-Sheng; Lin, De-Yau; Liu, Sung-Ho; Horng, Ji-Bin; Tsau, Fang-Hei

    Controlling the cooling rate of alloy during melting and resolidification is the most commonly used method for varying the material microstructure and consequently the resuling property. However, the cooling rate of a selective laser melting (SLM) production is restricted by a preset optimal parameter of a good dense product. The head room for locally manipulating material property in a process is marginal. In this study, we invent an Optical Engine for locally controlling material microstructure in a SLM process. It develops an invovative method to control and adjust thermal history of the solidification process to gain desired material microstucture and consequently drastically improving the quality. Process parameters selected locally for specific materials requirement according to designed characteristics by using thermal dynamic principles of solidification process. It utilize a technique of complex laser beam shape of adaptive irradiation profile to permit local control of material characteristics as desired. This technology could be useful for industrial application of medical implant, aerospace and automobile industries.

  18. Absorbing aerosols over Asia: A Geophysical Fluid Dynamics Laboratory general circulation model sensitivity study of model response to aerosol optical depth and aerosol absorption

    NASA Astrophysics Data System (ADS)

    Randles, C. A.; Ramaswamy, V.

    2008-11-01

    Forcing by absorbing atmospheric black carbon (BC) tends to heat the atmosphere, cool the surface, and reduce the surface latent and sensible heat fluxes. BC aerosol can have a large impact on regional climates and the hydrologic cycle. However, significant uncertainties remain concerning the increases in (1) the total amount of all aerosol species and (2) the amount of aerosol absorption that may have occurred over the 1950-1990 period. Focusing on south and east Asia, the sensitivity of a general circulation model's climate response (with prescribed sea surface temperatures and aerosol distributions) to such changes is investigated by considering a range of both aerosol absorption and aerosol extinction optical depth increases. We include direct and semidirect aerosol effects only. Precipitation changes are less sensitive to changes in aerosol absorption optical depth at lower aerosol loadings. At higher-extinction optical depths, low-level convergence and increases in vertical velocity overcome the stabilizing effects of absorbing aerosols and enhance the monsoonal circulation and precipitation in northwestern India. In contrast, the presence of increases in only scattering aerosols weakens the monsoonal circulation and inhibits precipitation here. Cloud amount changes can enhance or counteract surface solar flux reduction depending on the aerosol loading and absorption, with the changes also influencing the surface temperature and the surface energy balance. The results have implications for aerosol reduction strategies in the future that seek to mitigate air pollution concerns. At higher optical depths, if absorbing aerosol is present, reduction of scattering aerosol alone has a reduced effect on precipitation changes, implying that reductions in BC aerosols should be undertaken at the same time as reductions in sulfate aerosols.

  19. Evaluation of material dispersion using a nanosecond optical pulse radiator.

    PubMed

    Horiguchi, M; Ohmori, Y; Miya, T

    1979-07-01

    To study the material dispersion effects on graded-index fibers, a method for measuring the material dispersion in optical glass fibers has been developed. Nanosecond pulses in the 0.5-1.7-microm region are generated by a nanosecond optical pulse radiator and grating monochromator. These pulses are injected into a GeO(2)-P(2)0(5)-doped silica graded-index fiber. Relative time delay changes between different wavelengths are used to determine material dispersion, core glass refractive index, material group index, and optimum profile parameter of the graded-index fiber. From the measured data, the optimum profile parameter on the GeO(2)-P(2)O(5)-doped silica graded-index fiber could be estimated to be 1.88 at 1.27 microm of the material dispersion free wavelength region and 1.82 at 1.55 microm of the lowest-loss wavelength region in silica-based optical fiber waveguides.

  20. Ultrasonic processing of hard materials for conformal optics

    NASA Astrophysics Data System (ADS)

    Fess, Edward; Bechtold, Rob; Bechtold, Mike; Wolfs, Frank

    2013-06-01

    Hard ceramic optical materials such as sapphire, ALON, Spinel, or PCA can present a significant challenge in manufacturing precision optical components due to their tough mechanical properties. These are also the same mechanical properties that make them desirable materials when used in harsh environments. Tool wear and tool loading conditions during the grinding process for these materials can be especially problematic. Because of this, frequent dressing and reshaping of grinding wheels is often required. OptiPro systems is developing an ultrasonic grinding process called OptiSonic to minimize the forces during grinding and make the grinding process more efficient. The ultrasonic vibration of the grinding wheel allows for a grinding process that has the capacity for longer tool life and reduced tool wear for a more deterministic process. This presentation will discuss the OptiSonic process and present current results.

  1. Homogeneity of material and optical properties in HEM grown sapphire

    NASA Astrophysics Data System (ADS)

    Stout, M.; Hibbard, D.

    2015-09-01

    Sapphire crystal boules, approximately 34 cm in diameter and 22 cm tall, grown by the Heat Exchanger Method (HEM) are currently being sliced, ground and polished for use as window substrates in a variety of aerospace applications. As the need for larger volumes of higher quality material increases, it is necessary to evaluate and understand the homogeneity of optical and material properties within sapphire boules to ensure the needs of the industry can be met. The optical homogeneity throughout the full useable thickness of a representative sapphire boule was evaluated by measuring the transmitted wavefront error of multiple thin slices. This approach allowed the creation of a full-volume three-dimensional homogeneity map. Additionally, the uniformity of other critical characteristics of the material was evaluated at multiple locations within a boule. Specific properties investigated were equibiaxial flexural strength, index of refraction, Knoop hardness, coefficient of thermal expansion and modulus of elasticity. The results of those evaluations will be reported.

  2. Laser-assisted manufacturing of micro-optical volume elements for enhancing the amount of light absorbed by solar cells in photovoltaic modules

    NASA Astrophysics Data System (ADS)

    Peharz, Gerhard; Kuna, Ladislav; Leiner, Claude

    2015-03-01

    The laser-generation of micro-optical volume elements is a promising approach to decrease the optical shadowing of front side metal contacts of solar cells. Focusing a femtosecond laser beam into the volume of the encapsulation material causes a local modification its optical constants. Suchlike fabricated micro-optical elements can be used to decrease the optical shadowing of the front side metallization of c-Si solar cells. Test samples comprising of a sandwich structure of a glass sheet with metallic grid-lines, an Ethylene-vinyl acetate (EVA) encapsulant and another glass sheet were manufactured in order to investigate the optical performance of the volume optics. Transmission measurements show that the shadowing of the metalling grid-lines is substantially decreased by the micro-optical volume elements created in the EVA bulk right above the grid-fingers. A detailed investigation of the optical properties of these volume elements was performed: (i) experimentally on the basis of goniometric measurements, as well as (ii) theoretically by applying optical modelling and optimization procedures. This resulted in a better understanding of the effectiveness of the optical volume elements in decreasing the optical shadowing of metal grid lines on the active cell surfaces. Moreover, results of photovoltaic mini-modules with incorporated micro-optical volume elements are presented. Results of optical simulation and Laser Beam Induced Current (LBIC) experiments show that the losses due to the grid fingers can be reduced by about 50%, when using this fs-laser structuring approach for the fabrication of micro-optical volume elements in the EVA material.

  3. Ultraprecision grinding of optical materials for high-power lasers

    NASA Astrophysics Data System (ADS)

    Namba, Yoshiharu; Yoshida, Kunio; Yoshida, Hidetsugu; Nakai, Sadao

    1998-04-01

    Grinding is considered to be a rough machining process in the field of optics; a polishing process must follow the grinding process for getting optical-quality surfaces. An ultraprecision surface grinder with hydrostatic oil bearings and a glass-ceramic spindle of extremely low thermal expansion was developed to get smooth optical surfaces without any polishing process. Various optical materials such as NbF1, BK7, LHG08 fused silica, KTP, KDP and CLBO were ground into optical surfaces after empirically determining the conditions required to attain ductile-mode grinding. An extremely smooth surface less than 0.1 nm rms was obtained on BK7 glass by the ultraprecision grinding process. The laser-induced damage threshold was measured on variously finished LHG-8 laser glass at (lambda) equals 1.053 micrometers and 1-ns pulse width. The damage threshold was measured at 22.2 J/cm2 on a ground surface with the polarization parallel to the grinding direction. This number is higher than that obtained by optical polish. The damage threshold of 293 J/cm2 was also obtained on a ground LHG-8 glass surface at (lambda) equals 1.053 micrometers and 30-ns pulse width.

  4. Highly Non-Linear Optical (NLO) organic crystals and films. Electrooptical organic materials

    NASA Technical Reports Server (NTRS)

    Mcmanus, Samuel P.; Rosenberger, Franz; Matthews, John

    1987-01-01

    Devices employing nonlinear optics (NLO) hold great promise for important applications in integrated optics, optical information processing and telecommunications. Properly designed organics possess outstanding optical and electrooptical properties which will substantially advance many technologies including electrooptical switching, optical amplification for communications, and parallel processing for hybrid optical computers. A brief comparison of organic and inorganic materials is given.

  5. Annealing effect on the structural and optical properties of Cr/α-Cr2O3 monodispersed particles based solar absorbers

    NASA Astrophysics Data System (ADS)

    Khamlich, S.; McCrindle, R.; Nuru, Z. Y.; Cingo, N.; Maaza, M.

    2013-01-01

    A cost-effective and environmentally friendly green chemical method, the so-called aqueous chemical growth (ACG) method, was used to deposit chromium/alpha-chromium(III) oxide, Cr/α-Cr2O3, monodispersed particles, for solar absorbers applications. The deposited particles were annealed at various temperatures in a hydrogen atmosphere for 2 h to study the annealing temperature dependence of the structural, chemical and optical properties of the particles grown on tantalum substrates. The deposited Cr/α-Cr2O3 was characterized by X-ray diffraction (XRD), attenuated total reflection (ATR), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and diffuse reflectance UV-vis-NIR spectroscopy. The XRD and ATR analysis indicated that by increasing annealing temperature, the particles crystallinity was improved and Ta2O5 was formed around 600 °C, due to the fast oxygen diffusion from the deposited α-Cr2O3 toward the tantalum substrate. The optical measurements show that samples annealed at 400 and 500 °C exhibit the targeted high absorbing optical characteristics of "Black chrome", while those annealed below 400 °C and above 500 °C show a significant low absorptivity and high emissivity.

  6. Optical materials technology for energy efficiency and solar energy conversion VI; Proceedings of the Meeting, San Diego, CA, Aug. 18, 19, 1987

    SciTech Connect

    Lampert, C.M.

    1987-01-01

    Recent advances in optical materials for energy conversion are discussed in reviews and reports. Sections are devoted to transparent IR reflectors and large-area deposition technology; optical switching materials; holographic films and reflector technology; and absorbers, photovoltaics, and solar materials. Topics addressed include bendable Ag-based low-emissivity coating on glass, plasma oxidation of Ag and Zn in low-emissivity stacks, smart window coatings, improved colored-state reflectivity in lithiated WO3 films, photochromic and thermochromic pigments for solar absorbing-reflecting coatings, the design and optimization of holographic solar concentrators, the properties of black cobalt coatings, and interface states and Fermi-level pinning in CdSe thin-film solar cells.

  7. Absorber for terahertz radiation management

    SciTech Connect

    Biallas, George Herman; Apeldoorn, Cornelis; Williams, Gwyn P.; Benson, Stephen V.; Shinn, Michelle D.; Heckman, John D.

    2015-12-08

    A method and apparatus for minimizing the degradation of power in a free electron laser (FEL) generating terahertz (THz) radiation. The method includes inserting an absorber ring in the FEL beam path for absorbing any irregular THz radiation and thus minimizes the degradation of downstream optics and the resulting degradation of the FEL output power. The absorber ring includes an upstream side, a downstream side, and a plurality of wedges spaced radially around the absorber ring. The wedges form a scallop-like feature on the innermost edges of the absorber ring that acts as an apodizer, stopping diffractive focusing of the THz radiation that is not intercepted by the absorber. Spacing between the scallop-like features and the shape of the features approximates the Bartlett apodization function. The absorber ring provides a smooth intensity distribution, rather than one that is peaked on-center, thereby eliminating minor distortion downstream of the absorber.

  8. Diffused holographic information storage and retrieval using photorefractive optical materials

    NASA Astrophysics Data System (ADS)

    McMillen, Deanna Kay

    Holography offers a tremendous opportunity for dense information storage, theoretically one bit per cubic wavelength of material volume, with rapid retrieval, of up to thousands of pages of information simultaneously. However, many factors prevent the theoretical storage limit from being reached, including dynamic range problems and imperfections in recording materials. This research explores new ways of moving closer to practical holographic information storage and retrieval by altering the recording materials, in this case, photorefractive crystals, and by increasing the current storage capacity while improving the information retrieved. As an experimental example of the techniques developed, the information retrieved is the correlation peak from an optical recognition architecture, but the materials and methods developed are applicable to many other holographic information storage systems. Optical correlators can potentially solve any signal or image recognition problem. Military surveillance, fingerprint identification for law enforcement or employee identification, and video games are but a few examples of applications. A major obstacle keeping optical correlators from being universally accepted is the lack of a high quality, thick (high capacity) holographic recording material that operates with red or infrared wavelengths which are available from inexpensive diode lasers. This research addresses the problems from two positions: find a better material for use with diode lasers, and reduce the requirements placed on the material while maintaining an efficient and effective system. This research found that the solutions are new dopants introduced into photorefractive lithium niobate to improve wavelength sensitivities and the use of a novel inexpensive diffuser that reduces the dynamic range and optical element quality requirements (which reduces the cost) while improving performance. A uniquely doped set of 12 lithium niobate crystals was specified and

  9. Liquid Cryogen Absorber for MICE

    SciTech Connect

    Baynham, D.E.; Bish, P.; Bradshaw, T.W.; Cummings, M.A.; Green,M.A.; Ishimoto, S.; Ivaniouchenkov, I.; Lau, W.; Yang, S.Q.; Zisman, M.S.

    2005-08-20

    The Muon Ionization Cooling Experiment (MICE) will test ionization cooling of muons. In order to have effective ionization cooling, one must use an absorber that is made from a low-z material. The most effective low z materials for ionization cooling are hydrogen, helium, lithium hydride, lithium and beryllium, in that order. In order to measure the effect of material on cooling, several absorber materials must be used. This report describes a liquid-hydrogen absorber that is within a pair of superconducting focusing solenoids. The absorber must also be suitable for use with liquid helium. The following absorber components are discussed in this report; the absorber body, its heat exchanger, the hydrogen system, and the hydrogen safety. Absorber cooling and the thin windows are not discussed here.

  10. Surface finish and subsurface damage in polycrystalline optical materials

    NASA Astrophysics Data System (ADS)

    Shafrir, Shai Negev

    We measure and describe surface microstructure and subsurface damage (SSD) induced by microgrinding of hard metals and hard ceramics used in optical applications. We examine grinding of ceramic materials with bonded abrasives, and, specifically, deterministic microgrinding (DMG). DMG, at fixed nominal infeed rate and with bound diamond abrasive tools, is the preferred technique for optical fabrication of ceramic materials. In DMG material removal is by microcracking. DMG provides cost effective high manufacturing rates, while attaining higher strength and performance, i.e., low level of subsurface damage (SSD). A wide range of heterogeneous materials of interest to the optics industry were studied in this work. These materials include: A binderless tungsten carbide, nonmagnetic Ni-based tungsten carbides, magnetic Co-based tungsten carbides, and, in addition, other hard optical ceramics, such as aluminum oxynitride (Al23O27N5/ALON), polycrystalline alumina (Al2O3/PCA), and chemical vapor deposited (CVD) silicon carbide (Si4C/SiC). These materials are all commercially available. We demonstrate that spots taken with magnetorheological finishing (MRF) platforms can be used for estimating SSD depth induced by the grinding process. Surface morphology was characterized using various microscopy techniques, such as: contact interferometer, noncontact white light interferometer, light microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). The evolution of surface roughness with the amount of material removed by the MRF process, as measured within the spot deepest point of penetration, can be divided into two stages. In the first stage the induced damaged layer and associated SSD from microgrinding are removed, reaching a low surface roughness value. In the second stage we observe interaction between the MRF process and the material's microstructure as MRF exposes the subsurface without introducing new damage. Line scans taken parallel to the MR

  11. Numerical simulation of dual-loss-modulated Q-switched and mode-locked laser with an acousto-optic and Cr4+:YAG saturable absorber.

    PubMed

    Zhao, Shengzhi; Li, Guiqiu; Li, Dechun; Yang, Kejian; Li, Yufei; Li, Ming; Li, Tao; Zhang, Gang; Cheng, Kang

    2010-04-01

    By considering the influence of the turn-off time and the modulation frequency of the acousto-optic (AO) modulator as well as the Gaussian spatial distribution of the photon density, we give a developed rate equation model for a diode-pumped dual-loss-modulated Q-switched and mode-locked (QML) Nd:GdVO(4) laser with AO modulator and Cr(4+):YAG saturable absorber. With this developed model, the dual-loss-modulated QML laser characteristics, such as pulse width and pulse energy, can be numerically simulated, and the theoretical evaluations are in good agreement with the experimental results.

  12. Evaluation of Pyro-optic Materials for Infrared Imaging

    NASA Astrophysics Data System (ADS)

    Pandey, R. K.; Kotru, Sushma; Song, Xiuyu; Donnelly, David

    2004-03-01

    Infrared detectors are needed for a wide range of applications. IR detectors operate either on the principles of photon detection or pyroelectric detection. Both these systems have their respective advantages and disadvantages. However, both of them inherently have difficulties in management of noise to signal ratio and in read-out circuitory. One of the most serious handicaps of photon detectors is requirement of cryogenic cooling for satisfactory operation. In this respect uncooled pyroelectric detectors operating at above room temperature have an advantage. An alternative to these approaches can be pyro-optic based detectors. Only a handful of materials have been found with some satisfactory level of pyro-optic coefficients appropriate for imaginig devices. Some of them are: antimony-sulfo-iodide (SbSI), molybdenum sulfide (MoS2), bismuth vanadate (BiVO4) and Pb-based titanates. Pyrooptic coefficients of these materials have been reported using presumably bulk single crystals. However, no such data are available for their thin films which would be very important for light weight integrated structured devices.In this paper we will describe the parameters and optimization protocol for the growh of thin films of these materials on thermally insulating substrates. We will also discuss their structural, electrical and optical properties. Our investigations suggest that SbSI, BiVO4 and PNZT films are attractive options for advancing the IR detecting technology by utilizing the pyro-optic effect. Integrated thin film structures might lead to the fabrication of light weight, low cost, noise immune and efficient imaging devices based on pyro-optic properties. This research is sponsored by the DEPSCoR program of the U.S. Army Research Office.

  13. Method and system for processing optical materials for high power laser systems

    SciTech Connect

    Demos, Stavros G; Raman, Rajesh; Negres, Raluca A

    2015-02-03

    A method of determining conditioning pulse parameters for an optical element includes directing a pump pulse to impinge on the optical element and directing a probe pulse to impinge on the optical element. The method also includes determining a first time associated with an onset of electronic excitation leading to formation of an absorbing region of the optical element and determining a second time associated with expansion of the absorbing region of the optical element. The method further includes defining a turn-off time for a conditioning pulse between the first time and the second time. According to embodiments of the present invention, pulse shaping of the conditioning pulse enables laser conditioning of optical elements to achieve improvements in their laser induced damage threshold.

  14. Optical Sensors for Biomolecules Using Nanoporous Sol-Gel Materials

    NASA Technical Reports Server (NTRS)

    Fang, Jonathan; Zhou, Jing C.; Lan, Esther H.; Dunn, Bruce; Gillman, Patricia L.; Smith, Scott M.

    2004-01-01

    An important consideration for space missions to Mars is the ability to detect biosignatures. Solid-state sensing elements for optical detection of biological entities are possible using sol-gel based biologically active materials. We have used these materials as optical sensing elements in a variety of bioassays, including immunoassays and enzyme assays. By immobilizing an appropriate biomolecule in the sol-gel sensing element, we have successfully detected analytes such as amino acids and hormones. In the case of the amino acid glutamate, the enzyme glutamate dehydrogenase was the immobilized molecule, whereas in the case of the hormone cortisol, an anti-cortisol antibody was immobilized in the sensing element. In this previous work with immobilized enzymes and antibodies, excellent sensitivity and specificity were demonstrated in a variety of formats including bulk materials, thin films and fibers. We believe that the sol-gel approach is an attractive platform for bioastronautics sensing applications because of the ability to detect a wide range of entities such as amino acids, fatty acids, hopanes, porphyrins, etc. The sol-gel approach produces an optically transparent 3D silica matrix that forms around the biomolecule of interest, thus stabilizing its structure and functionality while allowing for optical detection. This encapsulation process protects the biomolecule and leads to a more "rugged" sensor. The nanoporous structure of the sol-gel matrix allows diffusion of small target molecules but keeps larger, biomolecules immobilized in the pores. We are currently developing these biologically active sol-gel materials into small portable devices for on-orbit cortisol detection

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

    SciTech Connect

    Appelbaum, Ian

    2011-07-05

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

  16. Self-Assembled Soft Optical Negative Index Materials

    DTIC Science & Technology

    2008-08-05

    Nanorods by Lyotropic Chromonic Materials’, Langmuir, 24 (2008), 13833-37. [15]. A. B. Golovin , and O. D. Lavrentovich, ’Electrically...Reconfigurable Optical Metamaterial Based on Colloidal Dispersion of Metal Nanorods in Dielectric Fluid’, Applied Physics Letters, 95 (2009) [16]. A. B. Golovin ...of Metal Nano-Rods in Dielectric Fluids’, Liquid Crystals Xiv, 7775 (2010) [17]. A. B. Golovin , J. Xiang, H. S. Park, L. Tortora, Y. A. Nastishin

  17. Advances in optical property measurements of spacecraft materials

    NASA Technical Reports Server (NTRS)

    Smith, Charles A.; Dever, Joyce A.; Jaworske, Donald A.

    1997-01-01

    Some of the instruments and experimental approaches, used for measuring the optical properties of thermal control systems, are presented. The instruments' use in studies concerning the effects of combined contaminants and space environment on these materials, and in the qualification of hardware for spacecraft, are described. Instruments for measuring the solar absorptance and infrared emittance offer improved speed, accuracy and data handling. A transient method for directly measuring material infrared emittance is described. It is shown that oxygen exposure before measuring the solar absorptance should be avoided.

  18. Nonlinear absorption and optical damage threshold of carbon-based nanostructured material embedded in a protein

    NASA Astrophysics Data System (ADS)

    Janulewicz, K. A.; Hapiddin, A.; Joseph, D.; Geckeler, K. E.; Sung, J. H.; Nickles, P. V.

    2014-12-01

    Physical processes in laser-matter interaction used to be determined by generation of fast electrons resulting from efficient conversion of the absorbed laser radiation. Composite materials offer the possibility to control the absorption by choice of the host material and dopants. Reported here strong absorption of ultrashort laser pulse in a composite carbon-based nanomaterial including single-walled carbon nanotubes (SWCNTs) or multilayer graphene was measured in the intensity range between 1012 and 1016 W cm-2. A protein (lysozyme) was used as the host. The maximum absorption of femtosecond laser pulse has reached 92-96 %. The optical damage thresholds of the coatings were registered at an intensity of (1.1 ± 0.5) × 1013 W cm-2 for the embedded SWCNTs and at (3.4 ± 0.3) × 1013 W cm-2 for the embedded graphene. Encapsulated variant of the dispersed nanomaterial was investigated as well. It was found that supernatant protein in the coating material tends to dominate the absorption process, independently of the embedded nanomaterial. The opposite was observed for the encapsulated material.

  19. Development of Optical Diagnostic Techniques for Microgravity Materials Processing

    NASA Technical Reports Server (NTRS)

    Cha, Soyoung Stephen

    1999-01-01

    Materials processing including crystal growth, either under a gravity environment on ground or a microgravity environment in space, involves complicated phenomena of fluid motions in gas or liquid phases as well as interaction of various species. To obtain important physical insight, it is very necessary to provide gross-field optical diagnostics for monitoring various physical properties. Materials processing inhibits easy access by ordinary instruments and thus characterizing gross-field physical properties is very challenging. Typical properties of importance can be fluid velocity, temperature, and species concentration for fluids, and surface topology and defects for solids. Observing surface grow rate during crystal growth is also important. Material microstructures, i.e., integrity of crystal structures, is strongly influenced by the existence of thermally-induced flow as well as local nucleation of particles during solidification, which may act in many detrimental ways. In both ground-based and microgravity experiments, the nature of product property changes resulting from three-dimensional fluid or particle motions need be characterized. Gross-field diagnostics is thus required to identify their effects on product defects and process deficiencies. The quantitative visualization techniques can also be used for validation of numerical modeling. For optical nonintrusive gross-field diagnostic techniques, two approaches were developed as summer projects. One optical approach allows us to provide information of species concentration and temperature for monitoring in real time. The other approach, that is, the concept which is formulated for detection of surface topography measurement can provide unprecedented spatial resolution during crystal growth.

  20. Development of manufacturing technologies for hard optical ceramic materials

    NASA Astrophysics Data System (ADS)

    Fess, Edward; DeFisher, Scott; Cahill, Mike; Wolfs, Frank

    2014-05-01

    Hard ceramic optical materials such as sapphire, ALON, Spinel, or PCA can present a significant challenge in manufacturing precision optical components due to their tough mechanical properties. These are also the same mechanical properties that make them desirable materials when used in harsh environments. Premature tool wear or tool loading during the grinding process is a common result of these tough mechanical properties. Another challenge is the requirement to create geometries that conform to the platforms they reside in, but still achieve optical window tolerances for wavefront. These shapes can be complex and require new technologies to control sub aperture finishing techniques in a deterministic fashion. In this paper we will present three technologies developed at OptiPro Systems to address the challenges associated with these materials and complex geometries. The technologies presented will show how Ultrasonic grinding can reduce grinding load by up to 50%, UltraForm Finishing (UFF) and UltraSmooth Finishing (USF) technologies can accurately figure and finish these shapes, and how all of them can be controlled deterministically, with utilizing metrology feedback, by a new Computer Aided Manufacturing (CAM) software package developed by OptiPro called ProSurf.

  1. Optical properties of graphene-based materials in transparent polymer matrices

    NASA Astrophysics Data System (ADS)

    Bayrak, Osman; Ionita, Mariana; Demirci, Emrah; Silberschmidt, Vadim V.

    2016-08-01

    Different aspects of graphene-based materials (GBMs) and GBM-nanocomposites have been investigated due to their intriguing features; one of these features is their transparency. Transparency of GBMs has been of an interest to scientists and engineers mainly with regard to electronic devices. In this study, optical transmittance of structural, purpose-made nanocomposites reinforced with GBMs was analyzed to lay a foundation for optical microstructural characterization of nanocomposites in future studies. Two main types of GBM reinforcements were studied, graphene oxide (GO) and graphite nanoplates (GNPs). The nanocomposites investigated are GO/poly(vinyl alcohol), GO/sodium alginate, and GNP/epoxy with different volume fractions of GBMs. Together with UV-visible spectrophotometry, image-processing-assisted micro and macro photography were used to assess the transparency of GBMs embedded in the matrices. The micro and macro photography methods developed were proven to be an alternative way of measuring light transmittance of semi-transparent materials. It was found that there existed a linear relationship between light absorbance and a volume fraction of GBMs embedded in the same type of polymer matrices, provided that the nanocomposites of interest had the same thicknesses. This suggests that the GBM dispersion characteristics in the same type of polymer are similar and any possible change in crystal structure of polymer due to different volumetric contents of GBM does not have an effect on light transmittance of the matrices. The study also showed that the same types of GBMs could display different optical properties in different matrix materials. The results of this study will help to develop practical microstructural characterization techniques for GBM-based nanocomposites.

  2. Light scattering by dust particles (PROGRA2 experiment): size and structure effects for transparent and absorbing materials

    NASA Astrophysics Data System (ADS)

    Hadamcik, E.; Renard, J.-B.; Lasue, J.; Levasseur-Regourd, A. C.

    2007-08-01

    1- Introduction Cometary and possibly interplanetary dust particles seem to be mainly made of agglomerates of submicron and micron-sized grains. These particles are among the most primitive in our solar system. Regoliths on asteroidal and planetary surfaces seem to be loose materials produced by impinging meteorites on the surface of small bodies. Comparing their physical properties is thus fundamental to understand their evolution. To interpret remote observations of solar light scattered by dust particles and regoliths, it is necessary to use numerical and experimental simulations [1,2,3]. 2- PROGRA2 experiment PROGRA2 instruments are polarimeters; the light sources are two randomly polarized lasers (632.8 nm and 543.5 nm). Levitating particles (in microgravity or lifted by an air-draught) are studied by imaging polarimetry. Details on the instruments can be found in [4,5]. 3- Samples Two kinds of samples are studied: compact particles in the (1-400) micrometer size range and fluffy aggregates in the same size range, made from submicron and micronsized grains. The materials are transparent silica and absorbing carbon. Some deposited particles are huge agglomerates of micron-sized grains produced by random ballistic deposition of single grains [6,7] or produced by evaporation of mixtures in alcohol of fluffy aggregates of submicron-sized grains. Two samples are made of silica spheres coated by a carbonaceous black compound. Cometary analogues are mixtures of silica and amorphous carbon or Mg-Fe silicates mixed with amorphous carbon. 4- Results Phase curves and their main parameters (negative polarization at small phase angles and maximum polarization, Pmax, at 90-100° phase angle) for the different materials will be compared and related to the physical properties. For example, it is well known by numerical simulations and/or by experiments that the maximum polarization decreases when the size (submicrometer range) of the grains increases [2,8,9]. An inverse rule

  3. THz - ToF Optical Layer Analysis (OLA) to determine optical properties of dielectric materials

    NASA Astrophysics Data System (ADS)

    Spranger, Holger; Beckmann, Jörg

    2017-02-01

    Electromagnetic waves with frequencies between 0.1 and 10 THz are described as THz-radiation (T-ray). The ability to penetrate dielectric materials makes T-rays attractive to reveal discontinuities in polymer and ceramic materials. THz-Time Domain Spectroscopy Systems (THz-TDS) are available on the market today which operates with THz-pulses transmitted and received by optically pumped semiconductor antennas. In THz-TDS the travelling time (ToF) and shape of the pulse is changed if it interacts with the dielectric material and its inherent discontinuities. A tomogram of the object under the test can be reconstructed from time of flight diffraction (ToFD) scans if a synthetic focusing aperture (SAFT) algorithm is applied. The knowledge of the base materials shape and optical properties is essential for a proper reconstruction result. To obtain these properties a model is assumed which describes the device under the test as multilayer structure composed of thin layers with different dielectric characteristics. The Optical Layer Analysis (OLA) is able to fulfill these requirements. A short description why the optical properties are crucial for meaningful SAFT reconstruction results will be given first. Afterwards the OLA will be derived and applied on representative samples to discuss and evaluate its benefits and limits.

  4. Examination of an optical transmittance test for photovoltaic encapsulation materials

    SciTech Connect

    Miller, David C.; Bengoechea, Jaione; Bokria, Jayesh G.; Köhl, Michael; Powell, Nick E.; Smith, Michael E.; White, Michael D.; Wilson, Helen Rose; Wohlgemuth, John H.; Dhere, Neelkanth G.; Wohlgemuth, John H.; Lynn, Kevin W.

    2013-09-24

    The optical transmittance of encapsulation materials is a key characteristic for their use in photovoltaic (PV) modules. Changes in transmittance with time in the field affect module performance, which may impact product warranties. Transmittance is important in product development, module manufacturing, and field power production (both immediate and long-term). Therefore, an international standard (IEC 62788-1-4) has recently been proposed by the Encapsulation Task-Group within the Working Group 2 (WG2) of the International Electrotechnical Commission (IEC) Technical Committee 82 (TC82) for the quantification of the optical performance of PV encapsulation materials. Existing standards, such as ASTM E903, are general and more appropriately applied to concentrated solar power than to PV. Starting from the optical transmittance measurement, the solar-weighted transmittance of photon irradiance, yellowness index (which may be used in aging studies to assess durability), and ultraviolet (UV) cut-off wavelength may all be determined using the proposed standard. The details of the proposed test are described. The results of a round-robin experiment (for five materials) conducted at seven laboratories to validate the test procedure using representative materials are also presented. For example, the Encapsulation Group actively explored the measurement requirements (wavelength range and resolution), the requirements for the spectrophotometer (including the integrating sphere and instrument accessories, such as a depolarizer), specimen requirements (choice of glass-superstrate and -substrate), and data analysis (relative to the light that may be used in the PV application). The round-robin experiment identified both intra- and inter-laboratory instrument precision and bias for five encapsulation materials (encompassing a range of transmittance and haze-formation characteristics).

  5. Absorbing and scattering aerosols over the source region of biomass burning emissions: Implications in the assessment of optical and radiative properties

    NASA Astrophysics Data System (ADS)

    Singh, Atinderpal; Srivastava, Rohit; Rastogi, Neeraj; Singh, Darshan

    2016-02-01

    The current study focuses on the assessment of model simulated optical and radiative properties of aerosols incorporating the measured chemical composition of aerosol samples collected at Patiala during October, 2011-February, 2012. Monthly average mass concentration of PM2.5, elemental carbon (EC), primary organic carbon (POC), water-soluble (WS) and insoluble (INS) aerosols ranged from 120 to 192, 6.2 to 7.2, 20 to 39, 59 to 111 and 35 to 90 μg m-3, respectively. Mass concentration of different components of aerosols was further used for the assessment of optical properties derived from Optical Properties of Aerosols and Clouds (OPAC) model simulations. Microtops based measured aerosol optical depth (AOD500) ranged from 0.47 to 0.62 showing maximum value during November and December, and minimum during February. Ångström exponent (α380-870) remained high (>0.90) throughout the study period except in February (0.74), suggesting predominance of fine mode particles over the study region. The observed ratio of scattering to absorbing aerosols was incorporated in OPAC model simulations and single scattering albedo (SSA at 500 nm) so obtained ranged between 0.80 and 0.92 with relatively low values during the period of extensive biomass burning. In the present study, SBDART based estimated values of aerosol radiative forcing (ARF) at the surface (SRF) and top of the atmosphere (TOA) ranged from -31 to -66 Wm-2 and -2 to -18 W m-2 respectively. The atmospheric ARF, ranged between + 18 and + 58 Wm-2 resulting in the atmospheric heating rate between 0.5 and 1.6 K day-1. These results signify the role of scattering and absorbing aerosols in affecting the magnitude of aerosol forcing.

  6. Solar concentrator/absorber

    NASA Technical Reports Server (NTRS)

    Von Tiesenhausen, G. F.

    1976-01-01

    Collector/energy converter, consisting of dual-slope optical concentrator and counterflow thermal energy absorber, is attached to multiaxis support structure. Efficient over wide range of illumination levels, device may be used to generate high temperature steam, serve as solar powered dryer, or power absorption cycle cooler.

  7. Laser-Induced Damage Threshold and Certification Procedures for Optical Materials

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This document provides instructions for performing laser-induced-damage-threshold tests and pass-fail certification tests on optical materials used in pulsed-laser systems. The optical materials to which these procedures apply include coated and uncoated optical substrates, laser crystals, Q-switches, polarizers, and other optical components employed in pulsed-laser systems.

  8. Physics of electromagnetic and material stresses in optical manipulation

    NASA Astrophysics Data System (ADS)

    Kemp, Brandon A.; Sheppard, Cheyenne J.

    2015-08-01

    Modeling the dynamics of optical manipulation experiments relies upon a precise mathematical representation of electromagnetic fields and the interpretation of optical momentum and stresses in materials. However, the momentum of light within media has been an issue of debate over the past century. Multiple energy-momentum models have been advanced, each, under certain conditions, agreeing with experimental observation and mathematically consistent with classical electromagnetism. The modern view is that the various formulations of electrodynamics represent different divisions of the total energy-momentum tensor, with the separation of field and matter being ambiguous. Recently, a proposed view of photon momentum identified two leading forms as the kinetic and canonical momenta. The Abraham momentum is responsible for the overall center-of-mass translation of a material, while the Minkowski momentum is responsible for translations with respect to the surrounding medium. However, the Abraham momentum corresponds to multiple, unique electromagnetic energy-momentum tensors that attempt to separate field from material responses (e.g. Abraham, Chu, and Einstein-Laub). However, only the form of the kinetic momentum density has been revealed, while the formulation that uniquely separates the kinetic stress tensor has remained ambiguous. In this correspondence, multiple formulations are considered within the framework of relativistic electrodynamics. We apply various mathematical techniques to identify the kinetic subsystem of electrodynamics. While optical manipulation is usually modeled using a stationary medium approximation, the lessons from relativistic electrodynamics reveal a specific distribution of electromagnetic stress in media. The physics of optical and static manipulation of dielectric particles are described within this framework.

  9. Optical characterization platform for transparent insulation materials in solar energy

    NASA Astrophysics Data System (ADS)

    Platzer, Werner J.

    1994-09-01

    The precise optical characterization of transparent insulation materials used in windows, flat- plate collectors or for transparent insulation of buildings, is an important step to design solar collector and daylighting systems with these materials and to estimate energy benefits, peak loads, efficiencies, and different potential risks such as overheating, thermal damage or glare. Physically the aim is clear: Angle-dependent transmittance and reflectance properties for the solar and visible wavelength ranges yield the necessary information for the engineer to enable him to design a good system. However, it is far from trivial to obtain these data with sufficient precision for the rather different materials. The class of TIMs poses mainly the following problems, originating in their special character. TIMs often: (a) have a rather coarse structure, (b) show considerable scattering, (c) are relatively thick, (d) are spectrally selective, (e) and are not always rotationally symmetric. Therefore the optical measurement process has to: (a) integrate over a relatively large sample area (b) be able to detect intensity scattered in the sample (c) take into account the complex structure of the sample (d) and weight the different spectral bands correctly. We have set-up a set of radiation sources and integrating detector spheres which are able to measure directional-hemispherical and hemispherical-hemispherical reflectance and transmittance (hence also absorptance) for the visible and the solar wavelength range. This was possible by applying a PTFE-based coating to the spheres, having a unique spectrally flat response over the whole range, and using non-selective broadband detectors. Careful design tried to optimize integrating sphere geometry. Moreover, spectral measurements between 285-1100 nm are possible with an optical multichannel analyzer utilizing glass fiber optics. The whole experimental set-up will be presented and discussed together with representative results.

  10. Inverse Algorithm Optimization for Determining Optical Properties of Biological Materials from Spatially-Resolved Diffuse Reflectance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Optical characterization of biological materials is useful in many scientific and industrial applications like biomedical diagnosis and nondestructive quality evaluation of food and agricultural products. However, accurate determination of the optical properties from intact biological materials base...

  11. Optical quantitation of absorbers in variously shaped turbid media based on the microscopic Beer-Lambert law. A new approach to optical computerized tomography.

    PubMed

    Tsuchiya, Y; Urakami, T

    1998-02-09

    To determine the concentrations of an absorber in variously shaped turbid media such as human tissue, we propose analytical expressions for diffuse re-emission in time and frequency domains, based on the microscopic Beer-Lambert law that holds true when we trace a zigzag photon path in the medium. Our expressions are implicit for the scattering properties, the volume shape, and the source-detector separation. We show that three observables are sufficient to determine the changes in the concentration and the absolute concentrations of an absorber in scattering media as long as the scattering property remains constant. The three observables are: the re-emission, the mean pathlength or group delay, and the extinction coefficient of the absorber. We also show that our equations can be extended to describe photon migration in nonuniform media. The validity of the predictions is confirmed by measuring a tissue-like phantom.

  12. Triboluminescent Materials for Smart Optical Damage Sensors for Space Applications

    NASA Technical Reports Server (NTRS)

    Aggarwal, Mohan D.; Penn, Benjamin G.; Miller, Jim

    2007-01-01

    Triboluminescence is light that is produced by pressure, friction or mechanical shock. New composite materials are constantly being reengi neered in an effort to make lightweight spacecrafts for various NASA missions. For these materials there is interest in monitoring the con dition of the composite in real time to detect any delamination or cr acking due to damage, fatigue or external forces. Methods of periodic inspection of composite structures for mechanical damage such as ult rasonic testing are rather mature. However, there is a need to develop a new technique of damage detection for composites, which could dete ct cracking or delamination from any desired location within a materi al structure in real time. This could provide a valuable tool in the confident use of composite materials for various space applications. Recently, triboluminnescent materials have been proposed as smart sen sors of structural damage. To sense the damage, these materials can b e epoxy bonded or coated in a polymer matrix or embedded in a composi te host structure. When the damage or fracture takes place in the hos t structure, it will lead to the fracture of triboluminescent crystal s resulting in a light emission. This will warn, in real time, that a structural damage has occurred. The triboluminescent emission of the candidate phosphor has to be sufficiently bright, so that the light signal reaching from the point of fracture to the detector through a fiber optic cable is sufficiently strong to be detected. There are a large number of triboluminescent materials, but few satisfy the above criterion. Authors have synthesized a Eu based organic material know n as Europium tetrakis (dibenzoylmethide) triethylammonium .(EuD(sub 4)TEA), one of the bright triboluminescent materials, which is a pote ntial candidate for application as a damage sensor and could be made into a wireless sensor with the addition of microchip, antenna and el ectronics. Preliminary results on the synthesis and

  13. Material candidates for optical frequency comb generation in microspheres.

    PubMed

    Riesen, Nicolas; Afshar V, Shahraam; François, Alexandre; Monro, Tanya M

    2015-06-01

    This paper evaluates the opportunities for using materials other than silica for optical frequency comb generation in whispering gallery mode microsphere resonators. Different materials are shown to satisfy the requirement of dispersion compensation in interesting spectral regions such as the visible or mid-infrared and for smaller microspheres. This paper also analyses the prospects of comb generation in microspheres within aqueous solution for potential use in applications such as biosensing. It is predicted that to achieve comb generation with microspheres in aqueous solution the visible low-loss wavelength window of water needs to be exploited. This is because efficient comb generation necessitates ultra-high Q-factors, which are only possible for cavities with low absorption of the evanescent field outside the cavity. This paper explores the figure of merit for nonlinear interaction efficiency and the potential for dispersion compensation at unique wavelengths for a host of microsphere materials and dimensions and in different surroundings.

  14. DNA-linked nanoparticle materials: optical, electrical, and structural properties

    NASA Astrophysics Data System (ADS)

    Lazarides, A.; Park, S.-J.; Mirkin, C.; Storhoff, J.; Schatz, G.; Brazis, P.; Kannewurf, C.

    2001-03-01

    Novel bioinorganic materials composed of Au nanoparticles linked with DNA have been developed as colorimetric DNA sensors. In the presence of complimentary DNA, particles dressed with one of two oligonucleotide sequences are linked to form binary nanoparticle aggregates. Assemblies linked at 298K have plasmon frequency shifts that decrease with increasing linker length; annealing, however, eliminates the length dependence of the shift. Neither sedimentation rate measurements nor theoretical studies of the optical properties provide unambiguous explanation. However, small-angle X-ray scattering (SAXS) measurements indicate that separations between nanoparticles with or without annealing are proportional to the number of base pairs in the oligonucleotide linkers. DNA is thus shown to offer a means for tuning separations in nanoparticle materials. We have also investigated the electrical and structural properties of dry Au nanoparticle films linked by DNA. The assemblies are semiconducting, which suggests that DNA can be used as a chemically specific scaffolding material for assembly of conductive structures.

  15. Optical Probes For Continuous Fabry-Perot Velocimetry Inside Materials

    SciTech Connect

    Goosman, D; Wade, J; Garza, R; Avara, G; Crabtree, T; Rivera, A; Hare, D; Tolar, D; Bratton, B

    2004-08-11

    We have used velocimetry for many years at LLNL to measure velocity-time histories of surfaces in dynamic experiments. We have developed and now use special instrumentation to make continuous shock-velocity measurements inside of materials. The goal is to extend the field of velocimetry into a new area of application in shock physics. At the last Congress we reported the successful use of our new filter system for selectively eliminating most of the non- Doppler-shifted light. We showed one record of a fiber embedded inside an explosive making a continuous detonation velocity-time history. At that time it was difficult to obtain complete records. We have now carried out over 65 inexpensive experiments usually using small cylinders or rectangular blocks of explosives or metals. Most were started by detonating a 25 mm diam by 25 mm long cylinder of Comp B explosive to drive a shock into an adjacent material of similar dimensions, using our embedded fiber probes. In contrast to surface velocimetry, embedded measurements involve detailed hydrodynamic considerations in order to result in a successful record. Calculations have guided us in understanding of various failed and successful experiments. The homogeneity of the explosive, poor contact, the materials used in the cladding and core of the fiber optic probes, and the shock speeds to be covered all greatly affect the success of an experiment. For example, a poor contact between the optical fiber and its environment causes severe loss of data. Non-symmetric air gaps on one side of the fiber cause 3 dimensional hydrodynamic effects which cause the shock wave in the fiber core to be too steeply angled to reflect light. We have recently developed and successfully used a special probe to usually overcome this limitation. We have custom designed several unique types of fiber-optic probes for specialty applications, using both solid and liquid core materials, to extend the usable shock-velocity range.

  16. Extreme Spectroscopy: In situ nuclear materials behavior from optical data

    SciTech Connect

    Guimbretiere, G.; Canizares, A.; Raimboux, N.; Omnee, R.; Duval, F.; Ammar, M.R.; Simon, P.; Desgranges, L.; Mohun, R.; Jegou, C.; Magnin, M.

    2015-07-01

    In the nuclear industry, materials are regularly exposed to high temperature or/and irradiation and a better knowledge and understanding of their behavior under such extreme conditions is a key-point for improvements and further developments. Nowadays, Raman spectroscopy begins to be well known as a promising technique in the post mortem and remote characterization of nuclear materials exposed to extreme conditions. On this topic, at ANIMMA 2013 conference, we have presented some results about its implementation in the study of model or real nuclear fuel. However, the strength of Raman spectroscopy as in situ characterization tool is mainly its ability to be implemented remotely through optical fibers. Aware of this, implementation of other optical techniques can be considered in order to gain information not only on the structural dynamics of materials but also on the electronic charge carrier populations. In this paper, we propose to present our last advances in Raman characterization of nuclear materials and enlarge to the in situ use of complementary optical spectroscopies. Emphasis will be made on the information that can be gained to the behavior of the model fuel depleted UO{sub 2} under extreme conditions of high temperature and ionic irradiation: - In Situ Raman identification of the radiolysis alteration products of UO{sub 2} in contact with water under ionic irradiation. - In Situ Raman recording of the damaged dynamic of UO{sub 2} under inert atmosphere. - In Situ Raman and photo-luminescence study of virgin and damaged UO2 at high temperature. - In Situ study of electronic charge carriers' behavior in U{sub x}Th{sub 1-x}O{sub 2} solid solutions by mean of Iono- and Thermo- luminescence under and post- ionic irradiation. (authors)

  17. Metrology and design of gradient-index optical materials

    NASA Astrophysics Data System (ADS)

    Lin, Di

    Gradient-index (GRIN) materials provide interesting ways to direct light propagation inside a bulk medium. Their application in optical systems as compact optical elements offer many advantages such as convenient form factor, unique dispersion characteristics, aberration correction capabilities, etc. With the recent technological advances in the fabrication techniques for these materials, it is reasonable to speculate that arbitrary refract index distributions in GRIN media can be realized in the near future. The integration of GRIN components into optical systems requires accurate knowledge of their refractive index distribution. Numerical methods for recovering the refractive index of the material using boundary value measurements of position and slope for interrogating rays that transit the medium are described. For one-dimensional index profiles, we develop a bootstrap algorithm for recovering the refractive index in successive regions of the overall profile from the boundary value data. We then compare the reconstructed index profile obtained in this method with that of a different method based on ray displacement and show good agreement in computer simulation as well as in experimental measurement. In the case of two-dimensional refractive index distributions, we show that the path integrals describing beam deflection inside the material can be cast in the form of linear algebraic equations using a simplifying assumption that decouples unknown ray trajectories inside the medium from the refractive index. The resulting linear system is inverted numerically to recover the refractive index distribution, and the ray trajectories are subsequently ascertained through an iterative ray trace procedure. Using boundary values of ray position and slope generated from a numerical ray trace, we show that this method can achieve RMS index errors less than 0.5% of the refractive index range. In addition, we explore the application of GRIN components in designing optical

  18. On-line optical sensors for industrial material inspection

    NASA Astrophysics Data System (ADS)

    Cielo, Paolo G.

    1990-08-01

    In the modem computer-integrated material processing plant statistical process control plays an increasingly important role. A corresponding need for rugged and noninvasive on-line sensors capable of reliable and unattended performance is becoming more and more urgent. Optical sensors are often being adopted for such tasks not only because of their noncontact nature implying an easy adaptability to the automated inspection of continuously moving products at any temperature but also in view of their high response speed intrinsic resolution and increasing ruggedness. Properties which may be probed with optical devices include product features such as geometrical size and shape or surface integrity as well as process parameters such as temperature speed or vibration amplitude. This paper reviews a number of optical sensors which were recently developed at our institute for industrial material online inspection. Examples include surface defect detection 3-D lumber board scanning and infrared temperature measurement either in furnace or during spray deposition. The emphasis is on noncontact techniques well suited to automation and specifically adapted to each particular application with minimum perturbation of the industrial process. 1.

  19. Triboluminescent Materials for Smart Optical Damage Sensors for Space Applications

    NASA Technical Reports Server (NTRS)

    Aggarwal, M. D.; Penn, B. G.; Miller, J.; Sadate, S.; Batra, A. K.

    2008-01-01

    There is a need to develop a new technique of damage detection for composites, which could detect cracking or delamination from any desired location within a material structure in real time. Recently, triboluminescent materials have been proposed as smart sensors of structural damage. To sense the damage, these materials can be epoxy bonded, coated in a polymer matrix, or embedded in a composite host structure. When the damage or fracture takes place in the host structure, the resultant fracture of triboluminescent crystals creates a light emission. This will warn in real time that structural damage has occurred. The triboluminescent emission of the candidate phosphor has to be bright enough that the light reaching from the point of fracture to the detector through a fiber optic cable is detectable. There are a large number of triboluminescent materials, but few satisfy the above criterion. The authors have synthesized an organic material known as Europium tetrakis (dibenzoylmethide) triethylammonium (EuD4TEA), which is a potential candidate for application as a damage sensor and could be made into a wireless sensor with the addition of microchip, antenna, and electronics. Preliminary results on the synthesis and characterization of this material are presented.

  20. Research on lunar materials. [optical, chemical, and electrical properties

    NASA Technical Reports Server (NTRS)

    Gold, T.

    1978-01-01

    Abstracts of 14 research reports relating to investigations of lunar samples are presented. The principal topics covered include: (1) optical properties of surface and core samples; (2) chemical composition of the surface layers of lunar grains: Auger electron spectroscopy of lunar soil and ground rock samples; (3) high frequency electrical properties of lunar soil and rock samples and their relevance for the interpretation of lunar radar observations; (4) the electrostatic dust transport process; (5) secondary electron emission characteristics of lunar soil samples and their relevance to the dust transportation process; (6) grain size distribution in surface soil and core samples; and (7) the optical and chemical effects of simulated solar wind (2keV proton and a particle radiation) on lunar material.

  1. Enhanced optical limiting effects of graphene materials in polyimide

    SciTech Connect

    Gan, Yao; Feng, Miao; Zhan, Hongbing

    2014-04-28

    Three different graphene nanostructure suspensions of graphene oxide nanosheets (GONSs), graphene oxide nanoribbons (GONRs), and graphene oxide quantum dots (GOQDs) are prepared and characterized. Using a typical two-step method, the GONSs, GONRs, and GOQDs are incorporated into a polyimide (PI) matrix to synthesize graphene/PI composite films, whose nonlinear optical (NLO) and optical limiting (OL) properties are investigated at 532 nm in the nanosecond regime. The GONR suspension exhibits superior NLO and OL effects compared with those of GONSs and GOQDs because of its stronger nonlinear scattering and excited-state absorption. The graphene/PI composite films exhibit NLO and OL performance superior to that of their corresponding suspensions, which is attributed primarily to a combination of nonlinear mechanisms, charge transfer between graphene materials and PI, and the matrix effect.

  2. Phantom materials mimicking the optical properties in the near infrared range for non-invasive fetal pulse oximetry.

    PubMed

    Ley, Sebastian; Stadthalter, Miriam; Link, Dietmar; Laqua, Daniel; Husar, Peter

    2014-01-01

    An optical phantom of the maternal abdomen during pregnancy is an appropriate test environment to evaluate a non-invasive system for fetal pulse oximetry. To recreate the optical properties of maternal tissue, fetal tissue and blood suitable substitutes are required. For this purpose, phantom materials are used, which consist of transparent silicone or water as host material. Cosmetic powder and India ink are investigated as absorbing materials, whereas titanium dioxide particles are examined as scattering medium. Transmittance and reflectance measurements of the samples were performed in the spectral range from 600 nm to 900 nm using integrating sphere technique. The scattering and absorption coefficients and the anisotropy factor were determined using Kubelka-Munk theory. The results were used to compute the required mixture ratios of the respective components to replicate the optical properties of maternal tissue, fetal tissue and blood, and corresponding samples were produced. Their optical properties were investigated in the same manner as mentioned above. The results conform to the values of various types of tissues and blood given in the scientific literature.

  3. Cellulose-silver nanoparticle hybrid materials to control spoilage-related microflora in absorbent pads located in trays of fresh-cut melon.

    PubMed

    Fernández, Avelina; Picouet, Pierre; Lloret, Elsa

    2010-08-15

    The antimicrobial activity of newly developed cellulose-silver nanoparticle hybrid materials was investigated during storage of minimally processed "Piel de Sapo" melon. Silver nanoparticles were produced after in-situ reduction by physical methods of 1% silver nitrate adsorbed on cellulose fibres; they accounted between 5 and 35 nm diameter, and were not aggregated. Fresh-cut melon pieces were stored for 10 days at 4 degrees C under natural modified atmosphere packaging, in presence or absence of silver loaded absorbent pads. The evolution of headspace gas composition, quality parameters, and the antimicrobial activity against spoilage-related microorganisms were investigated. The cellulose-silver nanoparticle hybrid materials released silver ions after melon juice impregnated the pad. The released silver ions were particularly useful to control the population of spoilage-related microorganisms in cellulose based absorbent pads in contact with vegetable matrices, showing a low chelating effect against silver ions; the lag phases of the microorganisms were considerably incremented and microbial loads in the pads remained in average approx. 3 log(10) CFU/g below the control during the investigated storage period. Furthermore, the presence of silver loaded absorbent pads retarded the senescence of the melon cuts, presenting remarkably lower yeast counts, lower degrees Brix values, and a juicier appearance after 10 days of storage.

  4. Trace Impurities and Radiation Defects in Optical Materials

    NASA Astrophysics Data System (ADS)

    Malovichko, Galina; Grachev, Valentin; Meyer, Martin; Munro, Mark; Pankratov, Vladimir

    2007-05-01

    Trace impurities and radiation defects lead to inevitable performance degradation of devices based on optical materials. The results of the Electron Paramagnetic Resonance (EPR) study of defects in as grown and irradiated single crystals are reported. Among investigated optical materials are LiNbO3, Li2B4O7, KTiOPO4 etc. Crystals from different vendors or grown by different ways have different concentrations of non-controlled impurities and, as a result, different physical properties, including radiation resistance. Intrinsic defects (vacancies and antisites), usually present in congruent non-stoichiometric crystals like lithium niobate and tantalate. Many EPR lines of non-controlled impurities were found in KTiOPO4 crystals. We found that dominating types of defects formed under visible, UV and gamma photon irradiation are centers created by defects trapped electron or hole. The neutron and high energy electron irradiation creates stable Frenkel pairs - interstitial ions and vacancies. Computer simulation of observed spectra allowed us to determine spectroscopic characteristics and models for more than dozen trace impurities and radiation defects. Obtained data about atomic defects can be used for a selection of materials suitable for various applications. To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.NWS07.B1.2

  5. Laser induced damage in optical materials: 8th ASTM symposium.

    PubMed

    Glass, A J; Guenther, A H

    1977-05-01

    The Eighth Annual Symposium on Optical Materials for High Power Lasers (Boulder Damage Symposium) was hosted by the National Bureau of Standards in Boulder, Colorado, from 13 to 15 July 1976. The Symposium was held under the auspices of ASTM Committee F-1, Subcommittee on Laser Standards, with the joint sponsorship of NBS, the Defense Advanced Research Project Agency, the Energy Research and Development Administration, and the Office of Naval Research. About 160 scientists attended the Symposium, including representatives of the United Kingdom, France, Canada, and Brazil. The Symposium was divided into five half-day sessions concerning Bulk Material Properties and Thermal Behavior, Mirrors and Surfaces, Thin Film Properties, Thin Film Damage, and Scaling Laws and Fundamental Mechanisms. As in previous years, the emphasis of the papers presented at the Symposium was directed toward new frontiers and new developments. Particular emphasis was given to new materials for use at 10.6 microm in mirror substrates, windo s, and coatings. New techniques in film deposition and advances in diamond-turning of optics were described. The scaling of damage thresholds with pulse duration, focal area, and wavelength were discussed. Alexander J. Glass of Lawrence Livermore Laboratory and Arthur H. Guenther of the Air Force Weapons Laboratory were co-chairpersons of the Symposium. The Ninth Annual Symposium is scheduled for 4-6 October 1977 at the National Bureau of Standards, Boulder, Colorado.

  6. Laser induced damage in optical materials: tenth ASTM symposium.

    PubMed

    Glass, A J; Guenther, A H

    1979-07-01

    The tenth annual Symposium on Optical Materials for High Power Lasers (Boulder Damage Symposium) was held at the National Bureau of Standards in Boulder, Colorado, 12-14 September 1978. The symposium was held under the auspices of ASTM Committee F-1, Subcommittee on Laser Standards, with the joint sponsorship of NBS, the Defense Advanced Research Project Agency, the Department of Energy, and the Office of Naval Research. About 175 scientists attended, including representatives of the United Kingdom, France, Canada, Japan, West Germany, and the Soviet Union. The symposium was divided into sessions concerning the measurement of absorption characteristics, bulk material properties, mirrors and surfaces, thin film damage, coating materials and design, and breakdown phenomena. As in previous years, the emphasis of the papers presented was directed toward new frontiers and new developments. Particular emphasis was given to materials for use from 10.6 microm to the UV region. Highlights included surface characterization, thin film-substrate boundaries, and advances in fundamental laser-matter threshold interactions and mechanisms. The scaling of damage thresholds with pulse duration, focal area, and wavelength was also discussed. In commemoration of the tenth symposium in this series, a number of comprehensive review papers were presented to assess the state of the art in various facets of laser induced damage in optical materials. Alexander J. Glass of Lawrence Livermore Laboratory and Arthur H. Guenther of the Air Force Weapons Laboratory were co-chairpersons. The eleventh annual symposium is scheduled for 30-31 October 1979 at the National Bureau of Standards, Boulder, Colorado.

  7. Optical properties of polymer/chalcogenide glass composite materials

    NASA Astrophysics Data System (ADS)

    Bormashenko, Edward; Pogreb, Roman; Sutovski, Semion

    2000-06-01

    The novel composite material based on middle density polyethylene on one hand and thermoplastic chalcogenide glass on other hand has been worked out. Both materials used in the research are highly transparent in the middle and far IR but refraction indexes of components differ dramatically. The basic materials, polymer and glass, have close viscosities at the temperature of polyethylene processing. This fact allowed use of the extrusion technique for homogenization purposes. We proved, that the controlled structure of a composite could be derived through the varying of technological parameters of the mixing process. Single- and twin screw extrusion processes obtained compositions, which contain up to 50% particles of chalcogenide glass, which were dispersed in the polymer matrix. The highly homogeneous compositions that contain perfect spherical glass particles of 1-2 micrometers in diameter dispersed into polymer matrix were obtained as well. Highly oriented structures involving chalcogenide glass fibers immersed in the polymer matrix were prepared under high stretch speeds as well. Such fiberlike structures exhibited pronounced polarization properties. We studied the optical properties of the composite and came to the conclusion that the controlled structure of the composite allows variation in its optical properties. It was established that it is possible to produce a composite that is opaque in the visible and near IR, and highly transparent in the 2-25-micrometers wave length band. Light scattering on oriented and disordered structures was studied by the IR spectro-goniometer. The novel composite which was developed by our group is intended for various IR-optics applications.

  8. Use of absorbent materials in on-line coupled reversed-phase liquid chromatography-gas chromatography via the through oven transfer adsorption desorption interface.

    PubMed

    Flores, Gema; Díaz-Plaza, Eva María; Cortés, Jose Manuel; Villén, Jesús; Herraiz, Marta

    2008-11-21

    The use of absorbents as retaining materials in the through oven transfer adsorption desorption interface (TOTAD) of an on-line coupled reversed-phase liquid chromatography-gas chromatography system (RPLC-GC) is proposed for the first time. A comparative study of an adsorbent (Tenax TA) and two absorbents, namely polydimethylsiloxane and poly(50% phenyl/50% methylsiloxane) is performed to establish the best experimental conditions for the automated and simultaneous determination of 15 organophosphorus and organochlorine pesticide residues in olive oil. The proposed method provides satisfactory repeatability (RSDs lower, in general, than 8.5%) and sensitivity (limits of detection ranging from 0.6 to 81.9 microg/L) for the investigated compounds.

  9. Electrochromic material and electro-optical device using same

    DOEpatents

    Cogan, Stuart F.; Rauh, R. David

    1992-01-01

    An oxidatively coloring electrochromic layer of composition M.sub.y CrO.sub.2+x (0.33.ltoreq.y.ltoreq.2.0 and x.ltoreq.2) where M=Li, Na or K with improved transmittance modulation, improved thermal and environmental stability, and improved resistance to degradation in organic liquid and polymeric electrolytes. The M.sub.y CrO.sub.2+x provides complementary optical modulation to cathodically coloring materials in thin-film electrochromic glazings and electrochromic devices employing polymeric Li.sup.+ ion conductors.

  10. Electrochromic material and electro-optical device using same

    DOEpatents

    Cogan, S.F.; Rauh, R.D.

    1992-01-14

    An oxidatively coloring electrochromic layer of composition M[sub y]CrO[sub 2+x] (0.33[le]y[le]2.0 and x[le]2) where M=Li, Na or K with improved transmittance modulation, improved thermal and environmental stability, and improved resistance to degradation in organic liquid and polymeric electrolytes. The M[sub y]CrO[sub 2+x] provides complementary optical modulation to cathodically coloring materials in thin-film electrochromic glazings and electrochromic devices employing polymeric Li[sup +] ion conductors. 12 figs.

  11. Helmholtz solitons in power-law optical materials

    SciTech Connect

    Christian, J. M.; McDonald, G. S.; Potton, R. J.; Chamorro-Posada, P.

    2007-09-15

    A nonlinear Helmholtz equation for optical materials with regimes of power-law type of nonlinearity is proposed. This model captures the evolution of broad beams at any angle with respect to the reference direction in a wide range of media, including some semiconductors, doped glasses, and liquid crystals. Exact analytical soliton solutions are presented for a generic nonlinearity, within which known Kerr solitons comprise a subset. Three general conservation laws are also reported. Analysis and numerical simulations examine the stability of the Helmholtz power-law solitons. A propagation feature, associated with spatial solitons in power-law media, constituting a class of oscillatory solution, is identified.

  12. Optical method for determining the mechanical properties of a material

    DOEpatents

    Maris, H.J.; Stoner, R.J.

    1998-12-01

    Disclosed is a method for characterizing a sample, comprising the steps of: (a) acquiring data from the sample using at least one probe beam wavelength to measure, for times less than a few nanoseconds, a change in the reflectivity of the sample induced by a pump beam; (b) analyzing the data to determine at least one material property by comparing a background signal component of the data with data obtained for a similar delay time range from one or more samples prepared under conditions known to give rise to certain physical and chemical material properties; and (c) analyzing a component of the measured time dependent reflectivity caused by ultrasonic waves generated by the pump beam using the at least one determined material property. The first step of analyzing may include a step of interpolating between reference samples to obtain an intermediate set of material properties. The material properties may include sound velocity, density, and optical constants. In one embodiment, only a correlation is made with the background signal, and at least one of the structural phase, grain orientation, and stoichiometry is determined. 14 figs.

  13. Emergency Optically Stimulated Luminescence Dosimetry Using Different Materials

    PubMed Central

    Sholom, S; DeWitt, R; Simon, SL; Bouville, A; McKeever, SWS

    2011-01-01

    Several materials were tested as possible individual emergency dosimeters using Optically Stimulated Luminescence (OSL) as means to assess the exposure. Materials investigated included human nails, business cards and plastic buttons. The OSL properties of these materials were studied in comparison with those of teeth. Most samples revealed OSL signals only after exposure to ionizing radiation; some samples of business cards, however, displayed a strong initial “native” signal (i.e. existing in the samples prior to irradiation). The sensitivity (minimum measurable dose) of the samples was found to vary significantly from sample to sample of the same material and was in the range from several tens of mGy to a few dozens of Gy. The dose response curves were linear for doses below 10 Gy. Fading of the OSL signals was estimated for different lenghts of times and found to be ~95%, 45%, 30% and 15% for samples of teeth, business cards, buttons and nails, respectively, following storage at room temperature in the dark for a period of 3 weeks after exposure. For samples stored under routine laboratory light, fading was much faster and the radiation-induced signals almost disappeared after a few hours of such illumination. It was concluded that the tested materials could be used in triage situations to detect and estimate the possible overexposure of individuals if the measurements can be performed soon enough after exposure. PMID:22125409

  14. Optical method for determining the mechanical properties of a material

    DOEpatents

    Maris, Humphrey J.; Stoner, Robert J.

    1998-01-01

    Disclosed is a method for characterizing a sample, comprising the steps of: (a) acquiring data from the sample using at least one probe beam wavelength to measure, for times less than a few nanoseconds, a change in the reflectivity of the sample induced by a pump beam; (b) analyzing the data to determine at least one material property by comparing a background signal component of the data with data obtained for a similar delay time range from one or more samples prepared under conditions known to give rise to certain physical and chemical material properties; and (c) analyzing a component of the measured time dependent reflectivity caused by ultrasonic waves generated by the pump beam using the at least one determined material property. The first step of analyzing may include a step of interpolating between reference samples to obtain an intermediate set of material properties. The material properties may include sound velocity, density, and optical constants. In one embodiment, only a correlation is made with the background signal, and at least one of the structural phase, grain orientation, and stoichiometry is determined.

  15. Optical fiber sensors for damage analysis in aerospace materials

    NASA Technical Reports Server (NTRS)

    Schindler, Paul; May, Russell; Claus, Richard

    1995-01-01

    Under this grant, fiber optic sensors were investigated for use in the nondestructive evaluation of aging aircraft. Specifically, optical fiber sensors for detection and location of impacts on a surface, and for detection of corrosion in metals were developed. The use of neural networks was investigated for determining impact location by processing the output of a network of fiberoptic strain sensors distributed on a surface. This approach employs triangulation to determine location by comparing the arrival times at several sensors, of the acoustic signal generated by the impact. For this study, a neural network simulator running on a personal computer was used to train a network using a back-propagation algorithm. Fiber optic extrinsic Fabry-Perot interferometer (EFPI) strain sensors are attached to or embedded in the surface, so that stress waves emanating from an impact can be detected. The ability of the network to determine impact location by time-or-arrival of acoustic signals was assessed by comparing network outputs with actual experimental results using impacts on a panel instrumented with optical fiber sensors. Using the neural network to process the sensor outputs, the impact location can be inferred to centimeter range accuracy directly from the arrival time data. In addition, the network can be trained to determine impact location, regardless of material anisotropy. Results demonstrate that a back-propagation network identifies impact location for an anisotropic graphite/bismaleimide plate with the same accuracy as that for an isotropic aluminum plate. Two different approaches were investigated for the development of fiber optic sensors for corrosion detection in metals, both utilizing optical fiber sensors with metal coatings. In the first approach, an extrinsic Fabry-Perot interferometric fiber optic strain sensor was placed under tensile stress, and while in the resulting strained position, a thick coating of metal was applied. Due to an increase in

  16. A soft x-ray beamline capable of canceling the performance impairment due to power absorbed on its optical elements.

    PubMed

    Reininger, Ruben; Kriesel, Ken; Hulbert, S L; Sánchez-Hanke, Cecilia; Arena, D A

    2008-03-01

    We present an entrance slitless beamline design capable of maintaining its very high performance in terms of energy resolution (>10(4)) and spot size (4x4 microm2) at the sample position despite being exposed to more than 2.15 kW of undulator radiation and a maximum power density on the optics of more than 0.9 W/mm2. Ray tracing simulations of this beamline under the worst-case thermal deformations of the optical element surfaces verify that appropriate focusing corrections are able to cancel the deleterious effects of these deformations. One of the necessary conditions for this cancellation is to illuminate the optical elements with a larger solid angle than the undulator's central cone, which contains the usable photons but is considerably smaller than the angular power distribution.

  17. Electronic structures and optical properties of α-Fe2O3-xSex alloys for solar absorber

    NASA Astrophysics Data System (ADS)

    Xia, Congxin; Jia, Yu; Zhang, Qiming

    2015-05-01

    The band structures and optical properties of α-Fe2O3-xSex alloys are studied by means of first-principles methods, considering different Se contents x. Numerical results show that Se content has an obvious influence on band structures and optical properties of α-Fe2O3-xSex alloys. The band gap values of α-Fe2O3-xSex alloys decrease monotonically when Se concentrations increase, resulting in an obvious increase of the optical absorption edge in the visible range. In particular, our results show that α-Fe2O3-xSex alloys have the direct band gap properties with band gap values when Se content x ≈ 0.17, which is beneficial to solar cell applications.

  18. Optically transparent polyelectrolyte-silica composite materials: Preparation, characterization, and application in optical chemical sensing

    SciTech Connect

    Shi, Yining; Seliskar, C.J.

    1997-03-01

    A series of polyelectrolyte-containing silica composite materials have been prepared by sol-gel processing. These optically transparent composites have been characterized by scanning electron microscopy and UV-visible spectrophotometry. These materials can be processed into monolithic disks and thin films. The thicknesses of spin-coated films of these materials on glass can be varied from 0.13 to 3.5 {mu}m as determined by an optical interferences method. These materials are ion exchangeable and less brittle than the parent silica glass due to the incorporation of the organic polyelectrolyte. These new composites retain the nanoscale porosity and optical transparency into the ultraviolet of the parent silica sol-gel glasses, making them attractive host matrixes for the immobilization of ionizable dye molecules and chemical reagents. An optical pH sensing platform (0.9 x 2.5 cm) based on the electrostatic immobilization of HPTS (8-hydroxy-1,3,6-pyrenetrisulfonic acid trisodium salt) in a PDMDAAC (poly(diallyldimethylammonium chloride))-silica composite film was fabricated and evaluated. The results clearly demonstrate that this platform is easy to construct with high batch reproducibility and can be regenerated by simple solution ion exchange. The platform is usable in both the modes of absorption and fluorescence, making it versatile. Having a fast response time (ca. {approximately}2 s to more than 2 units of pH change), the platform is also highly resistant to dye leaching and storage degradation over a period of months. 49 refs., 9 figs., 2 tabs.

  19. Micro-optical elements and optical materials of certain spider webs

    NASA Astrophysics Data System (ADS)

    Kane, D. M.; Naidoo, N.; Little, D. J.

    2012-06-01

    Certain spider webs are composed of several types of micro-optical elements made from transparent optical materials. The silks (radial and capture) are almost exclusively protein. The nearly cylindrical silks have diameters in the range 0.1 to several microns and cross-sectional morphology that is cylindrical-multi-layered,.as studied by transmission electron microscopy, The capture threads are coated with aqueous adhesive that also forms into nearly elliptical micro-lenses (adhesive droplets) mounted on the near cylindrical silks. The remaining elements of the web are the cement junctions tying the radial and the capture threads of the web together. These are irregularly shaped platelets. Progress to date on our research characterizing the optical properties and function of these transparent orb webs has been to interpret the reflection and transmission properties of the elements of the web, and the web as a whole, in natural lighting; to evaluate the optical finish of the surface of the silks and capture droplets; and to measure the principal refractive indices of radial silks using new immersion based methods developed for application to micron-sized, curved optical elements. Here we report the principal refractive indices, birefringence, dispersion and morphology of transparent spider silk subject to various chemical treatments. The morphology is measured using TEM. Insight into the physical origin of the refractive index properties will be discussed.

  20. Sound Absorbers

    NASA Astrophysics Data System (ADS)

    Fuchs, H. V.; Möser, M.

    Sound absorption indicates the transformation of sound energy into heat. It is, for instance, employed to design the acoustics in rooms. The noise emitted by machinery and plants shall be reduced before arriving at a workplace; auditoria such as lecture rooms or concert halls require a certain reverberation time. Such design goals are realised by installing absorbing components at the walls with well-defined absorption characteristics, which are adjusted for corresponding demands. Sound absorbers also play an important role in acoustic capsules, ducts and screens to avoid sound immission from noise intensive environments into the neighbourhood.

  1. Organometallic acetylides of Pt(II), Au(I) and Hg(II) as new generation optical power limiting materials.

    PubMed

    Zhou, Gui-Jiang; Wong, Wai-Yeung

    2011-05-01

    Within the scope of nonlinear optics, optical power limiting (OPL) materials are commonly regarded as an important class of compounds which can protect the delicate optical sensors or human eyes from sudden exposure to damaging intense laser beams. Recent efforts have been devoted to developing organometallic acetylide complexes, dendrimers and polymers as high performance OPL materials of the next generation which can favorably optimize the optical limiting/transparency trade-off issue. These metallated materials offer a new avenue towards a new family of highly transparent homo- and heterometallic optical limiters with good solution processability which outperform those of current state-of-the-art visible-light-absorbing competitors such as fullerenes, metalloporphyrins and metallophthalocyanines. This critical review aims to provide a detailed account on the recent advances of these novel OPL chromophores. Their OPL activity was shown to depend strongly on the electronic characters of the aryleneethynylene ligand and transition metal moieties as well as the conjugation chain length of the compounds. Strategies including copolymerization with other transition metals, change of structural geometry, use of a dendritic platform and variation of the type and content of transition metal ions would strongly govern their photophysical behavior and improve the resulting OPL responses. Special emphasis is placed on the structure-OPL response relationships of these organometallic acetylide materials. The research endeavors for realizing practical OPL devices based on these materials have also been presented. This article concludes with perspectives on the current status of the field, as well as opportunities that lie just beyond its frontier (106 references).

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

    NASA Astrophysics Data System (ADS)

    Reitzig, Manuela; Härtling, Thomas; Opitz, Jörg

    2014-03-01

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

  3. Electro-optic materials by solid source MOCVD

    SciTech Connect

    Hiskes, R.; Dicarolis, S.A.; Fouquet, J.; Lu, Z.; Feigelson, R.S.; Route, R.K.; Leplingard, F.; Foster, C.M.

    1993-12-01

    The solid source MOCVD technique, employing a single powder vaporization source composed of mixed beta-diketonate metalorganic compounds, has been used to grow thin films of a variety of electro-optic materials, including lithium niobate, strontium barium niobate, and potassium niobate. Preliminary results for potassium niobate films indicate that a volatile potassium organometallic source can be synthesized useful for growing potassium niobate by MOCVD. High single phase (001) oriented strontium barium niobate films have been deposited which exhibit waveguiding behavior. The most extensive work has been done on lithium niobate deposited epitaxially on a variety of substrates. Oriented z-axis (001) films have been grown on c-axis sapphire with and without a (111) oriented platinum base electrode and on a bulk grown lithium niobate substrate. Films grown directly on c-axis sapphire at 700 C exhibit x-ray rocking curve linewidths as low as .044 degrees, nearly perfect in-plane orientation as determined by x-ray phi scans, and peak-to-peak surface roughness less than 40 {Angstrom}. Optical waveguiding has been demonstrated by single prism coupling technique on similar films 1175--2000 {Angstrom} thick grown at 500 C, with optical losses of approximately 2 db/cm at 632.8 nm measured over 3.5 cm long films. Polarization vs. electric field measurements on 1100 {Angstrom} thick films grown on platinum show a hysteresis loop indicating ferroelectric behavior.

  4. Mode-specific study of nanoparticle-mediated optical interactions in an absorber/metal thin film system

    NASA Astrophysics Data System (ADS)

    Yu, Binxing; Woo, Joseph; Kong, Michael; O'Carroll, Deirdre M.

    2015-07-01

    We present an experimental and theoretical study of the electromagnetic interaction between a single gold nanoparticle and a thin gold substrate separated by a sub-50 nm-thick optically absorptive polythiophene spacer layer. Single-particle dark-field scattering spectra show distinct resonance features assigned to four different modes: a horizontal image dipole coupling mode, a vertical image dipole coupling mode and horizontal and vertical coupling modes between localized surface plasmon resonances (LSPRs) and surface plasmon polaritons (SPPs). Relatively broadband spectral tuning of the modes can be achieved by modification of the thickness of either the absorptive spacer or the underlying metal film. Dark-field images also reveal the existence of particles for which the signal of the horizontal image dipole coupling mode is suppressed. This is attributed to partial-embedding of gold nanoparticles into the polythiophene spacer and leads to higher scattered light intensities at longer wavelengths. Full-field electromagnetic simulations show good agreement with the experimental results for the various sample conditions. Strong local electric field confinement at longer wavelengths in the polythiophene spacer, due to the vertical image dipole coupling mode and a LSPR-SPP coupling mode, is also observed in simulations and contributes to absorption enhancement in the spacer. Furthermore, we find absorption enhancement in the semiconducting polythiophene spacer increases with decreasing thickness, indicating the increased light trapping ability of the gold nanoparticles for ultra-thin semiconductor layers. The need for ever-thinner semiconductor layers in optoelectronic devices requires effective light trapping at deeply-subwavelength scales. This work demonstrates that light trapping in sub-50 nm-thick semiconductor layers is possible using a ``sphere-on-plane'' system and offers insight into how coupling modes can be manipulated in this system.We present an

  5. New Optical Sensing Materials for Application in Marine Research

    NASA Astrophysics Data System (ADS)

    Borisov, S.; Klimant, I.

    2012-04-01

    Optical chemosensors are versatile analytical tools which find application in numerous fields of science and technology. They proved to be a promising alternative to electrochemical methods and are applied increasingly often in marine research. However, not all state-of-the- art optical chemosensors are suitable for these demanding applications since they do not fully fulfil the requirements of high luminescence brightness, high chemical- and photochemical stability or their spectral properties are not adequate. Therefore, development of new advanced sensing materials is still of utmost importance. Here we present a set of novel optical sensing materials recently developed in the Institute of Analytical Chemistry and Food Chemistry which are optimized for marine applications. Particularly, we present new NIR indicators and sensors for oxygen and pH which feature high brightness and low level of autofluorescence. The oxygen sensors rely on highly photostable metal complexes of benzoporphyrins and azabenzoporphyrins and enable several important applications such as simultaneous monitoring of oxygen and chlorophyll or ultra-fast oxygen monitoring (Eddy correlation). We also developed ulta-sensitive oxygen optodes which enable monitoring in nM range and are primary designed for investigation of oxygen minimum zones. The dynamic range of our new NIR pH indicators based on aza-BODIPY dyes is optimized for the marine environment. A highly sensitive NIR luminescent phosphor (chromium(III) doped yttrium aluminium borate) can be used for non-invasive temperature measurements. Notably, the oxygen, pH sensors and temperature sensors are fully compatible with the commercially available fiber-optic readers (Firesting from PyroScience). An optical CO2 sensor for marine applications employs novel diketopyrrolopyrrol indicators and enables ratiometric imaging using a CCD camera. Oxygen, pH and temperature sensors suitable for lifetime and ratiometric imaging of analytes

  6. Synthesis and Characterization of Novel Nonlinear Optical Materials

    NASA Astrophysics Data System (ADS)

    Liang, Cheryl Shuang

    1992-01-01

    Nonlinear optic materials are becoming increasingly important because of their many technological applications, such as second harmonic generation (SHG), optical switching, and waveguides for optical transmission. Currently, there is a demand for crystals transparent in the UV region, which would make the third and higher harmonic generations feasible. Compounds with the general stoichiometry ABCO _4 structural systems have shown to be promising candidates for frequency doubling into the UV region. The stuffed tridymite structure in which these ABCO_4 compounds crystallize is very tolerant to substitution, and over two hundred compounds have been synthesized up to date. While the presently available theories of optical nonlinearity have been applied to many inorganic solids, the threatened structure theory applied for ferroelectric properties can also be used to describe the structure/property relationship in the ABCO_4 structural family. Compounds synthesized for this study, ALiPO_4 (A = Sr, Ba, Pb) have shown that the SHG of these materials can be maximized by bringing each system close to its structural phase transition or by inducing stress in the pure phase structure. Studies have shown that the dielectric coefficients of KNbO_3 increase by more than tenfold with tantalum doping. This prompted the investigation of a mixed niobium/tantalum containing channelled tetrahedra/octahedra open framework, K_{2/3}Li _{1/3}Nb_ {rm 2-x}Ta_{ rm x}PO_8. These compounds are capable of ion exchange, where other cations are used to replace potassium. The cation-framework interaction mimics the guest-host relationship characteristic of many traditional zeolitic materials. This interaction also enables us to determine the role of the cation in framework polarizability, which can be measured by SHG intensities. Through ion exchange, many isostructural compounds can be made at low temperatures. A family of layered rubidium niobium/tantalum oxide compounds have been synthesized in

  7. Growth of bulk single crystals of organic materials for nonlinear optical devices - An overview

    NASA Technical Reports Server (NTRS)

    Penn, Benjamin G.; Cardelino, Beatriz H.; Moore, Craig E.; Shields, Angela W.; Frazier, D. O.

    1991-01-01

    Highly perfect single crystals of nonlinear optical organic materials are required for use in optical devices. An overview of the bulk crystal growth of these materials by melt, vapor, and solution processes is presented. Additionally, methods that may be used to purify starting materials, detect impurities at low levels, screen materials for crystal growth, and process grown crystals are discussed.

  8. Polymeric variable optical attenuators based on magnetic sensitive stimuli materials

    NASA Astrophysics Data System (ADS)

    de Pedro, S.; Cadarso, V. J.; Ackermann, T. N.; Muñoz-Berbel, X.; Plaza, J. A.; Brugger, J.; Büttgenbach, S.; Llobera, A.

    2014-12-01

    Magnetically-actuable, polymer-based variable optical attenuators (VOA) are presented in this paper. The design comprises a cantilever which also plays the role of a waveguide and the input/output alignment elements for simple alignment, yet still rendering an efficient coupling. Magnetic properties have been conferred to these micro-opto-electromechanical systems (MOEMS) by implementing two different strategies: in the first case, a magnetic sensitive stimuli material (M-SSM) is obtained by a combination of polydimethylsiloxane (PDMS) and ferrofluid (FF) in ratios between 14.9 wt % and 29.9 wt %. An M-SSM strip under the waveguide-cantilever, defined with soft lithography (SLT), provides the required actuation capability. In the second case, specific volumes of FF are dispensed at the end of the cantilever tip (outside the waveguide) by means of inkjet printing (IJP), obtaining the required magnetic response while holding the optical transparency of the waveguide-cantilever. In the absence of a magnetic field, the waveguide-cantilever is aligned with the output fiber optics and thus the intrinsic optical losses can be obtained. Numerical simulations, validated experimentally, have shown that, for any cantilever length, the VOAs defined by IJP present lower intrinsic optical losses than their SLT counterparts. Under an applied magnetic field (Bapp), both VOA configurations experience a misalignment between the waveguide-cantilever and the output fiber optics. Thus, the proposed VOAs modulate the output power as a function of the cantilever displacement, which is proportional to Bapp. The experimental results for the three different waveguide-cantilever lengths and six different FF concentrations (three per technology) show maximum deflections of 220 µm at 29.9 wt % of FF for VOASLT and 250 µm at 22.3 wt % FF for VOAIJP, at 0.57 kG for both. These deflections provide maximum actuation losses of 16.1 dB and 18.9 dB for the VOASLT and VOAIJP

  9. Nonlinear optics and carrier dynamics in nanostructured and two-dimensional materials

    NASA Astrophysics Data System (ADS)

    Suess, Ryan J.

    significant role. Probing the graphene at intermediate photon energies enables the investigation of the nonlinear optical properties in the graphene as its electron system is heated by the intense pump pulse. By simultaneously measuring the reflected and transmitted terahertz light, a precise determination of the pump-induced change in absorption can be made. We observe that as the intensity of the terahertz radiation is increased, the optical properties of the graphene change from interband, semiconductor-like absorption, to a more metallic behavior with increased intraband processes. This transition reveals itself in our measurements as an increase in the terahertz transmission through the graphene at low fluence, followed by a decrease in transmission and the onset of a large, photo-induced reflection as fluence is increased. A hybrid optical-thermodynamic model successfully describes our observations and predicts this transition will persist across mid- and far-infrared frequencies. This study further demonstrates the important role that reflection plays since the absorption saturation intensity (an important figure of merit for graphene-based saturable absorbers) can be underestimated if only the transmitted light is considered. These findings are expected to contribute to the development of new optoelectronic devices designed to operate in the mid- and far-infrared frequency range. Lastly we discuss recent work with black phosphorus, a two-dimensional material that has recently attracted interest due to its high mobility and direct, configurable band gap (300 meV to 2eV), depending on the number of atomic layers comprising the sample. In this work we examine the pump-induced change in optical transmission of mechanically exfoliated black phosphorus flakes using a two-color optical pump-probe measurement. The time-resolved data reveal a fast pump-induced transparency accompanied by a slower absorption that we attribute to Pauli blocking and free-carrier absorption

  10. Unidirectional perfect absorber

    PubMed Central

    Jin, L.; Wang, P.; Song, Z.

    2016-01-01

    This study proposes a unidirectional perfect absorber (UPA), which we realized with a two-arm Aharonov-Bohm interferometer, that consists of a dissipative resonator side-coupled to a uniform resonator array. The UPA has reflection-less full absorption on one direction, and reflectionless full transmission on the other, with an appropriate magnetic flux and coupling, detuning, and loss of the side-coupled resonator. The magnetic flux controls the transmission, the left transmission is larger for magnetic flux less than one-half flux quantum; and the right transmission is larger for magnetic flux between one-half and one flux quantum. Besides, a perfect absorber (PA) can be realized based on the UPA, in which light waves from both sides, with arbitrary superposition of the ampli- tude and phase, are perfectly absorbed. The UPA is expected to be useful in the design of novel optical devices. PMID:27615125

  11. Unidirectional perfect absorber

    NASA Astrophysics Data System (ADS)

    Jin, L.; Wang, P.; Song, Z.

    2016-09-01

    This study proposes a unidirectional perfect absorber (UPA), which we realized with a two-arm Aharonov-Bohm interferometer, that consists of a dissipative resonator side-coupled to a uniform resonator array. The UPA has reflection-less full absorption on one direction, and reflectionless full transmission on the other, with an appropriate magnetic flux and coupling, detuning, and loss of the side-coupled resonator. The magnetic flux controls the transmission, the left transmission is larger for magnetic flux less than one-half flux quantum; and the right transmission is larger for magnetic flux between one-half and one flux quantum. Besides, a perfect absorber (PA) can be realized based on the UPA, in which light waves from both sides, with arbitrary superposition of the ampli- tude and phase, are perfectly absorbed. The UPA is expected to be useful in the design of novel optical devices.

  12. Time-domain reflectance diffuse optical tomography with Mellin-Laplace transform for experimental detection and depth localization of a single absorbing inclusion

    PubMed Central

    Puszka, Agathe; Hervé, Lionel; Planat-Chrétien, Anne; Koenig, Anne; Derouard, Jacques; Dinten, Jean-Marc

    2013-01-01

    We show how to apply the Mellin-Laplace transform to process time-resolved reflectance measurements for diffuse optical tomography. We illustrate this method on simulated signals incorporating the main sources of experimental noise and suggest how to fine-tune the method in order to detect the deepest absorbing inclusions and optimize their localization in depth, depending on the dynamic range of the measurement. To finish, we apply this method to measurements acquired with a setup including a femtosecond laser, photomultipliers and a time-correlated single photon counting board. Simulations and experiments are illustrated for a probe featuring the interfiber distance of 1.5 cm and show the potential of time-resolved techniques for imaging absorption contrast in depth with this geometry. PMID:23577292

  13. Effects of increased collagen-matrix density on the mechanical properties and in vivo absorbability of hydroxyapatite-collagen composites as artificial bone materials.

    PubMed

    Yunoki, Shunji; Sugiura, Hiroaki; Ikoma, Toshiyuki; Kondo, Eiji; Yasuda, Kazunori; Tanaka, Junzo

    2011-02-01

    The aim of this study was to evaluate the effects of increased collagen-matrix density on the mechanical properties and in vivo absorbability of porous hydroxyapatite (HAp)-collagen composites as artificial bone materials. Seven types of porous HAp-collagen composites were prepared from HAp nanocrystals and dense collagen fibrils. Their densities and HAp/collagen weight ratios ranged from 122 to 331 mg cm⁻³ and from 20/80 to 80/20, respectively. The flexural modulus and strength increased with an increase in density, reaching 2.46 ± 0.48 and 0.651 ± 0.103 MPa, respectively. The porous composites with a higher collagen-matrix density exhibited much higher mechanical properties at the same densities, suggesting that increasing the collagen-matrix density is an effective way of improving the mechanical properties. It was also suggested that other structural factors in addition to collagen-matrix density are required to achieve bone-like mechanical properties. The in vivo absorbability of the composites was investigated in bone defects of rabbit femurs, demonstrating that the absorption rate decreased with increases in the composite density. An exhaustive increase in density is probably limited by decreases in absorbability as artificial bones.

  14. A building block approach towards novel nonlinear optical materials

    NASA Astrophysics Data System (ADS)

    Bhaskar, Ajit

    The purpose of the present research is to develop and apply a building block approach towards the design of novel nonlinear optical (NLO) materials, capable of exhibiting enhanced Two-Photon Absorption (TPA) behavior. These materials have potential applications in biological imaging, microfabrication, sensing, photodynamic cancer therapy, optical limiting and ultrafast switching. Electronic structure, symmetry and intermolecular forces are vital for designing the right building block. The next step is to connect them to form macromolecules. However, besides covalent bonding, aggregation and self assembly of building blocks can also be utilized, which renders the strategies for materials design less reliant on chemical synthesis. The application of building block approach was illustrated using several examples, including rigid, two-dimensional architectures. These enabled the investigation of macrostructures that were synthetically inaccessible as well as demonstrated the influence of symmetry on TPA behavior. Electronic coupling between building blocks and excited state dynamics were the observed reasons for enhanced TPA. In an attempt to investigate strong coupling that would extend over the entire chromophore, novel "endless" nano-cavities were examined for their TPA behavior. Using the tools of ultrafast spectroscopy, complete delocalization was proved in these materials. Similar enhancement in giant porphyrin macrocycles, which mimic natural light harvesting systems, was observed. Another approach to harness the coupling between small building blocks in a synergistic fashion is to arrange them into branched architectures. The influence of pi-character of branching units on the charge transfer character, which in turn influences the TPA behavior, was examined. Using excited state studies, not only was it observed that alkene pi-bridging resulted in enhancement of TPA behavior over alkyne pi-bridging, but also the mechanism for cooperative enhancement upon

  15. Microstructure and Optical Properties of SS/Mo/Al2O3 Spectrally Selective Solar Absorber Coating

    NASA Astrophysics Data System (ADS)

    Gao, Xiang-Hu; Guo, Zhi-Ming; Geng, Qing-Fen; Ma, Peng-Jun; Liu, Gang

    2017-01-01

    Surface-textured Mo thin film is fabricated by magnetron sputtering through the adjustment of deposition parameters, which exhibits a high absorptance of 0.80 and a low emittance of 0.09. The single-layer Mo deposited on stainless steel (SS) is characterized by x-ray diffraction (XRD), ultra-high resolution scanning electron microscope, atomic force microscope and optical measurement. The controlled surface roughness combined with larger aspect ratio contributes much to the high absorptance and low emittance. Based on the SS/Mo coating, a spectrally selective coating (SS/Mo/Al2O3) is designed and fabricated. The coating shows an amorphous structure and exhibits an absorptance of 0.90 and an emittance of 0.08. Tauc-Lorentz and Drude free-electron models are used to modeling the optical properties of Al2O3 and Mo layers by phase-modulated spectroscopic ellipsometry.

  16. Microstructure and Optical Properties of SS/Mo/Al2O3 Spectrally Selective Solar Absorber Coating

    NASA Astrophysics Data System (ADS)

    Gao, Xiang-Hu; Guo, Zhi-Ming; Geng, Qing-Fen; Ma, Peng-Jun; Liu, Gang

    2016-11-01

    Surface-textured Mo thin film is fabricated by magnetron sputtering through the adjustment of deposition parameters, which exhibits a high absorptance of 0.80 and a low emittance of 0.09. The single-layer Mo deposited on stainless steel (SS) is characterized by x-ray diffraction (XRD), ultra-high resolution scanning electron microscope, atomic force microscope and optical measurement. The controlled surface roughness combined with larger aspect ratio contributes much to the high absorptance and low emittance. Based on the SS/Mo coating, a spectrally selective coating (SS/Mo/Al2O3) is designed and fabricated. The coating shows an amorphous structure and exhibits an absorptance of 0.90 and an emittance of 0.08. Tauc-Lorentz and Drude free-electron models are used to modeling the optical properties of Al2O3 and Mo layers by phase-modulated spectroscopic ellipsometry.

  17. Laser induced damage in optical materials: eleventh ASTM symposium.

    PubMed

    Bennett, H E; Glass, A J; Guenther, A H; Newnam, B

    1980-07-15

    The eleventh Symposium on Optical Materials for High-Power Lasers (Boulder Damage Symposium) was held at the National Bureau of Standards in Boulder, Colorado, 30-31 October 1979. The symposium was held under the auspices of ASTM Committee F-1, Subcommittee on Laser Standards, with the joint sponsorship of NBS, the Defense Advanced Research Projects Agency, the Department of Energy, and the Office of Naval Research. About 150 scientists attended the symposium, including representatives of the United Kingdom, France, Canada, Japan, West Germany, and Denmark. The symposium was divided into sessions concerning transparent optical materials and the measurement of their properties, mirrors and surfaces, thin film characteristics, thin film damage, considerations for high-power systems, and finally theory and breakdown. As in previous years, the emphasis of the papers presented at the symposium was directed toward new frontiers and new developments. Particular emphasis was given to materials for high-power apparatus. The wavelength range of prime interest was from 10.6 microm to the UV region. Highlights included surface characterization, thin film-substrate boundaries, and advances in fundamental laser-matter threshold interactions and mechanisms. The scaling of damage thresholds with pulse duration, focal area, and wavelength was discussed in detail. Harold E. Bennett of the Naval Weapons Center, Alexander J. Glass of the Lawrence Livermore Laboratory, Arthur H. Guenther of the Air Force Weapons Laboratory, and Brian E. Newnam of the Los Alamos Scientific Laboratory were cochairpersons. The twelfth annual symposium is scheduled for 30 September-1 October 1980 at the National Bureau of Standards, Boulder, Colorado.

  18. Surface Material Characterization from Multi-band Optical Observations

    NASA Astrophysics Data System (ADS)

    Hall, D.

    2010-09-01

    Ground-based optical and radar sites routinely acquire resolved images of satellites. These resolved images provide the means to construct accurate wire-frame models of the observed body, as well as an understanding of its orientation as a function of time. Unfortunately, because such images are typically acquired in a single spectral band, they provide little information on the types of materials covering the satellite's various surfaces. Detailed surface material characterization generally requires spectrometric and/or multi-band photometric measurements. Fortunately, many instruments provide such multi-band information (e.g., spectrographs and multi-channel photometers). However, these sensors often measure the brightness of the entire satellite, with no spatial resolution at all. Because such whole-body measurements represent a summation of contributions from many reflecting surfaces, an ―un-mixing‖ or inversion process must be employed to determine the materials covering each of the satellite's individual sub-components. The first section of this paper describes the inversion theory required to retrieve satellite surface material properties from temporal sequences of whole-body multi-band brightness measurements. The inversion requires the following as input: 1) a set of multi-band measurements of a satellite's reflected-sunlight brightness, 2) the satellite's wire-frame model, including each major component capable of reflecting sunlight, 3) the satellite's attitude, specifying the body’s orientation at the time of each multi-band measurement, and 4) a database of bi-directional reflection distribution functions for a set of candidate surface materials. As output, the inversion process yields estimates of the fraction of each major satellite component covered by each candidate material. The second section of the paper describes several tests of the method by applying it to simulated multi-band observations of a cubical satellite with different materials

  19. Effect of sound-absorbing materials on intensity of disturbances in the shock layer on a flat plate aligned at an angle of attack

    NASA Astrophysics Data System (ADS)

    Maslov, A. A.; Mironov, S. G.; Poplavskaya, T. V.; Tsyryulnikov, I. S.; Kirilovskiy, S. V.

    2012-03-01

    Results of a numerical and experimental study of characteristics of disturbances in a hypersonic shock layer on a flat plate covered by a sound-absorbing coating and aligned at an angle of attack are presented. Experiments and computations are performed for the free-stream Mach number M ∞ = 21 and Reynolds number Re L = 6 · 104. A possibility of suppressing pressure fluctuations in the shock layer at frequencies of 20-40 kHz with the use of tubular and porous materials incorporated into the plate surface is demonstrated. Results of numerical simulations are found to be in good agreement with experimental data.

  20. Crystalline perfection, optical and dielectric studies on L-histidine nitrate: A nonlinear optical material

    NASA Astrophysics Data System (ADS)

    Riscob, B.; Kushwaha, S. K.; Shakir, Mohd.; Nagarajan, K.; Maurya, K. K.; Haranath, D.; Roy, S. D. D.; Bhagavannarayana, G.

    2011-12-01

    Single crystals of L-histidine nitrate (LHN), a recently investigated nonlinear optical material, were grown by conventional solution technique. Crystal structure and vibrational modes of the grown crystals were confirmed by powder X-ray diffractometry and FT-Raman spectrometry, respectively. Crystalline perfection of the grown crystals was evaluated by employing an in-house developed high-resolution X-ray diffractometer (HRXRD) and it was found that the grown crystals were free from structural grain boundaries and the perfection was reasonably good. However, HRXRD could reveal the fact that the crystals contain predominantly the interstitial point defects. The birefringence was measured over a range of wavelength between 5480 and 5630 Å and it was found that its value is nearly constant and 10 times higher than that of KDP. The optical band gap was found to be ∼3.73 eV. The photoluminescence excitation and emission spectra for single crystals were recorded. The SHG efficiencies of LHN samples of different particle sizes were measured by the Kurtz and Perry technique and they removed the ambiguity in the values reported differently in the literature. Dielectric properties were studied as a function of temperature over a wide range of frequency. The optical and dielectric studies along with the crystalline perfection reveal that the LHN crystal could be a good candidate for nonlinear optical devices.

  1. Colour and Optical Properties of Materials: An Exploration of the Relationship Between Light, the Optical Properties of Materials and Colour

    NASA Astrophysics Data System (ADS)

    Tilley, Richard J. D.

    2003-05-01

    Colour is an important and integral part of everyday life, and an understanding and knowledge of the scientific principles behind colour, with its many applications and uses, is becoming increasingly important to a wide range of academic disciplines, from physical, medical and biological sciences through to the arts. Colour and the Optical Properties of Materials carefully introduces the science behind the subject, along with many modern and cutting-edge applications, chose to appeal to today's students. For science students, it provides a broad introduction to the subject and the many applications of colour. To more applied students, such as engineering and arts students, it provides the essential scientific background to colour and the many applications. Features: * Introduces the science behind the subject whilst closely connecting it to modern applications, such as colour displays, optical amplifiers and colour centre lasers * Richly illustrated with full-colour plates * Includes many worked examples, along with problems and exercises at the end of each chapter and selected answers at the back of the book * A Web site, including additional problems and full solutions to all the problems, which may be accessed at: www.cardiff.ac.uk/uwcc/engin/staff/rdjt/colour Written for students taking an introductory course in colour in a wide range of disciplines such as physics, chemistry, engineering, materials science, computer science, design, photography, architecture and textiles.

  2. Estimate of the Impact of Absorbing Aerosol Over Cloud on the MODIS Retrievals of Cloud Optical Thickness and Effective Radius Using Two Independent Retrievals of Liquid Water Path

    NASA Technical Reports Server (NTRS)

    Wilcox, Eric M.; Harshvardhan; Platnick, Steven

    2009-01-01

    Two independent satellite retrievals of cloud liquid water path (LWP) from the NASA Aqua satellite are used to diagnose the impact of absorbing biomass burning aerosol overlaying boundary-layer marine water clouds on the Moderate Resolution Imaging Spectrometer (MODIS) retrievals of cloud optical thickness (tau) and cloud droplet effective radius (r(sub e)). In the MODIS retrieval over oceans, cloud reflectance in the 0.86-micrometer and 2.13-micrometer bands is used to simultaneously retrieve tau and r(sub e). A low bias in the MODIS tau retrieval may result from reductions in the 0.86-micrometer reflectance, which is only very weakly absorbed by clouds, owing to absorption by aerosols in cases where biomass burning aerosols occur above water clouds. MODIS LWP, derived from the product of the retrieved tau and r(sub e), is compared with LWP ocean retrievals from the Advanced Microwave Scanning Radiometer-EOS (AMSR-E), determined from cloud microwave emission that is transparent to aerosols. For the coastal Atlantic southern African region investigated in this study, a systematic difference between AMSR-E and MODIS LWP retrievals is found for stratocumulus clouds over three biomass burning months in 2005 and 2006 that is consistent with above-cloud absorbing aerosols. Biomass burning aerosol is detected using the ultraviolet aerosol index from the Ozone Monitoring Instrument (OMI) on the Aura satellite. The LWP difference (AMSR-E minus MODIS) increases both with increasing tau and increasing OMI aerosol index. During the biomass burning season the mean LWP difference is 14 g per square meters, which is within the 15-20 g per square meter range of estimated uncertainties in instantaneous LWP retrievals. For samples with only low amounts of overlaying smoke (OMI AI less than or equal to 1) the difference is 9.4, suggesting that the impact of smoke aerosols on the mean MODIS LWP is 5.6 g per square meter. Only for scenes with OMI aerosol index greater than 2 does the

  3. Autogenic synthesis of SnO{sub 2} materials and their structural, electrochemical, and optical properties

    SciTech Connect

    Pol, V.G.; Calderon-Moreno, J.M.; Thackeray, M.M.

    2012-12-15

    During autogenic reactions, organometallic precursors are decomposed above their critical temperature within an enclosed chamber at high temperatures and pressures. It has recently been established that such reactions can be used to synthesize carbon-coated metal oxide and metal phosphate nanoparticles. These materials are of interest as electrodes for lithium-ion batteries. In this paper, we report the autogenic fabrication of a carbon-coated SnO{sub 2} product and a carbon-free SnO{sub 2} product after removal of the carbon coating by combustion. The major objectives of the study were to monitor any beneficial effects that carbon-coated electrodes containing a lithium alloying element such as Sn might have in improving the electrical connectivity between electrode particles, which expand and contract significantly on lithiation and delithiation, and their utility in lithium cells. Specifically, we report the compositional, structural and morphological properties, and electrochemical behavior of carbon-coated SnO{sub 2} electrodes. Given the importance of the optical properties of SnO{sub 2}, we also describe the effects of the carbon coating on the optical absorbance and photoluminescence of autogenically-prepared SnO{sub 2} materials. - Graphical abstract: One-step, solvent-free autogenic reactions yield nanosized SnO{sub 2} nanoparticles, uniformly coated and interconnected by 2-4 nm carbon layers, with improved electrochemical performance. Highlights: Black-Right-Pointing-Pointer Distinctive autogenic process synthesized SnO{sub 2} nanoparticles coated with 2-4 nm carbon layers. Black-Right-Pointing-Pointer Carbon coating improved capacity retention and cycling stability of SnO{sub 2} nanoparticles. Black-Right-Pointing-Pointer Carbon coating quenched photoluminescence of SnO{sub 2} component in SnO{sub 2}-C composite. Black-Right-Pointing-Pointer Autogenic approach is extremely versatile, holds promise for designing new nanoarchitectures.

  4. Laser-induced damage in optical materials: sixteenth ASTM symposium.

    PubMed

    Bennett, H E; Guenther, A H; Milam, D; Newnam, B E

    1987-03-01

    The Sixteenth Annual Symposium on Optical Materials for High Power Lasers (Boulder Damage Symposium) was held at the National Bureau of Standards in Boulder, CO, 15-17 Oct. 1984. The Symposium was held under the auspices of ASTM Committee F-1, Subcommittee on Laser Standards, with the joint sponsorship of NBS, the Defense Advanced Research Project Agency, the Department of Energy, the Office of Naval Research, and the Air Force Office of Scientific Research. Approximately 180 scientists attended the Symposium, including representatives from England, France, The Netherlands, Scotland, and West Germany. The Symposium was divided into sessions concerning Materials and Measurements, Mirrors and Surfaces, Thin Films, and Fundamental Mechanisms. As in previous years, the emphasis of the papers presented at the Symposium was directed toward new frontiers and new developments. Particular emphasis was given to materials for high-power apparatus. The wavelength range of prime interest was from 10.6,microm to the UV region. Highlights included surface characterization, thin-film-substrate boundaries, and advances in fundamental laser-matter threshold interactions and mechanisms. Harold E. Bennett of the U.S. Naval Weapons Center, Arthur H. Guenther of the U.S. Air Force Weapons Laboratory, David Milam of the Lawrence Livermore National Laboratory, and Brian E. Newnam of the Los Alamos National Laboratory were cochairmen of the Symposium.

  5. Laser induced damage in optical materials: ninth ASTM symposium.

    PubMed

    Glass, A J; Guenther, A H

    1978-08-01

    The Ninth Annual Symposium on Optical Materials for High Power Lasers (Boulder Damage Symposium) was held at the National Bureau of Standards in Boulder, Colorado, 4-6 October 1977. The symposium was under the auspices of ASTM Committee F-1, Subcommittee on Laser Standards, with the joint sponsorship of NBS, the Defense Advanced Research Project Agency, the Department of Energy (formerly ERDA), and the Office of Naval Research. About 185 scientists attended, including representatives of the United Kingdom, France, Canada, Australia, Union of South Africa, and the Soviet Union. The Symposium was divided into sessions concerning Laser Windows and Materials, Mirrors and Surfaces, Thin Films, Laser Glass and Glass Lasers, and Fundamental Mechanisms. As in previous years, the emphasis of the papers was directed toward new frontiers and new developments. Particular emphasis was given to materials for use from 10.6 microm to the uv region. Highlights included surface characterization, thin film-substrate boundaries, and advances in fundamental laser-matter threshold interactions and mechanisms. The scaling of damage thresholds with pulse duration, focal area, and wavelength were also discussed. Alexander J. Glass of Lawrence Livermore Laboratory and Arthur H. Guenther of the Air Force Weapons Laboratory were co-chairpersons. The Tenth Annual Symposium is scheduled for 12-14 September 1978 at the National Bureau of Standards, Boulder, Colorado.

  6. Optical characteristics and visual appearance for artwork materials

    NASA Astrophysics Data System (ADS)

    Radis, M.; Iacomussi, P.; Aghemo, C.

    2015-06-01

    The aim of this study is to evaluate experimentally how well available metrics are able to evaluate how lighting sources affect the perception of visual attributes of artworks exhibited, providing useful indications for works of art exhibition designers. The study considers objective investigations on optical material properties (i.e. spectral reflection factor) compared to subjective tests on colour attributes evaluation of artworks lighted by common lamps (incandescent and fluorescent lamps) and LED lighting sources. Commission International Eclairage (CIE) developed several mathematical methods to predict colour rendering of lighting source, as well visual attributes of materials, but are only an approximation of the material appearance: too many parameters of influence, subjects expectancy included, influence the appearance. In artwork exhibition visual appearance is of fundamental importance and currently no reliable and robust appearance model is available. Comparing objective evaluations and subjective results for lighting set up comparable to works of art exhibition, will provide useful indications on the applicability of colorimetric calculation to artwork exhibition when LED are involved. Visual attributes (hue, saturation, brightness…) of six different colours under LED and not-LED sources at the same Correlate Colour Temperature were compared to the associate objective characteristics calculated from the spectral reflectance. The results show that the perception of visual attributes differs from objective data when SSL sources are involved and when colours are perceived in complex samples: in some cases the visual system is not coherent with the suggestions arising from the calculations.

  7. Removal of Nitrate by Photocatalytic Denitrification Using Nonlinear Optical Material.

    PubMed

    Liu, Guoshuai; You, Shijie; Ma, Ming; Huang, Hong; Ren, Nanqi

    2016-10-18

    Removal of nitrate from water has been receiving growing attention in water treatment. In this study, we report the photocatalytic denitrification (PCDN) by nonlinear optical (NLO) material, i.e. lithium niobate (LiNbO3). The hydrothermally synthesized LiNbO3 powder could achieve efficient denitrification in water, evidenced by 98.4% nitrate removal and 95.8% nitrogen selectivity at reaction time of 120 min and pH-neutral condition. Based on the first-order kinetics of PCDN, the kinetic constant for LiNbO3 is almost three times as that of conventional TiO2 (P25) under the same conditions. As suggested by the hole scavenger experiments, the LiNbO3 should proceed with photocatalytic reduction of nitrate through direct heterogeneous interaction with electrons at the conduction band of LiNbO3. This may represent a different mechanism from P25, where nitrate is mainly reduced by CO2(•-) radicals generated by the holes at the valence band. The unique second harmonic generation (SHG) effects of NLO materials enable them to produce more electrons and minimize the electron-hole recombination, which improves the efficiency and stability of the PCDN process. The current study provides a proof-of-concept demonstration of NLO photocatalytic material for more effective nitrate removal in water treatment.

  8. LOW-RESOLUTION SPECTROSCOPY OF GAMMA-RAY BURST OPTICAL AFTERGLOWS: BIASES IN THE SWIFT SAMPLE AND CHARACTERIZATION OF THE ABSORBERS

    SciTech Connect

    Fynbo, J. P. U.; Malesani, D.; Vreeswijk, P. M.; Hjorth, J.; Sollerman, J.; Thoene, C. C.; Jakobsson, P.; Bjoernsson, G.; De Cia, A.; Prochaska, J. X.; Nardini, M.; Chen, H.-W.; Bloom, J. S.; Castro-Tirado, A. J.; Gorosabel, J.; Christensen, L.; Fruchter, A. S.

    2009-12-01

    We present a sample of 77 optical afterglows (OAs) of Swift detected gamma-ray bursts (GRBs) for which spectroscopic follow-up observations have been secured. Our first objective is to measure the redshifts of the bursts. For the majority (90%) of the afterglows, the redshifts have been determined from the spectra. We provide line lists and equivalent widths (EWs) for all detected lines redward of Ly{alpha} covered by the spectra. In addition to the GRB absorption systems, these lists include line strengths for a total of 33 intervening absorption systems. We discuss to what extent the current sample of Swift bursts with OA spectroscopy is a biased subsample of all Swift detected GRBs. For that purpose we define an X-ray-selected statistical sample of Swift bursts with optimal conditions for ground-based follow-up from the period 2005 March to 2008 September; 146 bursts fulfill our sample criteria. We derive the redshift distribution for the statistical (X-ray selected) sample and conclude that less than 18% of Swift bursts can be at z > 7. We compare the high-energy properties (e.g., {gamma}-ray (15-350 keV) fluence and duration, X-ray flux, and excess absorption) for three subsamples of bursts in the statistical sample: (1) bursts with redshifts measured from OA spectroscopy; (2) bursts with detected optical and/or near-IR afterglow, but no afterglow-based redshift; and (3) bursts with no detection of the OA. The bursts in group (1) have slightly higher {gamma}-ray fluences and higher X-ray fluxes and significantly less excess X-ray absorption than bursts in the other two groups. In addition, the fractions of dark bursts, defined as bursts with an optical to X-ray slope {beta}{sub OX} < 0.5, is 14% in group (1), 38% in group (2), and >39% in group (3). For the full sample, the dark burst fraction is constrained to be in the range 25%-42%. From this we conclude that the sample of GRBs with OA spectroscopy is not representative for all Swift bursts, most likely due

  9. Optical processing deep inside optical materials using counterpropagating pulse-shaped spatial solitons

    NASA Astrophysics Data System (ADS)

    Hisaka, Masaki

    2016-10-01

    Optical processing using a pair of counterpropagating pulse-shaped spatial solitons to control the molecular structure deep inside an optical material is investigated. A femtosecond pulsed laser focused at the surface of a strontium barium niobate single crystal induces a pulse-shaped self-focusing second-harmonic beam. The two counterpropagating beams are involved in a head-on collision. Locally reversed crystal domains are formed at the collision point, assisted by external threshold controls such as crystal temperature and an electric dc field. The nonlinear interaction between the soliton collision and the approximate nonperiodic reversed domains induces a change in the second-harmonic intensity of the scattered and transmitted beams, thereby enabling the detection of locally reversed crystal domains.

  10. Broadband patterned magnetic microwave absorber

    SciTech Connect

    Li, Wei; Wu, Tianlong; Wang, Wei; Guan, Jianguo; Zhai, Pengcheng

    2014-07-28

    It is a tough task to greatly improve the working bandwidth for the traditional flat microwave absorbers because of the restriction of available material parameters. In this work, a simple patterning method is proposed to drastically broaden the absorption bandwidth of a conventional magnetic absorber. As a demonstration, an ultra-broadband microwave absorber with more than 90% absorption in the frequency range of 4–40 GHz is designed and experimentally realized, which has a thin thickness of 3.7 mm and a light weight equivalent to a 2-mm-thick flat absorber. In such a patterned absorber, the broadband strong absorption is mainly originated from the simultaneous incorporation of multiple λ/4 resonances and edge diffraction effects. This work provides a facile route to greatly extend the microwave absorption bandwidth for the currently available absorbing materials.

  11. Fiber Optic Thermal Health Monitoring of Aerospace Structures and Materials

    NASA Technical Reports Server (NTRS)

    Wu, Meng-Chou; Winfree, William P.; Allison, Sidney G.

    2009-01-01

    A new technique is presented for thermographic detection of flaws in materials and structures by performing temperature measurements with fiber Bragg gratings. Individual optical fibers with multiple Bragg gratings employed as surface temperature sensors were bonded to the surfaces of structures with subsurface defects or thickness variations. Both during and following the application of a thermal heat flux to the surface, the individual Bragg grating sensors measured the temporal and spatial temperature variations. The investigated structures included a 10-ply composite specimen with subsurface delaminations of various sizes and depths. The data obtained from grating sensors were further analyzed with thermal modeling to reveal particular characteristics of the interested areas. These results were found to be consistent with those from conventional thermography techniques. Limitations of the technique were investigated using both experimental and numerical simulation techniques. Methods for performing in-situ structural health monitoring are discussed.

  12. Degradation study on optical materials for concentrator photovoltaics

    NASA Astrophysics Data System (ADS)

    Eltermann, Fabian; Roeder, Kerstin; Wiesenfarth, Maike; Wilde, Juergen; Bett, Andreas W.

    2012-10-01

    In this work the impact of accelerated aging on the spectral transmission and the mechanical robustness of silicone elastomers for concentrator photovoltaic applications was investigated. Therefore, specific test samples were manufactured. The samples were annealed at 150 °C to assure a complete cross-linking. These samples were exposed to humidity freeze, to a pressure cooker test, and to UV light. To investigate optical materials under UVA intensity up to 10 W/cm2 a test setup was developed. Thus, a UV dosage of 10000 kWh/m2 was applied to the silicone samples after thermal treatment. The mean transmission was used as a measure to identify changes in the spectral behavior and was, therefore, compared after the stress tests with the initial value. No total failures but rather degradation was observed, mainly in the range of ultraviolet and visible light. In addition, the shear strengths for the silicone elastomers were compared before and after stress.

  13. Neutron Absorbing Alloys

    SciTech Connect

    Mizia, Ronald E.; Shaber, Eric L.; DuPont, John N.; Robino, Charles V.; Williams, David B.

    2004-05-04

    The present invention is drawn to new classes of advanced neutron absorbing structural materials for use in spent nuclear fuel applications requiring structural strength, weldability, and long term corrosion resistance. Particularly, an austenitic stainless steel alloy containing gadolinium and less than 5% of a ferrite content is disclosed. Additionally, a nickel-based alloy containing gadolinium and greater than 50% nickel is also disclosed.

  14. Theoretical and experimental study of the diffuse transmission of light through highly concentrated absorbing and scattering materials. Part I: Monte-Carlo simulations

    NASA Astrophysics Data System (ADS)

    Bressel, L.; Reich, O.

    2014-10-01

    In many technical materials and commercial products like sunscreen or paint high particle and absorber concentrations are present. An important parameter for slabs of these materials is the diffuse transmission of light, which quantifies the total amount of directly and diffusely transmitted light. Due to the high content of scattering particles not only multiple scattering but also additional dependent scattering occurs. Hence, simple analytical models cannot be applied to calculate the diffuse transmission. In this work a Monte-Carlo program for the calculation of the diffuse transmission of light through dispersions in slab-like geometry containing high concentrations of scattering particles and absorbers is presented and discussed in detail. Mie theory is applied for the calculation of the scattering properties of the samples. Additionally, dependent scattering is considered in two different models, the well-known hard sphere model in the Percus-Yevick approximation (HSPYA) and the Yukawa model in the Mean Spherical Approximation (YMSA). Comparative experiments will show the accurateness of the program as well as its applicability to real samples [1].

  15. Application of ICP-OES to the determination of CuIn(1-x)Ga(x)Se2 thin films used as absorber materials in solar cell devices.

    PubMed

    Fernández-Martínez, Rodolfo; Caballero, Raquel; Guillén, Cecilia; Gutiérrez, María Teresa; Rucandio, María Isabel

    2005-05-01

    CuIn(1-x)Ga(x)Se2 [CIGS; x=Ga/(In+Ga)] thin films are among of the best candidates as absorber materials for solar cell applications. The material quality and main properties of the polycrystalline absorber layer are critically influenced by deviations in the stoichiometry, particularly in the Cu/(In+Ga) atomic ratio. In this work a simple, sensitive and accurate method has been developed for the quantitative determination of these thin films by inductively coupled plasma optical emission spectrometry (ICP-OES). The proposed method involves an acid digestion of the samples to achieve the complete solubilization of CIGS, followed by the analytical determination by ICP-OES. A digestion procedure with 50% HNO3 alone or in the presence of 10% HCl was performed to dissolve those thin films deposited on glass or Mo-coated glass substrates, respectively. Two analytical lines were selected for each element (Cu 324.754 and 327.396 nm, Ga 294.364 and 417.206 nm, In 303.936 and 325.609 nm, Se 196.090 and 203.985 nm, and Mo 202.030 and 379.825 nm) and a study of spectral interferences was performed which showed them to be suitable, since they offered a high sensitivity and no significant inter-element interferences were detected. Detection limits for all elements at the selected lines were found to be appropriate for this kind of application, and the relative standard deviations were lower than 1.5% for all elements with the exception of Se (about 5%). The Cu/(In+Ga) atomic ratios obtained from the application of this method to CIGS thin films were consistent with the study of the structural and morphological properties by X-ray diffraction (XRD) and scanning electron microscopy (SEM).

  16. Sodium antimony sulfide (NaSbS2): Turning an unexpected impurity into a promising, environmentally friendly novel solar absorber material

    NASA Astrophysics Data System (ADS)

    Rahayu, Siti Utari; Chou, Chia-Ling; Suriyawong, Nipapon; Aragaw, Belete Asefa; Shi, Jen-Bin; Lee, Ming-Way

    2016-11-01

    We present a novel absorber material—NaSbS2—for solar cells. NaSbS2 is formed as an unexpected byproduct in the chemical synthesis of Sb2S3. However, NaSbS2 has many attractive features for a solar material. Here single phase NaSbS2 nanoparticles were synthesized through solution processing. NaSbS2 semiconductor-sensitized solar cells were demonstrated for the first time. The best cell yielded Jsc = 10.76 mA/cm2, Voc = 0.44 V, FF = 48.6%, and efficiency η = 2.30% under 1 sun. At the reduced 0.1 sun, the η increased to 3.18%—a respectable η for a new solar material.

  17. All-Silicon Ultra-Broadband Infrared Light Absorbers

    PubMed Central

    Gorgulu, Kazim; Gok, Abdullah; Yilmaz, Mehmet; Topalli, Kagan; Bıyıklı, Necmi; Okyay, Ali K.

    2016-01-01

    Absorbing infrared radiation efficiently is important for critical applications such as thermal imaging and infrared spectroscopy. Common infrared absorbing materials are not standard in Si VLSI technology. We demonstrate ultra-broadband mid-infrared absorbers based purely on silicon. Broadband absorption is achieved by the combined effects of free carrier absorption, and vibrational and plasmonic absorption resonances. The absorbers, consisting of periodically arranged silicon gratings, can be fabricated using standard optical lithography and deep reactive ion etching techniques, allowing for cost-effective and wafer-scale fabrication of micro-structures. Absorption wavebands in excess of 15 micrometers (5–20 μm) are demonstrated with more than 90% average absorptivity. The structures also exhibit broadband absorption performance even at large angles of incidence (θ = 50°), and independent of polarization. PMID:27924933

  18. Apollo couch energy absorbers

    NASA Technical Reports Server (NTRS)

    Wesselski, C. J.; Drexel, R. E.

    1972-01-01

    Load attenuators for the Apollo spacecraft crew couch and its potential applications are described. Energy absorption is achieved through friction and cyclic deformation of material. In one concept, energy absorption is accomplished by rolling a compressed ring of metal between two surfaces. In another concept, energy is absorbed by forcing a plastically deformed washer along a rod. Among the design problems that had to be solved were material selection, fatigue life, ring slippage, lubrication, and friction loading.

  19. Flouescence reference materials used for optical and biophotonic applications

    NASA Astrophysics Data System (ADS)

    Engel, A.; Otterman, C.; Klahn, J.; Enseling, D.; Korb, T.; Resch-Genger, U.; Hoffmann, K.; Schweizer, S.; Selling, J.; Kynast, U.; Koberling, F.; Rupertus, V.

    2007-07-01

    Fluorescence techniques are known for their high sensitivity and are widely used as analytical tools and detection methods for product and process control, material sciences, environmental and bio-technical analysis, molecular genetics, cell biology, medical diagnostics, and drug screening. According to DIN/ISO 17025 certified standards are used for fluorescence diagnostics having the drawback of giving relative values for fluorescence intensities only. Therefore reference materials for a quantitative characterization have to be related directly to the materials under investigation. In order to evaluate these figures it is necessary to calculate absolute numbers like absorption/excitation cross sections and quantum yield. This can be done for different types of dopands in different materials like glass, glass ceramics, crystals or nano crystalline material embedded in polymer matrices. Based on the optical spectroscopy data we will discuss options for characteristic doped glasses and glass ceramics with respect to scattering and absorption regime. It has shown recently for YAG:Ce glass ceramics that for a proper determination of the quantum efficiency in these highly scattering media a reference material with similar scattering and fluorescent properties is required. This may be performed using the emission decay measurement diagnostics, where the decay time is below 100 ns. In this paper we present first results of these aspects using well performing LUMOGEN RED organic pigments for a comparison of mainly transparent glass with glass ceramics doped with various amounts of dopands e.g. ions of raw earth elements and transition metals. The LUMOGEN red is embedded in silica and polyurethane matrices. Characterisations on wavelength accuracy and lifetime for different environmental conditions (temperature, UV irradiation) have been performed. Moreover intensity patterns and results for homogeneity, isotropy, photo and thermal stability will be discussed. In a next

  20. Nonlinear Optical Properties of Organic and Polymeric Thin Film Materials of Potential for Microgravity Processing Studies

    NASA Technical Reports Server (NTRS)

    Abdeldayem, Hossin; Frazier, Donald O.; Paley, Mark S.; Penn, Benjamin; Witherow, William K.; Bank, Curtis; Shields, Angela; Hicks, Rosline; Ashley, Paul R.

    1996-01-01

    In this paper, we will take a closer look at the state of the art of polydiacetylene, and metal-free phthalocyanine films, in view of the microgravity impact on their optical properties, their nonlinear optical properties and their potential advantages for integrated optics. These materials have many attractive features with regard to their use in integrated optical circuits and optical switching. Thin films of these materials processed in microgravity environment show enhanced optical quality and better molecular alignment than those processed in unit gravity. Our studies of these materials indicate that microgravity can play a major role in integrated optics technology. Polydiacetylene films are produced by UV irradiation of monomer solution through an optical window. This novel technique of forming polydiacetylene thin films has been modified for constructing sophisticated micro-structure integrated optical patterns using a pre-programmed UV-Laser beam. Wave guiding through these thin films by the prism coupler technique has been demonstrated. The third order nonlinear parameters of these films have been evaluated. Metal-free phthalocyanine films of good optical quality are processed in our laboratories by vapor deposition technique. Initial studies on these films indicate that they have excellent chemical, laser, and environmental stability. They have large nonlinear optical parameters and show intrinsic optical bistability. This bistability is essential for optical logic gates and optical switching applications. Waveguiding and device making investigations of these materials are underway.